Mitotic mutants of<i>Aspergillus nidulans</i>

Abstract

SUMMARY Forty-five temperature-sensitive mutants of Aspergillus nidulans which are defective in nuclear division, septation or distribution of nuclei along the mycelium have been isolated, and most have been subjected to complementation analysis and mapped to chromosome. Thirty-five of the mutants were unable to complete nuclear division at the restrictive temperature. Twenty-six of these mutants exhibited a co-ordinate drop in both spindle and chromosome mitotic indices at 42 °C, indicating that they fail to enter mitosis. These mutants have been assigned to the gene symbol nim . Nine mutants exhibited a co-ordinate rise in spindle and chromosome mitotic indices at 42 °C, indicating that they are arrested in mitosis. These mutants were assigned the gene symbol bim . Five mutants failed to form septa and were given the gene symbol sep ; and five mutants had an abnormal nuclear distribution and were given the gene symbol nud . All of the mutations were recessive. Most of the mutants were in different complementation groups. Mutants in the same complementation groups were phenotypically similar, but phenotypically similar mutants were not necessarily or usually in the same complementation group. There was no evidence for genetic clustering of phenotypically similar mutants. The mutants were located on all eight chromosomes.