The bithorax complex (BX-C) plays a key role in the determination and maintenance of segmental identity during development of the fruit fly, Drosophila melanogaster. This large gene complex is well characterized genetically and is now slowly yielding to molecular analysis. However, the means by which the genes of the BX-C are so precisley regulated are not understood, and characterization of the huge regulatory regions of the complex has just begun. The work described in this proposal contributes to the molecular analysis of the abdominal region of the BX-C, addressing specifically the question, what is the role of the infra- abdominal-5,7 (iab-5,7) region? Does it serve as a large cis-regulatory region for the adjacent Abdominal-B gene? What is the function of the transcripts encoded within this region? Is the entire region essential for normal function? Four major projects are proposed: (1) Recovery of new mutations within the iab-5,7 region using mutagenic agents which cause small deletions or insertions. (2) Characerization of Abdominal-B transcript distribution in mutants of the iab-5,7 region by Northern analysis and in situ hybridization to RNA in embryonic tissue sections. (3) Analysis of transcripts encoded within the iab-5,7 region by Northern analysis and isolation and characterization of cDNAs. (4) Determination of the genomic sequence of the entire region. These studies will contribute to our understanding of some of the complex genetic functions and interactions that occur during the development of a higher eukaryote.
