Genes required for GLP-1 asymmetry in the early Caenorhabditis elegans embryo

The translation of maternal glp-1 mRNA is regulated both temporally and spatially in the early Caenorhabditis elegans embryo (T. C. Evans, S. L. Crittenden, V. Kodoyianni, and J. Kimble, Cell 77, 183-194, 1994). To investigate the control of embryonic glp-1 expression, we have examined the distribution of GLP-1 protein in selected maternal effect mutants that affect pattern or fate in the early embryo. We find that mutants that disrupt anterior-posterior asymmetry in the early embryo (par-1-par-6, emb-8, Par(q537)) disrupt the spatial but not temporal control of GLP-1 expression: GLP-1 is observed at the normal stage of embryogenesis in par-like mutants; however, it is uniformly distributed. In contrast, mutants that alter blastomere identity (skn-1, pie-1, mex-1, apx-1) do not affect the normal GLP-1 pattern. We conclude that genes controlling the asymmetry of cellular components, including P granules, also control GLP-1 asymmetry in the early embryo. The finding that mutants that disrupt anterior-posterior asymmetry translate GLP-1 in all blastomeres suggests that loss of embryonic asymmetry causes translational activation of GLP-1 in the posterior.