[Mutagenic effect of combined exposure to 8-methoxypsoralen or angelicin and long-wave ultraviolet light in uvs-strains of Aspergillus nidulans].

Combined mutagenic effect of near ultraviolet irradiation (NUV, lambda > 320 nm) and angelicin, which forms monoadducts, or 8-methoxypsoralen (8-MOP), which forms monoadducts and cross-links in DNA, were studied in uvs and uvs+ strains of Aspergillus nidulans. Mutations were induced intensively by both kinds of furocumarins. The induction of mutations by angelicin testifies the significance of psoralen-pyrimidine monoadducts in mutagenesis. Using the method of fractionating NUV-irradiation and studying the influence of monoadducts repair to the mutation frequency, it is found the interstrand crosslinks of DNA induced by 8-MOP plus NUV are also nighly mutagenic. The products of genes uvs 12, uvs 20b and uvs 26, acting in DNA excision repair, do not participate in forming the mutations induced by furocumarins plus NUV in Aspergillus nidulans. The products of genes uvs 19, uvs 20a, participating in DNA post-replicative repair, are important for repair of premutational damages induced by furocumarins plus NUV.