During early development in the nematode Caenorhabditis elegans, cues from the sperm trigger completion of meiosis by the oocyte chromosomes and establishment of the anterior-posterior axis. Little is known about the control of these events and their possible interdependence. To study this, we are analyzing a mutant in C. elegans, called
scu-1 ( s perm cu e abnormal) which has defects in both meiotic exit and anterior-posterior axis formation in the one-cell embryo. Interestingly, the
scu-1 gene shows a partial paternal requirement, as reduced viability of embryos is observed from crosses involving either
scu-1 mutant eggs with wild-type sperm or wild-type eggs with
scu-1 mutant sperm. P> P> In an attempt to better understand the maternal and paternal requirements for the
scu-1 gene product in meiotic exit and polarity, we are performing mel and pel crosses in which either eggs or sperm are mutant for
scu-1, and examining the resulting embryos via time-lapse imaging under DIC optics. As some embryos produced from these crosses survive to adulthood, it is not surprising that some of the embryos we've examined so far look completely wild-type during the first cell division. We are continuing these crosses in the hope of uncovering if any maternal or paternal specific defects will be observed. P> P> In addition to analysis of maternal and paternal
scu-1 contributions in embryos, we are beginning to look at the meiotic defects of
scu-1 mutants in more detail. Previously, meiotic defects have been observed in embryos produced by
scu-1 mutant hermaphrodites. We are now in the process of determining if similar defects are observed during sperm production in
scu-1 mutant males. In addition, as chromosome segregation defects are occasionally observed during oocyte meiosis in
scu-1 mutant embryos, we are testing to see if
scu-1 mutant hermaphrodites produce an overabundance of males due to nondisjunction of the X chromosome. It is our hope that these studies will result in a clearer picture of the role for
scu-1 during meiosis and the role of maternal and paternal SCU-1 during early development.