A polyamine-sensitive mutant of Aspergillus nidulans.

A mutation designated spsA1 has been induced in the putrescine (puA2) auxotroph of Aspergillus nidulans which enables this mutant to grow on low concentrations of spermidine in place of putrescine. In addition, the spsA1 mutant, irrespective of putrescine requirement, is abnormally sensitive to high concentrations of spermidine, spermine or the polyamine analogue methylglyoxal bis(guanylhydrazone). When spsA1 strains are grown on medium containing spermidine, uptake of the polyamine continues at a high level for a longer period than in the wild-type and leads to a doubled intracellular spermidine pool. A similar increase in the intracellular spermine pool results from growth on spermine.