Neuronal acetylcholine receptors in Drosophila: mature and immature transcripts of the ard gene in the developing central nervous system.

The ARD protein is a Drosophila homolog of vertebrate nicotinic acetylcholine receptor (AChR) polypeptides. Here, an analysis of transcripts of the corresponding ard gene is presented. In situ hybridization experiments revealed ard gene expression in nervous tissue only. During development, ard transcripts are prevalent in late embryos, pupae, and newly eclosed flies. Both the spatial and the temporal pattern of ard gene expression is consistent with the ARD protein being part of a neuronal AChR that is produced in large amounts during major periods of neuronal differentiation. In situ hybridization with an intron-specific probe indicated codistribution of immature and mature ard RNAs in pupae and adult flies. In addition to the mature 3.2 kb RNA species, two large immature transcripts are found in newly eclosed flies but not in embryos, suggesting a developmentally regulated processing of ard RNA.