ROUGHEX IS A DOSE-DEPENDENT REGULATOR OF THE 2ND MEIOTIC DIVISION DURING DROSOPHILA SPERMATOGENESIS

During spermatogenesis, germ cells execute two meiotic divisions, then withdraw from the cell cycle and initiate postmeiotic differentiation . We show that the gene roughex (rux) is a dose-dependent regulator of meiosis II during Drosophila spermatogenesis. rux mutant germ cells e xecute the two meiotic divisions, but then undergo an additional M pha se resembling an extra meiosis II. Conversely, germ cells with excess rux function fail to undergo meiosis II. rux does not appear to act di rectly at meiosis II. Rather, rux appears to act through cyclin A duri ng premeiotic G2 to regulate meiosis II. We propose that cyclin A-cdc2 kinase at the G2 to M transition of meiosis I activates a target nece ssary for meiosis II, thereby coupling the two meiotic divisions.