THE DIFFERENTIATION OF A CELL SORTING MUTANT OF DICTYOSTELIUM-DISCOIDEUM

As a result of transfecting Dictyostelium discoideum with an actin 6// lacZ fusion transgene, strain HW80 was created which expresses the bet a-galactosidase gene product uniformly throughout development. When mi xed with an excess of unmarked wild-type cells, however, HW80 cells se lectively migrate to the positions of anterior-like cells surrounding the prespore cell mass, and differentiate as if they were anterior-lik e cells. As the proportion of HW80 cells is increased, they also sort to positions adjacent to anterior-like cells and some differentiate as prespore cells. Thus sorting of HW80 cells toward the opposite ends o f the prespore cell zone supersedes how they differentiate, suggesting that position influences whether cells differentiate as anterior-like or prespore cells.