Spatiotemporal resolution of the Ntla transcriptome in axial mesoderm development

Transcription factors play diverse roles during embryonic development, combinatorially controlling multiple cellular states in a spatially and temporally defined manner. Resolving the dynamic transcriptional profiles that underlie these patterning processes is essential for understanding embryogenesis at the molecular level. Here we show how temporal, tissue-specific changes in embryonic transcription factor function can be discerned by integrating caged morpholino oligonucleotides (cMOs) with photoactivatable fluorophores, fluorescence-activated cell sorting (FACS), and microarray technologies. As a proof of principle, we have dynamically profiled No tail-a (Ntla)-dependent genes at different stages of axial mesoderm development in zebrafish, discovering discrete sets of transcripts that are coincident with either notochord cell fate commitment or differentiation. Our studies reveal new regulators of notochord development and the sequential activation of distinct transcriptomes within a cell lineage by a single transcriptional factor, demonstrating how optically controlled chemical tools can dissect developmental processes with spatiotemporal precision.