Biomonitoring of the genotoxic potential (micronucleus assay) and detoxifying activity (EROD induction) in the River Dadou (France), using the amphibian Xenopus laevis

Within the framework of a general survey of the water quality of the river Dadou (Tarn, France), different physicochemical parameters were measured and an inventory of the fish population was made along the water course, around the Rassisse dam.With the aim of monitoring the potential genotoxic effects and the detoxifying activities induced in organisms exposed to the river water, two in vivo bioassays were performed in laboratory experiments, using larvae of the amphibian Xenopus laevis.The first was the micronucleus test, using red blood cells, and the second the assay of ethoxyresorufin-O-deethylase (EROD) induction in the liver of exposed animals.Eight water samples were taken from the river and at outlet points from the two major industrial activities of the studied section of the water course: a spar-fluor mine and a water treatment plant.Genotoxic impact and EROD induction were measured in the larvae.The effluent of the filter-washing process from the water treatment plant was found to be particularly genotoxic, even after dilution in pure reconstituted water, but no particular genotoxicity was found, either in Dadou river water, or in the effluents from the mine.On the other hand, most of the water samples tested produced a clear induction of EROD activity compared to the level of enzymatic activity found in the liver of larvae reared in the river water sampled upstream of the industrial activities.These results were interpreted taking into account (i) the high concentrations of pollutants (fluorine and manganese) measured in the river water, (ii) the very low population levels inventoried in the downstream section of the river and (iii) the possible interactions between the substances present in the river water, particularly the classical EROD inducers PAHs and PCBs

Comparative genomics of Mycoplasma feriruminatoris, a fast-growing pathogen of wild Caprinae.

Mycoplasma feriruminatoris is a fast-growing Mycoplasma species isolated from wild Caprinae and first described in 2013. M. feriruminatoris isolates have been associated with arthritis, kerato conjunctivitis, pneumonia and septicemia, but were also recovered from apparently healthy animals. To better understand what defines this species, we performed a genomic survey on 14 strains collected from free-ranging or zoo-housed animals between 1987 and 2017, mostly in Europe. The average chromosome size of the M. feriruminatoris strains was 1,040±0,024 kbp, with 24 % G+C and 852±31 CDS. The core genome and pan-genome of the M. feriruminatoris species contained 628 and 1312 protein families, respectively. The M. feriruminatoris strains displayed a relatively closed pan-genome, with many features and putative virulence factors shared with species from the M. mycoides cluster, including the MIB-MIP Ig cleavage system, a repertoire of DUF285 surface proteins and a complete biosynthetic pathway for galactan. M. feriruminatoris genomes were found to be mostly syntenic, although repertoires of mobile genetic elements, including Mycoplasma Integrative and Conjugative Elements, insertion sequences, and a single plasmid varied. Phylogenetic- and gene content analyses confirmed that M. feriruminatoris was closer to the M. mycoides cluster than to the ruminant species M. yeatsii and M. putrefaciens. Ancestral genome reconstruction showed that the emergence of the M. feriruminatoris species was associated with the gain of 17 gene families, some of which encode defence enzymes and surface proteins, and the loss of 25 others, some of which are involved in sugar transport and metabolism. This comparative study suggests that the M. mycoides cluster could be extended to include M. feriruminatoris. We also find evidence that the specific organization and structure of the DnaA boxes around the oriC of M. feriruminatoris may contribute to drive the remarkable fast growth of this minimal bacterium