Identification, Isolation and Expansion of Myoendothelial Cells Involved in Leech Muscle Regeneration

Adult skeletal muscle in vertebrates contains myoendothelial cells that express both myogenic and endothelial markers, and which are able to differentiate into myogenic cells to contribute to muscle regeneration. In spite of intensive research efforts, numerous questions remain regarding the role of cytokine signalling on myoendothelial cell differentiation and muscle regeneration. Here we used Hirudo medicinalis (Annelid, leech) as an emerging new model to study myoendothelial cells and muscle regeneration. Although the leech has relative anatomical simplicity, it shows a striking similarity with vertebrate responses and is a reliable model for studying a variety of basic events, such as tissue repair. Double immunohistochemical analysis were used to characterize myoendothelial cells in leeches and, by injecting in vivo the matrigel biopolymer supplemented with the cytokine Vascular Endothelial Growth Factor (VEGF), we were able to isolate this specific cell population expressing myogenic and endothelial markers. We then evaluated the effect of VEGF on these cells in vitro. Our data indicate that, similar to that proposed for vertebrates, myoendothelial cells of the leech directly participate in myogenesis both in vivo and in vitro, and that VEGF secretion is involved in the recruitment and expansion of these muscle progenitor cells

The gut microbiota: a major player in the toxicity of environmental pollutants?

Exposure to environmental chemicals has been linked to various health disorders, including obesity, type 2 diabetes, cancer and dysregulation of the immune and reproductive systems, whereas the gastrointestinal microbiota critically contributes to a variety of host metabolic and immune functions. We aimed to evaluate the bidirectional relationship between gut bacteria and environmental pollutants and to assess the toxicological relevance of the bacteria–xenobiotic interplay for the host. We examined studies using isolated bacteria, faecal or caecal suspensions—germ-free or antibiotic-treated animals—as well as animals reassociated with a microbiota exposed to environmental chemicals. The literature indicates that gut microbes have an extensive capacity to metabolise environmental chemicals that can be classified in five core enzymatic families (azoreductases, nitroreductases, β-glucuronidases, sulfatases and β-lyases) unequivocally involved in the metabolism of >30 environmental contaminants. There is clear evidence that bacteria-dependent metabolism of pollutants modulates the toxicity for the host. Conversely, environmental contaminants from various chemical families have been shown to alter the composition and/or the metabolic activity of the gastrointestinal bacteria, which may be an important factor contributing to shape an individual’s microbiotype. The physiological consequences of these alterations have not been studied in details but pollutant-induced alterations of the gut bacteria are likely to contribute to their toxicity. In conclusion, there is a body of evidence suggesting that gut microbiota are a major, yet underestimated element that must be considered to fully evaluate the toxicity of environmental contaminants

Degradation of carbon disulphide (CS₂) in soils and groundwater from a CS_{2 -}contaminated site

This study is the first investigation of biodegradation of carbon disulphide (CS2) in soil that provides estimates of degradation rates and identifies intermediate degradation products and carbon isotope signatures of degradation. Microcosm studies were undertaken under anaerobic conditions using soil and groundwater recovered from CS2-contaminated sites. Proposed degradation mechanisms were validated using equilibrium speciation modelling of concentrations and carbon isotope ratios. A first-order degradation rate constant of 1. 25 × 10-2 h-1 was obtained for biological degradation with soil. Carbonyl sulphide (COS) and hydrogen sulphide (H2S) were found to be intermediates of degradation, but did not accumulate in vials. A 13C/12C enrichment factor of -7. 5 ± 0. 8 ‰ was obtained for degradation within microcosms with both soil and groundwater whereas a 13C/12C enrichment factor of -23. 0 ± 2. 1 ‰ was obtained for degradation with site groundwater alone. It can be concluded that biological degradation of both CS2-contaminated soil and groundwater is likely to occur in the field suggesting that natural attenuation may be an appropriate remedial tool at some sites. The presence of biodegradation by-products including COS and H2S indicates that biodegradation of CS2 is occurring and stable carbon isotopes are a promising tool to quantify CS2 degradation