Meeting Abstract
Bark scorpions (Centruroides spp.) are a large group of 40+ species in the family Buthidae whose center of distribution is west-central Mexico. Some species represent the most lethal scorpions known, causing ~ 1000 human deaths per year. It is not surprising that venoms of the most toxic members of this genus have been well characterized. Surprisingly little is known, however, regarding the ecology and evolution of their toxins. An ultimate explanation for the dramatic differences in toxicity observed across species, for example, has never been attempted. There are interesting intraspecific differences as well. The striped bark scorpion (C. vittatus) of New Mexico exhibits sexual dimorphism, with the tails (metasomas) of males being significantly longer and thinner than females. Males also sprint significantly faster, but are significantly less likely to sting when threatened by a simulated predator. Why? Venom is metabolically costly, and these costs may be different for males and females. Perhaps males have fewer feeding opportunities, a different suite of prey, or need to reserve their venom for the stings they deliver to females during courtship. Such hypotheses predict there might be gender differences in the composition and function of venoms. We here report our preliminary results. HPLC analyses suggest differences in both specific venom constituents and their concentrations. Proteomic and transcriptomic analyses of the venom glands are underway. And while we have yet to examine gender differences in toxicity, male venom is significantly more painful than female venom, as revealed using a paw-licking assay with domestic mice.
