title: The action of ultraviolet light on the patterns of banding induced by restriction endonucleases in human chromosomes.
abstract: The irradiation of metaphase spreads of human cells with ultraviolet (UV) light blocked the chromosome banding induced by Alu I, Mbo I, Dde I, Hinf I, Hae III, and Rsa I restriction endonucleases. At 13 J/m2 there was moderate inhibition of the nuclease action, which was detected as an increase in the stain intensity of chromosomes (Alu I, Mbo I, Dde I, Rsa I) or as a change in the banding pattern (Hinf I, Hae III). AT 70-300 J/m2 the UV-induced blockage was complete; the chromosomes showed no banding, and stain intensity was similar to that of control slides incubated with buffer. BrdU substitution and the irradiation of BrdU-substituted chromosomes with 313 nm light at 1800-15000 J/m2 did not block the action of restriction nucleases. On the other hand, UV irradiation of BrdU-substituted chromosomes inhibited the action of restriction enzymes at the same fluences that blocked the nuclease action in unsubstituted chromosomes. The data indicate that DNA-protein crosslinkage is the factor inhibiting DNA extraction and chromosome banding.
mesh_terms: D002478:Cells, Cultured; D002871:Chromosome Banding; D002877:Chromosomes, Human / Q000187:drug effects / Q000528:radiation effects*; D004262:DNA Restriction Enzymes / Q000494:pharmacology*; D005260:Female; D006801:Humans; D007621:Karyotyping; D008214:Lymphocytes / Q000166:cytology / Q000187:drug effects / Q000528:radiation effects; D008297:Male; D014466:Ultraviolet Rays
chemical_list: D004262:DNA Restriction Enzymes