title: Analysis of deoxyribonucleic acid replication in human X chromosomes by fluorescence microscopy.
abstract: The genetically inactive, late-replicating human female X chromosome can be effectively distinguished from its more active, earlier-replicating homologue, when cells are grown according to the appropriate BrdU-33258 Hoechst protocol. Results obtained from a fluorescence analysis of DNA replication in X chromosomes are consistent with those from previous autoradiographic studies, but reflect additional sensitivity and resolution offered by the BrdU-Hoechst methodology. Both qualitative and quantitative differences in 33258 Hoechst fluorescence intensity, reflecting alterations in replication kinetics, can be detected between the two X chromosomes in female cells. The pattern of replication in the single X chromosome in male cells is indistinguishable from that of the early female X. Intercellular fluctuations in the distribution of regions replicating early or late in S phase, particularly with reference to the late female X, can be localized to structural bands, suggesting multifocal control of DNA synthesis in X chromosomes.
mesh_terms: D001345:Autoradiography; D001973:Bromodeoxyuridine / Q000494:pharmacology; D004261:DNA Replication; D005260:Female; D005456:Fluorescent Dyes; D006801:Humans; D008297:Male; D008856:Microscopy, Fluorescence; D012730:Sex Chromosomes / Q000187:drug effects / Q000378:metabolism*
chemical_list: D005456:Fluorescent Dyes; D001973:Bromodeoxyuridine