title: The induction of mutations to 2-thioxanthine resistance in inhibitor depleted conidia of Aspergillus nidulans by gamma-radiation in the presence of oxygen or nitrogen.
abstract: A strain of Aspergillus nidulans has been used to study the inactivating and mutagenic effect of 60Cogamma-rays in the presence of oxygen or nitrogen. Mutation was studied by the 2-thioxanthine system which selectively detects forward mutation at a number of gene loci (at least 16). Mutants resistant to conidial pigmentation effects of 2-thioxanthine can be divided into four main classes (2TxR, hx, uaY and cnx) and three of these classes (hx, uaY and cnx) can be further characterized at the gene level. The results demonstrate the existence of a marked differential forward mutational response of gene loci in Aspergillus conidia which is dependent upon whether gamma-irradiation in aqueous suspension was carried out in the presence of oxygen or of nitrogen: this effect is independent of the dose of radiation exposure. The specificity for mutation is altered by the presence of the self-inhibitor of germination for the anoxic treatment but not the oxic irradiation. The implication of different oer's (oxygen enhancement ratios) for mutation induction in different classes or genes for the mechanism and type of damage induced by the two radiation conditions are discussed.
mesh_terms: D001233:Aspergillus nidulans / Q000187:drug effects / Q000528:radiation effects*; D004352:Drug Resistance, Microbial; D005720:Gamma Rays; D005796:Genes; D009584:Nitrogen; D010100:Oxygen; D013892:Thioxanthenes / Q000494:pharmacology
chemical_list: D013892:Thioxanthenes; D009584:Nitrogen; D010100:Oxygen