The Role of tbc-1 in Drosophila Salivary Gland Development. Dorothy M Johnson, Deborah Andrew. Cell Biology, Johns Hopkins School of Medicine, Baltimore, MD.

   Rabs are small GTPases involved in vesicle targeting, tethering, and fusion. Rabs GTPase activity is accelerated by Rab-GAPs (GTPase activating proteins). Recently, a highly conserved Drosophila Rab-GAP, known as tbc-1, was discovered to be expressed in the embryonic salivary gland under control of the FoxA transcription factor Fork head (Fkh). An analysis of deficiencies and RNAi of tbc-1 revealed irregular apical membranes in embryos in which tbc-1 was knocked down in the salivary gland, suggesting that tbc-1 has a role in salivary gland development. Based on these preliminary findings, tbc-1 knockout lines were generated by homologous recombination and verified by PCR analysis. Future plans include a full characterization of the null salivary gland and border cell migration phenotypes, as well as studies to learn which Rab and which membrane fusion events are normally modulated by this GTPase.