Marine mammals dive for long periods - here's how they do it

Marine mammals hold their breath for long periods of time as they dive under water, and now we know how they do it.

Researchers from the University of Liverpool found that a protein called myoglobin present in the bodies of sperm whales and other marine animals could hold onto enough oxygen to provide these animals the ability to make marathon dives under water lasting an hour or more. Myoglobin is the same protein that provides beef its red color.

The concentration of myoglobin in bodies of the longest-duration divers is so high that their muscles are almost black. When proteins are present in large concentrations, they often clump together in a process called protein aggregation, hindering their ability to perform their functions. Because of this behavior, it was previously believed that myoglobin could not function as an effective storehouse for oxygen in the levels present in marine mammals.

But what the international team of researchers found was that there is an increased surface charge present on the myoglobin of the best marine divers. This extra charge creates electro-repulsion due to the similar charges between the molecules, keeping the crowded protein molecules from clumping together.

"We studied the electrical charge on the surface of myoglobin and found that it increased in mammals that can dive underwater for long periods of time. We were surprised when we saw the same molecular signature in whales and seals, but also in semi-aquatic beavers, muskrats and even water shrews," Michael Berenbrink, from Liverpool University's Institute of Integrative Biology, who led the team, said.

The University of Liverpool researchers who made the discovery were able to find evidence the chemical is also present in around 100 species of marine animal as well.

"By mapping this molecular signature onto the family tree of mammals, we were able to reconstruct the muscle oxygen stores in extinct ancestors of today's diving mammals. We were even able to report the first evidence of a common amphibious ancestor of modern sea cows, hyraxes and elephants that lived in shallow African waters some 65 million years ago." Berenbrink said.

This research may benefit research into diabetes and Alzheimer's, where protein aggregation is involved.

The new findings surrounding the role of myoglobin in marine mammals were published in the journal Science.

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