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Utilization of [ 14 C]phenylalanine derived from arylphorin or free amino acid in Manduca sexta pharate adults
Author(s) -
Wu Min,
Tischler Marc E.
Publication year - 1995
Publication title -
archives of insect biochemistry and physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.576
H-Index - 66
eISSN - 1520-6327
pISSN - 0739-4462
DOI - 10.1002/arch.940280307
Subject(s) - phenylalanine , manduca sexta , biology , hemolymph , biochemistry , cuticle (hair) , amino acid , sphingidae , metabolism , food science , botany , larva , anatomy
Abstract The role of arylphorin as a storage protein was studied using 14 C‐arylphorin. 14 C‐arylphorin was produced optimally by incubating one‐half fat body from Manduca sexta fifth instar larvae at 22°C for 24 h, in 1 ml of medium containing amino acids at 25% of their physiological concentration with [U‐ 14 C]‐phenylalanine (phe) provided initially without nonlabeled phenylalanine. Nonlabeled phe was provided after 1 h at 16% of its physiological concentration. The specific activity of 14 C‐arylphorin produced in vitro was 30 times greater than that generated in vivo. Injection of 14 C‐arylphorin into pharate adults was used to study the distribution of 14 C‐phe derived from this protein into 14 CO 2 and tissues for comparison with injection of free 14 C‐phe during the middle (days 6 to 12 pharate adult) and late (days 12 to 17 pharate adult) stages of adult development. Appearance of 14 CO 2 from 14 C‐arylphorin as compared to 14 C‐phenylalanine showed a slower time course during both the middle and late stages of development, in keeping with the time needed for degradation of the protein. In accord with faster phe turnover near the end of adult development, total 14 CO 2 production was greater and the retention of 14 C in hemolymph and fat body was less compared to the middle stage of development regardless of whether 14 C‐arylphorin or 14 C‐phe was injected. In the middle stage of development, the appearance of 14 C in the cuticle and head parts was greater, whereas incorporation into abdomen and thorax was less than during the late stage of development. Since the pattern of 14 C distribution from 14 C‐arylphorin and 14 C‐phe was similar, one major function of arylphorin must be as a storage protein replenishing the supply of free amino acids used for synthesis of adult tissues. These results also suggest a limited contribution of M. sexta arylphorin to formation of the cuticle subsequent to day‐6 pharate adult. © 1995 Wiley‐Liss, Inc.