The biosynthesis, function and fate of taurine during the metamorphosis of the noctuid moth Mamestra configurata Wlk.

Abstract

Taurine is only a minor constituent of growing larvae and prepupae of Mamestra configurata. Following pupation there is a massive synthesis and accumulation of taurine in the pupa. Radioisotope experiments with [ 35S]-cysteine demonstrated that labelled cysteamine, hypotaurine and taurine were formed rapidly following the injection of labelled cysteine into two-day-old pupae. No radioactivity was found in either cysteine sulphinic acid or cysteic acid. The biosynthesis of taurine from cysteine in the pupa appears to be via: cysteine → cysteamine → hypotaurine → taurine. Newly-synthesized taurine was liberated into pupal blood and initially accumulated there. Most of the taurine in the blood of the non-diapausing pupae was taken up by developing adult structures, and especially by the flight muscles. More than 90% of the taurine synthesized during metamorphosis was found in the thorax of the adult moth, indicating an important role for taurine in the flight muscles. Diapause-programmed individuals also synthesized and accumulated large amounts of taurine following pupation. Taurine was stored in the blood of the diapausing pupa for later use when development resumed. Diapause-related functions for taurine may include membrane stabilization and diapause maintenance.