Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
The Liver X Receptors (LXRs) α and β and the Peroxisome Proliferator-Activated Receptor α (PPARα) are transcription factors that belong to class II nuclear receptors. They drive the expression of genes involved in hepatic lipid homeostasis and therefore are important targets for the prevention and treatment of nonalcoholic fatty liver disease (NAFLD). LXRs and PPARα are regulated by endogenous ligands, oxysterols and fatty acid derived molecules, respectively. In the liver, pharmacological activation of LXRs leads to the over-expression of genes involved in de novo lipogenesis, while PPARα is critical for fatty acid catabolism in nutrient deprivation. Even if these two nuclear receptors seemed to play opposite parts, recent studies have highlighted that PPARα also influence the expression of genes involved in fatty acids synthesis. In this study, we used pharmacological approaches and genetically engineered mice to investigate the cross-talk between LXRs and PPARα in the regulation of genes responsible for lipogenesis. We first investigated the effect of T0901317 and fenofibrate, two synthetic agonists of LXRs and PPARα, respectively. As expected, T0901317 and fenofibrate induce expression of genes involved LXR-dependent and PPARα-dependent lipogenic responses. Considering such overlapping effect, we then tested whether LXR agonist may influence PPARα driven response and vice versa. We show that the lack of PPARα does not influence the effects of T0901317 on lipogenic genes expression. However, PPARα deficiency prevents the up-regulation of genes involved in ω-hydroxylation that are induced by the LXR agonist. In addition, over-expression of lipogenic genes in response to fenofibrate is decreased in LXR knockout mice as well as the expression of PPARα target genes involved in fatty acid oxidation. Altogether, our work provides in vivo evidence for a central interconnection between nuclear receptors that drive hepatic lipid metabolism in response to oxysterol and fatty acids.
ISSN: 0300-9084

inserm-00872582
http://www.hal.inserm.fr/inserm-00872582
DOI : 10.1016/j.biochi.2012.09.028
PUBMED : 23063693

Éditeur(s) : HAL CCSD Wiley
Résumé : International audience
Bruggemann, J.H. (2016). Phylogenetic relationships within Aglaopheniidae (Cnidaria, Hydrozoa) reveal unexpected generic diversity. — Zoologica Scripta, 45, 103–114. Morphology can be misleading in the representation of phylogenetic relationships, especially in simple organisms like cnidarians and particularly in hydrozoans. These suspension feeders are widely distributed in many marine ecosystems, and the family Aglaopheniidae Marktanner-Turneretscher, 1890 is among the most diverse and visible, especially on tropical coral reefs. The taxonomy of this family is based on morphological characters with emphasis on reproductive structures for the identification of genera. This study is the most comprehensive molecular phylogeny of the Aglaopheniidae to date, including six genera and 38 species, of which 13 were investigated for the first time and sampled on tropical coral reefs throughout the Indo-Pacific region. For newly sampled individuals, we sequenced the 16S rRNA, the nuclear locus comprising the complete ITS1-5.8S rRNA gene-ITS2 and the first intron of the calmodulin nuclear gene. Phylogenetic analyses of the data revealed and confirmed a general polyphyly, or doubtful monophyly, of all sampled genera in tropical regions based on both the mitochondrial and nuclear markers. Our results revealed that several morphological characters used today are unsuited to resolve phylogenetic relationships between species and genera, as well as the high phyletic diversity within this family. Future revision of the classification of this family will require extensive geographic sampling and the use of an integrative approach.
ISSN: 0300-3256

hal-01359414
https://hal.archives-ouvertes.fr/hal-01359414
DOI : 10.1111/zsc.12135

Éditeur(s) : HAL CCSD Endocrine Society
Résumé : International audience
Transcriptional regulation by the estrogen receptor-alpha(ER) has been investigated mainly in breast cancer cell lines, but estrogens such as 17 beta-estradiol (E2) exert numerous extrareproductive effects, particularly in the liver, where E2 exhibits both protective metabolic and deleterious thrombotic actions. To analyze the direct and early transcriptional effects of estrogens in the liver, we determined the E2-sensitive transcriptome and ER cistrome in mice after acute administration of E2 or placebo. These analyses revealed the early induction of genes involved in lipid metabolism, which fits with the crucial role of ER in the prevention of liver steatosis. Characterization of the chromatin state of ER binding sites (BSs) in mice expressing or not ER demonstrated that ER is not required per se for the establishment and/or maintenance of chromatin modifications at the majority of its BSs. This is presumably a consequence of a strong overlap between ER and hepatocyte nuclear factor 4 alpha BSs. In contrast, 40% of the BSs of the pioneer factor forkhead box protein a (Foxa2) were dependent upon ER expression, and ER expression also affected the distribution of nucleosomes harboring dimethylated lysine 4 of Histone H3 around Foxa2 BSs. We finally show that, in addition to a network of liver-specific transcription factors including CCAAT/enhancer-binding protein and hepatocyte nuclear factor 4 alpha, ER might be required for proper Foxa2 function in this tissue.
ISSN: 0888-8809

hal-01357623
https://hal-univ-rennes1.archives-ouvertes.fr/hal-01357623
https://hal-univ-rennes1.archives-ouvertes.fr/hal-01357623/document
https://hal-univ-rennes1.archives-ouvertes.fr/hal-01357623/file/Changes%20in%20gene%20expression%201%20and%20Estrogen%20Receptor_accepted.pdf
DOI : 10.1210/me.2015-1311

Éditeur(s) : HAL CCSD Wiley
Résumé : International audience
BACKGROUND: Cancer/Testis (CT) genes are expressed in male gonads, repressed in most healthy somatic tissues and de-repressed in various somatic malignancies including prostate cancers (PCa). Because of their specific expression signature and their associations with tumor aggressiveness and poor outcomes, CT genes are considered to be useful biomarkers and they are also targets for the development of new anti-cancer immunotherapies. The aim of this study was to identify novel CT genes associated with hormone-sensitive prostate cancer (HSPC), and castration-resistant prostate cancer (CRPC). METHODS: To identify novel CT genes we screened genes for which transcripts were detected by RNA profiling specifically in normal testis and in either HSPC or CRPC as compared to normal prostate and 44 other healthy tissues using GeneChips. The expression and clinicopathological significance of a promising candidate-NR6A1-was examined in HSPC, CRPC, and metastatic site samples using tissue microarrays. RESULTS: We report the identification of 98 genes detected in CRPC, HSPC and testicular samples but not in the normal controls. Among them, cellular levels of NR6A1 were found to be higher in HSPC compared to normal prostate and further increased in metastatic lesions and CRPC. Furthermore, increased NR6A1 immunoreactivity was significantly associated with a high Gleason score, advanced pT stage and cancer cell proliferation. CONCLUSIONS: Our results show that cellular levels of NR6A1 are correlated with disease progression in PCa. We suggest that this essential orphan nuclear receptor is a potential therapeutic target as well as a biomarker of PCa aggressiveness. Prostate © 2013 Wiley Periodicals, Inc.
ISSN: 0270-4137

inserm-00821963
http://www.hal.inserm.fr/inserm-00821963
DOI : 10.1002/pros.22659
PUBMED : 23532770

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
Since the first molecular study of the suborder Notothenioidei in 1994, many phylogenetic studies have been published. Among these, those with a sufficient number of taxa have all suggested that the Nototheniidae, as currently defined, is monophyletic only with the inclusion of the Channichthyidae, Artedidraconidae, Bathydraconidae and Harpagiferidae. This is corroborated by more recent studies including more taxa, but in these studies either the number of nuclear markers or the number of taxa included remained low. We obtained sequences for a large sampling covering most nototheniid genera for five markers described previously for other samplings (COI, Rhodopsin retrogene, Pkd1, HECW2, and SSRP1) and one nuclear marker never used before in phylogenetic inference (PPM1d). The topology for the combined analysis of the nuclear coding genes, as well as the topology for SSRP1 (non-coding) and the combined analysis for all markers all support the paraphyly of Nototheniidae, the genus Notothenia (including Paranotothenia) is the sister group of the clade Channichthyidae, Artedidraconidae, Bathydraconidae and Harpagiferidae, and genus Gobionotothen is a sister group to both. As in previous studies, Trematomus, Lepidonotothen and Patagonotothen form a clade that also includes Indonotothenia cyanobrancha. The position of Pleuragramma antarctica, Dissostichus species and Aethotaxis mitopteryx remains unstable and dependant on markers and analyses. We therefore propose the inclusion of the four families of the High Antarctic clade in the Nototheniidae, and their transformation into subfamilies. We transfer Paranotothenia magellanica to the genus Notothenia, as Notothenia magellanica.
ISSN: 1874-7787

hal-01544914
https://hal.archives-ouvertes.fr/hal-01544914
DOI : 10.1016/j.margen.2012.02.003

Éditeur(s) : HAL CCSD Taylor & Francis
Résumé : International audience
The retroviral genome consists of an intron-containing transcript that has essential cytoplasmic functions in the infected cell. This viral transcript can escape splicing, circumvent the nuclear checkpoint mechanisms and be transported to the cytoplasm by hijacking the host machinery. Once in the cytoplasm, viral unspliced RNA acts as mRNA to be translated and as genomic RNA to be packaged into nascent viruses. The murine leukemia virus (MLV) is among the first retroviruses discovered and is classified as simple Retroviridae due to its minimal encoding capacity. The oncogenic and transduction abilities of MLV are extensively studied, whereas surprisingly the crucial step of its nuclear export has remained unsolved until 2014. Recent work has revealed the recruitment by MLV of the cellular NXF1/Tap-dependent pathway for export. Unconventionally, MLV uses of Tap to export both spliced and unspliced viral RNAs. Unlike other retroviruses, MLV does not harbor a unique RNA signal for export. Indeed, multiple sequences throughout the MLV genome appear to promote export of the unspliced MLV RNA. We review here the current understanding of the export mechanism and highlight the determinants that influence MLV export. As the molecular mechanism of MLV export is elucidated, we will gain insight into the contribution of the export pathway to the cytoplasmic fate of the viral RNA
ISSN: 1547-6286

hal-01217990
https://hal-univ-rennes1.archives-ouvertes.fr/hal-01217990
https://hal-univ-rennes1.archives-ouvertes.fr/hal-01217990/document
https://hal-univ-rennes1.archives-ouvertes.fr/hal-01217990/file/Insights%20into%20the%20nuclear%20export%20of%20murine%20leukemia%20virus%20intron-containing%20RNA.pdf
DOI : 10.1080/15476286.2015.1065375

Éditeur(s) : Public Library Science
Résumé : Background: Reconstructing the history of divergence and gene flow between closely-related organisms has long been a difficult task of evolutionary genetics. Recently, new approaches based on the coalescence theory have been developed to test the existence of gene flow during the process of divergence. The deep sea is a motivating place to apply these new approaches. Differentiation by adaptation can be driven by the heterogeneity of the hydrothermal environment while populations should not have been strongly perturbed by climatic oscillations, the main cause of geographic isolation at the surface. Methodology/Principal Finding: Samples of DNA sequences were obtained for seven nuclear loci and a mitochondrial locus in order to conduct a multi-locus analysis of divergence and gene flow between two closely related and hybridizing species of hydrothermal vent mussels, Bathymodiolus azoricus and B. puteoserpentis. The analysis revealed that (i) the two species have started to diverge approximately 0.760 million years ago, (ii) the B. azoricus population size was 2 to 5 time greater than the B. puteoserpentis and the ancestral population and (iii) gene flow between the two species occurred over the complete species range and was mainly asymmetric, at least for the chromosomal regions studied. Conclusions/Significance: A long history of gene flow has been detected between the two Bathymodiolus species. However, it proved very difficult to conclusively distinguish secondary introgression from ongoing parapatric differentiation. As powerful as coalescence approaches could be, we are left by the fact that natural populations often deviates from standard assumptions of the underlying model. A more direct observation of the history of recombination at one of the seven loci studied suggests an initial period of allopatric differentiation during which recombination was blocked between lineages. Even in the deep sea, geographic isolation may well be a crucial promoter of speciation.
Plos One (1932-6203) (Public Library Science), 2009-08 , Vol. 4 , N. 8 , P. 1-15

Droits : 2009 Faure et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
http://archimer.ifremer.fr/doc/00129/24012/21972.pdf
DOI:10.1371/journal.pone.0006485
http://archimer.ifremer.fr/doc/00129/24012/

Éditeur(s) : HAL CCSD
Résumé :  Diffusion du document : INRA Antilles-Guyane, UMR ECOFOG, F97387 Kourou, Guyane (France)Diplôme : Master Recherche
il s'agit d'un type de produit dont les métadonnées ne correspondent pas aux métadonnées attendues dans les autres types de produit : DISSERTATION
Origin and maintenance of species diversity is one of the main questions in evolutive biology. Species complexes, ie sister species still exchanging genes, are common in tropical forests and contribute to this diversity. This poster describes the organization of the genetic diversity in two closely related tree species, Carapa guianensis and C. procera, which are in sympatry in French Guiana. By using a clustering method based on nuclear markers (Pritchard et al. 2000), 506 trees sampled in French Guiana have been assigned to a species. Interestingly, many individuals harbored intermediate genome and we assigned to an hybrid group. The geographic distribution of these individuals revealed the presence of a contact zone between the two carapa species in the Eastern part of French Guiana. We then analysed genetic diversity at cholroplast genome and revealed a symmetrical gene flow between the two sister species. In addition, hybridization between hybrids and parental species ar likely possible but still need validations thanks to control crosses. Within species, we finally revealed the presence of a departure from the neutral equilibrium in thedirection of a population expansion likely related to Holocene perturbations. This expansion may have contributed to the hybrid zone formation in French Guiana.
L'origine et le maintien de la diversité spécifique des forêts tropicales humides est une question clé en biologie évolutive. Ce travail contribue à améliorer la compréhension de ces mécanismes à travers l'étude de la distribution de la diversité génétique de deux espèces sœurs interfertiles, le Carapa procera et C. guianensis en Guyane. L'assignation botanique des arbres échantillonnés (506) a été effectuée en adoptant une approche moléculaire qui repose sur l'analyse de la répartition des fréquences alléliques de six microsatellites nucléaires (Pritchard et al. 2000). Chaque locus présente des allèles dont les différences de fréquences entre espèces sont importantes, permettant ainsi d'envisager des outils simples de reconnaissances pour ces espèces difficilement identifiables sur la seule base de leurs caractères phénotypiques. Une zone de contact des deux espèces où les phénomènes d'hybridations sont fréquents a par ailleurs été localisée. En associant une analyse de la diversité au niveau du génome chloroplastique sur un sous ensemble d'individus (244), j'ai pu montrer que l'introgression est bidirectionnelle et que les backcross sont possibles. Les flux de gènes entre les deux espèces sont fréquents, et à l'intérieur des espèces, les populations sont peu structurées bien que la différenciation soit significative entre les sites les plus éloignés. Enfin, ce travail met en évidence que les populations de chacune des deux espèces présentent un signal d'expansion de population, avec un signal plus fort pour le C. procera, qui laisse présager une expansion récente, vraisemblablement à l'origine de la zone de contact. L'impact des évènements climatiques et/ou des activités amérindiennes des 10 000 dernières années pourrait expliquer la restriction puis l'expansion de ce genre post pionnier.
https://hal.archives-ouvertes.fr/hal-01189488

hal-01189488
https://hal.archives-ouvertes.fr/hal-01189488
PRODINRA : 42333

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
The transcription factor nuclear factor-erythroid 2-related-2 (Nrf2) controls cellular redox homeostasis and displays immunomodulatory properties. Nrf2 alters cytokine expression in murine T cells, but its effects in human T lymphocytes are unknown. This study investigated the expression and activity of Nrf2 in human activated CD4(+) T helper lymphocytes (Th cells) that mediate the adaptive immune response. Th cells were isolated from peripheral blood mononuclear cells and activated with antibodies against CD3 and CD28, mimicking physiologic Th cell stimulation by dendritic cells. Nrf2 is hardly detectable in unstimulated Th cells. Activation of Th cells rapidly and strongly increases the levels of Nrf2 protein by increasing NRF2 gene transcription. Th cell activation also enhances mRNA and protein levels of Nrf2 target genes encoding antioxidant enzymes. Blocking Nrf2 expression using chemical inhibitors or siRNAs prevents these gene inductions. Pretreatment with inorganic arsenic, a Nrf2 inducer that does not alter NRF2 gene expression, increases protein level and transcriptional activity of Nrf2 induced by Th cell stimulation. Inorganic arsenic enhances nuclear translocation of Nrf2, its interaction with the coactivator protein p300, and its DNA binding activity. Inhibition of Nrf2 expression abrogates the effects of inorganic arsenic on mRNA levels of antioxidant genes, but does not alter the expression of IL-2, TNF-α, interferon-γ, or IL-17 in Th cells activated in the absence or presence of the metalloid. In conclusion, this study demonstrates for the first time that stimulation of human Th cells increases transcription of the NRF2 gene and activity of the Nrf2 protein. However, modulation of Nrf2 levels does not modify the secretion of inflammatory cytokines from these T lymphocytes.
ISSN: 0891-5849

hal-01018643
https://hal-univ-rennes1.archives-ouvertes.fr/hal-01018643
https://hal-univ-rennes1.archives-ouvertes.fr/hal-01018643/document
https://hal-univ-rennes1.archives-ouvertes.fr/hal-01018643/file/Nrf2_expression_and_activity_in_human_T_lymphocytes_accepted.pdf
DOI : 10.1016/j.freeradbiomed.2014.03.006

Éditeur(s) : HAL CCSD
Résumé : International audience
Estrogen receptor alpha (ERα) has been recognized now for several decades as playing a key role in reproduction and exerting functions in numerous nonreproductive tissues. In this review, we attempt to summarize the in vitro studies that are the basis of our current understanding of the mechanisms of action of ERα as a nuclear receptor and the key roles played by its two activation functions (AFs) in its transcriptional activities. We then depict the consequences of the selective inactivation of these AFs in mouse models, focusing on the prominent roles played by ERα in the reproductive tract and in the vascular system. Evidence has accumulated over the two last decades that ERα is also associated with the plasma membrane and activates non-nuclear signaling from this site. These rapid/nongenomic/membrane-initiated steroid signals (MISS) have been characterized in a variety of cell lines, and in particular in endothelial cells. The development of selective pharmacological tools that specifically activate MISS and the generation of mice expressing an ERα protein impeded for membrane localization have begun to unravel the physiological role of MISS in vivo. Finally, we discuss novel perspectives for the design of tissue-selective ER modulators based on the integration of the physiological and pathophysiological roles of MISS actions of estrogens.
Physiological Reviews

hal-01533249
https://hal-univ-rennes1.archives-ouvertes.fr/hal-01533249
DOI : 10.1152/physrev.00024.2016
PUBMED : 28539435

Éditeur(s) : HAL CCSD MDPI
Résumé : International audience
In mammals, the effects of estrogen are mainly mediated by two different estrogen receptors, ERα and ERβ. These proteins are members of the nuclear receptor family, characterized by distinct structural and functional domains, and participate in the regulation of different biological processes, including cell growth, survival and differentiation. The two estrogen receptor (ER) subtypes are generated from two distinct genes and have partially distinct expression patterns. Their activities are modulated differently by a range of natural and synthetic ligands. Some of these ligands show agonistic or antagonistic effects depending on ER subtype and are described as selective ER modulators (SERMs). Accordingly, a few phytochemicals, called phytoestrogens, which are synthesized from plants and vegetables, show low estrogenic activity or anti-estrogenic activity with potentially anti-proliferative effects that offer nutraceutical or pharmacological advantages. These compounds may be used as hormonal substitutes or as complements in breast cancer treatments. In this review, we discuss and summarize the in vitro and in vivo effects of certain phytoestrogens and their potential roles in the interaction with estrogen receptors.
ISSN: 1422-0067

hal-01560283
https://hal-univ-rennes1.archives-ouvertes.fr/hal-01560283
PUBMED : 28657580
DOI : 10.3390/ijms18071381

Éditeur(s) : HAL CCSD Wiley
Résumé : [b]Aim[/b][br/] Many tropical tree species have poorly delimited taxonomic boundaries and contain undescribed or cryptic species. We examined the genetic structure of a species complex in the tree genus Carapa in the Neotropics in order to evaluate age, geographic patterns of diversity and evolutionary relationships, and to quantify levels of introgression among currently recognized species.[br/] [br/] [b]Location[/b][br/] Lowland moist forests in the Guiana Shield, the Central and Western Amazon Basin, Chocó and Central America.[br/] [br/] [b]Methods[/b][br/] Genetic structure was analysed using seven nuclear simple sequence repeats (nuSSR), five chloroplast SSRs (cpSSR), and two chloroplast DNA (cpDNA) intergenic sequences (trnH-psbA and trnC-ycf6). Bayesian clustering analysis of the SSR data was used to infer population genetic structure and to assign 324 samples to their most likely genetic cluster. Bayesian coalescence analyses were performed on the two cpDNA markers to estimate evolutionary relationships and divergence times.[br/] [br/] [b]Results[/b][br/] Two genetic clusters (nu_guianensis and nu_surinamensis) were detected, which correspond to the Neotropical species C. guianensis (sensu latu) and C. surinamensis. Fourteen cpDNA haplotypes clustered into six haplogroups distributed between the two nuclear genetic clusters. Divergence between the haplogroups was initiated in the Miocene, with some haplotype structure evolving as recently as the Pleistocene. The absence of complete lineage sorting between the nuclear and chloroplast genomes and the presence of hybrid individuals suggest that interspecific reproductive barriers are incomplete. NuSSR diversity was highest in C. guianensis and, within C. guianensis, cpDNA diversity was highest in the Central and Western Amazon Basin. Regional genetic differentiation was strong but did not conform to an isolation-by-distance process or exhibit a phylogeographical signal.[br/] [br/] [b]Main conclusions[/b][br/] The biogeographical history of Neotropical Carapa appears to have been influenced by events that took place during the Neogene. Our results point to an Amazonian centre of origin and diversification of Neotropical Carapa, with subsequent migration to the Pacific coast of South America and Central America. Gene flow apparently occurs among species, and introgression events are supported by inconsistencies between chloroplast and nuclear lineage sorting. The absence of phylogeographical structure may be a result of the ineffectiveness of geographical barriers among populations and of reproductive isolation mechanisms among incipient and cryptic species in this species complex.
ISSN: 0305-0270

hal-01032395
https://hal.archives-ouvertes.fr/hal-01032395
DOI : 10.1111/j.1365-2699.2011.02678.x

Éditeur(s) : HAL CCSD Springer Verlag
Résumé : We aimed to enhance understanding of the molecular diversity of arbuscular mycorrhizal fungi (AMF) by building a new global dataset targeting previously unstudied geographical areas. In total, we sampled 96 plant species from 25 sites that encompassed all continents except Antarctica. AMF in plant roots were detected by sequencing the nuclear SSU rRNA gene fragment using either cloning followed by Sanger sequencing or 454-sequencing. A total of 204 AMF phylogroups (virtual taxa, VT) were recorded, increasing the described number of Glomeromycota VT from 308 to 341 globally. Novel VT were detected from 21 sites; three novel but nevertheless widespread VT (Glomus spp. MO-G52, MO-G53, MO-G57) were recorded from six continents. The largest increases in regional VT number were recorded in previously little-studied Oceania and in the boreal and polar climatic zones - this study providing the first molecular data from the latter. Ordination revealed differences in AM fungal communities between different continents and climatic zones, suggesting that both biogeographic history and environmental conditions underlie the global variation of those communities. Our results show that a considerable proportion of Glomeromycota diversity has been recorded in many regions, though further large increases in richness can be expected in remaining unstudied areas.
ISSN: 0940-6360

hal-01190520
https://hal.archives-ouvertes.fr/hal-01190520
DOI : 10.1007/s00572-013-0482-2
PRODINRA : 206968

Éditeur(s) : HAL CCSD BioMed Central
Résumé : International audience
Background: The Hippo pathway regulates growth rate and organ size in fly and mouse, notably through control of cell proliferation. Molecular interactions at the heart of this pathway are known to have originated in the unicellular ancestry of metazoans. They notably involve a cascade of phosphorylations triggered by the kinase Hippo, with sub‑ sequent nuclear to cytoplasmic shift of Yorkie localisation, preventing its binding to the transcription factor Scalloped, thereby silencing proliferation genes. There are few comparative expression data of Hippo pathway genes in non‑ model animal species and notably none in non‑bilaterian phyla.Results: All core Hippo pathway genes could be retrieved from the ctenophore Pleurobrachia pileus and the hydro‑ zoan cnidarian Clytia hemisphaerica, with the important exception of Yorkie in ctenophore. Expression study of the Hippo, Salvador and Scalloped genes in tentacle " cellular conveyor belts " of these two organisms revealed striking differences. In P. pileus, their transcripts were detected in areas where undifferentiated progenitors intensely prolifer‑ ate and where expression of cyclins B and D was also seen. In C. hemisphaerica, these three genes and Yorkie are expressed not only in the proliferating but also in the differentiation zone of the tentacle bulb and in mature tentacle cells. However, using an antibody designed against the C. hemiphaerica Yorkie protein, we show in two distinct cell lineages of the medusa that Yorkie localisation is predominantly nuclear in areas of active cell proliferation and mainly cytoplasmic elsewhere.Conclusions: This is the first evidence of nucleocytoplasmic Yorkie shift in association with the arrest of cell prolifera‑ tion in a cnidarian, strongly evoking the cell division‑promoting role of this protein and its inhibition by the activated Hippo pathway in bilaterian models. Our results furthermore highlight important differences in terms of deployment and regulation of Hippo pathway genes between cnidarians and ctenophores.
ISSN: 2041-9139

Droits : http://creativecommons.org/licenses/by/
hal-01286578
http://hal.upmc.fr/hal-01286578
http://hal.upmc.fr/hal-01286578/document
http://hal.upmc.fr/hal-01286578/file/comparative.pdf
DOI : 10.1186/s13227-016-0041-y

Éditeur(s) : HAL CCSD National Academy of Sciences
Résumé : International audience
The integration of foreign genetic information is central to the evolution of eukaryotes, as has been demonstrated for the origin of the Calvin cycle and of the heme and carotenoid biosynthesis pathways in algae and plants. For photosynthetic lineages, this coordination involved three genomes of divergent phylogenetic origins (the nucleus, plastid, and mitochondrion). Major hurdles overcome by the ancestor of these lineages were harnessing the oxygen-evolving organelle, optimizing the use of light, and stabilizing the partnership between the plastid endosymbiont and host through retargeting of proteins to the nascent organelle. Here we used protein similarity networks that can disentangle reticulate gene histories to explore how these significant challenges were met. We discovered a previously hidden component of algal and plant nuclear genomes that originated from the plastid endosymbiont: symbiogenetic genes (S genes). These composite proteins, exclusive to photosynthetic eukaryotes, encode a cyanobacterium-derived domain fused to one of cyanobacterial or another prokaryotic origin and have emerged multiple, independent times during evolution. Transcriptome data demonstrate the existence and expression of S genes across a wide swath of algae and plants, and functional data indicate their involvement in tolerance to oxidative stress, phototropism, and adaptation to nitrogen limitation. Our research demonstrates the ``recycling'' of genetic information by photosynthetic eukaryotes to generate novel composite genes, many of which function in plastid maintenance.
ISSN: 0027-8424

hal-01544793
https://hal.archives-ouvertes.fr/hal-01544793
DOI : 10.1073/pnas.1517551113

Éditeur(s) : Wiley-blackwell
Résumé : A new benthic dinoflagellate species, Prorocentrum bimaculatum sp. nov., is studied from Kuwaits marine sediments, based on detailed morphological and molecular data. Cells are large, oblong oval in shape. They are 49.955.3 mu m long and 38.443.2 mu m wide. The ornamentation of this new species is peculiar, and characterized by smooth valves with large pores (0.320.50 mu m) scattered on their surface, except in two circular patches of similar to 15 mu m in diameter, devoid of ornamentation and located on both sides of the valve centers. The periflagellar area is widely triangular, located in a moderate excavation of the right valve, and comprises nine platelets. The intercalary band of P. bimaculatum is smooth. The molecular phylogenetic position of this new taxon was inferred from SSU and LSU rDNA genes. In both phylogenetic analyses, P. bimaculatum branched with high support with Prorocentrum consutum and formed a clade sister to the one including P. lima and related species such as P. arenarium, P. belizeanum, P. hoffmannianum, and P. maculosum. From the phylogenetic study, since most species related to P. bimaculatum are known for their toxic effects and production of okadaic acid, this new species can be considered as a potential toxin producer, but this has to be analyzed.
Journal Of Phycology (0022-3646) (Wiley-blackwell), 2012-02 , Vol. 48 , N. 1 , P. 211-221

Droits : 2012 Phycological Society of America
http://archimer.ifremer.fr/doc/00066/17756/15698.pdf
DOI:10.1111/j.1529-8817.2011.01102.x
http://archimer.ifremer.fr/doc/00066/17756/

Éditeur(s) : HAL CCSD Wiley
Résumé : International audience
Morphology can be misleading in the representation of phylogenetic relationships, especially in simple organisms like cnidarians and particularly in hydrozoans. These suspension feeders are widely distributed in many marine ecosystems, and the family Aglaopheniidae Marktanner-Turneretscher, 1890 is among the most diverse and visible, especially on tropical coral reefs. The taxonomy of this family is based on morphological characters with emphasis on reproductive structures for the identification of genera. This study is the most comprehensive molecular phylogeny of the Aglaopheniidae to date, including six genera and 38 species, of which 13 were investigated for the first time and sampled on tropical coral reefs throughout the Indo-Pacific region. For newly sampled individuals, we sequenced the 16S rRNA, the nuclear locus comprising the complete ITS1-5.8S rRNA gene-ITS2 and the first intron of the calmodulin nuclear gene. Phylogenetic analyses of the data revealed and confirmed a general polyphyly, or doubtful monophyly, of all sampled genera in tropical regions based on both the mitochondrial and nuclear markers. Our results revealed that several morphological characters used today are unsuited to resolve phylogenetic relationships between species and genera, as well as the high phyletic diversity within this family. Future revision of the classification of this family will require extensive geographic sampling and the use of an integrative approach.
ISSN: 0300-3256

hal-01253738
https://hal.archives-ouvertes.fr/hal-01253738
https://hal.archives-ouvertes.fr/hal-01253738/document
https://hal.archives-ouvertes.fr/hal-01253738/file/Phylogenetic%20relationships%20within%20Aglaopheniidae%20%28Cnidaria%2C._hal.pdf
DOI : 10.1111/zsc.12135

Éditeur(s) : Oxford Univ Press
Résumé : The interrogation of genetic markers in environmental meta-barcoding studies is currently seriously hindered by the lack of taxonomically curated reference data sets for the targeted genes. The Protist Ribosomal Reference database (PR2, http://ssurrna. org/) provides a unique access to eukaryotic small sub-unit (SSU) ribosomal RNA and DNA sequences, with curated taxonomy. The database mainly consists of nuclear-encoded protistan sequences. However, metazoans, land plants, macrosporic fungi and eukaryotic organelles (mitochondrion, plastid and others) are also included because they are useful for the analysis of hightroughput sequencing data sets. Introns and putative chimeric sequences have been also carefully checked. Taxonomic assignation of sequences consists of eight unique taxonomic fields. In total, 136 866 sequences are nuclear encoded, 45 708 (36 501 mitochondrial and 9657 chloroplastic) are from organelles, the remaining being putative chimeric sequences. The website allows the users to download sequences from the entire and partial databases (including representative sequences after clustering at a given level of similarity). Different web tools also allow searches by sequence similarity. The presence of both rRNA and rDNA sequences, taking into account introns (crucial for eukaryotic sequences), a normalized eight terms ranked-taxonomy and updates of new GenBank releases were made possible by a long-term collaboration between experts in taxonomy and computer scientists.
Nucleic Acids Research (0305-1048) (Oxford Univ Press), 2013-01 , Vol. 41 , N. D1 , P. D597-D604

Droits : The Author(s) 2012. Published by Oxford University Press.
http://archimer.ifremer.fr/doc/00114/22492/20174.pdf
DOI:10.1093/nar/gks1160
http://archimer.ifremer.fr/doc/00114/22492/

Éditeur(s) : HAL CCSD Publisher : Baltimore : Williams & Wilkins, c1950-. Latest Publisher : Bethesda, MD : American Association of Immunologists
Résumé : International audience
Schistosome infection is a major public health concern affecting millions of people living in tropical regions of Africa, Asia, and South America. Schistosomes cause mild clinical symptoms in most subjects, whereas a small proportion of individuals presents severe clinical disease (as periportal fibrosis (PPF)) that may lead to death. Severe PPF results from an abnormal deposition of extracellular matrix proteins in the periportal spaces due to a chronic inflammation triggered by eggs and schistosome Ags. Extracellular matrix protein production is regulated by a number of cytokines, including IFN-gamma. We have now screened putative polymorphic sites within this gene in a population living in an endemic area for Schistosoma mansoni. Two polymorphisms located in the third intron of the IFN-gamma gene are associated with PPF. The IFN-gamma +2109 A/G polymorphism is associated with a higher risk for developing PPF, whereas the IFN-gamma +3810 G/A polymorphism is associated with less PPF. The polymorphisms result in changes in nuclear protein interactions with the intronic regions of the gene, suggesting that they may modify IFN-gamma mRNA expression. These results are consistent with the results of previous studies. Indeed, PPF is controlled by a major locus located on chromosome 6q22-q23, closely linked to the gene encoding the alpha-chain of the IFN-gamma receptor, and low IFN-gamma producers have been shown to have an increased risk of severe PPF. Together, these observations support the view that IFN-gamma expression and subsequent signal transduction play a critical role in the control of PPF in human hepatic schistosome infection (S. mansoni).
ISSN: 0022-1767

Droits : http://creativecommons.org/licenses/by-nc-nd/
hal-01211760
https://hal.archives-ouvertes.fr/hal-01211760
https://hal.archives-ouvertes.fr/hal-01211760/document
https://hal.archives-ouvertes.fr/hal-01211760/file/J%20Immunol-2003-Chevillard-5596-601.pdf
DOI : 10.4049/jimmunol.171.10.5596

Éditeur(s) : HAL CCSD Endocrine Society
Résumé : International audience
Sertoli cells (SCs), the only somatic cells within seminiferous tubules, associate intimately with developing germ cells. They not only provide physical and nutritional support but also secrete factors essential to the complex developmental processes of germ cell proliferation and differentiation. The SC transcriptome must therefore adapt rapidly during the different stages of spermatogenesis. We report comprehensive genome-wide expression profiles of pure populations of SCs isolated at 5 distinct stages of the first wave of mouse spermatogenesis, using RNA sequencing technology. We were able to reconstruct about 13 901 high-confidence, nonredundant coding and noncoding transcripts, characterized by complex alternative splicing patterns with more than 45% comprising novel isoforms of known genes. Interestingly, roughly one-fifth (2939) of these genes exhibited a dynamic expression profile reflecting the evolving role of SCs during the progression of spermatogenesis, with stage-specific expression of genes involved in biological processes such as cell cycle regulation, metabolism and energy production, retinoic acid synthesis, and blood-testis barrier biogenesis. Finally, regulatory network analysis identified the transcription factors endothelial PAS domain-containing protein 1 (EPAS1/Hif2α), aryl hydrocarbon receptor nuclear translocator (ARNT/Hif1β), and signal transducer and activator of transcription 1 (STAT1) as potential master regulators driving the SC transcriptional program. Our results highlight the plastic transcriptional landscape of SCs during the progression of spermatogenesis and provide valuable resources to better understand SC function and spermatogenesis and its related disorders, such as male infertility.
ISSN: 0888-8809

hal-01146846
https://hal-univ-rennes1.archives-ouvertes.fr/hal-01146846
DOI : 10.1210/me.2014-1356
PUBMED : 25710594