A red-eyed tree frog in Panama. Agalychnis callidryas is one of many species worldwide facing declines.
photo by Douglas Woodhams
Researchers to track declining frog populations
Frogs around the world are in trouble. And as species are lost, so are their biological treasures.
The National Science Foundation has awarded a team of Vanderbilt University Medical Center investigators a four-year grant to study amphibian declines in Central America and California.
“Amphibian skin has long been favored in folklore for its medicinal properties,” said Louise A. Rollins-Smith, Ph.D., associate professor of Microbiology & Immunology and principal investigator of the new grant. “Frogs are a rich source of potentially useful molecules that might work against human pathogens.”
Rollins-Smith collaborated with Derya Unutmaz, M.D., assistant professor of Microbiology & Immunology, and other Vanderbilt scientists to show this month that compounds from frog skin block HIV infection.
Frogs produce and secrete compounds called antimicrobial peptides to fight off bacteria, fungi and viruses that land on their skin, Rollins-Smith explained.
“Frogs have evolved over millennia to combat such pathogens, so we want to learn from the frog as much as we can about these molecules,” she said.
With the new grant, Rollins-Smith and her team will be investigating the antimicrobial defenses of declining frog populations that are facing a particular skin fungus. Postdoctoral fellow Douglas C. Woodhams, Ph.D., will be traveling to sites in Panama and in California to collect samples of the skin peptides from affected frogs.
“Our goal is to study frog populations that are ahead of an epidemic of this fungus, and those that are behind an epidemic to see if the ones that have survived have beneficial protective peptides,” Rollins-Smith said.
The Mass Spectrometry Research Center at Vanderbilt is particularly valuable to the team's studies. Using mass spectrometry, it is possible to characterize the array of peptides in the samples and rapidly focus on and sequence those that might be antimicrobial.
“We hope to figure out which species are most vulnerable to this fungal pathogen so that they can be the focus of greater conservation efforts,” Rollins-Smith said.
The studies may also reveal new antimicrobial peptides which could be useful blockers of human pathogens, she added.