The actin network is disrupted in mutant embryos in cycle 13 metaphase.
Embryos derived from dal1 mutant females produce mitotic errors that lead to loss of approximately 1/2 of the syncytial nuclei during divisions 10 to 13.
Affected embryos develop distinct defects in the cortical cytoskeleton.
Embryos develop normally until cycle 10 then at cycle 12, 13 and 14 many abnormal nuclei fall to the interior of the embryo resulting in embryos that cellularize at one half of the normal nuclear density. The abnormal nuclei have centromeres of an abnormal size and spacing near their surface, they have failed to separate normally in the previous interphase. The nuclear abnormalities in dal1 embryos are telophase fusion and failure nuclear division. Older embryos have a large excess of internal nuclei. There are some adult escapers despite the severe nuclear abnormalities: they may suffer loss of an appendage or abnormally arranged tergites.
External phenotype normal. Shows reduced survival in heterozygous combination with deficiency. Maternal effect embryonic lethal with relative survival of sons less than that of daughters. Maternal effect more severe at 25oC than at 19oC. Maternal effect reduced by presence of Y or Xh in zygotes. Presence of dal+ allele increases survival of offspring of abo mothers.
