title: DNA methylation and histone modification in onion chromosomes.
abstract: Onion, Allium cepa, is a model plant for experimental observation of somatic cell division, whose mitotic chromosome is extremely large, and contains the characteristic terminal heterochromatin. Epigenetic status of the onion chromosome is a matter of deep interest from a molecular cytogenetic point of view, because epigenetic marks regulate chromatin structure and gene expression. Here we examined chromosomal distribution of DNA methylation and histone modification in A. cepa in order to reveal the chromatin structure in detail. Immunodetection of 5-methylcytosine (5mC) and in situ nick-translation analysis showed that onion genomic DNA was highly methylated, and the methylated CG dinucleotides were distributed in entire chromosomes. In addition, distributions of histone methylation codes, which occur in close association with DNA methylation, were similar to those of other large genome species. From these results, a highly heterochromatic and less euchromatic state of large onion chromosomes were demonstrated at an epigenetic level.
authors.affiliation: Division of Natural Science, Osaka Kyoiku University, Kashiwara, Osaka, Japan.
authors.forename: Go
authors.initials: G
authors.lastname: Suzuki
authors.forename: Maho
authors.initials: M
authors.lastname: Shiomi
authors.forename: Sayuri
authors.initials: S
authors.lastname: Morihana
authors.forename: Maki
authors.initials: M
authors.lastname: Yamamoto
authors.forename: Yasuhiko
authors.initials: Y
authors.lastname: Mukai
mesh_terms: D044503:5-Methylcytosine / Q000737:chemistry; D002875:Chromosomes / Q000235:genetics; D032461:Chromosomes, Plant / Q000235:genetics; D019175:DNA Methylation / Q000235:genetics*; D057890:Epigenomics; D022041:Euchromatin / Q000235:genetics; D016678:Genome; D006570:Heterochromatin / Q000737:chemistry / Q000235:genetics; D006657:Histones / Q000737:chemistry / Q000235:genetics*; D017404:In Situ Hybridization, Fluorescence; D019697:Onions / Q000235:genetics* / Q000378:metabolism; D011499:Protein Processing, Post-Translational / Q000235:genetics
chemical_list: D022041:Euchromatin; D006570:Heterochromatin; D006657:Histones; D044503:5-Methylcytosine