ISOLATION AND CHARACTERIZATION OF THE DROSOPHILA ORNITHINE DECARBOXYLASE LOCUS - EVIDENCE FOR THE PRESENCE OF 2 TRANSCRIBED ODC GENES IN THE DROSOPHILA GENOME

The polymerase chain reaction (PCR) was used to isolate two Drosophila ornithine decarboxylase (ODC) genes. Two mixtures of degenerate oligo nucleotides corresponding to peptides that are fully conserved among O DCs from widely diverged species were used as opposing primers in the PCR with cDNA or genomic DNA as templates. Sequence analysis of the re sulting DNA products confirmed their identity as ODC fragments. The ge nomic PCR product was then used as a probe for screening a Drosophila genomic library, resulting in the isolation of genomic clones represen ting two distinct ODC genes (dODC1 and dODC2). Sequence analysis of bo th genes demonstrated that although varying at their coding and noncod ing regions, their overall structure is extremely similar containing 6 exons and 5 short introns. Southern blot and sequence analyses reveal ed that the two ODC genes are arranged in a tandem head-to-tail config uration. Both ODC genes were assigned by in situ hybridization analysi s to position 44A on the right arm of the second chromosome. The isola tion of cDNA clones Corresponding to these two ODC genes demonstrated that both are transcribed in the adult fly. We hope that the isolation of genomic and cDNA clones of Drosophila ODC will permit the investig ation of the expression of ODC during Drosophila development and the r ole of polyamines in this process.