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Southwest France (southwest + france)

Distribution by Scientific Domains

Life Sciences	33%

Selected Abstracts

Ontogenetic Microhabitat Shifts in the Bullhead, Cottus gobio L.,in a Fast Flowing Stream

INTERNATIONAL REVIEW OF HYDROBIOLOGY, Issue 3 2005
Milène Legalle
Abstract We investigated differences in microhabitat preference curves for bullheads, Cottus gobio L., of different size-classes during low flow periods, and evaluated the influence of such differences on habitat use through Weighted Usable Area (WUA) predictions in relation to river flow in a piedmont stream in Southwest France. Water depth, current velocity, and substratum composition were used to calculate proportional use values for each size-class (SC), and to quantify size-specific microhabitat preferences. Bullhead used non-cohesive and coarse mineral particles (pebbles, cobbles, boulders), but there was a spatial segregation of individuals from different size classes (SC1,SC4). Smaller bullhead (SC1, total length <60 mm) took refuge under cobbles, significantly preferred shallower areas, and were less prone to select high current velocities than larger bullhead (SC 2 to 4, >60 mm), the latter occurring below (or under) the largest particles, where current velocity is weakened and sand accumulates. SC1 bullhead had a more restricted range for each habitat descriptors, and were thus likely to require a more specific habitat type than other bullhead. The maximum WUA values and the related preferred discharges (0.15,0.75 m3 s,1) depended on the considered size-class. Our results suggest that ontogenetic niche shifts may play a role in the structure and dynamics of populations, by adjusting species' requirements to the spatial and temporal dynamics of environmental conditions, including abiotic and biotic conditions. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Variation of reproductive behaviour and success of males adopting different tactics in Atlantic salmon

JOURNAL OF FISH BIOLOGY, Issue 2003
B. De Gaudemar
Six males and five females anadromous Atlantic salmon were released in two sections of the Lapitxuri experimental stream (Southwest France), where they could reproduce naturally. Females had all the same size and age, contrary to males. We focussed our attention on the variation with time of spawning tactics and success of males. Two factors affected male spawning behaviour in the short term. An increase of the OSR increased the level of male competition around redds which resulted in a larger number of males adopting sneaking rather than fighting tactics. Changes in female activities also seemed to be detected by males, since male aggressiveness increased when females were close to oviposition. But whatever their activities, males preferentially courted the earlier spawning female when two females were active at the same time. Fighting in males was confirmed to be the most successful tactic at a given time. However, males adopting sneaking tactic at the beginning of the spawning season could dramatically increase their reproductive success in the long-term. Fighting males invested much more energy in contests than secondary males, which may constitute a handicap in terms of longevity. They could quickly lose their status or strength with time which, although placed in a situation of high OSR, resulted in greater numbers of previously low-ranking males adopting satellite and fighting tactics during the period preceding oviposition. Age more than size affected male status and reproductive success. Females seemed to select their mate directly in relation to their physiological condition, since they only attacked dull coloured males showing obvious wound marks. They also could indirectly choose their mate by repeatedly leaving the redd during the period preceding oviposition in a situation of high OSR. This behaviour might incite male competition and also promoted, by incessant attempts of secondary males to rob the more successful status of primary males, their chance to spawn with fitter males. These results emphasized the importance of environment, physiological condition and energy expenditure in allocation tactics and variations in salmon reproductive success throughout the spawning season. This led us to hypothesize that the choice of sneaking through conditional strategies might provide greater average fitness in salmon alternative life histories. [source]

Case ascertainment and estimated incidence of drug-induced long-QT syndrome: study in Southwest France

BRITISH JOURNAL OF CLINICAL PHARMACOLOGY, Issue 3 2008
Mariam Molokhia
WHAT IS ALREADY KNOWN ABOUT THIS SUBJECT , Drug-induced long-QT syndrome (LQTS) is a potentially fatal condition that has led to a number of postmarketing withdrawals in recent years. , However, many cases may not survive long enough to reach hospital, and only a small proportion are reported to pharmacovigilance agencies. , The extent to which genetic determinants of susceptibility to LQTS are specific to particular drugs, or common to several classes of drug, remains to be determined. WHAT THIS STUDY ADDS , We estimated population prevalence of drug-induced LQTS in the Midi-Pyrenees region, southwest France, using five different institutions and assessed feasibility of tracing potential cases (in addition to pharmacovigilance data), using hospital data and rigorous case definition. , These methods can be adapted to a wider region, used to augment pharmacovigilance reporting, and offer researchers the opportunity to study genetic susceptibility to drug-induced LQTS. AIMS The aim of this study was to investigate the incidence and reporting rate of drug-induced long-QT syndrome (LQTS) in France [defined by evidence of torsades de pointes (TdP), QT prolongation and exposure to a relevant drug] and to assess feasibility of case collection for drug-induced LQTS. METHODS A retrospective population-based study was carried out in Southwest France in five institutions: three main hospitals, one private clinic and one cardiac emergency unit, searched from 1 January 1999 to 1 January 2005 (population coverage of 614 000). The study population consisted of 861 cases with International Classification of Diseases-10 diagnostic codes for ventricular tachycardia (I147.2), ventricular fibrillation (I149.0) and sudden cardiac death (I146.1) from hospital discharge summaries, supplemented by cases reported to national or regional pharmacovigilance systems, and voluntary reporting by physicians, validated according to internationally defined criteria for drug-induced LQTS. RESULTS Of 861 patients coded with arrhythmias or sudden cardiac death, there were 40 confirmed surviving acquired cases of drug-induced LQTS. We estimated that the incidence of those who survive to reach hospital drug-induced LQTS is approximately 10.9 per million annually in France (95% confidence interval 7.8, 14.8). CONCLUSIONS Many cases of drug-induced LQTS may not survive before they reach hospital, as the reporting rate for drug-induced LQTS identified through the cardiology records and also reported to pharmacovigilance systems for the Midi-Pyrenees area is 3/40 (7.5%). Using the methods outlined it is possible to assemble cases to study genetic susceptibility to drug-induced LQTS and adapt these methods more widely. [source]

Dispersal characteristics of three odonate species in a patchy habitat

ECOGRAPHY, Issue 1 2003
S. Angelibert
Dispersal has a potentially profound effect on the dynamics of populations especially when a population occupies a patchy habitat. Ponds surrounded by terrestrial landscape are an example of patchy distribution of physical conditions and constitute "islands" for odonates. Few studies have focussed on dispersal in odonates. We have used the direct method of dispersal observing (capture-mark-recapture technique) in order to estimate the degree of linkage in three patchy populations of odonate localised on three ponds. We also examined the differences in dispersal ability within and among three species (Coenagrion puella, Coenagrion scitulum and Libellula depressa). The ponds were situated in southwest France on a limestone plateau. In this arid area, these ponds constitute the only surface water available and are relatively sparsely distributed. The size of the ponds ranged from 48 to 79 m2 and they were 200 and 775 m apart. We demonstrated that three factors influence the dispersal ability of these odonates. The first is represented by the abiotic factors and especially weather conditions. This determines the number of days that dispersal is possible. The second is interspecific differences. We showed that sensitivity to weather conditions, species size and species behaviour influence dispersal ability. The third factor is the intraspecific characteristics. We demonstrated that there are differences in dispersal ability according to sex and age. To conclude, we discuss the importance of pond management to maintain the existing odonate populations and to facilitate introduction of new populations in this region where little exchange occurs between ponds. [source]