The long-term objective of this work is to understand the role of signalling molecules in growth control and pattern formation. The focus of this proposal is the characterization of a novel Drosophila melanogaster growth factor gene, defective dorsal discs. The objectives are to extend the molecular characterization of the ddd gene and identify genes in the same signalling pathway. The region encompassing seven DNA lesions that cause ddd phenotypes has been cloned but because off repetitive motifs, and rarity of the message, no transcription unit has been found. Two approaches will be used to identify the transcription unit: in situ hybridization to tissues using probes from the region, and sequence conservation with Drosophila virills. Probes from the transcribed region will be used to isolate cDNAs which will be sequenced to predict the encoded protein. Genomic DNA will be sequenced if no cDNA can be isolated. The transcription pattern during development will be described. Phenotypically related genes will be mapped, checked for complementation with known genes, and cloned by plasmid rescue.
