title: Functional characterizations of venom phenotypes in the eastern diamondback rattlesnake (Crotalus adamanteus) and evidence for expression-driven divergence in toxic activities among populations.
abstract: Phenotypes frequently vary across and within species. The connection between specific phenotypic effects and function, however, is less understood despite being essential to our understanding of the adaptive process. Snake venoms are ideal for identifying functionally important phenotypic variation because venom variation is common, and venoms can be functionally characterized through simple assays and toxicity measurements. Previous work with the eastern diamondback rattlesnake (Crotalus adamanteus) used multivariate statistical approaches to identify six unique venom phenotypes. We functionally characterized hemolytic, gelatinase, fibrinogenolytic, and coagulant activity for all six phenotypes, as well as one additional venom, to determine if the statistically significant differences in toxin expression levels previously documented corresponded to differences in venom activity. In general, statistical differences in toxin expression predicted the identified functional differences, or lack thereof, in toxic activity, demonstrating that the statistical approach used to characterize C. adamanteus venoms was a fair representation of biologically meaningful differences. Minor differences in activity not accounted for by the statistical model may be the result of amino-acid differences and/or post-translational modifications, but overall we were able to link variation in protein expression levels to variation in function as predicted by multivariate statistical approaches.
authors.affiliation: Department of Biological Science, Florida State University, Tallahassee, FL 32306-4295, USA.
authors.forename: Mark J
authors.initials: MJ
authors.lastname: Margres
authors.affiliation: National Natural Toxins Research Center (NNTRC), Texas A&M University-Kingsville, MSC 158, 975 West Avenue B, Kingsville, TX 78363, USA.
authors.forename: Robert
authors.initials: R
authors.lastname: Walls
authors.affiliation: National Natural Toxins Research Center (NNTRC), Texas A&M University-Kingsville, MSC 158, 975 West Avenue B, Kingsville, TX 78363, USA.
authors.forename: Montamas
authors.initials: M
authors.lastname: Suntravat
authors.affiliation: National Natural Toxins Research Center (NNTRC), Texas A&M University-Kingsville, MSC 158, 975 West Avenue B, Kingsville, TX 78363, USA.
authors.forename: Sara
authors.initials: S
authors.lastname: Lucena
authors.affiliation: National Natural Toxins Research Center (NNTRC), Texas A&M University-Kingsville, MSC 158, 975 West Avenue B, Kingsville, TX 78363, USA; Department of Chemistry, Texas A&M University-Kingsville, MSC 161, Kingsville, TX 78363, USA.
authors.forename: Elda E
authors.initials: EE
authors.lastname: Sánchez
authors.affiliation: Department of Biological Science, Florida State University, Tallahassee, FL 32306-4295, USA. Electronic address: drokyta@bio.fsu.edu.
authors.forename: Darin R
authors.initials: DR
authors.lastname: Rokyta
mesh_terms: D000818:Animals; D002851:Chromatography, High Pressure Liquid; D003435:Crotalid Venoms / Q000737:chemistry / Q000633:toxicity*; D017839:Crotalus; D004591:Electrophoresis, Polyacrylamide Gel; D006461:Hemolysis / Q000187:drug effects
chemical_list: D003435:Crotalid Venoms
keywords: Expression variation; Toxic activities; Venom