Scientists at the University of Liverpool have uncovered the mystery of how diving marine mammals are able to store enough oxygen to hold their breath for up to an hour.
Myoglobin, an oxygen-storing protein in mammals that gives meat its red color, is present in such high concentrations in diving mammals that their muscle is almost black in color.
But in such high concentrations, proteins usually stick together, impairing their function. Until now, it was unclear how myoglobin was able to help mammals including whales and seals store so much oxygen.
Researchers, led by Dr. Michael Berenbrink of the Institute of Integrative Biology, studied the electrical charge on the surface of myoglobin and found that it increased in diving marine mammals.
"Our study suggests that the increased electrical charge of myoglobin in mammals that have high concentrations of this protein causes electro-repulsion, like similar poles of two magnets," said Scott Mirceta, PhD student on the project. "This should prevent the proteins from sticking together and allow much higher concentrations of the oxygen-storing myoglobin."
"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," Berenbrink said.
"By mapping this molecular signature onto the family tree of mammals," Berenbrink said, "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."
The research could also improve understanding of human diseases where protein aggregation is a problem, including Alzheimer's and diabetes, and could lead to development of artificial blood substitutes.
The research, in collaboration with the University of Manitoba, Canada, and the University of Alaska is published in the journal Science.