Éditeur(s) : HAL CCSD BioMed Central
Résumé : [b]Background[/b]: [i]Amblyomma variegatum[/i] and [i]A. hebraeum[/i] are two ticks of veterinary and human health importance in south-east Africa. In Zimbabwe they occupy parapatric (marginally overlapping and juxtaposed) distributions. Understanding the mechanisms behind this parapatry is essential for predicting the spatio-temporal dynamics of Amblyomma spp. and the impacts of associated diseases. It has been hypothesized that exclusive competition between these species results from competition at the levels of male signal reception (attraction-aggregation-attachment pheromones) or sexual competition for mates. This hypothesis predicts that the parapatry described in Zimbabwe could also be present in other countries in the region. [br/][b]Methods[/b]: To explore this competitive exclusion hypothesis we conducted field surveys at the two species' range limits in Mozambique to identify areas of sympatry (overlapping areas) and to study potential interactions (communicative and reproductive interference effects) in those areas. At sympatric sites, hetero-specific mating pairs were collected and inter-specific attractiveness/repellent effects acting at long and short distances were assessed by analyzing species co-occurrences on co-infested herds and co-infested hosts.[br/] [b]Results[/b]: Co-occurrences of both species at sampling sites were infrequent and localized in areas where both tick and host densities were low. At sympatric sites, high percentages of individuals of both species shared attachment sites on hosts and inter-specific mating rates were high. Although cross-mating rates were not significantly different for[i] A. variegatum[/i] and [i]A. hebraeum[/i] females, attraction towards hetero-specific males was greater for [i]A. hebraeum[/i] females than for A. variegatum females and we observed small asymmetrical repellent effects between males at attachment sites.[br/][b]Conclusions[/b]: Our observations suggest near-symmetrical reproductive interference between [i]A. variegatum[/i] and [i]A. hebraeum[/i], despite between-species differences in the strength of reproductive isolation barriers acting at the aggregation, fixation and partner contact levels. Theoretical models predict that sexual competition coupled with hybrid inviability, greatly reduces the probability of one species becoming established in an otherwise suitable location when the other species is already established. This mechanism can explain why the parapatric boundary in Mozambique has formed within an area of low tick densities and relatively infrequent host-mediated dispersal events.
ISSN: 1756-3305

hal-01220744
https://hal.archives-ouvertes.fr/hal-01220744
https://hal.archives-ouvertes.fr/hal-01220744/document
https://hal.archives-ouvertes.fr/hal-01220744/file/2015%20Bournez%20Parasites%20%26%20Vectors_%7B365AAFF5-7041-480B-9B77-9CD0485A9B72%7D.pdf
DOI : 10.1186/s13071-015-1116-7

Éditeur(s) : HAL CCSD Georg Thieme Verlag
Résumé : International audience
Oil from the nuts of Calophyllum inophyllum, locally called "Tamanu oil" in French Polynesia, was traditionally used for wound healing and to cure various skin problems and ailments. The skin-active effect of "Tamanu oil emulsion" was investigated on human skin cells (keratinocytes and dermal fibroblasts) and showed cell proliferation, glycosaminoglycan and collagen production, and wound healing activity. Transcriptomic analysis of the treated cells revealed gene expression modulation including genes involved in the metabolic process implied in O-glycan biosynthesis, cell adhesion, and cell proliferation. The presence of neoflavonoids as bioactive constituents in Tamanu oil emulsion may contribute to these biological activities. Altogether, consistent data related to targeted histological and cellular functions brought new highlights on the mechanisms involved in these biological processes induced by Tamanu oil effects in skin cells.
ISSN: 0032-0943

hal-01592246
https://hal.archives-ouvertes.fr/hal-01592246
DOI : 10.1055/s-0042-108205

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
Although many studies reported mechanisms involved in the positive regulation of estrogens (E2) target genes, very little is known concerning the repressive effect of E2. In this study, we explored the molecular mechanisms by which E2 regulates CXCR7 expression in breast cancer cells. Our results show that E2-mediated down-regulation of CXCR7 occurs at the transcriptional level as demonstrated using actinomycin D and requires estrogen receptor alpha (ERα). In addition, CXCR7 is a primary ERα-target gene because the effect of E2 does not require the synthesis of an intermediary protein as revealed by the translational inhibitor cycloheximide treatment. Using an inhibitor of the NFκB pathway and chromatin immunoprecipitation assays, we demonstrated that NFκB is necessary for the high expression of CXCR7 gene and is recruited to the proximal promoter of the CXCR7 gene. Interestingly, the chromatin immunoprecipitation analyses also showed that E2-treatment significantly prevented the recruitment of NFκB to the promoter. Altogether, our results demonstrate that E2, through ERα, directly down-regulates CXCR7 expression by interfering with NFκB transcription factor at the promoter level.
ISSN: 0006-291X

inserm-00808966
http://www.hal.inserm.fr/inserm-00808966
DOI : 10.1016/j.bbrc.2013.01.050
PUBMED : 23352615

Éditeur(s) : HAL CCSD IWA Publishing
Résumé : International audience
The widely occurring degradation product aminomethylphosphonic acid (AMPA) is a result of glyphosate and amino-polyphosphonate degradation. Massive use of the parent compounds leads to the ubiquity of AMPA in the environment, and particularly in water. The purpose of this review is to summarize and discuss current insights into AMPA formation, transport, persistence and toxicity. In agricultural soils, AMPA is concentrated in the topsoil, and degrades slowly in most soils. It can reach shallow groundwater, but rarely managed to enter deep groundwater. AMPA is strongly adsorbed to soil particles and moves with the particles towards the stream in rainfall runoff. In urban areas, AMPA comes from phosphonates and glyphosate in wastewater. It is commonly found at the outlets of Wastewater Treatment Plants (WWTP). Sediments tend to accumulate AMPA, where it may be biodegraded. Airborne AMPA is not negligible, but does wash-out with heavy rainfall. AMPA is reported to be persistent and can be biologically degraded in soils and sediments. Limited photodegradation in waters exists. AMPA mainly has its sources in agricultural leachates, and urban wastewater effluents. The domestic contribution to urban loads is negligible. There is a critical lack of epidemiological data - especially on water exposure - to understand the toxicological effects, if any, of AMPA on humans. Fortunately, well operated water treatment plants remove a significant proportion of the AMPA from water, even though there are not sufficient regulatory limits for metabolites.
ISSN: 0043-1354

hal-01516026
https://hal-univ-rennes1.archives-ouvertes.fr/hal-01516026
https://hal-univ-rennes1.archives-ouvertes.fr/hal-01516026/document
https://hal-univ-rennes1.archives-ouvertes.fr/hal-01516026/file/Grandcoin%20et%20al.%20-%20AminoMethylPhosphonic%20acid%20%28AMPA%29%20in%20natural%20water.pdf
DOI : 10.1016/j.watres.2017.03.055

Éditeur(s) : HAL CCSD
Résumé : Publié en septembre 2013 dans le "Journal de Gynécologie Obstétrique et Biologie de la Reproduction" vol.42 n°5 p.413-444
We review the epidemiological literature on the possible impact of chemical and physical factors on pregnancy outcome. Effects of in-utero exposures on child health are not considered here. The highest levels of evidence concern the effects of passive smoking (on fetal growth), of lead (pregnancy-induced hypertension, fetal growth), of some Polychlorinated Biphenyls (PCB; on fetal growth) and, to a lesser extent, of atmospheric pollutants (on fetal growth and preterm delivery). For the other compounds, in particular non-persistent chemicals, the literature, which is generally based on poor exposure assessment, is less informative. In conclusion, the last decades have witnessed the development of mother-child cohorts in which exposure biomarkers have been assayed, allowing a large number of publications. For some persistent compounds, for which efficient exposure assessment approaches have been used, the literature indicates a likely impact on pregnancy outcomes. With the exception of air pollutants, the literature on non-persistent compounds is little conclusive; the assay of exposure biomarkers in repeated biological samples collected at relevant time points could help further increase knowledge regarding any health impact.
https://hal.archives-ouvertes.fr/hal-00916684

hal-00916684
https://hal.archives-ouvertes.fr/hal-00916684
https://hal.archives-ouvertes.fr/hal-00916684/document
DOI : 10.1016/j.jgyn.2013.02.012

Éditeur(s) : PSIC 11 - 11th Pacific Science Inter-Congress : Pacific Countries and their Ocean: Facing Local and Global Changes / 2nd Symposium on French Research in the Pacific. March 2 - 6, 2009 Tahiti, French Polynesia.
Résumé : In recent years the biological control of diseases by environmental friendly methods such as probiotics has become an important subject of investigation in aquaculture research. Probiotics are live microorganisms which when administrated in adequate amounts confer a health benefit on the host . In the last 4 years, IFREMER in collaboration with Lallemand company, have carried out researchs in New Caledonia with the aim to assess the probiotic strain P. acidilactici MA 18/5M on farmed shrimp Litopenaeus stylirostris.This project started in 2005 demonstrated the beneficial effects of the probiotic Pediococcus acidilactici dietary supplementation on the nutrition and the health status of peneid shrimps and highlighted that its use as probiotic can be part of the natural solutions proposed to face the challenge of today’s shrimp farming industry.

Droits : info:eu-repo/semantics/openAccess
http://archimer.ifremer.fr/doc/00197/30873/29241.pdf
http://archimer.ifremer.fr/doc/00197/30873/

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
Co-exposure to environmental polycyclic aromatic hydrocarbons (PAHs) and interleukin (IL)-1β induces expression of the tumor-promoting cytokine IL-6 in cancer cells. The present study was designed to determine whether such an IL-6 up-regulation also occurs in response to co-treatment by PAHs and tumor necrosis factor (TNF)-α, an inflammatory cytokine commonly found in tumor microenvironment. Co-exposure to the prototypical PAH benzanthracene (BZA) and TNF-α was found to markedly induce mRNA expression and secretion of IL-6 in human breast cancer cells MCF-7, whereas exposure to either BZA or TNF-α alone was without significant effect. Co-treatment by BZA and TNF-α-containing conditioned media from human inflammatory macrophages similarly up-regulated IL-6 expression in MCF-7 cells. BZA/TNF-α-mediated IL-6 induction in MCF-7 cells was counteracted by silencing aryl hydrocarbon receptor (AhR), known to mediates most of PAH effects. IL-6 up-regulation was moreover associated with NF-κB activation and was abolished by using chemical NF-κB inhibitors or knocking-down expression of the p65/RelA NF-κB subunit. Taken together, these data indicate that co-exposure to BZA/TNF-α induces IL-6 expression by AhR- and NF-κB-dependent pathways in MCF-7 cancer cells. This regulation of IL-6 by environmental PAHs, that is dependent of inflammatory cytokine microenvironment, may contribute to the well-known carcinogenic properties of these organic pollutants.
ISSN: 0009-2797

inserm-00818896
http://www.hal.inserm.fr/inserm-00818896
DOI : 10.1016/j.cbi.2013.01.005
PUBMED : 23396138

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
Technologies for wireless telecommunication systems using millimeter waves (MMW) will be widely deployed in the near future. Forthcoming applications in this band, especially around 60 GHz, are mainly developed for high data-rate local and body-centric telecommunications. At those frequencies, electromagnetic radiations have a very shallow penetration into biological tissues, making skin keratinocytes, and free nerve endings of the upper dermis the main targets of MMW. Only a few studies assessed the impact of MMW on neuronal cells, and none of them investigated a possible effect on neuronal differentiation. We used a neuron-like cell line (PC12), which undergoes neuronal differentiation when treated with the neuronal growth factor (NGF). PC12 cells were exposed at 60.4 GHz for 24 h, at an incident power density averaged over the cell monolayer of 10 mW/cm2. Using a large scale cell-by-cell analysis based on high-content screening microscopy approach, we assessed potential effects of MMW on PC12 neurite outgrowth and cytoskeleton protein expression. No differences were found in protein expression of the neuronal marker β3-Tubulin nor in internal expression control β-Tubulin. On the other hand, our data showed a slight increase, although insignificant, in neurite outgrowth, induced by MMW exposure. However, experimental controls demonstrated that this increase was related to heating
ISSN: 0304-3940

hal-01281481
https://hal-univ-rennes1.archives-ouvertes.fr/hal-01281481
https://hal-univ-rennes1.archives-ouvertes.fr/hal-01281481/document
https://hal-univ-rennes1.archives-ouvertes.fr/hal-01281481/file/Effects%20of%2060-GHz%20Millimeter%20Waves%20on%20Neurite.pdf
DOI : 10.1016/j.neulet.2016.02.038

Éditeur(s) : HAL CCSD
Résumé : International audience
BACKGROUND: Numerous studies have linked prenatal traffic-related air pollution exposure to fetal growth. Recently, several studies have suggested exploring this association independently among boys and girls because of potential sex-specific biological vulnerability to air pollution. Residence-based factors can also influence fetal growth by enhancing susceptibility to the toxic effects of air pollution and must also be considered in these relations. OBJECTIVE: We examined sex-specific associations between prenatal air pollution exposure and fetal growth and explored whether they differed by the urban-rural status of maternal residence. METHODS: This study relied on the PELAGIE mother-child cohort (2521 women, Brittany, France, 2002-2006). Fetal growth was assessed through birth weight, head circumference and small weight (SGA) and small head circumference (SHC) for gestational age. Nitrogen dioxide (NO2) concentrations at mothers' homes were estimated by using a land use regression model taking into account temporal variation during pregnancy. Associations between estimated NO2 concentrations and fetal growth were assessed with linear regression or logistic regression models, depending on the outcome investigated. RESULTS: An interquartile range (8.8µgm(-3)) increase in NO2 exposure estimates was associated with a 27.4g (95% CI 0.8 to 55.6) increase in birth weight and a 0.09cm (95% CI 0.00-0.17) significant increase in head circumference, among newborn boys only. Their risks of SGA and SHC were reduced (OR 0.70, 95% CI 0.53-0.92, OR 0.76, 95% CI 0.56-1.03, respectively, for an increase of 8.8µgm(-3)). No statistically significant trends were observed among girls. Urban-rural status modified the effect of air pollution only for SHC and again only for newborn boys. CONCLUSION: Findings from this study confirm the need to consider sex-specific associations between air pollution and fetal growth and to investigate possible mechanisms by which traffic-related air pollution may increase anthropometric parameters at birth
Environmental Research

hal-01205354
https://hal-univ-rennes1.archives-ouvertes.fr/hal-01205354
DOI : 10.1016/j.envres.2015.09.006
PUBMED : 26378737

Éditeur(s) : HAL CCSD Public Library of Science
Résumé : International audience
In mutualisms, each interacting species obtains resources from its partner that it would obtain less efficiently if alone, and so derives a net fitness benefit. In exchange for shelter (domatia) and food, mutualistic plant-ants protect their host myrmecophytes from herbivores, encroaching vines and fungal pathogens. Although selective filters enable myrmecophytes to host those ant species most favorable to their fitness, some insects can by-pass these filters, exploiting the rewards supplied whilst providing nothing in return. This is the case in French Guiana for Cecropia obtusa (Cecropiaceae) as Pseudocabima guianalis caterpillars (Lepidoptera, Pyralidae) can colonize saplings before the installation of their mutualistic Azteca ants. The caterpillars shelter in the domatia and feed on food bodies (FBs) whose production increases as a result. They delay colonization by ants by weaving a silk shield above the youngest trichilium, where the FBs are produced, blocking access to them. This probable temporal priority effect also allows female moths to lay new eggs on trees that already shelter caterpillars, and so to occupy the niche longer and exploit Cecropia resources before colonization by ants. However, once incipient ant colonies are able to develop, they prevent further colonization by the caterpillars. Although no higher herbivory rates were noted, these caterpillars are ineffective in protecting their host trees from a pathogenic fungus, Fusarium moniliforme (Deuteromycetes), that develops on the trichilium in the absence of mutualistic ants. Therefore, the Cecropia treelets can be parasitized by two often overlooked species: the caterpillars that shelter in the domatia and feed on FBs, delaying colonization by mutualistic ants, and the fungal pathogen that develops on old trichilia. The cost of greater FB production plus the presence of the pathogenic fungus likely affect tree growth.
PLoS ONE

hal-00912399
https://hal.archives-ouvertes.fr/hal-00912399
https://hal.archives-ouvertes.fr/hal-00912399/document
DOI : 10.1371/journal.pone.0020538
OATAO : 10156

Résumé : L’ingénierie agroécologique vise à produire des savoirs actionnables, pour concevoir des systèmes de cultures économiquement et écologiquement performants, par la valorisation de régulations naturelles. Notre problématique est centrée sur la santé des cultures, et plus particulièrement sur la bactérie phytopathogène Ralstonia solanacearum, agent du flétrissement bactérien alors qu’une souche extrêmement agressive menace la production de tomates en plein champ en Martinique. La nécessité d’explorer et de développer des alternatives aux méthodes conventionnelles de protection des plantes (variétés résistantes, pesticides), actuellement inefficaces, invite à la mise en œuvre d’une démarche de conception innovante. Nos travaux montrent que la mobilisation d’une barrière rhizosphérique est une stratégie de régulation biologique alternative. Différents processus y contribuent, telle que la mycorhization, symbiose entre racines et champignons mycorhiziens à arbuscules, présents dans la plupart des sols. Nous montrons que la mobilisation de réseaux de mycorhizes indigènes à partir d’un sol agricole permet une mycorhization précoce de la tomate. De plus, l’association de plantes aux propriétés mycorhizotrophes et assainissantes en conditions contrôlées montre des effets bioprotecteurs partiels et ouvre de nouvelles perspectives de combinaisons entre processus. Ces combinaisons sont mobilisables par des leviers d’actions multi-scalaires. Nous avons produit une grille d’analyse générique de ces leviers d’action pour la conception, par des trajectoires d’innovation multidirectionnelles, de « systèmes de culture bioprotégés ». Dans le contexte agricole martiniquais, une démarche d’apprentissage permet en effet l’émergence d’une dynamique de co-conception de systèmes de cultures recourant aux plantes mycorhizotrophes. Nos travaux proposent des outils pour une exploration collective de nouvelles stratégies de gestion durable de la santé des cultures.
Agroecological engineering aims to produce actionable knowledge to design economically and environmentally efficient cropping systems, based on the exploitation of natural regulation mechanisms. Our issue is centered on crop health, especially on the plant pathogenic bacterium Ralstonia solanacearum (bacterial wilt agent), of which an extremely aggressive strain threatens field tomato production in Martinique. The need to explore and develop alternatives to conventional methods of plant protection (resistant varieties, pesticides), ineffective in our case, calls for the implementation of an innovative design approach. Our work shows that the protection of the roots via the formation of a self-sustaining rhizospheric barrier may be an alternative biological control strategy. Different processes contribute, such as mycorrhizal symbiosis between roots and arbuscular mycorrhizal fungi, which are present in most soils. We show that the mobilization of indigenous mycorrhizal networks from an agricultural soil allows early mycorrhization of tomatoes. In addition, the association of plants with mycorrhizal and sanitizing properties in controlled conditions showed partial bioprotective effects and opens up new prospects for combinations between processes. These combinations may be exploited in various ways. We produced a generic analysis grid of key levers to design "healthy cropping systems " through multi-directional innovation trajectories. In Martinique's agricultural context, a learning process allows the emergence of a dynamic co-design of cropping systems using mycorrhizal plants. Our work thus provides tools for collective exploration of new sustainable management strategies for crop health.

http://www.theses.fr/2015AGUY0828/document

Éditeur(s) : HAL CCSD Springer
Résumé : International audience
One of the most important topics that occupy public health problems is the air quality. That is the reason why mechanical ventilation and air handling units (AHU) were imposed by the different governments in the collective or individual buildings. Many buildings create an artificial climate using heating, ventilation and airconditioning (HVAC) systems. Among the existing aerosols in the indoor air, we can distinguish the bioaerosol with biological nature such as bacteria, viruses, fungi. Respiratory viral infections are a major public health issue because they are usually highly infective. We spend about 90% of our time in closed environments such as homes, workplaces or transport. Some studies have shown that AHU contribute to the spread and transport of viral particles within buildings. The aim of this work is to study the characterization of viral bioaerosols in indoor environments and to understand the fate of mengovirus eukaryote RNA virus on glass fiber filter F7 used in AHU. In this study, a setup close to reality of AHU system was used. The mengovirus aerosolized was characterized and measured with the Electrical Low Pressure Impact (ELPI) and the Scanner Mobility Particle Size (SMPS) and detected with RT-qPCR. The results about quantification and the level of infectivity of mengovirus on the filter and in the biosampler showed that mengovirus can pass through the filter and remain infectious upstream and downstream the system. Regarding the virus effectiveness on the filter under a constant air flow, and mengovirus was remained infectious during 10 hours after aerosolization.
ISSN: 1867-0334

hal-01636427
https://hal-univ-rennes1.archives-ouvertes.fr/hal-01636427
https://hal-univ-rennes1.archives-ouvertes.fr/hal-01636427/document
https://hal-univ-rennes1.archives-ouvertes.fr/hal-01636427/file/Fate%20of%20mengovirus%20on%20fiberglass%20filter_accepted.pdf
DOI : 10.1007/s12560-017-9310-8

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
The estrogen receptor (ER) is a transcription factor that binds under 17-b-estradiol (E2) stimulation as homodimer to a short DNA consensus sequence named estrogen response element (ERE). The ER/ERE interaction has been assessed by several research groups through different methodologies notably by surface plasmon resonance (SPR) techniques. The biochemical parameters and conditions (solvent, ER concentration, salt, time and temperature) used to prepare samples before analysis were very different from one study to another. But no studies have aimed to compare the effect of these modifications on ER/ERE interaction. Therefore the main objective of the present paper was to assess the influence of biochemical parameters onto the ER/ERE interaction with the final aim to improve the comprehension of this interaction. Our results highlighted that parameters like solvent, ER concentration, salt and surfactant concentration, temperature and time deeply modify ER/ERE interaction. Nevertheless, the dimer formation under E2 stimulation occurred with all tested conditions. Altogether, incubation parameters of ER with E2, deeply modify its binding level onto ERE. These data constitute an important key point to consider for the improvement of ER/ERE detection method depending upon the aim of the study (interaction measurement, environmental detection, development of new technologies or devices).
ISSN: 0003-9861

hal-00936061
https://hal.archives-ouvertes.fr/hal-00936061
https://hal.archives-ouvertes.fr/hal-00936061/document
https://hal.archives-ouvertes.fr/hal-00936061/file/Impactsur biochemical_design_on_estrogen_receptor_estrogen_response_element_interaction_by_surface_plasmon_resonance_technology-accepted.pdf
DOI : 10.1016/j.abb.2013.11.006

Éditeur(s) : Pergamon-elsevier Science Ltd
Résumé : Shrimp farming in New Caledonia typically uses a flow-through system with water exchange rates as a tool to maintain optimum hydrological and biological parameters for the crop. Moreover, the effluent shows hydrobiological characteristics (minerals, phytoplankton biomass and organic matter) significantly higher than that of the receiving environment. Separate surveys were carried out in a bay (CH Bay) with a medium-size intensive farm (30 ha) (PO) and in a mangrove-lined creek (TE Creek) near a larger semi-intensive farm (133 ha) (SO). Net loads of nitrogen exported from the semi-intensive farm and the intensive farm amounted to 0.68 and 1.36 kg ha(-1) day(-1), respectively. At CH Bay, discharge effects were spatially limited and clearly restricted to periods of effluent release. The high residence time at site TE favoured the installation of a feedback system in which organic matter was not exported. Mineralization of organic matter led to the release of nutrients, which in turn, caused in an increased eutrophication of this ecosystem. The study of the pico- and nanophytoplankton assemblages showed (i) a shift in composition from picophytoplankton to nanophytoplankton from offshore towards the coast and (ii) a shift within the picophytoplankton with the disappearance of Prochlorococcus and the increase of picoeucaryotes towards the shoreline. These community changes may partially be related to a nitrogen enrichment of the environment by shrimp farm discharges. Thus, in view of the recent addition of the New Caledonian lagoon to the UNESCO World Heritage list, the data presented here could be a first approach to quantify farm discharges and evaluate their impact on the lagoon. (C) 2010 Elsevier Ltd. All rights reserved.
Marine Pollution Bulletin (0025-326X) (Pergamon-elsevier Science Ltd), 2010 , Vol. 61 , N. 7-12 , P. 387-398

Droits : 2010 Elsevier Ltd All rights reserved.
http://archimer.ifremer.fr/doc/00014/12527/9882.pdf
DOI:10.1016/j.marpolbul.2010.07.005
http://archimer.ifremer.fr/doc/00014/12527/

Éditeur(s) : HAL CCSD
Résumé : The spectrin-based skeleton is an essential scaffold underlying different lipid bilayers in all animal cells. Spectrins (Sp), as giant extended flexible heterotetramers (αβ)2, constitute the filaments of this network, the nodes of which are cross-linked by actin filaments. The functions of the Sp-based skeleton, which are well defined in red blood cells (required for shape, resistance to shear stress and deformability) are less well understood in non-erythroid cells.The non-erythroid Sp might participate in the establishment and/or the maintenance of specialized membrane subdomains by accumulating integral membrane proteins (such as ionic channels, ionic pumps, receptors and cell adhesion molecules) as revealed by loss of the main non-erythroid β-Sp. However the effect of non-erythroid α-Sp are less well established. In mammals, α-Sp are encoded by two genes: one for αI-Sp mainly expressed in mature erythrocyte, the second one for αII-Sp which is expressed in all nucleated cells.In the pursuit of αII-Sp functions, we have checked the effect of αII-Sp knock down by siRNA melanoma human cell line. Our data revealed that spectrin depletion is associated with i) an arrest of cell cycle at G1 state ii) a loss of cell adhesion in spite of increase in some integrins iii) some modifications of actin organisation.
Le squelette dépendant de la spectrine, localisé sous la bicouche lipidique, est un échafaudage essentiel de toutes les cellules animales. La Spectrine (Sp), structure géante, robuste mais flexible d'hétéro tétramères (αβ)2, constitue les filaments de ce réseau, dont chaque nœud interagit avec des filaments d'actine. Les fonctions du squelette de Sp, qui sont bien définies dans le globule rouge (rôle dans sa forme, dans sa résistance aux forces de cisaillement et dans sa déformabilité) sont moins bien connues dans les cellules non-érythroïdes. La Sp non-érythroïde pourrait participer à l'établissement et/ou au maintien de sous-domaines membranaires spécialisés dans l'accumulation de protéines de membrane (telles que les canaux ioniques, les pompes ioniques, les récepteurs et les molécules d'adhérence) comme nous le font penser les invalidations de la Sp-β non-érythroïde. Cependant le rôle de la Sp-α non-érythroïde est moins bien établi. Chez les mammifères, la Sp-α est codée par deux gènes: un pour Sp-αI, principalement exprimée dans l'érythrocyte mature, le second pour Sp-αII qui est exprimée dans toutes les cellules nucléées. Pour étudier les fonctions de la Sp-αII, nous avons utilisé une approche de SiRNA sur des cellules de mélanome humain. Nos données montrent que la diminution de Sp-αII est associée à I) un arrêt en G1 du cycle cellulaire II) une perte d'adhérence des cellules malgré l'augmentation de quelques intégrines III) des modifications dans l'organisation du réseau d'actine.
https://tel.archives-ouvertes.fr/tel-00377569

Droits : info:eu-repo/semantics/OpenAccess
tel-00377569
https://tel.archives-ouvertes.fr/tel-00377569
https://tel.archives-ouvertes.fr/tel-00377569/document
https://tel.archives-ouvertes.fr/tel-00377569/file/these_210409_entiere.pdf
https://tel.archives-ouvertes.fr/tel-00377569/file/II-Spectrin_Is_Critical_for_Cell_Adhesion_and_Cell_Cycle.PDF

Éditeur(s) : HAL CCSD
Résumé : International audience
Estrogens affect brain development of vertebrates, not only by impacting activity and morphology of existing circuits, but also by modulating embryonic and adult neurogenesis. The issue is complex as estrogens can not only originate from peripheral tissues, but also be locally produced within the brain itself due to local aromatization of androgens. In this respect, teleost fishes are quite unique because aromatase is expressed exclusively in radial glial cells, which represent pluripotent cells in the brain of all vertebrates. Expression of aromatase in the brain of fish is also strongly stimulated by estrogens and some androgens. This creates a very intriguing positive auto-regulatory loop leading to dramatic aromatase expression in sexually mature fish with elevated levels of circulating steroids. Looking at the effects of estrogens or anti-estrogens in the brain of adult zebrafish showed that estrogens inhibit rather than stimulate cell proliferation and newborn cell migration. The functional meaning of these observations is still unclear, but these data suggest that the brain of fish is experiencing constant remodeling under the influence of circulating steroids and brain-derived neurosteroids, possibly permitting a diversification of sexual strategies, notably hermaphroditism. Recent data in frogs indicate that aromatase expression is limited to neurons and do not concern radial glial cells. Thus, until now, there is no other example of vertebrates in which radial progenitors express aromatase. This raises the question of when and why these new features were gained and what are their adaptive benefits. This article is part of a Special Issue entitled: Nuclear receptors in animal development.
Biochimica et Biophysica Acta (BBA) - Gene Regulatory Mechanisms

Droits : info:eu-repo/semantics/OpenAccess
hal-01102449
https://hal.archives-ouvertes.fr/hal-01102449
https://hal.archives-ouvertes.fr/hal-01102449/document
https://hal.archives-ouvertes.fr/hal-01102449/file/Coumailleau%20et%20al%20final%20manuscript.pdf
DOI : 10.1016/j.bbagrm.2014.07.002

Éditeur(s) : HAL CCSD
Résumé : The forests of French Guiana occupy a central part of the region’s potential resource base, but as yet remain almost completely unexploited. This stems from the forestry industry struggling to valorize wood stocks of a high diversity with an extremely heterogeneous distribution. Indeed, identifying essences for future propagation is an issue of both environmental and socio-economic importance for the region. Bagassa guianensis Aubl. and Cordia alliodora (Ruiz & Pav.) Oken. go against conventional models, in that they display the life history characteristics of rapid growth and wood of high quality, and thus are species of high potential for future plantations. Firstly, our study of growth characteristics reveals a defined strategy half way between long-lived species and pioneer species. It is the variability of basic density of wood which is a key trait allowing for such a development, favoring rapid growth in initial years whilst allowing for tree longevity. Secondly, the analysis of a range of wood properties (shrinkage, modulus of elasticity, durability) in relation to tree growth confirms the technologic quality of the two species. It also enables the emergence of new results like the effect of extractives on wood stability, the control of growth as a result of basic density variation, the evolution of leaf traits throughout tree development or the improvement of trunk maintenance thanks to interlocked grain. The knowledge gained in relation to the developmental traits of these two species, and to the quality of their wood allows for the elaboration of plantation projects and what will be required for their success. The results of this study can orientate future studies on novel species for commercialization in French Guiana.
La ressource forestière en Guyane occupe une place maîtresse au sein de la région et est encore majoritairement préservée, mais la filière bois parvient difficilement à valoriser la biodiversité locale en raison de l’hétérogénéité de la ressource. Identifier les essences à planter demain représente aujourd’hui un enjeu à la fois environnemental, économique et social pour la Guyane. Bagassa guianensis Aubl. et Cordia alliodora (Ruiz & Pav.) Oken. vont à l’encontre des modèles usuels en associant vitesse de croissance et qualité du bois et sont identifiées comme prometteuses pour la plantation. Dans un premier temps, l’étude de la dynamique de croissance des deux espèces révèle un modèle écologique singulier, à la fois pionnières et longévives. La variabilité de l’infradensité dans l’arbre est l’élément clé qui permet un tel développement, favorisant une croissance rapide dans les premières années tout en assurant la longévité de l’individu. Dans une seconde partie, l’analyse d’un large panel de propriétés du bois (retrait, module, durabilité) en lien avec le développement de l’arbre confirme les qualités technologiques des deux espèces et permet l’émergence de résultats novateurs tels que le rôle des extractibles sur le retrait, le contrôle de la croissance grâce aux variations d’infradensité, l’évolution des traits foliaires au cours de l’ontogénie ou encore la mise en place de contrefil dans l’arbre pour assurer son maintien. La connaissance acquise vis-à-vis du mode de développement de ces deux espèces et des facteurs influençant la qualité de leur bois permet aujourd’hui de définir avec plus de précision le cadre d’un projet de plantation et les conditions de son succès. Les résultats de cette étude permettent finalement d’orienter la recherche de nouvelles espèces d’avenir pour la plantation en Guyane.
https://tel.archives-ouvertes.fr/tel-01338281

tel-01338281
https://tel.archives-ouvertes.fr/tel-01338281
https://tel.archives-ouvertes.fr/tel-01338281/document
https://tel.archives-ouvertes.fr/tel-01338281/file/Th%C3%A8se%20Julie%20Bossu.pdf

Éditeur(s) : HAL CCSD Wiley/Blackwell
Résumé : Whole genome sequencing is helping generate robust phylogenetic hypotheses for a range of taxonomic groups that were previously recalcitrant to classical molecular phylogenetic approaches. As a case study, we performed a shallow shotgun sequencing of eight species in the tropical tree family Chrysobalanaceae to retrieve large fragments of high-copy number DNA regions and test the potential of these regions for phylogeny reconstruction. We were able to assemble the nuclear ribosomal cluster (nrDNA), the complete plastid genome (ptDNA) and a large fraction of the mitochondrial genome (mtDNA) with approximately 1000x, 450x and 120x sequencing depth respectively. The phylogenetic tree obtained with ptDNA resolved five of the seven internal nodes. In contrast, the tree obtained with mtDNA and nrDNA data were largely unresolved. This study demonstrates that genome skimming is a cost-effective approach and shows potential in plant molecular systematics within Chrysobalanaceae and other under-studied groups.
ISSN: 1755-098X

hal-01204217
https://hal.archives-ouvertes.fr/hal-01204217
DOI : 10.1111/1755-0998.12246
PRODINRA : 283530

Éditeur(s) : HAL CCSD Public Library of Science
Résumé : International audience
Little information exists on the effects of ocean acidification (OA) on the digestive and post-digestive processes in marine fish. Here, we investigated OA impacts (Δ pH = 0.5) on the trophic transfer of select trace elements in the clownfish Amphiprion ocellaris using radiotracer techniques. Assimilation efficiencies of three essential elements (Co, Mn and Zn) as well as their other short-term and long-term kinetic parameters in juvenile clownfish were not affected by this experimental pH change. In complement, their stomach pH during digestion were not affected by the variation in seawater pH. Such observations suggest that OA impacts do not affect element assimilation in these fish. This apparent pCO2 tolerance may imply that clownfish have the ability to self-regulate pH shifts in their digestive tract, or that they can metabolically accommodate such shifts. Such results are important to accurately assess future OA impacts on diverse marine biota, as such impacts are highly species specific, complex, and may be modulated by species-specific metabolic processes.
ISSN: 1932-6203

hal-01564009
https://hal-univ-perp.archives-ouvertes.fr/hal-01564009
https://hal-univ-perp.archives-ouvertes.fr/hal-01564009/document
https://hal-univ-perp.archives-ouvertes.fr/hal-01564009/file/trophic%20transfer.pdf
DOI : 10.1371/journal.pone.0174344

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
The present study investigated cerebral and muscle hemoglobin oxygen saturation (tissue oxygen index, TOI) in children with sickle cell anemia (SS), sickle cell hemoglobin C disease (SC) and healthy children (AA). TOI was measured by near-infrared spectroscopy (NIRS) and spectral analysis of the TOI variability was used to assess flowmotion and vasomotion. Arterial oxyhemoglobin saturation (SpO2), hemorheological and hematological parameters were also measured in SS and SC children. Both TOI were lower in SS compared to both AA and SC children, with SC exhibiting lower values than AA children. Cerebral vasomotion expressed in absolute values was enhanced in SS compared to AA and SC children. Muscle vasomotion did not differ between the three groups. Hematocrit, SpO2 and red blood cell deformability were positively associated with cerebral TOI in SS children. We demonstrated that 1) cerebral and muscle TOI were markedly decreased in SS children while the decrease of TOI was milder in SC children, 2) cerebral TOI level was associated with several biological markers in SS children only and 3) cerebral vasomotion was enhanced in SS, possibly to counterbalance the effects of chronic cerebral hypoxia.
ISSN: 1079-9796

hal-01668321
https://hal.univ-antilles.fr/hal-01668321
DOI : 10.1016/j.bcmd.2017.03.015