Male reproductive proteins (sperm, seminal fluid proteins [SFPs]) are fascinating traits. Since sperm is essential for reproduction, most sperm proteins are expected to be under strong purifying selection. Yet, sperm is the most diverse cell type known (Pitnick et al. 2009, Sperm Biology). Moreover, recent studies are revealing that SFPs are under strong and diversifying selective pressures. For example, in primates a positive correlation between the evolutionary rate of one SFP gene and the strength of sperm competition has been reported (Dorus et al. 2004). Given their strong and divergence selective pressures, the research of male reproductive proteins is expected to expand the general understanding of evolutionary processes.
Male reproductive proteins of freshwater snail species offer excellent research opportunities, and their systematic and in-depth examination has just started. First, these snails are simultaneous hermaphrodites (i.e. having male and female functions in a single body). The difference in reproductive mode contrasts with common model species, and it allows us to test whether the insights from previous studies are applicable to hermaphrodites. Our research in hermaphrodites might provide unique insights into the evolutionary processes of male reproductive proteins. Second, reproductive modes of these freshwater snails have been relatively well-documented. Based on this knowledge, we can make predictions about how male reproductive proteins have evolved in each lineage. Especially in this project, we use accumulated genomic and transcriptomic databases of Lymnaea stagnalis, in order to identify candidate sperm- and SFP-related genes. We further utilize bioinformatic tools to identify their potential biological functions. Furthermore, we explore if these candidate genes are conserved or diversified across freshwater snail species, by identifying these genes in different freshwater snail species.
– Transcriptomics / proteomics
– Molecular evolutionary analyses
(Note that the approaches will change depending on the status of on-going projects. For the details, please contact the supervisors.)
Sexual selection, molecular evolution, informatics, omics, big data, next generation sequencing, freshwater snail, hermaphroditism, selfing
Dorus S, Evans PD, Wyckoff GJ, Choi SS, Lahn BT. 2004. Rate of molecular evolution of the seminal protein gene SEMG2 correlates with levels of female promiscuity. Nat Genet. 36:1326–9.
Pitnick S, Wolfner MF, Suarez S. 2009. Ejaculate–female and sperm– female interactions. Sperm Biology. 247-304.
Dr. Joris M. Koene
Dr. Yumi Nakadera