Temporal expression profile of an accessory-gland protein that is transferred via the seminal fluid of the simultaneous hermaphrodite Lymnaea stagnalis

Riccardo R Filangieri,Joris M Koene,Dick Roelofs,Isabelle B C Van Der Ouderaa,Angus Davison,Janine Mariën,Daniel J Jackson,Elferra M Swart,Jacintha Ellers

doi:10.1093/mollus/eyz005

Abstract

Male accessory-gland proteins are known to affect female physiology in multiple ways, maximizing a male’s reproductive success—often at a cost to the female. Due to this inherent sexual conflict, accessory gland proteins (ACPs) are generally studied in separate-sex organisms. While ACPs have also been identified in simultaneous hermaphrodites as an important part of post-copulatory sexual selection processes, their study has lagged behind that of ACPs in organisms with separate sexes. In the great pond snail, Lymnaea stagnalis, an ACP affecting egg laying, ovipostatin, is produced in the prostate gland. Based on the published partial Ovipostatin gene sequence, we now provide the complete mRNA and gene sequences, and confirm that gene expression is prostate gland-specific. More importantly we observed a significant increase in Ovipostatin expression in sperm donors after ejaculation. Ovipostatin gene expression did not differ between donors giving their ejaculate first (primary donors) and those donating an ejaculate after having been inseminated (secondary donors). These observations support a role for ovipostatin in reproduction and highlight the importance of standardizing the time point when measuring expression levels of ACPs.

Highlights

In species that reproduce by internal fertilization, males transfer complex ejaculates into females, delivering sperm in fluid containing a cocktail of proteins (Birkhead, Hosken & Pitnick, 2008)
For quantitative PCR, we developed a primer set based on Exon 4 from the Ovipostatin mRNA
The Ovipostatin gene is composed of five exons, respectively 117, 55, 81, 135 and 128 bp long, and four introns, respectively 139, 2,659, 780 and 526 bp long (Fig. 1A)

Summary

Introduction

In species that reproduce by internal fertilization, males transfer complex ejaculates into females, delivering sperm in fluid containing a cocktail of proteins (Birkhead, Hosken & Pitnick, 2008). ACPs have been shown to affect female physiology, behaviour, immunity and life history (Perry, Sirot & Wigby, 2013). Males achieve these changes either by inducing oviposition (Hirata, 1981; Chapman et al, 1995), decreasing female sexual receptivity after copulation (i.e. latency to copulate, Wolfner, 1997), or inhibiting other males from accessing female gametes (i.e. mating plug formation, Wigby & Chapman, 2005; Avila et al, 2010), thereby facilitating sperm storage (Tram and Wolfner, 1999; Wigby et al, 2009; Zizzari, Smolders & Koene, 2014). It has been argued that ACPs are a key evolutionary driving force for hermaphrodites and form an important part of postcopulatory sexual-selection processes (Nakadera & Koene, 2013; Ramm, 2017)

Methods

Results

Conclusion