Fig. 3. Genetics and active model of PSR-induced genome elimination.

(A) The effects of RNAi knockdown of haploidizer on PSR transmission and the proportion of female offspring. The pie charts indicate the proportion of males (gray) and females (purple). (B) Model for involvement of haploidizer in PGE. Expression of PSR’s haploidizer gene leads to failure of the paternal chromatin to resolve into chromosomes. This action inhibits the activation of female transformer (traF) and, thus, female development. As a result, these fertilized eggs develop into haploid male offspring that carry PSR. RNAi treatment of haploidizer mitigates the chromatin defects, allowing partial expression of traF from the paternal set. This action reestablishes the female developmental pathway.