huckebein encodes a putative zinc finger protein expressed in a subset of Drosophila CNS precursors, including the NB 4-2/GMC 4-2a/RP2 cell lineage. Inhuckebein mutant embryos, GMC 4-2a does not express the cell fate marker EVEN-SKIPPED; conversely,huckebein overexpression produces a duplicate EVEN-SKIPPED-positive GMC 4-2a. We use Dil to trace the entire NB 4-2 lineage in wild-type andhuckebein mutant embryos. Loss ofhuckebein does not affect the number, position, or type of neurons in the NB 4-2 lineage; however, all motoneurons show axon pathfinding defects and never terminate at the correct muscle. Thus,huckebein regulates aspects of GMC and neuronal identity required for proper motoneuron axon pathfinding in the NB 4-2 lineage.
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