No abstract

In the cellular slime mold Dictyostelium discoideum, Countin and Countin2 proteins are thought to control the size of the multicellular structure since the countinstrain forms a huge fruiting body and countin2strain forms a small fruiting body. Recently, the countin3 gene encoding a polypeptide homologous to Countin and Countin2 was identified in the D. discoideum genome. The countin3strain formed a 1.8-fold larger number of aggregates, resulting in smaller fruiting bodies compared to those formed by the wild-type. The extent of cell-cell adhesion was reduced in the mutant, indicating that Countin3 protein regulates size by controlling the amounts of proteins responsible for the adhesion.

The cellular slime mold Dictyostelium discoideum expresses three genes (sodA, sodB and sodC) encoding the extracellular Cu/Zn superoxide dismutases. Following H 2 O 2 treatment, the expression of sodA and sodB increased while that of sodC decreased. The sodC null strain formed multinucleate cells in a shaking culture. These results suggest that sodC plays a unique role in Dictyostelium discoideum.

No abstract

No abstract