Identical sets of methylated and nonmethylated genes in Ciona intestinalis sperm and muscle cells

BACKGROUND: The discovery of gene body methylation, which refers to DNA methylation within gene coding region, suggests an as yet unknown role of DNA methylation at actively transcribed genes. In invertebrates, gene bodies are the primary targets of DNA methylation, and only a subset of expressed genes is modified. RESULTS: Here we investigate the tissue variability of both the global levels and distribution of 5-methylcytosine (5mC) in the sea squirt Ciona intestinalis. We find that global 5mC content of early developmental embryos is high, but is strikingly reduced in body wall tissues. We chose sperm and adult muscle cells, with high and reduced levels of global 5mC respectively, for genome-wide analysis of 5mC targets. By means of CXXC-affinity purification followed by deep sequencing (CAP-seq), and genome-wide bisulfite sequencing (BS-seq), we designated body-methylated and unmethylated genes in each tissue. Surprisingly, body-methylated and unmethylated gene groups are identical in the sperm and muscle cells. Our analysis of microarray expression data shows that gene body methylation is associated with broad expression throughout development. Moreover, transgenic analysis reveals contrasting gene body methylation at an identical gene-promoter combination when integrated at different genomic sites. CONCLUSIONS: We conclude that gene body methylation is not a direct regulator of tissue specific gene expression in C. intestinalis. Our findings reveal constant targeting of gene body methylation irrespective of cell type, and they emphasize a correlation between gene body methylation and ubiquitously expressed genes. Our transgenic experiments suggest that the promoter does not determine the methylation status of the associated gene body

Roles of Charged Residues in the C-Terminal Region of PomA, a Stator Component of the Na+-Driven Flagellar Motor▿

Bacterial flagellar motors use specific ion gradients to drive their rotation. It has been suggested that the electrostatic interactions between charged residues of the stator and rotor proteins are important for rotation in Escherichia coli. Mutational studies have indicated that the Na+-driven motor of Vibrio alginolyticus may incorporate interactions similar to those of the E. coli motor, but the other electrostatic interactions between the rotor and stator proteins may occur in the Na+-driven motor. Thus, we investigated the C-terminal charged residues of the stator protein, PomA, in the Na+-driven motor. Three of eight charge-reversing mutations, PomA(K203E), PomA(R215E), and PomA(D220K), did not confer motility either with the motor of V. alginolyticus or with the Na+-driven chimeric motor of E. coli. Overproduction of the R215E and D220K mutant proteins but not overproduction of the K203E mutant protein impaired the motility of wild-type V. alginolyticus. The R207E mutant conferred motility with the motor of V. alginolyticus but not with the chimeric motor of E. coli. The motility with the E211K and R232E mutants was similar to that with wild-type PomA in V. alginolyticus but was greatly reduced in E. coli. Suppressor analysis suggested that R215 may participate in PomA-PomA interactions or PomA intramolecular interactions to form the stator complex

Identical sets of methylated and nonmethylated genes in Ciona intestinalis sperm and muscle cells

Abstract Background The discovery of gene body methylation, which refers to DNA methylation within gene coding region, suggests an as yet unknown role of DNA methylation at actively transcribed genes. In invertebrates, gene bodies are the primary targets of DNA methylation, and only a subset of expressed genes is modified. Results Here we investigate the tissue variability of both the global levels and distribution of 5-methylcytosine (5mC) in the sea squirt Ciona intestinalis. We find that global 5mC content of early developmental embryos is high, but is strikingly reduced in body wall tissues. We chose sperm and adult muscle cells, with high and reduced levels of global 5mC respectively, for genome-wide analysis of 5mC targets. By means of CXXC-affinity purification followed by deep sequencing (CAP-seq), and genome-wide bisulfite sequencing (BS-seq), we designated body-methylated and unmethylated genes in each tissue. Surprisingly, body-methylated and unmethylated gene groups are identical in the sperm and muscle cells. Our analysis of microarray expression data shows that gene body methylation is associated with broad expression throughout development. Moreover, transgenic analysis reveals contrasting gene body methylation at an identical gene-promoter combination when integrated at different genomic sites. Conclusions We conclude that gene body methylation is not a direct regulator of tissue specific gene expression in C. intestinalis. Our findings reveal constant targeting of gene body methylation irrespective of cell type, and they emphasize a correlation between gene body methylation and ubiquitously expressed genes. Our transgenic experiments suggest that the promoter does not determine the methylation status of the associated gene body

胆嚢壁内側低エコー層肥厚と胆嚢腺筋腫症に着目した腹部超音波検査による膵胆管合流異常の早期発見

雑誌掲載版合流異常合併胆嚢43例(非拡張型19例、拡張型24例)の超音波(US)所見と切除胆嚢の病理組織学的所見を比較し、合流異常の早期診断におけるUSの有用性について検討した。その結果、全体では胆嚢壁肥厚を60%、胆嚢壁内側低エコー層肥厚あるいは胆嚢腺筋腫症のいずれかを82.9%に認めた。また、非拡張型では4mm以上の胆嚢壁肥厚を88.2%、更に胆嚢壁内側肥厚と胆嚢腺筋腫症の両方、あるいはいずれかを94.1%に認めたのに対し、拡張型ではそれぞれ33.3%、66.7%であった。以上より、検診の腹部USで壁肥厚や内側低エコー層肥厚、胆嚢腺筋腫症を認めた場合には、合流異常の存在を疑うことが本症の早期発見につながると考えられた。尚、USを契機に発見された合流異常の検討から、検診対象者のうち腹部症状の現病歴・既往歴のある者や女性に対しては、胆嚢壁の所見に深く注意を払いながらUSを行う必要があると示唆された