Fig. 1

NB7–1 generates an Eve⁻ Nkx6⁺ motor neuron. a-d The NB7–1 lineage is labeled with GFP (green). One hemisegment of a stage 16 embryo is shown (except where noted); ventral midline, dashed line. Eve⁺ Zfh1⁺ U1-U5 motor neurons, white circles; Eve⁻ Zfh1⁺ motor neuron, yellow circle. Neurons are montaged from different z-axis positions with their X-Y position preserved (see Methods). Left column: Eve marks U1-U5 motor neurons. Middle column: Zfh1 marks all motor neurons, although in U2 motor neurons, Zfh1 staining is fainter. Additional Zfh1⁺ motor neurons can be seen outside the GFP⁺ lineage. Right column: Kr is expressed in U1-U3 and the Eve⁻ Zfh1⁺ presumptive VO neuron. Pdm is expressed in the Eve⁻ Zfh1⁺ presumptive VO motor neuron and the Eve⁺ U4-U5 motor neurons. Note that Pdm is shown at stage 13 before it fades. Hey is expressed in U1-U5 and the presumptive VO motor neuron, indicating they are all Notch-ON progeny from different GMCs. Note that Hey expression declines after GMC division, resulting in higher Hey levels in the latest born motor neurons (U4/U5). Nkx6 is expressed in the Eve⁻ Zfh1⁺ presumptive VO motor neuron (yellow circle) and other neurons outside the lineage. Scale bar: 10 μm. Far right column: summary. e Proposed NB7–1 lineage