Dr. James Biardi

Research in Environmental Toxicology

Resistance to snake venoms has been described in several reptile and mammal species, but there has been little work on its ecological and evolutionary context. It is clear that resistance and toxicity provide an excellent system for studying a myriad of questions about adaptive variation and co-evolution at the molecular level. Since we already know much about their natural history, population structure and behavior, California ground squirrels (Spermophilus beechey) provide a useful natural experimental context for exploring the effects of evolutionary history and ecological context on defenses to venomous predators. Investigations of multiple species in a prey community can reveal new information about the distribution of resistance and its taxonomic and ecological correlates. I believe that exploring the structure and function of venom toxins and inhibitors in a comparative context can uncover new knowledge that will be equally intriguing to those interested in evolutionary biology, biochemistry, and ecology.

Research projects flow along two main lines of investigation:

1. What is the natural context of prey resistance and venom toxicity? What is the range of variation in venom resistance within and between prey species? What are the relevant ecological (i.e. body size, predation density, predator identity) and evolutionary (i.e. phylogeny, or duration and intensity of predation over time) correlates of resistance in vertebrate prey of venomous snakes? Are differences in the sequence, structure, and/or activity of venom metalloproteases from northern Pacific rattlesnakes coevolving with prey resistance?

2. What is the molecular basis of resistance? What is the underlying genetic basis of prey resistance factors? What is the relationship between changes in amino acid sequence and function in prey inhibitors? What systems are involved in the capacity of prey to survive other venom toxins, such as venom phospholipases (PLA2s) that can disrupt cell integrity, or kallikrein-like toxins that disrupt hemostasis? What is the effectiveness and specificity of resistance factors against MMPs relevant to human disease states? Do natural mammalian resistance factors provide a useful resource for new therapeutic approaches?

Courses Taught:

• BI 76 Environmental Science
• BI 170 & 172 General Biology (majors)
• BI 375 Biochemical Ecology
• CH 11 Inorganic Chemistry Lab

Publications:

Biardi, J.E. (in press). The ecological and evolutionary context of mammalian resistance to pitviper venoms. Biology of the Rattlesnakes Symposium Volume.

Biardi, J.E., D.C. Chien*, and R.G. Coss (in press). California ground squirrel (Spermophilus beecheyi) inhibition of rattlesnake venom digestive and hemostatic toxins. Journal of Chemical Ecology.

Biardi, J.E., R.G. Coss, and D.G. Smith (2000). California ground squirrel (Spermophilus beecheyi) blood sera inhibits crotalid venom proteolytic activity. Toxicon 38:713-721.

Coss, R.G. and J.E. Biardi (1997). Individual variation in the antisnake behavior of California ground squirrels (Spermophilus beecheyi). Journal of Mammalogy 73:294-310.

Hornberger, J.H., J.E. Biardi, and D.H. Owings (1997). A call for integration: A review of and response to Behavioral Mechanisms in Evolutionary Ecology (L. Real, ed.) Behavioral Processes 41:108-115.

Hanley, K.A., J. E. Biardi, C.M. Greene, T.M. Markowitz, C.E. O'Connell, and J.H. Hornberger (1996). The behavioral ecology of host-parasite interactions: An interdisciplinary challenge. Parasitology Today 12:371-373.

Kohn, J.R. and J.E. Biardi (1995). Outcorssing rates and inferred levels of inbreeding depression in gynodioecious Cucurbita foetidissima (Cucurbitaceae). Heredity 75:77-83.

Smith, F., B. Bestelmeyer, J.E. Biardi, M. Strong (1993). Anthropogenic extinction of the endemic woodrat Neotoma bunkeri from Isla Coronado, Baja California, Mexico. Biodiversity Letters 1:149-155.