Frankia est une actinobactérie symbiotique de 8 familles de plantes actinorhiziennes. Elle est connue par sa capacité à fixer l'azote moléculaire. La taxonomie et la phylogénie du genre Frankia reste incomplète et à explorer. Les objectifs de cette thèse sont d'apporter des connaissances supplémentaires sur la position phylogénétique et l'évolution des différents groupes d'infectivité du genre Frankia. Dans un premier temps, une phylogénie moléculaire basée sur les gènes glnII, nifH, gyrB et des ITS 16S-23S de l'ADNr a été réalisée. Le résultat de cette étude souligne la présence de quatre groupes de Frankia : (i) le groupe 1 associe les souches infectives des Betulaceae, Myricaceae et Casuarinaceae ; (ii) le groupe 2 des microsymbiotes obligatoires associés aux Coriariaceae, Datiscaceae, Rosaceae et Ceanothus (Rhamnaceae); (iii) le groupe 3 de souches d'Elaeagnaceae, Rhamnaceae, Myricaceae et Gymnostoma (Casuarinaceae) et (iv) le groupe 4, à position ancestrale, renferme les souches atypiques non fixatrices d'azote et/ou non infectives. Le groupe 3 aurait émergé à partir du groupe 4, alors que les groupes 1 et 2 sont les groupes qui ont émergé plus récemment. Dans cette thèse, nous avons montré que la concaténation des séquences des trois gènes (glnII, nifH et gyrB) semble être un outil puissant pour une meilleure étude évolutive afin de contourner l'influence du phénomène de transfert horizontal des gènes sur la phylogénie du genre Frankia. Par ailleurs, nous avons remarqué que la faible variabilité génétique est associée à la régression de taille des génomes de Frankia et coïncide avec des transitions de mode de vie symbiotique et une répartition géographique restreinte (le cas des Frankia–Casuarina et des Frankia non cultivables du groupe 2). Dans un second temps, nous avons focalisé nos recherches sur le modèle Frankia-Coriaria. Nous avons défini quatre groupes de Frankia endosymbiotes et deux groupes pour les Coriaria en se basant sur les séquences de trois marqueurs, glnA (glutamine synthétase), dnaA (amorceur de réplication des chromosomes) et l'IGS nifD-K (l'espace intergénique entre les gènes nifD et nifK codant pour les sous-unités alpha et beta de la protéine molybdène-fer) pour les Frankia microsymbiotes et deux régions d'ADN, matK (maturase chloroplastique) et ITS1- 2 (ARNr 18S - ITS1 - ARNr 5.8S - ITS2 –ARNr 28S) pour la plante hôte. L'analyse phylogénétique de deux partenaires symbiotiques, Frankia et son hôte respectif, montre l'absence de cospéciation. Ce résultat est cohérent avec celui de dernier chapitre dont nous avons montré, pour la première fois, l'occurrence de Frankia compatibles avec Coriaria dans un sol tunisien, dépourvu de la plante hôte depuis plus de deux siècles. Ce résultat est un bon argument de l'indépendance de Frankia microsymbiote de la plante hôte Coriaria et met en question la non cultivabilité des Frankia du groupe 2 / Frankia is an actinobacterium best known for its ability to fix molecular nitrogen and infect the roots of 8 actinorhizal plant families. The Taxonomy and the phylogeny of the Frankia genus remain incomplete and have to be more explored. The objective of this thesis is to provide additional knowledge on the phylogeny and evolution of different Frankia groupes. Firstly, the molecular phylogeny based on the analysis of glnII, gyrB, nifH genes, and 16S–23S rRNA internally transcribed spacer (ITS) sequences was carried out. The result of this study emphasized the presence of four Frankia clusters: (i) cluster 1 for Frankia associated with Betulaceae, Myricaceae and Casuarinaceae (ii) cluster 2 contains Frankia microsymbionts associated with Coriariaceae, Datiscaceae, Rosaceae and Ceanothus (Rhamnaceae), (iii) cluster 3 for Frankia of Elaeagnaceae, Rhamnaceae, Myricaceae and Gymnostoma (Casuarinaceae) and (iv) cluster 4 including atypical Frankia strains that are non-infective and/or non-nitrogen-fixing was positioned at a deeper branche followed by groupes 3. While clusters 1 and 2 appeared to have diverged more recently. The present study demonstrates the utility of phylogenetic analyses based upon concatenated gyrB, nifH and glnII sequences to resolve previously unresolved or poorly resolved nodes and will help describing species among the genus Frankia. The variation of the average pairwise distance within and between the clusters allows us to suggest a gradual erosion of Frankia diversity concomitantly with a shift from saprophytic non infective/non-effective to facultative and symbiotic lifestyle. Then, we focused on the cluster 2 of non-culturable Frankia in general and special focus on Frankia associated with Coriaria. The absence of cospeciation between the uncultured Frankia microsymbionts and the disjunct actinorhizal Coriaria species has been shown. These results were obtained following analyze of three bacterial genes; glnA (glutamine synthetase), dnaA (chromosome replication initiator) and the nifD-K IGS (intergenic spacer between genes coding respectively for nitrogenase molybdenum-iron alpha and beta subunits) and two DNA region of the host plants; matK (chloroplast-encoded maturase K) and the intergenic transcribed spacers (nuclear-encoded 18S rRNA-ITS1-5.8S rRNA-ITS2-28S rRNA).This result is consistent with the last chapter in which we showed, for the first time, the occurrence of compatible Frankia with Coriaria in a Tunisian soil, devoid of the host plant for more than two centuries. This represents a first argument for the independence of Frankia nodulating Coriaria to their host plants

The thesis deals with processing of epoch-wise GNSS measurements from local geodynamic network Sněžník. Its aim is to evaluate the geodynamics in the area of Králický Sněžník Massif and to assess the capabilities of epoch-wise GNSS measurements to detect the geodynamic movements. Within the thesis the comprehensive processing of all the GNSS measurements observed between years 1997 and 2011 is realized using the reprocessed products of first IGS reprocessing Repro1. Bernese GPS software version 5.0 is used for all the processing.

This thesis investigates the major errors and processes affecting the performance of a viable, standalone point positioning technique known as single frequency Precise Point Positioning (PPP). The PPP processing utilises both single frequency code and carrier phase GPS observables. The mathematical model implemented is known as the code and quasi-phase combination. Effective measures to improve the quality of the positioning solutions are assessed and proposed. The a priori observations sigma (or standard deviation) ratio in the sequential least squares adjustment model plays a significant role in determining the accuracy and precision of the estimated solutions, as well as the solutions convergence time. An

A afiliação genérica de Fischerella e Hapalosiphon é problemática devido à instabilidade dos caracteres morfológicos. Os gêneros Fischerella e Hapalosiphon são diferenciados pela presença de tricoma multisseriado e uni ou bisseriado, respectivamente. Porém, geneticamente esses caracteres não se mostraram diacríticos para diferenciar gêneros. Estudos moleculares de linhagens isoladas de ecossistemas brasileiros são escassos para Fischerella e inexistentes para Hapalosiphon. Neste estudo, oito linhagens de cianobactérias, pertencentes à família Hapalosiphonaceae, isoladas de água doce e solos brasileiros foram caracterizadas morfologicamente e geneticamente e analisadas para a produção de substâncias bioativas. As análises morfológicas identificaram cinco morfotípos de Fischerella (CENA19, CENA161, CENA212, CENA213, CENA214) e três de Hapalosiphon (CENA63, CENA71, CENA72). As análises filogenéticas do RNAr 16S usando neighbor-joining (NJ) e máxima verossimilhança (MV) colocaram todas as linhagens isoladas em um agrupamento com alto suporte (reamostragens de 99% NJ e MV) contendo membros da ordem Nostocales. Além disso, as linhagens de Fischerella selecionadas para o estudo agruparam-se em um clado interno com alto valor de reamostragem (100% NJ e 86% MV), com exceção da Fischerella CENA19. A posição dessa estirpe na árvore filogenética indica que necessita de revisão taxonômica. As linhagens de solo Hapalosiphon CENA71 e CENA72 também formaram um clado interno separado (99% NJ e 98% MV), mas a linhagem de água doce CENA63 foi colocada em um clado diferente (com valores de reamostragens de 99% NJ e MV), juntamente com linhagens do gênero Hapalosiphon e Westielopsis prolífica SAG 16.93, oriundas de solo. A comparação das análises filogenéticas individuais de regiões dos genes RNAr 16S, rpoC1, rbcL, tufA, e cpcBA-IGS das três linhagens de Hapalosiphon e de duas linhagens de Fischerella, CENA19 e CENA161, mostrou resultados incongruentes devido as diferentes taxas evolutivas desses genes. No entanto, a análise filogenética concatenada desses genes, mostrou que a Fischerella CENA19 agrupou com as duas linhagens de Hapalosiphon CENA71 e CENA72, com alto valor de reamostragem (100%), enquanto que a Fischerella CENA 161 e a Hapalosiphon CENA63 posicionaram-se cada uma em clados separados. Os resultados indicam que a nomenclatura das linhagens de cianobactérias da família Hapalosiphonaceae necessita de revisão. Os extratos intra e extracelulares das linhagens Fischerella sp. CENA161 e CENA19 e Hapalosiphon sp. CENA71 e CENA72 mostraram efeitos inibitórios no crescimento de bactérias patogênicas. As análises em espectrômetro de massas Q-TOF MS/MS indicaram a putativa presença de aeruginopeptina, cianopeptolina, fischerelina, aeruginosina, oscilapeptilida, microcistinas e ácido tumonóico nos extratos. No extrato intracelular da Fischerella sp. CENA161 identificou-se três ou quatro variantes de microcistinas, LR, LL, FR e/ou M(O)R. Fragmentos dos genes mcyA, mcyB, mcyC, mcyD, mcyE, mcyG e mcyI dessa linhagem foram seqüenciados. Nas duas análises filogenéticas realizadas com sequências de aminoácidos de McyE e sequências concatenadas de McyD, McyE e McyG, as enzimas da microcistina sintetase ficaram agrupadas de acordo com os gêneros de cianobactérias indicando um padrão de evolução / The generic affiliation of Fischerella and Hapalosiphon is problematic due to instability of morphological characters. The Fischerella and Hapalosiphon genera are differentiated by the presence of trichome multisseriate and uni or bisseriate, respectively. However, genetically these characters were not diacritical to distinguish genera. Molecular studies of strains isolated from Brazilian ecosystems are scarce for Fischerella and absent for Hapalosiphon. In this study, eight cyanobacterial strains, belonging to Hapalosiphonaceae family, isolated from Brazilian freshwater and soil were morphologically and genetically characterized and analyzed for bioactive compound productions. The morphological analyses identified five Fischerella (CENA19, CENA161, CENA212, CENA213, CENA214) and three Hapalosiphon (CENA63, CENA71, CENA72) morphotypes. The neighbor-Joining (NJ) and maximum likelihood (ML) phylogenetic analyses of 16S rRNA placed all isolated strains in high supported (99% NJ and ML of bootstrap) cluster containing members of the order Nostocales. Furthermore, the Fischerella strains studied were grouped in an internal clade with high bootstrap value (100% NJ and 86% ML), with exception of Fischerella CENA19. The position of this strain in the phylogenetic tree indicates that it needs taxonomical revision. The soil Hapalosiphon strains CENA71 and CENA72 also formed a separated tight internal clade (99% NJ and 98% ML), but the freshwater strain CENA63 was placed in a different clade (99% NJ and ML of bootstrap value) together with Hapalosiphon strains genera and Westielopsis prolifica SAG 16.93, originated from soil. The comparison of the phylogenetic analyses of individual regions of the genes 16S rRNA, rpoC1, rbcL, tufA, and cpcBA-IGS from the three Hapalosiphon strains and the two Fischerella strains CENA19 and CENA161 showed incongruent results due to different evolutionary rates of these genes. However, the concatenated phylogenetic analysis of these genes, showed that Fischerella CENA19 grouped with the two Hapalosiphon strains CENA71 and CENA72 with high bootstrap value (100%), while Fischerella CENA 161 and Hapalosiphon CENA63 were positionated each one in separate clades. The results indicate that the nomenclature of cyanobacterial strains from the family Hapalosiphonaceae needs revision. The intra and extracellular extracts of the Fischerella sp. strains CENA161 and CENA19 and Hapalosiphon sp. strains CENA71 and CENA72 showed inhibitory effects on the growth of pathogenic bacteria. The analysis in the mass spectrometer Q-TOF MS/MS indicated the presence of aeruginopeptin, cyanopeptolin, fischerellin, aeruginosin, oscillapeptilide, microcystins and tumonoic acid in the extracts. In the intracellular extracts of Fischerella sp. CENA161, three or four variants of microcystins, LR, LL, FR and/or M(O)R, were identified. Fragments of genes mcyA, mcyB, mcyC, mcyD, mcyE, mcyG and mcyI of this strain were sequenced. In both phylogenetic analyses performed with amino acid sequences of McyE and concatenated sequences of McyD, McyE and McyG, the microcystin synthetase enzymes were grouped according to the cyanobacterial genera, indicating a pattern of evolution

A afiliação genérica de Fischerella e Hapalosiphon é problemática devido à instabilidade dos caracteres morfológicos. Os gêneros Fischerella e Hapalosiphon são diferenciados pela presença de tricoma multisseriado e uni ou bisseriado, respectivamente. Porém, geneticamente esses caracteres não se mostraram diacríticos para diferenciar gêneros. Estudos moleculares de linhagens isoladas de ecossistemas brasileiros são escassos para Fischerella e inexistentes para Hapalosiphon. Neste estudo, oito linhagens de cianobactérias, pertencentes à família Hapalosiphonaceae, isoladas de água doce e solos brasileiros foram caracterizadas morfologicamente e geneticamente e analisadas para a produção de substâncias bioativas. As análises morfológicas identificaram cinco morfotípos de Fischerella (CENA19, CENA161, CENA212, CENA213, CENA214) e três de Hapalosiphon (CENA63, CENA71, CENA72). As análises filogenéticas do RNAr 16S usando neighbor-joining (NJ) e máxima verossimilhança (MV) colocaram todas as linhagens isoladas em um agrupamento com alto suporte (reamostragens de 99% NJ e MV) contendo membros da ordem Nostocales. Além disso, as linhagens de Fischerella selecionadas para o estudo agruparam-se em um clado interno com alto valor de reamostragem (100% NJ e 86% MV), com exceção da Fischerella CENA19. A posição dessa estirpe na árvore filogenética indica que necessita de revisão taxonômica. As linhagens de solo Hapalosiphon CENA71 e CENA72 também formaram um clado interno separado (99% NJ e 98% MV), mas a linhagem de água doce CENA63 foi colocada em um clado diferente (com valores de reamostragens de 99% NJ e MV), juntamente com linhagens do gênero Hapalosiphon e Westielopsis prolífica SAG 16.93, oriundas de solo. A comparação das análises filogenéticas individuais de regiões dos genes RNAr 16S, rpoC1, rbcL, tufA, e cpcBA-IGS das três linhagens de Hapalosiphon e de duas linhagens de Fischerella, CENA19 e CENA161, mostrou resultados incongruentes devido as diferentes taxas evolutivas desses genes. No entanto, a análise filogenética concatenada desses genes, mostrou que a Fischerella CENA19 agrupou com as duas linhagens de Hapalosiphon CENA71 e CENA72, com alto valor de reamostragem (100%), enquanto que a Fischerella CENA 161 e a Hapalosiphon CENA63 posicionaram-se cada uma em clados separados. Os resultados indicam que a nomenclatura das linhagens de cianobactérias da família Hapalosiphonaceae necessita de revisão. Os extratos intra e extracelulares das linhagens Fischerella sp. CENA161 e CENA19 e Hapalosiphon sp. CENA71 e CENA72 mostraram efeitos inibitórios no crescimento de bactérias patogênicas. As análises em espectrômetro de massas Q-TOF MS/MS indicaram a putativa presença de aeruginopeptina, cianopeptolina, fischerelina, aeruginosina, oscilapeptilida, microcistinas e ácido tumonóico nos extratos. No extrato intracelular da Fischerella sp. CENA161 identificou-se três ou quatro variantes de microcistinas, LR, LL, FR e/ou M(O)R. Fragmentos dos genes mcyA, mcyB, mcyC, mcyD, mcyE, mcyG e mcyI dessa linhagem foram seqüenciados. Nas duas análises filogenéticas realizadas com sequências de aminoácidos de McyE e sequências concatenadas de McyD, McyE e McyG, as enzimas da microcistina sintetase ficaram agrupadas de acordo com os gêneros de cianobactérias indicando um padrão de evolução / The generic affiliation of Fischerella and Hapalosiphon is problematic due to instability of morphological characters. The Fischerella and Hapalosiphon genera are differentiated by the presence of trichome multisseriate and uni or bisseriate, respectively. However, genetically these characters were not diacritical to distinguish genera. Molecular studies of strains isolated from Brazilian ecosystems are scarce for Fischerella and absent for Hapalosiphon. In this study, eight cyanobacterial strains, belonging to Hapalosiphonaceae family, isolated from Brazilian freshwater and soil were morphologically and genetically characterized and analyzed for bioactive compound productions. The morphological analyses identified five Fischerella (CENA19, CENA161, CENA212, CENA213, CENA214) and three Hapalosiphon (CENA63, CENA71, CENA72) morphotypes. The neighbor-Joining (NJ) and maximum likelihood (ML) phylogenetic analyses of 16S rRNA placed all isolated strains in high supported (99% NJ and ML of bootstrap) cluster containing members of the order Nostocales. Furthermore, the Fischerella strains studied were grouped in an internal clade with high bootstrap value (100% NJ and 86% ML), with exception of Fischerella CENA19. The position of this strain in the phylogenetic tree indicates that it needs taxonomical revision. The soil Hapalosiphon strains CENA71 and CENA72 also formed a separated tight internal clade (99% NJ and 98% ML), but the freshwater strain CENA63 was placed in a different clade (99% NJ and ML of bootstrap value) together with Hapalosiphon strains genera and Westielopsis prolifica SAG 16.93, originated from soil. The comparison of the phylogenetic analyses of individual regions of the genes 16S rRNA, rpoC1, rbcL, tufA, and cpcBA-IGS from the three Hapalosiphon strains and the two Fischerella strains CENA19 and CENA161 showed incongruent results due to different evolutionary rates of these genes. However, the concatenated phylogenetic analysis of these genes, showed that Fischerella CENA19 grouped with the two Hapalosiphon strains CENA71 and CENA72 with high bootstrap value (100%), while Fischerella CENA 161 and Hapalosiphon CENA63 were positionated each one in separate clades. The results indicate that the nomenclature of cyanobacterial strains from the family Hapalosiphonaceae needs revision. The intra and extracellular extracts of the Fischerella sp. strains CENA161 and CENA19 and Hapalosiphon sp. strains CENA71 and CENA72 showed inhibitory effects on the growth of pathogenic bacteria. The analysis in the mass spectrometer Q-TOF MS/MS indicated the presence of aeruginopeptin, cyanopeptolin, fischerellin, aeruginosin, oscillapeptilide, microcystins and tumonoic acid in the extracts. In the intracellular extracts of Fischerella sp. CENA161, three or four variants of microcystins, LR, LL, FR and/or M(O)R, were identified. Fragments of genes mcyA, mcyB, mcyC, mcyD, mcyE, mcyG and mcyI of this strain were sequenced. In both phylogenetic analyses performed with amino acid sequences of McyE and concatenated sequences of McyD, McyE and McyG, the microcystin synthetase enzymes were grouped according to the cyanobacterial genera, indicating a pattern of evolution

Made available in DSpace on 2017-07-10T18:13:16Z (GMT). No. of bitstreams: 1 Cesar Sary.pdf: 3688872 bytes, checksum: 62fe86e68d9974f69c34da4ecb6cfbd8 (MD5) Previous issue date: 2014-02-13 / Conselho Nacional de Desenvolvimento Científico e Tecnológico / The aim of this study was to verify the oocyte and testicular development of two species Rhamdia voulezi and Steindachneridion melanodermatum. For R. voulezi, 500 fish with four months old and average weight of 11.70 g were stocked in cages (TR) and collected monthly, for S. melanodermatum, 170 fish with four years old and average weight of 799.06 g were distributed into two cropping systems, pond (VE) and TR, and collected bimonthly. The collected animals were euthanized, weighed, measured and gonads evaluated macro and microscopically. We calculated the gonadosomatic (GSI) and hepatosomatic index, abdominal fat and condition factor &#916;K. The gonads fixed in Bouin solution were dehydrated, diaphanized and embedded in paraplast. The sections of 5&#956;m, stained by technique HE. In both species, gonads are pairs structures located dorsally in region of the abdominal cavity and fused in posterior extremity forming the oviduct and sperm duct. In R. voulezi, the ovarian development was classified in phases such as immature, development (initial, intermediate and final), capable to spawning and regression, and testicular development in phases such as immature, development, capable to release sperm and regeneration, with females in the capable spawning phase in the months from December to March, period with the highest values of IGS and &#916;K. For S. melanodermatum, females and males collected in VE showed the highest values of weight and total length on collection period (p<0.05), however it was not verified macro and microscopic difference in the ovaries and testicles of animals on VE or TR, being determined four phases for gonadal development (immature, developing, capable spawning/release sperm and regeneration). Females and males of S. melanodermatum capable to spawning were collected from October to December, period with the highest values of IGS and &#916;K. In testicle of S. melanodermatum was evidenced ovarian follicles in primary growth. / O objetivo do presente estudo foi verificar o desenvolvimento ovocitário e testicular de duas espécies, Rhamdia voulezi e Steindachneridion melanodermatum. Para R. voulezi, 500 peixes com quatro meses e peso médio de 11,70g foram estocados em tanque-rede (TR) e coletados mensalmente, para S. melanodermatum,170 peixes com quatro anos e peso médio de 799,06g foram distribuídos em dois sistemas de cultivo, viveiro escavado de terra (VE) e TR, e bimestralmente coletados. Os animais coletados foram eutanasiados, pesados, medidos e as gônadas avaliadas macro e microscópicamente. Foram calculados os índices gonadossomático (IGS), hepatossomático, gordura celomática e fator de condição &#8710;K. As gônadas fixadas em solução de Bouin foram desidratadas, diafanizadas e emblocadas em paraplast. Os cortes de 5&#956;m, corados pela técnica HE. Em ambas as espécies as gônadas são estruturas pares, localizadas dorsalmente na região da cavidade abdominal e fundidas na extremidade posterior formando o oviduto e ducto espermático. Em R. voulezi o desenvolvimento ovariano foi classificado nas fases imaturo, desenvolvimento (inicial, intermediária e final), apto a desova e regressão e desenvolvimento testicular nas fases imaturo, desenvolvimento, apto a liberar esperma e regeneração, com fêmeas em fase apta a desova nos meses de dezembro a março, período com os maiores valores do IGS e &#8710;K. Para S. melanodermatum , fêmeas e machos coletados em VE apresentaram os maiores valores de peso e comprimento total médio no período de coleta (p<0,05), no entanto não foi verificado diferença macro e microscópica nos ovários e testículos dos animais mantidos em VE ou TR, sendo determinadas quatro fases de desenvolvimento gonadal (imaturo, desenvolvimento, apto a desova/liberar esperma e regeneração). Fêmeas e machos de S. melanodermatum aptos à desova foram coletados nos meses de outubro e dezembro, período com os maiores valores do IGS e &#916;K. Em testículos de S. melanodermatum evidenciou-se a presença de folículos ovarianos em crescimento primário.

Le processus de la commutation de classe ou commutation isotypique (CSR) des gènes d’immunoglobulines caractérise les cellules de la lignée B et implique principalement les régions switch précédant les gènes constants au sein du locus IgH. Des jonctions entre la région switch donneuse Sμ et celle acceptrice Sx sont crées pendant ce processus. Plusieurs études ont démontré que le destin des cellules de la lignée B était largement modulé en fonction de la classe de l’immunoglobuline qu’elles produisent et en particulier selon les signaux transmis par leur BCR (qui peuvent par exemple pour la classe IgE, comporter des signaux pro-apoptotiques). Nous avons utilisé plusieurs modèles visant à l’étude de la physiologie et de la mécanistique du switch vers différentes classes de BCR et d’immunoglobulines peu exprimées. Nous avons cherché à forcer l’expression de l’isotype IgA2 grâce à un modèle transgénique dédié, dans le but d’approfondir les spécificités du signal BCR transduit par cet isotype en comparaison avec le BCR IgA1. En outre, et d’une façon très intéressante, nous avons découvert l’existence (jusqu’ici ignorée et masquée par les 4 autres sous-classes plus abondantes) d’une cinquième sous-classe d’IgG humaine, l’IgG5 qui est codé par un gène jusqu’ici faussement classifié pseudo-gène. Ainsi nous avons étudié les modalités d’expression du gène correspondant après un switch non-canonique,le répertoire normal des IgG5, leur représentation parmi les IgG humaines monoclonales ainsi que leurs fonctions immunitaires grâce à un IgG5 fabriquée artificiellement portant une activité anti-CD20 humaine. Enfin, nous avons testé des produits pharmaceutiques (RHPS4 : stabilisant des structures G-quadruplex au niveau d’ADN et JQ1 : inhibiteur des facteurs de transcription à bromodomaines), montrant leur capacité à retarder ou inhiber la commutation de classe in vitro mais aussi in vivo dans des souris allergiques. / The process of class switch recombination (CSR) or isotypic switching of immunoglobulin genes characterizes the B cell lineage and primarily involves switch regions preceding the constant genes within the IgH locus. Junctions between donor switch region Sμ and acceptor Sx are generated during this process. Several studies have shown that the fate of B cells is largely modulated according to the class of immunoglobulin they produce and in particular the signals transmitted by their BCR « for example for IgE, BCRs can combine proapoptotic signals. We used several relevant mouse models to study the physiological aspect and the B cell compartment after switching to IgA2 (a dedicated transgenic model expressing IgA2) since IgA2 conveys a membrane signal different from tht of IgA1. In addition, we tested two pharmaceuticals drugs(RHPS4: stabilizer of G-quadruplex structures at the DNA level and JQ1: inhibitor of bromodomain proteins) showed their ability to delay or inhibit class switching towards IgE in vitro but also in vivo in allergic mice. Interestingly, we also demonstrated the existence (till now ignored and maybe masked by the other 4 more abundant IgG subclasses) of a fifth subclass of human IgG, IgG5 which is encoded by a gene classified as a pseudo-gene. We studied the expression modalities of the corresponding gene after a non-canonical switch, the normal IgG5 repertoire, their representation among the monoclonal human IgGs as well as their immune functions through an artificially synthesited IgG5 with human anti-CD20 activity.

This thesis focuses on phylogenetic, taxonomic, ecological, and conservation aspects of the crustose lichen genus Lecania (Ramalinaceae, lichenized Ascomycota). Lecania has previously been defined on basis of relatively few morphological characters, and the genus had never been treated in molecular phylogenies. The molecular phylogeny of the genus is inferred from DNA sequences. Twenty-five species traditionally placed in Lecania are included in the study along with 21 species from closely related genera. Lecania is a polyphyletic genus. A well-supported monophyletic group containing 16 Lecania species, including the type species L. fuscella is discovered, i.e. Lecania s. str. Nine species formerly included in Lecania do not belong in the genus. A new species, L. belgica, is described. The relationships of a group of morphologically similar Lecania species, i.e. the L. cyrtella group are investigated using morphological and molecular methods. Haplotype network and phylogenetic analyses indicate that the included species, as conceived in the morphological examinations, all are monophyletic. Two new species, L. leprosa and L. madida, are described, L. proteiformis is resurrected from synonymy, and the known range of L. prasinoides is greatly expanded. The type species Lecania fuscella has become endangered in many countries. Twelve localities in Sweden where the species had been found historically are investigated, but L. fuscella is only recovered in one locality. The species composition in these 12 localities, 58 old and 5 new collections with L. fuscella is determined and analyzed. The vegetation community differs between the old and the new collections, and between the locality where the species is recovered and those where it is not. Lecania fuscella has not been able to adapt to environmental changes and now only appears in a specific type of vegetation community. The phylogenetic diversity of the species is calculated, but does not reflect the species’ evolutionary potential.

No description available.

No description available.