Éditeur(s) : HAL CCSD Wiley
Résumé : International audience
The shallow-water bivalve Codakia orbiculata which harbors gill-endosymbiotic sulfur-oxidizing ?-proteobacteria can lose and acquire its endosymbionts throughout its life. Long-term starvation and recolonization experiments led to changes in the organization of cells in the lateral zone of gill filaments. This plasticity is linked to the presence or absence of gill-endosymbionts. Herein, we propose that this reorganization can be explained by three hypotheses: (a) a variation in the number of bacteriocytes and granule cells due to proliferation or apoptosis processes, (b) a variation of the volume of these two cell types without modification in the number, and (c) a combination of both number and cell volume variation. To test these hypotheses, we analyzed cell reorganization in terms of proliferation and apoptosis in adults submitted to starvation and returned to the field using catalyzed reporter deposition fluorescence in situ hybridization, immunohistochemistry, and structural analyses. We observed that cell and tissue reorganization in gills filaments is due to a variation in cell relative abundance that maybe associated with a variation in cell apparent volume and depends on the environment. In fact, bacteriocytes mostly multiply in freshly collected and newly recolonized individuals, and excess bacteriocytes are eliminated in later recolonization stages. We highlight that host tissue regeneration in gill filaments of this symbiotic bivalve can occur by both replication of existing cells and division of undifferentiated cells localized in tissular bridges, which might be a tissue-specific multipotent stem cell zone.
ISSN: 1059-910X

hal-01545915
https://hal.archives-ouvertes.fr/hal-01545915
DOI : 10.1002/jemt.22041

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
https://hal.archives-ouvertes.fr/hal-01664245

Droits : http://creativecommons.org/licenses/by-nc-nd/
hal-01664245
https://hal.archives-ouvertes.fr/hal-01664245
https://hal.archives-ouvertes.fr/hal-01664245/document
https://hal.archives-ouvertes.fr/hal-01664245/file/L%27AUTRE%20SCENE_L%27ESPACE%20DU%20REVE%20DANS%20DREAM%20ON%20MONKEY%20MOUNTAIN%20DE%20DEREK%20WALCOTT.pdf

Éditeur(s) : HAL CCSD Hindawi Publishing Corporation
Résumé : International audience
Two genes, that is, 5S ribosomal sequences and antifreeze glycoprotein (AFGP) genes, were mapped onto chromosomes of eight Antarctic notothenioid fish possessing a X1X1X2X2/X1X2Y sex chromosome system, namely, Chionodraco hamatus and Pagetopsis macropterus (family Channichthyidae), Trematomus hansoni, T. newnesi, T. nicolai, T. lepidorhinus, and Pagothenia borchgrevinki (family Nototheniidae), and Artedidraco skottsbergi (family Artedidraconidae). Through fluorescence in situ hybridization (FISH), we uncovered distinct differences in the gene content of the Y chromosomes in the eight species, with C. hamatus and P. macropterus standing out among others in bearing 5S rDNA and AFGP sequences on their Y chromosomes, respectively. Both genes were absent from the Y chromosomes of any analyzed species. The distinct patterns of Y and non-Y chromosome association of the 5S rDNA and AFGP genes in species representing different Antarctic fish families support an independent origin of the sex heterochromosomes in notothenioids with interesting implications for the evolutionary/adaptational history of these fishes living in a cold-stable environment.
ISSN: 2314-6133

hal-01544911
https://hal.archives-ouvertes.fr/hal-01544911
DOI : 10.1155/2013/243938

Éditeur(s) : HAL CCSD Public Library of Science
Résumé : International audience
Vertebrate genomes contain around 20,000 protein-encoding genes, of which a large fraction is still not associated with specific functions. A major task in future genomics will thus be to assign physiological roles to all open reading frames revealed by genome sequencing. Here we show that C2orf62, a highly conserved protein with little homology to characterized proteins, is strongly expressed in testis in zebrafish and mammals, and in various types of ciliated cells during zebrafish development. By yeast two hybrid and GST pull-down, C2orf62 was shown to interact with TTC17, another uncharacterized protein. Depletion of either C2orf62 or TTC17 in human ciliated cells interferes with actin polymerization and reduces the number of primary cilia without changing their length. Zebrafish embryos injected with morpholinos against C2orf62 or TTC17, or with mRNA coding for the C2orf62 C-terminal part containing a RII dimerization/docking (R2D2) - like domain show morphological defects consistent with imperfect ciliogenesis. We provide here the first evidence for a C2orf62-TTC17 axis that would regulate actin polymerization and ciliogenesis.
ISSN: 1932-6203

hal-00955242
https://hal-univ-rennes1.archives-ouvertes.fr/hal-00955242
https://hal-univ-rennes1.archives-ouvertes.fr/hal-00955242/document
https://hal-univ-rennes1.archives-ouvertes.fr/hal-00955242/file/C2orf62_and_TTC17-accepted.pdf
DOI : 10.1371/journal.pone.0086476

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
The separation of the germ line from the soma is a classic concept in animal biology, and depending on species is thought to involve fate determination either by maternally localized germ plasm (''preformation'' or ``maternal inheritance'') or by inductive signaling (classically termed ``epigenesis'' or ``zygotic induction''). The latter mechanism is generally considered to operate in non-bilaterian organisms such as cnidarians and sponges, in which germ cell fate is determined at adult stages from multipotent stem cells. We have found in the hydrozoan cnidarian Clytia hemisphaerica that the multipotent ``interstitial'' cells (i-cells) in larvae and adult medusae, from which germ cells derive, express a set of conserved germ cell markers: Vasa, Nanos1, Piwi and PL10. In situ hybridization analyses unexpectedly revealed maternal mRNAs for all these genes highly concentrated in a germ plasm-like region at the egg animal pole and inherited by the i-cell lineage, strongly suggesting i-cell fate determination by inheritance of animal-localized factors. On the other hand, experimental tests showed that i-cells can form by epigenetic mechanisms in Clytia, since larvae derived from both animal and vegetal blastomeres separated during cleavage stages developed equivalent i-cell populations. Thus Clytia embryos appear to have maternal germ plasm inherited by i-cells but also the potential to form these cells by zygotic induction. Reassessment of available data indicates that maternally localized germ plasm molecular components were plausibly present in the common cnidarian/bilaterian ancestor, but that their role may not have been strictly deterministic.
ISSN: 0012-1606

hal-01544487
https://hal.archives-ouvertes.fr/hal-01544487
DOI : 10.1016/j.ydbio.2012.01.018

Éditeur(s) : HAL CCSD Springer Verlag (Germany)
Résumé : International audience
A hybrid linear ion-trap Fourier-transform ion cyclotron resonance mass spectrometer was used for top-down characterization of the abundant human salivary Cystatins, including S, S1, S2, SA, SN, C, and D, using collisionally activated dissociation (CAD) after chromatographic purification of the native, disulfide intact proteins from saliva. Post-translational modifications and protein sequence polymorphisms arising from single nucleotide polymorphisms (SNPs) were assigned from precursor and product ion masses at a tolerance of 10 ppm allowing confident identification of individual intact mass tags. Cystatins S, S1, S2, SA and SN were cleaved of a N-terminal 20 amino-acid signal peptide, and Cystatin C a 26-residue peptide, to yield a generally conserved N-terminus. In contrast, Cystatin D isoforms with 24 and 28 amino-acid residue N-terminal truncations were found such that their N-termini were not conserved. Cystatin S1 was phosphorylated at Ser3, while S2 was phosphorylated at Ser1 and Ser3 of the mature protein, in agreement with previous work. Both Cystatin D isoforms carried the polymorphism C46R (SNP: rs1799841). The 14328 Da isoform of Cystatin SN previously assigned with polymorphism P31L due to a SNP (rs2070856) was found only in whole saliva. Parotid secretions contained no detectable Cystatins while whole saliva largely mirrored the contents of submandibular/sublingual (SMSL) secretions. Top-down high-resolution mass spectrometry is a powerful tool for the identification and characterization of potential protein biomarkers in saliva.
ISSN: 1044-0305

hal-00677483
https://hal.archives-ouvertes.fr/hal-00677483
DOI : 10.1016/j.jasms.2010.01.025

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
The identification of a large OIB-type volcanic sequence on top of an obducted nappe in the Lesser Caucaus of Armenia helps us explain the obduction processes in the Caucasus region that are related to dramatic change in the global tectonics of the Tethyan region in the late Lower Cretaceous. The ophiolitic nappe preserves three distinct magmatic series, obducted in a single tectonic slice over the South Armenian Block during the Coniacian-Santonian (88-83 Ma), the same time as the Oman ophiolite. Similar geological, petrological, geochemical and age features for various Armenian ophiolitic massifs (Sevan, Stepanavan, and Vedi) argue for the presence of a single large obducted ophiolite unit. The ophiolite, shows evidence for a slow-spreading oceanic environment in Lower to Middle Jurassic. Serpentinites, gabbros and plagiogranites were exhumed by normal faults, and covered by radiolarites. Few pillow-lava flows have infilled the rift grabens. The ophiolite lavas have hybrid geochemical composition intermediate between Arc and MORB signatures: (La/Yb)(N) = 0.6-0.9: (Nb/Th)(N) = 0.17-0.57; (Nd-143/Nd-144)(i) = 0.51273-0.51291; (Sr-87/Sr-86)(i) = 0.70370-0.70565; (Pb-207/Pb-204)(i) = 15.4587-15.5411; (Pb-208/Pb-204)(i) = 37.4053-38.2336; (Pb-206/Pb-204)(i) = 17.9195-18.4594. These compositions suggest they were probably formed in a back-arc basin by melting of a shallow asthenosphere source contaminated by a deeper mantle source modified by subducted slab-derived products. Sr-87/Sr-86 ratios and petrological evidence show that these lavas have been intensely altered by mid-oceanic hydrothermalism as well as by serpentinites, which are interpreted as exhumed mantle peridotites. The gabbros have almost the same geochemical composition as related pillow-lavas: (La/Yb)(N) = 0.2-2.3; (Nb/Th)(N) = 0.1-2.8; (Nd-143/Nd-144)(i) = 0.51264-0.51276: (Sr-87/Sr-86)(i) = 0.70386-0.70557; (Pb-207/Pb-204)(i) = 15.4888-15.5391; (Pb-208/Pb-204)(i) = 37.2729-37.8713; (Pb-206/Pb-204)(i) = 17.6296-17.9683. Plagiogranites show major and trace element features similar to other Neo-Tethyan plagiogranites (La/Yb)(N) = 1.10-7.92; (Nb/Th)(N) = 0.10-0.94; but display a less radiogenic Nd isotopic composition than basalts [(Nd-143/Nd-144)(i) = 0.51263] and more radiogenic (Sr-87/Sr-86)(i) ratios. This oceanic crust sequence is covered by variable thicknesses of unaltered pillowed OIB alkaline lavas emplaced in marine conditions. Ar-40/Ar-39 dating of a single-grain amphibole phenocryst provides a Lower Cretaceous age of 117.3 +/- 0.9 Ma, which confirms a distinct formation age of the OIB lavas. The geochemical composition of these alkaline lavas is similar to plateau-lavas [(La/Yb)(N) = 6-14; (Nb/Th)(N) = 0.23-0.76; (Nd-143/Nd-144)(i) = 0.51262-0.51271; (Sr-87/Sr-86)(i) = 0.70338-0.70551; (Pb-207/Pb-204)(i) = 15.5439-15.6158; (Pb-208/Pb-204)(i) = 38.3724-39.3623; (Pb-206/Pb-204)(i) = 18.4024-19.6744].;They have significantly more radiogenic lead isotopic compositions than phiolitic rocks, and fit the geochemical compositions of hot-spot derived lavas mixed with various proportions of oceanic mantle. In addition, this oceanic + plateau sequence is covered by Upper Cretaceous calc-alkaline lavas: (La/Yb)(N) = 2.07-2.31; (Nb/Th)(N) = 0.08-0.15; (Nd-144/Nd-143)(i) = 0.51271-0.51282; (Sr-117/Sr-116)(i) = 0.70452-0.70478), which were likely formed in a supra-subduction zone environment. During the late Lower to early Upper Cretaceous period, hot-spot related magmatism related to plateau events may have led to significant crustal thickening in various zones of the Middle-eastern Neotethys. These processes have likely hindered subduction of some of the hot and thickened oceanic crust segments, and allowed them to be obducted over small continental blocks such as the South Armenian Block.
ISSN: 0024-4937

hal-00443855
https://hal.archives-ouvertes.fr/hal-00443855
DOI : 10.1016/j.lithos.2009.02.006

Éditeur(s) : American society for microbiology
Résumé : Vibrio nigripulchritudo, the etiological agent of Litopenaeus stylirostris summer syndrome, is responsible for mass mortalities of shrimp in New Caledonia. Epidemiological studies led to the suggestion that this disease is caused by an emergent group of pathogenic strains. Genomic subtractive hybridization was carried out between two isolates exhibiting low and high virulence. Our subtraction library was constituted of 521 specific fragments; 55 of these were detected in all virulent isolates from our collection (n = 32), and 13 were detected only in the isolates demonstrating the highest pathogenicity (n = 19), suggesting that they could be used as genetic markers for high virulence capacity. Interestingly, 10 of these markers are carried by a replicon of 11.2 kbp that contains sequences highly similar to those of a plasmid detected in Vibrio shilonii, a coral pathogen. The detection of this plasmid was correlated with the highest pathogenicity status of the isolates from our collection. The origin and consequence of this plasmid acquisition are discussed.
Applied and environmental microbiology (depuis 1953) (0099-2240) (American society for microbiology), 2008-05 , Vol. 74 , N. 10 , P. 3038-3047

Droits : 2008 American Society for Microbiology
http://archimer.ifremer.fr/doc/2008/publication-4523.pdf
DOI:10.1128/AEM.02680-07
http://archimer.ifremer.fr/doc/00000/4523/

Éditeur(s) : HAL CCSD BioMed Central
Résumé : International audience
Background: Color polymorphism in the nacre of pteriomorphian bivalves is of great interest for the pearl culture industry. The nacreous layer of the Polynesian black-lipped pearl oyster Pinctada margaritifera exhibits a large array of color variation among individuals including reflections of blue, green, yellow and pink in all possible gradients. Although the heritability of nacre color variation patterns has been demonstrated by experimental crossing, little isknown about the genes involved in these patterns. In this study, we identify a set of genes differentially expressed among extreme color phenotypes of P. margaritifera using a suppressive and subtractive hybridization (SSH) method comparing black phenotypes with full and half albino individuals.Results: Out of the 358 and 346 expressed sequence tags (ESTs) obtained by conducting two SSH libraries respectively, the expression patterns of 37 genes were tested with a real-time quantitative PCR (RT-qPCR) approach by pooling five individuals of each phenotype. The expression of 11 genes was subsequently estimated for each individual in order to detect inter-individual variation. Our results suggest that the color of the nacre is partiallyunder the influence of genes involved in the biomineralization of the calcitic layer. A few genes involved in the formation of the aragonite tablets of the nacre layer and in the biosynthesis chain of melanin also showed differential expression patterns. Finally, high variability in gene expression levels were observed within the black phenotypes.Conclusions: Our results revealed that three main genetic processes were involved in color polymorphisms: the biomineralization of the nacreous and calcitic layers and the synthesis of pigments such as melanin, suggesting that color polymorphism takes place at different levels in the shell structure. The high variability of gene expression found within black phenotypes suggests that the present work should serve as a basis for future studies exploringmore thoroughly the expression patterns of candidate genes within black phenotypes with different dominant iridescent colors.
ISSN: 1471-2164

hal-01260141
https://hal.archives-ouvertes.fr/hal-01260141
https://hal.archives-ouvertes.fr/hal-01260141/document
https://hal.archives-ouvertes.fr/hal-01260141/file/Lemer-2015-BMCGenom-Identification.pdf
DOI : 10.1186/s12864-015-1776-x

Éditeur(s) : HAL CCSD Wiley-Blackwell
Résumé : International audience
Archaea may be involved in global energy cycles, and are known for their ability to interact with eukaryotic species (sponges, corals and ascidians) or as archaeal-bacterial consortia. The recently proposed phylum Thaumarchaeota may represent the deepest branching lineage in the archaeal phylogeny emerging before the divergence between Euryarchaeota and Crenarchaeota. Here we report the first characterization of two marine thaumarchaeal species from shallow waters that consist of multiple giant cells. One species is coated with sulfur-oxidizing g-Proteobacteria. These new uncultured thaumarchaeal species are able to live in the sulfide-rich environments of a tropical mangrove swamp, either on living tissues such as roots or on various kinds of materials such as stones, sunken woods, etc. These archaea and archaea/bacteria associations have been studied using light microscopy, transmission electron microscopy and scanning electron microscopy. Species identification of archaeons and the putative bacterial symbiont have been assessed by 16S small subunit ribosomal RNA analysis. The sulfur-oxidizing ability of the bacteria has been assessed by genetic investigation on alpha-subunit of the adenosine-5_- phosphosulfate reductase/oxidase's (AprA). Species identifications have been confirmed by fluorescence in situ hybridization using specific probes designed in this study. In this article, we describe two new giant archaeal species that form the biggest archaeal filaments ever observed. One of these species is covered by a specific biofilm of sulfur-oxidizing g-Proteobacteria. This study highlights an unexpected morphological and genetic diversity of the phylum Thaumarchaeota.
ISSN: 1462-2912

hal-00715219
https://hal.univ-antilles.fr/hal-00715219
DOI : 10.1111/j.1462-2920.2010.02309.x

Résumé : Dans le cadre du plan Etat-Région 1994-1998, un programme de conservatoire de souches a été initié au Laboratoire IFREMER de La Tremblade. Ce conservatoire a pour objectif d'acclimater différentes espèces ou souches d'huîtres creuses (genres Crassostrea et Saccostrea) afin d'acquérir des connaissances sur ces espèces et d'évaluer l'intérêt qu'elles pourraient présenter pour l'ostréiculture locale. L'importation d'espèces étrangères sur les côtes françaises est désormais strictement réglementée: la dissémination d'une nouvelle espèce peut se révéler néfaste d'un point de vue écologique et nuire aux productions existantes. De plus, ces huîtres peuvent être porteuses de pathogènes qui, s'il venaient à se répandre dans le milieu, pourraient toucher les stocks locaux. En conséquence, les huîtres importées sont strictement confinées au laboratoire dans une « salle de quarantaine » dont l'eau est traitée à l'ozone avant rejet afin d'éviter à la fois la dissémination des huîtres et d'éventuels pathogènes...

Droits : 1999 Ifremer
http://archimer.ifremer.fr/doc/00044/15514/12901.pdf
http://archimer.ifremer.fr/doc/00044/15514/

Résumé : La zone latérale des filaments branchiaux des bivalves Codakia orbiculata et Lucina pensylvanica est le lieu d'une symbiose chimioautotrophe avec des bactéries sulfo-oxydantes hébergées dans des cellules spécialisées, appelées bactériocytes. Dans cette étude, nous nous sommes proposés de déterminer les mécanismes qui sous-tendent la plasticité cellulaire et tissulaire observée au cours des processus de décolonisation et de recolonisation bactérienne. Pour ce faire, des individus collectés dans leur milieu naturel, ont été maintenus au laboratoire dans des bacs d'eau de mer filtrée en absence de nourriture et de soufre réduit, afin de provoquer la décolonisation bactérienne des filaments branchiaux. Lorsque la branchie apparaissait purgée de ses symbiotes, les individus ont été remis dans leur habitat naturel afin de provoquer sa recolonisation. L'analyse des branchies au cours de ces processus a fait appel à des techniques variées (histologie, immunohistochimie, hybridation in situ, cytométrie en flux, dosage des protéines et spectrométrie de fluorescence X). Les résultats obtenus ont permis de montrer que l'acquisition environnementale mise en évidence chez les juvéniles des Codakia se poursuivait tout au long de la vie des adultes. Cette étude a également permis une meilleure compréhension des mécanismes tissulaires sous-jacents à la plasticité du filament branchial en mettant en évidence les processus d'apoptose et de prolifération cellulaire qui ont lieu au cours des processus de décolonisation et de recolonisation. Ces processus s'accompagnent d'une variation de la teneur en soufre élémentaire, ainsi que de la taille relative et du contenu génomique des symbiotes
The lateral zone of gills filaments of coastal bivalves Codakia orbiculata and Lucina pensylvanica is the site of chemoautotrophic symbiosis with sulfur-oxidizing bacteria, housed in specialized cells called bacteriocytes. The objective of this thesis is to determine the mechanisms underlying cel1 plasticity and tissue plasticity observed in the lateral zone of gills filaments during the processes of bacterial decolonization and recolonization. In order to do this, the individuals collected in their natural habitat were maintained at the laboratory in seawater filtered tanks, without food and reduced sulfur, to cause bacterial decolonization. When the gills seemed to be purged, the individuals were returned to their natural habitat in order to cause the bacterial recolonization of gills filaments. The analysis of the gills during these processes involves several techniques (histology, immunohistochemistry, molecular hybridization, flow cytometry, total protein assays, protein sulfur assays, X-ray fluorescence spectrometry).This study shows that symbiont acquisition can occur during the entire life of Codakia bivalves. It also allows a better understanding of gills filaments plasticity by highlighting apoptosis and cell proliferation during decolonization and recolonization processes.Theses processes are accompanied with of elemental sufur, relative size and genomic content of symbiontes.

http://www.theses.fr/2011AGUY0461/document

Éditeur(s) : HAL CCSD Nature Publishing Group
Résumé : International audience
Genetic recombination occurs during meiosis, the key developmental programme of gametogenesis. Recombination in mammals has been recently linked to the activity of a histone H3 methyltransferase, PR domain containing 9 (PRDM9), the product of the only known speciation-associated gene in mammals. PRDM9 is thought to determine the preferred recombination sites--recombination hotspots--through sequence-specific binding of its highly polymorphic multi-Zn-finger domain. Nevertheless, Prdm9 knockout mice are proficient at initiating recombination. Here we map and analyse the genome-wide distribution of recombination initiation sites in Prdm9 knockout mice and in two mouse strains with different Prdm9 alleles and their F(1) hybrid. We show that PRDM9 determines the positions of practically all hotspots in the mouse genome, with the exception of the pseudo-autosomal region (PAR)--the only area of the genome that undergoes recombination in 100% of cells. Surprisingly, hotspots are still observed in Prdm9 knockout mice, and as in wild type, these hotspots are found at H3 lysine 4 (H3K4) trimethylation marks. However, in the absence of PRDM9, most recombination is initiated at promoters and at other sites of PRDM9-independent H3K4 trimethylation. Such sites are rarely targeted in wild-type mice, indicating an unexpected role of the PRDM9 protein in sequestering the recombination machinery away from gene-promoter regions and other functional genomic elements.
ISSN: 0028-0836

hal-00877666
https://hal.archives-ouvertes.fr/hal-00877666
DOI : 10.1038/nature11089
PUBMED : 22660327

Éditeur(s) : HAL CCSD Paris : Avancées cinématographiques
Résumé : International audience
ISSN: 0985-1402

hal-01571930
https://hal.archives-ouvertes.fr/hal-01571930
DOI : 10.4000

Éditeur(s) : HAL CCSD Wiley-Blackwell
Résumé : International audience
The shallow-water bivalve Codakia orbiculata which harbors gill-endosymbiotic sulfur-oxidizing g-proteobacteria can lose and acquire its endosymbionts throughout its life. Longterm starvation and recolonization experiments led to changes in the organization of cells in the lateral zone of gill filaments. This plasticity is linked to the presence or absence of gill-endosymbionts. Herein, we propose that this reorganization can be explained by three hypotheses: (a) a variation in the number of bacteriocytes and granule cells due to proliferation or apoptosis processes, (b) a variation of the volume of these two cell types without modification in the number, and (c) a combination of both number and cell volume variation. To test these hypotheses, we analyzed cell reorganization in terms of proliferation and apoptosis in adults submitted to starvation and returned to the field using catalyzed reporter deposition fluorescence in situ hybridization, immunohistochemistry, and structural analyses. We observed that cell and tissue reorganization in gills filaments is due to a variation in cell relative abundance that maybe associated with a variation in cell apparent volume and depends on the environment. In fact, bacteriocytes mostly multiply in freshly collected and newly recolonized individuals, and excess bacteriocytes are eliminated in later recolonization stages. We highlight that host tissue regeneration in gill filaments of this symbiotic bivalve can occur by both replication of existing cells and division of undifferentiated cells localized in tissular bridges, which might be a tissue-specific multipotent stem cell zone.
Microscopy Research and Technique

hal-00743036
https://hal-uag.archives-ouvertes.fr/hal-00743036

Éditeur(s) : HAL CCSD CERAMAC
Résumé : International audience
Nous présentons les résultats de la mise en œuvre du " jeu de territoire " réalisé par des élèves-ingénieurs dans le cadre de la révision du plan stratégique menée par les acteurs du Témiscamingue (Québec, Canada). Trois phases de réflexion et d'argumentation favorisant une élaboration collaborative : la constitution d'un portait du territoire et d'un diagnostic des enjeux, l'élaboration de scénarios d'évolution prospective à 15 ans et l'énoncé de premières pistes d'orientation pour le prochain plan stratégique. Nous discutons les apports du jeu comme dispositif d'apprentissage collectif pour la mobilisation et le partage des connaissances et comme dispositif de production iconographique pour la construction de représentations partagées et leur appropriation collective. Nous mettons en évidence l'intérêt d'une hybridation des compétences et des savoirs, entre recherche, formation et action, pour faciliter la mobilisation des acteurs dans les démarches participatives de conception de projets de territoire.
Développement durable des territoires : de la mobilisation des acteurs aux démarches participatives
Clermont-Ferrand, France

hal-00982919
https://hal-agroparistech.archives-ouvertes.fr/hal-00982919

Éditeur(s) : HAL CCSD
Résumé : International audience
Clear cell renal cell carcinoma (ccRCC) has a poor prognosis with a 50% risk of metastases. Little is known about the phenotypic and molecular profiles of metastases regarding their corresponding primary tumors. This study aimed to screen phenotypic and genotypic differences between metastases and their corresponding primary tumors. We selected four cases with available frozen material. The histological, immunohistochemical (VEGFA, CD31, SMA, Ki67, p53, PAR-3), FISH (VHL gene), next-generation sequencing (VHL and c-MET genes), multiplex ligation-dependent probe amplification, and array-(comparative genomic hybridization) CGH analyses were realized. Metastases were nodal, hepatic (synchronous), adrenal, and pulmonary (metachronous). High-grade tumor cells were significantly more frequent in metastases (p = 0.019). Metastases and high-grade zones of primary tumors shared similar characteristics compared to low-grade zones: a lower microscopic vascular density (43.5 vs 382.5 vessels/mm(2); p = 0.0027), a higher expression of VEGF (73 vs 10%, p = 0.045), Ki67 (37.6 vs 8.3%; p = 0.011), and p53 (54 vs 10.6%; p = 0.081), and a cytoplasmic and membranous PAR-3 staining. Metastases exhibited more chromosomal imbalances than primary tumors in total (18.75 ± 6.8; p = 0.044) with more genomic gains (13.5 ± 7; p = 0.013). The loss of chromosome 9 and gain of Xq were found in both primary tumors and metastases but gains of loci or chromosomes 2p, 3q, 5, 8q, 12, and 20 were only found in metastases. The VHL gene status was similar in each tumor couple. Although metastases and primary tumors share common histological features, this study highlights chromosomal differences specific to metastases which could be involved in ccRCC metastatic evolution.
Virchows Archiv

hal-01560281
https://hal-univ-rennes1.archives-ouvertes.fr/hal-01560281
DOI : 10.1007/s00428-017-2124-0
PUBMED : 28488172

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
Geochemical studies of primitive basalts have documented the presence of crustal-derived garnet pyroxenite in their mantle sources. The processes whereby melts with the signature of garnet pyroxenite are produced in the mantle are, however, poorly understood and somewhat controversial. Here we investigate a natural example of the interaction between melts of garnet pyroxenite derived from recycled plagioclase-rich crust and surrounding mantle in the Ronda peridotite massif. Melting of garnet pyroxenite at ∼1.5 GPa generated spinel websterite residues with MREE/HREE fractionation and preserved the positive Eu anomaly of their garnet pyroxenite precursor in whole-rock and clinopyroxene. Reaction of melts from garnet pyroxenite with depleted surrounding peridotite generated secondary fertile spinel lherzolite. These secondary lherzolites differ from common spinel lherzolite from Ronda and elsewhere by their lower-Mg# in clinopyroxene, orthopyroxene and olivine, lower-Cr# in spinel and higher whole-rock Al2O3, CaO, Sm/Yb and FeO⁎ at a given SiO2. Remarkably, secondary spinel lherzolite shows the geochemical signature of ghost plagioclase in the form of positive Eu and Sr anomalies in whole-rock and clinopyroxene, reflecting the transfer of a low-pressure crustal imprint from recycled pyroxenite to hybridized peridotite. Garnet pyroxenite melting and melt-peridotite interaction, as shown in the Ronda massif, may explain how the signature of subducted or delaminated crust is transferred to the mantle and how a garnet pyroxenite component is introduced into the source region of basalts. The efficiency of these processes in conveying the geochemical imprint of crustal-derived garnet pyroxenite to extruded lavas depends on the reactivity of pyroxenite melt with peridotite and the mantle permeability, which may be controlled by prior refertilization reactions similar to those documented in the Ronda massif. Highly fertile heterogeneities produced by pyroxenite-peridotite interaction, such as secondary spinel lherzolite in Ronda, may nucleate magmatic channels that remain chemically isolated from the ambient mantle and act as preferential pathways for melts with the signature of recycled crust.
ISSN: 0012-821X

hal-00814010
https://hal.archives-ouvertes.fr/hal-00814010
DOI : 10.1016/j.epsl.2012.11.047

Éditeur(s) : HAL CCSD Public Library of Science
Résumé : International audience
Brain-derived neurotrophic factor (BDNF), a member of the neurotrophin family, has emerged as an active mediator in many essential functions in the central nervous system of mammals. BDNF plays significant roles in neurogenesis, neuronal maturation and/or synaptic plasticity and is involved in cognitive functions such as learning and memory. Despite the vast literature present in mammals, studies devoted to BDNF in the brain of other animal models are scarse. Zebrafish is a teleost fish widely known for developmental genetic studies and is emerging as model for translational neuroscience research. In addition, its brain shows many sites of adult neurogenesis allowing higher regenerative properties after traumatic injuries. To add further knowledge on neurotrophic factors in vertebrate brain models, we decided to determine the distribution of bdnf mRNAs in the larval and adult zebrafish brain and to characterize the phenotype of cells expressing bdnf mRNAs by means of double staining studies. Our results showed that bdnf mRNAs were widely expressed in the brain of 7 days old larvae and throughout the whole brain of mature female and male zebrafish. In adults, bdnf mRNAs were mainly observed in the dorsal telencephalon, preoptic area, dorsal thalamus, posterior tuberculum, hypothalamus, synencephalon, optic tectum and medulla oblongata. By combining immunohistochemistry with in situ hybridization, we showed that bdnf mRNAs were never expressed by radial glial cells or proliferating cells. By contrast, bdnf transcripts were expressed in cells with neuronal phenotype in all brain regions investigated. Our results provide the first demonstration that the brain of zebrafish expresses bdnf mRNAs in neurons and open new fields of research on the role of the BDNF factor in brain mechanisms in normal and brain repairs situations.
ISSN: 1932-6203

hal-01359562
https://hal-univ-rennes1.archives-ouvertes.fr/hal-01359562
DOI : 10.1371/journal.pone.0158057
PUBMED : 27336917