Influence of eye closing on the cardiovascular response to stand test on stable and unstable platforms

Check if the stimulation of the leg muscles and neuro-sensorial system during stand test influence the cardiovascular response to stand test pre and post a 7 d HDT (4 subjects). Methods: After 20 min supine, the subject stood for 10 min, and closed the eyes for 1 min. Then he stayed 2 min stand up on ant-posterior or lateral unstable platform and closed the eyes for 30 sec. The cerebral and lower limb flow were assessed by Doppler (skin fixed sensors) and also the cerebral to femoral flow ratio (CFR). Results: All 4 subjects were tolerant, CFR increased similarly pre and post HDT. Post HDT eye closing increased leg muscle activity, and femoral flow increased more than pre HDT, on ant-post unstable platform. The trace of the body foot pressure point was much longer post HDT on the ant-post platform. Conclusion: Post HDT neuro-sensorial disadaptation may contribute to reduce the orthostatic tolerance at least in absence of visual references.     

New in vivo and ex vivo models for the experimental study of sheep scrapie: development and perspectives

Sheep scrapie is a prototypical transmissible spongiform encephalopathy (TSE), and the most widespread of these diseases. Experimental study of TSE infectious agents from sheep and other species essentially depends on bioassays in rodents. Transmission of natural sheep scrapie to conventional mice commonly requires one or two years. In an effort to develop laboratory models in which investigations on the sheep TSE agent would be facilitated, we have established mice and cell lines that were genetically engineered to express ovine PrP protein and examined their susceptibility to the infection. A series of transgenic mice lines (tgOv) expressing the high susceptibility allele (VRQ) of the ovine PrP gene from different constructs was expanded. Following intracerebral inoculation with natural scrapie isolates, all animals developed typical TSE neurological signs and accumulated abnormal PrP in their brain. The survival time in the highest expressing tgOv lines ranged from 2 to 7 months, depending on the isolate. It was inversely related to the brain PrP content, and essentially unchanged on further passaging. Ovine PrP transgene expression thus enhanced scrapie disease transmission from sheep to mice. Such tgOv mice may bring new opportunities for analysing the natural variation of scrapie strains and measuring infectivity. As no relevant cell culture models for agents of naturally-occurring TSE exist, we have explored various strategies in order to obtain stable cell lines that would propagate the sheep agent ex vivo without prior adaptation to rodent. In one otherwise refractory rabbit epithelial cell line, a regulable expression of ovine PrP was achieved and found to enable an efficient replication of the scrapie agent in inoculated cultures. Cells derived from sheep embryos or from tgOv mice were also used in an attempt to establish permissive cell lines derived from the nervous system. Cells engineered to express PrP proteins of a specified sequence may thus represent a promising strategy to further explore, at the cellular level, various aspects of TSE diseases.     

The contrasting effects of short‐ and long‐term habitat drainage on the population dynamics of freshwater turtles in a human‐dominated landscape

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Genetic analysis of durable resistance to yellow rust in bread wheat

Yellow rust, caused by Puccinia striiformis, is one of the most damaging diseases affecting bread wheat in temperate regions. Although resistance to yellow rust is frequently overcome by new virulent races, a durable form of resistance in the French bread wheat Camp Rémy (CR) has remained effective since its introduction in 1980. We used 217 F₇ recombinant inbred lines (RILs) derived from the cross between CR and the susceptible cultivar Récital to identify and map quantitative trait loci (QTLs) involved in durable yellow rust resistance. Six significant QTLs that were stable over a 4-year period were detected. Two QTLs, denoted QYr.inra-2DS and QYr.inra-5BL.2, were located on the short arm of chromosome 2D and the long arm of chromosome 5B, respectively. Each explained on average 25–35% of the observed phenotypic variation and were probably inherited from Cappelle Desprez, a parent of CR that confers durable adult plant resistance to yellow rust. QYr.inra-2DS probably corresponds to the Yr16 gene. The most consistent QTL, designated QYr.inra-2BL, was located on the centromeric region of chromosome 2B and explained 61% of the phenotypic variation in 2003. This QTL was responsible for seedling-stage resistance and may correspond to a cluster of genes, including Yr7. The remaining QTLs were mapped to the short arm of chromosome 2B (R²=22–70%) and to the long arm of chromosomes 2A (R²=0.20–0.40) and 5B (R²=0.18–0.26). This specific combination of seedling and adult plant resistance genes found in CR and CD may constitute the key to their durable resistance against yellow rust.     

The Spread of Aedes albopictus in Metropolitan France: Contribution of Environmental Drivers and Human Activities and Predictions for a Near Future

Invasion of new territories by insect vector species that can transmit pathogens is one of the most important threats for human health. The spread of the mosquito Aedes albopictus in Europe is emblematic, because of its major role in the emergence and transmission of arboviruses such as dengue or chikungunya. Here, we modeled the spread of this mosquito species in France through a statistical framework taking advantage of a long-term surveillance dataset going back to the first observation of Ae. albopictus in the Metropolitan area. After validating the model, we show that human activities are especially important for mosquito dispersion while land use is a major factor for mosquito establishment. More importantly, we show that Ae. albopictus invasion is accelerating through time in this area, resulting in a geographic range extending further and further year after year. We also show that sporadic “jump” of Ae. albopictus in a new location far from the colonized area did not succeed in starting a new invasion front so far. Finally, we discuss on a potential adaptation to cooler climate and the risk of invasion into Northern latitudes.     

IL-33-Mediated Protection against Experimental Cerebral Malaria Is Linked to Induction of Type 2 Innate Lymphoid Cells,M2 Macrophages and Regulatory T Cells

Cerebral malaria (CM) is a complex parasitic disease caused by Plasmodium sp. Failure to establish an appropriate balance between pro- and anti-inflammatory immune responses is believed to contribute to the development of cerebral pathology. Using the blood-stage PbA (Plasmodium berghei ANKA) model of infection, we show here that administration of the pro-Th2 cytokine, IL-33, prevents the development of experimental cerebral malaria (ECM) in C57BL/6 mice and reduces the production of inflammatory mediators IFN-γ, IL-12 and TNF-α. IL-33 drives the expansion of type-2 innate lymphoid cells (ILC2) that produce Type-2 cytokines (IL-4, IL-5 and IL-13), leading to the polarization of the anti-inflammatory M2 macrophages, which in turn expand Foxp3 regulatory T cells (Tregs). PbA-infected mice adoptively transferred with ILC2 have elevated frequency of M2 and Tregs and are protected from ECM. Importantly, IL-33-treated mice deleted of Tregs (DEREG mice) are no longer able to resist ECM. Our data therefore provide evidence that IL-33 can prevent the development of ECM by orchestrating a protective immune response via ILC2, M2 macrophages and Tregs.     

Cadmium hyperaccumulation and reproductive traits in natural Thlaspi caerulescens populations

During the last decade, the metal hyperaccumulating plants have attracted considerable attention because of their potential use in decontamination of heavy metal contaminated soils. However, in most species, little is known regarding the function, the ecological and the evolutionary significances of hyperaccumulation. In our study, we investigated the parameters influencing the Cd concentration in plants as well as the biological implications of Cd hyperaccumulation in nine natural populations of Thlaspi caerulescens. First, we showed that Cd concentration in the plant was positively correlated with plant Zn, Fe, and Cu concentrations. This suggested that the physiological and/or molecular mechanisms for uptake, transport and/or accumulation of these four heavy metals interact with each other. Second, we specified a measure of Cd hyperaccumulation capacity by populations and showed that T. caerulescens plants originating from populations with high Cd hyperaccumulation capacity had better growth, by developing more and bigger leaves, taller stems, and produced more fruits and heavier seeds. These results suggest a tolerance/disposal role of Cd hyperaccumulation in this species.