The projects in our laboratory focus on how regulatory complexes alter chromatin structure at scales that include short clusters of nucleosomes, kilobase-sized domains, and, within phase separated puncta. The focus is on complexes and regulatory RNAs that can alter these interactions. We use prior genetic studies on development, primarily those on the Polycomb-Group (PcG) and trithorax-group (trxG), to define complexes that we study. These complexes regulate the classic epigenetic paradigm of stable memory of cell type across numerous generations of cell divisions. Understanding their mechanism should lead to general insights on how transcriptional memory is maintained across mitosis and meiosis in mammals.