Evidence against mutational "hot-spots" at aggregation loci in Dictyostelium discoideum.

Complementation tests were performed on 10 strains of Dictyostelium discoideum which carry developmental mutations representing aggregation loci identified previously in two independent studies. When the 5 aggregation-deficient strains representing loci CGI-5 were fused with the 5 strains carrying mutations at loci ago A-E, all 25 crosses produced aggregation-competent diploids. Complicating factors, such as negative gene interactions and possible interallelic complementation are discussed. The results of this experiment suggest that the 10 aggregation loci identified in the two studies are different and that aggregation loci in D. discoideum are probably not associated with significant mutational "hot-spots".