Éditeur(s) : HAL CCSD Public Library of Science
Résumé : International audience
The increased expression of the Disintegrin and Metalloprotease ADAM12 has been associated with human cancers, however its role remain unclear. We have previously reported that ADAM12 expression is induced by the transforming growth factor, TGF-β and promotes TGF-β-dependent signaling through interaction with the type II receptor of TGF-β. Here we explore the implication of ADAM12 in TGF-β-mediated epithelial to mesenchymal transition (EMT), a key process in cancer progression. We show that ADAM12 expression is correlated with EMT markers in human breast cancer cell lines and biopsies. Using a non-malignant breast epithelial cell line (MCF10A), we demonstrate that TGF-β-induced EMT increases expression of the membrane-anchored ADAM12L long form. Importantly, ADAM12L overexpression in MCF10A is sufficient to induce loss of cell-cell contact, reorganization of actin cytoskeleton, up-regulation of EMT markers and chemoresistance. These effects are independent of the proteolytic activity but require the cytoplasmic tail and are specific of ADAM12L since overexpression of ADAM12S failed to induce similar changes. We further demonstrate that ADAM12L-dependent EMT is associated with increased phosphorylation of Smad3, Akt and ERK proteins. Conversely, inhibition of TGF-β receptors or ERK activities reverses ADAM12L-induced mesenchymal phenotype. Together our data demonstrate that ADAM12L is associated with EMT and contributes to TGF-β-dependent EMT by favoring both Smad-dependent and Smad-independent pathways
ISSN: 1932-6203

hal-01207281
https://hal-univ-rennes1.archives-ouvertes.fr/hal-01207281
DOI : 10.1371/journal.pone.0139179
PUBMED : 26407179

Éditeur(s) : HAL CCSD Public Library of Science
Résumé : International audience
BACKGROUND: Gastric cancer is one of the most common cancers in the world. The "economically developed countries" life style, including diet, constitutes a risk factor favoring this cancer. Diet modulation may lower digestive cancer incidence. Among promising food components, dairy propionibacteria were shown to trigger apoptosis of human colon cancer cells, via the release of short-chain fatty acids acetate and propionate. METHODOLOGY/PRINCIPAL FINDINGS: A fermented milk, exclusively fermented by P. freudenreichii, was recently designed. In this work, the pro-apoptotic potential of this new fermented milk was demonstrated on HGT-1 human gastric cancer cells. Fermented milk supernatant induced typical features of apoptosis including chromatin condensation, formation of apoptotic bodies, DNA laddering, cell cycle arrest and emergence of a subG1 population, phosphatidylserine exposure at the plasma membrane outer leaflet, reactive oxygen species accumulation, mitochondrial transmembrane potential disruption, caspase activation and cytochrome c release. Remarkably, this new fermented milk containing P. freudenreichii enhanced the cytotoxicity of camptothecin, a drug used in gastric cancer chemotherapy. CONCLUSIONS/SIGNIFICANCE: Such new probiotic fermented milk may thus be useful as part of a preventive diet designed to prevent gastric cancer and/or as a food supplement to potentiate cancer therapeutic treatments.
ISSN: 1932-6203

inserm-00871491
http://www.hal.inserm.fr/inserm-00871491
http://www.hal.inserm.fr/inserm-00871491/document
http://www.hal.inserm.fr/inserm-00871491/file/Milk_Fermented_by_Propionibacterium_freudenreichii.accepted.pdf
DOI : 10.1371/journal.pone.0031892

Éditeur(s) : Public Library Science
Résumé : Transposable elements are major constituents of eukaryote genomes and have a great impact on genome structure and stability. They can contribute to the genetic diversity and evolution of organisms. Knowledge of their distribution among several genomes is an essential condition to study their dynamics and to better understand their role in species evolution. LTR-retrotransposons have been reported in many diverse eukaryote species, describing a ubiquitous distribution. Given their abundance, diversity and their extended ranges in C-values, environment and life styles, crustaceans are a great taxon to investigate the genomic component of adaptation and its possible relationships with TEs. However, crustaceans have been greatly underrepresented in transposable element studies. Using both degenerate PCR and in silico approaches, we have identified 35 Copia and 46 Gypsy families in 15 and 18 crustacean species, respectively. In particular, we characterized several full-length elements from the shrimp Rimicaris exoculata that is listed as a model organism from hydrothermal vents. Phylogenic analyses show that Copia and Gypsy retrotransposons likely present two opposite dynamics within crustaceans. The Gypsy elements appear relatively frequent and diverse whereas Copia are much more homogeneous, as 29 of them belong to the single GalEa clade, and species-or lineage-dependent. Our results also support the hypothesis of the Copia retrotransposon scarcity in metazoans compared to Gypsy elements. In such a context, the GalEa-like elements present an outstanding wide distribution among eukaryotes, from fishes to red algae, and can be even highly predominant within a large taxon, such as Malacostraca. Their distribution among crustaceans suggests a dynamics that follows a "domino days spreading'' branching process in which successive amplifications may interact positively.
Plos One (1932-6203) (Public Library Science), 2013-03 , Vol. 8 , N. 3 , P. e57675

Droits : This is an open-access article, free of all copyright, and may be freely reproduced, distributed, transmitted, modified, built upon, or otherwise used by anyone for any lawful purpose. The work is made available under the Creative Commons CC0 public domain dedication.
http://archimer.ifremer.fr/doc/00185/29656/28030.pdf
DOI:10.1371/journal.pone.0057675
http://archimer.ifremer.fr/doc/00185/29656/

Éditeur(s) : HAL CCSD Public Library of Science
Résumé : International audience
BACKGROUND: Estrogens are thought to play a critical role in prostate carcinogenesis. It has been suggested that polymorphisms of genes encoding enzymes involved in estrogen metabolism are risk factors for prostate cancer. However, few studies have been performed on populations of African ancestry, which are known to have a high risk of prostate cancer. OBJECTIVE: We investigated whether functional polymorphisms of CYP17, CYP19, CYP1B1, COMT and UGT1A1 affected the risk of prostate cancer in two different populations of African ancestry. METHODS: In Guadeloupe (French West Indies), we compared 498 prostate cancer patients and 565 control subjects. In Kinshasa (Democratic Republic of Congo), 162 prostate cancer patients were compared with 144 controls. Gene polymorphisms were determined by the SNaPshot technique or short tandem repeat PCR analysis. Logistic regression was used to estimate adjusted odds ratios (OR) and 95% confidence intervals (CI). RESULTS: The AA genotype and the A allele of rs4680 (COMT) appeared to be inversely associated with the risk of prostate cancer in adjusted models for both Afro-Caribbean and native African men. For the A allele, a significant inverse association was observed among cases with low-grade Gleason scores and localized clinical stage, in both populations. CONCLUSIONS: These preliminary results support the hypothesis that polymorphisms of genes encoding enzymes involved in estrogen metabolism may modulate the risk of prostate cancer in populations of African ancestry
ISSN: 1932-6203

hal-01305477
https://hal-univ-rennes1.archives-ouvertes.fr/hal-01305477
DOI : 10.1371/journal.pone.0153609
PUBMED : 27074016

Éditeur(s) : HAL CCSD Public Library of Science
Résumé : International audience
Two of the crucial aspects of human immunodeficiency virus (HIV) infection are (i) viral persistence in reservoirs (precluding viral eradication) and (ii) chronic inflammation (directly associated with all-cause morbidities in antiretroviral therapy (ART)-controlled HIV-infected patients). The objective of the present study was to assess the potential involvement of adipose tissue in these two aspects. Adipose tissue is composed of adipocytes and the stromal vascular fraction (SVF); the latter comprises immune cells such as CD4+ T cells and macrophages (both of which are important target cells for HIV). The inflammatory potential of adipose tissue has been extensively described in the context of obesity. During HIV infection, the inflammatory profile of adipose tissue has been revealed by the occurrence of lipodystrophies (primarily related to ART). Data on the impact of HIV on the SVF (especially in individuals not receiving ART) are scarce. We first analyzed the impact of simian immunodeficiency virus (SIV) infection on abdominal subcutaneous and visceral adipose tissues in SIVmac251 infected macaques and found that both adipocytes and adipose tissue immune cells were affected. The adipocyte density was elevated, and adipose tissue immune cells presented enhanced immune activation and/or inflammatory profiles. We detected cell-associated SIV DNA and RNA in the SVF and in sorted CD4+ T cells and macrophages from adipose tissue. We demonstrated that SVF cells (including CD4+ T cells) are infected in ART-controlled HIV-infected patients. Importantly, the production of HIV RNA was detected by in situ hybridization, and after the in vitro reactivation of sorted CD4+ T cells from adipose tissue. We thus identified adipose tissue as a crucial cofactor in both viral persistence and chronic immune activation/inflammation during HIV infection. These observations open up new therapeutic strategies for limiting the size of the viral reservoir and decreasing low-grade chronic inflammation via the modulation of adipose tissue-related pathways
ISSN: 1553-7366

Droits : http://creativecommons.org/licenses/by/
hal-01207287
https://hal-univ-rennes1.archives-ouvertes.fr/hal-01207287
https://hal-univ-rennes1.archives-ouvertes.fr/hal-01207287/document
https://hal-univ-rennes1.archives-ouvertes.fr/hal-01207287/file/journal.ppat.1005153.pdf
DOI : 10.1371/journal.ppat.1005153

Éditeur(s) : HAL CCSD Public Library of Science
Résumé : International audience
Understanding how communities respond to natural disturbances is fundamental to assess the mechanisms of ecosystem resistance and resilience. However, ecosystem responses to natural disturbances are rarely monitored both through space and time, while the factors promoting ecosystem stability act at various temporal and spatial scales. Hence, assessing both the spatial and temporal variations in species composition is important to comprehensively explore the effects of natural disturbances. Here, we suggest a framework to better scrutinize the mechanisms underlying community responses to disturbances through both time and space. Our analytical approach is based on beta diversity decomposition into two components, replacement and biomass difference. We illustrate this approach using a 9-year monitoring of coral reef fish communities off Moorea Island (French Polynesia), which encompassed two severe natural disturbances: a crown-of-thorns starfish outbreak and a hurricane. These disturbances triggered a fast logistic decline in coral cover, which suffered a 90% decrease on all reefs. However, we found that the coral reef fish composition remained largely stable through time and space whereas compensatory changes in bio-mass among species were responsible for most of the temporal fluctuations, as outlined by the overall high contribution of the replacement component to total beta diversity. This suggests that, despite the severity of the two disturbances, fish communities exhibited high resistance and the ability to reorganize their compositions to maintain the same level of total community biomass as before the disturbances. We further investigated the spatial congruence of this pattern and showed that temporal dynamics involved different species across sites; yet, herbivores controlling the proliferation of algae that compete with coral communities were consistently favored. These results suggest that compensatory changes in bio-mass among species and spatial heterogeneity in species responses can provide further
ISSN: 1932-6203

hal-01212344
https://hal-univ-perp.archives-ouvertes.fr/hal-01212344
https://hal-univ-perp.archives-ouvertes.fr/hal-01212344/document
https://hal-univ-perp.archives-ouvertes.fr/hal-01212344/file/journal.pone.0138696.pdf
DOI : 10.1371/journal.pone.0138696

Éditeur(s) : HAL CCSD Public Library of Science
Résumé : International audience
We conducted a survey along three belt transects located at increasing distances from the coast to determine whether a non-random arboreal ant assemblage, such as an ant mosaic, exists in the rainforest on the Masoala Peninsula, Madagascar. In most tropical rainforests, very populous colonies of territorially dominant arboreal ant species defend absolute territories distributed in a mosaic pattern. Among the 29 ant species recorded, only nine had colonies large enough to be considered potentially territorially dominant; the remaining species had smaller colonies and were considered non-dominant. Nevertheless, the null-model analyses used to examine the spatial structure of their assemblages did not reveal the existence of an ant mosaic. Inland, up to 44% of the trees were devoid of dominant arboreal ants, something not reported in other studies. While two Crematogaster species were not associated with one another, Brachymyrmex cordemoyi was positively associated with Technomyrmex albipes, which is considered an invasive species-a non-indigenous species that has an adverse ecological effect on the habitats it invades. The latter two species and Crematogaster ranavalonae were mutually exclusive. On the other hand, all of the trees in the coastal transect and at least 4 km of coast were occupied by T. albipes, and were interconnected by columns of workers. Technomyrmex albipes workers collected from different trees did not attack each other during confrontation tests, indicating that this species has formed a supercolony along the coast. Yet interspecific aggressiveness did occur between T. albipes and Crematogaster ranavalonae, a native species which is likely territorially dominant based on our intraspecific confrontation tests. These results suggest that the Masoala rainforest is threatened by a potential invasion by T. albipes, and that the penetration of this species further inland might be facilitated by the low density of native, territorially dominant arboreal ants normally able to limit its progression.
ISSN: 1932-6203

hal-00817444
https://hal.archives-ouvertes.fr/hal-00817444
https://hal.archives-ouvertes.fr/hal-00817444/document
https://hal.archives-ouvertes.fr/hal-00817444/file/Dejean2010_Spatial.pdf
DOI : 10.1371/journal.pone.0009319

Éditeur(s) : HAL CCSD Public Library of Science
Résumé : International audience
The development of inflammatory granulomas around infected Kupffer cells is necessary for hepatic parasite clearance during visceral leishmaniasis. Invariant NKT (iNKT) cells are predominant T cells in the mouse liver and can synthesize large quantities of IL-4 and IFN-γ, two cytokines involved in granuloma formation. This study analyzed the role of iNKT cells in the hepatic immune response during Leishmania donovani infection, using a murine model of wild-type (WT) and iNKT cell-deficient (Jα18⁻/⁻) C57BL/6 mice sacrificed 15, 30 or 60 days post-infection. We recorded hepatic parasite loads, cytokine expression, and analyzed granulomatous response by immunohistochemistry and hepatic immune cell infiltration by flow cytometry. Whereas WT animals rapidly controlled the infection and developed an inflammatory response associated with a massive influx of iNKT cells observed by flow cytometry, Jα18⁻/⁻ mice had significantly higher parasitic loads on all time points. This lack of control of parasite burden was associated with a delay in granuloma maturation (28.1% of large granulomas at day 60 versus 50.7% in WT). Cytokine transcriptome analysis showed that mRNA of 90/101 genes encoding chemokines, cytokines and their receptors, was underexpressed in Jα18⁻/⁻ mice. Detection of IL-4 and TNF-α by ELISA in liver extracts was also significantly lower in Jα18⁻/⁻ mice. Consistent with flow cytometry analysis, cytokinome profile in WT mice showed a bias of expression towards T cell-chemoattractant chemokines on D15, and displayed a switch towards expression of granulocytes and/or monocytes -chemoattractant chemokines on D60. In Jα18⁻/⁻ mice, the significantly lower expression of CXCL5, MIP-2 and CCL2 mRNA was correlated with a defect in myeloperoxidase positive-cell attraction observed by immunohistochemistry and with a lower granulocyte and monocyte infiltration in the liver, as shown by flow cytometry. These data indicate that iNKT cells play a role in early and sustained pro-inflammatory cytokine response warranting efficient organization of hepatic granulomas and parasite clearance.
ISSN: 1932-6203

hal-00696897
https://hal.archives-ouvertes.fr/hal-00696897
https://hal.archives-ouvertes.fr/hal-00696897/document
https://hal.archives-ouvertes.fr/hal-00696897/file/Invariant_NKT_Cells_Drive-accepted.pdf
DOI : 10.1371/journal.pone.0033413

Éditeur(s) : HAL CCSD Public Library of Science
Résumé : International audience
Leg ulcer is a disabling complication in patients with sickle cell anemia (SCA) but the exact pathophysiological mechanisms are unknown. The aim of this study was to identify the hematological and hemorheological alterations associated with recurrent leg ulcers. Sixty-two SCA patients who never experienced leg ulcers (ULC-) and 13 SCA patients with a positive history of recurrent leg ulcers (ULC+) - but with no leg ulcers at the time of the study - were recruited. All patients were in steady state condition. Blood was sampled to perform hematological, biochemical (hemolytic markers) and hemorheological analyses (blood viscosity, red blood cell deformability and aggregation properties). The hematocrit-to-viscosity ratio (HVR), which reflects the red blood cell oxygen transport efficiency, was calculated for each subject. Patients from the ULC+ group were older than patients from the ULC- group. Anemia (red blood cell count, hematocrit and hemoglobin levels) was more pronounced in the ULC+ group. Lactate dehydrogenase level was higher in the ULC+ group than in the ULC- group. Neither blood viscosity, nor RBC aggregation properties differed between the two groups. HVR was lower and RBC deformability tended to be reduced in the ULC+ group. Our study confirmed increased hemolytic rate and anemia in SCA patients with leg ulcers recurrence. Furthermore, our data suggest that although systemic blood viscosity is not a major factor involved in the pathophysiology of this complication, decreased red blood cell oxygen transport efficiency (i.e., low hematocrit/viscosity ratio) may play a role.
ISSN: 1932-6203

inserm-00922105
http://www.hal.inserm.fr/inserm-00922105
http://www.hal.inserm.fr/inserm-00922105/document
http://www.hal.inserm.fr/inserm-00922105/file/2013_Connes_-_Decreased_Hematocrit.pdf
DOI : 10.1371/journal.pone.0079680

Éditeur(s) : Public Library Science
Résumé : The blue mussel, Mytilus edulis, is a commercially important species, with production based on both fisheries and aquaculture. Dynamic Energy Budget (DEB) models have been extensively applied to study its energetics but such applications require a deep understanding of its nutrition, from filtration to assimilation. Being filter feeders, mussels show multiple responses to temporal fluctuations in their food and environment, raising questions that can be investigated by modeling. To provide a better insight into mussel–environment interactions, an experiment was conducted in one of the main French growing zones (Utah Beach, Normandy). Mussel growth was monitored monthly for 18 months, with a large number of environmental descriptors measured in parallel. Food proxies such as chlorophyll a, particulate organic carbon and phytoplankton were also sampled, in addition to non-nutritious particles. High-frequency physical data recording (e.g., water temperature, immersion duration) completed the habitat description. Measures revealed an increase in dry flesh mass during the first year, followed by a high mass loss, which could not be completely explained by the DEB model using raw external signals. We propose two methods that reconstruct food from shell length and dry flesh mass variations. The former depends on the inversion of the growth equation while the latter is based on iterative simulations. Assemblages of food proxies are then related to reconstructed food input, with a special focus on plankton species. A characteristic contribution is attributed to these sources to estimate nutritional values for mussels. M. edulis shows no preference between most plankton life history traits. Selection is based on the size of the ingested particles, which is modified by the volume and social behavior of plankton species. This finding reveals the importance of diet diversity and both passive and active selections, and confirms the need to adjust DEB models to different populations and sites.
Plos One (1932-6203) (Public Library Science), 2014-10 , Vol. 9 , N. 10 , P. 1-13

Droits : 2014 Picoche et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited
http://archimer.ifremer.fr/doc/00218/32895/31380.pdf
http://archimer.ifremer.fr/doc/00218/32895/31381.pdf
http://archimer.ifremer.fr/doc/00218/32895/31382.pdf
http://archimer.ifremer.fr/doc/00218/32895/31383.pdf
http://archimer.ifremer.fr/doc/00218/32895/31384.pdf

Éditeur(s) : HAL CCSD Public Library of Science
Résumé : Simple sequence repeat (SSR) markers are widely used tools for inferences about genetic diversity, phylogeography and spatial genetic structure. Their applications assume that variation among alleles is essentially caused by an expansion or contraction of the number of repeats and that, accessorily, mutations in the target sequences follow the stepwise mutation model (SMM). Generally speaking, PCR amplicon sizes are used as direct indicators of the number of SSR repeats composing an allele with the data analysis either ignoring the extent of allele size differences or assuming that there is a direct correlation between differences in amplicon size and evolutionary distance. However, without precisely knowing the kind and distribution of polymorphism within an allele (SSR and the associated flanking region (FR) sequences), it is hard to say what kind of evolutionary message is conveyed by such a synthetic descriptor of polymorphism as DNA amplicon size. In this study, we sequenced several SSR alleles in multiple populations of three divergent tree genera and disentangled the types of polymorphisms contained in each portion of the DNA amplicon containing an SSR. The patterns of diversity provided by amplicon size variation, SSR variation itself, insertions/deletions (indels), and single nucleotide polymorphisms (SNPs) observed in the FRs were compared. Amplicon size variation largely reflected SSR repeat number. The amount of variation was as large in FRs as in the SSR itself. The former contributed significantly to the phylogenetic information and sometimes was the main source of differentiation among individuals and populations contained by FR and SSR regions of SSR markers. The presence of mutations occurring at different rates within a marker's sequence offers the opportunity to analyse evolutionary events occurring on various timescales, but at the same time calls for caution in the interpretation of SSR marker data when the distribution of within-locus polymorphism is not known.
ISSN: 1932-6203

hal-01190764
https://hal.archives-ouvertes.fr/hal-01190764
PRODINRA : 214530
PUBMED : 22808236
DOI : 10.1371/journal.pone.0040699

Éditeur(s) : HAL CCSD Public Library of Science
Résumé : International audience
Growth hormone (GH) may stimulate water loss during exercise by activating sweating. This study investigated GH secretion and water loss during sequential cycling and running, taking postural changes into account. The two exercise segments had similar durations and were performed at the same relative intensity to determine their respective contributions to water loss and the plasma volume variation noted in such trials. Eight elite triathletes first performed an incremental cycle test to assess maximal oxygen consumption. Then, the triathletes performed one of two trials in randomized order: constant submaximal cycling followed by treadmill running (C 1 –R 2) or an inversed succession of running followed by cycling (R 1 –C 2). Each segment of both trials was performed for 20 minutes at ,75% of maximal oxygen consumption. The second trial, reversing the segment order of the first trial, took place two weeks later. During cycling, the triathletes used their own bicycles equipped with a profiled handlebar. Blood sampling (for GH concentrations, plasma viscosity and plasma volume variation) was conducted at rest and after each segment while water loss was estimated from the post-and pre-measures. GH increases were significantly lower in R 2 than C 2 (72.2650.1 vs. 164.06157 ng.ml 21 .min 21 , respectively; P,0.05). Water loss was significantly lower after C 1 –R 2 than R 1 –C 2 (11056163 and 12356153 ml, respectively; P,0.05). Plasma volume variation was significantly negative in C 1 and R 1 (26.1562.0 and 23.1665.0%, respectively; P,0.05), not significant in C 2 , and significantly positive for seven subjects in R 2 (4.0563.1%). We concluded that the lower GH increases in R 2 may have contributed to the smaller reduction in plasma volume by reducing sweating. Moreover, this lower GH response could be explained by the postural change during the transition from cycling to running. We recommend to pay particular attention to their hydration status during R 1 which could limit a potential dehydration during C 2 .
ISSN: 1932-6203

hal-01136734
https://hal.univ-antilles.fr/hal-01136734
https://hal.univ-antilles.fr/hal-01136734/document
https://hal.univ-antilles.fr/hal-01136734/file/Galy%20et%20al.%20-%202014%20-%20Sequential%20exercise%20in%20triathletes%20Variations%20in%20GH%20and%20water%20loss.pdf
DOI : 10.1371/journal.pone.0096145

Éditeur(s) : HAL CCSD Public Library of Science
Résumé : International audience
The six-minute walk test is a well-established submaximal exercise reflecting the functional status and the clinical severity of sickle cell patients. The aim of the present cross-sectional study was to investigate the biological determinants of the six-minute walk test performance in children with sickle cell anemia. Hematological and hemorheological parameters, pulmonary function and the six-minute walk test performance were determined in 42 children with sickle cell anemia at steady state. The performance during the six-minute walk test was normalized for age, sex and height and expressed as percentage of the predicted six-minute walk distance. We showed that a high level of anemia, a low fetal hemoglobin expression and low red blood cell deformability were independent predictors of a low six-minute walk test performance. This study describes for the first time the impact of blood rheology in the six-minute walk test performance in children with sickle cell anemia.
ISSN: 1932-6203

inserm-00922110
http://www.hal.inserm.fr/inserm-00922110
http://www.hal.inserm.fr/inserm-00922110/document
http://www.hal.inserm.fr/inserm-00922110/file/2013_Waltz_-_Hematological_and_hemorheological_determinants_6_minutes.pdf
DOI : 10.1371/journal.pone.0077830

Éditeur(s) : HAL CCSD Public Library of Science
Résumé : International audience
Sea cows (manatees, dugongs) are the only living marine mammals to feed solely on aquatic plants. Unlike whales or dolphins (Cetacea), the earliest evolutionary history of sirenians is poorly documented, and limited to a few fossils including skulls and skeletons of two genera composing the stem family of Prorastomidae (Prorastomus and Pezosiren). Surprisingly, these fossils come from the Eocene of Jamaica, while stem Hyracoidea and Proboscidea - the putative sister-groups to Sirenia - are recorded in Africa as early as the Late Paleocene. So far, the historical biogeography of early Sirenia has remained obscure given this paradox between phylogeny and fossil record. Here we use X-ray microtomography to investigate a newly discovered sirenian petrosal from the Eocene of Tunisia. This fossil represents the oldest occurrence of sirenians in Africa. The morphology of this petrosal is more primitive than the Jamaican prorastomids' one, which emphasizes the basal position of this new African taxon within the Sirenia clade. This discovery testifies to the great antiquity of Sirenia in Africa, and therefore supports their African origin. While isotopic analyses previously suggested sirenians had adapted directly to the marine environment, new paleoenvironmental evidence suggests that basal-most sea cows were likely restricted to fresh waters.
ISSN: 1932-6203

hal-00807308
https://hal.archives-ouvertes.fr/hal-00807308
DOI : 10.1371/journal.pone.0054307

Éditeur(s) : Public Library Science
Résumé : Where conservation resources are limited and conservation targets are diverse, robust yet flexible priority-setting frameworks are vital. Priority-setting is especially important for geographically widespread species with distinct populations subject to multiple threats that operate on different spatial and temporal scales. Marine turtles are widely distributed and exhibit intra-specific variations in population sizes and trends, as well as reproduction and morphology. However, current global extinction risk assessment frameworks do not assess conservation status of spatially and biologically distinct marine turtle Regional Management Units (RMUs), and thus do not capture variations in population trends, impacts of threats, or necessary conservation actions across individual populations. To address this issue, we developed a new assessment framework that allowed us to evaluate, compare and organize marine turtle RMUs according to status and threats criteria. Because conservation priorities can vary widely (i.e. from avoiding imminent extinction to maintaining long-term monitoring efforts) we developed a "conservation priorities portfolio" system using categories of paired risk and threats scores for all RMUs (n = 58). We performed these assessments and rankings globally, by species, by ocean basin, and by recognized geopolitical bodies to identify patterns in risk, threats, and data gaps at different scales. This process resulted in characterization of risk and threats to all marine turtle RMUs, including identification of the world's 11 most endangered marine turtle RMUs based on highest risk and threats scores. This system also highlighted important gaps in available information that is crucial for accurate conservation assessments. Overall, this priority-setting framework can provide guidance for research and conservation priorities at multiple relevant scales, and should serve as a model for conservation status assessments and priority-setting for widespread, long-lived taxa.
Plos One (1932-6203) (Public Library Science), 2011-09 , Vol. 6 , N. 9 , P. 1-14

Droits : 2011 Wallace et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License
http://archimer.ifremer.fr/doc/00050/16097/13573.pdf
DOI:10.1371/journal.pone.0024510
http://archimer.ifremer.fr/doc/00050/16097/

Éditeur(s) : HAL CCSD Public Library of Science
Résumé : International audience
The susceptibility of Anopheles mosquitoes to Plasmodium infections relies on complex interactions between the insect vector and the malaria parasite. A number of studies have shown that the mosquito innate immune responses play an important role in controlling the malaria infection and that the strength of parasite clearance is under genetic control, but little is known about the influence of environmental factors on the transmission success. We present here evidence that the composition of the vector gut microbiota is one of the major components that determine the outcome of mosquito infections. A. gambiae mosquitoes collected in natural breeding sites from Cameroon were experimentally challenged with a wild P. falciparum isolate, and their gut bacterial content was submitted for pyrosequencing analysis. The meta-taxogenomic approach revealed a broader richness of the midgut bacterial flora than previously described. Unexpectedly, the majority of bacterial species were found in only a small proportion of mosquitoes, and only 20 genera were shared by 80% of individuals. We show that observed differences in gut bacterial flora of adult mosquitoes is a result of breeding in distinct sites, suggesting that the native aquatic source where larvae were grown determines the composition of the midgut microbiota. Importantly, the abundance of Enterobacteriaceae in the mosquito midgut correlates significantly with the Plasmodium infection status. This striking relationship highlights the role of natural gut environment in parasite transmission. Deciphering microbe-pathogen interactions offers new perspectives to control disease transmission.
ISSN: 1553-7366

hal-01546176
https://hal.archives-ouvertes.fr/hal-01546176
DOI : 10.1371/journal.ppat.1002742

Éditeur(s) : HAL CCSD Public Library of Science
Résumé : International audience
Purpose: This study compares the effects of neutral temperature, cold and ice-slush beverages, with and without 0.5% menthol on cycling performance, core temperature (T co) and stress responses in a tropical climate (hot and humid conditions). Methods: Twelve trained male cyclists/triathletes completed six 20-km exercise trials against the clock in 30.7uC60.8uC and 78%60.03% relative humidity. Before and after warm-up, and before exercise and every 5 km during exercise, athletes drank 190 mL of either aromatized (i.e., with 0.5 mL of menthol (5 gr/L)) or a non-aromatized beverage (neutral temperature: 23uC60.1uC, cold: 3uC60.1uC, or ice-slush: 21uC60.7uC). During the trials, heart rate (HR) was continuously monitored, whereas core temperature (T co), thermal comfort (TC), thermal sensation (TS) and rate of perceived exertion (RPE) were measured before and after warm-up, every 5 km of exercise, and at the end of exercise and after recovery. Results: Both the beverage aroma (P,0.02) and beverage temperature (P,0.02) had significant and positive effects on performance, which was considerably better with ice-slush than with a neutral temperature beverage, whatever the aroma (P,0.002), and with menthol vs non-menthol (P,0.02). The best performances were obtained with ice-slush/menthol and cold/menthol, as opposed to neutral/menthol. No differences were noted in HR and T co between trials. Conclusion: Cold water or ice-slush with menthol aroma seems to be the most effective beverage for endurance exercise in a tropical climate. Further studies are needed to explore its effects in field competition.
ISSN: 1932-6203

hal-01135125
https://hal.univ-antilles.fr/hal-01135125
https://hal.univ-antilles.fr/hal-01135125/document
https://hal.univ-antilles.fr/hal-01135125/file/Riera%20et%20al.%20-%202014%20-%20Physical%20and%20perceptual%20cooling%20with%20beverages%20to%20increase%20cycle%20performance%20in%20a%20tropical%20climate%284%29.pdf
DOI : 10.1371/journal.pone.0103718

Éditeur(s) : Public Library Science
Résumé : Global change and its associated temperature increase has directly or indirectly changed the distributions of hosts and pathogens, and has affected host immunity, pathogen virulence and growth rates. This has resulted in increased disease in natural plant and animal populations worldwide, including scleractinian corals. While the effects of temperature increase on immunity and pathogen virulence have been clearly identified, their interaction, synergy and relative weight during pathogenesis remain poorly documented. We investigated these phenomena in the interaction between the coral Pocillopora damicornis and the bacterium Vibrio coralliilyticus, for which the infection process is temperature-dependent. We developed an experimental model that enabled unraveling the effects of thermal stress, and virulence vs. non-virulence of the bacterium. The physiological impacts of various treatments were quantified at the transcriptome level using a combination of RNA sequencing and targeted approaches. The results showed that thermal stress triggered a general weakening of the coral, making it more prone to infection, non-virulent bacterium induced an 'efficient' immune response, whereas virulent bacterium caused immuno-suppression in its host.
Plos One (1932-6203) (Public Library Science), 2014-09 , Vol. 9 , N. 9 , P. 1-15

Droits : This is an open-access article, free of all copyright, and may be freely reproduced, distributed, transmitted, modified, built upon, or otherwise used by anyone for any lawful purpose. The work is made available under the Creative Commons CC0 public domain dedication.
http://archimer.ifremer.fr/doc/00221/33265/31738.pdf
DOI:10.1371/journal.pone.0107672
http://archimer.ifremer.fr/doc/00221/33265/

Éditeur(s) : HAL CCSD Public Library of Science
Résumé : International audience
Chelonanthus alatus is a bat-pollinated, pioneer Gentianaceae that clusters in patches where still-standing, dried-out stems are interspersed among live individuals. Flowers bear circum-floral nectaries (CFNs) that are attractive to ants, and seed dispersal is both barochorous and anemochorous. Although, in this study, live individuals never sheltered ant colonies, dried-out hollow stems--that can remain standing for 2 years--did. Workers from species nesting in dried-out stems as well as from ground-nesting species exploited the CFNs of live C. alatus individuals in the same patches during the daytime, but were absent at night (when bat pollination occurs) on 60.5% of the plants. By visiting the CFNs, the ants indirectly protect the flowers--but not the plant foliage--from herbivorous insects. We show that this protection is provided mostly by species nesting in dried-out stems, predominantly Pseudomyrmex gracilis. That dried-out stems remain standing for years and are regularly replaced results in an opportunistic, but stable association where colonies are sheltered by one generation of dead C. alatus while the live individuals nearby, belonging to the next generation, provide them with nectar; in turn, the ants protect their flowers from herbivores. We suggest that the investment in wood by C. alatus individuals permitting still-standing, dried-out stems to shelter ant colonies constitutes an extended phenotype because foraging workers protect the flowers of live individuals in the same patch. Also, through this process these dried-out stems indirectly favor the reproduction (and so the fitness) of the next generation including both their own offspring and that of their siblings, all adding up to a potential case of inclusive fitness in plants.
ISSN: 1932-6203

hal-00825845
https://hal.archives-ouvertes.fr/hal-00825845
https://hal.archives-ouvertes.fr/hal-00825845/document
https://hal.archives-ouvertes.fr/hal-00825845/file/Dejean2011_Inherited.pdf
DOI : 10.1371/journal.pone.0018071

Éditeur(s) : HAL CCSD Public Library of Science
Résumé : International audience
ISSN: 1935-2727

inserm-00919502
http://www.hal.inserm.fr/inserm-00919502
http://www.hal.inserm.fr/inserm-00919502/document
http://www.hal.inserm.fr/inserm-00919502/file/2013_Nacher_-_Disseminated_histo_in_hiv_in_south_america_a_neglected_killer_continues_on_its_rampage.pdf
DOI : 10.1371/journal.pntd.0002319