Purification and characterization of an oviposition-stimulating protein ofthe long hyaline tubules in the male migratory grasshopper, Melanoplus sanguinipes

An oviposition-stimulating protein (OSP) was isolated and purified from the long hyaline tubules of the male accessory gland complex in the migratory grasshopper, Melanoplus sanguinipes. Gel filtration of the native OSP, usin g Sephadex G-100, indicates its molecular weight to be about 60 000 Da with the oviposition-stimulating activity while sodium dodecyl sulphate-polyacr ylamide gel electrophoresis shows that the OSP comprises two subunits, each with a molecular weight of 30 000 Da. The purified OSP appears as a single symmetric peak on fast performance Liquid chromatography using Mono Q. Iso electric focusing of the OSP indicates an apparent pi of 5.5. Injection of the OSP induces oviposition in about 70% of ovulated virgin females within 48 h. Stimulation of oviposition can be blocked by a polyclonal antibody ra ised against the OSP 30 000 Da subunits. Amino acid analysis of the dimer a nd its subunits shows a comparatively high content of aspartic acid/asparag ine (14.8%) as well as leucine (12.2%) and glutamic acid/glutamine (12.0%). The N-terminal 21 amino acid sequence of the OSP shows little similarity t o known peptides. Immunoreactivity with the anti-OSP antibody was observed in the viscous secretion, spermatheca, and the egg-pod froth of mated femal es, confirming transfer of the OSP from male to female during copulation. ( C) 1999 Elsevier Science Ltd. All rights reserved.