GENETIC AND MOLECULAR STUDIES OF APTEROUS - A GENE IMPLICATED IN THE JUVENILE-HORMONE SYSTEM OF DROSOPHILA

The apterous (ap) gene in Drosophila melanogaster encodes a homeodomai n transcription factor. It is required for the development of the wing s and of a subset of embryonic muscles. The gene has been implicated i n the juvenile hormone (JH) system because mutations in ap lead to JH deficiency, and are associated with defective histolysis of the larval fat body, arrested vitellogenesis, sterility, and aberrant sexual beh avior, all of which are dependent on JH. We describe here the use of h emizygotes and germ-line clones, of X-ray- and hybrid dysgenesis-induc ed lethal ap alleles to determine the primary role of the gene during development. We find that ap lethality is polyphasic, but occurs prima rily at the larval and pupal stages. The lethal phenotype is not assoc iated with any overt morphological abnormality, suggesting that death occurs from a systemic malfunction. Strong interallelic complementatio n for the wing phenotype was found between some ap mutations induced b y X-rays or by hybrid-dysgenesis. By Northern blot analysis, we demons trate an increase in ap expression in pupae and adults as compared to embryos and larvae, suggesting that it is developmentally regulated. F inally, primer extension is used to determine the transcription start site of the gene. (C) 1995 Wiley-Liss, Inc.