Genetic analysis of the phosphatases in Aspergillus nidulans

Abstract

Summary1. A histochemical method has been applied to the detection of alkaline and acid phosphatase mutants in single colonies of Aspergillus nidulans.2. With the above method it has been possible to isolate mutants in which the alkaline and acid phosphatase activities are affected either separately or simultaneously.3. Crude extracts of wild-type A. nidulans contain four electrophoretically distinct phosphatase components, two with activity at alkaline pH and two with activity at acid pH. Genes affecting three of the four components have been identified.4. Two suppressor mutants of an alkaline phosphataseless mutant (palB7) have been isolated. In a strain carrying palB7 and one of these suppressors, the restoration of an alkaline phosphatase component is accompanied by loss of the faster acid phosphatase component. In a similar strain carrying the other suppressor, the partial restoration of the alkaline phosphatase component goes with an electrophoretic alteration of the slower acid phosphatase component.5. Genetic analysis of twenty-seven mutants has resulted in the identification of fifteen loci affecting the phosphatases. All these loci have been assigned to linkage groups, and twelve of them were also mapped meiotically in relation to other loci.6. One possible model (based on heteropolymeric proteins) has been proposed to account for the electrophoretic and genetic data on the various phosphatase and suppressor mutations.