Two different cDNAs code for L-DOPA decarboxylase in the white prepuparium and eclosion developmental stages of the insect Ceratitis capitata1.
In insects the DOPA decarboxylase gene (Ddc) is expressed in the epidermis where dopamine derivatives promote cuticle sclerotization and the central nervous system participating in the synthesis of serotonin and dopamine. The temporal course of Ddc enzyme activity during the white prepuparium and eclosion developmental stages primarily reflects this role. Here we report that a cDNA clone for l-DOPA decarboxylase (EC 4.1.1.28) has been isolated from the white puparium stage of the insect Ceratitis capitata, the cDNA sequence has been determined and it corresponds to an mRNA of 1341 base pairs. The comparison of this cDNA sequence with that of the eclosion stage which has been previously isolated in our laboratory revealed that the cDNA from the eclosion stage codes for protein consisting of 431 amino acid (aa) residues whereas that from the white prepuparium stage for protein of 425 aa residues. In addition there is a region of 33 aa residues close to the N-terminal region of the deduced protein in which marked differences in the aa composition are observed. This result was further confirmed by Northern blot analysis in which mRNAs isolated from both developmental stages were only hybridized with their respective polymerase chain reaction synthesized stage specific probes. These results suggest that during development of the insect C. capitata two different mRNAs are produced at the white prepuparium and the eclosion stages, giving rise to two protein isoforms presumably in response to different signals.