MUTATION OF A GENE FOR A DROSOPHILA KINESIN-LIKE PROTEIN, KLP38B, LEADS TO FAILURE OF CYTOKINESIS

Mutations in a gene (Klp38B) encoding a novel kinesin-like protein in Drosophila melanogaster lead to the formation of polyploid cells in th e larval central nervous system and in the follicle cells of adult egg chambers, Some homozygous mutants survive to adulthood and also exhib it morphological defects indicative of abnormal cell cycle progression , including rough eyes, missing bristles, and abnormal abdominal cutic les, In larval brains, there is no accumulation of mitotic cells and t he frequency of anaphase figures is comparable to wild type, suggestin g that nuclear division is not affected, Such brains contain polyploid cells with metaphase and anaphase chromosomes associated with bipolar spindles, Such spindles have a number of unseparated centrosomes at t heir poles reflecting the degree of polyploidy of the cell, Follicle c ells frequently contain two nuclei of roughly equal size, Taken togeth er, we conclude that these Klp38B mutations lead to a failure of cytok inesis resulting in polyploidy, and discuss whether or not this is a d irect effect of the mutation.