title: Immunocytochemical and immunogold analyses of histone H4 acetylation during Chara vulgaris spermiogenesis.
abstract: Histone acetylation is one of the epigenetic modifications which play a significant role in chromatin remodeling during spermiogenesis. Acetylation of the histone H4 makes the exchange of nucleoproteins easy. Research on mouse spermatogenesis showed that H4 histone acetylated at Lys 12 (H4K12ac) was specific only to spermatids. Immunocytochemical studies of Chara vulgaris spermatids with the use of antibodies against the histone H4K12ac revealed positive reactions in spermatid nuclei at stages I-VII. This reaction, connected with nuclear condensation, was much stronger at the early stages of spermiogenesis than later on. Moreover, it showed that at the stages V-VII in spermatid nuclei the presence of the histone H4K12ac corresponded with DNA double-strand breaks. Electron microscopy studies with the use of immunogold technique revealed an almost twofold difference between the mean total numbers of gold grains in the examined chromatin in both stages. This study showed nearly equal distribution of gold grains on condensed and non-condensed chromatin of spermatids at the stage III/IV (48.11% and 51.89%, respectively). In the later stage-VI, when chromatin condensation proceeded, labeling of condensed chromatin reached 57.27%, while in the case of non-condensed chromatin it dropped to 42.73%. The percentage analysis also revealed an increase (above 9%) in condensed chromatin labeling in relation to the stage III/IV. Intensive acetylation of histone H4 at the early stages is correlated with DNA DSBs and transcriptional activity. It facilitates chromatin loosening, which enables the correct course of chromatin remodeling at a later stage. Histone γH2AX also influences chromatin structure in many biological processes in different cell types. Current studies reveal other similarities regarding histone H4 acetylation, not only between Chara and mammals but between invertebrates (molluscs) and vertebrates (bony fishes) as well.
authors.affiliation: Department of Cytophysiology, Faculty of Biology and Environmental Protection, University of Łódź, Pomorska 141/143, 90-236 Łódź, Poland. Electronic address: wojag@biol.uni.lodz.pl.
authors.forename: Agnieszka
authors.initials: A
authors.lastname: Wojtczak
mesh_terms: D000107:Acetylation; D002467:Cell Nucleus / Q000235:genetics / Q000378:metabolism* / Q000648:ultrastructure*; D044784:Chara / Q000378:metabolism / Q000502:physiology* / Q000648:ultrastructure*; D002843:Chromatin / Q000235:genetics / Q000648:ultrastructure*; D042002:Chromatin Assembly and Disassembly; D056130:Gametogenesis, Plant; D006570:Heterochromatin / Q000648:ultrastructure; D006657:Histones / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D007150:Immunohistochemistry; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism
chemical_list: D002843:Chromatin; D006570:Heterochromatin; D006657:Histones; D009687:Nuclear Proteins
keywords: Chara vulgaris; Chromatin remodeling; Histone H4; Histone acetylation; Immunogold technique; Nuclear protein exchange; Spermiogenesis