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991.
Summary A comparative analysis of the relatively rich shelled gastropod and bivalve fauna of two transects from 200 to 2,000 m in the eastern Weddell Sea was done by trawls and multibox corer. Related to the unusual shelf topography, a characteristic pattern of abundance and species richness with depth and location is evidenced. Highest values of species richness are observed near the ice-shelf edge and from the rise of the shelf to some 800 m on the slope, and lowest values between 300 and 600 m on the inner slope. This anomalous pattern, not followed by the biomass, is interpreted as a consequence of both historical factors (problems of colonization of the shelf) and present food supply. Most of the species are eurybathic and eurytopic. Generally speaking, assemblages are patchy but tend to be arranged by depth zones.Data presented here were collected during the European Polarstern Study (EPOS) sponsored by the European Science Foundation 相似文献
992.
J. Galéron R. L. Herman P. M. Arnaud W. E. Arntz S. Hain M. Klages 《Polar Biology》1992,12(2):283-290
Summary During the third leg of the European Polarstern Study (EPOS leg 3) in the austral summer season 1989, benthic macrofaunal communities were sampled from the Elephant Island area (61° southern latitude) and from Kapp Norvegia (71° southern latitude) to Halley Bay (75°30 southern latitude) using a commercial bottom trawl and an Agassiz trawl. Thirty-six trawl samples from a depth range of about 200–2,000 m were considered, with most of the samples being from the shelf and upper slope. Multivariate analysis techniques (clustering and TWIN-SPAN) discriminated between an eastern and a southern community in which parallel subgroups can be distinguished at increasing distance from the ice shelf.Data presented here were collected during the European Polarstern Study (EPOS) sponsored by the European Science Foundation 相似文献
993.
Renal function was studied in 15 newborn New Zealand rabbits administered either 0.6 mg/kg enprofylline intravenously. Each animal acted as its own control. Glomerular filtration rate (GFR) and renal blood flow (RBF) were assessed by the clearances of inulin and para-aminohippuric acid, respectively. Enprofylline, a xanthine with low adenosine antagonistic properties, did not modify urine flow rate, GFR, RBF, renal vascular resistance, filtration fraction, sodium and potassium urinary excretion, whereas administration of theophylline, a potent adenosine antagonist, was associated with a significant increase in diuresis, renal vascular resistance and filtration fraction. The differences observed in the renal effects of theophylline and enprofylline strongly support the view that 1) the renal actions of micromolar concentrations of theophylline are mediated by an antagonism with endogenous renal adenosine; 2) renal adenosine could play a physiological role in the regulation of renal hemodynamics. 相似文献
994.
995.
The historical file of Moulin Quignon (Abbeville, France), around the human jaw unearthed in this site, is a form of black hole that swallowed a prehistoric archaeological site and Lower Palaeolithic collection. This article, based on a corpus of unpublished archives, illuminates the matter in a different light. It focuses on archaeological and epistemological issues, the roles of the different actors, interaction games and solidarity in a global scientific community previously welded by the recognition in 1859 of the paradigm of high antiquity of Man. 相似文献
996.
997.
Guillaume J. M. Laugier Gilles Le Moguédec Wang Su Ashraf Tayeh Laurent Soldati Bruno Serrate Arnaud Estoup Benoît Facon 《Biological invasions》2016,18(10):2871-2881
Understanding biological invasion is currently one of the main scientific challenges for ecologists. The introduction process is crucial for the success of an invasion, especially when it involves a demographic bottleneck. A small introduced population is expected to face a higher risk of extinction before the first stage of invasion is complete if inbreeding depression, caused by the expression of deleterious alleles, is important. Changes in mating regimes or in population size can induce the evolution of deleterious allele frequencies, either by selection or by drift, possibly resulting in the purging or the fixation of such alleles within the population. The harlequin ladybird Harmonia axyridis became invasive on several continents following a scenario including at least one event of demographic bottleneck. Although native populations suffered from severe inbreeding depression, it was greatly reduced in invasive ones suggesting that deleterious alleles were purged during the invasion process. In this study, we performed an experiment designed to manipulate the effective population size of H. axyridis across successive generations to mimic contrasting introduction events. We used the measurement of two fitness-related phenotypic traits in order to test (1) if inbreeding depression can evolve at the time-scale of an invasion; and (2) if the changes in inbreeding depression following a bottleneck in laboratory conditions are compatible with the purging of deleterious alleles observed in this species. We found that two generations of very low population size are enough to induce a substantial change in inbreeding depression. Although the genetic changes mostly consisted in fixation of deleterious alleles, purging did also occur, sometimes simultaneously with fixation. 相似文献
998.
Arnaud Billet Yanlin Jia Timothy J. Jensen Yue-Xian Hou Xiu-Bao Chang John R. Riordan 《Channels (Austin, Tex.)》2016,10(3):247-251
The CFTR chloride channel is tightly regulated by phosphorylation at multiple serine residues. Recently it has been proposed that its activity is also regulated by tyrosine kinases, however the tyrosine phosphorylation sites remain to be identified. In this study we examined 2 candidate tyrosine residues near the boundary between the first nucleotide binding domain and the R domain, a region which is important for channel function but devoid of PKA consensus sequences. Mutating tyrosines at positions 625 and 627 dramatically reduced responses to Src or Pyk2 without altering the activation by PKA, suggesting they may contribute to CFTR regulation. 相似文献
999.
1000.
Else J Fjerdingstad Nicolas Schtickzelle Pauline Manhes Arnaud Gutierrez Jean Clobert 《BMC evolutionary biology》2007,7(1):133