title: Allocyclic X chromosome visualized by drug-induced premature chromosome condensation.
abstract: Calyculin A, an inhibitor of serine/threonine protein phosphatases, can induce premature chromosome condensation (PCC) in human peripheral lymphocytes. In female lymphocytes treated with calyculin, one highly condensed chromosome per nucleus was frequently observed at early to middle S phase. When these PCC spreads were hybridized with a whole chromosome-painting probe for the X chromosome, one large spot and a cluster of small spots were observed in a cell. Judging from the Giemsa stained image, the former seemed to have finished DNA replication, while the latter was in the process of replication. Because this large spot was seldom observed in male PCC spreads, it was considered an inactive X chromosome. The inconsistency of this observation with earlier reports that the inactive X chromosome replicates later than autosomes and the active homolog is discussed.
authors.affiliation: Division of Radiobiology and Biodosimetry, National Institute of Radiological Sciences, 4-9-1, Anagawa, Inage-ku, Chiba 263-8555, Japan.
authors.forename: R
authors.initials: R
authors.lastname: Kanda
authors.forename: I
authors.initials: I
authors.lastname: Hayata
mesh_terms: D020223:Chromosome Painting; D004303:Dosage Compensation, Genetic; D005260:Female; D006801:Humans; D008214:Lymphocytes / Q000648:ultrastructure; D008387:Marine Toxins; D010080:Oxazoles / Q000494:pharmacology; D010749:Phosphoprotein Phosphatases / Q000037:antagonists & inhibitors; D013194:Staining and Labeling; D014960:X Chromosome / Q000648:ultrastructure*
chemical_list: D008387:Marine Toxins; D010080:Oxazoles; C059041:calyculin A; D010749:Phosphoprotein Phosphatases