The Notch locus of Drosophila melanogaster: A molecular analysis

Abstract

AbstractGenetic analysis has suggested that neurogenesis in D melanogaster is under the control of a small number of genes. We have initiated a molecular study of the genes involved in this developmental event and started our analysis with the Notch locus, which is one of the best characterized loci in D melanogaster in terms of its genetic structure and developmental effects. In this paper we report on the molecular characterization of the Notch locus.We describe the molecular cloning of Notch and present evidence that the entire locus is defined by approximately 40 kb of genomic DNA. The transcriptional activity of these sequences during development has been examined and the results indicate that an approximately 10.5‐kb‐long poly A+ RNA is essential for wild type Notch activity. Mapping of this RNA within the physical map of Notch indicates that it is the processed product of an approximately 40‐kb primary transcription unit spanning the entire Notch locus. More detailed analysis of the 10.5 kb RNA localizes several exons and identifies a small repetitive sequence that seems to be present in the mature Notch transcript. Structural details of a selected number of Notch locus mutations are presented and discussed. Preliminary data on the molecular structure of Notch‐homologous DNA sequences in closely related species are also presented.