Muscular Weakness in Individuals with HIV Associated with a Disorganization of the Cortico-Spinal Tract: A Multi-Modal MRI Investigation

Motor impairment is highly prevalent in HIV-infected patients. Here, we assess associations between peripheral muscular deficits as evaluated by the 5 sit-to-stand test (5STS) and structural integrity of the motor system at a central level. Eighty-six HIV-infected patients receiving combination antiretroviral therapy and with no major cerebral events, underwent an MRI scan and the 5STS. Out of 86 participants, forty presented a score greater than two standard deviations above mean normative scores calculated for the 5STS and were therefore considered as motor-impaired. MRI-structural cerebral parameters were compared to the unimpaired participants. Fractional Anisotropy (FA), Axial Diffusivity (AD) and Radial Diffusivity (RD), reflecting microstructural integrity, were extracted from Diffusion-Tensor MRI. Global and regional cerebral volumes or thicknesses were extracted from 3D-T1 morphological MRI. Whereas the two groups did not differ for any HIV variables, voxel-wise analysis revealed that motor-impaired participants present low FA values in various cortico-motor tracts and low AD in left cortico-spinal tract. However, they did not present reduced volumes or thicknesses of the precentral cortices compared to unimpaired participants. The absence of alterations in cortical regions holding motor-neurons might argue against neurodegenerative process as an explanation of White Matter (WM) disorganization.     

Isolation and identification of pathogenic microorganisms at wastewater-irrigated fields: ratios in air and wastewater

Samples of air and corresponding wastewater samples were taken at wastewater spray-irrigated fields. The concentrations of salmonellae and enteroviruses present in these samples were determined and compared with those of coliforms, and the ratios between them were calculated. The most common Salmonella serotype in the air was Salmonella ohio, whereas in the wastewater, Salmonella anatum was the most common. Enteroviruses isolated and identified were poliovirus, echovirus, and coxsackievirus type B. From the ratios of salmonellas to coliforms and enteroviruses to coliforms in the air, as compared to these ratios in the wastewater, it was concluded that the suitability of coliforms as an indication of airborne contamination caused by spray irrigation is questionable.     

Characterization of Mg2+-induced conformational change in the 50S ribosomal subunit by differential hydrogen exchange.

The technique of differential hydrogen exchange allows detection of a conformational change in the 50S subunit of Escherichia coli ribosome when the magnesium concentration is lowered in a range where ribosomal activity is fully preserved. This change is characterized by a seventy-fold acceleration of about thirty labile hydrogens in the case of a Mg2+ jump from 10 mM to 2 mM. The small number of hydrogens involved can explain the difficulty in detecting this change by other methods.     

Fluctuating selection and its (elusive) evolutionary consequences in a wild rodent population

Temporal fluctuations in the strength and direction of selection are often proposed as a mechanism that slows down evolution, both over geological and contemporary timescales. Both the prevalence of fluctuating selection and its relevance for evolutionary dynamics remain poorly understood however, especially on contemporary timescales: unbiased empirical estimates of variation in selection are scarce, and the question of how much of the variation in selection translates into variation in genetic change has largely been ignored. Using long‐term individual‐based data for a wild rodent population, we quantify the magnitude of fluctuating selection on body size. Subsequently, we estimate the evolutionary dynamics of size and test for a link between fluctuating selection and evolution. We show that, over the past 11 years, phenotypic selection on body size has fluctuated significantly. However, the strength and direction of genetic change have remained largely constant over the study period; that is, the rate of genetic change was similar in years where selection favoured heavier vs. lighter individuals. This result suggests that over shorter timescales, fluctuating selection does not necessarily translate into fluctuating evolution. Importantly however, individual‐based simulations show that the correlation between fluctuating selection and fluctuating evolution can be obscured by the effect of drift, and that substantially more data are required for a precise and accurate estimate of this correlation. We identify new challenges in measuring the coupling between selection and evolution, and provide methods and guidelines to overcome them.     

Vitamin D limits inflammation-linked microRNA expression in adipocytes in vitro and in vivo: A new mechanism for the regulation of inflammation by vitamin D

Inflammation of adipose tissue is believed to be a contributing factor to many chronic diseases associated with obesity. Vitamin D (VD) is now known to limit this metabolic inflammation by decreasing inflammatory marker expression and leukocyte infiltration in adipose tissue. In this study, we investigated the impact of VD on microRNA (miR) expression in inflammatory conditions in human and mouse adipocytes, using high-throughput methodology (miRNA PCR arrays). Firstly, we identified three miRs (miR-146a, miR-150, and miR-155) positively regulated by TNFα in human adipocytes. Interestingly, the expression of these miRs was strongly prevented by 1,25(OH)₂D preincubation. These results were partly confirmed in 3T3-L1 adipocytes (for miR-146a and miR-150). The ability of VD to control the expression of these miRs was confirmed in diet-induced obese mice: the levels of the three miRs were increased following high fat (HF) diet in epididymal white adipose tissue and reduced in HF diet fed mice supplemented with VD. The involvement of NF-κB signaling in the induction of these miRs was confirmed in vitro and in vivo using aP2-p65 transgenic mice. Finally, the ability of VD to deactivate NF-κB signaling, via p65 and IκB phosphorylation inhibition in murine adipocyte, was observed and could constitute a driving molecular mechanism. This study demonstrated for the first time that VD modulates the expression of miRs in adipocytes in vitro and in adipose tissue in vivo through its impact on NF-κB signaling pathway, which could represent a new mechanism of regulation of inflammation by VD.     

Settlement pattern of tortoises translocated into the wild: a key to evaluate population reinforcement success

A lack of long-term monitoring often impedes the evaluation of translocation used to reinforce populations. Crucial questions regarding the exact timing and place of possible settlement remain unanswered. To examine these issues we radio-tracked during three years 24 tortoises (Testudo hermanni hermanni) released to reinforce a resident population impacted by fire. Individuals from the resident population (N = 20) and from a distant control population (N = 11) were also radio-tracked. More than 11,000 fixes were collected, enabling us to precisely describe movement patterns. Most translocated tortoises first dispersed (> 500 m to > 3000 m away) in a random direction and sometimes crossed unfavorable areas. Later, a marked shift in movement pattern, from a relatively unidirectional course to multidirectional displacements indicated settlement. Movement patterns of translocated and resident individuals became undistinguishable after settlement. Most individuals settled during the first year after release but several settled in the second year. Mean annual survival rate (> 85%) remained within the range of the species but was lower compared to the resident (93%) and control tortoises (100%). Overall, most translocated individuals (~ 63%) settled and adapted well to their novel environment. This result is essential regarding current controversies that are unfounded and that limit conservation translocations. Yet, translocation sites should be large enough and/or surrounded by secondary favorable areas to limit the mortality associated with dispersal in hazardous environments. Large numbers of individuals rescued during urbanization works may easily supply conservation translocations to reinforce fragile populations.     

Diet-induced obesity and associated disorders are prevented by natural bioactive type 1 fish collagen peptides (Naticol®) treatment

To fight against metabolic disorders such as insulin resistance, new alimentary behaviors are developed. For instance, hyperproteined, gluten-free, or collagen-enriched diets could be preconized in order to reduce the consequences of obesity. In this aim, this study evaluates the potential effects of warm sea fish collagen peptides (Naticol®) on representative metabolic and inflammatory parameters. For that, male C57Bl6/J mice fed with either a chow- (CD) or high-fat diet (HFD) were submitted or not to specific collagen peptides in drinking water (4 g/kg bw/d) for 20 weeks. Weight, body composition, glucose tolerance, and insulin sensitivity were followed up. Effects of fish collagen peptides on various blood parameters reflecting the metabolism status were also measured (free fatty acids, triglycerides, cholesterol, hormones) together with adipocyte inflammation. Results showed that HFD-fed mice supplemented by fish collagen peptides exhibited a significant lower increase in body weight as soon as the twelfth week of treatment whereas no effect of the peptide was observed in CD fed mice. In line with this result, a weaker increase in fat mass in HFD-fed mice supplemented with Naticol® at both 9 and 18 weeks of treatment was also observed. In spite of this resistance to obesity promoted by fish collagen peptides treatment, no difference in glucose tolerance was found between groups whereas mice treated with Naticol® exhibited a lower basal glycemia. Also, even if no effect of the treatment on adipocyte lipolysis was found, a decrease of inflammatory cytokines was retrieved in collagen-supplemented group arguing for a potential better insulin sensitivity. Altogether, these results need to be completed but are the first describing a benefic role of warm sea fish collagen peptides in a context of metabolic disease paving the route for a potential utilization in human obesity-associated disorders.