L-thyroxine (T4) elevates the free amino acid pool of haemolymph plasma of tasar silkworm, Antheraea mylitta drury (Lepidoptera: Saturniidae).

Abstract

Concentration of free amino acids (FAA) in the haemolymph plasma of male and female tasar silkworm, A. mylitta, during fifth larval instar were determined by amino acid analyzer after administration of vertebrate thyroxine (T4). Twenty FAA have been identified in haemolymph plasma in both sexes, out of which ten were found to be predominating. Treatment with anabolic doses of thyroxine (0.5 and 1.0 micrograms/g) were able to enhance the titre of all the individual FAA which has been also reflected in the total concentrations. A specific pattern of variations in plasma FAA recorded during 5th larval instar, was not altered by the administered thyroxine. Our results thus indicate that T4 has a controlling influence on the FAA profiles of silkworm as observed in other biochemical parameters of the insect.