title: Coreactivation of four inactive X genes in a hamster x human hybrid and persistence of late replication of reactivated X chromosome.
abstract: Hamster-human hybrids which contained an inactive human X chromosome were treated by 5-azacytidine. Hypoxanthine guanine phosphoribosyltransferase derepressed hybrids were selected and derepression of three other loci, phosphoglycerate kinase, alpha-galactosidase, and glucose-6-phosphate dehydrogenase were studied. Among 32 hybrids selected for hypoxanthine guanine phosphoribosyltransferase, two were found to be reactivated at four X loci. The independence or nonindependence of the reactivation events will be discussed. No correlation was found between the time of replication and the expression or nonexpression of the X chromosome genes: X chromosomes reactivated at four loci remained late replicating; conversely early replication can exist without the expression of some X genes.
mesh_terms: D000818:Animals; D001374:Azacitidine / Q000633:toxicity; D006224:Cricetinae; D004261:DNA Replication; D004303:Dosage Compensation, Genetic; D005260:Female; D005796:Genes; D006801:Humans; D006822:Hybrid Cells / Q000648:ultrastructure*; D007041:Hypoxanthine Phosphoribosyltransferase / Q000235:genetics; D007621:Karyotyping; D008297:Male; D009154:Mutation; D014960:X Chromosome
chemical_list: D007041:Hypoxanthine Phosphoribosyltransferase; D001374:Azacitidine