Éditeur(s) : HAL CCSD Society for the Study of Reproduction
Résumé : International audience
Matrix-assisted laser desorption/ionization (MALDI) tissue imaging mass spectrometry is particularly promising among the numerous applications of mass spectrometry. It is used for probing and analyzing the spatial arrangement of a wide range of molecules, including proteins, peptides, lipids, drugs, and metabolites, directly in thin slices of tissue. In the field of proteomics, the technology avoids tedious and time-consuming extraction and fractionation steps classically required for sample analysis. MALDI imaging mass spectrometry is increasingly recognized as a powerful method for clinical proteomics, particularly in cancer research. The technology has particular potential for the discovery of new tissue biomarker candidates, classification of tumors, early diagnosis or prognosis, elucidating pathogenesis pathways, and therapy monitoring. Over recent years, MALDI imaging mass spectrometry has been used for molecular profiling and imaging directly in male and female reproductive tissues. This review will consider some of the recent publications in the field, addressing a range of issues covering embryo development, gene expression product profiling during gametogenesis, and seeking and identifying biomarkers of reproductive cancers. The wealth of advances in mass spectrometry imaging will inevitably attract biologists and clinicians as the advantages and power of this technology become more widely known. This review will also discuss bottlenecks and the many technical issues that remain to be resolved before laboratories in the field can adopt the technology. We foresee that MALDI imaging mass spectrometry will have a major impact in reproductive research by opening new avenues to the understanding of various molecular mechanisms and the diagnosis of reproductive pathologies.
ISSN: 0006-3363

hal-00877851
https://hal.archives-ouvertes.fr/hal-00877851
DOI : 10.1095/biolreprod.111.094896
PUBMED : 22156474

Éditeur(s) : HAL CCSD Wiley
Résumé : International audience
Among the environmental threats to coral reef health, temperature and ultraviolet increases have been proposed as major agents, although the relative contribution of each in the cnidarian/zooxanthellae symbiosis breakdown has been poorly addressed. We have investigated the transcriptomic response to thermal stress, with and without ultraviolet radiation (UVR), in the symbiotic sea anemone Anemonia viridis. Using the Oligo2K A.similar to viridis microarray, dedicated to genes potentially involved in the symbiosis interaction, we monitored the gene expression profiles after 1, 2 and 5 days of stresses that further lead to massive losses of zooxanthellae. Each stress showed a specific gene expression profile with very little overlap. We showed that the major response to thermal stress is immediate (24 h) but returns to the baseline gene expression profile after 2 days. UVR alone has little effect but potentiates thermal stress, as a second response at 5 days was observed when the two stresses were coupled. Several pathways were highlighted, such as mesoglea loosening, cell death and calcium homeostasis and described in more details. Finally, we showed that the dermatopontin gene family, potentially involved in collagen fibrillogenesis, issued from actinarian-specific duplication events, with one member preferentially expressed in the gastroderm and specifically responding to stress.
ISSN: 0962-1083

hal-01546174
https://hal.archives-ouvertes.fr/hal-01546174
DOI : 10.1111/j.1365-294X.2012.05458.x

Éditeur(s) : HAL CCSD Elsevier Masson
Résumé : International audience
Millimetre waves correspond to the range of frequencies located between 30 and 300 GHz. Many applications exist and are emerging in this band, including wireless telecommunications, imaging and monitoring systems. In addition, some of these frequencies are used in therapy in Eastern Europe, suggesting that interactions with the human body are possible. This review aims to summarise current knowledge on interactions between millimetre waves and living matter. Several representative examples from the scientific literature are presented. Then, possible mechanisms of interactions between millimetre waves and biological systems are discussed.
ISSN: 1631-0705

hal-00874362
https://hal.archives-ouvertes.fr/hal-00874362
DOI : 10.1016/j.crhy.2013.02.005

Éditeur(s) : HAL CCSD
Résumé : International audience
This study assessed the usefulness of UV spectrophotometry for the monitoring of a yeast-based deoxygenation process proposed for ships' ballast water treatment to prevent the transfer of aquatic invasive species. Ten-day laboratory experiments using three treatment concentrations and different water types were conducted and resulted in complete oxygen depletion of treated waters. The treatment performance and quality of treated waters were determined by measuring the UV-visible absorbance spectra of water samples taken over time. Samples were also used for laboratory analysis of water quality properties. The UV absorbance spectra values were strongly correlated (r = 0.96) to yeast cell density in treated waters. The second-order derivative (D (2)) of the spectra varied greatly over time, and the spectrum profiles could be divided into two groups corresponding to the oxygenated and anoxic phases of the treatment. The D (2) value at 215 nm was strongly correlated (r = 0.94) to ammonia levels, which increased over time. The D (2) value at 225 nm was strongly correlated (r  extgreater 0.97) to DO concentration. Our results showed that UV spectrophotometry may provide a rapid assessment of the behavior and performance of the yeast bioreactor over time by quantifying (1) the density of yeast cells, (2) the time at which anoxic conditions were reached, and (3) a water quality index of the treated water related to the production of ammonia. We conclude that the rapidity of the technique confers a solid advantage over standard methods used for water quality analysis in laboratory and would permit the direct monitoring of the treatment performance on-board ships
Environmental Monitoring and Assessment

hal-01286253
https://hal-univ-rennes1.archives-ouvertes.fr/hal-01286253
DOI : 10.1007/s10661-016-5209-3
PUBMED : 26944435

Éditeur(s) : HAL CCSD Royal Society, The
Résumé : International audience
To forecast marine disease outbreaks as oceans warm requires new environmental surveillance tools. We describe an iterative process for developing these tools that combines research, development and deployment for suitable systems. The first step is to identify candidate host–pathogen systems. The 24 candidate systems we identified include sponges, corals, oysters, crustaceans, sea stars, fishes and sea grasses (among others). To illustrate the other steps, we present a case study of epizootic shell disease (ESD) in the American lobster. Increasing prevalence of ESD is a contributing factor to lobster fishery collapse in southern New England (SNE), raising concerns that disease prevalence will increase in the northern Gulf of Maine under climate change. The lowest maximum bottom temperature associated with ESD prevalence in SNE is 128C. Our seasonal outlook for 2015 and long-term projections show bottom temperatures greater than or equal to 128C may occur in this and coming years in the coastal bays of Maine. The tools presented will allow managers to target efforts to monitor the effects of ESD on fishery sustainability and will be iteratively refined. The approach and case example highlight that temperature-based surveillance tools can inform research, monitoring and management of emerging and continuing marine disease threats.
ISSN: 0080-4622

Droits : http://creativecommons.org/licenses/by/
hal-01282834
https://hal-univ-perp.archives-ouvertes.fr/hal-01282834
https://hal-univ-perp.archives-ouvertes.fr/hal-01282834/document
https://hal-univ-perp.archives-ouvertes.fr/hal-01282834/file/20150208.full.pdf
DOI : 10.1098/rstb.2015.0208

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
Archival Pneumocystis jirovecii specimens from 84 patients monitored at Rennes University Hospital (Rennes, France) were assayed at the dihydropteroate synthase (DHPS) locus. No patient was infected with mutants. The results provide additional data showing that P. jirovecii infections involving DHPS mutants do not represent a public health issue in Brittany, western France.
ISSN: 0732-8893

hal-00874675
https://hal.archives-ouvertes.fr/hal-00874675
DOI : 10.1016/j.diagmicrobio.2013.01.018
PUBMED : 23433532

Éditeur(s) : HAL CCSD Laboratoire Arago
Résumé : International audience
Some coral reefs are threatened around the world due to the effects of coastaldevelopment, over-fishing and multiple factors associated with global climate change. In 2013,a monitoring programme was implemented in Western Samoa to document changes in reef communitiesand the impacts of natural and anthropogenic disturbances. Underwater visual surveysreported the first data on coral cover on the north coast of Western Samoa. Between 2013 and2015, all living coral genera (Acropora, Leptoria, Montipora, Platygyra, Pocillopora) droppedfrom 42 % to 0 %. The interaction of crown-of-thorns startfish outbreak in 2010-2014 andunusually high temperature in 2015 could have acted as a deathly combination for the coralreefs in Western Samoa.
ISSN: 0240-8759

hal-01416776
https://hal-univ-perp.archives-ouvertes.fr/hal-01416776

Éditeur(s) : HAL CCSD
Résumé : International audience
Traffic air pollution is a major health problem and is recognized as an important risk factor for cardiovascular disease. Even so the role of particles-induced adverse health effects is well established, recent studies outlined the contribution of nitrogen dioxide (NO2) in these effects, in particular on the cardiovascular function. The main sources of this pollutant are oxidation catalysts used to reduce emissions of carbon monoxide and non-methane hydrocarbons from the exhaust of diesel engines and also to facilitate filter regeneration. However, the contribution of NO2 compared to other gaseous and particulate pollutants remains unknown. Consequently, the main objective of this study was to analyze the specific contributions of NO2 in the traffic-related air pollution-induced cardiovascular adverse effects. For this, Wistar rats were exposed for 3 weeks (3h/day, 5 days/week) to either a continuous flow of catalyzed diesel exhaust (DE), particle free or whole DE (particles concentration 2mg/m3), either to a continuous flow of NO2 used at a concentration identical to that measured in the exhaust line. The composition of the emission and the NO2 analyses were monitored on-line during the whole experiment. We evaluated cardiac function and biological effects after 16h recovery in clean air. DE or NO2 exposures induced a modest cardiac dysfunction characterized by an increase in left ventricular diameters and a decrease in fractional shortening. In the case of DE, the presence of particles did not worsen the impairment of cardiac function. In parallel to this effect, mitochondrial function was altered as illustrated by the reduction of the oxygen consumption and of the ATP production. Mitochondrial reactive oxygen species was increased only by the NO2 exposure. In conclusion, these results suggest that DE-induced cardiac dysfunction is due to, at least in part, to NO2 present in DE.
Archives of Cardiovascular Diseases Supplements
Toulouse, France

hal-01150495
https://hal-univ-rennes1.archives-ouvertes.fr/hal-01150495
DOI : 10.1016/S1878-6480(15)30036-7

Éditeur(s) : HAL CCSD European Geosciences Union
Résumé : International audience
The exchanges of carbon, water and energy between the atmosphere and the Amazon basin have global implications for the current and future climate. Here, the global atmospheric inversion system of the Monitoring of Atmospheric Composition and Climate (MACC) service is used to study the seasonal and interannual variations of biogenic CO 2 fluxes in Amazonia during the period 2002–2010. The system assimilated surface measurements of atmospheric CO 2 mole fractions made at more than 100 sites over the globe into an atmospheric transport model. The present study adds measurements from four surface stations located in tropical South America, a region poorly covered by CO 2 observations. The estimates of net ecosystem exchange (NEE) optimized by the inversion are compared to an independent estimate of NEE upscaled from eddy-covariance flux measurements in Amazonia. They are also qualitatively evaluated against reports on the seasonal and interannual variations of the land sink in South America from the scientific literature. We attempt at assessing the impact on NEE of the strong droughts in 2005 and 2010 (due to severe and longer-than-usual dry seasons) and the extreme rainfall conditions registered in 2009. The spatial variations of the seasonal and in-terannual variability of optimized NEE are also investigated. While the inversion supports the assumption of strong spatial heterogeneity of these variations, the results reveal critical limitations of the coarse-resolution transport model, the surface observation network in South America during the recent years and the present knowledge of modelling uncertainties in South America that prevent our inversion from capturing the seasonal patterns of fluxes across Amazonia. However, some patterns from the inversion seem consistent with the anomaly of moisture conditions in 2009.
ISSN: 1680-7316

hal-01557375
https://hal.univ-lorraine.fr/hal-01557375
https://hal.univ-lorraine.fr/hal-01557375/document
https://hal.univ-lorraine.fr/hal-01557375/file/acp-15-8423-2015.pdf
DOI : 10.5194/acp-15-8423-2015-supplement

Résumé : 2005 results of the analysis of the metal and organic contaminants on the flesh of mussels introduced in the port of Goury and in the Moulinets cove in November 2004 and August 2005. The situation is stable compared to the previous years. We observed concentrations of mercury higher than the national medians, although not crossing above the administrative threshold for mercury.
Résultats 2005 des analyses de contaminants métalliques et organiques sur la chair des moules implantées au port de Goury et à l'Anse des Moulinets en novembre 2004 et août 2005. La situation est stable par rapport aux années précédentes. Nous observons des concentrations en mercure supérieures aux médianes nationales, sans dépasser pour autant le seuil administratif pour le mercure.

Droits : info:eu-repo/semantics/openAccess
http://archimer.ifremer.fr/doc/2006/rapport-6371.pdf
http://archimer.ifremer.fr/doc/00000/6371/

Éditeur(s) : HAL CCSD Public Library of Science
Résumé : International audience
Cytomegalovirus (CMV) infection is common among HIV-infected patients but its repercussion on the course of CD4+ and CD8+ T cells after cART initiation remains elusive. The French Dat'AIDS cohort enrolled 5,688 patients on first-line cART, from which we selected patients who achieved HIV suppression for at least 12 months without modification of cART, and for whom CMV serostatus was available. Five hundred and three patients fulfilled the selection criteria (74% male, median age 43 yrs, 15.5% CDC stage C), of whom 444 (88.3%) were seropositive for CMV (CMV+). Multivariate analyses using mixed-linear models adjusted for the time from HIV suppression, sex, age, transmission risk group, duration of HIV follow-up, the interaction between time from HIV suppression and CMV+ serol-ogy, and the nadir CD4 count revealed a negative correlation between CMV+ and CD4: CD8 ratio (coeff. =-0.16; p = 0.001). This correlation was also observed among patients displaying optimal CD4 recovery (!500 cells/mm3 at M12; coeff. =-0.24; p = 0.002). Hence, CMV+ serostatus antagonizes normalization of the CD4:CD8 ratio, although further analyses of the impact of co-morbidities that associate with CMV serostatus, like HCV infection, are needed to elucidate this antagonism formally. However, this might reflect a premature T cell senescence, thus advocating for a close monitoring of T cells in CMV co-infected patients. In addition, our results raise the question of the benefit of treatment for asymptomatic CMV co-infection in HIV-infected patients.
ISSN: 1932-6203

inserm-01418700
http://www.hal.inserm.fr/inserm-01418700
http://www.hal.inserm.fr/inserm-01418700/document
http://www.hal.inserm.fr/inserm-01418700/file/journal.pone.0165774.PDF
DOI : 10.1371/journal.pone.0165774

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
Clostridium difficile infection (CDI) is the primary cause of nosocomial diarrhoea in industrialised countries, usually occurring as a complication of antibiotic therapy in elderly patients. Landmark events contributed to boosting interest in CDI over the last 10 years, including the emergence of unusually severe and recurrent CDI due to the NAP1/BI/027 strain, as well as reports suggesting that CDI is also significantly encountered in patients previously considered at no risk, such as community-acquired CDI in patients with no recent antibiotic use, or CDI during pregnancy. Despite this growing interest from the medical community, we do not know the real dimensions of the disease for the following reasons: (i) despite comprehensive guidelines published in Europe and in the USA, most laboratories still use diagnostic tests with suboptimal sensitivity as a 'rule-out' test, hence a significant proportion of CDIs remain undiagnosed; (ii) use of PCR as a stand-alone test by others will probably overestimate the real incidence of CDI and jeopardise any comparison between institutions with different diagnostic procedures; and (iii) transversal studies, with optimum design and diagnostic tests, are rapidly outdated due to the dramatic changes in CDI epidemiology that may occur from one year to another. To get an accurate picture of the real dimensions of the CDI issue, we need more systematic use of an adequate and homogeneous diagnostic strategy in the field as well as the implementation of continuous monitoring of CDI incidence through surveillance programmes.
ISSN: 0924-8579

inserm-00863350
http://www.hal.inserm.fr/inserm-00863350
http://www.hal.inserm.fr/inserm-00863350/document
http://www.hal.inserm.fr/inserm-00863350/file/Clostridium_difficile_infections._Do_we_know_the_real_dimensionssur the_problem-accepted.pdf
DOI : 10.1016/j.ijantimicag.2013.04.009

Éditeur(s) : HAL CCSD Public Library of Science
Résumé : International audience
Establishing a direct link between climate change and fluctuations in animal populations through long-term monitoring is difficult given the paucity of baseline data. We hypothesized that social wasps are sensitive to climatic variations, and thus studied the impact of ENSO events on social wasp populations in French Guiana. We noted that during the 2000 La Niña year there was a 77.1% decrease in their nest abundance along ca. 5 km of forest edges, and that 70.5% of the species were no longer present. Two simultaneous 13-year surveys (1997-2009) confirmed the decrease in social wasps during La Niña years (2000 and 2006), while an increase occurred during the 2009 El Niño year. A 30-year weather survey showed that these phenomena corresponded to particularly high levels of rainfall, and that temperature, humidity and global solar radiation were correlated with rainfall. Using the Self-Organizing Map algorithm, we show that heavy rainfall during an entire rainy season has a negative impact on social wasps. Strong contrasts in rainfall between the dry season and the short rainy season exacerbate this effect. Social wasp populations never recovered to their pre-2000 levels. This is probably because these conditions occurred over four years; heavy rainfall during the major rainy seasons during four other years also had a detrimental effect. On the contrary, low levels of rainfall during the major rainy season in 2009 spurred an increase in social wasp populations. We conclude that recent climatic changes have likely resulted in fewer social wasp colonies because they have lowered the wasps' resistance to parasitoids and pathogens. These results imply that Neotropical social wasps can be regarded as bio-indicators because they highlight the impact of climatic changes not yet perceptible in plants and other animals.
ISSN: 1932-6203

hal-00825825
https://hal.archives-ouvertes.fr/hal-00825825
https://hal.archives-ouvertes.fr/hal-00825825/document
https://hal.archives-ouvertes.fr/hal-00825825/file/Dejean2011_Climate.pdf
DOI : 10.1371/journal.pone.0027004

Éditeur(s) : HAL CCSD Human Kinetics
Résumé : International audience
The authors tested the effect of cold water ingestion during high-intensity training in the morning vs the evening on both core temperature (T C) and thermal perceptions of internationally ranked long-distance swimmers during a training period in a tropical climate. Nine internationally ranked long-distance swimmers (5 men and 4 women) performed 4 randomized training sessions (2 in the evening and 2 in the morning) with 2 randomized beverages with different temperatures for 3 consecutive days. After a standardized warm-up of 1000 m, the subjects performed a standardized training session that consisted of 10 × 100 m (start every 1′20″) at a fixed velocity. The swimmers were then followed for the next 3000 m of the training schedule. Heart rate (HR) was continuously monitored during the 10 × 100 m, whereas T C , thermal comfort, and thermal sensation (TS) were measured before and after each 1000-m session. Before and after each 1000 m, the swimmers were asked to drink 190 mL of neutral (26.5 ± 2.5°C) or cold (1.3 ± 0.3°C) water packaged in standardized bottles. Results demonstrated that cold water ingestion induced a significant effect on T C , with a pronounced decrease in the evening, resulting in significantly lower mean T C and lower mean delta T C in evening cold (EC) than in evening neutral (EN), concomitant with significantly lower TS in EC than in EN and a significant effect on exercise HR. Moreover, although T C increased significantly with time in MN, MC, and EN, T C was stabilized during exercise in EC. To conclude, we demonstrate that a cold beverage had a significant effect on T C , TS, and HR during training in high-level swimmers in a tropical climate, especially during evening training.
ISSN: 1555-0265

hal-01163459
https://hal.univ-antilles.fr/hal-01163459

Éditeur(s) : HAL CCSD University of Uludag
Résumé : International audience
We tested whether the silicone swim caps (SC) worn by young swimmers in a tropical climate negatively influence aerobic performance. Nine trained pre-adolescents [11.8 (± 0.8) years] swam randomized 800-m trials (water: 32.9°C, outdoors: shade, 29.2 ± 0.2 °C, 74 ± 0.3 % rh) with a SC or a nude head (NH). Performance times and heart rate (HR) were monitored continuously. Rectal temperature (T rec) was measured before and after trials. The rating of perceived exertion (RPE) was assessed. Stroke frequency (SF), stroke length (SL) and stroke index (SI) were measured every 50-m. The SC trial was significantly longer than NH (799 ± 16 and 781 ± 16 seconds, respectively). Mean delta T rec was significantly greater in SC (0.2 ± 0.1°C vs.-0.1 ± 0.1°C in SC vs. NH), mean SI was significantly different in SC versus NH (1.83 ± 0.07 vs 1.73 ± 0.06); but RPE and mean HR, SF and SL showed no change. We conclude that a silicone swim cap worn in tropical environment significantly decreased 800-m crawl performance without affecting HR or RPE. Silicone swim caps worn by young swimmers in a tropical environment may also have negative effects on training capacity.
ISSN: 1303-2968

hal-01137570
https://hal.univ-antilles.fr/hal-01137570
https://hal.univ-antilles.fr/hal-01137570/document
https://hal.univ-antilles.fr/hal-01137570/file/Hue%2C%20Galy%20-%202012%20-%20The%20effect%20of%20a%20silicone%20swim%20cap%20on%20swimming%20performance%20in%20tropical%20conditions%20in%20pre-adolescents.pdf

Éditeur(s) : HAL CCSD
Résumé : Food-grade dairy propionibacteria are nutraceutical producers. They release short chain fatty acids (SCFAs), folic acid and cobalamin, which play a role in intestinal physiology. SCFAs induce apoptosis via the mitochondrial death pathway. We investigated the potential of dairy propionibacteria-fermented products to synergize with drugs used in gastric and colorectal cancer.Fermented milk contained high and viable populations of propionibacteria. This product, as well as its cell-free supernatant, were tested in vitro on gastric HGT-1 and colic HT-29 cells with respect to apoptosis and synergy with known anti-cancer molecules, camptothecin and the human cytokine TRAIL (TNF Related Apoptosis Inducing Ligand). Viability was monitored and apoptosis quantified by Hoescht staining, ROS production, mitochondrial membrane potential perturbation and caspases activity assay. A transcriptomic study on genome-wide microarray was performed in collaboration with the company Miltenyi.Fermented milk induced cell death in both gastric and colon cancer cells. Characterization of cells revealed cell cycle arrest, drop in intracellular ATP, depolarization of mitochondria, translocation of key apoptosis proteins, processing of caspases and fragmentation of the nucleus. Interestingly, the fermented milk was shown to potentiate the cytotoxic effect of molecules used in cancer chemotherapy, camptothecin and TRAIL. The observed synergistic pro-apoptotic effect between TRAIL and propionibacterial SCFAs depended on death receptors and on caspases, was more lethal on cancer cells than on normal human intestinal epithelial cells (HIEC), and was inhibited by Bcl-2 expression. Transcriptomics revealed that propionibacterial metabolites boosted TRAIL-induced modulation of gene expression in human colon cancer cells.These results open new perspectives in the field of colon cancer cells prevention and/or treatment. The synergy with pro-apoptotic chemotherapy molecules suggests that such a fermented product, or the propionibacterium alone, may be proposed as a food supplement to enhance the effects of anticancer treatments.
The 2nd International conference on Cell Death In Cancer (CDIC)
La Baule, France

hal-01209622
https://hal.archives-ouvertes.fr/hal-01209622
PRODINRA : 261291

Éditeur(s) : HAL CCSD EDP Sciences
Résumé : International audience
This study determined the movements of a Giant Grouper, Epinephelus lanceolatus, in which an acoustictag was surgically implanted and monitored by an array of six VR2W acoustic receiver units from August 2010 toJanuary 2013 in the remote, uninhabited Chesterfield Islands, Coral Sea (800 km West of New Caledonia). Our datarevealed a home reef area (residency rate of 44.9%) with an increased activity revealed by movements at dawn anddusk toward and between two adjacent reef passages, probably for foraging. The fish was absent from its residentreef between October and December 2010 and 2012, corresponding to the time known for spawning aggregationsof this species in New Caledonia. A skipped spawning seems to have occurred in 2011. We hope these data will becomplemented in the future by locating the spawning site or sites and thus provide adequate conservation measures.The Coral Sea links two World Heritage Sites, the Australian Great Barrier Reefs and the New Caledonian coral reefs.It would be fitting to create a Marine Protected Area for the Chesterfield Islands between these two major conservationareas of the sea.
ISSN: 0990-7440

hal-01238809
https://hal-univ-perp.archives-ouvertes.fr/hal-01238809
DOI : 10.1051/alr/2015006

Éditeur(s) : HAL CCSD Springer Verlag
Résumé : International audience
Cnidarian-dinoflagellate symbiosis disruption and subsequent bleaching are major concerns, especially regarding their ecological consequences on coral reefs and temperate coralligenous communities. Cnidarian bleaching is caused by a variety of environmental stressors, such as elevated seawater temperature associated with global climate change, and by pollutants, such as herbicides and metals. Several cellular events have been described to explain symbiosis dysfunction and bleaching. Excess or damaged Symbiodinium symbionts are removed through a variety of mechanisms, including exocytosis, apoptosis, necrosis and autophagy. However, few studies have compared in the same species the relative involvement of these mechanisms, according to the stress inducing the bleaching. In this study, we used two different treatments —temperature and menthol— to induce bleaching in the sea anemone Anemonia viridis. By monitoring the ultrastructural tissue modifications, in control specimens we observed a basal rate of in situ symbiont digestion —or symbiophagy— induced by starvation. Symbiophagy was strongly induced in menthol-treated specimens and was the main cellular process of bleaching, whereas apoptosis and necrosis predominated in hyperthermal-induced bleaching. These results suggested a host effect through autophagy in menthol-treated specimens. These observations also suggested that symbiont removal may result from reengagement of the phagosomal maturation process in the host. These overall data demonstrate that several Symbiodinium cell removal mechanisms coexist and that stressors can activate one or more of these pathways, depending on the stress type, intensity or duration.
ISSN: 0334-5114

hal-01546908
http://hal.upmc.fr/hal-01546908
DOI : 10.1007/s13199-016-0406-y

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 Springer Verlag
Résumé : International audience
Heartwood/sapwood profile and the tradeoff between trunk and crown increment in a natural forest: the case study of a tropical tree (Dicorynia guianensis Amsh., Fabaceae) Key message Sapwood area and the radial growth rate of the trunk follow the same pattern at breast height, with an initial increase and subsequent constant value, resulting from the increasing growth allocation toward the crown rather than tree decline. Heartwood area and heartwood volume in the trunk increase more rapidly after this shift occurs. Abstract Sapwood (SW) and heartwood (HW) are two functionally distinct classifications of wood in perennial stems for which quantities can vary greatly in tropical trees. Numerous positive correlations have been found between the radial growth rate (RGR) and SW quantity; however, variations in the SW/HW quantities have not been studied in light of the ontogenetic variation of RGR. Wood core sampling, intensive measurements of tree structure (number of branches, stem volumes), and radial growth monitoring were performed on an abundant and highly exploited tree species in French Guiana (Dicorynia guianensis) to investigate the relationship between RGR, SW/HW quantity, tree structure, and their variations on the course of a tree's ontogeny. SW area and RGR followed the same pattern of variation throughout tree development, both increasing first and reaching a steady state after 50 cm DBH (diameter at breast height). After this value, we observed a strong increase in both the HW area and HW volume increment, concomitant with a more rapid increase in crown volume. The stabilization of RGR for trees with DBH >50 cm was related not to a tree's decline but rather to an increasing wood allocation to the crown, confirming that RGR at breast height is a poor indicator of whole-tree growth for bigger individuals. We also confirmed that HW formation is an ontogenetic process managing SW quantity that is continuously and increasingly produced within the crown as the tree grows. This study highlights the effect of growth-mediated ontogenetic changes on the localization of water and carbohydrate storage within a tree, resulting from SW and HW dynamics throughout tree ontogeny.
ISSN: 0931-1890

hal-01654003
https://hal.archives-ouvertes.fr/hal-01654003
https://hal.archives-ouvertes.fr/hal-01654003/document
https://hal.archives-ouvertes.fr/hal-01654003/file/Lehnebach%20et%20al.%E2%80%94Trees%202016-%20Own%20version.pdf
DOI : 10.1007/s00468-016-1473-7