Maternal effects on postembryonic neuroblast migration in Caenorhabditis elegans.

Maternal-effect genes mostly regulate early embryogenesis as their mRNAs or proteins are deposited into the oocytes to function during early embryonic development before the onset of zygotic transcription. Here, we report a case where a maternal-effect gene regulates postembryonic neuroblast migration long after the early embryonic stages. We found that the defects of the Q neuroblast migration in Caenorhabditis elegans mannosyltransferase dpy-19 mutants can be rescued by a maternal copy of the gene. Maternal dpy-19 mRNAs are deposited into the oocytes and persist throughout embryonic development into the Q cells to regulate their migration in early larval stages. These mRNAs appeared to be remarkably stable, since long-term developmental arrest, changing the 3'UTR sequence, and mutations in genes involved in RNA binding and modification all had weak effects on the maternal rescue of the neuroblast migration defects. Since the defects can also be rescued by a zygotic copy of dpy-19(+), our results suggest that postembryonic neurodevelopment is redundantly regulated by maternal and zygotic copies of the same gene.