Twin-Spot MARCM to reveal developmental origin and identity of neurons

A comprehensive understanding of the brain requires analysis of individual neurons. Here we describe twin-spot MARCM for high-resolution lineage tracing by independent labeling of paired sister clones. We determine patterns of neurogenesis and the influences of lineage on neuron-type specification. Notably, neural progenitors may yield intermediate precursors that make one, two, or more neurons. Furthermore, neurons acquire stereotyped projections according to their temporal position within various brain sublineages. Twin-spot MARCM also permits birth dating of mutant clones, enabling the detection of a single temporal fate that requires chinmo in a sublineage of six Drosophila central complex neurons. In sum, twin-spot MARCM can reveal the developmental origins of neurons and the mechanisms that underlie cell fate.