Dataset Information

Draft Genome Sequences of Six Flavobacterium psychrophilum Strains Isolated from Dead Juvenile Ayu (Plecoglossus altivelis altivelis) near the Mouth of the Nahari River, Kochi, Japan.

ABSTRACT: Flavobacterium psychrophilum causes bacterial cold-water disease in ayu inhabiting clear rivers in Japan. In this study, we report the draft genome sequences of six F. psychrophilum strains isolated from the gills and skin of dead juvenile ayu near the mouth of the Nahari River.

SUBMITTER: Yamashita H

PROVIDER: S-EPMC6639631 | biostudies-literature | 2019 Jul

REPOSITORIES: biostudies-literature

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Draft Genome Sequences of Six Flavobacterium psychrophilum Strains Isolated from Dead Juvenile Ayu (Plecoglossus altivelis altivelis) near the Mouth of the Nahari River, Kochi, Japan.

Yamashita Hazuki H Wada Takayuki T Kato Yusuke Y Ikeda Takuji T Imajoh Masayuki M

Microbiology resource announcements 20190718 29

<i>Flavobacterium psychrophilum</i> causes bacterial cold-water disease in ayu inhabiting clear rivers in Japan. In this study, we report the draft genome sequences of six <i>F. psychrophilum</i> strains isolated from the gills and skin of dead juvenile ayu near the mouth of the Nahari River. ...[more]

PMID: 31320441

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Project description:Whole-genome duplication and genome compaction are thought to have played important roles in teleost fish evolution. Ayu (or sweetfish), Plecoglossus altivelis, belongs to the superorder Stomiati, order Osmeriformes. Stomiati is phylogenetically classified as sister taxa of Neoteleostei. Thus, ayu holds an important position in the fish tree of life. Although ayu is economically important for the food industry and recreational fishing in Japan, few genomic resources are available for this species. To address this problem, we produced a draft genome sequence of ayu by whole-genome shotgun sequencing and constructed linkage maps using a genotyping-by-sequencing approach. Syntenic analyses of ayu and other teleost fish provided information about chromosomal rearrangements during the divergence of Stomiati, Protacanthopterygii and Neoteleostei. The size of the ayu genome indicates that genome compaction occurred after the divergence of the family Osmeridae. Ayu has an XX/XY sex-determination system for which we identified sex-associated loci by a genome-wide association study by genotyping-by-sequencing and whole-genome resequencing using wild populations. Genome-wide association mapping using wild ayu populations revealed three sex-linked scaffolds (total, 2.03 Mb). Comparison of whole-genome resequencing mapping coverage between males and females identified male-specific regions in sex-linked scaffolds. A duplicate copy of the anti-Müllerian hormone type-II receptor gene (amhr2bY) was found within these male-specific regions, distinct from the autosomal copy of amhr2. Expression of the Y-linked amhr2 gene was male-specific in sox9b-positive somatic cells surrounding germ cells in undifferentiated gonads, whereas autosomal amhr2 transcripts were detected in somatic cells in sexually undifferentiated gonads of both genetic males and females. Loss-of-function mutation for amhr2bY induced male to female sex reversal. Taken together with the known role of Amh and Amhr2 in sex differentiation, these results indicate that the paralog of amhr2 on the ayu Y chromosome determines genetic sex, and the male-specific amh-amhr2 pathway is critical for testicular differentiation in ayu.

Project description:Bacteria of the family Flavobacteriaceae (flavobacteria) primarily comprise nonpathogenic bacteria that inhabit soil and water (both marine and freshwater). However, some bacterial species in the family, including Flavobacterium psychrophilum and Flavobacterium columnare, are known to be pathogenic to fish. Flavobacteria, including the abovementioned pathogenic bacteria, belong to the phylum Bacteroidota and possess two phylum-specific features, gliding motility and a protein secretion system, which are energized by a common motor complex. Herein, we focused on Flavobacterium collinsii (GiFuPREF103) isolated from a diseased fish (Plecoglossus altivelis). Genomic analysis of F. collinsii GiFuPREF103 revealed the presence of a type IX secretion system and additional genes associated with gliding motility and spreading. Using transposon mutagenesis, we isolated two mutants with altered colony morphology and colony spreading ability; these mutants had transposon insertions in pep25 and lbp26. The glycosylation material profiles revealed that these mutants lacked the high-molecular-weight glycosylated materials present in the wild-type strain. In addition, the wild-type strains exhibited fast cell population movement at the edge of the spreading colony, whereas reduced cell population behavior was observed in the pep25- and lbp26-mutant strains. In the aqueous environment, the surface layers of these mutant strains were more hydrophobic, and they formed biofilms with enhanced microcolony growth compared to those with the wild-type. In Flavobacterium johnsoniae, the Fjoh_0352 and Fjoh_0353 mutant strains were generated, which were based on the ortholog genes of pep25 and lbp26. In these F. johnsoniae mutants, as in F. collinsii GiFuPREF103, colonies with diminished spreading capacity were formed. Furthermore, cell population migration was observed at the edge of the colony in wild-type F. johnsoniae, whereas individual cells, and not cell populations, migrated in these mutant strains. The findings of the present study indicate that pep25 and lbp26 contribute to the colony spreading of F. collinsii.

Dataset Information

Draft Genome Sequences of Six Flavobacterium psychrophilum Strains Isolated from Dead Juvenile Ayu (Plecoglossus altivelis altivelis) near the Mouth of the Nahari River, Kochi, Japan.

Publications

Draft Genome Sequences of Six Flavobacterium psychrophilum Strains Isolated from Dead Juvenile Ayu (Plecoglossus altivelis altivelis) near the Mouth of the Nahari River, Kochi, Japan.

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