Abstract
Molecules that mediate reproductive interactions are some of the most rapidly evolving traits. Researchers have often suggested that this is due to coevolution at key physiological interfaces. However, very few of these interfaces are well understood at the functional level. One such interface is the digestion of the spermatophore in Lepidoptera. Female Lepidoptera have a specialized reproductive organ called the bursa copulatrix that receives and processes the male spermatophore, a complex proteinaceous ejaculate. In the cabbage white butterfly, Pieris rapae, the bursa secretes a mixture of proteases hypothesized to digest the spermatophore. However, these proteases remain biochemically uncharacterized. Using a zymogram approach, we identified six proteases in bursal extracts at sufficiently high concentrations to characterize their in vitro activity. We assessed the modes of action of these bursal enzymes by quantifying their activity following exposure to diagnostic protease inhibitors. A serine protease-specific inhibitor failed to reduce bursal protease digestion of casein. However, a cysteine protease-specific inhibitor did decrease the activity of some proteases. To explore the possible molecular mechanisms responsible for these responses, we created protease homology models. The models mirrored the results of our in vitro experiments, indicating that protease homology models may offer insight into underlying functional mechanisms. Whether the observed bursal protease resistance to known inhibitors is important in the context of spermatophore digestion remains to be tested. However, our results suggest the exciting possibility that bursal protease specificity may have evolved in response to interactions with various proteins and inhibitors present within the female tract during the reproductive process.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.