The Drosophila proneural gene amos promotes olfactory sensillum formation and suppresses bristle formation

Proneural genes encode basic-helix-loop-helix (bHLH) transcription factors required for neural precursor specification. Recently amos was identified as a new candidate Drosophila proneural gene related to atonal . Having isolated the first specific amos loss-of-function mutations, we show definitively that amos is required to specify the precursors of two classes of olfactory sensilla. Unlike other known proneural mutations, a novel characteristic of amos loss of function is the appearance of ectopic sensory bristles in addition to loss of olfactory sensilla, owing to the inappropriate function of scute . This supports a model of inhibitory interactions between proneural genes, whereby ato -like genes ( amos and ato ) must suppress sensory bristle fate as well as promote alternative sense organ subtypes.