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. Author manuscript; available in PMC: 2015 Sep 23.
Published in final edited form as: Wiley Interdiscip Rev Dev Biol. 2013 Jun 28;3(1):69–81. doi: 10.1002/wdev.122

Figure 5. High-resolution neuronal lineage analysis by twin-spot MARCM.

Figure 5

(A) The adult Drosophila brain (gray) carries neurons with different characteristic morphologies that arise in clones from specific NBs. Exemplified in this illustration are representative neurons present in two antennal lobe (AL) NB clones (dashed circumferences). The anterodorsal AL (adAL) lineage yields distinct uniglomerular projection neurons (PNs), which each target one of the 50 or so AL glomeruli and then project through the MB calyx into the LH (e.g. the right-hemisphere blue neuron). Besides making uniglomerular PNs that target a different set of AL glomeruli (e.g. the left-hemisphere blue neuron), the lateral AL (lAL) lineage generates diverse AL local interneurons (LNs, e.g. the orange neuron) plus various non-AL PNs (e.g. the green neuron) that connect other neuropils. To map individual neurons and further elucidate the origins of neuron diversity requires tracking single neurons serially made by a common NB.

(B–D) Systematic analysis of GMC clones (red) paired with NB clones (green) of different sizes allows mapping of the serially derived neurons in the adAL lineage. Only one of the sister neurons derived from each adAL GMC survives into the adult stage, as the NB clones consistently associate with a single-neuron GMC clone. Notably, the uniglomerular adAL neurons that innervate different AL glomeruli are born sequentially in a defined order from the adAL NB. For instance, the VM3-, 1-, and DL2v-targeting neurons are born at the early (B), middle (C), and late (D) stages, respectively. Scale bar: 10 μm.

(E) The lAL NB clone (cell bodies marked with black asterisks) exhibits complex morphologies. Differential labeling of twin neurons derived from common GMCs consistently reveals one PN (magenta) paired with one LN (green) in the lAL lineage. Distinct PN/LN pairs are selectively recovered following clone induction (blue asterisks) in different two-hour windows after larval hatching (ALH), suggesting neuron fate specification based on the GMC birth order and the A/B binary fate decision. Scale bar: 10 μm.