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Applying the Fishes' Antifreeze Solution
| Article
# : |
19577 |
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Section : |
NATURAL SCIENCE
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| Issue
Date : |
11 / 1991 |
3,380 Words |
| Author
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Thomas Caceci
Thomas Caceci is an associate professor of biomedical
sciences
at Virginia Polytechnic Institute and State University in
Blacksburg, Virginia. |
On a cold winter night you're driving home an hour after a snowfall has begun. Turning a corner, your car skids, but you recover control and arrive without further problems. This common scene is one interaction between man and ice. Another is the moment of beauty present on a moonlit winter night with quiet snowfall. And, of course, everyone appreciates an iced drink on a hot summer afternoon. Ice is so much a part of the world that we may have given little thought to the problems it can cause. But at the cellular and physiological level, things are more complex.
Our planet is unique in that water exists on it in three phases: liquid, gas (in atmospheric water vapor), and solid (as ice). Much of the earth's water is "stored" as ice: in glaciers and the perpetual snow cover of mountain peaks, and in the polar ice caps. During evolution, life, which originated in the warm sea, has had to adapt to the physical and physiological problems of ice in living systems, in order to exploit frigid ecological niches. In our modern technological world ice may also cause problems for agricultural and mechanical systems operating in geographical regions where temperatures may drop below the freezing temperature. The strategy that some animals use to prevent ice from forming in their bodies may provide a means to deal with some of the problems ice causes for man.
It has been known for years that many fishes in the polar oceans can survive indefinitely in seawater cooled to below the freezing temperature of fresh water. If a warm-water fish were placed in these conditions, it would soon freeze solid, with all of the water in its body converted into crystalline ice and unavailable as a solvent of metabolic reactions. Expanding as they formed, the ice crystals would physically rupture the delicate membranes that form the limits of the body's cells. How is it that some marine creatures can avoid this kind of fatal internal ice formation? And what implications does it have for man's efforts to deal with ice and its hazards?
The answers lie in the body chemistry of the protected fishes. They produce natural "antifreezes" that are capable of inhibiting the growth of ice crystals at temperatures the animal normally encounters. There are several classes of natural fish antifreezes, all thought to act by the same mechanism. Some of these antifreeze materials are relatively simple proteins and their biochemistry is currently a subject of intense study. By gaining an understanding of the molecular structure and mechanism of operation of antifreeze proteins, researchers hope to produce significant benefits for agriculture and
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