MOLECULAR CHARACTERIZATION OF THE NOTCH HOMOLOG FROM THE AUSTRALIAN SHEEP BLOWFLY, LUCILIA-CUPRINA

The Drosophila melanogaster Notch gene product functions as a receptor of intercellular signals and is central to cell fate specification. T he Scalloped wings (Scl) gene is the homologue of Notch in the Austral ian sheep blowfly, Lucilia cuprina. An allele of Scl is thought to be involved in the modification of Darwinian fitness and bristle asymmetr y in flies resistant to organophosphorous chemicals (OPs). As a first step towards the testing of this hypothesis we cloned and sequenced Sc l. A full-length cDNA segment representing the mRNA of Scl is 8503 bp and encodes a protein of 2653 amino acids, which shares 73.6% identity with Notch. All functional motifs including EGF-like repeats, LNR rep eats, cdc10/ankyrin repeats, opa and PEST elements are present in the same order as in Notch and the sequence identities peak in these motif s. With respect to genomic structure, intron/exon boundaries are conse rved but, in most cases, the Scl introns are larger. Sequence analysis of the upstream genomic region reveals that the gene has a TATA-less promoter. Consistent with a central role in embryogenesis and imaginal development, high levels of Scl expression were detected in the early embryonic and pupal stages. (C) 1998 Published by Elsevier Science Lt d. All rights reserved.