Cellular and axonal migrations are misguided along both body axes in the maternal-effect mau-2 mutants of Caenorhabditis elegans.

We have characterized the mau-2 mutants of Caenorhabditis elegans and found that migrating cells and axons are mispositioned along both the antero-posterior and dorsoventral body axes. This is in contrast to previously characterized guidance mutations in Caenorhabditis and in Drosophila, which have been found to be axis-specific. Two observations suggest that mau-2 acts very early during development: most behavioral phenotypes of mau-2 can be rescued by a maternal effect, and variations in expressivity involve an entire body side at a time. The possibility that mau-2 is involved in the spatial organization of guidance cues encoded by other genes is discussed.