title: Effect of caffeine on G2 repair and its reversion by adenosine.
abstract: Chromosome damage induced in root meristems of Allium cepa L. by an 18-h treatment with 5-aminouracil (AU) was enhanced by 2-h pulses with 5 mM caffeine, the most effective pulse being given from the 8th to the 10th h after AU. Chromosome damage was detected by the percentage of anaphases or telophases showing chromosomal aberrations. This caffeine effect was partially reversed by adenosine. We suggest that this caffeine anti-repair effect could be due to a competition between methylxanthine and an adenine-nucleotide derivative (ATP?) required for some step(s) of G2-prophase repair.
mesh_terms: D000241:Adenosine / Q000494:pharmacology*; D000255:Adenosine Triphosphate / Q000502:physiology; D002110:Caffeine / Q000494:pharmacology*; D002453:Cell Cycle / Q000187:drug effects; D002869:Chromosome Aberrations; D002875:Chromosomes / Q000187:drug effects*; D004260:DNA Repair / Q000187:drug effects*; D010944:Plants; D011838:Radiation-Sensitizing Agents; D014498:Uracil / Q000031:analogs & derivatives / Q000494:pharmacology; D014970:Xanthines / Q000502:physiology
chemical_list: D011838:Radiation-Sensitizing Agents; D014970:Xanthines; C008514:methylxanthine; D002110:Caffeine; D014498:Uracil; D000255:Adenosine Triphosphate; D000241:Adenosine; C011166:5-aminouracil