L’hypertriglycéridémie (HTG) correspond à une accumulation des lipoprotéines riches en triglycérides (LRTG) dans la circulation plasmatique, conséquence d’une augmentation de leur synthèse ou plus classiquement décrit, d’une diminution de leur catabolisme. Dans près de 50% des cas, aucune cause génétique n’est identifiée chez les patients présentant une présentant une HTG sévère, aussi bien dans le cadre du syndrome de chylomicronémie familiale (FCS) que dans celui du syndrome de chylomicronémie multifactorielle (MCS). Pour améliorer nos connaissances et la caractérisation de ces patients, la conduction de corrélations phénotypes-génotypes précises grâce à une collaboration clinico-biologique étroite, ainsi que le développement d’outils de diagnostic moléculaire performants, demeurent un enjeu majeur. Premièrement, l’évaluation de la concentration pré-héparinique en LPL et l’activité post-héparinique 60 minutes après l’injection d’héparine chez 62 patients MCS caractérises génétiquement a permis la mise en évidence deux sous-groupes chez ces patients. Deuxièmement, le développement d’une stratégie séquençage de nouvelle génération permettant d’explorer simultanément les 9 gènes les plus prévalents dans les hypercholestérolémies, les hypocholestérolémies et les hypertriglycéridémies, a permis de détecter les variants nucléotidiques avec une sensibilité équivalente au séquençage Sanger mais aussi de détecter des grands réarrangements. L’ensemble des résultats souligne la complexité des mécanismes de régulation du métabolisme des LRTG et l’intérêt de l’étude des interactions gène-gène. Ainsi, ces travaux ont permis de mettre en évidence de nouvelles hypothèses à explorer pour la compréhension des mécanismes physiopathologiques des HTG sévères et d’améliorer les outils disponibles pour les études de corrélation génotype-phénotype / Hypertriglyceridemia (HTG) correspond to an increase of triglyceride-rich lipoproteins (TGRL) circulating concentration, as a consequence of an increase in the synthesis of or a decrease in their catabolism, most classically described. In nearly 50% of patients with severe hypertriglyceridemia (HTG), no genetic cause is identified, either in familial chylomicronemia syndrome (FCS) or in multifactorial chylomicronemia syndrome (MCS). To gain new insights and to improve patient’s characterization, it remains important to conduct accurate phenotype-genotype association studies through close collaboration with referent lipidologists, and to develop high-performance tools for molecular diagnosis. Firstly, the assessment of pre-heparin LPL concentration as well as LPL activity 60 minutes after heparin injection, enabled the identification of two subgroups within 62 genotyped MCS patients Secondly, the development of a new sequencing generation workflow exploring simultaneously the 9 most prevalent genes in dyslipidemia, allowed the detection of single nucleotide variations with sensitivity equivalent to Sanger sequencing, but also allowed the detection of copy number variations. Collective consideration of the results underlines the complexity of the regulation mechanisms of TGRL metabolism and the interest of gene-gene interactions study. Thus, the studies presented herein bring new hypothesis to explore for understanding the pathophysiological mechanisms of severe HTG and to improve molecular diagnosis tools available for phenotype-genotype association studies

La métamorphose des amphibiens est le processus rapide et irréversible par lequel un têtard aquatique se transforme en une grenouille respirant à la surface. Cette transition écologique, réminiscente de la période périnatale chez les mammifères, s'accompagne de changements spectaculaires (régime alimentaire, organes locomoteurs, système respiratoire...). Ces modifications morphologiques et physiologiques nécessitent la réponse concertée à un signal hormonal, les hormones thyroïdiennes (HT), de différents tissus vers des destin parfois opposés : apoptose (dans la queue), prolifération (dans les pattes), et remodelage (dans les intestins et le système nerveux central). Toutefois, la synchronisation de la réponse des différents tissus fait appel à d'autres signaux hormonaux, et notamment les glucocorticoïdes (GC). Ces derniers sont également les médiateurs principaux de la réponse au stress. Les processus endocriniens de la métamorphose et la réponse au stress sont fortement couplés. Les GC peuvent ainsi jouer le rôle d'interface permettant l'intégration de signaux environnementaux au niveau de réseaux de régulation. Dans le cadre de mon doctorat, j'ai analysé les transcriptomes des bourgeons de membres postérieurs et de l'épiderme caudal de têtards de Xenopus tropicalis traités ponctuellement avec des HT et / ou des GC. La comparaison de ces deux tissus a permis de caractériser la diversité des profils d'expression des gènes cibles des HT et des GC.Il en ressort plusieurs résultats majeurs. Tout d'abord, la diversité des profils d'interaction entre ces deux voies est limitée, et la majorité des types de profils sont communs aux deux tissus. Indépendamment du tissu, certains profils sont caractéristiques de fonctions biologiques spécifiques comme le remodelage de la matrice extracellulaire et le système immunitaire. Les gènes impliqués dans ces fonctions communes aux deux tissus sont cependant différents. Enfin, plusieurs facteurs impliqués dans la méthylation de l'ADN sont régulés par les deux hormones. / Amphibian metamorphosis is the rapid and irreversible process during which an aquatic tadpole transforms into an air breathing adult frog. This ecological transition, reminiscent of the mammalian perinatal period, comes with spectacular changes (diet, locmotor organs, respiratory system...). These morphological and physiological modifications necessitate the properly timed response to a single hormonal signal, the thyroid hormones (TH), in various tissues to lead them to sometimes opposite fates : apoptosis (in the tail), cell prolifération and differenciation (in the limbs) and remodeling (in the intestine and the central nervous system).However, TH do not act alone. In particular, glucocorticoids (GC) play important roles during this process. They also are the main mediator of the stress response. Endocrine processes of the metamorphosis and the stress response are deeply intertwined. GC can thus act as an interface to integrate environmental inputs into regulatory networks.During my doctorate, I analyzed the possible transcriptional crosstalks between TH and GC in two larval tissues : the tailfin (TF) and the hindlimb buds (HLB). Comparing these two tissues allowed me to caracterize the diversity of TH and GC target gene expression profiles. This resulted in several major results. First, the diversity of the profiles of crosstalk between these two pathways is limited, and the majority of the types of profiles is common to both tissues. Next, independently ofthe tissues, some profiles are caracteristic of spécific biological functions such as extracellular matrix remodeling and the immune system. Yet, the genes involved in these shared functions are different between the TF and the HLB. Finally, several factors involved in DNA methylation are subject to a crosstalk between the two hormones.

La caractérisation des réseaux trophiques est nécessaire pour comprendre le fonctionnement des écosystèmes et les mécanismes impliqués dans leur stabilité. Il est parfois difficile de déterminer les régimes alimentaires notamment pour des espèces discrètes et difficiles à observer comme les grands carnivores. Cependant, ces espèces jouent un rôle clé dans les écosystèmes dont elles influencent le fonctionnement et la biodiversité. Ainsi, connaitre le régime alimentaire des grands prédateurs avec précision est essentiel pour établir des stratégies de conservation. Diverses méthodes basées sur le monitoring, l'analyse d'échantillons invasifs ou non ont été utilisées pour étudier les régimes alimentaires. Elles sont généralement biaisées ou peu résolutives. Les méthodes basées sur l'identification des fragments d'ADN dans les fèces ont le potentiel de fournir une meilleure information, notamment dans le cadre d'une approche métabarcoding. Il s'agit de caractériser simultanément l'ensemble des espèces dont l'ADN est présent dans un échantillon environnemental, en utilisant les Nouvelles Techniques de Séquençage. Dans ce cas, les amorces universelles nécessaires pour amplifier toutes les proies potentielles amplifient également l'ADN du prédateur s'il y a proximité taxonomique (par exemple mammifères). Ainsi les produits PCR obtenus à partir des fèces sont essentiellement composés d'ADN du prédateur et ne reflètent pas l'ensemble du régime alimentaire. L'utilisation d'un oligonucléotide de blocage limitant spécifiquement l'amplification de l'ADN du prédateur peut résoudre ce problème. Nous avons développé une méthode de ce type basée sur l'utilisation d'amorces universelles pour les vertébrés (amplifiant la région 12SV5) et d'oligonucléotides de blocage. Bien que non quantitative, cette méthode s'est montrée robuste, adaptée à l'étude de prédateurs à très large spectre de proies, et très résolutive pour identifier les proies au niveau du genre et de l'espèce. Nous l'avons appliquée à l'étude du régime alimentaire du chat léopard (Prionailurus bengalensis) qui s'est avéré très diversifié (mammifères, oiseaux, amphibiens et poissons) dans les deux populations du Pakistan étudiées. Avec la même approche, nous avons démontré la réalité du conflit entre l'homme et le léopard commun (Panthera pardus) dont le régime est presque exclusivement composé d'animaux domestiques. Enfin, nous avons pu proposer des actions de conservations pertinentes après avoir montré que le régime de la très menacée panthère des neiges (Panthera uncia) est principalement composé d'ongulés sauvages. / Information on food webs is central to understand ecosystem functioning. It also provides information of ecosystem stability by evaluating the resource availability and use. Obtaining information on the diet can be critical especially when dealing with elusive carnivores, which are difficult to observe. However, these large carnivores are keystone species that influence the ecosystem through trophic cascades and maintain biodiversity. Thus, precise knowledge of their diet is a prerequisite for designing conservation strategies of these endangered species. Direct and indirect monitoring as well as invasive and non-invasive approaches that have been used to study the diet are either biased or have a low resolution. The DNA-based analysis of feces is an alternative method that may provide better information. It can be implemented through a metabarcoding approach, which is the simultaneous identification of multiple species from a single environmental sample containing degraded DNA by using Next Generation Sequencing. In this case, the use of universal primers for vertebrates amplifying all potential prey also amplifies the predator DNA when it belongs to a close taxon (e.g. mammals). Thus, the PCR products obtained from feces extracts will mainly consist of predator sequences and may not represent the full diet. The use of oligonucleotides specifically blocking the amplification of the predator DNA may overcome this problem. We have developed such a method based on the concomitant use of a universal primer pair (12SV5, amplifying all vertebrates) and blocking oligonucleotides for identifying the prey DNA fragments from predators feces. Even if the method developed is not quantitative, it is robust and adequate for studying predator with a very large dietary range and has a better resolution than traditional methods for identifying prey at the genus or species level. This methodology has been applied to characterize the highly eclectic diet (mammals, birds, amphibians and fishes) of two Northern-Pakistani populations of leopard cat (Prionailurus bengalensis). With the same approach, we demonstrated the importance of the Human-leopard conflict in Pakistan, due to the almost exclusive consumption of domestic animals by the common leopard (Panthera pardus). We could also highlight relevant conservation issues for the highly endangered and cryptic snow leopard (Panthera uncia), based on the fact that it mainly fed on wild ungulates.

O gene fator regulador de interferon 4 (IRF4), localizado na região cromossômica 6p25- p23, é um membro da família de fatores reguladores de interferon (IRF), um grupo de fatores de transcrição de ligação ao DNA, sendo IRF4 primariamente associado ao desenvolvimento e resposta imune e expresso exclusivamente em células do sistema imunológico e em linhagens melanocíticas. Embora muitos estudos tenham associado IRF4 a diversas condições, como melanoma e leucemia linfocítica crônica, um recente Genome-Wide Association Study (GWAS) identificou que alelos do SNP rs12203592 (intron 4) estão associados com variação fenotípica em relação à presença de sardas, pigmentação da pele, cabelos e olhos. Estudos funcionais realizados em células melanocíticas humanas e de camundongos revelaram que este SNP está diretamente envolvido na regulação da expressão de IRF4, sugerindo uma clara função na pigmentação do melanócito. Apesar destes achados, a diversidade das regiões regulatórias e codificadora de IRF4 não foi até o momento analisada em populações miscigenadas. A fim de avaliar se outros sítios de variação ao longo do gene IRF4 podem estar associados à pigmentação humana, as regiões regulatórias (promotora e 3´UTR) e codificadora (9 exons e regiões intrônicas flanqueadoras, incluindo o SNP rs12203592) foram analisadas por sequenciamento de nova geração em uma amostra miscigenada da população brasileira. A amostra populacional foi composta por 228 indivíduos não aparentados de Ribeirão Preto, estado de São Paulo, Brasil, os quais foram estratificados de acordo com a pigmentação da pele (clara, média e escura), olhos (azul, verde, castanho-claros e castanho-escuros), cabelo (ruivo, loiro-claro, loiroescuro, castanho-claro, castanho-escuro e preto) bem como em relação à presença de sardas e intensidade de cabelos grisalhos. Bibliotecas de DNA foram preparadas utilizando o Sistema de Enriquecimento de Alvo Haloplex (Agilent Technologies) e sequenciadas na plataforma MiSeq (Illumina). Os pacotes de software CutAdapt, BWA and GATK foram utilizados, respectivamente, para trimagem das sequências dos adaptadores, alinhamento e identificação de variantes. Haplótipos e alelos não identificados foram inferidos pelo método PHASE, embora a fase conhecida entre os sítios de variação (obtida pelo GATK) tenha sido levada em consideração. Um total de 105 sítios de variação foram identificados. Apenas dois deles apresentaram frequências genotípicas que não atendem ao esperado pelo equilíbrio de Hardy-Weinberg (EHW). Dezoito destes SNPs apresentaram forte associação a pelo menos uma característica de pigmentação. Entretanto, se a conservadora correção de Bonferroni para múltiplos testes for levada em consideração, apenas duas associações, ambas envolvendo o SNP rs12203592, permanecem significativas: a associação do alelo T com pele clara e olhos azuis. Este resultado está de acordo com estudos prévios, que reportam que o alelo rs12203592*T leva a uma menor ativação de IRF4 e a uma expressão reduzida da tirosinase, resultando em sensibilidade ao sol e olhos azuis. Foi inferido um total de 101 haplótipos, estando a distribuição destes de acordo com o esperado pelo EHW. Quando os haplótipos foram divididos em haplótipos da promotora, codificadora e 3´UTR foram observadas, respectivamente, 17, 29 e 37 diferentes combinações haplotípicas. Várias associações foram identificadas, particularmente envolvendo o haplótipo mais frequente da promotora, os dois haplótipos mais frequentes da codificadora e o haplótipo mais frequente da 3´UTR, todos associados com pele clara, olhos azuis, cabelos castanhos e cabelos grisalhos. Estes resultados sugerem que outras variantes além de rs12203592, quando consideradas em um contexto haplotípico, são associadas com a pigmentação humana. / The Interferon Regulatory Factor 4 (IRF4) gene, located at chromosomal region 6p25- p23, is a member of the interferon regulatory factor (IRF) family, a group of DNAbinding transcription factors, with the IRF4 primarily associated with immune system development and response and expressed exclusively in immune system cells and melanocytic lineages. Although many studies have shown that IRF4 is associated with many human conditions, such as melanoma and chronic lymphocytic leukemia, a recent Genome-Wide Association Study (GWAS) identified that alleles from the SNP rs12203592 (intron 4) is also associated with phenotypic variation regarding presence of freckles, hair, eye and skin pigmentation. Functional studies in human and mice melanin-containing cells revealed that such SNP is directly involved in the regulation of IRF4 expression, suggesting a clear role in melanocyte pigmentation. In spite of these findings, the regulatory and coding IRF4 diversities in admixed populations have not been evaluated so far. In order to verify if other variation sites spread across the IRF4 gene may be associated with human pigmentation, the regulatory (promoter and 3\'UTR regions) and coding (9 exons and flanking intronic regions, including the SNP rs12203592) regions were analyzed by next-generation sequencing procedures in a Brazilian admixed population sample. The population sample was composed of 228 unrelated individuals from the Ribeirão Preto area, São Paulo State, Brazil, which were stratified according to eye (blue, green, hazel, light-brown, and dark-brown), hair (red, blond, dark-blond, light-brown, dark-brown and black) and skin (light, intermediate and dark) pigmentation, as well as regarding the presence of freckles and intensity of hair greying. DNA libraries were prepared using the Haloplex Target Enrichment System (Agilent Technologies) and sequenced at the MiSeq platform (Illumina). CutAdapt, BWA and GATK software packages were used for trimming adaptor sequences, alignment and genotype calling, respectively. Missing alleles and haplotypes were inferred by using the PHASE method, although the known phase between variable sites (obtained by GATK) was taken into account. A total of 105 variation sites were identified. Only two of them presented genotype frequencies that did not fit Hardy- Weinberg equilibrium (HWE) expectations. Eighteen of these SNPs presented strong association with at least one pigmentation feature. However, if the conservative Bonferroni correction for multiple tests is taken into account, only two associations, both of them involving the rs12203592 SNP, remain significant: allele T associated with light skin and blue eyes. This result is in agreement with previous reports that the rs12203592*T allele leads to reduced IRF4 activation and reduced tyrosinase expression, leading to sun sensitivity and blue eyes. A total of 101 different haplotypes were inferred, and haplotype distribution was in agreement to HWE expectations. When haplotypes were subdivided in promoter, coding and 3\'UTR haplotypes, 17, 29 and 37 different haplotypes were observed, respectively. Various associations were identified, particularly involving the most frequent promoter haplotype, the two most frequent coding (only one of them with allele rs12203592*T), and the most frequent 3\'UTR, all of them with light skin, blue eyes, brown hair and hair greying. These results suggest that other variation sites besides rs12203592, when considered in a haplotypic background, are associated with human pigmentation.

The advent of Next Generation Sequencing (NGS), a little over a decade ago, has led to a vast and rapid increase in the generation of genomic data. The drastically reduced cost has in turn enabled powerful modifications that can be used to investigate not just genetic, but epigenetic, phenomena. Epigenetics refers to the study of mechanisms effecting gene expression other than the genetic code itself and thus, at the transcription level, incorporates DNA methylation, transcription factor binding and histone modifications amongst others. This thesis outlines and tackles two major challenges in the computational analysis of such data using techniques from machine learning. Firstly, I address the problem of testing for differential methylation between groups of bisulfite sequencing data sets. DNA methylation plays an important role in genomic imprinting, X-chromosome inactivation and the repression of repetitive elements, as well as being implicated in numerous diseases, such as cancer. Bisulfite sequencing provides single nucleotide resolution methylation data at the whole genome scale, but a sensitive analysis of such data is difficult. I propose a solution that uses a powerful kernel-based machine learning technique, the Maximum Mean Discrepancy, to leverage well-characterised spatial correlations in DNA methylation, and adapt the method for this particular use. I use this tailored method to analyse a novel data set from a study of ageing in three different tissues in the mouse. This study motivates further modifications to the method and highlights the utility of the underlying measure as an exploratory tool for methylation analysis. Secondly, I address the problem of predictive and explanatory modelling of chromatin immunoprecipitation sequencing data (ChIP-Seq). ChIP-Seq is typically used to assay the binding of a protein of interest, such as a transcription factor or histone, to the DNA, and as such is one of the most widely used sequencing assays. While peak callers are a powerful tool in identifying binding sites of sparse and clean ChIPSeq profiles, more broad signals defy analysis in this framework. Instead, generative models that explain the data in terms of the underlying sequence can help uncover mechanisms that predicting binding or the lack thereof. I explore current problems with ChIP-Seq analysis, such as zero-inflation and the use of the control experiment, known as the input. I then devise a method for representing k-mers that enables the use of longer DNA sub-sequences within a flexible model development framework, such as generalised linear models, without heavy programming requirements. Finally, I use these insights to develop an appropriate Bayesian generative model that predicts ChIP-Seq count data in terms of the underlying DNA sequence, incorporating DNA methylation information where available, fitting the model with the Expectation-Maximization algorithm. The model is tested on simulated data and real data pertaining to the histone mark H3k27me3. This thesis therefore straddles the fields of bioinformatics and machine learning. Bioinformatics is both plagued and blessed by the plethora of different techniques available for gathering data and their continual innovations. Each technique presents a unique challenge, and hence out-of-the-box machine learning techniques have had little success in solving biological problems. While I have focused on NGS data, the methods developed in this thesis are likely to be applicable to future technologies, such as Third Generation Sequencing methods, and the lessons learned in their adaptation will be informative for the next wave of computational challenges.

Introduction: RNA viruses are economically important pathogens of fish, and among these viruses, infectious pancreatic necrosis virus (IPNV) is of particular concern for the aquaculture industry, especially for farmed rainbow trout (Oncorhynchus mykiss) and Atlantic salmon (Salmo salar). This non-enveloped aquatic virus, which was first isolated in the UK in 1971, belongs to the family of Birnaviridae and has a bi-segmented dsRNA genome of about 6kb. IPNV is classified in 6 genogroups with correspondence to 10 known serotypes and an additional proposed genogroup of marine aquabirnaviruses (MABV). IPNV causes high mortality in fry and a reduced mortality in adult fish, respectively. Fish, which survive, can become carriers and this can lead to a clinical outbreak by releasing infective material into water or by vertical transmission via oocytes, milt and seminal fluids. Methods: This project aimed at determining the phylogeny and genomic changes of IPNV in Scotland by whole genome sequence analysis of IPNV isolates (diagnostic TCID50 supernatants) spanning 3 decades since 1982, using next generation sequencing technology. Viral RNA of IPNV culture supernatant (CHSE-214 and TO cell culture) was processed for next generation sequencing on an Illumina MiSeq platform. Library preparation was performed using the Nextera XT DNA Library Kit, prior to sequencing according to the manufacturer's MiSeq Reagent Kit v3 (150cycles) protocol. To optimize whole genome next generation sequencing for IPNV, we compared two RNA processing protocols, the Glasgow (GLAP) and the Goettingen protocol (GOEP) with focus on missing terminal nucleotides after a de novo genome assembly. Sequences were used to determine the phylogeny and selection pressure on the genome as well as a possible virus-host adaptation. Results: The results showed that both protocols were able to give full length genomes as well as genomes with missing terminal nucleotides. The phylogenetic analysis of 57 sequenced IPVN isolates shows that 78.95 % of the isolates group within genogroup V, which includes serogroup Sp and 5.26 % within genogroup I which includes serogroup Ja. Segment A of 15.79 % of the isolate grouped within genogroup III, which includes serotype Ca1 and Te but only 7.02 % of the segment B isolates grouped in the genogroup III. The remaining 8.77 % of segment B groups within genogroup II, containing the Ab serotype. Previous research has shown that residue substitutions at positions 217 and 221 in the major capsid protein VP2 have an impact on the virulence of the virus, leading to different virulence types: virulent (T217, A221), low virulence (P217, A221), avirulent (T217, T221) and persistent (P217, T221). Whole genome sequence results show that 58.93 % of the sequenced isolates belong to the persistent, 32.14 % to the low virulent type, only one isolate was of a virulent type and 7.15 % had not virulence assigned amino acid compositions in positions 217 and 221. The selection pressure analysis showed that especially VP2 is experiencing selection pressure in the variable region. In the VP1 protein we see two sites under positive selection pressure within specific motifs. VP5 showed positive selected sites mostly within the truncated region of the protein. Other proteins showed no particular interesting sites of selection. The codon adaptation analysis showed highest adaptation index for VP2. Besides VP5, which had an CAI index below one, therefore showing negative adaptation, other IPNV proteins had an CAI of barely above the value of 1. The dinucleotide abundance, focussing on CpG, showed that CpG is underrepresented in segment A and B. Discussion Phylogenetic analysis of the sequenced IPNV strains shows separate clustering of different genogroups. Genetic reassortment is observed in segment B showing a grouping within genogroup III and II although the segment A of these isolates was grouping exclusively within III. We found that over 50 % of the isolates belong to the persistent and over 30 % to the low virulent type, assuming that due to not sterilising vaccination these types were selected in the vaccinated population. The results from the CAI calculations indicate an adaptation of IPNV to its host. Together with the findings that CpG is underrepresented in IPNV it suggests that this leads to an immune escape. Especially since the selection pressure analysis showed positive selection in VP2 within the virulence determination sites of the protein, indicating that IPNV "tries" to downregulate immune recognition. The prevalence of mostly persistent type of isolates indicates together with the assumption of adaptation and immune escape that IPNV is evolving with the host in order to ensure survival.

La paléoparasitologie est l’étude des restes de parasites préservés dans des échantillons archéologiques et permet de mieux comprendre l’état de santé des populations anciennes et d’obtenir des informations d’ordre anthropologique ou ethnologique, sur les régimes alimentaires ou les conditions d’hygiène au quotidien. Les restes de parasites peuvent être retrouvés sous forme de macro-restes (vers ou larves), d’antigènes, d’ADN ou d’œufs. Cesderniers peuvent être particulièrement bien préservés au cours du temps car ils sont composés en partie de chitine, les rendant résistants aux processus de dégradation. L’observation microscopique de leurs caractéristiques morphologiques et micrométriques permet d’identifier les taxons au niveau du genre ou de la famille. Dans le cadre de cette thèse, plusieurs helminthes gastro-intestinaux, dont les œufs sont fréquemment retrouvés dans des échantillons archéologiques, ont été ciblés par une approche génétique. Il s’agit des vers plats Tæniasaginata, T. solium, T. asiatica, Echinococcus granulosus, E. multilocularis, Diphyllobothriumlatum, D. dendriticum et D. nihonkaiense, des nématodes Trichuris trichiura, Enterobiusvermicularis et Ascaris sp. et des douves Fasciola hepatica, F. gigantica, Dicrocoeliumdendriticum et D. chinensis.La méthode « aMPlex Torrent » permet de détecter, dans un grand nombre d’échantillons archéologiques, une faible quantité d’ADN de parasites. Cette approche combine la spécificité et la sensibilité de la PCR au haut-débit du séquençage de nouvelle génération. Plusieurs vestiges, provenant de périodes et de régions géographiques diverses, ont été analysés. Des résultats génétiques ont été obtenus pour des échantillons aussi anciens que 7200 BP. Nous avons par ailleurs obtenus les premières séquences anciennes de Taenia sp., Diphyllobothriumsp., Echinococcus sp., et les premières séquences européennes d’Enterobius vermicularis. Auvu de ces résultats, notre approche apparait comme étant complémentaire à la microscopie. / Palaeoparasitogy, the study of parasite remains from archaeological samples, is adiscipline that can highlight questions about the health status of the ancient populations. It can give important anthropological or ethnological information such as the diet and the hygiene conditions of past societies. The remains can be preserved as macroremains (worms or larvae),antigens, DNA or eggs. Because they are partially made of chitin, eggs of gastrointestinalhelminths resist well over time to the taphonomic degradation process. It is possible to distinguish between different families or genera of parasites by looking at the morphological features of eggs. However, since several taxa share common features, the determination is rarelypossible at the species level. For this thesis, several parasite species for which eggs arecommonly observed in archeological samples have been studied by a genetic approach. Westudied the tapeworms Tænia saginata, T. solium, T. asiatica, Echinococcus granulosus, E.multilocularis, Diphyllobothrium latum, D. dendriticum, and D. nihonkaiense; the nematodesTrichuris trichiura, Enterobius vermicularis, and Ascaris sp.; and the flukes Fasciola hepatica,F. gigantica, Dicrocoelium dendriticum, and D. chinensis.The “aMPlex Torrent” approach has been set up to detect minute amounts of DNA from parasites in multiple archaeological samples. This approach combines the specificity andsensitivity of PCR to the throughput of Next-Generation sequencing. Several samples have been analyzed by this approach. We obtained genetic results for samples as old as 7200 BP and from various geographical and archeological contexts. We obtained the first ancient DNA sequences for Taenia sp., Diphyllobothrium sp., Echinococcus sp. and the first European sequences forEnterobius vermicularis. Genetic analyses and microscopic observations appear to be complementary. Indeed, at least one taxon per sample was detected by one of the two approaches.

Les avancées des nouvelles techniques de séquençage (NGS) ont permis dans le cadre des études en écologie microbienne de passer de l'analyse de quelques centaines de séquences par étude à des centaines de millions de séquences. Cette différence quantitative des données produites a induit des différences qualitatives quant aux études réalisées. En effet, avec le changement du type de données, les approches classiques d'analyse ne peuvent être appliquées et il est devenu nécessaire de définir de nouvelles stratégies en tenant compte des contraintes que posent ces données. Alors qu'il était possible d'insérer classiquement quelques dizaines de séquences issues des techniques de première génération dans des phylogénies expertisées, le nombre de séquences généré aujourd'hui par les NGS à chaque expérience rend cette tâche irréalisable et nécessite la mise en place de nouvelles stratégies et l'utilisation d'outils adaptés. Par ailleurs, les outils disponibles d'analyse de la diversité microbienne adaptés aux amplicons de nouvelle génération, implémentent des approches probabilistes et/ou de recherche de similitude pour l'identification des séquences environnementales. L'approche phylogénétique quant à elle, bien qu'elle soit la plus robuste, n'est pas utilisée pour l'annotation taxonomique de ce type de données du fait de ses besoins en temps et en ressources de calcul. Au-delà de l'approche d'annotation taxonomique, les nouvelles techniques de séquençage posent également le problème de la qualité des séquences produites et son impact sur l'estimation de la diversité. Ainsi, ce travail de thèse avait pour objectif la définition d'une stratégie d'analyse bioinformatique de données de séquençage massif dans le contexte de l'étude de la diversité microbienne, en tenant compte des limitations imposées par les ressources informatiques actuelles (matérielles et logicielles) d'un côté, et de l'avantage des méthodes phylogénétiques par rapport aux autres approches d'annotation taxonomique. Ce travail a donné lieu au développement d'une chaîne de traitement proposant une série d'analyses allant des séquences brutes jusqu'à la visualisation des résultats, tout en replaçant les séquences environnementales dans un contexte évolutif. L'approche développée a été optimisée pour la gestion de gros volumes de données, et a été comparée en terme de précision d'affiliation aux autres approches communément utilisées en écologie microbienne. Les tests et simulations ont montré qu'à partir d'une taille d'amplicons de 400 pb, l'affiliation phylogénétique avait les meilleurs résultats mais aussi, que la qualité de cette affiliation différait selon la région hypervariable ciblée. La chaîne de traitements mise en place a ensuite été par implémentée dans un contexte de calcul à haute performance, notamment sur un cluster de calcul, pour proposer un service web dédié à l'analyse de la diversité microbienne. / The characterization of microbial community structure via SSU rRNA gene profiling has been greatly advanced in recent years by the introduction of NGS amplicons, leading to a better representation of sample diversity at a lower cost. This progress in method development has provided a new window into the composition of microbial communities and sparked interest in the members of the rare biosphere. Concurrently, the processing of such amount of data has become an important bottleneck for the effectiveness of microbial ecology studies, and a multitude of analysis platforms have been developed for the handling of these data. As implemented, these tools have a steep learning curve for the biologist who is not computationally inclined, as they require extensive user intervention and consume many CPU hours due to dataset analysis and complexity, which can present a significant barrier to researchers. Moreover, although phylogenetic affiliation has been shown to be more accurate for the taxonomic assignment of NGS reads, the existing tools assign taxonomy by either a similarity search or a probabilistic approach, with the phylogenies being restricted to samples' comparison. Beyond the taxonomic assignment, the new sequencing technologies also arise the problem of the quality of the generated sequences and its impact on the richness estimation. In this work, we aimed to define a strategy for the bioinformatic analysis of high-throughput sequences in order to depict the microbial diversity, taking into account both the limitations imposed by current computer resources (hardware and software), and the advantage of the phylogenetic methods over the other taxonomic annotation approaches. This work has led to the development of a pipeline offering a set of analyzes ranging from raw sequences processing to the visualization of the results, while replacing the environmental sequences in an evolutionary framework. The developed approach was optimized for managing large volumes of data, and has been compared in term of the accuracy of taxonomic assignment to the approaches commonly used in the field of microbial ecology. This pipeline was then used to the developement of a dedicated web server for high-throughput sequencing analysis, that relies on a computing cluster and performs large-scale phylogeny-based analyses of rRNA genes with no need for specialized informatics expertise, and uses the phylogenies for both the taxonomy assessment and the delineation of monophyletic groups to highlight clades of interest.

Os sarcomas uterinos são tumores mesodérmicos raros que compreendem cerca de 3% de todos os cânceres nesse órgão. Apresentam diversidade histológica, comportamento agressivo, disseminação precoce e altas taxas mortalidade. Recentemente, os carcinossarcomas (CS) foram reclassificados histologicamente como carcinomas. Neste trabalho, os CS foram incluídos na casuística tanto para fins de comparação de seu componente mesenquimal, como por ainda fazerem parte da maioria dos estudos sobre sarcomas de corpo uterino e também da última classificação da WHO (Word Health Organization). Devido à sua diversidade e raridade, não há consenso relacionado aos fatores de risco para pior prognóstico e tratamento adequados para esses tumores. Informações sobre seus perfis gênicos e proteicos poderiam contribuir na caracterização de marcadores moleculares que auxiliassem no diagnóstico e prognóstico desses tumores, bem como no entendimento de sua biologia e comportamento clínico. Assim, nos propusemos a avaliar a presença de alterações gênicas nesses tumores, utilizando um painel de 409 genes, oncogenes e supressores de tumor, frequentemente mutados em tumores sólidos. Para isso, foram selecionadas 66 amostras, das quais 14 foram sequenciadas, incluindo, 5 carcinossarcomas (CCS), 4 leiomiossarcomas (LMS), 4 sarcomas de estroma endometrial (SEE) e 1 adenossarcoma (ADS). As reações foram realizadas utilizando a plataforma Ion Proton System (ThermoFisher) de Sequenciamento de Nova Geração. Nas 14 amostras encontramos 27 LoF e 40 mutações missenses, numa média de 39 inserções e 52 deleções por amostra, totalizando 70 mutações. Dessas, 25 encontram-se no banco de dados COSMIC. Os genes mais comumente mutados em nossa amostragem foram: TP53 (50%), KMT2D (36%), ATM (29%), DICER1 (21%), PIK3CA (21%), TRRAP (21%). Nosso objetivo principal era encontrar mutações específicas para cada subtipo histológico, porém apenas os SEEs (PDE4DIP) e os CCS (ERBB4 e PIK3CA) tiveram mutações especificas. Em outra análise, observamos que todos os subtipos histológicos compartilham o gene KMT2D. Embora não tenha sido possível estabelecer um perfil mutacional para cada subtipo histológico avaliado, nossos resultados abrem perspectivas para uma nova linha de pesquisa nos sarcomas de corpo do útero e certamente contribuem para um melhor entendimento dessas neoplasias / Uterine sarcomas are rare mesodermal tumors that comprise about 3% of all cancers in this organ. They present histological diversity, aggressive behavior, early dissemination and high mortality rates. Recently, carcinosarcomas (CCS) were histological reclassified as carcinomas. Here, we have included them in our series for purposes of comparison of the mesenchymal component and also because these tumors still form part of both the majority of studies and the WHO\'s latest classification for uterine sarcomas (Word Health Organization). Because of their diversity and rarity, there is no consensus regarding the risk factors for poor prognosis and appropriate treatment for these tumors. Thus, information about their gene and protein profiles can help in the diagnosis and prognosis of these tumors, as well as in the understanding of their biology and clinical behavior. We performed the New Generation Sequencing of 14 samples of uterine sarcomas (5 CCS, 4 LMS, 4 SEE and 1 ADS, using the Ion Proton System platform (ThermoFisher).) Among the 14 samples, we found 27 LoF (loss of gene function) and 40 missense mutations, with a mean of 39 insertions and 52 deletions per sample, totaling 70 mutations, 25 described in the COSMIC database. The most commonly mutated genes in our sample were TP53 (50%), KMT2D (36%), ATM (29%), DICER1 (21%), PIK3CA (21%), TRRAP (21%).Our main objective was to find specific mutations for each histological subtype, but only SEEs (PDE4DIP) and CCS (ERBB4 and PIK3CA) had specific mutations. In another analysis, we observed that all the histological subtypes share the KMT2D gene, which will be studied in future analyzes. Others analyzes, using a custom panel, are necessary to understand these mutations and its biological implication in uterine carcinosarcoma and sarcomas

Algae are a group of highly diverse photosynthetic organisms found in variety of habitats. As the primary energy base in ecosystems, knowledge of the diversity and presence of certain algal lineages is paramount to our understanding of the trophic state of aquatic habitats. In recent years, the state of Florida has seen an increase of both marine and freshwater algal blooms. Similarly, filamentous algae have begun outcompeting vascular macrophytes throughout many of Florida’s springs as nutrient enrichment from anthropogenic sources increases. Traditionally, the Florida algal spring communities have been assessed using classic morphological methods, which may underrepresent the true biodiversity present. Therefore, the goal of this study was to conduct a more complete diversity assessment implementing next-generation sequencing techniques (NGS) with morphological analyses and culturing methods. While morphological methods identified a wide variety of algal taxa, belonging to 4 phyla (Bacillariophyta, Charophyta, Chlorophyta, and Cyanobacteria), next-generation sequencing techniques provided greater detail of the diatom community. This is particularly important as many diatom taxa are used as indicators of water quality. We noted discrepancies between these two methods, highlighting how NGS techniques may complement the use of morphological analyses when analyzing algal diversity in this system. Culturing methods also revealed the presence of two taxa new to science (Nodosilinea fontisand Brasilonema variegatus), indicating these springs may represent a potential source of novel cyanobacteria. Taken together, this study showcases Florida springs are rich in algal diversity and a combination of methods is required for more complete biodiversity assessments. Future studies implementing such methods will aid in the preservation and conservation of these ecosystems.