MORE MOG GENES THAT INFLUENCE THE SWITCH FROM SPERMATOGENESIS TO OOGENESIS IN THE HERMAPHRODITE GERM-LINE OF CAENORHABDITIS-ELEGANS

The Caenorhabditis elegans XX animal possesses a hermaphrodite germ li ne, producing first sperm, then oocytes. In this paper, we report the genetic identification of five genes, mog-2, mog-3, mog-4, mog-5, and mog-6, that influence the hermaphrodite switch from spermatogenesis to oogenesis. In mog-2-mog-6 mutants, spermatogenesis continues past the time at which hermaphrodites normally switch into oogenesis and no oo cytes are observed. Therefore, in these mutants, germ cells are transf ormed from a female fate (oocyte) to a male fate (sperm). The fem-3 ge ne is one of five genes that acts at the end of the germline sex deter mination pathway to direct spermatogenesis. Analyses of mog;fem-3 doub le mutants suggest that the mog-2-mog-6 genes act before fem-3; thus t hese genes may be in a position to negatively regulate fem-3 or one of the other terminal regulators of germline sex determination. Double m utants of fem-3 and any one of the meg mutations make oocytes. Using t hese double mutants, we show that oocytes from any mog;fem-3 double mu tant are defective in their ability to support embryogenesis. This mat ernal effect lethality indicates that each of the meg genes is require d for embryogenesis. The two defects in mog-2-mog-6 mutants are simila r to those of mog-1: all six meg genes eliminate the sperm/oocyte swit ch in hermaphrodites and cause maternal effect lethality. We propose t hat the mog-2-mog-6 mutations identify genes that act with mog-1 to ef fect the sperm/oocyte switch. We further speculate that the mog-1-mog- 6 mutations all interfere with translational controls of fem-3 and oth er maternal mRNAs. (C) 1993 Wiley-Liss, Inc.