Photoreactivation of ultraviolet-induced chromosomal aberrations.

Ultraviolet induces only chromatid-type aberrations in synchronized G(1) V-79 Chinese hamster and A8W243 Xenopus tissue culture cells. Posttreatment with white light prevents expression of most potential aberrations in the A8 toad cell, which possesses a photoreactivation enzyme. We conclude that the major ultraviolet-induced DNA lesion leading to chromosomal aberrations is the pyrimidine dimer.