Amino acid nitrogen and proteins in the haemolymph of adult desert locusts, Schistocerca gregaria

Abstract

The changes in amino acid nitrogen, proline, and protein content in the haemolymph of adult desert locusts were followed up to 60 days from the time of adult emergence. Large amounts of amino acid nitrogen are present in young insects. The highest concentration was observed on the second day in both sexes and a gradual decline was noticed after 8 days. Proline content in haemolymph followed almost a similar pattern to amino acid nitrogen. Protein levels declined during the first 3 days, increased rapidly up to 15 days, and remained more or less constant thereafter in both sexes. The possible significance of these observations is discussed. A maximum of twelve and ten protein bands was observed in female and male haemolymph samples by polyacrylamide gel electrophoresis. The electrophoretic patterns became more or less similar after a week's time after final ecdysis and consisted of at least ten protein bands in female and eight in male electropherograms. Gel chromatography on Sephadex G-150 column resolved the mixture of haemolymph proteins of male and female locusts 3 to 7 days old into three main fractions. The presence of sex specific, vitellogenic proteins, and human serum albumin-like proteins was detected. By electrogel chromatographic techniques at least 26 haemolymph proteins were found in females and 21 in males. Approximate molecular weights, diffusion constants, and Stoke's radii of all the 47 haemolymph proteins are reported for the first time.