Identification of novel ejaculate proteins in a seed beetle and division of labour across male accessory reproductive glands. (January 2019)

• Record Type: Journal Article
• Authors: Bayram, Helen; Sayadi, Ahmed; Immonen, Elina; Arnqvist, Göran
• Is Part Of: Insect biochemistry and molecular biology. Volume 104(2019)
• Page Start: 50
• Page End: 57
• Publication Date: 2019-01
• Subjects: Reproductive proteins -- Stable isotope labelling -- Acps -- Sperm competition -- Seminal fluid; Insect biochemistry -- Periodicals; Insects -- Physiology -- Periodicals; Insects -- Molecular aspects -- Periodicals; Biochemistry -- Periodicals; Insectes -- Biochimie -- Périodiques; Insectes -- Composition -- Périodiques; Insectes -- Physiologie -- Périodiques; Insectes -- Aspect moléculaire -- Périodiques; Biochimie -- Périodiques; Biochemistry; Insect biochemistry; Insects -- Molecular aspects; Insects -- Physiology; Periodicals; 572.8157
• DOI: 10.1016/j.ibmb.2018.12.002
• Languages: English
• ISSNs: 0965-1748

Abstract

Abstract: The male ejaculate contains a multitude of seminal fluid proteins (SFPs), many of which are key reproductive molecules, as well as sperm. However, the identification of SFPs is notoriously difficult and a detailed understanding of this complex phenotype has only been achieved in a few model species. We employed a recently developed proteomic method involving whole-organism stable isotope labelling coupled with proteomic and transcriptomic analyses to characterize ejaculate proteins in the seed beetle Callosobruchus maculatus . We identified 317 proteins that were transferred to females at mating, and a great majority of these showed signals of secretion and were highly male-biased in expression in the abdomen. These male-derived proteins were enriched with proteins involved in general metabolic and catabolic processes but also with proteolytic enzymes and proteins involved in protection against oxidative stress. Thirty-seven proteins showed significant homology with SFPs previously identified in other insects. However, no less than 92 C. maculatus ejaculate proteins were entirely novel, receiving no significant blast hits and lacking homologs in extant data bases, consistent with a rapid and divergent evolution of SFPs. We used 3D micro-tomography in conjunction with proteomic methods to identify 5 distinct pairs of male accessory reproductive glands and to show that certain ejaculate proteins were only recovered in certain male glands. Finally, we provide a tentative list of 231 candidate female-derived reproductive proteins, some of which are likely important in ejaculate processing and/or sperm storage. Graphical abstract: Image 1 Highlights: Male ejaculate proteins are diverse and rapidly evolving reproductive proteins but their identification is challenging. We use a proteomic method based on whole-organism stable isotope labelling and tandem mass spectrometry. We identified 317 male derived proteins, of which 92 are novel proteins, and 231 candidate female reproductive proteins. 3D micro-tomography unveiled 5 distinct pairs of male accessory reproductive glands. Some proteins were recovered only in some glands, suggesting substantial differentiation across male glands.