Wednesday, 04 January 2017 14:20

Microbiomes in Far-flung Places: Characterizing the Arctic Inuit Gut Microbiome

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Published in mBiosphere

The hamlet of Resolute Bay is a tiny Arctic village in the Nunavut territory of Canada with a population that hovers at or below 300. Over hundreds of perhaps even thousands of years, the traditional Inuit diet in Resolute Bay and elsewhere has been dictated by the Arctic environment. The diet is typically low on fresh fruits and vegetables. It's also high in sea game, including caribou, muskox, seal, whale, and fish, that may be eaten cooked, raw, fermented or frozen. The only way to get to Resolute Bay is by small plane — or large boat when the sea ice breaks up in the summer months. Fruits, vegetables, and supermaket goods are shipped in, though shipments may be delayed by bad weather. (image: muskox in Resolute Bay. credit: Catherine Girard)

“It’s not entirely cut off from the rest of the world,” says Jesse Shapiro, a computational evolutionary biologist at the University of Montreal, “but it’s pretty close.”

The isolation of Resolute Bay makes it an appealing research site. The last few years have brought a surge of interest in isolated, often far-flung communities by microbiologists who want to know more about the gut microbiome and its relationship to what we eat. Many of the early studies that mapped out the diversity of microbes in human intestines exclusively studied samples from people who ate a Western diet — high in red meat, fats, and carbohydrates, with lesser contributions from whole grains and fresh vegetables. But a person’s diet is tightly connected to their intestinal flora, and people who eat different foods may host different microbial communities.

Recent microbiology studies on hunter-gatherer communities in remote pockets of Burkina Faso, Tanzania, and Venezuela have revealed that people who live in these villages often host a higher diversity of microbes in their gut. The traditional diet for these people typically includes more plant-based foods and more fiber, and high-fiber diets have previously been linked to greater microbial diversity in the gut.

Shapiro, in Montreal, knew about those studies when he and his colleagues at the University of Montreal set out to characterize the gut microbiome of the Inuit in Resolute Bay. They compared samples from 19 Inuit volunteers to those from 26 people in urban Montreal, but the findings didn’t line up with previous work. The Inuit microbiome bore an uncanny resemblance to a Western microbiome, with a lower diversity than the researchers expected. The Inuit in Resolute Bay don’t have a lot of fiber in their diet and are in the process of transitioning to Western diet, says Shapiro, which may help explain why their gut microbiomes are lacking in diversity.

But the new study goes beyond an academic interest in the global microbiome populations. It was borne out of a concern for poison. Catherine Girard is a PhD student at the University of Montreal, and for years she’s been working with ecotoxicologist Marc Amyot to better understand mercury in foods. Mercury is a neurotoxin to humans, and due to forces in the atmosphere and the sea, it gravitates to the Arctic and accumulates in the animals that live there in its toxic, organic form of methylmercury. That means the Inuit diet, which relies on these creatures, could expose the inhabitants of Resolute Bay to dietary mercury.

Click here to read the mSphere report.

“What’s the role of the gut microbiome in protecting populations in the Arctic — or in making them more or less susceptible to the effects of mercury in their diet?” asks Shapiro. The group’s study published this week in mSphere is a first step toward identifying those microbial players, and possibly finding ways to help people whose traditional diet may be mercury-laden.

That’s why, last summer, Girard and others set out to work with the community of Resolute Bay to collect samples and conduct interviews. They boarded plane after plane and made the arduous, expensive trip to the North. Getting there is difficult and relies on planes with pilots who can land by sight — and can read the weather to look for signs of danger.

In a sense, the finding by Shapiro and his group that the Inuit microbiome is similar to that of a Western gut is a negative result — but will still be instrumental in understanding how to move forward with research. He says the new study isn’t completely representative of all the Inuit in the Arctic, but it does represent a first step not only in understanding the microbiome of this far-flung community in transition, but also in finding ways to prevent mercury poisoning. The group is now preparing to look at the metagenome, searching for mercury resistance genes and metabolism genes that might play an important role.

Last modified on Wednesday, 04 January 2017 15:10
Stephen Ornes

Stephen Ornes is an award-winning science and medical writer in Nashville, Tennessee, whose articles have appeared in Scientific American, Discover, The Washington Post, Cancer Today, Science News for Students, and other outlets. His first book was a 2008 young adult biography of mathematician Sophie Germain, and he contributed two chapters to The Science Writers' Handbook. Visit him online at stephenornes.com, or on Twitter @stephenornes.

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