title: Fragile X chromosome and chromosome condensation.
abstract: The effect of chromosome condensation on the frequency of expression of the fragile X chromosome was examined. Chromosome decondensation substances were tested for their ability to elicit expression or improve frequencies of expression of the fragile X chromosome in five patients. The substances tested included the AT specific DNA ligands ethidium bromide, Hoechst 33258, and netropsin, and the GC specific substances actinomycin D and olivomycin. Under culture conditions appropriate for eliciting fragile X expression none of the decondensation compounds studied significantly altered frequencies of expression, nor did any of the substances elicit fragile X expression under conditions that normally suppress fragile X expression. The fragile X was found to be more frequently evident in less condensed chromosome preparations from fibroblasts. The implications of these findings with respect to the nature of fragile sites are discussed.
mesh_terms: D000368:Aged; D006690:Bisbenzimidazole / Q000494:pharmacology; D043283:Chromosome Fragile Sites; D002873:Chromosome Fragility; D003609:Dactinomycin / Q000494:pharmacology; D004996:Ethidium / Q000235:genetics; D005260:Female; D006801:Humans; D008214:Lymphocytes / Q000187:drug effects; D008297:Male; D009429:Netropsin / Q000235:genetics; D009848:Olivomycins / Q000494:pharmacology; D014960:X Chromosome / Q000187:drug effects
chemical_list: D003609:Dactinomycin; D009848:Olivomycins; D009429:Netropsin; D004996:Ethidium; D006690:Bisbenzimidazole