Stomachs in your butterfly : exploring the identity and activity of proteases in the reproductive tract of female butterflies.

Reproductive traits are some of the most rapidly evolving traits in the natural world. However, research to date has focused heavily on male reproductive traits such as male genitalia, leaving female reproductive traits understudied. As a result, we know little about female reproductive adaptations or how they may have co-evolved with male reproductive traits. Butterflies provide an excellent system to study reproductive interactions and physiology from the female perspective. Female butterflies have a specialized reproductive organ called the bursa copulatrix that appears to be co-evolving with specific male traits. The bursa accepts and actively digests the complex male ejaculate, called the spermatophore. Our research focused on the proteases present in the bursa of the Cabbage White butterfly, Pieris rapae. Using a general colorimetric assay, we discovered high levels of overall protein digestion within the bursa. Using transcriptomic and proteomic approaches, we identified nine putative proteases from two main functional classes that may play a role in bursal digestion of the spermatophore. Using a zymogram approach, we conducted an in vitro protein digestion assay to measure the activity of specific bursal proteases. Finally, we investigated functionality of each protease by disrupting specific modes of protease action using targeted protease inhibitors and quantifying subsequent loss of activity. Our findings offer new insights into female bursal adaptations, and provide groundwork for future studies of co-evolution between the bursa and spermatophore

Reproductive interaction in the cabbage white butterfly: conflict or cooperation?

Reproductive interaction in the cabbage white butterfly: conflict or cooperation?. Undergraduate students symposiu

Characterizing proteins involved in a post-copulatory interaction in the cabbage white butterfly

Characterizing proteins involved in a post-copulatory interaction in the cabbage white butterfly. Science 201

Structural, biochemical, and evolutionary characterization of a butterfly ejaculate

Structural, biochemical, and evolutionary characterization of a butterfly ejaculate. Evolutio

Sexual cooperation and conflict in butterfly spermatophore proteins

Sexual cooperation and conflict in butterfly spermatophore proteins. Evolutio

Molecular dynamics and phenotypic divergence in a post-copulatory interaction in the butterfly Pieris rapae

Molecular dynamics and phenotypic divergence in a post-copulatory interaction in the butterfly Pieris rapae. Evolutio

Correction for Meslin et al., Structural complexity and molecular heterogeneity of a butterfly ejaculate reflect a complex history of selection

International audienc

Structural complexity and molecular heterogeneity of a butterfly ejaculate reflect a complex history of selection

Male ejaculates are often structurally complex, and this complexity is likely to influence key reproductive interactions between males and females. However, despite its potential evolutionary significance, the molecular underpinnings of ejaculate structural complexity have received little empirical attention. To address this knowledge gap, we sought to understand the biochemical and functional properties of the structurally complex ejaculates of Pieris rapae butterflies. Males in this species produce large ejaculates called spermatophores composed of an outer envelope, an inner matrix, and a bolus of sperm. Females are thought to benefit from the nutrition contained in the soluble inner matrix through increases in longevity and fecundity. However, the indigestible outer envelope of the spermatophore delays female remating, allowing males to monopolize paternity for longer. Here, we show that these two nonsperm-containing spermatophore regions, the inner matrix and the outer envelope, differ in their protein composition and functional properties. We also reveal how these divergent protein mixtures are separately stored in the male reproductive tract and sequentially transferred to the female reproductive tract during spermatophore assembly. Intriguingly, we discovered large quantities of female-derived proteases in both spermatophore regions shortly after mating, which may contribute to spermatophore digestion and hence, female control over remating rate. Finally, we report evidence of past selection on these spermatophore proteins and female proteases, indicating a complex evolutionary history. Our findings illustrate how structural complexity of ejaculates may allow functionally and/or spatially associated suites of proteins to respond rapidly to divergent selective pressures, such as sexual conflict or reproductive cooperation