The embryonic lethal mutation zyg-10(b261) is an allele of the atx-2 gene and disrupts multiple aspects of early embryogenesis.

The zyg-10 ( b261 ) mutation was identified in one of the earliest screens for temperature-sensitive embryonic lethal mutations in C. elegans , but the cytological defects underlying the embryonic lethal phenotype, as well as the molecular identity of zyg-10 had not been previously established. Here we show that zyg-10 ( b261 ) is an allele of the atx-2 (ataxin-related) gene and that embryos produced by atx-2 ( b261 ) mothers exhibit a variety of defects including eggshell defects, cytokinesis failure, spindle mispositioning, and chromosome missegregation. We also show that the localization of separase, a regulator of egg-shell formation and mitosis, is defective in atx-2 ( b261 ) embryos.