RESISTANCE TO RATTLESNAKE VENOMS IN AN EASTERN COLORADO RODENT COMMUNITY

The grasslands of eastern Colorado are inhabited by two species of rattlesnakes, the Prairie Rattlesnake (Crotalus viridis) and the Desert Massasauga Rattlesnake (Sistrurus tergeminus edwardsii). An array of rodent species, both native and introduced, also occupy these grasslands, and serve as a varied prey base for the previously listed rattlesnakes. Predator-prey interactions in this system gain an additional level of complexity due to the presence of venoms, a chemical arsenal possessed by both rattlesnakes to incapacitate their prey. Rodents in other systems have demonstrated resistance to snake venoms, and there is potential for a similar dynamic to be present in eastern Colorado. This project aimed to characterize resistance to Prairie Rattlesnake and Desert Massasauga Rattlesnake venoms in a suite of wild rodents, using two field sites to better understand the role of co-occurrence of predator-prey partners. Resistance to venoms was explored using in-vivo techniques (LD50 assays on test populations of wild-collected rodents) and in-vitro assays (serum metalloprotease inhibition). Rodent serum was further analyzed using affinity chromatography to isolate potential venom-resistance proteins. Results provide a community-level view of venom resistance and indicate that resistance to venoms is variable across predator-prey species pairings. Additionally, this study characterized the diet of the Prairie Rattlesnake, a taxon for which little dietary data has been collected. The Prairie Rattlesnake occupies a broad latitudinal distribution, spanning a climatic gradient, and is believed to be a dietary generalist. We analyzed prey remains from preserved museum specimens and compiled a list of prey items consumed. This dataset was further used to detect feeding variation as a result of latitude, ontogeny, and seasonality. No apparent feeding differences occurred as a result of latitude, a strong signature of dietary ontogeny was absent in the dataset, and snakes did not exhibit prolonged foraging in warmer regions. These studies elucidate the trophic biology of snakes on their ecosystems, an area of study that at present remains poorly understood. Results indicate that rattlesnakes have the potential to exert tremendous selective pressures upon the prey communities they interact with, and thus may impact prey species over evolutionary timescales. Understanding the underpinnings of snake foraging and resistance to snake venoms allows us to contextualize better the role of snakes in natural systems

High Pressure Insulator-Metal Transition in Molecular Fluid Oxygen

We report the first experimental evidence for a metallic phase in fluid molecular oxygen. Our electrical conductivity measurements of fluid oxygen under dynamic quasi-isentropic compression show that a non-metal/metal transition occurs at 3.4 fold compression, 4500 K and 1.2 Mbar. We discuss the main features of the electrical conductivity dependence on density and temperature and give an interpretation of the nature of the electrical transport mechanisms in fluid oxygen at these extreme conditions.Comment: RevTeX, 4 figure

Group Brainstorming Field Study: Effect of Size, Recording Method, and Task, on Productivity and Participants' Reactions.

This field experiment in brainstorming was formulated to test Osborn's brainstorming technique using his directives. Three variables were studied in a 2 x 3 x 2 factorial analysis for the effect of group size, method of recording ideas, and group task upon group productivity and participants' reactions to the experience. Small groups (5-7) and large groups (9-19) were tested using three methods for recording ideas contributed: board (ideas listed on board, visible to the participants); secretary (ideas compiled on notepad, not visible to participants); and , oral (ideas taperecorded). Two tasks were used: contrived (How many ways can you find to use the Pringle Potato Chip container?); and , real (formulated to generate ideas as alternatives for a problem identified by the group). The same leader was used for all experiments. Groups were given identical instructions and were led through the session using the hitch-hiking and idea-spurring suggestions as per Osborn's directives. The fifteen minute brainstorming sessions were divided into thirds to identify the most productive time component. Subjects were existing groups who met to solve one of their own problems during a regularly scheduled meeting of their group. The significant findings were: (1) Participants in small groups contributed a greater mean number of ideas per person than did participants in large groups. (2) Although all participants were satisfied with their involvement and with their own participation, responses from the small groups indicated a greater satisfaction. (3) Participants in the board method indicated greater satisfaction with their productivity than did participants in the secretary or oral methods. (4) The real task was significantly more meaningful to participants than the contrived task. (5) All groups contributed more ideas in the first five minutes of the fifteen minute brainstorming sessions.Ph.D.CommunicationUniversity of Michiganhttp://deepblue.lib.umich.edu/bitstream/2027.42/157696/1/8017218.pd

I. High Pressure - High Temperature Electronic Spectra. Ii. Electricalresistance at High Pressure

154 p.Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 1961.U of I OnlyRestricted to the U of I community idenfinitely during batch ingest of legacy ETD

Crotalus pricei (Twin-spotted Rattlesnake) and Crotalus transversus (Cross-banded Mountain Rattlesnake). Reverse Crypsis Behavior

This video demonstrates behavior. Most videos in this collection have no audible language and for those that do, the language isn't necessary to understand the behavior. For that reason, transcripts are not provided.Integrative Biolog