Abstract
Anucleate primary sterigmata (aps) mutants of Aspergillus nidulans are partially blocked in conidiation (asexual sporulation) due to failure of the organized migration of nuclei into the conidiophore metulae. The mutants also have a slightly reduced hyphal growth rate and irregular distribution of nuclei in vegetative hyphae; the hyphal phenotype appears somewhat more variable than the conidiation defect. The mutants fall into two complementation groups, apsA and apsB, mapping on chromosomes IV and VI, respectively. apsB mutants are also partially defective in sexual reproduction.