Éditeur(s) : Edp Sciences S A
Résumé : Sperm characteristics of scallops have not been well described in the scientific literature. The effects of sperm release technique (thermal shock versus serotonin injection), of sperm collection technique (testis sampling versus serotonin injection), of sperm sampling location along the genital tract, of in vitro sperm maturation, and of time post activation on scallop sperm characteristics were assessed in the present work. Whatever sperm release technique used, no significant differences were observed regarding the percentage of motile spermatozoa and the velocity of the average path (YAP). Compared to testicular sperm, a higher percentage of motile spermatozoa, YAP and intracellular adenosine triphosphate (ATP) content were observed for sperm shed after serotonin injection. From the distal part of testes up to the gonopore, an increase of the percentage of motile spermatozoa and YAP was assessed, suggesting a sperm 'maturation process' along the genital ducts. A higher increase in the percentage of motile sperm was recorded during a 5 mm incubation of testicular sperm in seawater containing 2 mM serotonin and seawater containing 10 mM caffein compared to seawater (control). In addition, a higher YAP was assessed, incubating testicular sperm in caffein, compared to control or serotonin. Then, the percentage of motile spermatozoa, YAP and intracellular ATP content exhibited a progressive reduction during the 10 h swimming period. Mean values of the percentage of motile spermatozoa, YAP, sperm track linearity (LIN) and intracellular ATP content recorded at the beginning of the movement period for sperm samples collected after intragonadal serotonin injection, were 82 +/- 7%, 162 +/- 15 mu m s(-1), 0.33 +/- 0.12 and 212 +/- 133 nmol x 10(-9) spermatozoa (n = 9 males), respectively. The present study confirms the existence of a sperm "maturation process" along scallop genital ducts. In addition, the cessation of scallop sperm movement can be explained by the exhaustion of ATP content at the end of the movement phase.
Aquatic Living Resources (0990-7440) (Edp Sciences S A), 2013-07 , Vol. 26 , N. 3 , P. 215-220

Droits : EDP Sciences, IFREMER, IRD 2013
http://archimer.ifremer.fr/doc/00157/26852/24983.pdf
DOI:10.1051/alr/2013048
http://archimer.ifremer.fr/doc/00157/26852/

Éditeur(s) : HAL CCSD Wiley
Résumé : International audience
Motility and invasiveness events require specific intracellular signaling cascade activations. In cancer liver cells, one of these mechanisms could involve the MAPK MEK/ERK cascade activation which has been shown over expressed and activated in hepatocellular carcinoma. To study whether the MEK/ERK cascade is involved in the motility of HCC, we examined the effect of MEK inhibitor and ERK2 silencing using monolayer wound-healing assays and fluoroblock invasion systems. Evidence was provided that the MAPK cascade is a key transduction pathway which controls HCC cells motility and invasiveness. We could disconnect proliferation to motility using mitomycin C and we established that RNAi-mediated inhibition of ERK2 led to strongly reduced cell motility. To improve our understanding, we analysed the regulation and the role of urokinase receptor (uPAR) in this process. We provided evidence that uPAR was under a MEK/ERK dependent mechanism and blocking uPAR activity using specific antagonist or inhibiting its expression by RNA interference which resulted in complete inhibition of motility. Moreover, we found in MAPK inhibited cultures and in uPAR silencing cells that p70S6K phosphorylation on residue Thr-389 was significantly reduced, whereas Ser-421/Thr-424 phosphorylation did not change. We highlighted that the FRAP/mTOR pathway did not affect motility and Thr-389 phosphorylation. Furthermore, we demonstrated that p70S6K inhibition by RNA interference completely inhibited hepatocarcinoma cell motility. Therefore, targeting uPAR and/or MEK/ERK/S6K by RNA interference could be a major therapeutic strategy for the future treatment of invasive hepatocarcinoma cells.
ISSN: 0021-9541

hal-00697044
https://hal.archives-ouvertes.fr/hal-00697044
DOI : 10.1002/jcp.21049
PUBMED : 17427199

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
BACKGROUND: Evidence of human sexual transmission during Zika virus emergence is a matter of concern, particularly in procreation, but to date, kinetics of seminal shedding and the effects of infection on human reproductive function have not been described. To investigate the effects of Zika virus infection on semen and clearance of Zika virus from semen and body fluids, we aimed to study a cohort of Zika virus-infected men. METHODS: This prospective observational study recruited men presenting with acute Zika virus infection at Pointe-à-Pitre University Hospital in Guadeloupe, French Caribbean, where a Zika virus outbreak occurred between April and November, 2016. Blood, urine, and semen were collected at days 7, 11, 20, 30, 60, 90, and 120 after symptom onset, and semen characteristics, such as total sperm count, sperm motility, vitality, and morphology, and reproductive hormone concentrations, such as testosterone, inhibin, follicle-stimulating hormone, and luteinising hormone, were assessed. At days 7, 11, and 20, semen was processed to isolate motile spermatozoa. Zika virus RNA was detected by RT-PCR using whole blood, serum, urine, seminal plasma, semen cells, and motile spermatozoa fractions. Zika virus was isolated from different sperm fractions on Vero E6 cultures. FINDINGS: 15 male volunteers (mean age 35 years [SD 5; range 25-44) with acute Zika virus infection and positive Zika virus RNA detection in blood or urine were enrolled. Total sperm count was decreased from median 119 × 10(6) spermatozoa (IQR 22-234) at day 7 to 45·2 × 10(6) (16·5-89·6) at day 30 and 70 × 10(6) (28·5-81·4) at day 60, respectively, after Zika virus infection. Inhibin values increased from 93·5 pg/mL (IQR 55-162) at day 7 to 150 pg/mL (78-209) at day 120 when total sperm count recovered. In motile spermatozoa obtained after density gradient separation, Zika virus RNA was found in three of 14 patients at day 7, four of 15 at day 11, and four of 15 at day 20, and replication-competent virus was found in the tested patient. Seminal shedding kinetics seemed heterogeneous among patients. Whole blood was the fluid most frequently positive for Zika virus RNA (62 of 92 samples) and three patients remained positive at day 120. INTERPRETATION: Semen alterations early after acute Zika virus infection might affect fertility and could be explained by virus effects on the testis and epididymis. Frequency of shedding and high viral load in semen, together with the presence of replicative virus in a motile spermatozoa fraction, can lead to Zika virus transmission during sexual contact and assisted reproduction procedures. Whole blood seems to be the best specimen for Zika virus RNA detection, diagnosis, and follow-up. FUNDING: Agence de la Biomédecine/Agence Régionale de Santé de la Guadeloupe/Inserm-REACTing.
ISSN: 0140-6736

hal-01647078
https://hal-univ-rennes1.archives-ouvertes.fr/hal-01647078
DOI : 10.1016/S1473-3099(17)30444-9
PUBMED : 28838639

Éditeur(s) : HAL CCSD Nature Publishing Group
Résumé : International audience
Epithelial-to-mesenchymal transition (EMT) promotes cell motility, which is important for the metastasis of malignant cells, and blocks CD95-mediated apoptotic signaling triggered by immune cells and chemotherapeutic regimens. CD95L, the cognate ligand of CD95, can be cleaved by metalloproteases and released as a soluble molecule (cl-CD95L). Unlike transmembrane CD95L, cl-CD95L does not induce apoptosis but triggers cell motility. Electron paramagnetic resonance was used to show that EMT and cl-CD95L treatment both led to augmentation of plasma membrane fluidity that was instrumental in inducing cell migration. Compaction of the plasma membrane is modulated, among other factors, by the ratio of certain lipids such as sphingolipids in the membrane. An integrative analysis of gene expression in NCI tumor cell lines revealed that expression of ceramide synthase-6 (CerS6) decreased during EMT. Furthermore, pharmacological and genetic approaches established that modulation of CerS6 expression/activity in cancer cells altered the level of C16-ceramide, which in turn influenced plasma membrane fluidity and cell motility. Therefore, this study identifies CerS6 as a novel EMT-regulated gene that has a pivotal role in the regulation of cell migration.Oncogene advance online publication, 17 March 2014; doi:10.1038/onc.2014.55.
ISSN: 0950-9232

hal-01063558
https://hal.archives-ouvertes.fr/hal-01063558
https://hal.archives-ouvertes.fr/hal-01063558/file/Down-regulation%20of%20ceramide_accepted.pdf
DOI : 10.1038/onc.2014.55
PUBMED : 24632610

Éditeur(s) : HAL CCSD Public Library of Science
Résumé : 51 pages; 15figures; 3 tables, accepted for publication in PloS ONE
International audience
We present a study about AFM imaging of living, moving or self-immobilized, bacteria in their genuine physiological liquid medium. No external immobilization protocol, neither chemical nor mechanical, was needed. For the first time, the native gliding movements of Gram-negative Nostoc cyanobacteria upon the surface, at speeds up to 900microns/h, were studied by AFM. This was possible thanks to an improved combination of a gentle sample preparation process and an AFM procedure based on fast and complete force-distance curves made at every pixel, drastically reducing lateral forces. No limitation in spatial resolution or imaging rate was detected. Gram-positive and non-motile R. wratislaviensis bacteria were studied as well. From the approach curves, Young modulus and turgor pressure were measured for both strains at different gliding speeds and are ranging from 20±3 to 105±5MPa and 40±5 to 310±30kPa depending on the bacterium and the gliding speed. For Nostoc, spatially limited zones with higher values of stiffness were observed. The related spatial period is much higher than the mean length of Nostoc nodules. This was explained by an inhomogeneous mechanical activation of nodules in the Nostoc. We also observed the presence of a soft extra cellular matrix (ECM) around the Nostoc. Both strains left a track of polymeric slime with variable thicknesses. For R. wratislaviensis, it is equal to few hundreds of nanometers, likely to promote its adhesion to the sample. While gliding, the Nostoc secretes a slime layer the thickness of which is in the nanometer range and increases with the gliding speed.
ISSN: 1932-6203

hal-00769765
https://hal.archives-ouvertes.fr/hal-00769765
https://hal.archives-ouvertes.fr/hal-00769765v3/document
https://hal.archives-ouvertes.fr/hal-00769765/file/REsubmission_In-situ_determination_Dhahri_Plos_One_R2_Hal.pdf

Éditeur(s) : HAL CCSD American Association for Cancer Research
Résumé : International audience
Triple-negative breast cancers (TNBC) lacking estrogen and progesterone receptors and HER2 amplification have a relatively high risk of metastatic dissemination, but the mechanistic basis for this risk is not understood. Here we report that serum levels of CD95L are higher in TNBC patients compared to other breast cancer patients. Metalloprotease-mediated cleavage of CD95L expressed by endothelial cells surrounding tumors generates a gradient that promotes cell motility, due to formation of an unconventional CD95-containing receptosome termed the motility-inducing signaling complex. Formation of this complex was instrumental for Nox3-driven ROS generation. Mechanistic investigations revealed a Yes-Orai1-EGFR-PI3K pathway that triggered migration of TNBC cells exposed to CD95L. Our findings establish a pro-metastatic function for metalloprotease-cleaved CD95L in triple-negative breast cancers, revisiting its role in carcinogenesis.
ISSN: 0008-5472

hal-00873634
https://hal.archives-ouvertes.fr/hal-00873634
PUBMED : 24072745
DOI : 10.1158/0008-5472.CAN-13-1794

Éditeur(s) : HAL CCSD Society for the Study of Reproduction
Résumé : International audience
Spermmotility notably depends on the structural integrity of the flagellum and the regulation ofmicrotubule dynamics. Although researchers have started to use " omics" techniques to characterize the human sperm's molecular landscape, the constituents responsible for the assembly, organization, and dynamics of the flagellum microtubule have yet to be fully defined. In this study, we defined a core set of 116 gene products associated with the human sperm microtubulome (including products potentially involved in abnormal ciliary phenotypes and male infertility disorders). To this end, we designed and applied an integrated genomics workflow and combined relevant proteomics, transcriptomics, and interactomics datasets to reconstruct a dynamic interactome map. By further integrating phenotypic information, we defined a disease-interaction network; this enabled us to highlight a number of novel factors potentially associated with altered sperm motility and male fertility. Lastly, we experimentally validated the expression pattern of two candidate genes (CUL3 and DCDC2C) that had never previously been associated with male germline differentiation. Our analysis suggested that CUL3 and DCDC2C's products have important roles in the sperm flagellum. Taken as a whole, our results demonstrate that an integrated genomics strategy can highlight relevant molecular factors in specific sperm components. This approach could be easily extended by including other " omics" data (from asthenozoospermic men, for example) and identifying other critical proteins from the human sperm microtubulome. Summary Sentence Although researchers have started to use "omics" techniques to characterize the human sperm's molecular landscape, the constituents responsible for the assembly, organization, and dynamics of the flagellum microtubule have yet to be fully defined.
ISSN: 0006-3363

hal-01515563
https://hal-univ-rennes1.archives-ouvertes.fr/hal-01515563
DOI : 10.1095/biolreprod.116.143479
PUBMED : 28395323

Éditeur(s) : HAL CCSD Nature Publishing Group
Résumé : International audience
Transmembrane CD95L (Fas ligand) can be cleaved to release a promigratory soluble ligand, cl-CD95L, which can contribute to chronic inflammation and cancer cell dissemination. The motility signaling pathway elicited by cl-CD95L remains poorly defined. Here, we show that in the presence of cl-CD95L, CD95 activates the Akt and RhoA signaling pathways, which together orchestrate an allosteric activation of the Na+/H+ exchanger NHE1. Pharmacologic inhibition of Akt or ROCK1 independently blocks the cl-CD95L-induced migration. Confirming these pharmacologic data, disruption of the Akt and ROCK1 phosphorylation sites on NHE1 decreases cell migration in cells exposed to cl-CD95L. Together, these findings demonstrate that NHE1 is a novel molecular actor in the CD95 signaling pathway that drives the cl-CD95L-induced cell migration through both the Akt and RhoA signaling pathways.
ISSN: 2045-2322

hal-01334067
https://hal-univ-rennes1.archives-ouvertes.fr/hal-01334067
https://hal-univ-rennes1.archives-ouvertes.fr/hal-01334067/document
https://hal-univ-rennes1.archives-ouvertes.fr/hal-01334067/file/Cleaved%20FAS%20ligand%20CC-BY.pdf
DOI : 10.1038/srep28008

Éditeur(s) : HAL CCSD Cushman Foundation for Foraminiferal Research
Résumé : International audience
Benthic foraminifera are heterotrophic protists that utilize different trophic mechanisms and nutritional resources. They exhibit a wide range of trophic behaviours: selective (grazing) and indiscriminate herbivory, symbiosis, carnivory, parasitism, uptake of dissolved organic matter, passive suspension feeding and, most commonly, deposit feeding. The benthic foraminifera Ammonia tepida, previously known as an herbivore, fed as a carnivore in laboratory experiments where mobile metazoans were provided. We observed predation on the three types of metazoans provided: nematodes, copepods, and a larval gastropod. This foraminifera used its pseudopodial network to entrap the invertebrates, which were then stripped of their soft internal tissues within 24 hours. Our experiments are the first to demonstrate that Ammonia tepida, despite its limited motility, is able to utilize larger mobile animals as a food source. The great abundance of small metazoans in most marine environments suggests that they are a food source for foraminifera. Further study of foraminiferal feeding strategies will enhance our understanding of their role in marine communities.
ISSN: 0096-1191

hal-01248040
https://hal.archives-ouvertes.fr/hal-01248040
https://hal.archives-ouvertes.fr/hal-01248040/document
https://hal.archives-ouvertes.fr/hal-01248040/file/dupuy%20et%20al%202010.pdf

Éditeur(s) : HAL CCSD
Résumé : contient des versions PDF d'articles scientifiques (versions éditeur)
Spectrins are actin binding proteins that constitute the main components of membrane skeletons, the protein network located under the plasma membrane. Erythroid or non erythroid (in this case, they are called fodrins), spectrins play an important structural function in the membrane as demonstrated in the red blood cell. Spectrins are composed of two long α and β chains, associated in tetramers (αβ)2, forming the long flexible filaments of the network. Both chains are composed of repeating units which are folded in a triple helical arrangement (A, B and C helices), except for segment α10 which corresponds to a Src Homology 3 domain (SH3). The head-to-head interaction between dimers implies the N-terminal end of α chain and the C-terminal end of β chain. A model was proposed for the tetramerization site of spectrin : the two A and B helices of the last repeat of α chain interact with the C helix of the β chain in order to constitute a triple-helical structure similar to the repeats along the remainder of spectrin molecule. This model was first inferred from the relationship between the severity of the spectrin self-association defect and the location of the underlying mutations found in hereditary elliptocytosis (HE). Using recombinant peptides we defined the region, on both chains, which was sufficient and necessary to generate a fully functional tetramerization site. Producing peptides carrying a βHE mutation, we reproduced the tetramerization defect as observed in red blood cells of patients.
Finally, the presence of an SH3 domain probably gives to spectrins new functions which are different from the stability of the membrane. After contesting the existence of interaction between the fodrin SH3 domain and the α subunit of epithelial sodium channel sensitive to amiloride, we searched for partners of this domain, by screening a rat kidney library with the yeast two-hybrid system. We identified severals proteins implicated in the actin polymerization asoociated with motility or cell differenciation, suggesting that SH3 domain could play a part in this process.
Les spectrines, protéines liant l'actine, sont des constituants majeurs du squelette membranaire, réseau multiprotéique localisé sous la membrane plasmique. Érythroïdes ou non érythroïdes (dans ce cas, on les appelle fodrines), les spectrines ont un rôle structural important dans la membrane comme cela a déjà été démontré, pour la spectrine, dans le globule rouge. Elles sont constituées de deux longues chaînes a et ß associées côte à côte en tétramères (aß)2 qui forment les longs filaments du réseau. Chacune des chaînes est composée par la répétition de segments homologues, 22 pour a et 17 pour ß. Ces segments sont constitués de trois hélices a (hélices A, B et C) repliées sur elles-mêmes. Cette succession de structures trihélicoïdales est parfois interrompue par un domaine particulier comme le domaine SH3 (Src Homology 3) présent au milieu de la chaîne a. Les tétramères (aß)2 de spectrine constituent les filaments du squelette membranaire. L'interaction tête-à-tête de deux dimères aß implique les extrémités NH2 de la chaîne a et COOH de la chaîne ß. D'une part la sévérité du défaut d'auto-association et la localisation des mutations associées à celui-ci et d'autre part, les séquences en acides aminés des extrémités impliquées dans le site d'auto-association ont permis de proposer un modèle : la première hélice C isolée de la chaîne a pourrait s'associer aux deux dernières hélices A et B de la chaîne ß pour reconstituer une unité conformationnelle trihélicoïdale semblable à celles observées le long de la molécule. Un défaut dans la formation du tétramère est le support moléculaire le plus fréquemment observé dans les elliptocytoses héréditaires (HE). À l'aide de peptides recombinants, nous avons défini, sur les deux chaînes, les régions nécessaires et suffisantes possédant les caractéristiques pleinement fonctionnelles du site de tétramérisation. Nous avons ensuite, par mutagenèse dirigée, reproduit le lien entre la présence de mutations HE localisées dans les hélices A ou B et le défaut d'auto-association observé dans les globules rouges de patients HE. La présence d'un domaine SH3 localisé au milieu de la chaîne a confère probablement aux spectrine des fonctions autres que le maintien et la stabilité de la membrane. Les SH3, petits domaines protéiques, participent aux interactions protéine/protéine. Le seul partenaire connu du domaine SH3 de la fodrine était la sous-unité a du canal sodium sensible à l'amiloride (ENaC) mais la fonction de ce complexe n'était pas encore caractérisée. À l'aide de différentes méthodes, nous avons remis en cause l'interaction directe entre ENaC et le SH3 de la fodrine. La fonction de ce domaine SH3 étant liée à la nature de son ligand, nous avons donc recherché les partenaires putatifs du domaine SH3 de la fodrine par la technique du double-hybride. 29 partenaires ont été identifiés, regroupés en 19 familles et 10 clones isolés. La spécificité des interactions a été étudiée à la fois par double-hybride, à l'aide de mutants du domaine SH3 de la fodrine produits par mutagenèse dirigée. Les interactions vis-à-vis d'autres domaines SH3 (spectrine ou une protéine de levure non relatée Scd2) ont été également analysées. Enfin, la spécificité de certains partenaires a été confirmée par des études d'interactions in vitro. Deux des protéines les plus spécifiques du domaine SH3 de la fodrine sont des protéines tyrosine-phosphatase PTP. La première est l'isoforme A de PTP de faible poids moléculaire (LMPTPA) mais l'interaction n'a pas été confirmée in vitro. La deuxième, TD14, est une nouvelle PTP dont la seule fonction connue est d'inhiber la formation des foyers tumoraux des cellules surexprimant l'oncogène Ha-ras. Ces PTP pourraient soit déphosphoryler la fodrine, soit être recrutées sous la membrane pour déphosphoryler une autre cible. Nous avons également identifié trois partenaires (N-WASP, Evl et une protéine de la famille des formines) suggérant que les domaines SH3 des spectrines pourraient être impliqués dans les processus de polymérisation de l'actine liés à la mobilité ou la différenciation cellulaire. Mot clés : spectrine, fodrine, tétramérisation, SH3, double-hybride, polymérisation de l'actine
https://tel.archives-ouvertes.fr/tel-00284819

Droits : info:eu-repo/semantics/OpenAccess
tel-00284819
https://tel.archives-ouvertes.fr/tel-00284819
https://tel.archives-ouvertes.fr/tel-00284819/document
https://tel.archives-ouvertes.fr/tel-00284819/file/Nicolas_1999_-_These.pdf

Éditeur(s) : HAL CCSD Microbiology Society
Résumé : International audience
An actinobacterial strain, designated ViU22(T), was isolated from a natural uranium-rich soil and was studied using a polyphasic approach. Cells formed orange-pigmented colonies, were rod-shaped, Gram-positive (non-staining method), non-motile and non-spore-forming. This organism grew in 0-4.5 % (w/v) NaCl and at 15-37 °C, with optimal growth occurring in 0.5 % (w/v) NaCl and at 30 °C. Comparative 16S rRNA gene sequence analysis revealed that the strain ViU22(T) belonged to the genus Microbacterium. It exhibited highest 16S rRNA gene sequence similarity with the type strains of Microbacterium testaceum (98.14 %) and Microbacterium binotii (98.02 %). The DNA-DNA relatedness of strains ViU22(T) with the most closely related type strains Microbacterium testaceum and Microbacterium binotii DSM 19164(T) was 20.10 % (± 0.70) and 28.05 % (± 0.35), respectively. Strain ViU22(T) possessed a type B2β peptidoglycan with partial substitution of glutamic acid by 3-hydroxy glutamic acid. The major menaquinones were MK-11 and MK-12. Major polar lipids detected in the strain ViU22(T) were diphosphatidylglycerol, phosphatidylglycerol, an unknown phospholipid and unknown glycolipids. The predominant fatty acids were anteiso-C15 : 0, anteiso-C17 : 0 and iso-C16 : 0, a pattern reported for other Microbacterium species. The major cell-wall sugars were galactose, xylose and mannose and the DNA G+C content was 71 mol%. Together, the DNA-DNA hybridization results and the differentiating phenotypic characteristics, showed that strain ViU22(T) should be classified as the type strain of a novel species within the genus Microbacterium, for which the name Microbacterium lemovicicum sp. nov. is proposed. The type strain is ViU22(T) ( = ATCC BAA-2396(T) = CCUG 62198(T) = DSM 25044(T)).
ISSN: 1466-5026

hal-01561095
https://hal-amu.archives-ouvertes.fr/hal-01561095
PUBMED : 23264499
DOI : 10.1099/ijs.0.048454-0

Éditeur(s) : HAL CCSD
Résumé : International audience
In addition to soluble factors, mechanical constraints and extracellular matrix stiffness are important regulators of cell fate that are mediated by cytoskeletal modifications. The EMT (epithelial-mesenchymal transition) that occurs during normal development and malignant progression is a typical example of the phenotypic switch associated with profound actin remodelling and changes in gene expression. For instance, actin dynamics control motile cell functions in EMT, in part, through regulating the subcellular localization of the myocardin-related transcription factor MKL1 (megakaryoblastic leukaemia translocation 1), a co-activator of SRF (serum-responsive factor). In the present paper, we show that MKL1 participates also to the control of the cellular switch between growth and quiescence. Experimental disconnection between MKL1 and G-actin (globular actin), by using an MKL1 mutant or enhancing the F (filamentous)-/G-actin ratio, generates a widely open chromatin state and a global increase in biosynthetic activity, classically associated with cell growth. Conversely, G-actin accumulation favours nuclear condensation and cell quiescence. These large-scale chromatin changes rely upon extensive histone modifications, exemplified by that of H3K9 (H3 Lys9) shifting from trimethylation, a heterochromatin mark, to acetylation, a mark of euchromatin. The present study provides the first evidence for a global reversible hetero/euchromatinization phenomenon triggered by the actin/MKL1 signalling pathway.
The Biochemical Journal

hal-01063933
https://hal.archives-ouvertes.fr/hal-01063933
DOI : 10.1042/BJ20131240
PUBMED : 24762104

Éditeur(s) : HAL CCSD Taylor & Francis Open
Résumé : International audience
Our recent findings indicate that cells exposed to transmembrane (m-CD95L) or metalloprotease-cleaved CD95L (cl-CD95L) undergo a localized Ca(2+)entry that not only inhibits the initial steps of the CD95-mediated apoptotic signal but also promotes cell motility. Based on recent findings published on the non-apoptotic signals induced by CD95, we discuss how m-CD95L and cl-CD95L diverging by their stoichiometry could both contribute to the immune response by first recruiting activated T lymphocytes in the inflamed area and later by eliminating infected and transformed cells.
ISSN: 1942-0889

hal-00873761
https://hal.archives-ouvertes.fr/hal-00873761
https://hal.archives-ouvertes.fr/hal-00873761/document
https://hal.archives-ouvertes.fr/hal-00873761/file/The_CD95_signaling_pathway-accepted.pdf
DOI : 10.4161/cib.18888

Éditeur(s) : HAL CCSD Wiley-Blackwell
Résumé : International audience
Here, the first description of an epsilon sulfur-oxidizing bacterium from sulfide-rich sediments of marine mangrove in Caribbean is reported. According to TEM, this new strain contains intracytoplasmic large internal sulfur granules as confirmed by EDXS analyses performed using ESEM. The sulfur distribution obtained for this sulfur-oxidizing bacterial strain allows to conclude that elemental sulfur is formed as an intermediate oxidation product and stored intracellularly. According to conventional SEM observations, bacterial cells are ovoid, extremely motile by lophotrichous flagella. Phylogenetic analyses based on the analysis of partial sequence of 16S rDNA confirm that such bacterial strain belongs to the Thiovulum cluster and could be a representative of a new species in this poorly studied genus of sulfur-oxidizing free-living bacteria. Thus, reduced sediment of marine mangrove represents sulfide-rich environment sustaining development of both gamma and epsilon sulfur-oxidizing Proteobacteria
ISSN: 0378-1097

hal-01682113
https://hal.univ-antilles.fr/hal-01682113
DOI : 10.1093/femsle/fnx172

Éditeur(s) : HAL CCSD
Résumé : International audience
Spermatogenesis is a highly sophisticated process involved in the transmission of genetic heritage. It includes halving ploidy, repackaging of the chromatin for transport, and the equipment of developing spermatids and eventually spermatozoa with the advanced apparatus (e.g., tightly packed mitochondrial sheat in the mid piece, elongating of the tail, reduction of cytoplasmic volume) to elicit motility once they reach the epididymis. Mammalian spermatogenesis is divided into three phases. In the first the primitive germ cells or spermatogonia undergo a series of mitotic divisions. In the second the spermatocytes undergo two consecutive divisions in meiosis to produce haploid spermatids. In the third the spermatids differentiate into spermatozoa in a process called spermiogenesis. Paracrine, autocrine, juxtacrine, and endocrine pathways all contribute to the regulation of the process. The array of structural elements and chemical factors modulating somatic and germ cell activity is such that the network linking the various cellular activities during spermatogenesis is unimaginably complex. Over the past two decades, advances in genomics have greatly improved our knowledge of spermatogenesis, by identifying numerous genes essential for the development of functional male gametes. Large-scale analyses of testicular function have deepened our insight into normal and pathological spermatogenesis. Progress in genome sequencing and microarray technology have been exploited for genome-wide expression studies, leading to the identification of hundreds of genes differentially expressed within the testis. However, although proteomics has now come of age, the proteomics-based investigation of spermatogenesis remains in its infancy. Here, we review the state-of-the-art of large-scale proteomic analyses of spermatogenesis, from germ cell development during sex determination to spermatogenesis in the adult. Indeed, a few laboratories have undertaken differential protein profiling expression studies and/or systematic analyses of testicular proteomes in entire organs or isolated cells from various species. We consider the pros and cons of proteomics for studying the testicular germ cell gene expression program. Finally, we address the use of protein datasets, through integrative genomics (i.e., combining genomics, transcriptomics, and proteomics), bioinformatics, and modelling.
Systems Biology in Reproductive Medicine

hal-00877749
https://hal.archives-ouvertes.fr/hal-00877749
DOI : 10.3109/19396368.2012.691943
PUBMED : 22788530

Éditeur(s) : Université des Antilles Études caribéennes
Résumé : Loin d’être un phénomène nouveau, les mobilités internationales se sont fortement accrues depuis les années 1960. Aujourd’hui, le contexte de mondialisation tend à accélérer les dynamiques migratoires alors que dans le même temps s’observe une élévation des niveaux d’éducation. Ainsi, la soutenabilité de l’augmentation de la fuite des cerveaux dans le monde soulève interrogations et réflexions.Le poids des flux de migrants qualifiés allié à la fragilité relative des données, pose la nécessité d’aborder en profondeur le problème de la fuite des cerveaux. Une analyse au cas par cas s’impose. À partir de données se rapportant à la diaspora caribéenne sur la base statistique de Docquier et Marfouk, cet article propose une réflexion sur les facteurs explicatifs de la fuite des cerveaux dans les territoires insulaires caribéens.
Far from being a new phenomenon, the international motilities have increased since the 60’s. Today, the context of globalization tends to accelerate the migratory dynamics while at the same time observed a rise of the educational levels. The increase of the brain drain has respite to many questions.Nevertheless, image, nature of flows of skilled migrants combined with relative data’s fragility and the necessity to approach the problem and presenting appropriate policies, impose an analysis case by case. Using data relating to the Caribbean diaspora on the statistical basis of Docquier and Marfouk, this article purpose a reflection on the factors that explain the brain drain in the Caribbean islands.
Caraïbes

Droits : info:eu-repo/semantics/openAccess
urn:doi:10.4000/etudescaribeennes.4702
http://journals.openedition.org/etudescaribeennes/4702

Éditeur(s) : HAL CCSD BioMed Central
Résumé : International audience
BACKGROUND: The orphan receptors COUP-TF (chicken ovalbumin upstream promoter transcription factor) I and II are members of the nuclear receptor superfamily that play distinct and critical roles in vertebrate organogenesis. The involvement of COUP-TFs in cancer development has recently been suggested by several studies but remains poorly understood. METHODS: MCF-7 breast cancer cells overexpressing COUP-TFI and human breast tumors were used to investigate the role of COUP-TFI in the regulation of CXCL12/CXCR4 signaling axis in relation to cell growth and migration. We used Immunofluorescence, western-blot, RT-PCR, Formaldehyde-assisted Isolation of Regulatory Elements (FAIRE) assays, as well as cell proliferation and migration assays. RESULTS: Previously, we showed that COUP-TFI expression is enhanced in breast cancer compared to normal tissue. Here, we report that the CXCL12/CXCR4 signaling pathway, a crucial pathway in cell growth and migration, is an endogenous target of COUP-TFI in breast cancer cells. The overexpression of COUP-TFI in MCF-7 cells inhibits the expression of the chemokine CXCL12 and markedly enhances the expression of its receptor, CXCR4. Our results demonstrate that the modification of CXCL12/CXCR4 expression by COUP-TFI is mediated by the activation of epithelial growth factor (EGF) and the EGF receptor. Furthermore, we provide evidence that these effects of COUP-TFI increase the growth and motility of MCF-7 cells in response to CXCL12. Cell migration toward a CXCL12 gradient was inhibited by AMD3100, a specific antagonist of CXCR4, or in the presence of excess CXCL12 in the cell culture medium. The expression profiles of CXCR4, CXCR7, CXCL12, and COUP-TFI mRNA in 82 breast tumors and control non-tumor samples were measured using real-time PCR. CXCR4 expression was found to be significantly increased in the tumors and correlated with the tumor grade, whereas the expression of CXCL12 was significantly decreased in the tumors compared with the healthy samples. Significantly higher COUP-TFI mRNA expression was also detected in grade 1 tumors. CONCLUSIONS: Together, our mechanistic in vitro assays and in vivo results suggest that a reduction in chemokine CXCL12 expression, with an enhancement of CXCR4 expression, provoked by COUP-TFI, could be associated with an increase in the invasive potential of breast cancer cells.
ISSN: 1471-2407

hal-01024753
https://hal-univ-rennes1.archives-ouvertes.fr/hal-01024753
https://hal-univ-rennes1.archives-ouvertes.fr/hal-01024753/document
https://hal-univ-rennes1.archives-ouvertes.fr/hal-01024753/file/1471-2407-14-407.pdf
DOI : 10.1186/1471-2407-14-407

Éditeur(s) : HAL CCSD Station Biologique
Résumé : International audience
The embryonic development of Tivela mactroides, from fertilization to straight-hinge veliger D-stage larva occurs in 18 hours at 25°C. Scanning electronic observations show that morphogenetic processes result in a gastrula with two depressions 4 hours after fertilization (T0 + 4h). Two hours later, one depression, located at the animal pole, develops into an open cave, the floor of which becomes the shell field located below the lower face of the prototrochal pad. The invagination located at the vegetal pole features the blastopore. At T0 + 6h, the late gastrula has differentiated into a typical motile trochophore with a shell field synthetizing the organic part of the shell. At T0 + 8h, the shell field, located between the prototroch and the telotroch, appears as a saddle-shaped region with a wrinkled surface extending on both sides of the embryo, establishing bilateral symmetry. At T0 + 12h, the prototroch slides toward the anterior region by outgrowth of the shell material. At T0 + 18h, the prodissoconch I formation is completed and the D-stage larvae possess a calcified shell. At this stage of development, the functional velum is composed of four bands of cilia. Our observations seem to confirm the interpretation of shell differentiation proposed recently by Mouëza et al. (2006) for bivalves even if Transmission Electronic observations will be necessary to validate definitively such a model in the Meretricinae sub-family.
ISSN: 0007-9723

hal-00753022
https://hal.univ-antilles.fr/hal-00753022

Éditeur(s) : HAL CCSD Wiley
Résumé : International audience
The embryonic development in Chione cancellata, from fertilization to straighthinge D-stage veliger larva, occurs in 24 h at 251C. Transmission (TEM) and scanning (SEM) electron microscopy show that morphogenetic processes result in a gastrula with two depressions, 4 h after fertilization (T014 h). Two hours later, one depression, located at the animal pole, develops into an open cave, the floor of which becomes the shell field, characterized by scarce microvilli, located below the lower face of the prototrochal pad. The invagination located at the vegetal pole is characterized by regular microvilli and constitutes the digestive tract. At T018 h, the late gastrula differentiates into a typical motile trochophore, possessing a well-developed prototroch delimiting anterior and posterior embryonic regions. At T019h, the shell field, located between the prototroch and the telotroch, appears as a saddle-shaped region with a wrinkled surface extending on both sides of the embryo, establishing bilateral symmetry. From TEM observations, the apical surface of the underlying cells possesses a modified glycocalyx featuring a dense pellicle overlapping the cells of the shell field. At T0112 h, the prototroch is displaced toward the anterior region by outgrowth of the shell material. TEM views show that the wrinkled surface observed with SEM corresponds to the periostracum, attached dorsally to the hinge and ventrally to the cells of the future mantle edge. At T0115 h, an alveolar matrix of proteinaceous material, which could contain calcite crystals, appears between the periostracum and the mantle. At T0124 h, prodissoconch I formation is completed and the D-stage larvae possess a calcified shell. At this stage of development, only one mantle fold is present, representing the outer fold. The periostracumsecreting cells are in contact with the marginal cells of the velum. This functional velum is composed of four bands of cilia. Our TEMobservations confirm previous descriptions of the velum ciliary bands obtained only from SEM analyses, such as described in other bivalves. The apical sense organ and the digestive tract are poorly developed. From observations at the ultrastructural level of shell differentiation in C. cancellata, we propose a new interpretation of shell differentiation, including hinge and ligament for bivalves as opposed to that described for gastropods.
ISSN: 1077-8306

hal-00755283
https://hal.univ-antilles.fr/hal-00755283
DOI : 10.1111/j.1744-7410.2006.00036.x