Site of synthesis of the haemolymph agglutinin of Melanoplus differentialis (Acrididae: Orthoptera)

Abstract

Several species of Melanoplus grasshoppers contain a haemolymph agglutinin exhibiting both d-galactosidic and d-glucosidic binding specificities. With the exception of the flesh fly Sarcophaga peregrina, the site(s) of synthesis of insect agglutinins is uncertain. Primary cultures of M. differentialis fat body, haemocytes, ovary and testes were established. An ELISA assay demonstrated that the fat body, ovary and testes tissues released significant amounts of agglutinin into the culture medium over a 4-day period. Immunoprecipitated agglutinin from the culture medium was radiolabelled when the cultures were metabolically labelled with [35S] methionine. Haemocyte culture medium and cell lysates of the 4 tissues did not contain detectable amounts of radiolabelled agglutinin. Attempts to alter the kinetics of agglutinin release from fat body cultures through addition of microbial cell wall components (lipopolysaccharide, peptidoglycan, zymosan, or laminarin) were unsuccessful.