Enhanced susceptibility of T lymphocytes to oxidative stress in the absence of the cellular prion protein.: PrPC and oxidative stress in T lymphocytes

International audienceThe cellular prion glycoprotein (PrP(C)) is ubiquitously expressed but its physiologic functions remain enigmatic, particularly in the immune system. Here, we demonstrate in vitro and in vivo that PrP(C) is involved in T lymphocytes response to oxidative stress. By monitoring the intracellular level of reduced glutathione, we show that PrP(-/-) thymocytes display a higher susceptibility to H(2)O(2) exposure than PrP(+/+) cells. Furthermore, we find that in mice fed with a restricted diet, a regimen known to increase the intracellular level of ROS, PrP(-/-) thymocytes are more sensitive to oxidative stress. PrP(C) function appears to be specific for oxidative stress, since no significant differences are observed between PrP(-/-) and PrP(+/+) mice exposed to other kinds of stress. We also show a marked evolution of the redox status of T cells throughout differentiation in the thymus. Taken together, our results clearly ascribe to PrP(C) a protective function in thymocytes against oxidative stress

The envelope of human endogenous retrovirus in neuro-inflammation

International audiencen.

Hedges and Woody Strips Browsing by Cattle on Pasture in Wallonia, Belgium

Shrub and tree forages are commonly used in animal production in many regions of the world. Nonetheless, in Western Europe, and especially in Wallonia in Belgium, hedges and woody strips have disappeared from the agricultural landscape over the past 60 years. Browse species are usually rich in plant secondary compounds such as tannins whose benefits on CH4 production and intestinal parasitism have been highlighted (Ramírez-Restrepo et al. 2010). Currently, agri-environmental measures taken by the Walloon government promote hedges and woody strips in pastures, raising the interest in browse species functionalities in ruminant production. This study aimed at: (1) determining the influence of the access to a hedge on the behaviour of cattle on pasture; and (2) evaluating the fermentability by rumen microbes of foliage of woody species promoted in the Walloon landscape

HIV-1 VPR impairs cell growth through the inactivation of two genetically distinct host cell proteins

International audiencen.

Relationship between humoral response against hepatitis C virus and disease overcome

International audienceConclusionHumoral response against hepatitis C virus linear epitopes is partly modified according to the disease state. This study highlights the importance of considering relative quantities of antibodies with different specificities rather than the amount of each antibody.Hepatitis C virus infection leads to liver disease whose severity can range from mild to serious lifelong illness. However the parameters involved in the evolution of the disease are still unknown. Among other factors, the virus-elicited antibody profile is suspected to play a role in the outcome of the disease. Analysis of the relationship between anti-virus antibodies and disease state requires the analysis of a large number of serums from patients (hepatitis C virus+) and of epitopes from the viral proteins. Such a study would benefit from microarray-based screening systems that are appropriate for high-throughput assays.We used a method combining peptide chips and surface plasmon resonance imaging previously shown to be suitable for analyzing complex mediums and detecting peptide-protein interactions. 56 peptides covering the entire viral proteome were grafted on chips and their interaction with antibodies present in the 68 injected serums from infected and non-infected donors was measured. Statistical analyses were conducted to determine a possible relationship between antibodies (specificity and amount) and disease states.A good discrimination between infected and non-infected donors validated our approach, and several correlations between antibodies profiles and clinical parameters have been identified. In particular, we demonstrated that ratios between particular antibodies levels allow for accurate discrimination of patients according to their pathologic states

A mathematical model for unsteady mixed flows in closed water pipes

We present the formal derivation of a new unidirectional model for unsteady mixed flows in non uniform closed water pipe. In the case of free surface incompressible flows, the \FS-model is formally obtained, using formal asymptotic analysis, which is an extension to more classical shallow water models. In the same way, when the pipe is full, we propose the \Pres-model, which describes the evolution of a compressible inviscid flow, close to gas dynamics equations in a nozzle. In order to cope the transition between a free surface state and a pressured (i.e. compressible) state, we propose a mixed model, the \PFS-model, taking into account changes of section and slope variation

A new role for complement C3: regulation of antigen processing through an inhibitory activity.

International audienceIncreasing evidence underlines the involvement of complement component C3 in the establishment of acquired immunity which appears to play a complex role and to act at different levels. As antigen proteolysis by antigen presenting cells is a key event in the control of antigen presentation efficiency, and consequently in the quality of the immune response, we investigated whether C3 could modulate this step. Our results demonstrate for the first time that C3 can interfere with antigen proteolysis: (i) proteolysis of tetanus toxin (TT) by the lysosomal fraction from a human monocytic cell line (U937) is impaired in the presence of C3, (ii) this effect is C3-specific and involves the C3c fragment of the protein, (iii) C3c is effective even after disulfide disruption, but none of its three constitutive peptides is individually accountable for this inhibitory effect and (iv) the target-protease(s) exhibit(s) a serine-protease activity. The physiological relevance of our results is demonstrated by experiments showing a subcellular colocalisation of TT and C3 after their uptake by U937 and the reduction of TT proteolysis once internalised together with C3. These results highlight a novel role for C3 that broadens its capacity to modulate acquired immune response

Is the behaviour of grazing cattle influenced by the presence of a hedge in the pasture?

The interest in using shrubs and trees as forage for cattle is raising in temperate regions, along with the environmental measures promoting hedges along pasture. This study aimed at determining the influence of the presence of a woody hedge on grazing cattle behavior as well as the evolution of this behavior during the grazing season. Twelve heifers were set to graze a standard ryegrass and clover meadow during the grazing season of 2013. The animals were divided in 2 groups : one with a free access to a hedge composed by 10 temperate shrub and tree species, the other with no access to a hedge (control). Their behavior (grazing, browsing and other activities) was monitored during 14h d-1 replicated 3d week-1 during 3 periods (May, July and September). Results suggest that both season and presence of a hedge have an influence on the behavior of heifers. Grazing, resting and rumination varied between the two groups in each period (P<0.05). The time spent browsing was influenced by the season (P<0.001); the heifers with an access to the hedge could browse 19.3% of the total time in May against 5.9 and 5.4% in July and September. Both control and experimental heifers grazed more with the progressing season, but the animals without the hedge grazed always more than the heifers that could graze and browse (49.6 vs 43.0%). In conclusion, browsing woody species represents a significant part of the time spent for forage ingestion, and variation in this behavior over the whole grazing season requires to investigate the influence of both pasture and browse availability and composition

Consid\ue9rations sur la syst\ue9matique des Phoronidiens. VII. Phoronis australis Haswell, 1883

Volume: 41Start Page: 1244End Page: 125

Effects on performance and meat characteristics of a diet supplemented with fat during the finishing period of growing fattening bulls

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