Are Amphipod invaders a threat to the regional biodiversity? Conservation prospects for the Loire River

The impact of invasions on local biodiversity is well established, but their impact on regional biodiversity has so far been only sketchily documented. To address this question, we studied the impact at various observation scales (ranging from the microhabitat to the whole catchment) of successive arrivals of non-native amphipods on the amphipod assemblage of the Loire River basin in France. Amphipod assemblages were studied at 225 sites covering the whole Loire catchment. Non-native species were dominant at all sites in the main channel of the Loire River, but native species were still present at most of the sites. We found that the invaders have failed to colonize most of tributaries of the Loire River. At the regional scale, we found that since the invaders first arrived 25 years ago, the global amphipod diversity has increased by 33% (from 8 to 12 species) due to the arrival of non-native species. We discuss the possibility that the lack of any loss of biodiversity may be directly linked to the presence of refuges at the microhabitat scale in the Loire channel and in the tributaries, which invasive species have been unable to colonize. The restoration of river quality could increase the number of refuges for native species, thus reducing the impact of invader

Rôle de la transferrine dans la fonction testiculaire et son contrôle par les gonadotropines

*INRA Bibliothèque PRC -37380 Nouzilly (FRA) Diffusion du document : INRA Bibliothèque PRC -37380 Nouzilly (FRA) Diplôme : Dr. d'Universit

The costs and benefits of maternal egg care in the earwig Forficula pubescens

International audienceMaternal egg care is generally considered to be ubiquitous among the 1,700 species of freeliving Dermaptera. However, the forms, costs, and benefits of egg care have only been studied in a handful of species. In this study, we examined for the first time egg care in the earwig Forficula pubescens. Under standard laboratory conditions, we set up 94 families containing mothers with either no eggs, a reduced, normal or increased clutch size, or eggs without mother. We first demonstrate that F. pubescens mothers indeed express multiple forms of egg care including egg grooming, egg guarding, and active defences against predators, some of which vary with clutch size. However, maternal presence had contrasting effects on the eggs' fate. On one hand, it reduced the survival of eggs during their first 30 days of development, which suggests that mothers eat part of their clutch during egg development and, contrary to other Dermapterans, that abandoned eggs can resist fungal development. On the other hand, maternal presence was necessary to allow the remaining eggs to hatch on day 53, indicating that mothers enhance late embryonic development and/or facilitate the hatching process. Finally, our results did not shed light on the costs of egg care for mothers in terms of premature death, reduced expression of self-grooming, or increased weight loss. Overall, our study emphasizes that investigating the costs and benefits of egg care in poorly known species can provide novel insights into our understanding of the evolution of maternal care within and across animal taxa

Administration de metformine au cours de la gestation : conséquences sur l'appareil reproducteur des souriceaux mâles

National audienc

High cytotoxic and specific migratory potencies of senescent CD8+ CD57+ cells in HIV-infected and uninfected individuals

International audienceCD8+ CD57+ T lymphocytes, present at low levels in the peripheral blood of healthy individuals expand during HIV infection and remain elevated during chronic infection. Their role in the immune response remains unclear. We performed a large-scale gene array analysis (3158 genes) to characterize them and, interestingly, found no distinction in the transcriptional profiles of CD8+ CD57+ T lymphocytes from HIV-infected and uninfected subjects. In both groups, these cells showed specificity for multiple Ags and produced large amounts of IFN-gamma and TNF-alpha. The transcriptional profiles of CD8+ CD57+ and CD8+ CD57- cells, however, differed substantially. We propose that CD8+ CD57+ cells were Ag-driven effector cells with very high cytotoxic effector potential including perforin, granzymes, and granulysin, regardless of HIV status. At both the messenger and protein levels, they expressed more adhesion molecules and fewer chemokine receptors (CCR7 and CXCR4) than CD8+ CD57- cells but expressed preferentially CX3CR1. The lower expression level of genes involved in cell cycle regulation showed limited proliferation capacities of CD8+ CD57+ even in response to TCR and IL-2, IL-7, and IL-15 stimulation. CD8+ CD57+ T cells from both HIV and uninfected subjects maintain effective cytotoxic potentials but are destined to migrate to nonlymphoid tissues without further cycling

La signalisation FSH a-t-elle un sexe?

National audienc

Essential and redundant roles for Sox9 and Sox8 during testis development

International audienc

Essential and redundant roles for Sox9 and Sox8 during testis development

International audienc

Transgenic mice as a model to study the regulation of human transferrin expression in Sertoli cells

International audienc

Dynamic model of FSH signalling pathways in Sertoli cells adapted to two stages

International audienc