It ain't over till it's ova: germline sex determination in C-elegans

Sex determination in most organisms involves a simple binary fate choice be tween male or female development; the outcome of this decision has profound effects on organismal biology, biochemistry and behaviour. In the nematode C. elegans, there is also a binary choice, either male or hermaphrodite. I n C. elegans, distinct genetic pathways control somatic and germline sexual cell tate. Both pathways share a common set of globally acting regulatory genes; however, germline-specific regulatory genes also participate in the decision to make male or female gametes. The determination of sexual fate i n the germline of the facultative hermaphrodite poses a special problem, be cause first sperm then oocytes are produced. It has emerged that additional layers of post-transcriptional regulation have been imposed to modulate th e activities of the global sex-determining genes, tra-2 and fem-3; the bala nce between these activities is crucial in controlling sexual cell fate in the hermaphrodite germline. BioEssays 23:596-604, 2001, (C) 2001 John Wiley & Sons, Inc.