A MUTATION (DOSACH) IN DROSOPHILA WHICH AFFECTS ASTER FORMATION AND NUCLEAR MIGRATION DURING CLEAVAGE

Here we describe a new mutant, dosach (dos), in Drosophila melanogaste r. In the mutant, centrosomes divide and initiate spindle formation si milar to that seen in wild-type embryos. Nevertheless, mutant embryos form cleavage spindles that lack visible asters and display abnormal m orphology, including mono- and tri-polar spindles, spindle chains and incorrect alignment. Irregular nuclear migration is also observed in m utant embryos, and this may suggest that astral microtubules are impor tant for spindle spacing during cleavage and also in maintaining the i ntegrity of the mitotic apparatus. Confocal microscopy has been used t o correlate organization of microtubules, centrosomal proteins and chr omosomes in wild-type and dosach (dos) embryos.