asunder is required for dynein localization and dorsal fate determination during Drosophila oogenesis
asunder is required for dynein localization and dorsal fate determination during Drosophila oogenesis
Poojitha Sitaram, Julie A. Merkle1, Ethan Lee, Laura A. Lee
Abstract
We previously showed that asunder (asun) is a critical regulator of dynein localization during Drosophila spermatogenesis. Because the expression of asun is much higher in Drosophila ovaries and early embryos than in testes, we herein sought to determine whether ASUN plays roles in oogenesis and/or embryogenesis. We characterized the female germline phenotypes of flies homozygous for a null allele of asun (asund93). We find that asund93 females lay very few eggs and contain smaller ovaries with a highly disorganized arrangement of ovarioles in comparison to wild-type females. asund93 ovaries also contain a significant number of egg chambers with structural defects. A majority of the eggs laid by asund93 females are ventralized to varying degrees, from mild to severe; this ventralization phenotype may be secondary to defective localization of gurken transcripts, a dynein-regulated step, within asund93 oocytes. We find that dynein localization is aberrant in asund93 oocytes, indicating that ASUN is required for this process in both male and female germ cells. In addition to the loss of gurken mRNA localization, asund93 ovaries exhibit defects in other dynein-mediated processes such as migration of nurse cell centrosomes into the oocyte during the early mitotic divisions, maintenance of the oocyte nucleus in the anterior-dorsal region of the oocyte in late-stage egg chambers, and coupling between the oocyte nucleus and centrosomes. Taken together, our data indicate that asun is a critical regulator of dynein localization and dynein-mediated processes during Drosophila oogenesis.