title: Effects of nucleotides on expression of the folate sensitive fragile sites.
abstract: Further studies on the effect of nucleotides upon expression of the folate sensitive fragile sites have confirmed that high concentrations of thymidine (300 mg/l) but not BrdU (600 mg/l) induce these fragile sites. Induction by thymidine can be suppressed by addition of cytidine in a dose response manner. Studies on other nucleotides suggest that guanosine, but not adenosine or cytidine, can induce the fragile sites. The previously hypothesised model for the DNA at a fragile site as a naturally occurring polypurine/polypyrimidine sequence which becomes amplified is further developed.
mesh_terms: D000241:Adenosine / Q000494:pharmacology; D001483:Base Sequence; D043283:Chromosome Fragile Sites; D002873:Chromosome Fragility; D003470:Culture Media; D003582:Cytogenetics; D003596:Cytosine / Q000494:pharmacology; D004247:DNA / Q000235:genetics; D005260:Female; D005492:Folic Acid / Q000494:pharmacology*; D005600:Fragile X Syndrome / Q000235:genetics; D006151:Guanosine / Q000494:pharmacology; D006801:Humans; D066298:In Vitro Techniques; D008297:Male; D009711:Nucleotides / Q000494:pharmacology*; D013936:Thymidine / Q000494:pharmacology
chemical_list: D003470:Culture Media; D009711:Nucleotides; D006151:Guanosine; D003596:Cytosine; D004247:DNA; D005492:Folic Acid; D000241:Adenosine; D013936:Thymidine