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Volff J.-N.,CNRS Lyon Institute of Functional Genomics | Volff J.-N.,University of Würzburg | Selz Y.,University of Würzburg | Hoffmann C.,University of Würzburg | And 18 more authors.
Genetics | Year: 2013

In two swordtail species of the genus Xiphophorus, the onset of puberty has been shown to be modulated at the P locus by sequence polymorphism and gene copy-number variation affecting the type 4 melanocortin hormone receptor Mc4r. The system works through the interaction of two allelic types, one encoding wild type and the other dominant-negative receptors. We have analyzed the structure and evolution of the P locus in the platyfish Xiphophorus maculatus, where as many as nine alleles of P determining the onset of sexual maturity in males and females, fecundity in females, and adult size in males are located on both the X and Y chromosomes in a region linked to the master sex-determining locus. In this species, mc4r has been amplified to up to 10 copies on both the X and Y chromosomes through recent large serial duplications. Subsequently, mc4r paralogues have diverged considerably into many different subtypes. Certain copies have acquired new untranslated regions through genomic rearrangements, and transposable element insertions and other mutations have accumulated in promoter regions, possibly explaining observed deviations from the classical mc4r transcriptional pattern. In the mc4r-coding sequence, in-frame insertions and deletions as well as nonsense and missense mutations have generated a high diversity of Mc4r-predicted proteins. Most of these variants are expressed in embryos, adults, and/or tumors. Functional receptor characterization demonstrated major divergence in pharmacological behavior for Mc4r receptors encoded by different copies of platyfish mc4r, with differences in constitutive activity as well as binding and stimulation by hormones. The high degree of allelic and copy-number variation observed between individuals can explain the high level of polymorphism for sexual maturation, fecundity, and body size in the platyfish: multiple combinations of Mc4r variants with different biochemical properties might interact to modulate the melanocortin signaling that regulates the hypothalamus-pituitary-gonadal axis. © 2013 by the Genetics Society of America.

Pradel N.,Aix - Marseille University | Ji B.,Aix - Marseille University | Gimenez G.,University of Monastir | Talla E.,Aix - Marseille University | And 11 more authors.
PLoS ONE | Year: 2013

Desulfovibrio piezophilus strain C1TLV30T is a piezophilic anaerobe that was isolated from wood falls in the Mediterranean deep-sea. D. piezophilus represents a unique model for studying the adaptation of sulfate-reducing bacteria to hydrostatic pressure. Here, we report the 3.6 Mbp genome sequence of this piezophilic bacterium. An analysis of the genome revealed the presence of seven genomic islands as well as gene clusters that are most likely linked to life at a high hydrostatic pressure. Comparative genomics and differential proteomics identified the transport of solutes and amino acids as well as amino acid metabolism as major cellular processes for the adaptation of this bacterium to hydrostatic pressure. In addition, the proteome profiles showed that the abundance of key enzymes that are involved in sulfate reduction was dependent on hydrostatic pressure. A comparative analysis of orthologs from the non-piezophilic marine bacterium D. salexigens and D. piezophilus identified aspartic acid, glutamic acid, lysine, asparagine, serine and tyrosine as the amino acids preferentially replaced by arginine, histidine, alanine and threonine in the piezophilic strain. This work reveals the adaptation strategies developed by a sulfate reducer to a deep-sea lifestyle. © 2013 Pradel et al.

PubMed | Institute Of Genomique Genoscope, Leibniz Institute DSMZ German Collection of Microorganisms and Cell Cultures, Paris-Sorbonne University, Max Planck Institute for Marine Microbiology and University of Bayreuth
Type: Journal Article | Journal: Environmental microbiology | Year: 2016

Marine Bacteroidetes have pronounced capabilities of degrading high molecular weight organic matter such as proteins and polysaccharides. Previously we reported on 76 Bacteroidetes-affiliated fosmids from the North Atlantic Oceans boreal polar and oligotrophic subtropical provinces. Here, we report on the analysis of further 174 fosmids from the same libraries. The combined, re-assembled dataset (226 contigs; 8.8 Mbp) suggests that planktonic Bacteroidetes at the oligotrophic southern station use more peptides and bacterial and animal polysaccharides, whereas Bacteroidetes at the polar station (East-Greenland Current) use more algal and plant polysaccharides. The latter agrees with higher abundances of algae and terrigenous organic matter, including plant material, at the polar station. Results were corroborated by in-depth bioinformatic analysis of 14 polysaccharide utilisation loci from both stations, suggesting laminarin-specificity for four and specificity for sulfated xylans for two loci. In addition, one locus from the polar station supported use of non-sulfated xylans and mannans, possibly of plant origin. While peptides likely represent a prime source of carbon for Bacteroidetes in open oceans, our data suggest that as yet unstudied clades of these Bacteroidetes have a surprisingly broad capacity for polysaccharide degradation. In particular, laminarin-specific PULs seem widespread and thus must be regarded as globally important.

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