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131.
Bernard Guyot Anne Bazin Yvette Sole Christophe Julien Fernand Daffos François Forestier 《黑龙江环境通报》1988,8(7):485-493
We have used a Y-chromosome specific DNA probe in a controlled study to determine the presence of Y-chromosome material and to detect numerical abnormalities in uncultured amniotic fluid cells by fluorescent hybridization. Using this non-radioactive method, we correctly predicted fetal sex within 48 h in all but 3 of 54 cases and identified an XYY syndrome. The technique was previously tested with no false-positive or false-negative results on cultured interphase or metaphase nuclei of fetal fibroblasts and adult T-lymphocytes. Fluorescent in situ hybridization was applied to long-term fixed cytogenetic preparations up to 44 months old and was shown to be reliable. 相似文献
132.
Magali?Combes David?Pinaud Christophe?Barbraud Jacques?Trotignon Fran?ois?BrischouxEmail author 《Die Naturwissenschaften》2018,105(1-2):5
Severe population declines of amphibians have been shown to be attributed to climate change. Nevertheless, the various mechanisms through which climate can influence population dynamics of amphibians remain to be assessed, notably to disentangle the relative synergetic or antagonistic influences of temperature and precipitations on specific life history stages. We investigated the impact of rainfall and temperature on the egg-clutch abundance in a population of agile frog (Rana dalmatina) during 29 years (1987–2016) on 14 breeding sites located in Brenne Natural Park, France. Specifically, we examined the influence of environmental conditions occurring during five temporal windows of the year cycle corresponding to specific life history stages. Overall, our results suggest that the year-to-year fluctuations of egg-clutch abundances in Brenne Natural Park were partly dependent on local climatic conditions (rainfall and temperature). Climate seemed to influence breeding frogs during the autumn-winter period preceding reproduction. Spring and summer conditions did not influence reproduction. Additionally, we failed to detect effects of climatic conditions on newly metamorphosed individuals. Other factors such as density dependence and inter-specific interactions with introduced predators are likely to play a significant role in reproduction dynamics of the studied frog populations. 相似文献
133.
Simon Ducatez Sébastien Dalloyau Pierre Richard Christophe Guinet Yves Cherel 《Marine Biology》2008,155(4):413-420
Individual specialisation is widespread and can affect a population’s ecological and evolutionary dynamics. Whether intra-specific
niche differences can influence reproductive investment was examined in a marine mammal, the southern elephant seal (Mirounga leonina), whose females were known to forage in two different areas during the austral winter. The study was conducted at Kerguelen
Islands (49°21′S, 70°18′E), southern Indian Ocean, in late winter–early spring 2006. Pups were used as proxies of their mothers’
biology and combined information on their weaning mass (a proxy of females’ foraging success and short-term fitness) together
with their blood δ13C value (a proxy of female foraging zone). First, the use of isotopic signature of pups was validated to study the female
foraging ecology during their pre-breeding trip by demonstrating that δ13C and δ15N values of pups and their mothers were positively and linearly correlated. Then, blood samples were taken from a large number
of newly-weaned pups, which were also weighed, to provide information at the population level. Estimated δ13C values of female seals encompassed a large range of values (from −23.7 to −19.1‰) with an unimodal frequency distribution,
suggesting no contrasted foraging areas within the population. No significant relationship was found between pup weaning mass
and their carbon signature, indicating no link between female foraging areas and maternal foraging success and investment.
Finally, blood δ13C and δ15N values gave new insights into southern elephant seal ecology, suggesting that females mainly foraged north of the Polar
Front where they preyed upon myctophid fish in late winter. 相似文献
134.
Specialized bees fail to develop on non-host pollen: do plants chemically protect their pollen? 总被引:1,自引:0,他引:1
Bees require large amounts of pollen for their own reproduction. While several morphological flower traits are known to have evolved to protect plants against excessive pollen harvesting by bees, little is known on how selection to minimize pollen loss acts on the chemical composition of pollen. In this study, we traced the larval development of four solitary bee species, each specialized on a different pollen source, when reared on non-host pollen by transferring unhatched eggs of one species onto the pollen provisions of another species. Pollen diets of Asteraceae and Ranunculus (Ranunculaceae) proved to be inadequate for all bee species tested except those specialized on these plants. Further, pollen of Sinapis (Brassicaceae) and Echium (Boraginaceae) failed to support larval development in one bee species specialized on Campanula (Campanulaceae). Our results strongly suggest that pollen of these four taxonomic groups possess protective properties that hamper digestion and thus challenge the general view of pollen as an easy-to-use protein source for flower visitors. 相似文献
135.
Susan E. Ford V. Monica Bricelj Christophe Lambert Christine Paillard 《Marine Biology》2008,154(2):241-253
The known negative effects of shellfish toxin-producing dinoflagellates on feeding, burrowing and survival of some bivalve
mollusks has prompted questions concerning whether they might also impair the internal defense system of affected bivalves
and make them more susceptible to disease agents. The primary components of the cellular defense system are hemocytes. Many
toxic dinoflagellates are too large to be ingested whole by hemocytes and would most likely be exposed to intracellular toxins
only after the algae are consumed, broken down, and the water-soluble toxins, released. Therefore, we conducted a series of
experiments in which hemocytes from two suspension-feeding bivalves—the Manila clam, Ruditapes philippinarum, and the softshell clam, Mya arenaria—were exposed in vitro to filtered extracts of one highly toxic paralytic shellfish toxin (PST)-producing and one nonPST-producing
strain of Alexandrium tamarense (isolates PR18b, 76 ± 6 STXeq cell−1 and CCMP115, with undetectable PST, respectively). We measured adherence and phagocytosis, two hemocyte attributes known
to be inhibited by bacterial pathogens and other stressors. We found no measurable effect of a cell-free extract from a highly
concentrated suspension of the PST-producing strain on hemocytes of either bivalve species. Instead, extract from the nonPST-producing
strain had a consistent negative effect on both clams, resulting in significantly lower adherence and phagocytosis compared
to strain PR18b and filtered seawater controls. The bioactive compound produced by strain CCMP115, which has yet to be characterized,
may be similar to the PST-independent allelopathic compounds described for Alexandrium spp., which act on other plankters. These compounds and those produced by other harmful algae are known to cause immobilization,
cellular deformation and lysis of co-occurring target organisms. Thus, nonPST producing Alexandrium spp., which do not cause paralysis and burrowing incapacitation of clams, may still produce a compound(s) that has negative
effects not only on hemocytes, but on other molluscan cell types and their functions, as well. 相似文献
136.
Manipulating decay time for efficient large-mammal density estimation: gorillas and dung height 总被引:2,自引:0,他引:2
Hjalmar S Kuehl Angelique Todd Christophe Boesch Peter D Walsh 《Ecological applications》2007,17(8):2403-2414
Large-mammal surveys often rely on indirect signs such as dung or nests. Sign density is usually translated into animal density using sign production and decay rates. In principle, such auxiliary variable estimates should be made in a spatially unbiased manner. However, traditional decay rate estimation methods entail following many signs from production to disappearance, which, in large study areas, requires extensive travel effort. Consequently, decay rate estimates have tended to be made instead at some convenient but unrepresentative location. In this study we evaluated how much bias might be induced by extrapolating decay rates from unrepresentative locations, how much effort would be required to implement current methods in a spatially unbiased manner, and what alternate approaches might be used to improve precision. To evaluate the extent of bias induced by unrepresentative sampling, we collected data on gorilla dung at several central African sites. Variation in gorilla dung decay rate was enormous, varying by up to an order of magnitude within and between survey zones. We then estimated what the effort-precision relationship would be for a previously suggested "retrospective" decay rate (RDR) method, if it were implemented in a spatially unbiased manner. We also evaluated precision for a marked sign count (MSC) approach that does not use a decay rate. Because they require repeat visits to remote locations, both RDR and MSC require enormous effort levels in order to gain precise density estimates. Finally, we examined an objective criterion for decay (i.e., dung height). This showed great potential for improving RDR efficiency because choosing a high threshold height for decay reduces decay time and, consequently, the number of visits that need to be made to remote areas. The ability to adjust decay time using an objective decay criterion also opens up the potential for a "prospective" decay rate (PDR) approach. Further research is necessary to evaluate whether the temporal bias inherent in such an approach is small enough to ignore, given the 10-20-fold increases in precision promised by a PDR approach. 相似文献
137.
Among social animals, group size is constrained by competition over resources. Because female reproductive success is limited by access to food resources, and that of males by access to fertile females, chimpanzee females are proposed to be less social than males and to maintain weak intrasexual relations. Findings from Taï National Park, Côte d’Ivoire, challenged this view, as chimpanzee females were described as generally gregarious, and close intrasexual bonds were common. Here, in a new analysis that focuses on the South Group of chimpanzees in Taï forest, we reevaluate the proposed differences in female association patterns between the Taï and East African populations. We find that mean party size and dyadic association index between females has decreased in Taï, although the level of dyadic associations remains high compared with East African chimpanzees. We attribute the decrease in female gregariousness to the decline in community size over the last 10 years. In addition, we use a multivariate approach to analyze social and ecological factors influencing party size in females. We show that female gregariousness increased when the fruit resources were more clumped and with increased number of females in estrus present. Party size of mothers with sons, however, was smaller with increasing number of sexually receptive females. The results of our model and the reviewed findings of other studies support the socioecological model because food distribution affects female gregariousness, but social and demographic aspects are equally influencing female grouping tendencies. 相似文献
138.
Mette M. Broholm Catherine Crouzet Erik Arvin Christophe Mouvet 《Journal of contaminant hydrology》2000,44(3-4)
The biodegradation of phenols (5, 60, 600 mg l−1) under anaerobic conditions (nitrate enriched and unamended) was studied in laboratory microcosms with sandstone material and groundwater from within an anaerobic ammonium plume in an aquifer. The aqueous phase was sampled and analyzed for phenols and selected redox sensitive parameters on a regular basis. An experiment with sandstone material from specific depth intervals from a vertical profile across the ammonium plume was also conducted. The miniature microcosms used in this experiment were sacrificed for sampling for phenols and selected redox sensitive parameters at the end of the experiment. The sandstone material was characterized with respect to oxidation and reduction potential and Fe(II) and Fe(III) speciation prior to use for all microcosms and at the end of the experiments for selected microcosms.The redox conditions in the anaerobic microcosms were mixed nitrate and Fe(III) reducing. Nitrate and Fe(III) were apparently the dominant electron acceptors at high and low nitrate concentrations, respectively. When biomass growth is taken into account, nitrate and Fe(III) reduction constituted sufficient electron acceptor capacity for the mineralization of the phenols observed to be degraded even at an initial phenols concentration of 60 mg l−1 (high) in an unamended microcosm, whereas nitrate reduction alone is unlikely to have provided sufficient electron acceptor capacity for the observed degradation of the phenols in the unamended microcosm.For microcosm systems, with solid aquifer materials, dissolution of organic substances from the solid material may occur. A quantitative determination of the speciation (mineral types and quantity) of electron acceptors associated with the solids, at levels relevant for degradation of specific organic compounds in aquifers, cannot always be obtained. Hence, complete mass balances of electron acceptor consumption for specific organic compounds degradation are difficult to confine. For aquifer materials with low initial Fe(II) content, Fe(II) determinations on solids and in aqueous phase samples may provide valuable information on Fe(III) reduction. However, in microcosms with natural sediments and where electron acceptors are associated with the sediments, complete mass-balances for substrates and electron acceptors are not likely to be obtained. 相似文献
139.
Visualization by light transmission of oil and water contents in transient two-phase flow fields 总被引:1,自引:0,他引:1
Christophe J. G. Darnault James A. Throop David A. DiCarlo Alon Rimmer Tammo S. Steenhuis J. -Yves Parlange 《Journal of contaminant hydrology》1998,31(3-4)
The difficulty of determining transient fluid contents in a soil–oil–water system is hampering an understanding of the system's flow characteristics. In this paper, we describe a light transmission method (LTM) which can rapidly obtain oil and water contents throughout a large two-dimensional flow field of silica sand. By appropriately coloring the water with 0.005% FD&C blue #1, the hue of the transmitted light is found to be directly related to the water content within the porous media. The hue provides a high resolution measurement of the water and oil contents in transient flow fields (such as unstable flow). Evaluation of the reliability of LTM was assessed by checking the mass balance for a known water injection and its utility in visualizing a whole flow field was exemplified for unstable fingered flow by comparing fluid contents to those obtained with synchrotron X-ray radiation. 相似文献
140.
Xavier Laffray Christophe Rose Jean-Pierre Garrec 《Environmental pollution (Barking, Essex : 1987)》2010,158(5):1652-1660
Effects of traffic-related nitrogenous emissions on purple moor grass (Molinia caerulea (L.) Moench) transplants, used here as a new biomonitoring species, were assessed along 500 m long transects orthogonal to roads located in two open areas in the Maurienne valley (French Alps). Leaves were sampled during summer 2004 and 2005 for total N-content and 15N-abundance determination while nitrogen oxides (NO and NO2) concentrations were determined using passive diffusion samplers. A significant and negative correlation was observed between plant total N-content, and 15N-abundance and the logarithm of the distance to the road axis. The strongest decreases in plant N parameters were observed between 15 and 100 m from road axis. They were equivalent to background levels at a distance of about 800 m from the roads. In addition, motor vehicle pollution significantly affected vegetation at road edge, as was established from the relationship between leaf 15N-abundance, total N-content and road traffic densities. 相似文献