While the strongest human swimmers on Earth cannot hold their breath underwater for more than a few minutes, marine mammals such as dolphins and whales can somehow stay comfortably submerged for up to an hour. Marine biologists have long been stumped over how these mammals do it. But a new study may have found the answer: It’s in their blood.
According to the study, which was published in Science and involved six researchers from the universities of Liverpool, Winnipeg, and Alaska, marine mammal species’ blood has a protein called hemoglobin that is a highly effective at storing oxygen.
Human blood has myoglobin, too, but only in trace amounts most of the time. Levels of it spike when an injury, seizure, or heart attack occurs. All mammals have it, in fact. It’s what gives meat its red hue. The marine mammals not only have more of it—so much so that their muscle tissue appears almost black—but theirs has special “non-stick” properties that enable it to convey massive amounts of oxygen into their blood without clogging any blood vessels. The researchers found this distinctively non-stick myoglobin in the blood of whales, seals, dolphins, and some semi-aquatic mammals, too, such as beavers, muskrats, and water shrews.
Proteins in any mammal’s blood stream tend to start clumping together when there are enough of them running through the same network of blood vessels. The unique non-stickiness of the marine mammals’ hemoglobin comes from a positive charge that runs throughout its molecules, according to the study.
One of the researchers, University of Liverpool biologist Michael Berenbrink, likens it to positively charged magnets—their identical forces repel each other. This is a critically important adaptation, because it makes it possible for the marine mammals’ hemoglobin needed to work at high enough concentrations to keep them oxygenated underwater for long periods, and to do so without causing deadly blockages in their blood flow.
The Evolution Story
These new findings on hemoglobin help researchers make much more sense of the path of evolution that land-based mammals had to have begun to undertake many millions of years ago to transition back into the water, according to Berenbrink. He and his colleagues have retraced the physiological developments as they appear in the fossils of whales’ earliest prehistoric ancestors through to the present.
In series of tests led by researcher Scott Mirceta, also of the University of Liverpool, the team scanned fossils covering a full 200 million years of evolutionary history. They topped off their evolutionary assessment with extractions of myoglobin from present-day living mammals, including not only seafaring mammals like the sperm whale, but also the semi-aquatic otter and the purely land-faring cow.
According to Berenbrink, the researchers now have enough data to estimate the diving times of the earliest fossilized proto-whale species. They have also compiled the first evidence of a common ancestor of modern-day sea cows, hyraxes, and elephants. This hypothetical creature would have lived in the waters off the coast of present-day Africa about 65 million years ago. No definitive fossil has been found for this hypothetical ancestor, though, so the researchers will have some more digging to do. But they credit the placing of myglobin development on the evolutionary map as being a critical step, to this and maybe more discoveries about sea mammals evolutionary past.
Marine mammals underwent other key adaptations besides the changes in their myoglobin. Michael Fedak, a sea-mammal researcher at the University of St. Andrews—and who was not involved in the study—told BBC that myglobin was just a piece of the story, but it is “an important” one all the same.
Human Uses
The researchers foresee some potential innovations in human medicine arising from these hemoglobin findings, too. Human clinicians who learn to replicate some of the chemistry could develop oxygen-carrying fluids that they could inject into critically injured patients and keep their tissues alive when blood transfusions are not possible.
Although ER patients often need blood transfusions, many doctors would be glad to have alternatives. Not only is the donor blood potentially costly and sometimes in short supply, but it also carries potential risks of adverse reactions, in the form of fevers or unpleasant allergic symptoms resulting from the patient’s body attacking the transfused blood. Sometimes the adverse reactions are deadly: Studies suggest that as many as 25% of transfusion patients suffer heart attacks within a month of their transfusions.
Many hospitals have been encouraging their physicians in recent years to limit blood transfusions only to cases in which they are absolutely necessary and to substitute lower-impact measures whenever possible.
Could whale blood proteins contribute to one new lower-impact solution? This is an areas for researchers to explore in years to come.
NEWS SOURCE:http://www.sciencerecorder.com
According to the study, which was published in Science and involved six researchers from the universities of Liverpool, Winnipeg, and Alaska, marine mammal species’ blood has a protein called hemoglobin that is a highly effective at storing oxygen.
Human blood has myoglobin, too, but only in trace amounts most of the time. Levels of it spike when an injury, seizure, or heart attack occurs. All mammals have it, in fact. It’s what gives meat its red hue. The marine mammals not only have more of it—so much so that their muscle tissue appears almost black—but theirs has special “non-stick” properties that enable it to convey massive amounts of oxygen into their blood without clogging any blood vessels. The researchers found this distinctively non-stick myoglobin in the blood of whales, seals, dolphins, and some semi-aquatic mammals, too, such as beavers, muskrats, and water shrews.
Proteins in any mammal’s blood stream tend to start clumping together when there are enough of them running through the same network of blood vessels. The unique non-stickiness of the marine mammals’ hemoglobin comes from a positive charge that runs throughout its molecules, according to the study.
One of the researchers, University of Liverpool biologist Michael Berenbrink, likens it to positively charged magnets—their identical forces repel each other. This is a critically important adaptation, because it makes it possible for the marine mammals’ hemoglobin needed to work at high enough concentrations to keep them oxygenated underwater for long periods, and to do so without causing deadly blockages in their blood flow.
The Evolution Story
These new findings on hemoglobin help researchers make much more sense of the path of evolution that land-based mammals had to have begun to undertake many millions of years ago to transition back into the water, according to Berenbrink. He and his colleagues have retraced the physiological developments as they appear in the fossils of whales’ earliest prehistoric ancestors through to the present.
In series of tests led by researcher Scott Mirceta, also of the University of Liverpool, the team scanned fossils covering a full 200 million years of evolutionary history. They topped off their evolutionary assessment with extractions of myoglobin from present-day living mammals, including not only seafaring mammals like the sperm whale, but also the semi-aquatic otter and the purely land-faring cow.
According to Berenbrink, the researchers now have enough data to estimate the diving times of the earliest fossilized proto-whale species. They have also compiled the first evidence of a common ancestor of modern-day sea cows, hyraxes, and elephants. This hypothetical creature would have lived in the waters off the coast of present-day Africa about 65 million years ago. No definitive fossil has been found for this hypothetical ancestor, though, so the researchers will have some more digging to do. But they credit the placing of myglobin development on the evolutionary map as being a critical step, to this and maybe more discoveries about sea mammals evolutionary past.
Marine mammals underwent other key adaptations besides the changes in their myoglobin. Michael Fedak, a sea-mammal researcher at the University of St. Andrews—and who was not involved in the study—told BBC that myglobin was just a piece of the story, but it is “an important” one all the same.
Human Uses
The researchers foresee some potential innovations in human medicine arising from these hemoglobin findings, too. Human clinicians who learn to replicate some of the chemistry could develop oxygen-carrying fluids that they could inject into critically injured patients and keep their tissues alive when blood transfusions are not possible.
Although ER patients often need blood transfusions, many doctors would be glad to have alternatives. Not only is the donor blood potentially costly and sometimes in short supply, but it also carries potential risks of adverse reactions, in the form of fevers or unpleasant allergic symptoms resulting from the patient’s body attacking the transfused blood. Sometimes the adverse reactions are deadly: Studies suggest that as many as 25% of transfusion patients suffer heart attacks within a month of their transfusions.
Many hospitals have been encouraging their physicians in recent years to limit blood transfusions only to cases in which they are absolutely necessary and to substitute lower-impact measures whenever possible.
Could whale blood proteins contribute to one new lower-impact solution? This is an areas for researchers to explore in years to come.
NEWS SOURCE:http://www.sciencerecorder.com
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