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

Department of Entomology, Kansas State University, Manhattan, Kansas, United States of America.
PLoS ONE (Impact Factor: 3.53). 10/2009; 4(10):e7537. DOI: 10.1371/journal.pone.0007537
Source: PubMed

ABSTRACT 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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    Insect biochemistry and molecular biology 08/2014; DOI:10.1016/j.ibmb.2014.05.005 · 3.42 Impact Factor
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    ABSTRACT: Nuptial feeding, although common in the insect world, varies greatly in its form and function. Here, we test the function of the hemolymph nuptial gift in the southern ground cricket, Allonemobius socius, and attempt to determine if it functions as parental investment or mating effort. We manipulated the number of gifts a female received during courtship (one vs. none). We also recorded other aspect of courtship, such as feeding duration and spermatophore attachment duration. Female fecundity was measured for 7 d post-mating. Our results indicate that female egg laying is significantly higher when a gift is provided, but the increase in egg laying is not related to gift size. In addition, the lack of a gift does not affect the male's ability to transfer a spermatophore. Together, these data suggest that the nuptial gift acts as parental investment and not as mating effort.
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