Two different cDNAs code for L-DOPA decarboxylase in the white prepupariumand eclosion developmental stages of the insect Ceratitis capitata

In insects the DOPA decarboxylase gene (Ddc) is expressed in the epidermis where dopamine derivatives promote cuticle sclerotization and the central n ervous system participating in the synthesis of serotonin and dopamine. The temporal course of Ddc enzyme activity during the white prepuparium and ec losion developmental stages primarily reflects this role. Here we report th at a cDNA clone for L-DOPA decarboxylase (EC 4.1.1.28) has been isolated fr om the white puparium stage of the insect Celatitis capitata, the cDNA sequ ence 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) resi dues whereas that from the white prepuparium stage for protein of 425 aa re sidues. In addition there is a region of 33 aa residues close to the N-term inal region of the deduced protein in which marked differences in the aa co mposition are observed. This result was further confirmed by Northern blot analysis in which mRNAs isolated from both developmental stages were only h ybridized with their respective polymerase chain reaction synthesized stage specific probes. These results suggest that during development of the inse ct C. capitata two different mRNAs are produced at the white prepuparium an d the eclosion stages, giving rise to two protein isoforms presumably in re sponse to different signals. (C) 1998 Elsevier Science B.V. All rights rese rved.