Experimental colitis in SIV-uninfected rhesus macaques recapitulates important features of pathogenic SIV infection

Mucosal damage to the gastrointestinal (GI) tract with resulting microbial translocation is hypothesized to significantly contribute to the heightened and persistent chronic inflammation and immune activation characteristic to HIV infection. Here we employ a non-human primate model of chemically induced colitis in SIV-uninfected rhesus macaques that we developed using dextran sulfate sodium (DSS), to directly test this hypothesis. DSS treatment results in GI barrier damage with associated microbial translocation, inflammation and immune activation. The progression and severity of colitis are longitudinally monitored by a magnetic resonance imaging approach. DSS treatment of SIV-infected African green monkeys, a natural host species for SIV that does not manifest GI tract damage or chronic immune activation during infection, results in colitis with elevated levels of plasma SIV RNA, sCD14, LPS, CRP and mucosal CD4+ T-cell loss. Together these results support the hypothesis that GI tract damage leading to local and systemic microbial translocation, and associated immune activation, are important determinants of AIDS pathogenesis

GH overexpression causes muscle hypertrophy independent from local IGF-I in a zebrafish transgenic model

The aim of the present study was to analyse the morphology of white skeletal muscle in males and females from the GH-transgenic zebrafish(Danio rerio) lineage F0104, comparing the expression of genes related to the somatotrophic axis and myogenesis. Histological analysis demonstrated that transgenic fish presented enhanced muscle hypertrophy when compared to non-transgenic fish, with transgenic females being more hypertrophic than transgenic males. The expression of genes related to muscle growth revealed that transgenic hypertrophy is independent from local induction of insulin-like growth factor 1 gene (igf1). In addition, transgenic males exhibited significant induction of myogenin gene (myog) expression, indicating that myog may mediate hypertrophic growth in zebrafish males overexpressing GH. Induction of the a-actin gene (acta1) in males, independently from transgenesis, also was observed. There were no significant differences in total protein content from the muscle. Our results show that muscle hypertrophy is independent from muscle igf1, and is likely to be a direct effect of excess circulating GH and/or IGF1 in this transgenic zebrafish lineage

How Variable Is a Primate’s World: Spatial and Temporal Variation in Potential Ecological Drivers of Behaviour ?

International audience"The field of primatology has reached the stage where there are sufficient long-term studies and many shorter investigations on the same species at many different locations, in which we are able to appreciate how variable the behaviour of primates can be and how predictable their environment is over space and time. For example, redtail monkeys (Cercopithecus ascanius) exhibit extreme flexibility in diet; i.e. within the same national park, the amount of time they spend eating fruit varies from 36 to 60% of their foraging time, and among populations, time spent eating fruit ranges from 13 to 61%. Similarly, long-term phenological data from the same area encompassing over two decades illustrate that fruit availability can vary among years by as much as eightfold. While data have steadily accumulated on how variable primate behaviour and proposed environmental predictors of behaviour can be, this information has not been used to effectively re-evaluate theory. For example, current primate socioecological theory has derived general frameworks using the average behavioural traits of species or genera, but these new data suggest it is inappropriate to use such averages. Similarly, environments have often been characterized by single studies of 2 years or less, which does not sufficiently account for environmental variation. Here, we present examples of behavioural and ecological variation and consider ways that our field could advance in the future by considering this variation." (source éditeur