The overall goal of this laboratory's research is to understand on a molecular level how the eukaryotic cell achieves its very efficient and closely regulated synthesis of rRNA, which comprises over 75% of the total cellular RNA. In the previous studies we demonstrated systems for in vitro and in vivo expression of Xenopus and mouse rDNA, localized the promoter sequences, and studied the cellular components responsible for this expression and its regulation. We now wish to extend these studies, and to that end propose to examine the action of upstream rDNA transcriptional elements: the frog 60/81 bp repeats and 0/1 repeats, the mouse 140 bp repeats and the mouse spacer promoter region. We propose a number of in vivo and in vitro experiments to determine whether the enhancer repeats function via chromatin assembly, whether they affect the number or activity of active rRNA genes, whether and how they affect factor binding to the promoter, and their dependence upon helical face and ongoing transcription.***//
