Serological survey of feline viral pathogens in free-living European wildcats (Felis s. silvestris) from Luxembourg.

European populations of free-living wildcats have been shown to be exposed to cat viruses. Luxembourg has a high degree of habitat fragmentation, and hybridisation rates between domestic cats and wildcats are high. We therefore assessed the seroprevalence of six viruses in 34 serum samples collected between 2001 and 2016 from wildcats in Luxembourg. The values for feline leukemia virus (FeLV; 52.9%) and feline coronavirus (FCoV; 47.1%) were amongst the highest reported for wildcats. We found evidence for the cumulative likelihood of exposure to FCoV affecting its seroprevalence. Routine monitoring of viral agents in this strictly protected species should be considered.

Against All Odds: Trehalose-6-Phosphate Synthase and Trehalase Genes in the Bdelloid Rotifer Adineta vaga Were Acquired by Horizontal Gene Transfer and Are Upregulated during Desiccation.

The disaccharide sugar trehalose is essential for desiccation resistance in most metazoans that survive dryness; however, neither trehalose nor the enzymes involved in its metabolism have ever been detected in bdelloid rotifers despite their extreme resistance to desiccation. Here we screened the genome of the bdelloid rotifer Adineta vaga for genes involved in trehalose metabolism. We discovered a total of four putative trehalose-6-phosphate synthase (TPS) and seven putative trehalase (TRE) gene copies in the genome of this ameiotic organism; however, no trehalose-6-phosphate phosphatase (TPP) gene or domain was detected. The four TPS copies of A. vaga appear more closely related to plant and fungi proteins, as well as to some protists, whereas the seven TRE copies fall in bacterial clades. Therefore, A. vaga likely acquired its trehalose biosynthesis and hydrolysis genes by horizontal gene transfers. Nearly all residues important for substrate binding in the predicted TPS domains are highly conserved, supporting the hypothesis that several copies of the genes might be functional. Besides, RNAseq library screening showed that trehalase genes were highly expressed compared to TPS genes, explaining probably why trehalose had not been detected in previous studies of bdelloids. A strong overexpression of their TPS genes was observed when bdelloids enter desiccation, suggesting a possible signaling role of trehalose-6-phosphate or trehalose in this process.

Bacterial community composition in three freshwater reservoirs of different alkalinity and trophic status.

In order to investigate the factors controlling the bacterial community composition (BCC) in reservoirs, we sampled three freshwater reservoirs with contrasted physical and chemical characteristics and trophic status. The BCC was analysed by 16S rRNA gene amplicon 454 pyrosequencing. In parallel, a complete dataset of environmental parameters and phytoplankton community composition was also collected. BCC in the analysed reservoirs resembled that of epilimnetic waters of natural freshwater lakes with presence of Actinobacteria, Alpha- and Betaproteobacteria, Cytophaga-Flavobacteria-Bacteroidetes (CFB) and Verrucomicrobia groups. Our results evidenced that the retrieved BCC in the analysed reservoirs was strongly influenced by pH, alkalinity and organic carbon content, whereas comparatively little change was observed among layers in stratified conditions.

Genetic structure of fragmented southern populations of African Cape buffalo (Syncerus caffer caffer).

BACKGROUND: African wildlife experienced a reduction in population size and geographical distribution over the last millennium, particularly since the 19th century as a result of human demographic expansion, wildlife overexploitation, habitat degradation and cattle-borne diseases. In many areas, ungulate populations are now largely confined within a network of loosely connected protected areas. These metapopulations face gene flow restriction and run the risk of genetic diversity erosion. In this context, we assessed the "genetic health" of free ranging southern African Cape buffalo populations (S.c. caffer) and investigated the origins of their current genetic structure. The analyses were based on 264 samples from 6 southern African countries that were genotyped for 14 autosomal and 3 Y-chromosomal microsatellites. RESULTS: The analyses differentiated three significant genetic clusters, hereafter referred to as Northern (N), Central (C) and Southern (S) clusters. The results suggest that splitting of the N and C clusters occurred around 6000 to 8400 years ago. Both N and C clusters displayed high genetic diversity (mean allelic richness (A r ) of 7.217, average genetic diversity over loci of 0.594, mean private alleles (P a ) of 11), low differentiation, and an absence of an inbreeding depression signal (mean F IS = 0.037). The third (S) cluster, a tiny population enclosed within a small isolated protected area, likely originated from a more recent isolation and experienced genetic drift (F IS = 0.062, mean A r = 6.160, P a = 2). This study also highlighted the impact of translocations between clusters on the genetic structure of several African buffalo populations. Lower differentiation estimates were observed between C and N sampling localities that experienced translocation over the last century. CONCLUSIONS: We showed that the current genetic structure of southern African Cape buffalo populations results from both ancient and recent processes. The splitting time of N and C clusters suggests that the current pattern results from human-induced factors and/or from the aridification process that occurred during the Holocene period. The more recent S cluster genetic drift probably results of processes that occurred over the last centuries (habitat fragmentation, diseases). Management practices of African buffalo populations should consider the micro-evolutionary changes highlighted in the present study.

Genetic uniformity and long-distance clonal dispersal in the invasive androgenetic Corbicula clams.

The clam genus Corbicula is an interesting model system to study the evolution of reproductive modes as it includes both sexual and asexual (androgenetic) lineages. While the sexual populations are restricted to the native Asian areas, the androgenetic lineages are widely distributed being also found in America and Europe where they form a major aquatic invasive pest. We investigated the genetic diversity of native and invasive Corbicula populations through a worldwide sampling. The use of mitochondrial and nuclear (microsatellite) markers revealed an extremely low diversity in the invasive populations with only four, undiversified, genetic lineages distributed across Europe and America. On the contrary, in the native populations, both sexual and androgenetic lineages exhibited much higher genetic diversity. Remarkably, the most abundant and widely distributed invasive forms, the so-called form A and form R found in America and Europe respectively, are fixed for the same single COI (cytochrome c oxydase subunit I) haplotype and same multilocus genotype. This suggests that form R, observed in Europe since the 1980s, derived directly from form A found in America since the 1920s. In addition, this form shares alleles with some Japanese populations, indicating a Japanese origin for this invasive lineage. Finally, our study suggests that few androgenetic Corbicula individuals successfully invaded the non-native range and then dispersed clonally. This is one striking case of genetic paradox raising the issue of invasive and evolutionary success of genetically undiversified populations.

Identification and characterization of a novel multicopper oxidase from Acidomyces acidophilus with ferroxidase activity.

A new multicopper oxidase gene AaMco1 was identified in Acidomyces acidophilus, a pigmented extremophile ascomycete originally isolated from acidic water. Sequence analysis revealed that it encodes a 682 amino acid protein with an apparent molecular mass of 85 kDa as determined by denaturing SDS-PAGE. Interestingly, AaMco1 has a predicted N-terminal transmembrane helix and no signal peptide. To obtain an active and soluble protein, AaMco1 was truncated at its N-terminal to remove the transmembrane helix, but even in this form the protein was found in the insoluble fraction. AaMco1 and its truncated form were then denatured, purified and renatured before characterization. Structural analysis and protein characterization by enzymatic assays indicate that AaMco1 has ferroxidase activity. AaMco1 is also able to oxidize the DMPPDA compound and could be part of a new phylogenetic cluster, the ascomycete MCOs family, described for the first time here.

Phylogeny and androgenesis in the invasive Corbicula clams (Bivalvia, Corbiculidae) in Western Europe.

BACKGROUND: The genus Corbicula is one of the most invasive groups of molluscs. It includes both sexual and androgenetic lineages. The present study re-assessed the different morphotypes and haplotypes of West European Corbicula in order to clarify their taxonomic identification and phylogenetic relationships with American and Asian Corbicula clams. We studied several populations from West European river basins (Meuse, Seine, Rhine and Rhône) through an "integrative taxonomy" approach. We combined morphology, partial mitochondrial COI and cyt b sequences and eleven microsatellite loci. Furthermore, we looked for discrepancies between mtDNA and nrDNA/morphology, indicative of androgenesis between lineages. RESULTS: There are three Corbicula morphotypes in Western Europe associated to three mitochondrial lineages and three genotypes. Form R shares the same COI haplotype as the American form A and the Japanese C. leana. Form S and the American form C have the same haplotype, although their morphologies seem divergent. The European form Rlc belongs to the same mitochondrial lineage as both the American form B and the Asian C. fluminea.Interestingly, within each haplotype/genotype or lineage, no genetic diversity was found although their invasive success is high. Moreover, we detected rare mismatches between mtDNA and nrDNA/morphology, indicative of androgenesis and mitochondrial capture between form R and form S and therefore challenging the phylogenetic relatedness and the species status within this genus. The global phylogenetic analysis revealed that the sexual Corbicula lineages seem restricted to the native areas while their androgenetic relatives are widespread and highly invasive. CONCLUSIONS: We clarified the discrepancies and incongruent results found in the literature about the European morphotypes of Corbicula and associated mitochondrial lineages. The three West European morphotypes belong to three distinct nuclear and mitochondrial lineages. However mitochondrial capture occurs in sympatric populations of forms R and S. The species status of the morphotypes therefore remains doubtful. Moreover the androgenetic lineages seem widely distributed compared to their sexual relatives, suggesting that androgenesis and invasive success may be linked in the genus Corbicula.

Bcl-2 and Caspase 3 mRNA levels in the testes of gudgeon, Gobio gobio, exposed to ethinylestradiol (EE2).

Apoptosis inhibition has been reported in the male reproductive tract of teleost fish exposed to 17beta-estrogen or estrogen-like compounds. In order to understand the molecular mechanisms of cell death inhibition, this study examined 2 genes involved in the apoptotic pathway, Bcl-2 and Caspase 3, an anti-apoptotic and a pro-apoptotic genes, respectively. Partial cDNA sequences of Bcl-2 and Caspase 3 were cloned from gudgeon (Gobio gobio), a common European cyprinid fish. To follow mRNA levels of Bcl-2 and Caspase 3 under xenoestrogen exposure, we first performed an in vitro experiment on fish testis exposed to the most potent xenoestrogen found in the environment, ethinylestradiol (EE2). We further studied mRNA expression of both genes in the testis of fish exposed to xenoestrogens in situ. In the in vitro experiment, fragments of gudgeon testis were exposed for 21 days to 10(-3), 10(-2), 10(-1), 1 and 10 microg/L of EE2, as well as to positive (10(-1) microg/L of E2) and ethanol control medium. Results showed a significant induction of Bcl-2 mRNA at 10(-1) microg/L (p<0.05). Surprisingly, Caspase 3, a cell death effector, displayed the same profile as observed for the anti-apoptotic gene Bcl-2. In the experiment on wild gudgeon exposed from birth to an estrogenic sewage treatment plant effluent, the mRNA expression of Bcl-2 and Caspase 3 in feminized fish (ovotestis) was not significantly different due to high variability of expression between individuals. At the current state of knowledge on spermatogenesis disruption in teleost fish, in vitro studies seem better adapted than in situ investigations to enlighten the molecular pathway of apoptosis inhibition in testis exposed to xenoestrogens.