The cloning and expression of the gene encoding organ-specific esterase S from the genome of Drosophila virilis.

We have cloned the gene for the esterase S isozymes complex from the genome of Drosophila virilis in pBR322. Esterase S is an enzyme which is specifically synthesized in the ejaculatory bulbs of D. virilis adult males. The gene for the esterase S isozyme complex (estS) has been localized in band 2G5e of chromosome II. Poly(A)+ RNA prepared from ejaculatory bulbs actively hybridizes with this band. A cloned 15-kb fragment of D. virilis DNA (pVE9) also hybridizes with band 2G5e. The area encoding the poly(A)+ RNA is located in the middle part of the cloned fragment whose ends are not transcribed in vivo. Only one poly(A)+ RNA which is 1.9 kb long and complementary to pVE9 DNA can be revealed in the cytoplasm. The mRNA preselected by hybridization to pVE9 DNA was microinjected into the cytoplasm of Xenopus laevis oocytes. In other experiments, the pVE9 DNA itself was microinjected into oocyte nuclei. In both cases, esterase S is synthesized in the oocytes, and the major part of the protein is transported from the oocytes and accumulated in the incubation medium.