Protein Synthesis Initiated by Cell Fusion in Dictyostelium discoideum

D. discoideum has two alternative developmental pathways. If cells of two complement mating-type strains, NC4 and HM1, fuse sexually, a giant cell is produced which subsequently develops into a macrocyst, the sexual structure of this organism. However, if fusion fails to occur and cells are starved, a fruiting-body is produced instead of a macrocyst. In this paper, a two-dimensional polypeptide gel electrophoresis study showed that giant cells produce specific polypeptides which may possibly be involved in macrocyst development. Out of total 497 polypeptides which appeared in a giant cell during an incubation period of 13 hr, 92 were the specific for giant cells. Four of these polypeptides were appeared within only 1 hr after the cell fusion. The other 405 were non-specific polypeptides which appeared in both giant cells and NC4 or/and HM1 cells. However, the patterns and the rates of production of each polypeptide during the incubation period were different between these cells.