THE DES-1 PROTEIN, REQUIRED FOR CENTRAL SPINDLE ASSEMBLY AND CYTOKINESIS, IS ASSOCIATED WITH MITOCHONDRIA ALONG THE MEIOTIC SPINDLE APPARATUS AND WITH THE CONTRACTILE RING DURING MALE MEIOSIS IN DROSOPHILA-MELANOGASTER

Spermatogenesis in Drosophila melanogaster serves as an excellent mode l system for the isolation and analysis of genes required in the contr ol of chromosome segregation and cytokinesis. We report here the isola tion and molecular characterization of a novel P-element induced allel e of the des-1 gene, which leads to male sterility as a consequence of the failure of central spindle assembly in meiotic spermatocytes and the formation of aberrant meiotic end products characteristic of cytok inesis failure. We have raised affinity-purified antibodies against a Des-1 fusion protein, and localized the Des-1 protein in Drosophila sp ermatocytes. We show that the Des-1 protein is colocalized with mitoch ondria throughout male meiosis, becoming intimately associated with mi tochondria along the spindle apparatus during anaphase and telophase, and with the Nebenkern, or mitochondrial derivative, of the meiotic en d products. In addition, a significant association of Des-1 with the c ontractile ring is observed during anaphase and telophase of meiosis. These observations, together with the presence of six potential transm embrane domains in the Des-1 protein, raise the possibility that Des-1 may act as part of an anchoring mechanism that links membrane-bounded cellular compartments to components of the cytoskeleton.