title: Glutathione biosynthesis in the aging adult yellow-fever mosquito [Aedes aegypti (Louisville)].
abstract: Our previous findings [Hazelton & Lang (1978) Fed. Proc. Fed. Am. Soc. Exp. Biol. 37(6), 2378 (abstr.)] demonstrated a senescence-specific decrease in glutathione (GSH) concentration in the yellow-fever mosquito Aedes aegypti (Louisville)]. As a possible mechanism for this change, GSH biosynthesis was investigated in adult mosquitoes of different ages through the life-span. Biosynthesis was measured as the incorporation rate of [14C]glycine or [14C]cystine into glutathione. Essential information to validate the procedure was also obtained on the precursor-amino-acid pool sizes and kinetic parameters such as lag-time and time course of incorporation. Also, synthesis de novo rather than exchange was verified using buthionine sulphoximine, a specific inhibitor of GSH biosynthesis. The synthetic rates with either amino acid precursor varied throughout the adult life-span, but the patterns for both precursors were essentially identical. Biosynthesis was high in the newly emerged adult and decreased 62-70% (P less than 0.005) to a plateau during maturity. From the mature value there was a decrease of 36-41% (P less than 0.005) to a new plateau during senescence. Glutathione biosynthesis and concentration were correlated throughout maturity and senescence (r = 0.982) and thus biosynthesis was proportional to glutathione content. On this basis we concluded that impaired biosynthesis is the major and perhaps sole mechanism for the aging decrease in glutathione content.
mesh_terms: D000330:Aedes / Q000254:growth & development / Q000378:metabolism*; D000375:Aging; D000596:Amino Acids / Q000378:metabolism; D000818:Animals; D003553:Cystine / Q000378:metabolism; D005260:Female; D005978:Glutathione / Q000096:biosynthesis*; D005998:Glycine / Q000378:metabolism; D007700:Kinetics; D013997:Time Factors
chemical_list: D000596:Amino Acids; D003553:Cystine; D005978:Glutathione; D005998:Glycine