Éditeur(s) : HAL CCSD Springer Verlag
Résumé : International audience
In this work, we have studied quenching of the fluorescence of two well-known oxygen probes, 1-pyrene butyric acid (PBA) and tris(2,2'-bipyridine)ruthenium ([Ru(bpy)(3)](2+)) by reactive oxygen species (superoxide anion, nitric oxide derivative, hydrogen peroxide) and by the O(2) molecule. Both, time-resolved and steady state fluorescence measurements were performed in solution (ethanol, dimethyl sufoxide, water) and in micelles of Sodium Dodecyl Sulfate that serve as a model for membrane-containing biological structures. We have found that only the free radicals and O(2) can actively quench for the two probes, but not the diamagnetic H(2)O(2). Our data correspond to the classical Stern-Volmer equation. H(2)O(2) has an effect only at high molar concentrations (>0.1 M). In contrast, effective concentrations of free radicals and O(2) that lead to quenching are in millimolar range. In conclusion, our methods allows for detecting global ROS that are small free radicals without interference from the reactive hydroxyl radical. Our data suggest that the method can be used for the quantification of ROS in individual living cells based on the measurement of fluorescence lifetime of those probes
ISSN: 1053-0509

hal-01326234
https://hal.archives-ouvertes.fr/hal-01326234
DOI : 10.1007/s10895-008-0425-z

Éditeur(s) : HAL CCSD BioScientifica
Résumé : International audience
The general rules established from mammalian species for the regulation of spermatogenesis by gonadotropins may not be fully relevant in fish. Particularly, Fsh is as potent as Lh to stimulate steroidogenesis and the Fsh receptor is expressed in Leydig cells. In seasonal breeders, Fsh is likely the major gonadotropin involved in spermatogenesis onset and Lh is required to support spermatogenesis progression and gamete release. However, the genes that relay the action of Fsh and Lh have been poorly investigated in fish. The present study was aimed at identifying gonadotropin-dependent genes expressed in the testis during fish puberty. We cultured pubertal trout testicular explants for 96 h, with or without gonadotropin, and analyzed transcriptome variations using microarrays. Fsh and Lh had similar effects on a large group of genes while other genes were preferentially regulated by one or the other gonadotropin. We showed that most of the responsive genes were expressed in somatic cells and exhibited relevant patterns during the seasonal reproductive cycle. Some genes preferentially modulated by Lh could be involved in testicular cell fate (pvrl1 and bty) or sperm maturation (ehmt2 and racgap1) and will deserve further examination. Besides Fsh's effects on the steroidogenic pathway, our study demonstrates that Fsh coordinates relevant stimulatory and inhibitory paracrine factors known to regulate early germ cell proliferation and differentiation. Some of these genes belong to major regulatory pathways including the Igf pathway (igf1b/igf3 and igfbp6), the Tgfb pathway (amh, inha, inhba, and fstl3), the Wnt pathway (wisp1), and pleiotrophin (mdka).
ISSN: 0952-5041

inserm-00812401
http://www.hal.inserm.fr/inserm-00812401
DOI : 10.1530/JME-12-0197
PUBMED : 23045716

Éditeur(s) : HAL CCSD Springer Verlag
Résumé : International audience
Interleukin-27 (IL-27) belongs to the IL-6/IL-12 family of cytokines, associated with different inflammatory diseases and orchestrates its biological activity via common heterodimeric receptor composed of WSX-1 (IL-27Rα) and gp130. The present study was aimed to investigate the regulation of CXCL9, CXCL10, and CXCL11 chemokines in hepatic cells (human LX-2 cell line derived from normal human stellate cells (HSC), primary human hepatocytes, HSC, and HepG2 cells) and concanavalin A (ConA)-induced liver inflammation. We demonstrated that IL-27, but not IL-6, induced/up-regulated CXCR3 ligand genes (CXCL9, CXCL10, and CXCL11; out of 26 selected genes) in a STAT1-dependent manner in hepatic cells in vitro both at transcript and protein levels. In ConA-induced T cell-mediated hepatic model, we showed that soluble IL-27/IFNγ was elevated following ConA hepatitis in association with increased CXCL9, CXCL10, and CXCL11 expression in the liver. The exogenous IL-27 administration induced CXCR3 ligands in mouse liver at 4 h with any significant effect on recruitment of CXCR3(+) immune cells in the liver. The neutralization of IL-27 during ConA hepatitis differentially modulated (transcript vs protein expression) CXCR3 ligands and IFNγ during ConA-induced hepatitis with down-regulated expression of CXCL9 and CXCL10 at transcript level. The IFNγ, complementary regulated the expression of CXCR3 ligands as their up-regulation during ConA hepatitis, was abolished in IFNγ KO mice. In summary, IL-27 up-regulated the CXCL9, CXCL10, and CXCL11 chemokine expression in hepatic cells. IL-27 regulated CXCR3 ligand expression in IFNγ-dependent manner during acute hepatitis suggesting a complementary role of IL-27 and IFNγ to moderate liver inflammation via regulation of CXCR3 ligands. KEY MESSAGE: IL-27 up-regulated CXCR3 ligand expression in human hepatic cells in vitro. IL-27 up-regulated CXCR3 ligand expression and secretion in ConA hepatitis in vivo. CXCR3 ligand expression was down-regulated by blocking IL-27 or IFNγ deficiency. IL-27 modulated liver injury by regulation of CXCR3 ligands in IFNγ-dependent manner.
ISSN: 0946-2716

hal-01214006
https://hal-univ-rennes1.archives-ouvertes.fr/hal-01214006
DOI : 10.1007/s00109-015-1319-6
PUBMED : 26199110

Éditeur(s) : HAL CCSD Wiley
Résumé : The extent of gene dispersal is a fundamental factor of the population and evolutionary dynamics of tropical tree species, but directly monitoring seed and pollen movement is a difficult task. However, indirect estimates of historical gene dispersal can be obtained from the fine-scale spatial genetic structure of populations at drift-dispersal equilibrium. Using an approach that is based on the slope of the regression of pairwise kinship coefficients on spatial distance and estimates of the effective population density, we compare indirect gene dispersal estimates of sympatric populations of 10 tropical tree species. We re-analysed 26 data sets consisting of mapped allozyme, SSR (simple sequence repeat), RAPD (random amplified polymorphic DNA) or AFLP (amplified fragment length polymorphism) genotypes from two rainforest sites in French Guiana. Gene dispersal estimates were obtained for at least one marker in each species, although the estimation procedure failed under insufficient marker polymorphism, limited sample size, or inappropriate sampling area. Estimates generally suffered low precision and were affected by assumptions regarding the effective population density. Averaging estimates over data sets, the extent of gene dispersal ranged from 150 m to 1200 m according to species. Smaller gene dispersal estimates were obtained in species with heavy diaspores, which are presumably not well dispersed, and in populations with high local adult density. We suggest that limited seed dispersal could indirectly limit effective pollen dispersal by creating higher local tree densities, thereby increasing the positive correlation between pollen and seed dispersal distances. We discuss the potential and limitations of our indirect estimation procedure and suggest guidelines for future studies
ISSN: 0962-1083

hal-01031603
https://hal.archives-ouvertes.fr/hal-01031603
DOI : 10.1111/j.1365-294X.2005.02785.x

Éditeur(s) : HAL CCSD Public Library of Science
Résumé : International audience
Staphylococcus aureus is a highly versatile, opportunistic pathogen and the etiological agent of a wide range of infections in humans and warm-blooded animals. The epithelial surface is its principal site of colonization and infection. In this work, we investigated the cytopathic effect of S. aureus strains from human and animal origins and their ability to affect the host cell cycle in human HeLa and bovine MAC-T epithelial cell lines. S. aureus invasion slowed down cell proliferation and induced a cytopathic effect, resulting in the enlargement of host cells. A dramatic decrease in the number of mitotic cells was observed in the infected cultures. Flow cytometry analysis revealed an S. aureus-induced delay in the G2/M phase transition in synchronous HeLa cells. This delay required the presence of live S. aureus since the addition of the heat-killed bacteria did not alter the cell cycle. The results of Western blot experiments showed that the G2/M transition delay was associated with the accumulation of inactive cyclin-dependent kinase Cdk1, a key inducer of mitosis entry, and with the accumulation of unphosphorylated histone H3, which was correlated with a reduction of the mitotic cell number. Analysis of S. aureus proliferation in asynchronous, G1- and G2-phase-enriched HeLa cells showed that the G2 phase was preferential for bacterial infective efficiency, suggesting that the G2 phase delay may be used by S. aureus for propagation within the host. Taken together, our results divulge the potential of S. aureus in the subversion of key cellular processes such as cell cycle progression, and shed light on the biological significance of S. aureus-induced host cell cycle alteration.
ISSN: 1932-6203

hal-00873672
https://hal.archives-ouvertes.fr/hal-00873672
https://hal.archives-ouvertes.fr/hal-00873672/document
https://hal.archives-ouvertes.fr/hal-00873672/file/Staphylococcus_aureus-Induced.accepted.pdf
DOI : 10.1371/journal.pone.0063279

Éditeur(s) : Elsevier Science Bv
Résumé : The main objective of this work was to establish the influence of sex, maturity and reproduction on the contamination of the demersal fish Merluccius merluccius by organochlorine compounds. Polychlorinated biphenyls (PCBs) and p,p'DDE were quantified in muscle, liver and gonads of female and male hakes collected in the Gulf of Lions in 2004 and 2005. Observed levels appeared higher than the population of the Bay of Biscay and lower than the population of the Thyrrenian Sea. Contaminant fingerprints were roughly constant whatever the studied organ and the hake biological condition. Concentrations varied significantly according to the sex and maturity of hakes. Mature specimens were more contaminated than immature, and males presented higher levels than females. This sex effect can be linked to a lower growth rate of males, and a contaminant elimination during female spawning. Gonadal contamination depends on the importance of lipid content and increases with the maturation degree. Although the main organ of energy and PCB storage is the liver, muscle appears as the main contributor to the gonad contamination. (C) 2009 Elsevier B.V. All rights reserved.
Science Of The Total Environment (0048-9697) (Elsevier Science Bv), 2009-12 , Vol. 408 , N. 2 , P. 304-311

Droits : 2009 Elsevier B.V. All rights reserved.
http://archimer.ifremer.fr/doc/00000/11129/9317.pdf
DOI:10.1016/j.scitotenv.2009.10.004
http://archimer.ifremer.fr/doc/00000/11129/

Éditeur(s) : HAL CCSD Nature Publishing Group
Résumé : International audience
Most tumors undergo metabolic reprogramming towards glycolysis, the so-called Warburg effect, to support growth and survival. Overexpression of IF1, the physiological inhibitor of the F0F1ATPase, has been related to this phenomenon and appears to be a relevant marker in cancer. Environmental contributions to cancer development are now widely accepted but little is known about the underlying intracellular mechanisms. Among the environmental pollutants humans are commonly exposed to, benzo[a]pyrene (B[a]P), the prototype molecule of polycyclic aromatic hydrocarbons (PAHs), is a well-known human carcinogen. Besides apoptotic signals, B[a]P can also induce survival signals in liver cells, both likely involved in cancer promotion. Our previous works showed that B[a]P elicited a Warburg-like effect, thus favoring cell survival. The present study aimed at further elucidating the molecular mechanisms involved in the B[a]P-induced metabolic reprogramming, by testing the possible involvement of IF1. We presently demonstrate, both in vitro and in vivo, that PAHs, especially B[a]P, strongly increase IF1 expression. Such an increase, which might rely on β2-adrenergic receptor activation, notably participates to the B[a]P-induced glycolytic shift and cell survival in liver cells. By identifying IF1 as a target of PAHs, this study provides new insights about how environmental factors may contribute to related carcinogenesis.
ISSN: 2045-2322

hal-01518808
https://hal-univ-rennes1.archives-ouvertes.fr/hal-01518808
https://hal-univ-rennes1.archives-ouvertes.fr/hal-01518808/document
https://hal-univ-rennes1.archives-ouvertes.fr/hal-01518808/file/Hardonni%C3%A8re%20et%20al%202017.pdf
DOI : 10.1038/s41598-017-00269-7

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
Viral haemorragic fevers are characterized by similar clinical manifestations, with a biphasic course : After a 2-21 day-incubation, onset of an influenza-like illness, that will drive to an haemorragic syndrom with shock, in a subgroup of patients, unpredictable. Human-to-human transmission mostly occurs through contact with biological fluids, especially if contaminated with blood. The biology, the epidemiology and the letality of these viruses differ. For all these viral haemorragic fevers, the importance of an early diagnosis relies mostly in the need to interrupt human-to-human transmission, as therapeutic options are mostly restricted to symptomatic treatment, with the exception of Lassa fever (ribavirin probably effective).
Les fièvres hémorragiques virales regroupent plusieurs viroses, potentiellement graves, avec un tableau clinique relativement stéréotypé, d’évolution biphasique. Après une incubation de 2 à 21 jours, apparition d’un syndrome pseudo-grippal qui évolue au bout de quelques jours, de manière imprévisible, chez une proportion variable de patients, vers un syndrome hémorragique avec choc. La transmission interhumaine s’effectue le plus souvent par contacts avec des liquides biologiques, surtout en présence de sang. La biologie de ces virus, leur épidémiologie et leur létalité sont très variables. Pour toutes ces fièvres hémorragiques virales, l’importance d’un diagnostic rapide réside plus dans la nécessité d’interrompre les chaînes de transmission que dans les possibilités thérapeutiques, limitées aux traitements symptomatiques, à l’exception notable de la fièvre de Lassa (efficacité probable de la ribavirine).
ISSN: 1773-035X

hal-01299296
https://hal-univ-rennes1.archives-ouvertes.fr/hal-01299296
https://hal-univ-rennes1.archives-ouvertes.fr/hal-01299296/document
https://hal-univ-rennes1.archives-ouvertes.fr/hal-01299296/file/Fi%C3%A8vres%20h%C3%A9morragiques%20virales_accepted.pdf
DOI : 10.1016/S1773-035X(16)30091-0

Éditeur(s) : HAL CCSD PeerJ
Résumé : International audience
Understanding the role of predators in food webs can be challenging in highly diverse predator/prey systems composed of small cryptic species. DNA based dietary analysis can supplement predator removal experiments and provide high resolution for prey identification. Here we use a metabarcoding approach to provide initial insights into the diet and functional role of coral-dwelling predatory fish feeding on small invertebrates. Fish were collected in Moorea (French Polynesia) where the BIOCODE project has generated DNA barcodes for numerous coral associated invertebrate species. Pyrosequencing data revealed a total of 292 Operational Taxonomic Units (OTU) in the gut contents of the arc-eye hawkfish (Paracirrhites arcatus), the flame hawkfish (Neocirrhites armatus) and the coral croucher (Caracanthus maculatus). One hundred forty-nine (51%) of them had species-level matches in reference libraries (>98% similarity) while 76 additional OTUs (26%) could be identified to higher taxonomic levels. Decapods that have a mutualistic relationship with Pocillopora and are typically dominant among coral branches, represent a minor contribution of the predators' diets. Instead, predators mainly consumed transient species including pelagic taxa such as copepods, chaetognaths and siphonophores suggesting non random feeding behavior. We also identified prey species known to have direct negative interactions with stony corals, such as Hapalocarcinus sp, a gall crab considered a coral parasite, as well as species of vermetid snails known for their deleterious effects on coral growth. Pocillopora DNA accounted for 20.8% and 20.1% of total number of sequences in the guts of the flame hawkfish and coral croucher but it was not detected in the guts of the arc-eye hawkfish. Comparison of diets among the three fishes demonstrates remarkable partitioning with nearly 80% of prey items consumed by only one predator. Overall, the taxonomic resolution provided by the metabarcoding approach highlights a highly complex interaction web and demonstrates that levels of trophic partitioning among coral reef fishes have likely been underestimated. Therefore, we strongly encourage further empirical approaches to dietary studies prior to making assumptions of trophic equivalency in food web reconstruction. How to cite this article Leray et al. (2015), Metabarcoding dietary analysis of coral dwelling predatory fish demonstrates the minor contribution of coral mutualists to their highly partitioned, generalist diet. PeerJ 3:e1047
ISSN: 2167-8359

Droits : http://creativecommons.org/licenses/by/
hal-01174184
https://hal-univ-perp.archives-ouvertes.fr/hal-01174184
https://hal-univ-perp.archives-ouvertes.fr/hal-01174184/document
https://hal-univ-perp.archives-ouvertes.fr/hal-01174184/file/peerj-1047.pdf
DOI : 10.7717/peerj.1047

Éditeur(s) : HAL CCSD Wiley
Résumé : International audience
Recent reports suggest that extracellular signal-regulated kinase (ERK1) and ERK2 mitogen-activated protein kinases (MAPK) may direct specific biological functions under certain contexts. In this study, we investigated the role of early and sustained epidermal growth factor (EGF) stimulation on long-term hepatocyte differentiation and the possible role of ERK1 and ERK2 in this process. We demonstrate a long-term survival and an elevated level of differentiation up to 3 weeks. The differentiation state of hepatocytes is supported by sustained expression of aldolase B, albumin, and the detoxifying enzymes CYP1A2, 2B2, and 3A23. Similarly to freshly isolated cells, cultured hepatocytes also retain the ability to respond to 3-methylcholanthrene (3MC) and phenobarbital (PB), two known CYP inducers. In addition, we show evidence that continuous MAPK/ERK kinase (MEK) inhibition enhances the level of differentiation. Using RNA interference approaches against ERK1 and ERK2, we demonstrate that this effect requires both ERK1 and ERK2 activity, whereas the specific ERK1 knockdown promotes cell survival and the specific ERK2 knockdown regulates cell proliferation. In conclusion, we demonstrate that early and sustained EGF stimulation greatly extends long-term hepatocyte survival and differentiation, and that inhibition of the ERK1/2 MAPK pathway potentiates these pro-survival/pro-differentiation phenotypes. We clearly attest that specific ERK1 and ERK2 MAPKs determine hepatocyte survival and proliferation, respectively, whereas dual inhibition is required to stabilize a highly differentiated state.
ISSN: 0021-9541

hal-00681056
https://hal.archives-ouvertes.fr/hal-00681056
DOI : 10.1002/jcp.22742
PUBMED : 21437905

Éditeur(s) : ISTPM
Résumé : Table of Contents The Natural Environment Production centres Oyster farming centres Mussel farming centres Chapter I. - The Physicochemical Environment I. Sea Water a) Transparency, turbidity b) Temperature c) Salinity d) Dissolved gases e) Substances dissolved in the water f) Water movements g) Hydrology of the main shellfish farming centres II. Soils a) Soil properties b) Mechanical amendment of soils, its effects c) Fertilisation of soils in shellfish farming d) Changes in soils due to farming Bibliography Chapter II. - The Natural Environment Phytoplankton Zooplankton Basic biology of phytoplankton Assessment of phytoplankton production, notion of primary productivity Phytoplankton from a few shellfish farming regions Microphytobenthos Factors controlling primary productivity Toxicity of planktonic organisms; red tides Bibliography Chapter III – Alterations in the Natural Environment Pollution I. Chemical Pollution Definitions Influence of turbidity A. Telluric pollution 1o Domestic pollution 2o Agriculture-related pollution 3o Industrial pollution B. Pelagic pollution 1o Pollution through hydrocarbons Conclusion II. Bacterial Pollution Future of micro-organisms in the sea A. Specimen conditions B. Phenomena of dispersion Survival of germs in the marine environment A. Factors influencing the total microbial content B. Resistance of various groups of germs Consequences of bacterial pollutions on shellfish and shellfish farming Shellfish Shellfish farming Conclusion Bibliography
Sommaire : Le milieu naturel Les centres de production Les centres ostréicoles Les centres mytilicoles Chapitre I. - le milieu physico-chimique I. L'eau de mer a) Transparence, turbidité b) Température c) Salinité d ) Les gaz dissous e) Les substances dissoutes dans l'eau f) Les mouvements de l'eau g) Hydrologie des principaux centres conchylicoles IL Les sols a ) Propriétés des sols b) Amendement mécanique des sols, ses effets c) La fertilisation des sols en conchylicutture d) Evolution des sols du fait de la culture Bibliographie Chapitre II. - le milieu biologique Le phytoplancton Le zooplancton Biologie sommaire du phytoplancton Evaluation de la production de phytoplancton, notion de productivité primaire Phytoplancton de quelques régions conchylicoles Le microphytobenthos Facteurs contrôlant la productivité primaire Toxicité d'organismes planctoniques ; les eaux rouges bibliographie Chapitre III - les altérations du milieu naturel. Les pollutions I. Les pollutions chimiques Définitions Influence de la turbidité A. Pollution tellurique 1° Pollution d'origine domestique 2° Pollutions liées aux activités agricoles 3° Pollutions industrielles B. Pollution pélagique 1° Pollution par les hydrocarbures Conclusion II. Les pollutions bactériennes Devenir des microorganismes dans la mer A. Conditions de prélèvements B. Phénomènes de dispersion Survie des germes dans le milieu marin A. Facteurs influant sur la teneur microbienne globale B. Résistance des divers groupes de germes Conséquences des pollutions bactériennes sur les coquillages et sur la conchyliculture Les coquillages La conchyliculture Conclusion Bibliographie
Revue des Travaux de l'Institut des Pêches Maritimes (0035-2276) (ISTPM), 1974-09 , Vol. 38 , N. 3 , P. 217-337

Droits : Ifremer
http://archimer.ifremer.fr/doc/1974/publication-1776.pdf
http://archimer.ifremer.fr/doc/00000/1776/

Éditeur(s) : HAL CCSD Wiley
Résumé : International audience
BACKGROUND:Sickle cell anaemia (SCA) is a severe hereditary haemoglobinopathy characterised by haemorheological abnormalities, which play a role in the occurrence of several acute and chronic clinical complications. While βS -haplotypes and alpha-thalassaemia modulate SCA clinical severity, their effects on blood rheology have been incompletely described. The aim of this study was to test the effects of these genetic modifiers on the haemorheological properties and clinical complication of children with SCA.PROCEDURE:Steady-state haemorheological profile, biological parameters, βS -haplotypes, alpha-globin status, vaso-occlusive crisis (VOC) and acute chest syndrome frequencies were analysed in 128 children (aged 5 to 18 years) with SCA.RESULTS:Patients with alpha-thalassaemia showed increased red blood cell (RBC) deformability and aggregation compared to those without. Median VOC rate was higher in patients with homozygous alpha-thalassaemia compared to those with a normal alpha genotype. Conversely, the haemorheological profile and clinical complications were not influenced by the βS -haplotypes in our study.CONCLUSION:Our results demonstrate that alpha-thalassaemia is associated with higher risk for VOC events in children with SCA, which may be due in part to its effects on RBC deformability and aggregation.
ISSN: 1545-5009

hal-01668317
https://hal.univ-antilles.fr/hal-01668317
DOI : 10.1002/pbc.26455
PUBMED : 28097791

Éditeur(s) : HAL CCSD BioMed Central
Résumé : International audience
ABSTRACT: Environmental exposures during pregnancy and early life may have adverse health effects. Single birth cohort studies often lack statistical power to tease out such effects reliably. To improve the use of existing data and to facilitate collaboration among these studies, an inventory of the environmental exposure and health data in these studies was made as part of the ENRIECO (Environmental Health Risks in European Birth Cohorts) project. The focus with regard to exposure was on outdoor air pollution, water contamination, allergens and biological organisms, metals, pesticides, smoking and second hand tobacco smoke (SHS), persistent organic pollutants (POPs), noise, radiation, and occupational exposures. The review lists methods and data on environmental exposures in 37 European birth cohort studies. Most data is currently available for smoking and SHS (N=37 cohorts), occupational exposures (N=33), outdoor air pollution, and allergens and microbial agents (N=27). Exposure modeling is increasingly used for long-term air pollution exposure assessment; biomonitoring is used for assessment of exposure to metals, POPs and other chemicals; and environmental monitoring for house dust mite exposure assessment. Collaborative analyses with data from several birth cohorts have already been performed successfully for outdoor air pollution, water contamination, allergens, biological contaminants, molds, POPs and SHS. Key success factors for collaborative analyses are common definitions of main exposure and health variables. Our review emphasizes that such common definitions need ideally be arrived at in the study design phase. However, careful comparison of methods used in existing studies also offers excellent opportunities for collaborative analyses. Investigators can use this review to evaluate the potential for future collaborative analyses with respect to data availability and methods used in the different cohorts and to identify potential partners for a specific research question.
ISSN: 1476-069X

inserm-00785248
http://www.hal.inserm.fr/inserm-00785248
http://www.hal.inserm.fr/inserm-00785248/document
http://www.hal.inserm.fr/inserm-00785248/file/1476-069X-12-8.pdf
DOI : 10.1186/1476-069X-12-8

Éditeur(s) : HAL CCSD Kluwer Academic Publishers
Résumé : International audience
The interlocking leaves of tank-forming bromeliads (Bromeliaceae) collect rainwater and detritus, thus creating a freshwater habitat for specialized organisms. Their abundance and the possibility of quantifying communities with accuracy give us unparalleled insight into how changes in local to regional environments influence community diversity in small water bodies. We sampled 365 bromeliads (365 invertebrate communities) along a southeastern to northwestern range in French Guiana. Geographic locality determined the species pool for bromeliad invertebrates, and local environments determined the abundance patterns through the selection of traits that are best adapted to the bromeliad habitats. Patterns in community structure mostly emerged from patterns of predator species occurrence and abundance across local-regional environments, while the set of detritivores remained constant. Water volume had a strong positive correlation with invertebrate diversity, making it a biologically relevant measure of the pools' carrying capacity. The significant effects of incoming detritus and incident light show that changes in local environments (e.g., the conversion of forest to cropping systems) strongly influence freshwater communities. Because changes in local environments do not affect detritivores and predators equally, one may expect functional shifts as sets of invertebrates with particular traits are replaced or complemented by other sets with different traits.
Hydrobiologia

hal-00845572
https://hal.archives-ouvertes.fr/hal-00845572

Éditeur(s) : HAL CCSD Linnean Society of London
Résumé : Disentangling the impact of landscape features such as rivers and historical events on dispersal is a challenging but necessary task to gain a comprehensive picture of the evolution of diverse biota such as that found in Amazonia. Adenomera andreae, a small, territorial, terrestrial frog species of the Amazonian forest represents a good model for such studies. We combined cytochrome b sequences with 12 microsatellites to investigate the genetic structure at two contrasted spatial scales in French Guiana: along a similar to 6-km transect, to evaluate dispersal ability, and between paired bank populations along a similar to 65-km stretch of the Approuague river, to test the effect of rivers as barriers to dispersal. We observed significant spatial genetic structure between individuals at a remarkably small geographical scale, and conclude that the species has a restricted dispersal ability that is probably tied to its life-history traits. Mitochondrial and microsatellite data also indicate a high level of differentiation among populations on opposite banks of the river, and, in some cases, among populations on the same riverbank. These results suggest that the observed population structure in A. andreae is the result of restricted dispersal abilities combined with the action of rivers and Quaternary population isolation. Given that Amazonia hosts a great portion of anurans, as well as other small vertebrates, that display life-history traits comparable with A. andreae, we argue that our analyses provide new insights into the complex interactions among evolutionary processes shaping Amazonian biodiversity. (c) 2012 The Linnean Society of London, Biological Journal of the Linnean Society, 2012, 106, 356373.
ISSN: 0024-4066

hal-01032422
https://hal.archives-ouvertes.fr/hal-01032422
DOI : 10.1111/j.1095-8312.2012.01871.x

Éditeur(s) : HAL CCSD Wiley
Résumé : International audience
With the growing use of selective serotonin reuptake inhibitor medications (SSRIs) for the treatment of depression during the perinatal period, questions have been raised about the longterm impact of these medications on development. We aimed to investigate how developmental SSRI exposure may alter affect-related behaviors and associated molecular processes in offspring using a rodent model of maternal stress and depression. For this purpose, prenatally stressed or non-stressed male offspring were exposed to fluoxetine (5 mg/kg/day) or vehicle, via lactation, until weaning. Primary results show that postnatal fluoxetine exposure differentially altered anxiety-like behavior by increasing anxiety in non-stressed offspring and decreasing anxiety in prenatally stressed offspring. In the hippocampus, developmental fluoxetine exposure decreased BDNF IV and TrkB mRNA expression. Prenatal stress alone also decreased escape behaviors and decreased hippocampal BDNF IV mRNA expression. These data provide important evidence for the long-term programming effects of early-life exposure to SSRIs on brain and behavior.
ISSN: 0012-1630

hal-01305478
https://hal-univ-rennes1.archives-ouvertes.fr/hal-01305478
https://hal-univ-rennes1.archives-ouvertes.fr/hal-01305478/document
https://hal-univ-rennes1.archives-ouvertes.fr/hal-01305478/file/Developmental%20SSRIs%2C%20anxiety%20and%20BDNF_accepted.pdf
DOI : 10.1002/dev.21385

Éditeur(s) : HAL CCSD Springer Verlag
Résumé : International audience
Bone Morphogenetic Protein 9 (BMP9) has been recently found to be the physiological ligand for the activin receptor-like kinase 1 (ALK1), and to be a major circulating vascular quiescence factor. Moreover, a soluble chimeric ALK1 protein (ALK1-Fc) has recently been developed and showed powerful anti-tumor growth and anti-angiogenic effects. However, not much is known concerning BMP9. This prompted us to investigate the human endogenous sources of this cytokine and to further characterize its circulating form(s) and its function. Analysis of BMP9 expression reveals that BMP9 is produced by hepatocytes and intrahepatic biliary epithelial cells. Gel filtration analysis combined with ELISA and biological assays demonstrate that BMP9 circulates in plasma (1) as an unprocessed inactive form that can be further activated by furin a serine endoprotease, and (2) as a mature and fully active form (composed of the mature form associated with its prodomain). Analysis of BMP9 circulating levels during mouse development demonstrates that BMP9 peaks during the first 3 weeks after birth and then decreases to 2 ng/mL in adulthood. We also show that circulating BMP9 physiologically induces a constitutive Smad1/5/8 phosphorylation in endothelial cells. Taken together, our results argue for the role of BMP9 as a hepatocyte-derived factor, circulating in inactive (40%) and active (60%) forms, the latter constantly activating endothelial cells to maintain them in a resting state.
ISSN: 1420-682X

hal-00681969
https://hal.archives-ouvertes.fr/hal-00681969
DOI : 10.1007/s00018-011-0751-1
PUBMED : 21710321

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 American Society for Biochemistry and Molecular Biology
Résumé : International audience
Polycyclic aromatic hydrocarbons (PAHs) such as benzo(a)pyrene (B(a)P) are widely distributed environmental contaminants, known as potent ligands of the aryl hydrocarbon receptor (AhR). These chemicals trigger an early and transient increase of intracellular calcium concentration ([Ca(2+)](i)), required for AhR-related effects of PAHs. The mechanisms involved in this calcium mobilization were investigated in the present study. We demonstrated that B(a)P-mediated [Ca(2+)](i) induction was prevented in endothelial HMEC-1 cells by counteracting β2-adrenoreceptor (β2ADR) activity using pharmacological antagonists, anti-β2ADR antibodies, or siRNA-mediated knockdown of β2ADR expression; by contrast, it was strongly potentiated by β2ADR overexpression in human kidney HEK293 cells. B(a)P was shown, moreover, to directly bind to β2ADR, as assessed by in vitro binding assays and molecular modeling. Pharmacological inhibition and/or siRNA-mediated silencing of various signaling actors acting downstream of β2ADR in a sequential manner, such as G protein, adenylyl cyclase, Epac-1 protein, and inositol 1,4,5-trisphosphate (IP(3))/IP(3) receptor, were next demonstrated to prevent B(a)P-induced calcium signal. Inhibition or knockdown of these signaling elements, as well as the use of chemical β-blockers, were finally shown to counteract B(a)P-mediated induction of cytochrome P-450 1B1, a prototypical AhR target gene. Taken together, our results show that B(a)P binds directly to β2ADR and consequently utilizes β2ADR machinery to mobilize [Ca(2+)](i), through activation of a G protein/adenylyl cyclase/cAMP/Epac-1/IP(3) pathway. This β2ADR-dependent signaling pathway activated by PAHs may likely be crucial for PAH-mediated up-regulation of AhR target genes, thus suggesting a contribution of β2ADR to the health-threatening effects of these environmental pollutants.
ISSN: 0021-9258

hal-00682497
https://hal.archives-ouvertes.fr/hal-00682497
DOI : 10.1074/jbc.M111.319970
PUBMED : 22167199

Éditeur(s) : HAL CCSD American Society for Microbiology
Résumé : International audience
The bivalve Codakia orbicularis, hosting sulfur-oxidizing gill endosymbionts, was starved (in artificial seawater filtered through a 0.22- m-pore-size membrane) for a long-term experiment (4 months). The effects of starvation were observed using transmission electron microscopy, fluorescence in situ hybridization and catalyzed reporter deposition (CARD-FISH), and flow cytometry to monitor the anatomical and physiological modifications in the gill organization of the host and in the symbiotic population housed in bacteriocytes. The abundance of the symbiotic population decreased through starvation, with a loss of one-third of the bacterial population each month, as shown by CARD-FISH. At the same time, flow cytometry revealed significant changes in the physiology of symbiotic cells, with a decrease in cell size and modifications to the nucleic acid content, while most of the symbionts maintained a high respiratory activity (measured using the 5-cyano-2,3-ditolyl tetrazolium chloride method). Progressively, the number of symbiont subpopulations was reduced, and the subsequent multigenomic state, characteristic of this symbiont in freshly collected clams, turned into one and five equivalent genome copies for the two remaining subpopulations after 3 months. Concomitant structural modifications appeared in the gill organization. Lysosymes became visible in the bacteriocytes, while large symbionts disappeared, and bacteriocytes were gradually replaced by granule cells throughout the entire lateral zone. Those data suggested that host survival under these starvation conditions was linked to symbiont digestion as the main nutritional source.
ISSN: 0099-2240

hal-00750419
https://hal.univ-antilles.fr/hal-00750419
DOI : 10.1128/AEM.02659-08