The Genetics of Aspergillus nidulans

This discusses the lifecycle, the methods of culture, the isolation of mutants, the formal genetics, the identification of loci, and the diploids and mitotic recombination of Aspergillus nidulans (A. nidulans). It also presents various methods of genetic analysis, such as heterokaryosis, crossing, recombinant selection from random samples of ascosporesa, and perithecium analysis and relative heterothallism. As in most other filamentous fungi in which sexual reproduction occurs, A. nidulans (Eidam) Winter, an ascomycete shows a vegetative cycle side-by-side with a sexual cycle. On germination, an uninucleate haploid vegetative spore (conidium) produces colorless septate hyphae with multinucleate cells. The sexual cycle is concentrated in specialized organs, the fruiting bodies (cleistothecia or perithecia). The biochemical genetics of A. nidulans, though similar to that of Neurospora and Ophiostoma, has revealed interesting differences in detail: e.g., the inability of citrulline to replace ornithine for strains responding to ornithine or arginine; the inability of tryptophan to replace anthranilic acid for certain strains responding to anthranilic acid or nicotinic acid; the competitive inhibition by lysine of exogenous arginine or ornithine, and its sparing effect on exogenous proline; etc.