Excision of ultraviolet and gamma ray products of the 5,6-dihydroxy-dihydrothymine type by nuclear preperations of xeroderma pigmentosum cells.

Monomeric products of the 5,6-dihydroxy-dihydrothymine type are produced in the DNA by both ultraviolet and ionizing radiations. The capacity of nuclear preparations from normal and Xeroderma pigmentosum (XP) cells (Complementation groups A, B, C and D) to excise such products from ultraviolet or gamma-irradiated T7DNA was comparable and was independent of radiation induced strand breaks.