0000000000396936
AUTHOR
Eva Tarazona
Multilocus sequence analysis of putative Vibrio mediterranei strains and description of Vibrio thalassae sp. nov.
A multilocus sequence analysis based on partial gyrB, mreB, rpoD and pyrH genes was undertaken with 61 putative Vibrio mediterranei/V. shilonii strains from different hosts (mussels, oysters, clams, coral, fish and plankton) or habitat (seawater and sediment) and geographical origins (Mediterranean, Atlantic and Pacific). A consistent grouping was obtained with individual and concatenated gene sequences, and the clade, comprising 54 strains, was split into three subclades by all methods: subclade A (40 strains, including AK1, the former type strain of Vibrio shilonii), subclade B (8 strains) corresponding to the species V. mediterranei, and subclade C (six strains) representing a new specie…
An MLSA approach for the taxonomic update of the Splendidus clade, a lineage containing several fish and shellfish pathogenic Vibrio spp.
A multilocus sequence analysis was undertaken in order to redefine the Splendidus clade of the genus Vibrio, a large group of species containing several pathogenic members that affect fish and shellfish, and are difficult to identify through both phenotypic and genotypic approaches. The study included analysis of partial sequences of recA, gyrB, mreB, rpoD and pyrH genes, as well as the 16S rRNA gene. Seventeen type strain species were included that were complemented with other reference strains and a collection of isolates tentatively identified as members of this clade, as well as a set of other Vibrio species. The clade was well defined and stable in all analyses, and was confirmed to co…
Gene expression in diapausing rotifer eggs in response to divergent environmental predictability regimes
AbstractIn unpredictable environments in which reliable cues for predicting environmental variation are lacking, a diversifying bet-hedging strategy for diapause exit is expected to evolve, whereby only a portion of diapausing forms will resume development at the first occurrence of suitable conditions. This study focused on diapause termination in the rotifer Brachionus plicatilis s.s., addressing the transcriptional profile of diapausing eggs from environments differing in the level of predictability and the relationship of such profiles with hatching patterns. RNA-Seq analyses revealed significant differences in gene expression between diapausing eggs produced in the laboratory under com…
Vibrio renipiscarius sp. nov., isolated from cultured gilthead sea bream (Sparus aurata)
Two strains of Gram-negative, facultatively anaerobic, slightly halophilic bacteria, isolated from healthy gilthead sea bream (Sparus aurata) cultured in Spanish Mediterranean fish farms, were different from their closest relatives,Vibrio scophthalmiandV. ichthyoenteri, by phenotypic, phylogenetic and genomic standards. The strains were negative for decarboxylase tests and lacked extracellular hydrolytic activities, but were able to fermentd-mannitol, sucrose, cellobiose andd-gluconate, among other carbohydrates. The major cellular fatty acids were C16:1and C16:0, in agreement with other species of the genusVibrio. Their 16S rRNA gene sequences were 98.4 and 97.2 % similar to those of the t…
Multilocus Sequence Analysis of the redefined clade Scophthalmi in the genus Vibrio.
A Multilocus Sequence Analysis (MLSA) was performed on members of the Scophthalmi clade in the genus Vibrio, including type and reference strains of the species V. scophthalmi, V. ichthyoenteri, and 39 strains phenotypically identified as Vibrio ichthyoenteri-like, with the aim of better defining boundaries between these two closely related, fish-associated species. The type strain of V. ponticus, recently added to the clade Scophthalmi, was also included. The study was based on partial sequences of the protein-coding housekeeping genes rpoD, mreB, recA, ftsZ, and gyrB, and the 16S rRNA. While the 16S rRNA gene-based trees were unable to pull apart members of V. scophthalmi or V. ichthyoent…
Ecological genomics of adaptation to unpredictability in experimental rotifer populations
AbstractElucidating the genetic basis of phenotypic variation in response to different environments is key to understanding how populations evolve. Facultatively sexual rotifers can develop adaptive responses to fluctuating environments. In a previous evolution experiment, diapause-related traits changed rapidly in response to two selective regimes (predictable vs unpredictable) in laboratory populations of the rotifer Brachionus plicatilis. Here, we investigate the genomic basis of adaptation to environmental unpredictability in these experimental populations. We identified and genotyped genome-wide polymorphisms in 169 clones from both selective regimes after seven cycles of selection usi…