The selector gene cut represses a neural cell fate that is specified independently of the Achaete-Scute-Complex and atonal

The peripheral nervous system (PNS) of Drosophila offers a powerful system to precisely identify individual cells and dissect their genetic pathways o f development. The mode of specification of a subset of larval PNS cells, t he multiple dendritic (md) neurons (or type II neurons), is complex and sti ll poorly understood. Within the dorsal thoracic and abdominal segments, tw o md neurons, dbd and dda1, apparently require the proneural gene amos but not atonal (ato) or Achaete-Scute-Complex (ASC) genes. ASC normally acts vi a the neural selector gene cut to specify appropriate sensory organ identit ies. Here, we show that dbd- and dda1-type differentiation is suppressed by cut in dorsal ASC-dependent md neurons. Thus, cut is not only required to promote an ASC-dependent mode of differentiation, but also represses an ASC - and are-independent fate that leads to dbd and dda1 differentiation. (C) 2001 Elsevier Science Ireland Ltd. All rights reserved.