Identification and partial characterization of the major secretory protein of the long hyaline gland in the male grasshopper, Melanoplus sanguinipes

Abstract

In the adult male migratory grasshopper, Melanoplus sanguinipes, the major secretory product of the long hyaline gland (a distinct tubule type of the accessory reproductive gland complex) is an abundant glycoprotein (LHPI) with a native molecular weight of about 72,000 Da. Sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) of this protein gives rise to a 36,000 Da subunit. Partial peptide mapping of the 36,000 Da subunit, using the agents N- chlorosuccinimide , papain, and staphylococcal V8 protease, shows that this polypeptide is found in a viscous secretion and, to a much lesser extent, in empty spermatophores, both of which are recoverable from between the female's ovipositor valves after mating. Polyclonal antibodies raised against the LHPI 36,000 Da subunit electrophoretically purified from long hyaline glands, cross react with similar molecular weight counterparts in viscous secretion and spermatophore extracts. LHPI is present in 1-day-old adults and accumulates up to levels of about 1 mg in 17-day-old virgins. LHPI is the single most abundant protein in the long hyaline gland accounting for 37–51% of the total protein in virgin males 5–17 days old. An estimated 160 μg was lost from the gland in a single mating on day 7 of which 110 μg was recovered at the completion of mating. Mating on day 5, 6, or 7 resulted in a 1.6–1.8 fold increase in rate of in vivo incorporation of [ 3H]leucine into LHPI measured on day 7. This apparent increase in LHPI synthesis is paralleled by increased accumulation of protein in the gland in mated males.