Научные проекты


За время обучения в Институте биоинформатики каждый студент занимается несколькими научно-исследовательскими проектами. Руководят проектами ведущие специалисты из российских и зарубежных научных лабораторий и компаний, работающих в области биоинформатики и биотехнологий.

Если у вас есть интересные задачи по биоинформатике для студентов пишите нам на info@bioinf.me.
Проект подразумевает еженедельные встречи с руководителем очно или по скайпу, а также 5-10 часов в неделю самостоятельной работы. Многие проекты выливаются в дальнейшее сотрудничество со студентами и потом выпускниками. Подробнее о формате проектов можно прочитать в этом гиде.

Институт биоинформатики публикует на сайте итоги и презентации всех студенческих проектов. С 2017 года результаты семестровых проектов переводятся на английский язык

Научные проекты разных лет:

Научные проекты 2019/2020
Осень 2019
Использование искусственных нейронных сетей для анализа вторичной структуры биологических последовательностей | СПбГУ / JetBrains Research (PLT Lab)

студенты: Кутленков Дмитрий, Конгоев Михаил
руководитель: Григорьев Семён
Известно, что формальные граммтики --- достаточно выразительный способ описания особенностей вторичной структуры. При этом, из-за особенностей реальных данных, приходится использовать вероятностные граммтики, что значительно усложняет и инструменты и процесс построения таких граммтик. Мы предлагаем использовать обычные контекстно-свободные граммтики, а в качестве вероятностной модели использовать нейронные сети.

В рамках осеннего семестра предлагается подготовить всё необходимое для того, чтобы создать нейронную сеть, способную предсказывать вторичную структуру цепочек. А если останется время, то и обучить такую сеть.
Импутация снипов с использованием данных генотипирования на чипах | Мираторг Генетика

студент: Файзуллина Камилла
руководители: Жегалова Ирина, Черняева Екатерина
Импутация – процесс "достраивания" отсутствующих снипов в генотипе с использованием референсной популяции. Импутация является одним из ключевых этапов протокола предобработки и контроля качества любого генетического исследования.
Использование более высокой плотности маркеров может привести к лучшим результатам, даже если индивидуумы не были генотипированы по большинству маркеров, кроме того, это позволяет заместить маркеры валидными значениями, в случаях, когда в точности генотипа мы не уверены.
Однако, большинство алгоритмов для импутации были первоначально разработаны для использования в генетике человека и поэтому оптимизированы для высокого уровня генетического разнообразия. Основной же особенностью сельскохозяйственной генетики является наличие большого количества близкородственных связей и потому умеренный уровень генетического разнообразия. Споры о пригодности тех или иных алгоритмов, равно как и о поиске "лучшего" алгоритма все еще ведутся. Потому основной целью проекта является реализация пайплайна для импутации снипов у коров для чипов разной плотности.
GWAS для определения особенностей метаболизма и поиск ассоциаций с заболеваниями | Мираторг Генетика

студенты: Карпова Наталия, Куреев Николай

руководители: Жегалова Ирина, Черняева Екатерина
GWAS, или полногеномный анализ ассоциаций, ответствен за поток открытий с точки зрения генетических факторов риска для заболевания или исследования причинно-следственной связи между генотипами и фенотипическими признаками. Исследования основаны на том, что есть большая когорота, в которой у каждого есть исследуемый признак\болезнь, и когорта, у которых этого признака\заболевания нет. И затем, просматривая весь геном с использованием SNP, вы пытаетесь найти мутацию, которая встречается у больных и нет у здоровых. Прелесть GWAS в том, что он помог нам преодолеть подход генов-кандидатов, который был довольно разочаровывающим, потому что большинство кандидатов не подтвердились расчетами, и вместо этого исходит из теории, что весь набор генов - кандидаты, давайте рассмотрим все из них. И вот стратегия, которая является достаточно всеобъемлющей, чтобы позволить вам сделать это.
Цель проекта – изучить связи фенотипов – хозяйственно важных признаков и заболеваний – и генотипов у коров породы Black Angus.
Dashboard for exploratory data analysis of large-scale immune repertoires | ImmunoMind

студент: Уразбахтин Шамиль

руководитель: Назаров Вадим
Адаптивная иммунная система - "невидимая рука" организма, направляющая триллионы лимфоцитов на защиту от различных патогенов. Ключевая особенность адаптивного иммунитета заключается в уникальной системе генерации его основных агентов - Б- и Т-клеточных рецепторов, которые находятся на поверхности соответствующих лимфоцитов. Вместо кодирования огромного объема информации о белках-рецепторах в геноме, организм генерирует случайные последовательности рецепторов в процессе соматической рекомбинации генов.

В процессе столкновения с различными заболеваниями, первоначально сгенерированное множество рецепторов - "репертуар" - изменяет свою структуру: некоторые рецепторы отфильтровываются, некоторые, наоборот, увеличивают свою численность в ответ на атаки вирусов или бактерий. Таким образом, иммунные репертуары сохраняют в себе историю борьбы с заболеваниями и текущее состояние иммунитета. Они содержат в себе много ценной информации, которую человечеству еще придется раскрыть - эта подобласть иммунологии появилась примерно десять лет назад.

Развитие технологий секвенирования позволило идентифицировать геномные последовательности для сотен тысяч вариантов клеточных рецепторов в образце крови или исследуемой ткани. Анализ таких данных позволяет, например, понять, что вызывает аутоиммунные заболевания, почему люди умирают от иммунотерапии, а также как изменяется иммунитет с возрастом.

Однако для эффективных исследований необходимы эффективные инструменты. На данный момент в мире существует всего два биоинфоматических пакета, которые позволяют удобно и быстро анализировать данные иммунных репертуаров - VDJtools и R пакет immunarch. В данной работе вам предлагается сделать immunarch еще более удобным для исследователей. Поскольку многие статьи дублируют методы анализа клеточных рецепторов, то это открывает возможность для оптимизации научного процесса и минимизации страданий исследователей. Разработав интерактивный дашборд, которые содержит в себе все самые встречаемые методы и визуализации для анализа иммунных репертуаров, можно сильно сократить время, которые исследователи тратят на программирование одних и тех же пайплайнов анализа, совершая каждый раз разные ошибки.

Цель проекта: ускорить процесс генерации научных инсайтов и минимизировать бессмысленные страдания исследователей за счет разработки интерактивного дашборда с наиболее часто встречаемыми подходами к анализу репертуаров иммунных рецепторов.
Оценка дифференцильной экспрессии изоформ генов интереса | ФГБУ «НИИ гриппа им. А.А. Смородинцева» Минздрава России

студенты: Цыба Дарья, Окорокова Лариса, Алексеев Дмитрий
руководители: Станевич Оксана, Бакин Евгений
В проекте предлагается оценить дифференциальную экспрессию изоформ генов - сначала на примере генов модельных организмов (дрожжи/C.elegans/дрозофила), затем, если останется время, на примере данных РНК-секвенирования из образцов рака молочной железы человека. Оценку дифференциальной экспрессии изоформ генов будет предложено произвести с использованием существующего пайплайна на инструменте Cufflinks. В случае успешного освоения пайплайна будет дана возможность сравнить свой результат с имеющимся - на данных из образцов рака молочной железы.
Разработка имитационной модели для формировании V-D и D-J регионов в последовательностях иммуноглобулинов | Институт Биоинформатики

студенты: Жукова Наталия, Репинская Жанна
руководители: Станевич Оксана, Бакин Евгений
V-D и D-J регионы CDR3-зоны иммуноглобулинов играют важную роль в обеспечении разнообразия репертуара антител и, как следствие, способности организма защищаться от различных патогенов. В рамках предыдущих студенческих проектов были созданы вероятностные модели для формирования регионов CDR3 зоны. Анализ показал, что, в силу некоторых введенных допущений, в ряде случаев модель обеспечивает недостаточно высокую точность. В данном проекте предлагается построить более точную, имитационную модель и с ее помощью проанализировать вклад различных механизмов в формирование указанных регионов.
Обработка данных РНК-секвенирования с целью изучения функций белка Pcbp1 | Институт Биоинформатики

студент: Потапенко Евгений
руководители: Станевич Оксана, Бакин Евгений
Pcbp1 является представителем семейства KH-доменных поли(Ц)-связывающих белков и участвует в регуляции множества процессов – транскрипции, трансляции и сплайсинге. В частности, существует гипотеза о важной роли Pcbp1 при переходе плюрипотентных стволовых клеток из раннего (наивного) в позднее (праймированное) состояние. В лаборатории молекулярной биологии стволовых клеток института цитологии РАН были получены 12 проб для анализа RNA-seq – по 3 биологических повторности дикого типа и нокаутных клеток в исходном и праймированном плюрипотентном состоянии. Целью данного проекта является оценка дифференциальной экспрессии генов в данных образцах для лучшего понимания вовлеченности Pcbp1 в различные сигнальные пути.
Апробация вероятностной модели формирования V-D и D-J зон CDR3 региона тяжелой цепи иммуноглобулинов на открытых данных | Институт Биоинформатики

студент: Петросян Степан
руководители: Станевич Оксана, Бакин Евгений
Студентам предлагается апробировать вероятностную модель формирования N1/N2 зон региона CDR3-VH иммуноглобулинов мышей и человека на ряде отобранных открытых данных.
Exploring properties of amino acids in immunoglobulin clonal lineages | UCSD

студент: Меженская Дарья
руководитель: Сафонова Яна
An antibody repertoire can be viewed as a collection of clonal lineages. Each clonal lineage presents a result of somatic hypermutagenesis and clonal selection and thus can be described as an evolutionary tree. The goal of this project is to analyze somatic hypermutations appearing in expanded clonal lineages and reveal associations between immunoglobulin positions and properties of amino acids generated through the mutation process.
Phenome-wide functional analysis of human genetic association data | Институт биоинформатики

студенты: Масликова Татьяна, Догонашева Олеся, Ушаков Михаил, Чангалиди Антон
руководители: Барбитов Юрий, Шиков Антон
Проект является продолжением работы нашей группы, опубликованной в виде препринта на bioRxiv (https://www.biorxiv.org/content/10.1101/672758v1). Мы интересуемся тем, какие гены и группы генов определяют различные группы признаков у человека. В данной работе мы хотим уйти от анализа отдельных генетических вариаций и их комбинаций к генам за счет аккуратной оценки степени ассоциации каждого гена с признаком. Получив такие оценки, мы хотим использовать различные статистические методы для функционального анализа фенома человека.
Охарактеризовать представителей Bacteroidetes и Firmicutes в кишечных микробиомах подростков | Научный центр проблем здоровья семьи и репродукции человека

студенты: Сарана Юлия, Селезнева Елизавета

руководитель: Белькова Наталья
Bacteroidetes и Firmicutes – это две филы бактерий, доминирующие в кишечных микробиомах человека. Их представленность и соотношение изменяется в течение жизни человека, зависит от генетических, средовых, социально-экономических и поведенческих факторов (возраст, тип питания, образ жизни и др.) и может опосредованно влиять на состояние здоровья.
Цель настоящего исследования – изучить состав, структуру и разнообразие представителей двух доминирующих фил бактерий в кишечных микробиомах подростков с разным индексом массы тела.
Вывод демографической истории популяций современных людей с помощью метода, основанного на модели Морана | Университет ИТМО

студенты: Биба Дмитрий, Волкова Мария, Яковлева Екатерина

руководитель: Носкова Екатерина
Демографическая истории популяций - история развития этих популяций, включающая в себя такие события как разделения популяций, изменение их численности и миграции. Демографическая история "Out of Africa" - одна из самых популярных историй развития трех популяций: народа Йоруба из Нигерии, европейцев и народа Хань из Пекина. Параметры такие как время разделения популяций, их численность и темпы миграций могут быть получены разными методами. На данный момент существует несколько программных обеспечений позволяющих вывести параметры по таким данным как аллель-частотный спектр (распределение частот аллелей в популяциях): например dadi (Gutenkunst et al., 2009) и moments (Jouganous et al., 2018). Однако они основаны на математической модели Райта-Фишера, которая описывает частоту аллелей при переходе от одного поколения особей к другому, предполагая, что поколения не пересекаются. Недавно появилось новое программное обеспечение momi2 (Kamm et al.), в основе которого лежит модель Морана, которая позволяет поколениям пересекаться, что делает ее более близкой к реальности. Задачей проекта является вывод параметров демографической истории современных людей с помощью momi2 и сравнение полученных результатов с параметрами, полученными ранее с помощью dadi и moments.
Investigation of yeast multilayer molecular network | Институт биоинформатики

студент: Штыкалова Софья
руководители: Барбитов Юрий, Скитченко Ростислав
В последние годы было проведено много экспериментов по систематическому анализу генетических взаимодействий. Например, в одной из работ (https://science.sciencemag.org/content/353/6306/aaf1420) были проанализированы взаимодействия 23 миллионов пар генов. Также в этой работе были проведены сравнения структуры сетей генетических взаимодействий, коэкспрессии генов и белок-белковых взаимодействий. В нашем проекте мы попробуем интегрировать все три вида данных (GI, co-expression, PPI) и найти в такой многослойной сети интересные паттерны, связанные с функциональными характеристиками генов и их продуктов.
Differential mutability of human genome regions | Институт биоинформатики

студент: Мамаева Мария
руководители: Барбитов Юрий, Скитченко Ростислав
Большая часть моделей в популяционной геномике принимает частоту мутирования за константу, которая не зависит от конкретного региона. Однако же, существует достаточно давно обсуждаемая концепция, согласно которой открытый и закрытый хроматин имеют различную подверженность мутагенезу. У этой гипотезы есть подтверждения на модельных организмах и на человеке (https://www.nature.com/articles/nature11273?proof=trueIn&draft=journal). Тем не менее, большая часть результатов была получена с использованием раковых данных и межвидового сравнения. В этом проекте мы хотим оценить локальную частоту мутирования с использованием популяционных данных и определить параметры, влияющие на эту частоту.
Inference of coevolutionary events from coalescent trees | Институт биоинформатики

студент: Дерябина Полина
руководители: Барбитов Юрий, Скитченко Ростислав
Коалесцентная теория предоставляет широкий арсенал для популяционногенетического анализа геномных данных. Так, с использованием коалесцентных методов с применением скрытых марковских цепей были сделаны оценки размера динамики размера популяций и даже давления отбора (https://www.nature.com/articles/s41588-018-0177-x). В этом проекте мы хотим использовать метод ASMC (см. статью) для построения локус-специфических коалесцентных деревьев. Такие деревья затем предполагается использовать для нахождения событий совместной эволюции регионов генома, что может говорить об эпистатических взаимодействиях генов.
Поиск генетических факторов осложнений беременности | Институт биоинформатики

студент: Царев Александр
руководители: Барбитов Юрий, Скитченко Ростислав
Проект посвящен расшифровке генетических механизмов осложнений беременности. В данной работе мы воспользуемся публичным набором данных UK Biobank (http://www.nealelab.is/uk-biobank). Мы попробуем не только определить наборы значимых маркеров изучаемых фенотипов, но и сделать глубокую функциональную аннотацию результатов и сравнение с результатами других исследований (например, NHGRI GWAS Catalog).
Генератор неразрешимых неоднозначностей (roi_amb_analyzer tool) | Parseq Lab

студент: Толмачев Михаил
руководители: Симакова Тамара, Мозгов Сергей
HLA-типирование является необходимым этапом при подборе доноров для трансплантации органов и тканей. HLA - это белки, расположенные на поверхности клетки, обеспечивающие презентацию фрагментов антигенов иммунным клеткам. Разнообразие этих молекул крайне велико, все известные аминокислотные и нуклеотидные последовательности молекул HLA содержатся в специализированной базе данных IMGT HLA, насчитывающей на данный момент около 24 000 вариантов генов HLA. HLA-типирование осуществляется за счет NGS-секвенирования и последующего выравнивания прочтений на базу данных. При этом различные тест-системы покрывают различные регионы генов HLA, в результате чего возникают естественные ограничения метода, связанные с тем, что часть аллелей невозможно дискриминировать по причине того, что различия между ними находятся в непокрытых тест-системой регионах. Выявление таких ограничений является необходимым этапом верификации тест-систем, которую требуется проводить каждый раз после ежеквартальных обновлений базы данных.

Целью проекта является создание инструмента для выявления ограничений тест-систем для HLA-типирования (roi_amb_analyzer tool).
Deep Learning for 3D Molecular Interactions | Skoltech

студенты: Кузнецов Игорь, Ефимов Егор, Глубоков Дмитрий, Ковалев Александр

руководители: Попов Петр
Molecules constantly interact with each other, maintaining integrity and functionality of living organisms. Broken molecular interactions typically lead to serious diseases, such as cardiovascular, neurodegenerative diseases, cancer, and others. Nowadays, there is a great need in more efficient, specific and safer drugs that modulate molecular function via atomic interaction. In order to design a chemical with desired modulation activity one needs to known molecular interactions in atomic details. Experimental techniques, such as X-ray crystallography, NMR, and Cryo-electron microscopy are used to determine spatial structures of molecular complexes on sub-nanometer scale and, hence, allow to look at molecular interactions in atomic details. With the growing number of structural information about molecular complexes and powerful computational resources, it is now possible to develop new generation of structural bioinformatics approaches using state-of-the-art machine learning methods.
Deep learning approach to determination of local ancestry | Университет Ла Верне

студенты: Веселова Влада, Сметанин Александр
руководитель: Татьяна Татаринова
Большинство людей живущих сейчас на Земле имеют смешанное происхождение. У кого-то есть всего лишь небольшая примесь, кто-то - сплошная мозаика из разных этнических групп. Современные методы определения происхождения хорошо работают для ограниченного набора сценариев смешения. Методы машинного обучения - это новая и многообещающая область, позволяющая эффективно решить эту задачу для всех сценариев.
Поиск адаптаций к повышенному содержанию кислорода у байкальских организмов с помощью данных об экспрессии генов | НИИ биологии ИГУ

студенты: Киркилевич Анна, Долгих Александра
руководитель: Дроздова Полина
Кислород необходим для жизнедеятельности практически всех живых организмов, но его избыток опасен, поскольку нарушает равновесие окислительно-восстановительных процессов. Вода озера Байкал насыщена кислородом в значительно большей степени, чем многие другие пресноводные водоёмы. Следовательно, длительно существующая в озере фауна могла эволюционно приобрести адаптации к высокой концентрации растворённого кислорода в течение всего года. В рамках проекта предлагается прицельно изучить различия в системе антиоксидантной защиты байкальских видов амфипод (литоральные виды Eulimnogammarus verrucosus и E. cyaneus) и родственного им вида Gammarus lacustris, который обитает в других водоёмах региона, но не образует стабильных популяций в открытом Байкале.
Анализ структуры популяции по данным секвенирования РНК | НИИ биологии ИГУ

студент: Глушкевич Анна
руководитель: Дроздова Полина
Разнообразие особей внутри популяции — показатель, по которому можно судить о происходящих микроэволюционных событиях. Обычно для анализа генетического материала популяций животных используют секвенирование амплифицированных фрагментов митохондриальных (COI) или ядерных (18S) маркерных генов. Информацию об этих последовательностях можно получить и из данных секвенирования нуклеиновых кислот методами NGS. В этом проекте мы сравним разнообразие последовательностей маркерных генов, полученные с помощью разных способов секвенирования для особей одной и той же популяции байкальского эндемичного вида амфипод Eulimnogammarus verrucosus.
Филогенетический анализ как инструмент криминалистики | Университет ИТМО

студент: Поденкова Ульяна
руководитель: Алексеев Никита
В последние несколько лет биоинформатика находит себе все новые применения в forensic sciences. В частности, в случаях вспышек вирусных заболеваний, важным вопросом является "кто кого заразил", на который можно ответить с помощью филогенетического анализа штаммов вирусов, найденных у разных пациентов. В рамках проекта предполагается сделать обзор существующих методов и алгоритмов, и, возможно, поучаствовать в разработке новых методов. На проекте уже есть команда из программистов, но присутствие биолога помогло бы сделать нашу деятельность более полезной.
Иммуносупрессивные домены в геноме человека | yRisk

студенты: Мураева Ольга, Поздняков Данила, Панков Викентий, Рапота Диана, Охтиенко Анастасия
руководители: Афанасьев Андрей, Ступников Алексей
Идентификация иммуносупрессивных доменов (ISD) в геноме человека, гомологичных ретровирусным.
Молекулярная мимикрия ВИЧ | ИБХ РАН

студенты: Харламов Владислав, Овсянникова Александра, Кравец Андрей

руководитель: Цветков Василий
Проект нацелен на изучение свойств вируса иммунодефицита человека и его эволюцию в течение срока инфицирования организма. Было показано, что частицы вируса мутируют с высокой скоростью, изменяя молекулы в своём составе таким образом, чтобы избежать иммунного ответа со стороны организма хозяина. В связи с этим было бы интересно показать на данных глубокого и лонгитюдного секвенирования вирусных частиц у больных СПИД, как изменяются физикохимические характеристики поверхностных белков вирусных частиц. Также можно попробовать натренировать классификатор, который позволил бы предсказывать последствия конкретных мутаций вирусного генома.
Участие бактериофага в горизонтальном переносе прокариотических генов в геномы эукариот | Институт Цитологии РАН

студент: Грецова Мария
руководитель: Даугавет Мария
Передача генов из генома одного организма в геном другого неродственного организма называется горизонтальным переносом генов (ГПГ). На сегодняшний день описаны случаи ГПГ из генома прокариот в геном эукариот для большого числа организмов, однако, механизм этого процесса неизвестен. Для асцидий, одной из групп примитивных Хордовых животных, описано два случая ГПГ от прокариотических организмов. Один из них это приобретение гена целлюлозо-синтазы от бактерии Streptomyces sp., описанный Накашима с соавторами (Nakashima et al., 2004). Другой, для асцидии Styela rustica, был описан в нашей работе (Daugavet et al., 2019). Белок асцидии S. rustica, рустикалин, содержит два структурных домена, при этом кодирующая область C концевого домена имеет достоверное сходство с ферментом карбоксипептидазой, описанной ранее только для бактерий и бактериофагов. Как для С концевого домена рустикалина, так и для каталитического домена целлюлозо-синтазы было показано, что их кодирующие области лежат в геноме рядом с потенциальным сайтом встраивания бактериофага - AttP. Таким образом, возможный механизм ГПГ может задействовать бактериофага в качестве вектора переноса генов из генома прокариот в геном эукариот.
Мы предполагаем, что последовательность сайта встраивания бактериофага может помочь обнаружить новые случаи ГПГ в геномах эукариотических организмов. Однако, длина сайта встраивания бактериофага AttP составляет всего 43 нуклеотида, что слишком мало, чтобы достоверно обнаружить его в больших базах данных. Тем не менее, мы знаем, что в гене гомолога рустикалина AttP-подобный сайт расположен внутри интронов N концевого домена. Основываясь на этом, мы провели поиск отдалённых гомологов (HMMER) с использованием аминокислотной последовательности N концевого домена. Последовательности, схожие с N концевым доменом, обычно являются частью более крупных белков. В составе этих белков так же присутствую известные консервативные домены. Несмотря на то, что найденные белки почти исключительно эукариотические, консервативные домены, входящие в их состав (в 98 белках из 124) являются доменами, которые в соответствии с базой данных Pfam типичны для прокариот или бактериофагов. Было идентифицировано девять различных доменов, которые можно классифицировать как бактериальные ферменты, гидролизующие клеточную стенку. На основании этих наблюдений можно сделать вывод, что последовательность схожая с N концевым доменом в эукариотических белках обычно сопровождается типичными прокариотическими доменами. Мы предполагаем, что найденные эукариотические последовательности могут иметь химерное происхождение и некоторые их консервативные домены образовались в результате ГПГ от прокариотических организмов.
Цель проекта:
Подтвердить химерное происхождение найденных последовательностей, содержащих домены типичные для прокариот или бактериофагов.
Effect of the proteomic sample pooling on statistical power and type I error rate | СПбГУ

студенты: Гурина Алёна, Озерова Юлия
руководители: Данилов Лаврентий, Варфоломеева Марина
Протеомные исследования часто проводят с применением пулированных образцов. Пулирование проб - это смешивание биологического материала от разных особей. В результате уровень экспрессии большинства белков в пуле будет равен среднему уровню экспрессии соответствующих белков в отдельных образцах. В результате пулирования увеличивается общее количество биологического материала в пробе, что бывает особенно важно при исследовании мелких организмов. Кроме того, при пулировании увеличивается качество сопоставления пятен белков на разных гелях. Наконец, снижается уровень биологической изменчивости между отдельными пулами, и это, в свою очередь, влияет на мощность статистических тестов. В ходе предполагаемого проекта предлагается оценить как влияет число и размер пулированных проб на мощность статистических тестов при разном уровне биологической и технической изменчивости в анализе дифференциальной экспрессии.
Черная кошка в тёмной комнате: поиск новых вирусов и плазмид в метагеномах | Центр Алгоритмической Биотехнологии, СПбГУ

студенты: Калтович Артём, Яковлева Юлия, Сказина Мария, Забелкин Алексей
руководители: Райко Михаил, Антипов Дмитрий
На сегодняшний день в базах данных лежит много собранных метагеномов, которые проанализированы довольно поверхностно. По последним работам стало ясно, что мы очень сильно недооцениваем разнообразие вирусов и плазмид - например, самый распространенный бактериофаг в кишечнике человека был открыт только в 2014 г, а в 2017 было показано, что это на самом деле целая группа родственных вирусов (причем всё это было обнаружено исключительно биоинформатическими методами). В данном проекте мы предлагаем поискать новые вирусы и плазмиды в доступных метагеномах из различных сред с помощью инструментов, разработанных в нашей лаборатории.
Динамика разнообразия и обилия симбионтов в метагеноме | НИИ биологии Иркутского государственного университета

студент: Алексеева Лолита

руководитель: Дроздова Полина
Общее описание проекта.
Данные для анализа: около 60 образцов RNA-seq (~30 млн. парных ридов на образец, Illumina 2x100), для каждого образца использован материал
одного целого животного вида Eulimnogammarus verrucosus (Crustacea:
Amphipoda). Около половины образцов соответствуют животным,
содержавшимся в контрольных условиях, а остальные — животным,
подвергнутым влиянию различных стрессоров. Согласно предварительным данным, существенное число чтений принадлежит симбионтам или комменсалам объекта исследования, в первую очередь инфузориями.

Цели проекта: характеристика разнообразия симбионтов в транскриптоме
разных особей и изучение стабильности состава (и количественного
соотношения) симбионтов между разными особями одного вида и при
стрессовых воздействиях.
Где в персике спрятался ретротранспозон? | ИОГен РАН

студенты: Пахалко Илья, Гончар Анастасия

руководитель: Поверенная Ирина
Ретротранспозоны - это генетические элементы, которые могут самовоспроизводиться и путешествовать по геному. Хотя они есть в большинстве эукариотических организмов, больше всего их можно найти в геномах растений. Семейство Розоцветные (Rosaceae) включает в себя много ценных плодовых деревьев (яблоко, груша, персик и т.д.), и выведение новых сортов на сегодняшний момент требует большего понимания генетического разнообразия как в отдельных видах, так и во всем семействе. Поскольку каждая миграция ретротранспозона в новое место является эволюционным событием, по их месторасположению в геномах представителей Розоцветных можно будет оценить эволюцию данного семейства.
Обработка данных LCMS | Skoltech

студенты: Машкова Ольга, Хамитов Денис, Недильченко Ольга, Синяков Артем

руководитель: Ильин Александр
Есть данные липидомного анализа из исследования по влиянию витамина Д на мышей. Целью проекта является обработка и интерпретация данных.
Обмен транспозонами в геномах вагинальных бактерий | ФХМ ФМБА России

студенты: Мазур Ольга, Янушкевич Сергей, Попова Аделия

руководитель: Старикова Елизавета
Вагинальная микробиота представляет собой относительно закрытое микробное сообщество, представленное, как правило, несколькими видами лактобактерий, которые поддерживают кислотную среду, необходимую для нормального функционирования женского организма. Мы предполагаем, что данная экологическая ниша также создаёт благоприятные условия для горизонтального переноса генов, в том числе между лактобактериями и условно-патогенными микроорганизмами. Один из наиболее интересных путей горизонтального переноса генов (например, генов устойчивости к антибиотикам) -- с помощью бактериальных транспозонов.
Цель проекта -- идентифицировать общие транспозоны и переносимые ими гены в геномах различных вагинальных бактерий.
Научные проекты 2018/2019
С основными результатами проектов можно ознакомиться в тезисах.
Осень 2018
Весна 2019
Лето 2019
Study spectrum of genetic variants in TTN gene | Federal Almazov Medical Research Centre

students: Olga Lebedenko
scientific adviser: Artem Kiselev

The TTN gene with 363 coding exons encodes titin, a giant muscle protein spanning from the Z-disk to the M-band within the sarcomere. Titin has roles in assembling and maintaining sarcomere structure, flexibility, stability, stretch and force transmission. Mutations in the TTN gene have been associated with various cardiomyopathies.

The main aim of this study was to investigate spectrum of genetic variants in TTN gene within group of patients with cardiomyopathy. 151 different type of cardiomyopathy samples, sequenced with Haloplex custom targeted capture, were processed with SNP Calling pipeline implemented on Snakemake and annotated by snpEff. Among 418 discovered SNP 64.44% variants were missens and 35.56% variants were silence. The PCA analysis showed absence of clustering SNP by type of cardiomyopathy. Fisher's exact tests with Bonferroni correction were used to compare allele frequencies of observed variants against all gnomAD population. Pathogenicity of 12 discovered statistically meaningful missense variants was predicted by algorithms SIFT, PolyPhen-2, Mutation Assessor, Provean and I-Mutant 3.0.

Almost all variants showed neutral effect on protein structure and stability. The most interesting SNP was the mutation rs9808377 I62T, presumably affecting on stability of the subunit Fn3-102 titin by I-Mutant 3.0. Presumably, this result may be explained by difficulties in multiple comparison connected with a high rate of spontaneous mutation owing to enormous size of TTN gene. Another reasons in analyzing accompanying TTN variants in cardiomyopathy group with confirmed well-knowing causative mutations.

Slides
A library of functions for express analysis of FASTA/FASTQ files | Bioinformatics Institute

students:
Alena Kizenko, Alisa Morshneva, Polina Pavlova
scientific adviser: Eugene Bakin

Frequently, when carrying out bioinformatics projects including FASTA/FASTQ files processing, one has to solve routine tasks, e.g. deduplication of sequences. A common approach for this is writing little scripts in Python/bash or dealing with existing programs, which may be complicated for usage. Therefore, we decided to create a flexible tool containing functions for processing files with sequencing data. We created a program called BreakFAST which is based on Python 3 and the following libraries: Biopython, argparse, pandas, numpy, matplotlib and re. The tool consists of three modules. Basic statistics module can be used for counting:

● minimum, maximum, mean, total length of reads;
● GC-content;
● quality scores;
● N bases.

Filtering module can be used for deleting:
● reads shorter than X;
● reads containing Ns;
● poor quality reads;
● duplicates;
● reads with a particular motif.

Matching module can be used for:
● joining reads from files;
● finding overlapping between files;
● subtracting sets of reads from files.

While applying commonly suggested Biopython functions we've faced performance problems while parsing a large volume of data. For mitigation of this effect while iterating over FASTA/FASTQ files, we compared SeqIO.parser and Iterator from Biopython. We have found that usage of Iterator in Filtering and Matching modules was optimal for iteration (10 times speed gain). Notably, we compared function "delete reads shorter than X" with the same Trimmomatic's function and found that BreakFAST occupies up to 7 times less RAM, which may be useful when a computer`s capacity is limited. As a result, BreakFAST is a simple and customizable tool, which can be potentially updated with new modules and functions.

Slides
Visualization of signaling pathways basing on genes differential expression profile | First Pavlov State University of St. Petersburg

students: Stanislav Legkovoy, Olga Romanova
scientific advisers: Eugene Bakin, Oksana Stanevich

In recent years, Gene Expression Omnibus (GEO) NCBI database has accumulated a significant amount of data obtained via mRNA microarrays, which are widely used for an analysis of differential expression profile. During a research of genes expressions, a proper visualization of results is an important task. One of the best ways is to use R language and related packages for statistical analysis, preprocessing and visualization of expression data through interaction with KEGG database.

An aim of this study was to visualize signaling pathways according to the gene expression data obtained from GEO NCBI database. To achieve our goal, we implemented an easy-to-use script based on pathview, gage and GEOquery packages, which allowed us to obtain gene expression data directly from the GEO NCBI database and to find the most significant signaling pathways from KEGG PATHWAY. Using the developed script, we analyzed the Affymetrix microarray data, identified and visualized the most significant signaling pathways involved in reprogramming of lymphatic endothelial cells infected by human Kaposi's sarcoma-associated herpesvirus (KSHV).

Slides
Comparative analysis of NUMT in underground and terrestrial rodents | Zoological Institute RAS

students: Ekaterina Sytnik
scientific adviser: Olga Bondareva

NUMT (nuclear mitochondrial DNA segment) is a transposition of mitochondrial DNA into nuclear genome. They are found in all eukaryotes but significantly differ in length and number among different species. Particular factors that can be associated with NUMTs are still not determined. Due to the specificity of mitochondrial genes, habitat conditions may be one of the factors.

They aim of this study was to estimate the number of NUMT for underground and terrestrial rodents. For this work we only analyzed long (>300 n.p.) NUMTs of protein- coding regions. We used Genbank database for mitochondrial and nuclear genomes (4 species for each group) and BLAST for NUMT searching. It was found that some genes like ND4L and ATP8 are not likely to be included in NUMTs, which may be caused by the small size of the genes. Some underground species are shown to have a larger amount of long NUMTs but it is yet unclear if the same is true for whole group.

Further study should include larger amount of species and dN/dS analysis for each gene to determine whether some of the NUMTs may have a functional role.

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The comparative analysis of MDR Klebsiella pneumoniae genome | Children's Scientific and Clinical Center for Infectious Diseases

students: Anastasia Kapanina, Nina Lukashina, Daria Likholetova
scientific advisers: Eugene Bakin, Oksana Stanevich, Sergey S. Sidorenko
Klebsiella pneumoniae is a gram-negative bacteria that is known as opportunistic, hypervirulent, and multidrug resistant hospital pathogen. The problem of resistance to carbenemase group of antibiotics makes it one of the main threats during hospitalisation. The diversity of K. pneumoniae is studied by whole-genome sequencing (WGS) and multiple typing methods including multi-locus sequence typing (MLST), that separate strains into different lineages. In our study we assembled and analysed genomes of 22 isolates of different years and sources from the Saint-Petersburg hospitals to identify their origin and describe their pangenome.

With use of Kleborate tool, we found that our strains belong to common european and asian MLST types (ST147, ST11, ST340 and ST395). All of them carry NDM-1 and ParC resistance genes, and only one - OXA-48. According to the genes discovered in strains, we listed inefficient antibiotics for their treatment. Via PlasmidFinder we detected a presence of plasmid R27 of Salmonella typhi, that can be explained by contamination of samples or by horizontal transfer between K.pneumoniae and S. typhi.

According to an existing literature, the obtained MLST types are spread in Europe and Asia. However, for obtaining a more detailed result about an origin of the strains, a genome structure analysis is needed. In conclusion, we can say that within the period from 2012 to 2016 there were no invasions of new sequence types on a territory of mentioned hospitals. The obtained results of pangenome analysis can be used in treatment prescription.

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Comparative analysis of the human pathogens genomes Neisseria meningitidis | Children`s Scientific and Clinical Center for Infectious Diseases

students: Anton Matiiv, Ilia Sheshukov
scientific advisers: Eugene Bakin, Oksana Stanevich, Sergey S. Sidorenko

Neisseria meningitidis or meningococcus often colonizes the mucous membrane of the oropharynx, causing no visible symptoms, but is also the main cause of bacterial meningitis and sepsis throughout the world. The epidemiological profile of N. meningitidis varies in different populations, and over time, the virulence of meningococcus is based on the plastic genome and the expression of certain capsular polysaccharides and non-capsular antigens. Twelve different serogroups based on the polysaccharide capsule have been identified, but only six of them (A, B, C, W, X and Y) account for 90% of the invasive meningococcal disease worldwide. Seven housekeeping genes for meningococcal strains are used for MLST (multilocus sequence typing) to determine their sequence types (ST).

The aim of our work was to compare whole genome sequencing data of 20 Neisseria meningitis samples isolated from carriers and sick people, to use phylogenetic analysis and to find a connection with antibiotic resistance, virulence and carriage.

Before the analysis of sequences, we have written a computer script for interfacing and downloading reference genomes from NCBI. We analyzed the antigen-encoding, virulence and carriage associated and antibiotic resistant gene profiles. We also searched for amino acid changes leading to penicillin resistance. To estimate the relationship between samples, phylogenetic trees were constructed on the basis of isolates assemblies by using CSI Phylogeny and REALPHY. We constructed phylogenetic trees for carriage associated genes to figure out if the samples would cluster according to their origin of isolation.

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Finding of cis-regulatory elements in promoters | University of La Verne

students: Daria Balashova, Elena Polyakova
scientific adviser: Tatiana Tatarinova

We consider a genome-wide statistical approach for the detection of specific DNA sequence motifs based on similarities between the promoters of similarly expressed genes. A comprehensive landscaping of major regulatory motifs can contribute to understanding molecular mechanisms of many complex diseases.

Assuming position-specificity of the function of promoter motifs, providing gene expression data of reasonable measurements of the number of transcripts and reflecting of the activity of the promoter, we develop cisExpress software that includes the algorithm for finding statistically significant associations between words of defined length with respect to the transcription start site in the expression dataset. Subsequent optimization includes combining motifs that have small differences and clustering basic words of fixed size into larger composite motifs. The analysis of time series, conducted on the basis of Hidden Markov Models, allows us to observe the significance of the found motifs over time. The tool is complemented by interactive graphical representations.

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Analysis of the Drosophila melanogaster full genome sequences | EPAM Systems, Lifesciencs department

students: Anna Namyatova
scientific adviser: Gennady Zakharov

Drosophila melanogaster is a model object for studying insect genomes. The results can be used to make prediction on the human diseases. We had the Illumina full genome sequences for two wild type lines and two mutant lines (ts3 and X1). In the ts3 line, the defects were artificially induced with the behaviour being restored to normal after the thermal shock. The defects in the line X1 were spontaneous and permanent. The aim was to compare the mutant line genomes with each other and with those of the wild type lines, and find the genes responsible for the abnormalities in the nervous system structure and function. We used the following tools for our analysis:

1. FastQC. Sequences quality check.
2. Trimmomatic Trimming the bad quality nucleotides.
3. Bwa. Genome assembly.
4. Samtools. Creating, sorting and indexing the .bam file.
5. Picard. Adding the Readgroups into .bam files.
6. Gatk. Variation calling.
7. Vcf-merge. Merging the wild type lines mutations.
8. Rtg vcfeval. Comparing the each mutant line mutations with those in the wild type
lines.

The genomes were mapped against the reference genome Drosophila_melanogaster.BDGP6.dna_sm.toplevel.fa. FastQS showed that there were around 30 million reads in each genome, the length of reads ranges between 35 and 76 bp in the raw sequences. The total number of mutations in the wild type line was 1209056. Each mutant line had around 800000 mutations. There were 195743 unique mutations in the ts3 line, and 174653 unique mutations in the X1 line. In the future we are going to perform snpeff and snpsift tools to annotate the mutations, to assign the biological meaning to them and to exclude the nonsense mutations.

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Transcriptional response of pea roots to symbiosis markers | All-Russia Research Institute for Agricultural Microbiology

students: Varvara Tvorogova
scientific advisers: Polina Kozyulina, Elena Dolgikh

Root nodules in legumes are symbiotic organs hosting nitrogen-fixing bacteria. At the beginning of the formation of nodule, bacteria enter the intercellular space of the root; therefore, the host plant needs an accurate recognition system that allows it to let symbiotic bacteria pass inside its tissues and block parasitic organisms from doing the same. The main external signals that provide such recognition are chitooligosaccharides of different lengths. Thus, chitooligosaccharides consisting of five monomers (co5) are markers of symbiotic bacteria, while chitooligosaccharides consisting of eight monomers (co8) are markers of parasitic organisms (insects and fungi).

The purpose of this study was to analyze the data of MACE-sequencing of pea (Pisum sativum) RNA from roots pretreated with co5 or co8 chitoligosaccharides. Using the pea nodule transcriptome obtained previously (Zhukov et al., 2015) and the Dedupe software from BBTools package, we removed ambiguous transcripts and got the optimal reference transcriptome for our data. Then, using the DESeq2 and GSEABase packages, we analyzed differential gene expression in our samples and performed gene enrichment analysis. According to the results obtained, co5 treatment shows more prominent differential gene expression compared to co8 probably due to incomplete reference transcriptome. However, both co5 and co8 chitoligosaccharide treatments activate gene sets that are responsible for parasite-host interaction, chitin binding and cleavage, as well as numerous signaling pathways which include different phytohormones, receptor kinases and transcription factors.

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Modeling of mouse chromosome banding pattern | Bioinformatics institute

students: Yury Lebeda
scientific adviser: Yury Barbitoff

Differential chromosome staining is a method of chromosome staining with special dyes to detect certain discs or regions of the chromosome (also called chromosome bands). The resulting banding pattern is an important marker of genome architecture; however, no specific molecular determinants of it are known to date. Previously, our group discovered the relationship between the pattern of differential staining of chromosomes and several genomic features (ChIP-Seq tracks of Smc1a/Smc3, CTCF, polyA and polyT repeats). However, when validation of this relationship using the genome of Mus musculus was attempted, it was found that the distribution of genomic elements within the M. musculus bands differs from that observed in humans. In this project, we took an effort to develop a model that would be able to predict the border regions between bands, on the basis of the human genome data, and apply this model to predict the banding of M. musculus chromosomes.

We built a random forest model to predict the borders of the bands based on the number of genomic elements (i.e., ChIP-Seq peaks or k-mers) lying in the intervals of a given width inside and outside of the band borders. For prediction, the M. musculus genome was cut into intervals of the same width by a sliding window; and the resulting intervals were annotated with the same features that were used to train the model. Unfortunately, all the models constructed (despite high cross-validation AUC scores) failed to provide reasonable predictions – both for the mouse and human genomes, the results of the prediction of band boundaries differed from the already existing markup. The results can be explained by a large number of false-positive results, which becomes significant even with a small false-positive rate at large numbers of trials. Hence, a new model has to be sought for to explain the nature of chromosome bands.

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De novo assembly and analysis of Platynereis dumiliii (Nereididae, Annelida) transcriptome
at different stages of regeneration
| Saint-Petersburg State University

students: Natalia Zenkova, Ruslan Abasov
scientific adviser: Maxim Nesterenko

Regeneration – the regrowth or repair of cells, tissues and organs – is widely but non- uniformly represented among all animal phyla. However, the potency of its highly variable even within a single group. The object of this study is the polychaeta Platynereis dumerilii (Nereididae, Annelida), capable to recover only tail. RNA-seq data of different time points after amputation (0, 4, 12, 24 hours, 2 and 4 days) from "head" and "tail" sites of regeneration were analyzed. Libraries of corrected read pairs (Karect, Trimmomatic, BBtools) were used to the de novo assembly of reference transcriptome (Trinity).

The resulting assembly was characterized by high quality (TransRate-score = 0.2441) and completeness (BUSCO vs Metazoa-odb9 = 99.5%). The amino acid sequences predicted by TransDecoder (N = 160381) were compared to the Swiss-Prot database using the Diamond (e-value = 1e-10). More than 61% of the sequences were successfully annotated, but among the sequences without hits we assume the presence of species-specific proteins. Based on the normalized expression levels analysis results (Salmon), sets of "associated" sequences were highlighted for each of the samples. We suggest that incomplete overlap between "associated" sets both between time points and between sites indicate complex dynamics of gene activity during postamputation events. However, expression patterns of regeneration conservative genes (for instance: Piwi-, Vasa-, Wnt- and Notch-like) varies slightly between "head" and "tail" sites. Based on the results obtained, it can be assumed that cell proliferation is not over on 4 days after amputation and damaged structure recovery will be observed at later stages of generation.

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Analysis of nonsense alleles of Caenorhabditis elegans genes | Lomonosov Moscow State University

students: Daria Chaplygina
scientific adviser: Nadezda Potapova

Nonsense mutation in gene is a mutation that results in a premature stop codon. Most of genes with nonsense alleles translates into a nonfunctional proteins, which makes such genes to be a pseudogenes. The purpose of this study was to analyze the distribution of nonsense mutations in Caenorhabditis elegans genes and to perform a direct measurement of the strength of negative selection acting on nonsense alleles. For the measurement we counted the average ratio of the number of nonsynonymous mutation to the number of synonymous mutations for each gene (pN/pS ratio). The obtained pN/pS ratio then was compared to the pN/pS ratio in genes without nonsense mutations. Genome sequences processing was performed by SAMtools, VarScan and SnpEff.

According to the obtained results, the most of synonymous mutations are located at the 3′-end of gene, where they are less harmful. Also it was shown that nonsense alleles, common for many species in population, are rare, which must be due to negative selection against them. The average pN/pS ratio appears to be about 1 for genes without nonsense alleles and slightly more than 1 (1.2) for genes with nonsense alleles. Such results means that negative selection does not act on any gene, which can not be true. The mistake could be explained by possibly wrong variant annotation.

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Prioritization of genetic variants | Bioinformatics Institute

students: Vasiliy Isaev, Liubov Lonishin
scientific adviser: Yury Barbitoff

The identification of deleterious mutations within candidate genes is a crucial step in the elucidation of the genetic bases of human disease, consequently, there is a need to aim attention at classifying appropriate mutations. The goal of our programme, which is called MutationsPriorityPredictionTool (MPPT) is to find out these genetic variants from thousands of others in order to help clinicians and geneticists.
To calculate the coefficient we have developed an tool. Tool get on input vcf-file and set of simple configurations that contain rules on how to calculate mutation priority score depends from parameters given in the file. After calculating tool will print top of mutation by parameter specified by user. It can be top 10% of mutations or 100 mutations ot other option. We have tested our programme on whole exome sequencing data, obtained from the resource centre. First of all, the selection of the test sample was made in accordance with the ClinVar database and was compared with results of Franklin, which is based on ACMG recommendations (The American College of Medical Genetics and Genomics). The percentage number of correct calls by MPPT was calculated, and the sensitivity and specificity of the method was determined. Accuracy of our programme is 67,5%, sensitivity is about 100% (95% CI = 79.4% to 100.00) and specificity is 60,6% (95% CI =53.9% to 67.3%). Testing on the whole data, we obtained 114 mutations above the threshold from more than 22 thousand at all.

MPPT focuses on pathogenic variants without losing them, but also keeps some benign variants which should be manually checked by a specialist after running. In the future, we will add this functionality to NGB (New Genome Browser).

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Assembly of yeast genome with Oxford Nanopore data | Bioinformatics Institute

students: Andrew Matveenko
scientific advisers: Yury Barbitoff, Alexander Predeus

Baker's yeast Saccharomyces cerevisiae is a widely used model organism. The Peterhof genetic collection (PGC) is a large laboratory stock unrelated to the yeast reference strain. Previously, several PGC strains were sequenced using Ion Torrent technology. However, the resulting assemblies were incomplete and required substantial improvement. We attempted to obtain a reference quality assembly of one PGC strain, 1A-D1628, using Oxford Nanopore Technology (ONT) sequencing.

Raw data was obtained from one ONT MinIon flowcell which generated 10.15 Gbp total sequence length (836x coverage). To create draft genome assembly we used three long-read assemblers: Canu, Flye and wtdbg2. Canu produced the best results, with 17 large (> 50 kbp) contigs that correspond to 16 yeast chromosomes and mitochondrial DNA. Flye was slightly worse with 18 large contigs as it failed to assemble chromosome III as a single molecule. Wtdbg2 failed to produce any sensible sequence. Comparison of the Canu assembly with the reference showed that it contained 105 misassemblies, and large amount of mismatches and short indels. We also analyzed structural variations in the strain using NGMLR-Sniffles pipeline. The results of analysis were concordant with variations described previously in 1A- D1628.

In conclusion, the data obtained from the Oxford Nanopore sequencing can be used to analyse structural variations in the 1A-D1628 strain. However, the de novo assembly requires additional correction and polishing to reach the reference quality. Several strategies can be used to achive this goal. First, an alternative basecaller can be used to improve the quality of reads. Second, exclusively for ONT, the assembly can be improved by polishing with the MinIon raw signal using Nanopolish tool. And finally, polishing the assembly with the obtained Illumina reads should improve the accuracy of the sequence producing high quality reference, which can be used for comparative genomic studies.
The work is supported the RSF grant 18-14-00050.

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The study of processes of gene gain and loss within Lactobacillus species | Zoological Institute RAS

students: Anastasia Kosolapova
scientific adviser: Olga Bondareva

Lactobacillus genus includes Gram-positive non-sporulating bacteria known for their ability to produce lactic acid as a result of carbohydrate fermentation. To date more than 180 species refer to Lactobacillus genus. A hallmark of that genus is a high level of intra-group diversity. Firstly, the diversity exhibits in ecology of the group as lots of Lactobacillus species are associated with cavities of human and animals, for example gastrointestinal tract and urogenital tract, while others can be found on plants, in dairy and fermented products. Secondly, the genome size of Lactobacillus bacteria can vary between 1.2 Mb and 5 Mb.

The aim of this work was to study connection between ecological specificity and genome organization within various strains of Lactobacillus and analyze influence of ecological specificity on processes of gain and loss of genes. As a data for analysis we used protein and CDS sequences for 185 Lactobacillus species (1708 strains) from RefSeq database. Lactococcus lactis subsp. lactis Il1403 protein and CDS sequences were used as an outgroup. We classified species into 7 groups based on ecological niche. We revealed orthologous proteins within strains using Proteinortho5/POFF software. Further research should involve a phylogenetic tree reconstruction based on full orthologous genes groups followed by gain-loss analysis performed with GLOOME software.

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Detection of interchromosomal rearrangements from Hi-C data | ITMO University

students: Elena Kartysheva, Dmitriy Orekhov
scientific adviser: Nikita Alexeev

Chromosomal rearrangements disturb complex 3D structure of eukaryotic genome and may lead to various disease among which is cancer, detecting them may be useful in early diagnostics. Hi-C is a relatively recent sequencing method that estimates 3D proximity between different regions of a sequenced genome, this type of data allows for detection of different chromosomal abnormalities. We have developed an algorithm that scans through Hi-C map and reports the presence of interchromosomal rearrangements with the coordinates of their breakpoints. The algorithm relies on 2D convolution and GMM for filtering out the data and detection of interchromosomal interactions, then a sliding-window approach is used for breakpoint localization. The method is tested on Hi-C maps obtained from glioblastoma cells of H.Sapiens, showing both high precision and high recall.

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Plasmid host range prediction based on CRISPR arrays. Plasmids CRISPR Cas systems search. | CAB SPbU

students: Mikhail Kongoev, Iana Fedorova
scientific adviser: Mikhail Rayko

Horizontal gene transfer plays a highly important role in evolution of bacteria. Presumably, gene exchange between bacteria occurs by genetic mobile elements such as plasmids and bacteriophages. But for nowadays there is no reliable way to check if the certain plasmid can "travel" between bacteria of different origin, and how wide the plasmid host range could be. Also it is important to be able to predict plasmid host in case of metagenomic data, where we usually have dozens of novel plasmids without any information of host species.

To answer this question, we analyzed CRISPR cassettes in bacterial genomes – repetitive sequences in bacterial DNA, interspaced with unique "spacer" sequences, which were extracted from genetic mobile elements infected the bacteria or its ancestors. Spacers in CRISPR cassette can be considered as a link between the plasmid and its host.

We used CRISPR Finder spacers database and the RefSeq database of all plasmids known to date (November 2018). Blasting spacers over plasmids sequences allowed us to determine plasmid host ranges: variety of bacterial organisms where the plasmid can exist. By taxonomy analysis we found some plasmids which can live in different families of organisms, they can be useful in genetic engineering as a natural shuttle vectors. Taxonomy analysis showed that a bunch of plasmids have additional hosts except of host they were related to according to RefSeq database: 543 blast hits – additional hosts of different genus, 29 blast hits - different family, 19 - different order, 12 - different class and even 2 blast hits – additional hosts of different phylum! Thus, plasmids are actually "travelling" between bacteria species and can be important players in process of evolution.

We also found, that a lot of plasmids carry their own defense CRISPR systems (10% of RefSeq plasmids). Part of these systems (10%) seems to be active – there are Cas1 genes near CRISPR cassettes. Role of these systems in plasmid propagation, host fitness and evolutionary relationship with the known chromosomal CRISPR-Cas systems is the subjects of future research.

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Automated pathway annotation for single-cell RNA-seq | Washington University in Saint Louis / ITMO University

students: Maria Firuleva
scientific adviser: Konstantin Zaitsev

Method of single-cell RNA-seq expands the opportunities to research a biological difference between cells of interest by the individual transcriptome analysis of each cell simultaneously and to study the cell's processes more deeply. Increasing pace of RNA-seq methods expects automated approaches to process a huge amount of that data. Different cell processes are mediated by a different set of genes (signal pathways), and expression of appropriate genes changes due to activation or deactivation of appropriate signal pathways. The main target of this project is to develop a method for automated annotation of pathways which are significantly upregulated in the single-cell dataset.

We developed a three-step approach to identify differentially expressed pathways, which is applied after performing the usual single-cell rna-seq pipeline using Seurat package. First, we calculate how each pathway is expressed in every cell. Second, randomly sampling gene sets we identify candidate cells that in which pathways are upregulated more than at random. Third, we identify clusters in which there are more candidate cells than at random, using hypergeometric distribution. As a result, our program returns a matrix with cell clusters as columns and pathways as rows which values are adjusted p-values. Developed approach combined with cumulative statistic approaches allows to quickly find significantly upregulated pathways in a single-cell dataset for all clusters and large gene set databases.

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Automated marker descriptor for single-cell RNA-seq | Washington University in Saint Louis / ITMO University

students: Daria Gorbach
scientific adviser: Konstantin Zaitsev

Method of single-cell RNA-seq provides an opportunity to detect gene expression and specific cellular processes from lots of cells simultaneously, and each cell type has its own combination of expressed markers, which helps to discriminate one cell population from another. Increasing rate of RNA-seq technologies demands automated methods to obtain increasing amount of that data. Popular approach of cell types identification is based on "one versus all" method, which compares gene expression profiles for one cellular cluster with all the rest. It is a way to find statistically significant markers for each cluster, however, this method fails to identify "unique" cluster markers and quite often reports markers that are not unique for a certain cluster. Cell surface markers are of particular interest for that kind of research, as they are most frequently serve as markers of specific cell types.

Our approach was to make an automated descriptor, using pair-wise comparison of expressed markers. We used MGI database for mice cell surface proteins and "Seurat" package – R toolkit for single-cell data analysis. Thus, we compared expression levels of each cell surface marker between different cellular subtypes (T h -lymphocytes, macrophages, etc.) and obtained one or several unique markers expressed uniquely in each subtype. This method allows us to describe each cluster with a set of unique surface marker genes identifying any of that type.

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The effect of X chromosome inactivation on the expression of autosomal genes | Bioinformatic institute

students: Daria Kilina
scientific advisers: Yury Barbitov, Rostoslav Skitchenko

X chromosome inactivation (XCI) silences the transcription of genes located on one of the X chromosomes to balance expression dosage between XX females and XY males. According to a recent work by Tukiainen et al., there is no total X chromosome inactivation in humans as up to one-third of X-chromosomal genes are expressed from both the active and inactive X chromosomes in female cells. Howeer, the effects of XCI on the expression profile of autosomal genes have not yet been assessed. In this study we compared the expression of autosomal genes in cells with different active X chromosome copies.

To answer this qestion we analyzed public experimental data of single-cell RNA-sequencing of pancreatic islets from one female individual. We aligned the reads coming from each cell to a reference genome assembly using bowtie2. We then performed variant calling with samtools/bcftools in order to group the cells by active X chromosome by visual inspection of the alignments and SNP calls in IGV. We grouped the cells by alleles at variant sites in the XIST gene that is totally expressed from only one X chromosome. We then quantified gene expression levels with RSEM and used LIMMA plugin in the Phantasus browser to compare gene expression in the two groups of cells defined above.

We identified some candidate genes, expression of which depends on the active X chromosome copy; however, the difference in the expression levels of these genes between groups was not significant (P-value < 0.05, adjusted P-value > 0.05). Furthermore, we observed lack of clear separation between the two groups of cells based on principal component analysis (PCA), which may indicate confounding effect of cell types or other factors. Hence, the effect of differential genes expression from the X chromosomes on the expression profile of autosomal genes needs further investigation.

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Increasing the length of introns due to transposable elements | Vavilov Institute of General Genetics Russian RAS

students: Anastasiia Murzina
scientific adviser: Irina Poverennaya

Unlike exons - coding regions of a gene, intron sequences are known for a high degree of mutagenesis and, in accordance with this, great variability, so that even the length of an intron can differ greatly in related organisms. A significant increase in the length of introns may be due to the active accumulation in introns of a large number of transposable elements (TE) and repeats. In this project, our goal was to get depence between intron length and count of transposable elements.

The Dfam database is a collection of Repetitive DNA element sequence alignments. This database was used with RepeatMasker programm, which based on usage Hidden Markov Models, to search TE of human genome. TE and repeats take up 43 percent on the average of the length of all introns. There is a correlation between the intron length and the TE length for introns with a length of more than 300 nucleotides, however, very long introns (> 12000) correlate with the TE length better than the average length introns.

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Аnalysis of factors affecting the course of chronic myeloid leukemia | Pavlov First Saint Petersburg State Medical University

students: Nadezda Pogodina, Irina Babkina
scientific advisers: Eugene Bakin, Oksana Stanevich

Chronic myeloid leukemia (CML) is a myeloproliferative disorder characterized by unregulated granulocytic proliferation. A standard treatment includes tyrosine kinase inhibitor (TKI) and hematopoietic stem cell transplantation (HSCT). In this project, our goal was to identify the factors that have an impact on survival after HSCT. The most common method of survival analysis is a Kaplan-Meier approach. These method works on censored data, when observation ended up before event of interest occurred. We plotted overall and event-free survival curves. Cumulative survival probability was 37.9%. Then, we performed analysis of single variables (conditioning regimens, phase of CML et al.) and compared survival curves in log-rank test. We identified one statistically significant factor: cyclophosphamide therapy after HSCT (p-value = 0.03). CML therapy has been improved, so we used multivariate analysis to assess the influence of new treatment methods on the survival using correlation test. Correlation matrix showed weak association, that's why we selected the following factors with the specialist`s help: conditioning regimens, phase of CML, graft compatibility, TKI therapy, cyclophosphamide therapy after HSCT. Ordination methods (PCA and MDS) showed 3 clusters of therapy factors, distributed between 3 era: 1995-2006, 2007-2012, 2013-2018. The eras' survival curves were also statistically different (p-value = 0.009).

Slides
Identification of pathway genes triggered differential expression profile changes | Pavlov First Saint Petersburg State Medical University

students: Daria Gorbach
scientific advisers: Eugene Bakin, Oksana Stanevich

Analysis of complex cellular pathways can be an issue. However, despite dozens of possible interconnections between genes in the pathway, it only requires to know the few key genes, that invokes changes in differential expression profile. In recent work we managed to find key genes that orchestrate early changes in differential expression during the Kaposi's sarcoma-associated herpesvirus (KSHV) invasion.

We used the real clinical data from cells infected with KSHV - a table of differentially expressed genes, that was previously visualized and selected in the Phantasus software. Then, we intersected these genes with pathways from the KEGG ((Kyoto Encyclopedia of Genes and Genomes) database, to choose pathways, that contain genes of interest. Selected pathways were processed using the KEGGgraph R package. We applied so called "breadth-first search", as we search for every "descendant gene" of every
single gene in the pathway and compared the number of differentially expressed ones among them. Gene, that has the biggest amount of those genes (and the lesser number of non-differentially expressed descendants) is considered to be "the key gene", that initiate following changes in that part of the pathway.

All genes from KSHV-infected cells data were intersected with KEGG database (KEGG.db) and, as a result, 143 pathways possibly related with KSHV were obtained, and 6 perspective "key genes" were identified. We also proved its connection with KSHV pathogenesis (from literature data).

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Analysis of yeast genomes from the Peterhof genetic collection | Bioinformatics Institute

students: Anton Matiiv
scientific advisers: Yury Barbitoff, Alexander Predeus

The Peterhof genetic collection of Saccharomyces cerevisiae strains (PGC) is a large
laboratory fund, which has accumulated several thousand strains for more than half a century. Several PGC strains have been widely used in certain areas of yeast research, but their genomes have not yet been fully studied. The genetic distance between the precursor PGC and S288C is comparable to that between two geographically isolated populations. This project is a continuation of a project to assemble the yeast genome from Oxford Nanopore (ONT) data.

During this project it was supposed to identify compensatory mutations that allow cells to
survive with the disruption of the gene encoding the vital translation termination factor.
At the moment we have obtained 3 genome assemblies of Saccharomyces cerevisiae
1A-D1628 strain: (1) draft genome assembly from ONT reads, that was assembled previously with canu, (2) enhanced polished with Nanopolish genome assembly, and (3) even more enhanced with Racon and Nanopolish genome assembly. If compared with QUAST, the final (3) assemble had 205.12 mismatches per 100 kbp (against 212.37 for (1) and 207.85 for (2)) and 25.04 ndels per 100 kbp (against 343.76 for (1) and 73.09 for (2)). So, we can assume enhanced with Racon and Nanopolish genome assembly is our best genome assembly of Saccharomyces cerevisiae 1A-D1628 strain.

In order to make annotation of Saccharomyces cerevisiae 1A-D1628 strain we used
Exonerate, Maker, RGAAT and RAAT tools. But only with Exonerate it was possible to
create annotation with similar gene numbers compared with closely related Saccharomyces cerevisiae S288C strain. Also, this obtained annotation was used for SnpEff database building.

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Systematic comparison of state-of-the-art variant callers' performance | Bioinformatics Institute

students: Ruslan Abasov, Varvara Tvorogova
scientific advisers: Anton Shikov, Yury Barbitoff

Exome sequencing is the technology of sequencing all protein-coding parts of the
genome, i.e.,sequencing of all exons. Exome sequencing is widely used in medical genetics as most of the relevant variations are concentrated in the coding loci. The processing of raw exome sequencing reads generally includes read alignment, variant calling, and filtering of the identified variants (single-nucleotide polymorphisms (SNPs) and insertion-deletion variants (indels)) using various methods. The output of such pipeline represents a VCF file containing a list of variants identified in one or several samples. When analyzing the human genomes, especially when searching for variants associated with disease, the accuracy of variant calling is extremely important. Our goal was to evaluate this accuracy for different variant calling pipelines.

The main goal of this project was to compare different pipelines for exome variant
calling. We used the following tools in our analysis: GATK3, GATK4, STRELKA v. 2.9.10,
DEEPVARIANT v. 0.7.2, and FREEBAYES v. 1.2.0. For evaluation of the accuracy of small variant discovery we used the gold standard datasets from the Genome In A Bottle (GIAB) Project, as well as the recently developed Synthetic Diploid Sequence (SynDip) benchmark dataset. We compared the average quality of the variant calls across all samples using the F1 metric that is widely used to evaluate the performance of classification algorithms. For small indels, the older version of GATK - GATK3 showed the best variant call quality, unexpectedly outperforming the newer version of the tool, GATK4. For SNPs, DEEPVARIANT showed the best results. We also found that the variant call quality is highly variable among different samples even for the same variant calling tool, supposing that factors other than variant caller, such as sequencing coverage, sample preparation, and type of experiment (exome or genome sequencing), also influence the accuracy of small variant discovery.

Slides
Implied weighting as a measure of clade support: automation of the task and comparative assessment of results | Saint Petersburg State University

students: Ekaterina Sytnik
scientific advisers: Lavrentii Danilov, Fedor Konstantinov

Implied weighting (IW) is a method in parsimonial phylogenetic analysis that allows to
assign weights to characters in data according to their appearance in homoplasies and
additional parameter k. k - parameter that describes the degree of concavity of the function, which describes the weight of signs This method is usually used for morphological data for which some characters are more important than others. This is important for parsimonial analysis and assigning weights can significantly affect the resulting trees.

The most common program for IW analysis is TNT which was developed by Goloboff. It has a default k = 3 which is considered not recommended due to eliminating of homoplasies at lower k values. At the same time there is no consensus about optimal k value, usually only one value is used.

We have used the idea of applying IW with different k values as a clade support method as more stable clades should be obtained in the wide range of k values. We have constructed TNT and Python scripts allows to set minimal and maximum for k and calculate optimal k values based on logarithmic scale. Initial tree and IW are done using command-line TNT. The output of the scripts is a majority-consensus tree with bootstrap values calculated as a percentage of k values where this clade is presented. Resulting tree can be received is user- defined format (nexus, newick, phyloxml, nexml, cdao).

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Antimicrobial peptide prediction in non-model species based on transcriptome data | Institute of Biology at Irkutsk State University

students: Irina Babkina
scientific advisers: Polina Drozdova

Lake Baikal hosts a unique deep-water freshwater fauna, which includes various
representatives living in a wide range of environmental conditions, from the littoral zone to
the maximum depth. The main diet of deep-water representatives is carrion with a specific
saprotrophic microbiota. Thus, the deep-water crustaceans are assumed to have a variety of protection mechanisms against pathogens, including antimicrobial peptides (AMPs).
RNA-seq data can be used to predict the proteome, and thus they can also be used to search for AMPs. Kim et al., 2016 developed a pipeline to search for AMPs in cockroach transcripts.

However, the specifics of our data and additional interest also to the cryptic AMPS require its improvement. To search for known AMP, we performed a blastp search on the db_AMP database. In transcripts of 2 species, Ommatogammarus flavus and Eulimnogammarus verrucosus, 4 groups of proteins similar in structure to decapod crustins were found. All of them have homologous sequences within the published amphipod transcriptomes. Earlier, crustins of amphipods have never been described in detail.

For the prediction of AMPs, we used the pipeline from Kim et al., 2016 with an additional
step to search for cryptic AMP. In the Ommatogammarus flavus transcriptome, we
discovered 916 potential AMPs that need to be checked in vitro and in vivo.

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Diversity of opsins in transcriptomes of Baikal endemic amphipodes | Institute of Biology at Irkutsk State University

students: Alena Kizenko, Yana Fedorova
scientific advisers: Polina Drozdova

Amphipoda are malacostracan crustaceans generally characterized with laterally compressed bodies. Amphipod species inhabit different areas and depths of seas and freshwater bodies. Orientation of amphipods in water is regulated by opsins, G protein-coupled transmembrane receptors, which form visual pigments together with retinal chromophores and play key roles in animal photoreception. Baikal endemic amphipods vary in habitat and color, so the aim of this project was to discover which opsin genes these amphipods have and how natural selection has influenced the representation of opsin types.

We analyzed quality of transcriptomes using BUSCO v3 (Benchmarking Universal Single-
Copy Orthologs). As the quality of assemblies was rather bad, we filtered out species
transcriptomes of which possessed more than 20% missing BUSCOs. Then we applied the PIA (phylogenetically-informed annotation) pipeline to the remaining transcriptome
assemblies. We slightly modified this pipeline to make it more useful for genes' search in
transcriptomes of bad quality and added the Gblocks step. Gblocks eliminates poorly aligned positions, which can occur due to the partial CDS alignment, so that alignment becomes more suitable for phylogenetic analysis.

Finally, we discovered that Baikal amphipods possessed only long-wave sensitive opsin genes and opsin-like proteins. We suppose that Baikal amphipods have lost the expression of short-wave and ultraviolet sensitive opsins due to natural selection.

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Whole-genome Drosophila sequence analysis | EPAM Systems, Lifesciencs department

students: Anastasia Kosolapova, Iury Lebeda
scientific advisers: Gennady Zakharov

Drosophila fruit fly (D.melanogaster) is a widely known and popular model organism. Due to the small size of the Drosophila genome and its rapid reproduction, it is fairly easy to study various conditions and diseases. In this work, DNA sequences of two mutant D.melanogaster strains (X1 and ts3) with disturbances in the structure and functioning of the nervous system, and three wild- type strains without physiological pathologies were studied. Both of these mutant strains can potentially be used to study Williams syndrome in humans.

After the initial quality control of the Illumina NGS reads, they were aligned to the reference genome, and variations were found in each strain. After that, from the list of variants of mutant strains, variants of wild-type strains were removed. In the region of limk1 gene (potential origin of variations forming mutant phenotype according to previous studies), several variations were found that were identical for both mutant strains; however, after filtration these variants were eliminated. The final set of variations unique for mutant strains was divided into groups by significance for manual analysis.

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Searching for latent viruses in human whole genome sequencing data | Genotek

students: Alisa Morshneva, Nadezda Pogodina, Iury Orlov
scientific advisers: Valery Ilinsky, Alexander Rakitko

Viral ability to stay in an asymptomatic phase of infection when a virus is not replicating is
known as latency. A virus can stay latent for decades without exposing itself, although
maintaining a capability to cause acute infections. Hence, viral presence in the human
organism can remain undetected.

Human whole-genome sequencing data contain sequences of dsDNA-viruses (or integrated RNA-viruses) apart from human sequences, because all such sequences are technically indistinguishable in the host DNA. The viral sequences aren't aligned to the reference human genome and can be identified by mapping to the viral genomes. There are six viral families which we initially expected to observe as they store their genetic material in dsDNA form: Adenoviridae, Herpesviridae, Poxviridae and Polyomaviridae (linear dsDNA), Papovaviridae and Hepadnaviridae (circular dsDNA).

In this project we estimated the viral load in WGS data (blood samples) from private Genotek database and 1000 Genomes project. For this purpose we developed a pipeline for detecting viruses in human WGS data using Kraken2. Almost in all the samples Epstein-Barr virus (EBV) was found. Mastadenoviruses were detected only in 23% of the samples. In order to determine an associations between viral load level of EBV/viral presence of Mastadenoviruses and SNPs in human genome we performed GWAS using genuine Genotek pipeline on 5 european populations from 1000 Genomes project (CEU, FIN, GBR, IBS, TSI). GWAS revealed several significant SNPs possibly connected with the viral load rate. However, their functions should be explored.

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Detection of pathogenic INDELs and SNPs in whole-exome sequencing data of patients with
different types of idiopathic cardiomyopathy
| Almazov National Medical Research Centre

students: Daria Kilina
scientific advisers: Artem Kiselev

Idiopathic cardiomyopathy is a primary cardiovascular disease with high heterogeneity
caused by functional lesion in cardiomyocytes in consequence of genetic abnormalities. In
this study, we undertook a whole exome sequencing (WES) approach to identify novel
candidate single nucleotide polymorphisms (SNPs) and insertions/deletions (INDELs)
associated with different types of idiopathic cardiomyopathies.

The cohort consisted of 10 patients with idiopathic cardiomyopathy. This samples were
processed with Variant Calling pipeline (GATK) implemented on Snakemake and annotated by annovar, snpEff. The total number of SNPs - 203 827, insertions - 14 352, deletions - 19 891. Among discovered SNP 48.07% variants were missense, 51,38% variants were silent and 0,55% were nonsens. As a result of comparing the allele frequencies of observed variants against all ExAC population and taking into account the tool prediction (SIFT, Polyphen2, LRT, MutationTaster, MutationAssessor, FATHMM, Provean, CADD, MetaSVM) 6 previously unknown SNPs with damage effect were detected. New INDELs variants haven't been identified.

Mutation in SLC2A8 gene can lead to increased reliance on glucose utilization contribute to the development of cardiac dysfunction, but we cannot state it with certainty on this stage of the project. Hence, the effect of discovered mutations on the pathogenesis of idiopathic cardiomyopathy needs further investigation.

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Detection of CNVs in patients with different types of idiopathic cardiomyopathies | Federal Almazov Medical Research Center

students: Olga Romanova
scientific advisers: Artem Kiselev

Array comparative genomic hybridization (aCGH) is considered the gold standard for
copy number variation (CNV) detection. However, next-generation sequencing (NGS) is
developing rapidly. To date there are a lot of NGS laboratories which are using analysis of
whole-exome sequencing in the medical diagnostic of inherited diseases. Despite of NGS
technology is widely disseminated, it is generally not used for CNV detection. We believe that using NGS to identify CNVs and SNVs could be of benefit to laboratories saving time and reducing costs while creating a more comprehensive picture of genomic variation with a single assay.

An aim of this study was to detect of CNVs in whole-exome sequencing data of
patients with different types of idiopathic cardiomyopathies. To achieve our goal, we realized two pipelines CNVkit (https://github.com/etal/cnvkit) and ClinCNV
(https://github.com/imgag/ClinCNV) using snakemake, analyzed a cohort of 10 patients'
whole-exome sequencing data using developed scripts and carried out research clinically
relevant structural variants in patients with different types of idiopathic cardiomyopathies.
With regard to findings of the study there was detect a chromosomal 15q partial
deletion (q11.2-q13.1) in one of the patients. This structural variation was verified by aCGH.

According the literature, the loss of this region associated with Prader-Willi syndrome (PWS).

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SPAdes support for third-party assembly graphs | Center for Algorithmic Biotechnology

students: Natalia Zenkova
scientific advisers: Anton Korobeynikov, Andrey Prjibelski

SPAdes – St. Petersburg genome assembler – is an assembly toolkit containing various
assembly pipelines. SPAdes outputs contigs and genome assembly graph in FASTG and GFA formats, but do not have the ability to accept such graphs as input. FASTG is a format for faithfully for representation of genome assemblies in the face of allelic polymorphism and assembly assembling uncertainty. The Graphical Fragment Assembly (GFA) is a tab- delimited text format for describing a set of sequences and their overlap. The goal of this research project was implementation of support for third-party assembly graphs, in particular, graph gfa format. The implementation of this functionality significantly expands using SPAdes. It allows using repeat resolution and scaffolding based on graphs and built by other genome assemblies. For this implementation the new stage load_graph replacing stages construction and simplification was constructed. For downloading graph class LoadGraph was created. At the moment, SPAdes accepts GFA graph from load_graph stage with Load function. Coverage for edges are read from GFA file.

There is another problem: SPAdes accepts de Bruijn graph as input and do not have the
ability to input another type of sequence graph with overlap equal to zero. The simpler
algorithm was proposed for solving this problem. The goal is transforming arbitrary graph to deBruijn graph. This algorithm consists of three stages: iteration through vertices,
continuation outgoing edges and complementary edges and repeat until all vertices are
processed. But this method is not universal. It is necessary to modificate this algorithm for
some cases: e.g. for situations where there are equal edges, edges shorter than k, where k is k- mer size, in input graph or there is an vertex containing different incoming and different outgoing edges.

Slides
Bayesian optimization for demographic history inference | ITMO University / St. Petersburg State University

students: Ilya Sheshukov
scientific advisers: Ekaterina Noskova, Vyacheslav Borovitskiy

Demographic histories are studied in population genetics to infer the way populations migrate, split and change its size.. One of the most used tools in this area is moments.
The project goal was to replace a BFGS (Broyden Fletcher Goldfarb Shanno) optimization
algorithm used in the moments tool with the Gaussian process based global Bayesian
optimization and to study the effects. Bayesian optimization is a family of global optimization algorithms which can be more appropriate for a given task.

As a result, we successfully integrated optimization routine from the library GPyOpt into
moments. Then we compared the results: our non-exhaustive tests showed that our solution was converging faster than the moments library. Later more exhaustive testing needs to be done.

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Adaptation of fish to the depth | Lomonosov Moscow State University

students: Anna Namyatova, Elena Polyakova
scientific advisers: Nadezhda Potapova

Previously it was shown that most species of deep water fishes possess a rod-only retina with a pigment that is usually shortwave (Hunt et al. 2001). Therefore, it can be suggested that there might be similar changes in the rhodopsin protein in different species, leading to the same adaptation.

To test this hypothesis we downloaded the rhodopsin sequences from Genbank belonging to 34 deep water fish species from seven orders with the recoded depth of living exceeding 3000 m. We also downloaded the rhodopsin sequences for 28 shallow water species. The aminoacid sequences were aligned in Geneious software. Based on this alignment, we calculated the frequencies of the aminoacid changes using the Python script. For comparison between the deep water and shallow water fishes we calculated the differences between the squared frequences of the each aminoacid change in deep water fish and shallow water fish.

We chose the changes based on the following criteria: (1) the difference of the squared
frequences should be > 0.3; (2) there should be more changes in the deep water fishes than in the shallow water fishes; (3) the identical change should occur in >2 orders. Overall, six changes fitted our criteria. We also showed that all those changes were in the domain and that the replacing aminoacids were very similar to the replaced aminoacids in two positions ( <30 based on the Grantham's score).

The further analysis requires checking the active sites of the protein to draw conclusion on
the importance of the found changes for the protein function. Running the analysis for the
larger dataset will provide more robust results.

Slides
Interactive networks of phenotypes / genes / metabolic pathways | Genotek

students: Lonishin Lubov
scientific advisers: Rakitko Alexander

For consultations on the results of a genetic test, it is convenient to have before your eyes information on a phenotype (for example, a disease) and its relationships, presented in a structured form. In this project, it is proposed to implement an R-Shiny application that will display in the form of interactive networks:
- the relationship between phenotypes (which is a risk factor for which);
- gene networks (with the patient variants marked on them);
- metabolic pathways.

Slides
Effect of smoking on human leukocyte epigenome | Institute of Cytology RAS / A.N. Belozersky Research Institute Of Physico-Chemical Biology

students: Polina Pavlova, Maria Firuleva
scientific advisers: Oleg Sergeyev, Yury Kornienko

Environmental factors, including chemicals, can cause epigenetic changes that can be traced to subsequent generations. The most studied epigenetic changes are DNA methylation, small non-coding RNA, and histone modification. Smoking remains one of the most adverse voluntary health risks. Reduced representation bisulfite sequencing (RRBS) data can be used to study the pattern of methylation changes upon exposure to smoking.

Our project is a part of the Russian Children's Study, a prospective cohort of 516 boys who were enrolled at 8–9 years of age and provided semen and blood samples at 18–19 years of age (Sergeyev et al, 2017). We analysed smoking influence on the DNA methylation level of peripheral blood leukocytes at the age of 18. To search for differentially methylated CpG islands and regions (DMR), we used two different approaches. To implement the first approach, we used data from the CpG islands presented in all samples of peripheral blood. After exclusion regions that did not meet the inclusion criteria, we used the A-clustering algorithm (Sofer et al, 2013) to combine the regions into clusters and generalized estimating equation model to search for significant DMRs. With this approach we identified 217 A-clusters, from them 77 were significant (p-value &lt; 0.05). Because for A- clustering implementation we needed to restrict our data, a lot of important information could have been lost.

DMRcate - R package for search of differentially methylated regions (DMRs) associated with exposure to a factor (Peters at al, 2015). In our project, we used smoking past half year in binary classification (smoke or not) to find DMRs associated with exposure. 145 significant CpGs and 34 significant DMRs (p-value &lt; 0.05) were found in our data. From them 19 DMRs overlap with at least one promoter (reference - GRCh 38). We found 23 genes associated with significant DMRs. These genes are associated with antisense RNAs, lincRNAs, miRNA, pseudogenes, zinc fingers, transcriptional factor, spliceosome, cell adhesion and migration, kinase, metalloprotease, electron transport chain and amino-acid transporter.

Finally, we found DMRs using two different statistical strategies for analysis of DNA RRBS
data. Further research plans include the analysis of changes in the expression of various
groups of small RNAs, as well as a comparative analysis of leukocyte and semen RRBS data.

Slides
The influence of molecular dynamics parameters on protein motion
characteristic timescale
| St. Petersburg State University / Purdue University

students: Olga Lebedenko, Stanislav Legkovoy
scientific advisers: Nikolai Skrynnikov

Molecular dynamics (MD) modeling of biomolecules is one of the most important and promising tools of structural biology. As a rule, in MD simulations of biomolecules use the so-called NPT ensemble. However, the use of NPT with a standard set of parameters for barostat and thermostat may lead to significant changes in the characteristic time scale of the simulated motions.

The main objective of this project was to find optimal parameters for correct representation of motional timescales in two structurally dissimilar proteins: globular protein ubiquitin (ubq) and intrinsically disordered N-terminal fragment of histone H4 (h4). In this work, we recorded and processed a number of MD trajectories using different water models (spce, tip3p, tip4p-d, tip4p- ew) and ensembles (NVE, NVT, NPT γ=0.01, NPT γ=2) under Amber ff14SB force field. Based on these trajectories, we calculated the characteristic times of rotational motion for globular ubq protein. Furthermore, the characteristic times of translational diffusion for ubq and h4 have also been calculated.

As a next step, we compared all MD-derived correlation times with the corresponding
experimental values. It was found that certain combinations of water models and statistical
ensembles correctly reproduce the rotational diffusion process (overall tumbling): spce / NVE, tip4p-ew / NVE, tip4p-ew / NPT (γ = 0.01), tip4p-d / NVE. However, translational diffusion requires further investigation since none of the attempted procedures produced the correct results for both ubq and h4.

We would like to thank Prof. D.A. Case for drawing our attention to this problem.

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Determination of the most probable genotype and ethnicity of an individual based on the genotype of his descendants | University of La Verne

students: Isaev Vasilii
scientific advisers: Tatrinova Tatiana

In forensic practice, there is such a task: there is a rape victim, there is a child born as a result of a crime. The offender (father) is unknown. How to most accurately get a description of it based on the genotypes of the mother and child? What methods (genome-wide sequencing or chip analysis) will be most effective? Is it possible to reliably determine the ethnicity of the father? We will look for answers to these questions this semester.

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Local sequence alignment using intra-processor parallelism | University of Warwick

students: Dmitry Orekhov
scientific advisers: Alexander Tiskin

Local alignment of DNA sequences is a fundamental problem of bioinformatics. Standard
solutions include fast heuristic methods such as BLAST, as well as the more time-consuming exact methods. An efficient exact local alignment technique, based on a "sliding window" approach, was developed by a University of Warwick team, resulting in a number of biologically significant results. The efficiency of that implementation was achieved, in particular, by utilising low-level intra-processor parallelism. In recent years, commodity processor architecture has been developing rapidly, culminating with Intel's AVX-512, an instruction set taking intra-processor parallelism to a new level of efficiency and sophistication, while also being surprisingly well-suited for speeding up the "seaweed
combing'' sequence alignment technique developed by the second author.

We developed a prototype software tool that is, to our knowledge, the first sequence
alignment software taking advantage of AVX-512 parallelism. Our tool allows one to produce semi-local alignments between short DNA fragments and long DNA strings, using seaweed combing and intra-processor parallelism to achieve competitive performance. In future, we plan to extend our implementation to a very fast exact local sequence aligner with "sliding window" functionality.

Slides
Association Rule Mining using fishbone diagrams | JetBrains Research

students: Nina Lukashina, Daria Likholetova
scientific advisers: Petr Tsurinov, Oleg Shpynov

Exploiting associations is central in human reasoning and decision making. There is a lot of rule extraction techniques from observational data. Association Rule Mining (ARM) is one of the most popular methods. Fishbone ARM (FARM) is a new data mining algorithm for constructing hierarchical associations, which can be visualized as Ishikawa diagrams. FARM was developed by JetBrains Research, and our tasks were to create a web service and validate the method on real biological datasets.

In this study we improved method usability and created the web application which allows to go from raw data to visualization in web browser. Several other data-mining algorithms were implemented: FP-growth ARM and Decision Tree. Comparison of FARM with existing methods showed its superior clarity in reporting results.

We applied FARM to data from the study "A Validated Regulatory Network for Th17 Cell
Specification" (Ciofani et al., 2012). Authors used genome-wide TF occupancy, expression
profiling of TF mutants, and expression time series to delineate the Th17 global
transcriptional regulatory network, identifying multiple new Th17 regulators. FARM was able to reconstruct main complexes of TFs acting in the Th0-Th17 differentiation process.
After FARM validation on genome data we focused on biochemistry assays of blood and
urine datasets to construct fishbone diagrams for old and young patients, and found
associations of creatinine clearance and TNF-alpha receptor I, previously reported to be
connected with age (Ogna et al., 2015, Schaap et al., 2009).

Slides
Noisy peak calling | JetBrains Research

students: Daria Chaplygina
scientific advisers: Oleg Shpynov

Chromatin immunoprecipitation followed by high-throughput sequencing (ChIP-seq) is a
method used to analyze protein interactions with DNA. The goal of peak calling algorithm is to identify enriched areas (peaks) in a genome.

In the paper "Impact of sequencing depth in ChIP-seq experiments" (Jung et al., 2014)
authors evaluated the impact of sequencing depth on peaks identification. However, signal-to-noise characteristics and its influence on peak calling algorithms were not covered. In this work we tried to estimate the impact of noise level in ChIP-seq data on enriched regions identification for core histone marks (H3K27ac, H3K27me3, H3K36me3, H3K4me1 and H3K4me3). We focused on MACS2 (Zhang, et al., 2008), SICER (Xu et al., 2009) and SPAN (novel semi-supervised peak calling algorithm by JetBrains Research) algorithms. The noise was introduced by mixing ChIP-seq and control reads with different proportions of control ranging from 0% to 90%. SICER and SPAN were used with default parameters and MACS2 with parameter --broad. False Discovery Rate (FDR) was set to 0.05 and 1E-6 to evaluate its influence on peak calling capabilities with noisy data.

The analysis of peaks dynamics demonstrated that both number of peaks and average length are decreasing with the increase of noise level. Then we compared algorithms by its stability and identified sets of peaks. We found that SPAN with FDR 0.05 is the most stable of three algorithms and higher noise level leads to lower peaks sets similarity. Investigation of FDR influence showed that more strong FDR values result in decreasing in both peak callers stability and peaks sets similarity.

Slides
Denoising of ULI-NChIP-seq data with neural networks | JetBrains Research

students: Daria Balashova
scientific advisers: Oleg Shpynov

Chromatin immunoprecipitation followed by sequencing of the next generation
(ChIP-Seq) is a powerful method for identifying the entire genome&#39;s DNA binding
sites for transcription factors and other proteins. The limitations of ChIP-seq include
a large number of cells needed to create high-quality data sets. The ultra-low-input
micrococcal nuclease-based native ChIP (ULI-NChIP) protocol, that was presented
in the paper "An ultra-low-input native ChIP-seq protocol for genome-wide profiling of
rare cell populations" (Brind&#39;Amour J et al., 2015), requires significantly less material
and usually provides a reliable peak calling, but is much more variable than the
traditional ChIP-seq approach.

In the paper "Denoising genome-wide histone ChIP-seq with convolutional neural
networks" (Pang Wei Koh et al., 2017) authors introduce a convolutional denoising
algorithm, Coda, that uses convolutional neural networks to learn a mapping from
suboptimal to high-quality histone ChIP-seq data. We analyzed the ULI-NChIP-seq
data quality of histone modifications H3K27ac, H3K27me3, H3K36me3, H3K4me1
and H3K4me3 and focused on the signal-to-noise ratio (SNR) metric. We present
DCNN algorithm – denoising convolutional neural network – the purpose of which is
to improve the quality of the data with respect to the SNR. The essence of the
method lies in the matching of high and low quality data of some histone
modification, as well as, optionally, using data of other histone modifications to
improve accuracy. This approach allows to transfer information from low-input noisy
processes in a flexible model that can be used for noise reduction of new ULI-
NChIP-seq data.

Slides
Improving peak calling in SPAN | JetBrains Research

students: Elena Kartysheva
scientific advisers: Alexey Dievskii

ChIP-seq (chromatin immunoprecipitation sequencing) is one of the main methods to analyse DNA-protein interactions. It can be really helpful but it produces a lot of noisy data so the output has to be carefully preprocessed before being used. SPAN (Semi-supervised Peak ANalyzer) is a multipurpose peak caller capable processing both conventional and ULI- Chip-seq tracks.

The main goal of this study was to improve the peak caller model by adding new covariates to HMM (hidden markov model) using GLM (generalised linear model). We used ZINBA (Zero-Inflated Negative Binomial Algorithm) as a reference.

In this semester several classes were implemented for bioinf-commons such as weighted
regression, emission regression scheme, poisson regression scheme and zero-poisson mixture to extend the library with methods necessary for future integration of new covariates. One of the aforementioned classes (namely weighted regression) was proposed as a pull request to Apache Commons Statistics developer branch.

In future we plan to add zero-poisson mixture to SPAN model, test it on real data and replace poisson regression with negative binomial if necessary.

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Towards detection of differential RNA editing events in transcriptomics datasets. | St.Petersburg State University

students: Andrey Matveenko,
scientific advisers: Anastasia Samsonova, Alexander Kanapin

Single-nucleotide modifications of RNA, or RNA editing, is an important regulatory
mechanism in the cell. However, understanding of its regulation is far from complete,
as transcriptome-wide quantitation of the RNA editing is complicated and requires
developement of new computational approaches. Most tools for RNA editing analysis
are limited to the search of potential editing sites and do not support the analysis of
differential editing (DEd). On the other hand, great number of approaches exists for
analysis of differential methylation (DM), specifically, bisulfite sequencing, which is
similar in data modality to the RNA editing. In this project we aimed to evaluate
applicability of existing tools and statistical approaches for analyses of bisulfite
sequencing data, for discovery of DEd events.

We attempted to identify DEd sites and genes in the RNASeq data of BT20 cell line.
The samples were prepared either under hypoxia or in normoxia, three replicates per
condition. Previously, in a work by Irina Shchukina, a tool for discovery of A to I
RNA editing events in RNASeq data was developed. The output of this tool listing
editing sites determined in the cell line was used as the data for the subsequent
analysis. edgeR pipeline for analysis of DM was modified here to apply for the DEd
analysis both at single-nucleotide and at gene level. As the result we obtained lists of
DEd sites and genes in the sample, and found that RNA editing of approximately 100
genes is enhanced under hypoxia. GO-enrichement analysis of the gene list revealed
that RNA editing is enhanced during hypoxia in genes acting in ribosome biogenesis,
mitochondrial translation, and transcriptional regulation associated with hypoxia.
Thus, edgeR DM pipeline can be used for differential RNA editing analysis.

Slides
Обнаружение и разделение сигналов вариации в данных секвенирования РНК одиночных клеток | Университет ИТМО

студент: Фирулева Мария
руководитель: Зайцев Константин

Разработка методов разделения вариации в данных scRNA-seq.

Слайды
Association rule mining using fishbone diagrams | JetBrains research

студенты: Лихолетова Дарья, Лукашина Нина
руководитель: Цуринов Пётр

Продолжение проекта "Association rule mining using fishbone diagrams" с весеннего семестра
Поиск маркеров потенциальных осложнений при беременности по данным секвенирования внеклеточной ДНК из плазмы крови матери | НИИ АГиР им.Д.О.Оттa

студент: Моршнева Алиса
руководители: Глотов Андрей Сергеевич, Козюлина Полина Юрьевна

На данным момент мы имеем базу (около 400 образцов) секвенированной внеклеточной ДНК из плазмы крови беременных женщин с высоким риском развития патологий. На основе этих данных был разработан НИПТ-тест для определения анеуплоидий плода, который теперь проводится у нас в клинике. Однако потенциально данные полногеномного секвенирования могут быть использованы для диагностики не только патологий плода, но и материнских заболеваний и осложнений. К примеру, известно, что по данным секвенирования внеклеточной ДНК (cfDNA) из плазмы крови разработаны методы диагностики онкологических заболеваний, а также есть возможность определения вирусной нагрузки, в том числе ВИЧ. Мы хотим провести первичное исследование наших данных на возможность применения в диагностике материнских патологий с дальнейшим потенциальным применением в клинике.

Слайды
Поиск ключевых генов, инициирующих смену профиля экспрессии в клетке | ПСПбГМУ им. акад. И.П. Павлова

студент: Горбач Дарья
руководитель: Станевич Оксана Владимировна

В настоящее время реализована предварительная версия алгоритма на графах, касающегося поиска ключевых генов, инициирующих смену профиля экспрессии генов в клетке (на датасете - культура эндотелиальных клеток лимфатических сосудов, зараженных вирусом саркомы Капоши). В ходе тестирования текущей версии выяснились как технические особенности, требующие доработки алгоритма (ускорение, оптимизация кода), так и идейные - необходимо опробовать новые стратегии поиска ключевых генов, инициирующих смену экспрессии, а также опробовать алгоритм на разных датасетах.

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Опсины амфипод: уникальны ли байкальские эндемики? | НИИ биологии Иркутского государственного университета

студент: Кизенко Алена
руководитель: Дроздова Полина

Зрение -- это важно, в том числе в воде. В озере Байкал обитает 350 видов амфипод, они очень ярко окрашены (в том числе есть внутривидовое разнообразие) и обитают на всех глубинах. Тут надо отметить, что свет с разной длиной волны с разной эффективностью проникает на разные глубины, и для байкальских коттоидных рыб (кстати, хищников, которые питаются в том числе амфиподами) известен сдвиг максимальной чувствительности опсинов в синюю область с увеличением глубины обитания.

Цель: изучить разнообразие генов, кодирующих белки зрительной системы у байкальских амфипод, и поискать связь с их филогенией, глубиной обитания, яркостью окраски или другими особенностями вида.

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Improving Span | JetBrains Research

студент: Картышева Елена
руководитель: Диевский Алексей

Продолжение весеннего проекта "Improving Span".

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Определение корректных параметров МД моделирования для исследования белковой динамики | СПбГУ / Purdue University

студент: Лебеденко Ольга
руководитель: Николай Скрынников

Определение корректных параметров МД моделирования для исследования белковой динамики (в сотрудничестве с проф. Дэвидом Кейсом, создателем силового поля Амбер)

Моделирование биомолекул методом Молекулярной Динамики (МД) является одним из самых важных и перспективных инструментов структурной биологии. Как правило, в такого рода исследованиях используется так называемый ансамбль NPT. Однако использование NPT со стандартным набором параметров баростата/термостата ведёт к существенному замедлению динамики. Мы выявили этот эффект путём сопоставления экспериментальных данных, полученных методом спектроскопии ЯМР, с предсказаниями, полученными из траекторий МД. В частности, нам удалось показать, что стандартный метод моделирования ведёт к существенной (более 2 раз) переоценке характерного времени вращения глобулярного белка в растворе. В настоящее время мы ставим перед собой следующие цели.
(1) Нам предстоит выяснить насколько существенно этот эффект проявляется по отношению к движениям боковых цепей белка.
(2) Нам также предстоит установить в какой мере данный эффект сказывается на динамике нативно разупорядоченных белков.
(3) Помимо этого нас интересует его влияние на трансляционное движение белка - в особенности, в приложении к разупорядоченным белкам.
(4) Мы намерены предложить альтернативные методы моделирования, позволяющие с высокой точностью воспроизводить временной масштаб различных форм белковой динамики (например, применение ансамбля NPT с пониженным коэффициентом трения, применение ансамбля NVE).
Для записи траекторий МД наша лаборатория оснащена компьютерами на графических процессорах последнего поколения. Работа над проектом ведётся в сотрудничестве с проф. Дэвидом Кейсом (Rutgers University), создателем и ведущим разработчиком одного из двух самых совершенных силовых полей (Amber).

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Байесовская оптимизация для вывода демографических историй | Университет ИТМО /
ПОМИ РАН

студент: Шешуков Илья
руководитель: Носкова Екатерина

Демографическая история популяций это последовательность таких событий как миграция, разделение/слияние популяций, изменение их численностей. Современные методы позволяют строить правдоподобные гипотезы о демографической истории популяций по набору геномов, взятых у их "современных" представителей. Одним из ключевых этапов автоматизированных методов вывода демографической истории является оптимизация некоторой сложно-вычислимой функции без доступа к ее градиенту.

Недавно вышедший тул GADMA (https://github.com/ctlab/GADMA) решает эту задачу с помощью генетических алгоритмов. В проекте предлагается реализовать возможность использования методов Байесовской оптимизации для тула GADMA, сравнить два подхода.

Отметим, что байесовская оптимизация - не просто очередной алгоритм оптимизации, который можно за пять минут изучить в википедии, это весьма обширная и современная тема с множеством неожиданных возможностей, например оптимизации функции, используя приближения разной степени точности к ней, распараллеливание оптимизации и т.д. (вместо википедии см., например, https://arxiv.org/abs/1807.02811).

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Научные проекты 2017/2018
Осень 2017
Весна 2018
Phylogenetic networks comparison | ITMO University

students: Anton Eliseev, Natalia Klimenko, Elena Pazhenkova
scientific adviser: Nikita Alekseev

Phylogenetic networks are used to visualize evolutionary relationships that reflect any reticulations (such as hybridization). The amount of reticulation edges is a widely used criterion of networks, however, this measure is often identical in different topologies. We propose to use the number of possible convex colorings as metrics to distinguish networks with equal number of hybridizations. The number of convex colorings shows how many homoplasy-free characters are possible within this phylogeny.

Six species of Heliconius butterflies was chosen as model group to test our algorithm. A peculiar trait of genus Heliconius is the prevalence of interspecific hybridization, which reflects on phylogenetic networks as reticulation events. As suggested earlier, H. heurippa and H. elevatus have resulted from hybrid speciation [1, 2]. We analyze 20 nuclear genes, obtain NJ trees for each gene, compare these trees using pairwise Branch Score Distances, concatenate genes providing the most similar trees (distances up to 0.015), calculate hybridization networks and estimate numbers of convex colorings for each network. The network with the largest count of convex colorings is congruent with the hypothesis of hybrid origin of heurippa and elevatus species.

Another part of the study concerned the phylogeny of potatoes. 420 potato plants classified earlier as 29 species (7 cultivated and 22 wild) were analyzed by 15 plastid SSR-markers. As genomes were plastid, no hybridization was observed. We concentrated on building the most accurate phylogenetic tree for this data. Dendrograms were based on the Manhattan distance matrix. Cultivated and wild species of potato are clearly distinguishable. The idea of dividing Solanum tuberosum into Andigenum group and Chilotanum groups (according to [3]) is correct. Results of molecular analysis don't correspond to classification based on morphological features.

References:
1.Kronforst M.R., Papa R. The Functional Basis of Wing Patterning in Heliconius Butterflies: The Molecules Behind Mimicry. GENETICS. 2015. 200(1): 1-19
2.Salazar C., Baxter S.W., Pardo-Diaz C., Wu G., Surridge A., Linares M., Bermingham E., Jiggins C.D. Genetic Evidence for Hybrid Trait Speciation in Heliconius Butterflies. PLoS Genet. 2010. 6(4): e1000930.
3.Spooner D.M., Ghislain M., Simon R., Jansky S.H., Gavrilenko T. Systematics, Diversity, Genetics, and Evolution of Wild and Cultivated Potatoes. Bot. Rev. 2014. 80: 283–383

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Optimization of spectral network parameters | EPAM Lifescience

students: Evgenia Fedotova , Rostislav Skitchenko , Ksenia Cherenkova
scientific adviser: Gennadiy Zacharov
A pipeline for exome and target-sequencing analyses was developed. It's results could be used by physicians for diagnosis refinement. Such problems as pipeline deployment, it's utilities versions and dependencies control was solved by using Docker software. Pipeline quality control was obtained for NA12848 GIAB sample: Precision 0.95 and Sensitivity 0.78.

We've analyzed sequence results of cardyo-panel for families, whose members had diagnosis cardiomyopathy. Dependencies between variations and clinical diagnosis cardiomyopathy was found.

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Construction of RNA fragment database | University of North Carolina at Chapel Hill

student: Alexandr Ilin
scientific advisers: J. Wang, N. Dokholyan
RNA plays significant role in regulation of gene expression at transcriptional and translational levels. This is achieved because of appropriate spatial structure of RNA molecule (i.e. motif), which is obtained after folding. Ability to predict 3-dimensional structure given sequence of RNA oligonucleotide is very important due to possibility to make use of this information in construction molecules with predefined structure – thus with known properties and targets to interact. Therefore, it supports design of new RNAs, which can be used as medications against wide spectrum of diseases caused by consequences of problems with gene product abundance.

In this work we developed RNA secondary structure decomposition algorithm to decompose an integrated RNA into many motifs. According to the RNA secondary structure decomposition algorithm, an RNA 3D motifs database was built by decomposing all the RNA 3D structures downloaded from PDB. We devised an algorithm to analyze and compare the base interactions networks between different RNA 3D motifs. We classified and clustered all the RNA 3D motifs in the database by using the network comparison algorithm. We utilized the supervised machine learning method to learn the relationship between sequences and base interactions networks of clustered RNA 3D motifs.

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Assembly of mammalian genomes using GemCode data | Center for Algorithmic Biotechnology, St. Petersburg State University

student: Angira Kekteeva
scientific advisers: Ivan Tolstoganov, Anton Bankevich
GemCode technology that was developed by 10X Genomics Company is actively used for assembly of mammalian genomes. CloudSPAdes is a genome assembly algorithm which was designed for metagenome assembly. However, algorithms in this tool, that were developed for resolving repetitions in the assembly graph, can be successfully used for assembly of mammalian genomes.

In this work we've examined exisiting metagenome assembly algorithms and analysed the disadvatages of using them for large genomes. Our analysis has shown that the average number of close edges in a human genome graph is more, than in metagenomes assembly graph, so it requires additional methods for sequencing long edges in the genomes of mammals.

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Searching for molecular markers of chromosome bands | Bioinformatics Institute

student: Alexandra Klimina
scientific advisers: Yury Barbitoff

Giemsa staining produces specific bands on metaphase chromosomes that have coloring of different intensity (G-bands). There are known correlations between the intensity of coloring and the degree of chromatin condensation, GC-content, and replication time. However, little is known about molecular markers of such banding pattern.

Main purpose of this project was to develop a tool for analysis of genome-wide correlation between different genomic features. We implemented the tool in Java with possibility to work on Spark-cluster for distributed computitions.

We chose previously described Projection test and Jaccard test to analyze the dependence between the reference (e.g., chromosome bands) and query feature of interest. We estimated the significance of correlation by sampling 1000 sets of randomly distributed intervals of the same length as the query feature followed by Kolmogorov-Smirnov normality test and one-sample t-test to obtain the p-value of association.

We tested our tool by analyzing correlation between chromosome banding pattern and such features as CpG-islands, microsatellite repeats and DNAse hypersensitivity regions. Expectedly, we showed that G-positive bands are positively correlated with microsattelite repeats, and negatively - with CpG-islands and open chromatin, DNAse hypersensitive regions. Thus, our tool can be used to further analyze genome-wide correlations between banding pattern and diverse molecular features.

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Association of methylation level CpG-islands and IQ-level | University of Houston

student: Daria Krytskaya
scientific adviser: Olga Naumova

Methylation is an epigenomics modification of DNA. It change the activity of a DNA segment without changing the sequence. The most methylated region is region riched guanine and cytosine called CpG-islands.

In this work, we evaluate the methylation level of all known 26640 CpG-islands as average value of this region. Than we made a correlation test with using the Benjamini-Hochberg procedure for decreases the false discovery rate.

Analysis of biological role of this region was make with UCSC Genome Browser on Human Feb. 2009 (GRCh37/hg19) Assembly and GeneCards.
Among our results are predicted transcription and translation region and known protein. For example, on 1 chromosome the most significant region is (38059428, 38063740) contained: prediction region are ENST00000373062, ENST00000463351, ENST00000488496 and gene of known proteins GLN2 – Homo sapiens guanine nucleotide binding protein-like 2 (nucleolar). For region (54951893, 54957287) of 1 chromosome are not predictions. For 2 chromosome the most significant region is (65213598, 65219212) contained gene of known proteins SLC1A4 Gene – Solute Carrier Family 1 Member 4. It is a transporter of alanine, serine, cysteine, threonine. Predicts a transport of a glucose by this protein. Disorders associated with this protein are spastic tetraplegia, thin corpus callosum, progressive microcephaly, microcephaly.

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Genome structure of Mycobacterium tuberculosis strains in different world regions |
Theodosius Dobzhansky Center for Genome Bioinformatics, St. Petersburg State University

students: Vladimir Klimov, Vladimir Molchanov
scientific adviser: Ekaterina Chernyaeva

Due to the high epidemiological rate of Mycobacterium tuberculosis and its constantly updated genomic data the problem of genome data analysis and systematization becomes extremely significant. For this reason our project was devoted to extend Genome-based Mycobacterium tuberculosis Variation (GMTV) Database which was developed by the researchers of Theodosius Dobzhansky Center for Genome Bioinformatics (Chernayeva et al., 2014).

In this study we performed an analysis of 999 M. tuberculosis strains which was isolated from patients in Malawi Republic. To achieve this results we designed a pipeline aimed at single nucleotide polymorphisms (SNPs) and insertions/deletions (InDels) identification from M. tuberculosis whole genome sequencing data.

This pipeline based on BWA-mem and GATK programs which are widely used in such kind of investigations. Considering big amount of NGS data we suggested simple and rapid method to visualize or estimate quality control results performed by FastQC program using python3 regular expression and plotting in R. All variant calls (.vcf files) was uploaded on database, in future this data could be used for clade-specific annotation, which gives a possibility to identify strains without NGS methods.

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Comparative analysis of natural selection effects across human populations |
Bioinformatics Institute

student: Julia Kornienko
scientific adviser: Yury Barbitoff

In this project we aimed to estimate the natural selection effects across human populations based on the Genome Aggregation Database (gnomAD) dataset which contains information about sequence variants in 123136 human exomes and 15,496 genomes. To this end we calculated the amount of protein truncating variants (PTV) both (i) per individual genes (based on GENCODE v.19); and (ii) per gene sets (hallmarks and canonical pathways obtained from the MSigDB Collections) for six different populations (European, South Asian, Latino American, East Asian, African and Finnish).

We estimated the selective coefficients of heterozygous PTVs for different human populations from the constructed dataset in the same way as it was done by Cassa et al. (2017) and found that distribution of selective coefficients both per individual genes and gene sets is dependent on the population size. Taking this into account, we evaluated the difference in distribution of PTV allele counts among the populations and found that for 2040 of 12367 analyzed genes and for 746 of 1379 of analyzed gene sets selective effects were significantly population-dependent. Thus it is possible to conclude that selective effects for some genes do vary across the populations.

Interestingly, we discovered significant enrichment of PTV alleles in the immune system-related pathways (IL-10, IL-13 and IFNG signaling) in the individuals of South Asian ancestry (SAS), with more than half of all PTVs discovered in the corresponding genes belonging to the SAS population. These results are concordant with some previous findings and emphasize the natural heterogeneity of selective effects.

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De novo cdr3 annotation in VDJ rna sequences | Center for Algorithmic Biotechnology, St. Petersburg State University

student: Kristina Krivonosova
scientific advisers: Andrey Slabodkin, Maria Chernigovskaya
The project relates to the construction and analysis of the repertoire of antibodies. In order to build a repertoire, we look for mutations in antibodies with the help of a germline by aligning the variable part of the immunoglobulin gene with a special base of V-, D-, and J-genes (germline). With this alignment, we can annotate the sequence: we mark the boundaries of the V-gene and the J-gene, as well as the boundaries of the three regions that determine the specificity of the antibody to the antigen (CDRs). In practice the third region (CDR3) is the most variable part of the immunoglobulin gene so its borders are of the greatest interest. Unfortunately, on some data (for instance, in case of lymphoma) the level of mutations goes off the scale and we can not build an alignment on the germline for that data.

In this work we develop a heuristic for VDJ sequence annotation that does not use alignments. This new heuristic is based on searching conserved regions in the source sequence to identify CDR3 regions. In practice this approach produces satisfying results with accuracy rate of 95% when applied to verified data sets.

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Forming a panel of markers for the molecular-genetic diagnosis of congenital
metabolic disorders
| Parseq Lab

student: Ekaterina Nebozhatko
scientific advisers: Tamara Simakova, Anton Bragin

Predicting the deleterious effects of mutation on protein function is one of the main tasks of genetics. Often researchers use predictive tools for this. The main problem with the use of predictive tools is not enough high sensitivity and specificity of classifiers. On average, the sensitivity is 80%, which means that 20% of the possible pathogenic mutations may go unnoticed. This can adversely affect the success of treatment. Another approach is to use open databases in which information on pathogenic mutations for certain genes is collected and verified.

The company Parseq Lab is working on a large project to create a panel of markers. It included 37 genes associated with 35 different diseases and 36 external sources. In this paper, a part of the project with single database PNDdb and three genes GCH1, QDPR and PTS is presented. In the course of the work, a tool was implemented that exports the necessary data from the site and presents them in the VCF format. The sensitivity of predictive tools of SIFT and PolyPhen was also assessed.

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Khazars heritage in the world genomes | University of La Verne

student: Yury Orlov
scientific adviser: Tatiana Tatarinova

Khazars are a semi-nomadic ethnic group that lived in the second part of the 1 st millennium, occupying a large area north of Caucasus between Black and
Caspian seas. At the end of the 10 th century their state was destroyed and the Khazar Khanate disappeared as suddenly as it rose, without leaving any legacy
except their own funerary mounds. At all times there were pretty much theories and guesses about the Khazars origin and their descendants but it was impossible to make solid conclusions about them. The aim of this project is to find the answers on the questions of Khazars origin and genetic legacy by
analysing ancient DNA (aDNA) extracted from remains of three Khazar representatives.

In course of the project, aDNA sequencing data was processed according to its specific library preparation and degraded nature of aDNA. Reads were
mapped to the HG38 reference genome. It was found that bacterial contamination was more than 75% (typical to aDNA), and by detecting significant amount of C-T transitions on the read ends it was shown that studied DNA is indeed of ancient origin. Using the GATK package we performed the SNP-calling procedure on obtained data and with Admixture tool figured out that the Khazars are a mix of North East Asians, Northern European, Mediterranean and South West Asian populations, as it is expected of a well-mixed group of semi-nomadic people.

As continuation of the work we are collecting different ancient and modern genomes to compare obtained data to them and finally draw a conclusion about the Khazars origin and their descendants in the modern world.

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Russian Exomes. Part 1. |Bioinformatics Institute

students: Olga Poleshchuk, Ekaterina Izmailova
scientific adviser: Yury Barbitoff

Mutations in protein-coding part of the genome are a cause of numerous different pathologies. Thus, whole exome sequencing (WES) is a commonly used alternative to whole-genome sequencing in medical genetics and health-related studies. Some environmental adaptations also likely arose from changes in protein-coding regions, making exome sequencing a valuable tool for population genetics studies. Several large sequencing consortia (e.g., Exome Aggregation Consostium (ExAC)) have collected data from hundreds of thousands samples of western population, and a lot of research was done using this data. The goal of our project was to develop a pipeline for variant analysis in Russian population, and apply it to ~570 WES samples.

Firstly we created pipeline using Snakemake as one of possible tools for creating workflows. The pipeline receives raw FASTQ files as input and outputs a combined annotated VCF for all samples in a batch. We successfully tested our pipeline, and performed preliminary analysis of variants in a dataset of 570 samples of Russian and CIS ancestry. We observed many novel variants common to samples included in the study, with most of such variants classified as missense mutations, intronic variants, and synonimous substitutions. Thus, we made a very first and preliminary steps in assessing the exome-wide genetic structure of Russian population. Further data aggregation and analysis will help to completely fill the biggest gap on the genetic map of the world.

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Speed-efficient data structures for cloudSPAdes |Center for Algorithmic Biotechnology, St. Petersburg State University

student: Evgen Polevikov
scientific advisers: Anton Bankevich, Ivan Tolstoganov

GemCode technology that was recently introduced by 10X Genomics company is rapidly becoming essential for variant calling, diploid genome assembly and read alignment. The cloudSPAdes algorithm was recently developed in the Center for Algorithmic Biotechnology. The algorithm uses GemCode data to improve metagenome assembly quality. Currently, cloudSPAdes consumes a large amount of computational resources for assembly of complex metagenomes. CloudSPAdes' assembly procedure consists of several stages: on the first stage it constructs assembly graph using procedures which were implemented in already existing metaSPAdes pipeline. Then barcoded reads are aligned to the edges of the graph such that for every edge we get a particular set of barcodes. Every set is represented as a sorted array. Intersection of these sets is computed in order to estimate genome distance between long edges and determine their true ordering.

In this work we adapted probabilistic data structure called containment min hash that allows to improve current procedure of computing of edge intersection. In order to estimate intersection of two sets of barcodes A and B (assume that size of A less than size of B) we first create a bloom filter from the set of a larger size B. Then we take a random sample S from the set of a smaller size A and test every element of S for membership in B using a bloom filter. By that we estimate an intersection of A and B.

In order to benchmark containment min hash against the original sorted array data structure we constructed assembly graph from GemCode library which was sequenced from a mixture of 5 known bacterial species. We selected a set of 1492 edges longer than 5,000 bp from the assembly graph and found an intersection for every ordered pair of these edges using containment min hash and compared it with initial edge intersecting procedure. Our analysis have shown that new algorithm works approximately 6 times faster. Also we have managed to decrease memory consumption: now it is enough to store about 60% of data that initial procedure uses.

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Protein digestion patterns|University of North Carolina at Chapel Hill

student: Natalia Rodina
scientific advisers: Popov Konstantin, Dokholyan Nikolay

Digestion of the proteins by proteasomes and proteases in cells results in producing a specific repertoire of peptides that can potentially bind to MHC 1 complex 1 and used for triggering immune response against specific cancer cells. Thus, creating a tool for prediction the "peptide profiles" produced by protease cleavage in different types of tissues in normal cells and primary tumor became the aim of the present project.
In the first step, microarray expression data in 19 types of tissues types for normal cells (726 arrays) and primary tumor (1.460 arrays) was collected from the MERAV database. PCA analyzes of the preprocessed expression data showed differences in normal tissue and primary tumor for every tissue type were shown. For every tissue type, expressed genes were selected (values higher then median of quintile normalized data) and only genes expressed in the primary tumor and not presented in the normal tissues were taken into account. For selected genes, the amino acid sequences were parsed from the NCBI protein database.
Information about cleavage sites of human cell proteases was downloaded from the Merops database and for every type of tissue only expressed proteases were selected.
In the next step, a tool for prediction of the peptide profiles was created. As input, the tool takes a selected type of the tissue. Then, from inbuilt database, amino acid sequences of all genes and information about cleavage sites of all proteases expressed in the selected tissue are taken. The tool finds all possible cleavage sites in every protein for every protease and provides information about all peptides created by the cleavage of all proteins in the tissue.
The created tool will provide the possibility to predict peptide profiles for all tissue types and identify peptides that are specific for the cancer cells and can be used for targeted immune therapy.


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Ti plasmid evolution and horizontal gene transfer | St. Petersburg State University

students: Shikov Anton , Zorin Evgeniy
scientific advisers: Alexandr Tkachenko, Mikhail Rayko

Agrobacterium species contain special sequence named T-DNA in Ti- and Ri-plasmids which can be inserted into plant genome. This feature is widely used in plant biotechnology. However, this insertion can become a stable part of plant genome, thus, Agrobacterium species are able to implement horizontal gene transfer to plant organism that happens quite rare in plant realm.

The aim of our work was to detect of new examples of horizontal gene transfer in plants and reconstructing phylogeny and evolution of Ti- and Ri-plasmids. To achieve this goal, we used hmmer tools and analyzed available plant genomes and proteomes. In total, 66 proteomes and 45 genomes were scanned. Extracted hits were further utilized for making multiple alignments and building approximately 700 trees.

Unfortunately, we didn't detect any explicit clusterization of plant and bacterial sequences. Nevertheless, during analysis we successfully revealed a brand-new example of horizontal gene transfer in Nicotiana tabacum that has not been described in literature before. Bacterial protein riORF20 from Agrobacterium rhizogenes has two plant homologs. Interestingly, this two proteins are homologous to C- and N-ends of riORF20 respectively. For this reason, we propose DNA recombination in N. tabacum after T-DNA insertion.

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Enhancement of Export Option for a Genome Mappability Score Estimator | Bioinformatics Institute

student: Skalon Elizaveta
scientific adviser: Bakin Evgeniy
Mappability is a genome-wide function that indicates whether it is possible for any read to be unambiguously mapped to a given position. Mappability information can be crucial for an interpretation of such experiments as ChIPSeq, SNP-calling etc., where quantitative estimates or confident identification of variations are performed. There is a special metric called Genome Mappability Score (GMS), which quantifies the mappability. GMS measures a weighted probability of mapping certainty in a given place. If the GMS is zero in a given position, many identical reads from different loci may be equally mapped to this region. Otherwise, if the GMS is 100, a read mapped to this position is unique.

In this work, we extended the functionality of fast and sufficiently accurate instrument for the GMS calculation, developed by in Bionformatics Institute in 2016. Firstly, a possibility to get output records in many various formats was provided. It allowed not only Wig and BigWig, but also BED, BigBed and TDF output formats to be supported. Secondly, the runtime of data export was reduced by an implementation of a multiprocessing mode, geometric expansion of arrays and export of GMS track directly to BigWig without wigToBigWig converter.
These improvements made the GMS computation even more convenient and friendly for its users.

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Retention time for identification of natural products | Carnegie Mellon University

student: Vladimir Sukhov
scientific adviser: Alexey Gurevich, Husein Mohimani

Natural Products (NPs) play an important role in pharmacology: many antibiotics, antiviral and antitumor agents are NPs. Thus, it is crucial to have methods for accurate discovery of new NP. In the process of searching for new NP, false positive identifications may occur. To reduce their number, we use retention time (RT) as an additional correctness check for discovered NP.

In this work, we applied machine learning methods for determining possible RT range for peptides. The multiple regression method was chosen as the primary technique. As a model for machine learning, we considered the amino acid composition of a peptide, where each amino acid adds its own weight to the final RT value.

As the result, the model was trained and tested. Model benchmarking demonstrated high accuracy of RT prediction and its potential for a significant reduction of false positive identifications.

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Analysis of VH-replacement statistical properties based on public datasets | Center for Algorithmic Biotechnology, St. Petersburg State University and Pavlov First St. Petersburg State Medical University

students: Adel Gazizova, Anastasia Vinogradova
scientific adviser: Andrey Slabodkin, Maria Chernigovskaya, Oksana Stanevich

During a construction, immunoglobulin H locus (IgH) undergo a process named VDJ-recombination, during which is random gene segments from IgH germline are set into resulting gene sequence. It provides a primary specificity to antigens. However, infrequently, the existing V-gene can be partly replaced by a new one, and this process is called VH-replacement. There are various hypotheses regarding the contribution that VH-replacement makes to antibody functionality.

In our work, we created a pipeline, which allows to identify VH-replacement in human antibody sequences. First we downloaded the data from Genbank, parsed files and extracted titles, that contained all the information about each sequence. Before starting the search, we divided antibody sequences into clonal families, because our data must contain only clonal-independent sequences in order to exclude a false-positive result. Then by means of developed script we made an exact and inexact (with one possible mismatch) search of VH-replacement's footprints in sequences of people with different phenotypes. We analyzed results and found, that VH-replacement frequency significantly increases for subjects infected with HIV-1, as well as for ones vaccinated against pneumococcus.

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Web bot development for automation of requests to IMGT / V-quest | Bioinformatics Institute

students: Andrey Zolotarev, Alexandr Cheblokov
scientific adviser: Evgeniy Bakin

There are a lot of different web-services that give the user an opportunity to work with integrated databases and research tools, which are necessary for a number of scientific areas.

One of them is IMGT® (the international ImMunoGeneTics information system®) – high-quality knowledge resource in immunogenetics and
immunoinformatics that specifically provides data about immunoglobulin or antibodies, T-cell receptors, major histocompatibility (MH) of human and other vertebrate species, immunoglobulin superfamily, MH superfamily and related proteins of the immune system of vertebrates and invertebrates. Unfortunately, this service is difficult to use for implementation statistical analysis due to limitation of loadable
sequences. IMGT allows the user to load only 50 sequences by one request, and the task become further complicated by the need to configure multiple query parameters.

The problem for statistical research is obvious, the scientist must spend a huge amount of time to process even one thousand sequence dataset.

The solution we developed is web-bot that allows the researcher to automate the processing of large amounts of data subject to the limitation given above. We came to the conclusion that a suitable basis for our objective is Selenium Web-Driver.
Selenium is a software library with the open source code, which is widely represented for a number of the most popular web browsers and compatible with such popular programming languages as C#, Python, JavaScript and others. This module emulates user behavior on the site, what allows to set parameters once and then implement the repetition of their setting by Selenium API.
As a result of our work we present the program that automates requests to IMGT for huge datasets and includes an interface for configuring the search parameters that are specific to a particular task. Result of program execution is a table in CSV-format that contains data required for the researcher.

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Using approximate calculations to speed up the peak calling procedure |Bioinformatics institute

student: Viacheslav Borovitskiy
scientific adviser: Evgeniy Bakin
Peak calling is a computational procedure used to identify areas in a genome that have been enriched with aligned reads primarily as a consequence of performing a ChIP-sequencing experiment. There are several popular pieces of software which perform this procedure (most of them require substantial computational resources and time). Each one has its own set of parameters requiring adjustment to the particular experiment.

In this work, we try to address the issue of time costs of the process of parameters adjustment for the peak calling procedure. We present a prototype of a tool that uses some fast machine learning / digital signal processing methods to approximately obtain the result of a peak calling procedure for a given caller with a given set of parameters in a matter of no time.

At first, we use given caller with a given set of parameters on a small piece of data. We then use the results of the previous step to train a linear
classifier (some fast time-series optimized version of logistic regression).

Finally, we apply our trained classifier (followed by some threshold transformation) to the rest of the data to obtain an approximation of the result.

We test our tool against some data sets from the Encyclopedia of DNA Elements (ENCODE). On "good" data we have precision/recall scores at about 0.85/0.85. On "bad" data we have precision/recall scores at about 0.20/0.20. Tests give impression that we never overfit, meaning that precision/recall scores on the train set determine those on the test set.

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Regulatory network modeling based on analysis of ATAC-seq data from cancer cells | Institut Cochin, Laboratory "Computational Epigenetics of Cancer"

student: Anastasia Danchurova
scientific adviser: Valentina Boeva

The tumor cell state is governed by complicated interplay between transcription factors that regulate gene expression and thus define cell fate. The concept of core, or master, transcription factors comprising Oct4, Sox2, Nanog (also known as Yamanaka's factor family) postulates that small number of transcription factors control the more numerous auxiliary transcription factors and play an essential role in determining of cell fate. Recent data showed that these core transcription factors play a regulative role in different types of cancer.

Because cancer is a disease associated with aberrant gene expression patterns, transcription factors, which serve as the convergence points of oncogenic signaling and are functionally altered in many cancers, hold great therapeutic promise. The more personal this therapy will be the more efficient result it will achieve.

That is why in this project exactly ATAC-seq data is used. Related to DNAse-seq and MNAse-seq methods, ATAC-seq compares favorably in library preparation simplicity, speed and amount of required cells (500-50 000 cells), what in total makes it the appropriate for clinical usage.

In this project, we create a tool, which combines ATAC-seq data with human genome annotation and several databases, determines interactions between transcription factors and active promoters and enhancers. As a result, we are expecting to construct a graph that will represent all detected interactions. Analysis of such graph is intended to help to determine the main transcription factors that may become effective potential targets for anti-cancer therapy.

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Regulatory network modeling based on analysis of ATAC-seq data from cancer cells |
All-Russia Institute for Agricultural Microbiology

student: Yury Malovichko
scientific adviser: Evgeniy Andronov

Sinorhizobium meliloti is one of the so-called Rhizobia, a group of α- and β-proteobacteria known for their capability of interacting with legume plants that results in stable mutualistic symbiosis where bacteria provide plants with atmosphere nitrogen reduced to ammonium in exchange for organic carbon. The genome of Rhizobia differs from that of Escherichia coli and other model prokaryotes and comprises of one major chromosome and one or more symbiotic plasmids that determine bacterium's host range and symbiosis efficacy. However, Rhizobia genome is also known for its flexibility, with symbiotic genes rearranged with plasmids, between them or even between plasmids and chromosome.

In this study, we aimed to prove a suggestion based on RFLP and other molecular marker analyses that two distinct genetic lines exist with S. meliloti species discriminated by linkage of particular alleles of leu and betCB genes. We used MLST approach with 10 loci suggested previously for genomic clustering of this species (see Reference) ad Bayesian Inference algorithm to build a tree that would show actual phylogeny of 12 isolates with 6 isolates for both supposed genomic lines, respectively. However, we gained ambiguous results showing that suggested loci are evidently not universal in their use for MLST of S. meliloti. For now, we seek for more informative loci that will shed the light on true phylogeny of
these isolates and existence of these two genomic lines.

1. Berkum P. Van, Elia P., Eardly B.D. Multilocus sequence typing as an approach for population analysis
of Medicago-nodulating rhizobia // J. Bacteriol. 2006. Т. 188. № 15. С. 5570–5577.

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NGS-based metagenomic pathogen viruses and bacteria identification system |
Saint-Petersburg Pasteur Institute

student: Alexandr Bebyakov
scientific adviser: Alexandr Semenov

Большинство методов микробиологической диагностики занимают продолжительное время и неприменимы для обнаружения некультивируемых форм патогенных агентов. Предполагается возможным на основе данных секвенирования нуклеотидных последовательностей смешанного образца определять наличие возбудителей особо опасных инфекций и свойственных им факторов патогенности и, таким образом, ускорять процесс принятия решений о мерах противодействия возможным эпидемиям.

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Applying state-of-the-art neural network architectures for predicting protein-binding sites |
ITMO University

student: Viacheslav Borovitskiy
scientific adviser: Tatiana Malygina

This is a project aiming to improve an approach proposed in the paper by using some of the modern neural network architectures.

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Study and development of a macrophage metabolic model|ITMO University

student: Natalia Rodina, Alexandr Cheblokov
scientific adviser: Gainullina Anastasia, Sergushichev Alexey

Macrophages are cells of the first line of immune protection: destroy pathogens (M1), maintain tissue homeostasis (M2). Using the metabolic FBA model allows you to see the coordination between metabolic pathways at the level of the whole cell. However, the existing FBA model of macrophage metabolism has a number of inaccuracies, and therefore it does not reflect the latest ideas about their M1 activation, formulated during molecular biological experiments. The purpose of this project is to detect and correct inaccuracies of the macrophage FBA model of metabolism.

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Biogeography of arabidopsis|University of La Verne

student: Anton Eliseev, Kristina Krivonosova
scientific adviser: Tatiana Tatarinova

Цель проекта - с помощью геномов медикаго и арабидопсиса определить корреляции между генетикой, климатом, почвой и прочей географией. Построить модель связывающую окружающую среду и геном.

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Statistical analysis of annotated genomes|University of La Verne

student: Poleshchuk Olga, Danchurova Anastasia
scientific adviser: Tatiana Tatarinova

Find correlation between sequence features and functional regions in different genomes

  1. Plot sequence features such as TFBS, SNPs, methylation, RNA-seq coverage
  2. Map it on promoter regions
  3. Find correlation
  4. Consider outcomes for promoter prediction for complex and not annotated genomes

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Finding novel variations of germline Immunoglobulin genes using WGS data|University of California San Diego

student: Alexandr Ilin
scientific adviser: Yana Safonova

Variety of immunoglobulin germline genes (V, D, and J) is a key component of the antibody repertoire diversity. Highly repetitive structure of Ig loci and a lack of natural selection result in elevated polymorphism rate of immunoglobulin germline genes. In this project, we want to analyze variations of Ig loci in several human populations and describe differences between them.

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Long read mapping improvements for Flye assembler|University of California San Diego

student: Evgeny Polevikov
scientific adviser: Mikhail Kolmogorov

minimap2 is a versatile pairwise aligner for genomic and spliced nucleotide sequences written in C. The goal of this project is to write C++ wrapper for this tool in order to incorporate it into Flye.

In src/example.cpp you can find an usage example of minimap2 API with C++ interface. The example shows how to build an index and how to use this index to find overlaps for pacbio reads.

We have recently released Flye assembler for long and noisy reads (PacBio, Oxford Nanopores). The assembly results seems to be very promising in comparison with the current state-of-the-art approaches.

As a successor of the ABruijn assembler, Flye uses solid k-mer based approach to find overlaps between noisy reads, which is (relatively) fast, but might be not optimal in terms of memory usage and the parameter choice flexibility. On the other hand, minimap2 seems to be very memory efficient, while showing the best sensitivity/specificity among the other long read aligners. As minimap2 also has C++ API, we want to explore the possibility of replacing our solid k-mer approach with minimap2. We expect that this change will significantly reduce the memory usage bottleneck, while also improving the assembly accuracy.

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Mediation of effects of persistent chemicals on the human sperm epigenome|A.N. Belozersky Research Institute of Physico-Chemical Biology, Moscow State University, Institute of Bioengineering, Research Center of Biotechnology RAS

student: Julia Kornienko
scientific adviser: Oleg Sergeev, Yulia Medvedeva

Процессы сперматогенеза и созревания сперматозоидов включают в себя каскад эпигенетических изменений (Wu et al., 2015). Изучение эпигенома сперматозоидов представляет очень перспективное направление по нескольким причинам. Во-первых, явно недостаточно изучено специфическое воздействие разнообразных факторов среды, включая химические факторы, на эпигенетические маркеры. Во-вторых, выявляемые эпигенетические изменения связаны с качеством и количеством сперматозоидов. И, в-третьих, что может быть особенно важно - репрограммирование эпигенома половых клеток может быть передано следующему поколению, что может привести к нарушению развития потомства, как на этапе развития эмбриона, так и в последующей жизни.

- Объект заявляемого молекулярно-эпидемиологического исследования – данные метилирования ДНК сперматозоидов (WGBS и RRBS) и данные факторов окружающей среды, полового развития и образа жизни, полученные в ходе родительского проспективного когортного исследования «Russian Children's Health. Male Reproductive SubStudy», начавшегося в 2003 году.

- Что известно из родительского исследования?
Воздействие таких стойких токсикантов, как диоксины, в течение полового развития (пубертата) влияет как на метилирование ДНК сперматозоидов (Pilsner et al., 2018), так и на снижение качества семени (Minguez-Alarcon et al., 2017) в возрасте 18 лет.

- Что неизвестно?
Какой вклад вносят другие факторы окружающий среды, потенциально негативно влияющие в процессе сперматогенеза на эпигеном сперматозоидов и качество семени, в частности курение.
Какой вклад в изменение эпигенома и качества сперматозоидов вносят различные варианты полового развития (ускоренное, нормальное, замедленное)?

- Цель исследования:
Изучить роль курения и темпов полового созревания в качестве медиаторов влияния диоксинов на метилирование ДНК сперматозоидов.

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Role of protein dimerization|Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill

student: Orlov Iurii
scientific adviser: Nikolay Dokholyan

We would like to understand why nature evolves proteins to function as dimers. To understand whether the oligomeric structure of protein is more evolutionary preferable than monomeric.

General plan:
  1. detect core residues (CR) responsible for structure formation
  2. determine how number of CR grows with protein length
  3. compare obtained results with dimeric proteins
  4. go further for larger oligomers (n-mers) to find the most preferable n

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Model of the N1 zone formation in human antibodies dimerization|Bioinformatics institute

student: Elena Pazhenkova
scientific adviser: Evgeniy Bakin, Oksana Stanevich

The N1-zone is a variable region of human antibodies DNA, formed as a result of VDJ-recombination and providing diversity of antigen binding regions. N1-zone generation is a complicated process including formation of palindroms on 5' and 3' ends and addind up to 20 random nucleotides to 5' and 3' ends with following non-homologous end joining. Thus, length of N1-zone depends of several random events. However, the N1-zone sometimes contains so-called footprints, appeared as a result of VH-replacement and recent studies showed that the length of CDR3 (including V3', N1, D, N2 and J5') is correlated with number of footprints (Meng et al., 2014). In this project we want to figure out whether VH-replacement is a random event by fitting of statistical model of N1-zone formation and estimating its parameters using Maximum Likelihood method.

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Search for multiple associations in GWAS data|Bioinformatics institute

student: Shikov Anton
scientific adviser: Yury Barbitoff

В 2017 году Биобанк Великобритании сделал крупнейший релиз генетических данных в истории (500,000 человек). Группа Бенджамина Нила произвела быстрый массовый анализ ассоциаций (GWAS) с более чем 2,000 фенотипов, результаты данного анализа были выложены в открытый доступ. С тех пор, огромное количество препринтов, посвященных поиску интересного сигнала в этих данных, появились на сервере bioRxiv. Данный проект посвящен поиску маркеров, обладающих множественными ассоциированными фенотипами, и изучению механизмов, опосредствующих данные эффекты.

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Identifying differentially expressed transposons across four life-cycle stages of Fasciola hepatica|Institute of Cytology RAS

student: Elisaveta Scalon
scientific adviser: Anna Soloveva, Nikolay Panyushev

Проект предполагает поиск мобильных элементов, чей уровень экспрессии варьирует в зависимости от стадии жизненного цикла Fasciola hepatica.
У F.hepatica секвенированы транскриптомы всех стадий жизненного цикла, данные доступны в Sequence read archive. Планируется собрать транскриптомы по референсу, выявить последовательности мобильных элементов
и определить их уровни транскрипции. На выходе будут получены данные о наличии или отсутствии мажорных транскриптов мобильных элементов, специфичных к отдельным стадиям жизненного цикла F.hepatica.

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Evolution analysis of genes associated with apomixis in Brassicaceae family|CAB SPbU

student: Rostislav Skitchenko
scientific adviser: Mike Raiko

Goals:
  • Perform a comparative phylogenetic assay of the genomes of seven plants.
  • Find the patterns between specific genes and apomixis plant-forms.
  • Find orthologous genes in other representatives of the Brassicaceae family.
  • Build the trees of genes of interest.

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