Trophic position and individual feeding habits as drivers of differential PCB bioaccumulation in fish populations.

Despite PCBs being banned since the 1980's, some European peri-alpine lakes, and consequently their fish populations, are still contaminated by these xenobiotics. We investigated the relative contribution of physiological and trophic factors that could be implicated in fish PCB bioaccumulation in Lake Bourget (France), one of the most contaminated in Europe, by collecting Arctic char (n = 55) and European whitefish (n = 89) from 2013 to 2016. Concentrations of 7 indicator PCBs were 9-168 ng.g w.w-1 in whitefish and 90-701 ng.g w.w-1 in Arctic char. The fish trophic positions calculated from δ 15N values were positively correlated with PCB concentrations (r2 = 0.45; p < 0.001). A biomagnification model relying on TP and lipid content of fish was then designed, and it confirmed this result. A Bayesian mixing model based on δ 13C and δ 15N values was used to estimate the relative contribution of preys in the fish diet, which explained a significant proportion of the biomagnification model residuals (i.e., 17%). Zooplankton consumption was negatively correlated with PCB concentrations, whereas consumption of chironomids enhanced the PCB burden in fish. Correction of the biomagnification model for individual diets of fish increased the correlation between the predicted and measured fish PCB contents (R2 = 0.71; p < 0.001), highlighting the importance of fish feeding habits in the bioaccumulation process.

Microbiological characterization of 3193 French dwellings of Elfe cohort children.

Although exposure to indoor microorganisms in early life has already been associated with respiratory illness or allergy protection, only a few studies have performed standardized samplings and specific microbial analysis. Moreover, most do not target the different groups of microorganisms involved in respiratory diseases (fungi, bacteria, dust mites). In our study, ten specific qPCR targets (6 fungal species, 1 family and 2 genera of bacteria, 1 house dust mite) were used to analyze the microorganism composition of electrostatic dust fall collector (EDC) from 3193 dwellings of the Elfe French cohort study. Multivariate analyses allowed us to show that the microbial composition of dwellings, assessed with simultaneous analysis of 10 microorganisms, can be characterized by four entities: three bacteria, house dust mite Dermatophagoïdes pteronyssinus, fungi Alternaria alternata, and five other molds. Some dwellings' intrinsic characteristics (occupational ratio, type of dwelling and presence of pets) clearly influence microorganism distribution, and six different profiles of dwellings, characterized by their composition in microorganisms, have been described across France. The use of these clusters seems promising in the evaluation of allergic risk. Allergic respiratory diseases will develop in the near future in some children of the Elfe cohort and will indicate to what extent our approach can be predictive of respiratory disease.

The topology of the brown adipose tissue mitochondrial uncoupling protein determined with antibodies against its antigenic sites revealed by a library of fusion proteins.

The uncoupling protein (UCP) of brown adipose tissue mitochondria is a specialized member of the family of evolutionarily related mitochondrial membrane transporters, which also includes the ADP/ATP translocator and the phosphate carrier. We have generated a library of bacterial clones randomly expressing short subsequences of the UCP fused to the MalE periplasmic protein of Escherichia coli. Anti-UCP sera were used to select clones expressing antigenic sequences of the UCP. Ten different fusion proteins representing eight non-overlapping subsequences of the UCP were obtained. The ability of fusion proteins to select antibodies directed against a short segment of the UCP was used to study the topological organization of the UCP in the inner mitochondrial membrane. Four different fusion proteins were used to determine the orientation of the N-terminal extremities of the first, second, third and fourth predicted alpha-helices of the UCP. This topological study together with previous data on the UCP provides an experimental basis for the predicted structure of the UCP and for other homologous carrier proteins.

[Jejuno-jejunal invagination in polypoid lipoma producing renal failure]. / Invagination jéjuno-jéjunale sur lipome polypoïde entraînant une insuffisance rénale.

This is the case of a 43 years old woman with recurring epigastric pain for 8 years. She was hospitalized emergently for persistent vomiting causing acute renal failure. Numerous radiologic investigations prior to this hospitalisation showed no pathology. The diagnosis was made this time with a small bowel follow through. Intussusception of tumors is a known cause of small bowel obstruction. The clinical picture however, of severe vomiting causing acute renal failure on the basis of a proximal small bowel obstruction is exceptional.