Recording morphogen signals reveals mechanisms underlying gastruloid symmetry breaking

We engineered mouse embryonic stem cells to express reporters and recorders developmental signals, and traced how early signaling states predict cell fates. For single cell sequencing analysis, we collected and dissociated gastruloids at both 96 hours after aggregate ("t96") and 120 hours after aggregation ("t120"). For the 120 h sample, we also recording Wnt signaling activity earlier at 96 h, and used fluorescence activated cell sorting (FACS) to separate Wnt-recorded cells based on a GFP signal ("G") from those in which Wnt was not recorded ("R")