Structural spermatophore proteins and a trypsin‐like enzyme from the accessory reproductive glands of the male grasshopper,Melanoplus sanguinipes

Abstract

AbstractSome of the major structural spermatophore proteins and a trypsin‐like enzyme have been identified from the accessory reproductive glands of the male migratory grasshopper,Melanoplus sanguinipes.Polyclonal antibodies raised against the purified major soluble spermatophore protein (SP62) of M, 62,000 were used in Western blots to identify a soluble Mr85,000 putative precursor protein and, by immunohistochemistry and by partial proteolysis with staphylococcal V8 protease followed by Western blotting, an insoluble putative precursor protein from short hyaline gland three (SH3). The protein SP62 was formed in vitro by the incubation of crude homogenates of accessory gland tissues, seemingly by an interaction between SH3 secretion and soluble proteins from the remainder of the gland complex. In addition to the immunological similarity between SH3 secretion and SP62, there was also a strong similarity between the amino acid compositions of SH3 secretion and sodium dodecyl sulfate (SDS)‐extracted spermatophores. A family of white gland proteins (designated A‐group white gland proteins; WGPA) that showed intermale and intergland variations were also structural spermatophore proteins. Reserves of the major Mr22,000 and 21,000 forms declined by about 24 μg at mating. Polyclonal antibodies raised against these Mrforms recognized an additional Mr28,200 form in white glands one to three and a Mr9,600 counterpart in white gland four. WGPA‐immunoreactive proteins were evidently incorporated into the spermatophore as insoluble products. Both WGPA and SP62 antigens were localized chiefly in the outermost layers of the spermatophore but also occurred in the inner core. Crude homogenates of accessory glands hydrolyzed three trypsin substrates and an aminopeptidase substrate. The role that these enzymes might play in spermatophore formation is discussed.