Locations

Moscow

info@uidaho.edu
Phone: 208-885-6111
Toll-free: 88-88-UIDAHO
Fax: 208-885-9119
Student Union Building
875 Perimeter Drive MS 4264
Moscow, ID 83844-4264

Boise

Phone: 208-334-2999
Fax: 208-364-4035
322 E. Front Street
Boise, ID 83702

boise@uidaho.edu
www.uidaho.edu/boise

Coeur d'Alene

Phone: 208-667-2588
Toll-free: 888-208-2268
Fax: 208-664-1272
1031 N. Academic Way,
Suite 242
Coeur d'Alene, ID 83814

cdactr@uidaho.edu
www.uidaho.edu/cda

Idaho Falls

Phone: 208-282-7900
Fax: 208-282-7929
1776 Science Center Drive, Suite 306
Idaho Falls, ID 83402

ui-if@if.uidaho.edu
www.uidaho.edu/idahofalls

Yellow Frog

Fighting Killer Frog Fungus

Modern Genetics vs. Ancient Frog-Killing Fungus: Round One

Scientists at the University of Idaho currently are involved in a CSI-like investigation of a killer known to have been running rampant for the past decade. But the killer’s name can’t be found on the FBI’s Most Wanted list. Instead, it’s on the minds of ecologists on every continent in the world.

Its name is Batrachochytrium dendrobatidis (Bd). It is a “chytrid” fungus that lives on keratin, a type of protein found in the skin of amphibians, and is particularly deadly for certain species of frogs. A summary of key findings from the 2004 Global Amphibian Assessment states that 43 percent of all frog species are declining in population. Although there are many reasons for frog decline, including climate change and habitat loss, Bd seriously is affecting a growing number of species.

“This fungus is really bizarre,” says Erica Bree Rosenblum, assistant professor of biological sciences at the University of Idaho. “It’s a member of a group of ancient fungi that are at least a half billion years old. But it only recently began killing amphibians and unequivocally is responsible for a lot of the catastrophic frog die-offs during the past decade.”

Previous studies have shown that once Bd is introduced to a habitat, up to 50 percent of amphibian species and 80 percent of individuals may die within one year. The fungus has been studied for the past decade, yet scientists still do not know much about how Bd kills its host.
However, Rosenblum’s research brings scientists one step closer to solving the mystery. The research uses some of the most advanced genetic technology available in an attempt to understand how the fungus works at the most basic level. It identifies several gene families for future study, including one strong candidate that may be a key element in the killing process.

The family of genes in question, known as fungalysin metallopeptidase, has only one or few representative in similar fungi that do not kill frogs. But in this deadly fungus, genes in the family appear 29 times. Additionally, the genes generally are turned on when the fungus is mature and infecting frogs, but turned off young and swimming in water.

Although this gene family is an excellent candidate for the pathogen’s killing ability, it is not certain. Discovering for sure which genes raise or lower the fungi’s killing ability is a long process, partly because the fungus is so far removed from other organisms in the evolutionary tree.

“This fungus is strange and different, partly because it is so ancient,” says Rosenblum.

Rosenblum is currently comparing active genes in Bd grown on frog skin to Bd grown in a test tube without exposure to keratin. Also, she plans to sequence genomes from different strains of Bd that kill less efficiently, or other, similar fungi that don’t kill amphibians at all.

“One of the really amazing and wonderful things about this genetic technology is that we can take something we don’t know anything about, sequence its whole genome, look at what each gene is doing in different life stages, and learn a tremendous amount about the organism.”

Learn more about Erica Rosenblum's laboratory.