MATERNAL REPRESSION OF THE P-ELEMENT PROMOTER IN THE GERMLINE OF DROSOPHILA-MELANOGASTER - A MODEL FOR THE P-CYTOTYPE

The transposition of P elements in Drosophila melanogaster is regulate d by products encoded by the P elements themselves. The P cytotype, wh ich represses transposition and associated phenomena, exhibits both a maternal effect and maternal inheritance. The genetic and molecular me chanisms of this regulation are complex and not yet fully understood. In a previous study, using P-lacZ fusion genes, we have shown that P e lement regulatory products were able to inhibit the activity of the P promoter in somatic tissues. However, the repression observed did not exhibit the maternal effect characteristic of the P cytotype. With a s imilar approach, we have assayed in vivo the effect of P element regul atory products in the germline. We show that the P cytotype is able to repress the P promoter in the germline as well as in the soma. Furthe rmore, this repression exhibits a maternal effect restricted to the ge rmline. On the basis of these new observations, we propose a model for the mechanism of P cytotype repression and its maternal inheritance.