Diverse expression of dsrc29A, a gene related to src, during the life cycle of Drosophila melanogaster.

We used in situ hybridization to study the RNA expression of the dsrc29A gene during Drosophila development. This gene encodes two proteins differing at their amino termini. Both gene products contain a protein-tyrosine kinase domain and resemble the protein encoded by vertebrate src. We examined most stages of development in the Drosophila life cycle: embryos, third instar larvae, pupae and adults. Our results revealed that dsrc29A expression is specialized throughout development, being prominent at various times in neural tissue, phagocytic cells, dorsal vessel, ovaries, gut, developing salivary glands, imaginal discs and disc derivatives. These findings confirm and extend previous results for the distribution of dsrc29A protein, indicating that the regulation of this gene is primarily at the level of transcription. In some tissues expression is transient, whereas in others, it is continuous, and expression occurs in proliferative, differentiating and differentiated tissue. These patterns of expression demonstrate how a single protein-tyrosine kinase might play diverse roles at different times during development. Comparison of the expression of dsrc29A and other members of the protein-tyrosine kinase gene superfamily reveals that the genes are expressed in distinctive but sometimes overlapping patterns.