Dan Preston tracks cold-blooded animals across the globe
By Lee Sherman
Dan Preston pauses outside an ordinary-looking door in Cordley Hall. "Most people who walk by have no idea what's inside this room," the OSU biology major remarks as he turns the knob. Entering the vault-like foyer outside two environmentally controlled chambers, he unlocks one of the gleaming white enamel doors and steps through.
"Here," he says, "is where we keep the garter snakes." From dozens of glass tanks, reptilian eyes look out from beneath mounds of fluffy, cellulose-based bedding and upside-down egg-carton shelters. "These guys are from Manitoba, so we keep it cool for them during the winter."
Under the supervision of OSU zoology professor Robert Mason and veterinary medicine professor Craig Mosley, Preston is studying anesthetics in reptiles for his Honors College senior thesis. These red-sided garter snakes from Manitoba, however, are just one of several cold-blooded species on Preston's list of undergraduate research subjects. His OSU herpetology resume also includes frogs in Australia and iguanas in the Galapagos.
"OSU really provides undergraduates the opportunity to participate in research from the get-go," Preston notes.
No Snakes in the House
The Canadian snakes curled up in Cordley Hall are close relatives of the garter snakes Dan first discovered as a kid tramping through the fields of western Pennsylvania. His mother's no-snakes-in-the-house rule gave way under the little boy's persistence, and specimens of the harmless serpents were allowed to join the salamanders, frogs, lizards and insects inhabiting his bedroom terrariums. When his parents, an executive recruiter and a social worker, moved the family west, Dan's collection grew as he explored the wooded ravine behind his Portland home.
"I loved mucking around in creeks and ponds with my net and field guide," Preston recalls.
His childhood fascination with reptiles and amphibians was rekindled when he got to college. During a semester at James Cook University in Queensland, Australia, with the OSU Study Abroad program, he volunteered to work with researchers studying a disease called chytridiomycosis in frogs. Scouring the northern Queensland landscape for the creatures that had inspired so many boyhood romps, he determined to become a research biologist specializing in reptiles.
Taking further advantage of OSU's broad undergraduate research options, this one funded by an OSU Undergraduate Research Innovation Scholarship and Creativity grant, he spent his final fall term in the Galapagos Islands studying intertidal ecology involving yet another scaly vertebrate, the marine iguana. This work was done with Luis Vinueza, a Ph.D. student in the lab of marine biologists Bruce Menge and Jane Lubchenco.
But Preston's formal scientific research actually began while he was still in high school. Instead of just hanging around with his homies, Preston spent several summers at the side of microbial ecologist Anna-Louise Reysenbach through Saturday Academy's Apprenticeships in Science and Engineering program. The Portland State University researcher, who studies bacteria in terrestrial hot springs and deep-sea hydrothermal vents, took the high school intern into her lab (where he grew bacteria in high-temperature, low-oxygen conditions) and into the field (where he collected microbes in Yellowstone National Park).
"We had special research permits to hike off the trail," says Preston, for whom "off the trail" holds great appeal. "We were collecting Aquificales, these long, filamentous microbes, stringy bacteria, that clump together and use minerals for energy and that give thermal pools their bright colors."
Preston cultured a bacterium called Hydrogenobacter subterraneus, originally isolated in Japan. "We found the same organism growing in Yellowstone," Preston says. "The isolate from Japan was a heterotroph, meaning it uses organic compounds, such as sugars, as a source of carbon. The strain I isolated from Yellowstone, while genetically identical, was able to grow as an autotroph, meaning it could use carbon dioxide as a carbon source. This was interesting because previously, H. subterraneus was considered one of the only Aquificales to be a strict heterotroph; nearly all other members of the group are autotrophs." The finding became a small part of a larger paper on the phylogeny of the entire group of bacteria studied in the lab under Dr. Reysenbach.
When he got to OSU, Preston continued his studies of microbes in the lab of microbiologist Steve Giovannoni, where he worked with Ph.D. student Olivia Mason, one of Reysenbach's former master's students.
For the snake study, funded in part by a Howard Hughes Medical Institute Fellowship, Preston is comparing the effectiveness of an injectable anesthetic against that of several other drugs used in veterinary medicine. Anesthesia is critical in the Mason lab, where experiments to better understand reproductive biology and physiology depend on surgical procedures. "Dr. Mason and Dr. Mosley are great mentors," Preston says. "They let me follow the questions I find interesting and design my own experiments. And they're available whenever I need input."
Garter snakes aren't the only reptilian species inhabiting OSU's Zoology Department. Mason's studies include tropical snakes, which reside in the hotter of the two environmental chambers. "It's going to feel like south Florida in here," Preston warns as he leads the way into the bright, hot space about the size of a one-car garage. Pointing out several brown tree snakes, Preston explains Professor Mason's search for solutions to the invasive reptiles' voracious appetite for birdlife on Guam. Then he opens the tank of a three-foot-long African ball python, so-called because of its defensive coiling strategy. "Want to touch her?" he asks as the muscular reptile curls around his arm, flicking her tongue rhythmically. Her scales feel buttery soft and closely textured, like the skin of an orange. "This is snake No. 11." Lab animals get numbers, not names, Preston explains.
He may not befriend his research subjects, but their wild cousins have his complete commitment.
"When I went to South America, I saw firsthand the devastations of oil drilling, deforestation and rampant population growth in the Ecuadorian Amazon," Preston says, explaining his plans to pursue a Ph.D. in conservation biology with a focus on tropical reptiles and amphibians. "The threats can seem insurmountable, but we can make a difference. We've got to keep that hope."