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Southeastern France (southeastern + france)
Selected AbstractsAnalyses of the stress field in southeastern France from earthquake focal mechanismsGEOPHYSICAL JOURNAL INTERNATIONAL, Issue 2 2001Emmanuel Baroux Summary Owing to the apparent deformation field heterogeneity, the stress regimes around the Provence block, from the fronts of the Massif Central and Alpine range up to the Ligurian Sea, have not been well defined. To improve the understanding of the SE France stress field, we determine new earthquake focal mechanisms and compute the present-day stress states by inversion of the 89 available focal mechanisms around the Provence domain, including 17 new ones calculated in the current study. This study provides evidence of six distinct deformation domains around the Provence block, with different tectonic regimes. On a regional scale, we identify three zones characterized by significantly different stress regimes: a western one affected by an extensional stress (normal faulting) regime; a southeastern one characterized by a compressional stress (reverse to strike-slip faulting) regime with NNW- to WNW-trending ,1; and a northeastern one, namely the Digne nappe front, marked by a NE-trending compression. Note that the Digne nappe back domain is controlled by an extensional regime that is deforming the western Alpine core. This extensional regime could be a response to buoyancy forces related to the Alpine high topography. The stress regimes in the southeast of the Argentera Massif and around the Durance fault are consistent with a coherent NNW-trending ,1, implying a left-lateral component of the active reverse oblique slip of the Moyenne Durance Fault. In the Rhone Valley, an E-trending extension characterizes the tectonic regime, implying a normal component of the present-day N,^mes fault displacement. This study provides evidence for short-scale variation of the stress states, which arises from abrupt changes in the boundary force influences on upper crustal fragments (blocks). These spatial stress changes around the Provence block result from the coeval influence of forces applied at both its extremities, namely in the northeast the Alpine front push, and in the southeast the northward African plate drift. In addition to these boundary forces, the mantle plume under the Massif Central influences the western block boundary. [source] Polymorphism and drug-selected mutations in the reverse transcriptase gene of HIV-2 from patients living in southeastern FranceJOURNAL OF MEDICAL VIROLOGY, Issue 3 2005Philippe Colson Abstract Few data are available about the susceptibility and the genotypic resistance pattern of human immunodeficiency virus type 2 (HIV-2) to nucleoside reverse transcriptase inhibitors (NRTIs). The HIV-2 reverse transcriptase (RT) gene from 25 HIV-2-infected patients followed-up in Marseilles and the surrounding area was analyzed. The aims of this study were to characterize the polymorphism of HIV-2 RT in the absence of drug, to determine whether it naturally harbors codons associated with drug-resistance in HIV-1, and to identify mutations emerging under NRTI-selective pressure. Fourteen patients had never undergone antiretroviral therapy and 11 received NRTI. Seventy sequences were analyzed. In untreated patients, 12 spots of high natural polymorphism (at positions 10, 11, 20, 43, 104, 121, 135, 162, 176, 180, 200, and 227) were observed; 4 of them were specific of HIV-2 (10, 176, 180, 227). Moreover, results showed four positions that could be associated with natural resistance to NRTI (75I, 118I, 219E, and perhaps 215S), in addition to those described previously for non-nucleoside reverse transcriptase inhibitors (NNRTIs) (181I, 188L, 190A). In HIV-2-infected patients receiving NRTI-containing therapies, specific genotypic patterns were observed with a high frequency of mutation Q151M (in 45% of patients) often associated with 70R, 115F, 214L, and/or 223R, which might compose an HIV-2 multi-NRTI resistance complex. Four newly or rarely described NRTI-selected mutations were observed: I5V, K35R, F214L, and K223R. As in HIV-1, substitution M184V was found in 3TC-treated patients. In conclusion, these findings highlight the need for specific guidelines for determining genotypic resistance and treatment of HIV-2. J. Med. Virol. 75:381,390, 2005. © 2005 Wiley-Liss, Inc. [source] Were last glacial climate events simultaneous between Greenland and France?JOURNAL OF QUATERNARY SCIENCE, Issue 3 2010A quantitative comparison using non-tuned chronologies Several large abrupt climate fluctuations during the last glacial have been recorded in Greenland ice cores and archives from other regions. Often these Dansgaard,Oeschger events are assumed to have been synchronous over wide areas, and then used as tie-points to link chronologies between the proxy archives. However, it has not yet been tested independently whether or not these events were indeed synchronous over large areas. Here, we compare Dansgaard,Oeschger-type events in a well-dated record from southeastern France with those in Greenland ice cores. Instead of assuming simultaneous climate events between both archives, we keep their age models independent. Even these well-dated archives possess large chronological uncertainties that prevent us from inferring synchronous climate events at decadal to multi-centennial time scales. If possible, comparisons between proxy archives should be based on independent, non-tuned time-scales. Copyright © 2009 John Wiley & Sons, Ltd. [source] Parallel changes in genetic diversity and species diversity following a natural disturbanceMOLECULAR ECOLOGY, Issue 6 2009GUILLAUME EVANNO Abstract We examined the spatial and temporal variation of species diversity and genetic diversity in a metacommunity comprising 16 species of freshwater gastropods. We monitored species abundance at five localities of the Ain river floodplain in southeastern France, over a period of four years. Using 190 AFLP loci, we monitored the genetic diversity of Radix balthica, one of the most abundant gastropod species of the metacommunity, twice during that period. An exceptionally intense drought occurred during the last two years and differentially affected the study sites. This allowed us to test the effect of natural disturbances on changes in both genetic and species diversity. Overall, local (alpha) diversity declined as reflected by lower values of gene diversity HS and evenness. In parallel, the among-sites (beta) diversity increased at both the genetic (FST) and species (FSTC) levels. These results suggest that disturbances can lead to similar changes in genetic and community structure through the combined effects of selective and neutral processes. [source] Range-wide phylogeography and gene zones in Pinus pinaster Ait. revealed by chloroplast microsatellite markersMOLECULAR ECOLOGY, Issue 10 2007GABRIELE BUCCI Abstract Some 1339 trees from 48 Pinus pinaster stands were characterized by five chloroplast microsatellites, detecting a total of 103 distinct haplotypes. Frequencies for the 16 most abundant haplotypes (pk > 0.01) were spatially interpolated over a lattice made by 430 grid points. Fitting of spatially interpolated values on raw haplotype frequencies at the same geographical location was tested by regression analysis. A range-wide ,diversity map' based on interpolated haplotype frequencies allowed the identification of one ,hotspot' of diversity in central and southeastern Spain, and two areas of low haplotypic diversity located in the western Iberian peninsula and Morocco. Principal component analysis (PCA) carried out on haplotypes frequency surfaces allowed the construction of a colour-based ,synthetic' map of the first three PC components, enabling the detection of the main range-scale genetic trends and the identification of three main ,gene pools' for the species: (i) a ,southeastern' gene pool, including southeastern France, Italy, Corsica, Sardinia, Pantelleria and northern Africa; (ii) an ,Atlantic' gene pool, including all the western areas of the Iberian peninsula; and (iii) a ,central' gene pool, located in southeastern Spain. Multivariate and amova analyses carried out on interpolated grid point frequency values revealed the existence of eight major clusters (,gene zones'), whose genetic relationships were related with the history of the species. In addition, demographic models showed more ancient expansions in the eastern and southern ranges of maritime pine probably associated to early postglacial recolonization. The delineation of the gene zones provides a baseline for designing conservation areas in this key Mediterranean pine. [source] Isolation by distance and sharp discontinuities in gene frequencies: implications for the phylogeography of an alpine insect species, Carabus solieriMOLECULAR ECOLOGY, Issue 7 2004S. GARNIER Abstract Analysis of genetic isolation by distance (IBD) is of prime importance for the study of processes responsible for spatial population genetic structure and is thus frequently used in case studies. However, the identification of a significant IBD pattern does not necessarily imply the absence of sharp discontinuities in gene frequencies. Therefore, identifying barriers to gene flow and/or secondary contact between differentiated entities remains a major challenge in population biology. Geographical genetic structure of 41 populations (1080 individuals) of an alpine insect species, Carabus solieri, was studied using 10 microsatellite loci. All populations were significantly differentiated and spatially structured according to IBD over the entire range. However, clustering analyses clearly identified three main clusters of populations, which correspond to geographical entities. Whereas IBD also occurs within each cluster, population structure was different according to which group of populations was considered. The southernmost cluster corresponds to the most fragmented part of the range. Consistently, it was characterized by relatively high levels of differentiation associated with low genetic diversity, and the slope of the regression of genetic differentiation against geographical distances was threefold those of the two other clusters. Comparisons of within-cluster and between-cluster IBD patterns revealed barriers to gene flow. A comparison of the two approaches, IBD and clustering analyses, provided us with valuable information with which to infer the phylogeography of the species, and in particular to propose postglacial colonization routes from two potential refugia located in Italy and in southeastern France. Our study highlights strongly the possible confounding contribution of barriers to gene flow to IBD pattern and emphasizes the utility of the model-based clustering analysis to identify such barriers. [source] Restoration of a Mediterranean Postfire Shrubland: Plant Functional Responses to Organic Soil AmendmentRESTORATION ECOLOGY, Issue 5 2010Marie Larchevêque We investigated the potential of plant functional responses to speed up restoration in a postfire ecosystem. The patterns of change in plant nutrient uptake and water potential after compost amendment were monitored for 2 years in a 7-year-old postfire shrubland in southeastern France. We studied four different stress-tolerant species with contrasting life traits: three shrub species and a perennial herb. Three treatments were applied: control, 50 and 100 Mg/ha of fresh cocomposted sewage sludge and green waste. In both compost treatments, concentrations of all the macronutrients increased. The amendment improved N and cation nutrition, but the positive effect of compost on plant nutrient status was most apparent on leaf P concentrations, indicating that P was a limiting nutrient in this shrubland. Compost had no significant short-term effect on trace metal concentrations in plants. The plant nutrition response of different species to the compost varied; the nutritional status of Brachypodium retusum and Cistus albidus improved the most, whereas that of Quercus coccifera and Ulex parviflorus improved the least. Woody species exhibited no increase in N stocks. Phosphorus accumulation was also about three times higher in plots amended at 50 Mg/ha than in control plots for B. retusum and C. albidus. The severe summer drought of 2003 altered the compost effect. Contrary to our expectations, plants on amended plots did not exhibit a better water status in summer: the effect of the summer drought had a greater effect on water status than did the compost treatment. [source] | ||||||||||