title: Specific silver staining of experimentally undercondensed chromosome regions.
abstract: Treatment of human and mouse cell cultures with DNA binding AT-specific compounds and with some base analogues induced distinct undercondensations in several heterochromatic chromosome regions. All those heterochromatic regions undercondensed by AT-specific DNA ligands (distamycin A, DAPI, Hoechst 33258) could be heavily labeled with the silver(Ag)-staining technique; but the heterochromatic regions undercondensed with the cytidine analogue 5-azacytidine were Ag-negative. In metaphase chromosomes from BrdU-treated human cell cultures, the bifilarly substituted chromatids, which show a slight undercondensation, were also Ag-negative. Cytochemical analyses of the Ag-stained undercondensed heterochromatic regions showed that the Ag-stainable material consisted of nonhistone proteins. The mechanism of Ag staining in the undercondensed heterochromatic regions was compared with Ag staining of the nucleolus organizer regions.
mesh_terms: D000818:Animals; D001374:Azacitidine / Q000494:pharmacology; D001854:Bone Marrow Cells; D001973:Bromodeoxyuridine / Q000494:pharmacology; D002478:Cells, Cultured; D002875:Chromosomes / Q000648:ultrastructure*; D002877:Chromosomes, Human / Q000648:ultrastructure*; D004247:DNA / Q000032:analysis*; D004214:Distamycins / Q000494:pharmacology; D005347:Fibroblasts / Q000166:cytology; D006570:Heterochromatin / Q000187:drug effects / Q000648:ultrastructure; D006801:Humans; D007621:Karyotyping; D008214:Lymphocytes / Q000166:cytology; D051379:Mice; D012834:Silver; D013194:Staining and Labeling
chemical_list: D004214:Distamycins; D006570:Heterochromatin; D012834:Silver; C030000:stallimycin; D004247:DNA; D001973:Bromodeoxyuridine; D001374:Azacitidine