Identification, RNAi Knockdown, and Functional Analysis of an Ejaculate Protein that Mediates a Postmating, Prezygotic Phenotype in a Cricket

University of Texas Arlington, United States of America
PLoS ONE (Impact Factor: 3.23). 10/2009; 4(10):e7537. DOI: 10.1371/journal.pone.0007537
Source: PubMed


Postmating, prezygotic phenotypes, especially those that underlie reproductive isolation between closely related species, have been a central focus of evolutionary biologists over the past two decades. Such phenotypes are thought to evolve rapidly and be nearly ubiquitous among sexually reproducing eukaryotes where females mate with multiple partners. Because these phenotypes represent interplay between the male ejaculate and female reproductive tract, they are fertile ground for reproductive senescence--as ejaculate composition and female physiology typically change over an individual's life span. Although these phenotypes and their resulting dynamics are important, we have little understanding of the proteins that mediate these phenotypes, particularly for species groups where postmating, prezygotic traits are the primary mechanism of reproductive isolation. Here, we utilize proteomics, RNAi, mating experiments, and the Allonemobius socius complex of crickets, whose members are primarily isolated from one another by postmating, prezygotic phenotypes (including the ability of a male to induce a female to lay eggs), to demonstrate that one of the most abundant ejaculate proteins (a male accessory gland-biased protein similar to a trypsin-like serine protease) decreases in abundance over a male's reproductive lifetime and mediates the induction of egg-laying in females. These findings represent one of the first studies to identify a protein that plays a role in mediating both a postmating, prezygotic isolation pathway and reproductive senescence.

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Article: Identification, RNAi Knockdown, and Functional Analysis of an Ejaculate Protein that Mediates a Postmating, Prezygotic Phenotype in a Cricket

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    • "The role of particular proteins in mediating specific behaviors can be tested experimentally, for example using RNAi technology (Marshall et al. 2009; Rogers et al. 2009; Marshall and DiRienzo 2012), recombinant proteins (Fleming et al. 2009), or enzymatic (Schippers et al. 2006; Rogers et al. 2009) or toxicological (Resende et al. 2013) assays. Recently developed MS-based assays (Aebersold et al. 2013) also offer increasing opportunities for the subsequent quantitative monitoring of individual proteins in large number of individuals (Plumel et al. 2013). "
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    Behavioral Ecology 06/2014; 26(1). DOI:10.1093/beheco/aru096 · 3.18 Impact Factor
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    • "This protein is a trypsin‐like serine protease (Simmons et al. 2013) similar to those reported from the accessory glands of the crickets Gryllus pennsylvannicus (Andrés et al. 2006), Allenemobius socius and A. fasciatus (Marshall et al. 2011). In A. socius RNA interference knockdown has shown that ejaculate serine protease mediates the induction of egg laying in mated females (Marshall et al. 2009). Serine proteases are also involved in sperm function and fertility in invertebrates and vertebrates alike (Green and Summers 1980; Inaba et al. 1993; Kodama et al. 2002). "
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    Evolution & Development 03/2014; 16(2):101-9. DOI:10.1111/ede.12068 · 2.72 Impact Factor
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    • "RNAi knockdown of ejac-sp in male crickets led to reduced levels of the protein in the ejaculate, which correlated with reduced numbers of eggs laid by females mated to these males. ejac-sp is also a candidate speciation gene, as it shows a high level of divergence due to positive selection between two related cricket species (Marshall et al., 2009, 2011). In D. melanogaster, a predicted trypsin-like serine protease in the seminal fluid, seminase (CG10586), is also required for normal induction of egg-laying in mated females (LaFlamme et al., 2012). "
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