“Grade-five curiosity and frogs definitely go together!” laughs Dr. Natacha Hogan, associate professor of Biology and associate fellow of the Canadian Rivers Institute. “My research student, Ashleigh, understands the importance of the work, but she still sends me gleeful e-mails letting me know when our tadpoles have sprouted legs.”
Hogan’s lab began this summer building a colony of frogs called Xenopus tropicalis. What started as a gift of six adult frogs from her former lab in Ottawa quickly grew into several tanks filled with wriggling tadpoles at various stages of development.
“These particular frogs are native to Nigeria,” says Hogan, using a small net to fish a tadpole from a bubbling aquarium. “They’re handy for lab work for many reasons. They’re completely aquatic, and never require habitat other than a tank of water. And, they mature to adulthood in six months. If we were to study a native species, such as the northern leopard frog, we’d need complex habitats so they can spend time out of water, and they wouldn’t mature for at least two years.”
Xenopus tropicalis also go through metamorphosis, or change from a tadpole into a frog, in the same way that our native species do. That’s why she can use them to help understand how frogs on Prince Edward Island respond to stresses in their environment.
“I can create environmental stress simply by removing some of the water from a tadpole tank,” explains Hogan. “The hormone pathway that controls metamorphosis says, ‘Uh oh, the water is getting low. It must be late in the season. I’d better hurry up and turn into a frog.’ The result is tiny frogs.”
Hogan says the various hormone pathways that make up the endocrine system are often studied independently of each other, but they don’t work in isolation. She’s studying the points at which the paths intersect.
“So if one system is interrupted, what happens to the other systems? If metamorphosis is compromised, what happens to reproduction? That’s what we’re examining.”
Hogan says frogs in the wild can be exposed to contaminants such as pesticides that block hormone pathways. “Take thyroid hormones, for example. Thyroid hormones control metamorphosis. Block that process, and it won’t take very long before you have a serious problem with the health and survival of the Island’s frog population.”
Hogan’s project is funded by an NSERC Discovery Grant and is called Impact of Thyroid Hormone on Reproduction in Amphibians.
She also works with Dr. Michael van den Heuvel, Canada Research Chair in Watershed Ecological Integrity, on a project assessing fish health in man-made oil-sands affected lakes in northern Alberta. Read the ORD Blog’s profile of that project here.
Photo credit: Ashleigh Allen