How do polar bears stay warm? Research finds an answer in their genes

Feb 10, 2014 by Charlotte Hsu
How do polar bears stay warm? Research finds an answer in their genes
This image shows a male polar bear. Credit: Credit: U.S. Geological Survey, Steven C. Amstrup

(Phys.org) —In the winter, brown and black bears go into hibernation to conserve energy and keep warm.

But things are different for their Arctic relative, the polar bear. Within this high-latitude species, only pregnant females den up for the colder months.

So how do the rest survive the extreme Arctic winters?

New research points to one potential answer: genetic adaptations related to the production of nitric oxide, a compound that cells use to help convert nutrients from food into energy or heat.

In a new study, a team led by the University at Buffalo reports that genes controlling nitric oxide production in the polar bear genome contain genetic differences from comparable genes in brown and black .

"With all the changes in the global climate, it becomes more relevant to look into what sorts of adaptations exist in organisms that live in these high-latitude environments," said lead researcher Charlotte Lindqvist, PhD, UB assistant professor of biological sciences.

"This study provides one little window into some of these adaptations," she said. "Gene functions that had to do with nitric oxide production seemed to be more enriched in the polar bear than in the brown bears and black bears. There were more unique variants in polar bear genes than in those of the other species."

The paper, titled "Polar Bears Exhibit Genome-Wide Signatures of Bioenergetic Adaptation to Life in the Arctic Environment," appeared Feb. 6 in the journal Genome Biology and Evolution. Co-authors include scientists from UB, Penn State University, the U.S.G.S. Alaska Science Center, Durham University and the University of California, Santa Cruz.

The genetic adaptations the research team saw are important because of the crucial role that nitric oxide plays in energy metabolism.

Typically, cells transform nutrients into energy. However, there is a phenomenon called adaptive or non-shivering thermogenesis, where the cells will produce heat instead of energy in response to a particular diet or environmental conditions.

Levels of nitric oxide production may be a key switch triggering how much heat or energy is produced as cells metabolize nutrients, or how much of the nutrients is stored as fat, Lindqvist said.

"At high levels, nitric oxide may inhibit energy production," said Durham University's Andreanna Welch, PhD, first author and a former postdoctoral researcher at UB with Lindqvist. "At more moderate levels, however, it may be more of a tinkering, where is involved in determining whether—and when—energy or heat is produced."

The research is part of a larger research program devoted to understanding how the polar bear has adapted to the harsh Arctic environment, Lindqvist said.

In 2012, she and colleagues reported sequencing the genomes of multiple brown bears, and polar bears.

In a paper in the Proceedings of the National Academy of Sciences, the team said comparative studies between the DNA of the three species uncovered some distinctive polar bear traits, such as genetic differences that may affect the function of proteins involved in the metabolism of fat—a process that's very important for insulation.

In the new study, the scientists looked at the mitochondrial and nuclear genomes of 23 , three and a black bear.

Explore further: Polar bear diet changes as sea ice melts

More information: gbe.oxfordjournals.org/content… /gbe.evu025.abstract

Related Stories

Polar bear diet changes as sea ice melts

Jan 22, 2014

A series of papers recently published by scientists at the American Museum of Natural History suggests that polar bears in the warming Arctic are turning to alternate food sources. As Arctic sea ice melts ...

Recommended for you

Rare new species of plant: Stachys caroliniana

Nov 21, 2014

The exclusive club of explorers who have discovered a rare new species of life isn't restricted to globetrotters traveling to remote locations like the Amazon rainforests, Madagascar or the woodlands of the ...

Mysterious glowworm found in Peruvian rainforest

Nov 21, 2014

(Phys.org) —Wildlife photographer Jeff Cremer has discovered what appears to be a new type of bioluminescent larvae. He told members of the press recently that he was walking near a camp in the Peruvian ...

The unknown crocodiles

Nov 21, 2014

Just a few years ago, crocodilians – crocodiles, alligators and their less-known relatives – were mostly thought of as slow, lazy, and outright stupid animals. You may have thought something like that ...

User comments : 0

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.