Chromatin and Transcriptional Regulation in Drosophila Salivary Gland Development. Michael B. Wells, Deborah J. Andrew. Department of Cell Biology, Johns Hopkins University, Baltimore, MD.

   Salivary gland development involves an intricate balance of combinatorial signaling inputs over discrete and prolonged intervals. The molecular players that contribute to this process are known, but less is understood about how the genes encoding these proteins are regulated. Using available high-resolution data, we have begun to characterize the chromatin and transcriptional landscape of several genes important to salivary gland development at multiple developmental stages. These data strengthen previous reports that fkh regulation involves the balance between Polycomb and Trithorax signaling, and indicate that regulation of this balance is, in fact, critical at the loci of most components of salivary gland development. They also suggest that RNA polymerase II pausing plays a role in establishing the proper timing of transcription of several important salivary gland contributors (crb, CrebA, hth, Scr, and tsh). Further, these data indicate that differential enhancer utilization and nucleosome remodeling are important to proper expression of the salivary gland gene sage. We are currently exploring these findings in more detail using molecular biology methods including immunoFISH, RT-qPCR, and in situ hybridization. Finally, we are also determining whether this regulation remains important in adult flies for salivary gland maintenance as well as the extent to which salivary gland development and this chromatin and transcriptional regulation are conserved with respect to Drosophila melanogaster in the mosquito malarial vectors Anopheles gambiae and Anopheles stephensi.