title: Specific induction of uncoiling in NORs of human acrocentric chromosomes by 5-azacytidine and 5-azadeoxicytidine.
abstract: The organization of rDNA-containing chromatin was analysed by transmission electron microscopy after treatment of cultured human lymphocytes with 5-azacytidine (ACR) or 5-azadeoxicytidine (AdCR). The number of observed acrocentric chromosomes with satellites was significantly increased after treatment with low doses of ACR or AdCR during the last 24 h of culture, whereas with exposures during the last 7 h the number remained normal. The results suggest that the incorporation of ACR and AdCR in the early period of the S-phase may have reverted the non-satellized to satellized chromosomes. The cytidine analogues may have become more visible during secondary constriction thus changing the NOR structure leading to an increased number of satellized chromosomes.
authors.affiliation: Laboratório de Citogenética, Universidade do Porto, Portugal.
authors.forename: I
authors.initials: I
authors.lastname: Malheiro
authors.forename: B
authors.initials: B
authors.lastname: Porto
authors.forename: T
authors.initials: T
authors.lastname: Mello-Sampayo
authors.forename: V
authors.initials: V
authors.lastname: Goyanes
mesh_terms: D000328:Adult; D000964:Antimetabolites, Antineoplastic / Q000494:pharmacology*; D000970:Antineoplastic Agents / Q000494:pharmacology*; D001374:Azacitidine / Q000031:analogs & derivatives* / Q000494:pharmacology*; D002478:Cells, Cultured / Q000502:physiology / Q000648:ultrastructure; D002875:Chromosomes / Q000187:drug effects* / Q000235:genetics / Q000648:ultrastructure; D004276:DNA, Satellite / Q000032:analysis / Q000187:drug effects; D000077209:Decitabine; D005260:Female; D006801:Humans; D008214:Lymphocytes / Q000502:physiology / Q000648:ultrastructure; D008854:Microscopy, Electron; D009697:Nucleolus Organizer Region / Q000187:drug effects* / Q000235:genetics / Q000648:ultrastructure
chemical_list: D000964:Antimetabolites, Antineoplastic; D000970:Antineoplastic Agents; D004276:DNA, Satellite; D000077209:Decitabine; D001374:Azacitidine