Deletion of dah sequences.
Homozygous females lay eggs with normal morphology but the embryos fail to develop to the gastrulation stage; there are extensive disruptions in the actin hexagonal arrays. Development is normal up to nuclear stage 13 and extensive nuclear fusion starts after this stage. Abnormal nuclear morphology is correlated with cytoskeletal structure defects, cleavage furrow is grossly disrupted. Mutant phenotype can be rescued by dah+tDSR.