ROLE OF CATECHOLAMINES AND BETA-ALANINE IN PUPARIAL COLOR OF WILD-TYPE AND MELANIC MUTANTS OF THE MEDITERRANEAN FRUIT-FLY (CERATITIS-CAPITATA)

Ceratitis capitata prepupae were microinjected with beta-alanine (BALA ) and/or dopamine at the onset of pupariation to manipulate the phenot ypes of wild-type and mutant strains, A mutant strain, Black pupa (B), reverted to the wild-type phenotype when injected with BALA, whereas black puparial cuticle was partially maintained when dopamine was co-i njected with BALA, Phenocopies of the B mutant strain were obtained wi th injections of dopamine into wild-type prepupae, but partial or tota l inhibition of melanization occurred when BALA was co-injected, The p uparial phenotype of another melanic mutant, niger (nig), remained unc hanged when injected with BALA, Analysis of BALA content showed that t he wild-type strain had twice the levels found in B and about half of those in the nig mutant, Reversed phase HPLC analysis of catecholamine s in whole-body extracts showed that high levels of N-beta-alanyldopam ine (NBAD) and low levels of dopamine correlated with the 'brown pheno type', whether in the wild-type or the rescued B mutant, Conversely, B mutants contained high concentrations of dopamine, but only minor amo unts of NBAD, The results suggest that B is probably defective in BALA synthesis, because BALA injections resulted in restoring NBAD and dop amine to normal levels similar to those of the wild-type and produced reddish-brown puparial cuticle, However, the nig mutant had high level s of endogenous BALA and dopamine, but low NBAD, and, therefore, appar ently cannot synthesize NBAD, N-Acetyldopamine (NADA) concentrations w ere relatively high in both of the melanic mutants compared to the wil d-type; therefore, NADA, rather than NBAD, may serve as the principal precusor for sclerotizing agents of black puparial cuticle. Copyright (C) 1996 Elsevier Science Ltd