Using wildlife as sentinels for human health

French

Photo: Caren Helbing (middle) with lab members Jessica Round (left) and Emily Koide (right).

When Caren Helbing and her lab discovered that triclosan — an antimicrobial chemical found in such consumer products as toothpaste, deodorant and cutting boards — can disrupt thyroid hormone action in frogs, she knew it was important because the substance is so prevalent in our daily lives. What she didn’t know was that her research would eventually lead to Canada putting the substance on a list of items that must eventually be phased out in this country.

That’s the kind of ground-breaking research Helbing, a professor of Biochemistry and Microbiology, conducts at the University of Victoria. In particular, she studies thyroid hormones, which are essential to human development and are particularly important when a baby is born because they’re crucial for proper development of the neurological system. The hormones remain important throughout a person’s life because thyroid dysfunction can affect metabolism, memory, heart function and even hearing. Given that, scientists must understand how they work and also what hampers their proper functioning.

To do this work, Helbing studies North American bullfrogs, amphibians that are particularly sensitive to thyroid hormones. It’s all with a goal of understanding how the natural environment affects the little critters and extrapolating that understanding to thyroid function in humans.

“Wildlife are sentinels of the environment and tell us whether our ecosystems are healthy or not,” Helbing explains. “Frogs live in the environment and they’re very sensitive to thyroid hormones which they need in order to actually turn into a frog from a tadpole. By studying them, we can learn a lot about how thyroid hormones affect cells and about the potential of pollutants to harm human health.”

That’s where the resources offered by Compute Canada and its regional partner WestGrid are essential. Helbing’s studies require high-powered computing to look at the genome or the blueprint of life. Using computers, she looks at how the genome is read during the process of metamorphosis and how the hormone affects that.

She says it’s often tricky to nail down that it’s thyroid hormone malfunction that’s causing trouble and that’s where tadpole sensitivity comes in. Her lab is learning that many environmental contaminants such as pharmaceuticals and personal care products that are released into the environment are indeed affecting thyroid function in frogs.

“Part of it is identifying when there is a substance or mixture of chemicals, for example in municipal wastewater effluent, that disrupts thyroid hormone action,” she says. “We’re using the frog to detect and learn about all these things. We’re developing tests based on genomics that we can use to identify when there are endocrine disruptors present. We’re particularly interested in how biological molecules are affected by thyroid hormones, so we can identify what’s normal and what’s not.”

Another corollary to her work is that frogs are the most threatened group of vertebrates on the planet. The work she’s doing, using genomics as a base, will help save frogs species around the world.

“The size of the genome makes it a challenge to put the pieces together to get a full picture of what that genetic blueprint looks like,” she says. “But the bullfrog has a lot of similarities in terms of development that makes it comparable to human development. It’s a lot easier to study a tadpole than a human fetus, for example. Yet many of the changes that happen during frog metamorphosis happen in humans around birth. So we can use the frogs’ extreme response to our advantage to study it and identify when perturbations happen.”

It’s the size of the frog’s genome, which has close to six billion base pairs compared to the human genome’s three billion that plays into her need for high-powered computing.

“It’s really tricky to put all of those pieces together in the right order — it’s like doing a puzzle with six billion pieces,” she says.

“Not only is assembling the blueprint very challenging but now what we’re wanting to do — and are doing — is actually looking at what components of the blueprint are being used at any given time,” Helbing said. “We’re looking at millions of molecules that are being selectively used. When thyroid hormone is present, we’re studying the change.”

Helbing says they couldn’t do this work without Compute Canada and WestGrid.

“It’s invaluable and this resource is supporting really critical work that forms the foundation for innovative research and practical applications,” she says.

 

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