MORPHOGENESIS OF DROSOPHILA OVARIAN RING CANALS

We analyzed the structure of cytoplasmic bridges called ring canals in Drosophila egg chambers. Two mutations, hu-li tai shao (hts) and kelc h, disrupt normal ring canal development. We raised antibodies against the carboxy-terminal tail of hts and found that they recognize a prot ein that localizes specifically to ring canals very early in ring cana l assembly. Accumulation of filamentous actin on ring canals coincides with the appearance of the hts protein. kelch, which is localized to the ring canals hours after hts and actin, is necessary for maintainin g a highly ordered ring canal rim since kelch mutant egg chambers have ring canals that are obstructed by disordered actin and hts. Anti-pho sphotyrosine antibodies immunostain ring canals beginning early in the germarium before hts and actin and throughout egg chamber development . The use of antibody reagents to analyze the structure of wild-type a nd mutant ring canals has shown that ring canal development is a dynam ic process of cytoskeletal protein assembly, possibly regulated by tyr osine phosphorylation of some ring canal components.