A shared transcriptional clock patterns neuronal fate in the Drosophila ventral nerve cord
A high-coverage developmental atlas of the Drosophila ventral nerve cord reveals a universal transcriptional clock of birth order, expressed as 17 shared transcription factors (shTFs) that align neurons across hemilineages, segments and sexes, enabling mapping between transcriptomic cell types and the connectome. The study shows embryonic-born neurons diverge earlier than larval-born ones, demonstrates how birth-order information shapes neuronal diversity, and uncovers sex-specific mechanisms—apoptosis and transcriptional divergence—in shaping dimorphisms, with Br acting as a terminal selector when misexpressed. The atlas provides a framework for linking molecular identity to circuit architecture and for comparative studies on nervous system development and evolution.