June 2, 2010
The Weddell seal is one of the deepest diving seals on earth and can hold its breath underwater for up to 90 minutes in their native habitat of Antarctica. Scientists have just begun to unravel what physiological characteristics in the seals' swimming muscles allow them to dive so deep and for so long. But now, new research from Baylor University biologists has found that there is a switching of fuel usage as this animal goes from a non-diving pup to a juvenile diver.
The study is the first to show that an animal has the ability to switch what type of fuels they burn in their muscles.
The study appeared in the Journal of Experimental Biology.
"This is truly a remarkable finding," said Dr. Stephen Trumble, assistant professor of biology at Baylor in the College of Arts and Sciences, who has extensively studied seals. "From some of our previous work, we found that certain physiological characteristics in the swimming muscles of these animals change with age like myoglobin, fiber type and some aerobic and anaerobic enzymes. Now, it certainly seems the cellular function also is changing such that the seals oxidize fuels slower and more efficiently. This is key because it allows them to forge longer and survive in one of the harshest environments on the planet."
The Baylor study looked at 50 Weddell seals as they aged from pups to mature adults. The researchers took muscles biopsies and analyzed how the muscles burn fuel.
The study found as the seals mature from a non-diving pup to a mature adult, they gradually switch from using saturated fatty acids in their skeletal muscle for fuel to polyunsaturated fatty acids like omega-3s.Trumble said researchers noticed a switch beginning when the seal is approximately one-year old. The researchers believe that this switch may be a cellular trigger to initiate diving because there is a strong link between skeletal muscle lipid composition and lipids in the membrane of the muscle and cellular metabolism.
The long-range implications of the Baylor study could help researchers unlock mysteries related to human conditions as well, Trumble said.
"Another part of this is we know that membrane physiology and its composition are essential for the normal development of the brain, and numerous studies have shown that there is a link between insulin resistance, lipid composition of the skeletal membrane and many diseases involving obesity, hypertension and cardiovascular issues," he said. "So, if we can discover how these seals switch from utilizing one fuel over another in the muscle then we may provide some insight on why we suffer from specific health related problems."
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