Researchers solve mystery of how marine mammals hold their breath

June 14, 2013

Researchers solve mystery of how marine mammals hold their breath

How long can you hold your breath?

Researchers from the University of Liverpool have solved the mystery of how marine mammals, like the sperm whale, hold their breath for long periods of time when diving underwater.

The researchers found a unique molecular signature of the oxygen-binding protein myoglobin in diving animals, which gave them the opportunity to examine the evolution of the muscle oxygen stores in more than 100 mammalian species.

Top-notch mammalian divers have high concentrations of myoglobin, according to a news release from the University of Liverpool. In fact, the concentration of myoglobin is so high that the muscle is nearly black in color instead of red. Not until this study was conducted, however, did researchers understand how this molecule is modified in super mammalian divers.

At high concentrations, proteins like to stick together, which hinders their capacity to do their job. This fact made it uncertain how myoglobin assisted the body with storing enough oxygen to give mammals the ability to diver underwater for long periods of time without surfacing for air. Champion mammalian divers, for example, are able to hold their breath for more than 60 minutes while they look for food. Land mammals, on the other hand, are only able to hold their breath for a few minutes.

According to Dr. Michael Berenbrink, from the University of Liverpool’s Institute of Integrative Biology, the researchers examined the electrical charge on the surface of myoglobin and discovered that it increased in mammals that were elite mammalian divers. They observed the same molecular signature in whales, seals, beavers and muskrats.

Berenbrink says that researchers were able to reconstruct the muscle oxygen stores in the ancient ancestors of today’s diving mammals by mapping this molecular signature onto the family tree of mammals.

Dr. Scott Mirceta, a PhD student working with Berenbrink on the study, notes that the results support the idea that the increased electrical charge of myoglobin in mammals that have high concentrations of this protein leads to electro-repulsion. Electro-repulsion stops the proteins from sticking together and gives way to much higher concentrations of myoglobin in the muscles of elite mammalian divers.

Mirceta says that researchers can now order the anatomical changes that took place during the land-to-water transitions of mammals with their confirmed physiological diving capacity. This helps researchers determine the prey that were accessible to the ancient ancestors of today’s diving mammals, as well as their significance for ancient aquatic ecosystems.

“Our findings support amphibious ancestries for echidnas, talpid moles, hyraxes, and elephants, thereby not only establishing the earliest land-to-water transition among placental mammals but also providing a new perspective on the evolution of myoglobin, arguably the best-known protein,” write the researchers in the journal Science.

Researchers hope that the study’s findings will better their grasp of several human diseases where protein gathering is an issue, like Alzheimer’s and diabetes. According to Berenbrink, the results show the power of bringing together molecular, physiological and evolutionary approaches¬†to solve complex biological issues.

The study’s findings are described in detail in the journal Science.

How long can you hold your breath? How can researchers use these findings to help scientists identify treatments for diseases like Alzheimer’s and diabetes? Sound off in the comments section.


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