As an ISCRM Fellow, Scott Schactler is characterizing the microenvironment of the lncRNA Xist during X-chromosome inactivation using photocatalyst-powered super-resolution proximity-labeling tools. Using Oligonucleotide-directed proximity-interactome MAPing (O-MAP) in a cell model of early embryogenesis will reveal a pioneering map of the X-chromosome inactivation assembly pathway. Further developing the O-MAP method for even higher-resolution analysis of RNA-chromatin dynamics during cell fate determination will elucidate fundamental molecular mechanisms of stem cell biology and establish powerful tools for probing the RNA interactions that control stemness.