Glycoprotein Prevents Ice Crystals

Biological Strategy

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Protect From Ice

Freezing temperatures can be difficult for living systems to manage. They can cause ice crystals to form in blood and tissues, which causes damage to cells and ultimately, death. Living systems can’t afford the energy required to melt ice crystals, so instead, many have strategies to prevent crystals from forming in the first place. Many amphibians, plants, and insects have chemicals that act as antifreeze to prevent icy crystal formation. Another challenge ice presents is that it creates a slick surface, requiring friction to traverse. This is why polar bears’ paws have a rough surface that grips ice.

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Protect From Temperature

Many living systems function best within specific temperature ranges. Temperatures higher or lower than that range can negatively impact a living system’s physiological or chemical processes, and damage its exterior or interior. Living systems must manage high or low temperatures using minimal energy, which often requires controlling responses along incremental temperature changes. To do so, living systems use a variety of strategies, such as avoiding high or low temperatures, removing excess heat, and holding heat in. Insulation is a well-known example of managing low temperatures by retaining heat using thick layers of hair, fur, or feathers to hold warm air next to the skin.

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Fish

Class Agnatha (“without jaws”), Class Chondrichthyes (“cartilage fish”), Superclass Osteichthyes (“bone fish”): Sharks, eels, snapper, hagfish

The fish are a diverse group, comprising multiple classes within Phylum Animalia. The most well-known classes are Chondrichthyes, which has sharks and rays, and superclass Osteichthyes, which has all bony fish like cod and tuna. Unlike other vertebrates, fish only live in water. They use special adaptations like fins, gills, and swim bladders to survive. Most are ectothermic, meaning their body temperature depends on the water temperature around them. Over half of all vertebrates are fish. They’re found from the bottom of the sea to high mountain lakes.

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The blood of some Antarctic ice fishes resists freezing via a glycoprotein that lowers the temperature at which ice crystals enlarge.

“An internal antifreeze stops some animals from freezing in sub-zero temperatures. Some Antarctic fishes and certain species inhabiting Scandinavian fjords, as well as the Alaskan blackfish (Dallia pectoralis), are said to be freezing-susceptible because their bodies do not form ice crystals even in sub-zero temperatures. The blood of Antarctic ice fishes of the genus Trematomus has a that functions very efficiently in preventing the formation of ice crystals; indeed, it is 200-500 times more effective than salt. The glycoprotein lowers the temperature at which ice crystals enlarge, while having no effect upon the temperature at which they melt.” (Shuker 2001:110)

“Antifreeze s (AFPs) and antifreeze glycoproteins (AFGPs) enable
the survival of organisms living in subfreezing habitats and serve as
preservatives. Although their function is known, the underlying
molecular mechanism was not understood. Mutagenesis experiments
questioned the previous assumption of hydrogen bonding as the dominant
mechanism. We use terahertz spectroscopy to show that antifreeze
activity is directly correlated with long-range collective hydration
dynamics. Our results provide evidence for a new model of how AFGPs
prevent water from freezing. We suggest that antifreeze activity may be
induced because the AFGP perturbs the aqueous solvent over long
distances. Retarded water dynamics in the large hydration shell does not
favor freezing. The complexation of the carbohydrate cis-hydroxyl
groups by borate suppresses the long-range hydration shell detected by
terahertz absorption. The hydration dynamics shift toward bulk water
behavior strongly reduces the AFGP antifreeze activity, further
supporting our model.” (Ebbinghaus et al. 2010:12210)

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Last Updated August 18, 2016

References

Book

The Hidden Powers of Animals: Uncovering the Secrets of Nature

26/02/2021 | Dr. Karl P. N. Shuker

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Reference

Journal article

Antifreeze activity of Antarctic fish glycoprotein and a synthetic polymer

Nature | 12/06/2003 | F. Franks, J. Darlington, T. Schenz, S. F. Mathias, L. Slade, H. Levine

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Reference

Why fish don't freeze in the Arctic Ocean

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Reference

Journal article

Antifreeze Glycoprotein Activity Correlates with Long-Range Protein−Water Dynamics

J. Am. Chem. Soc. | 16/08/2010 | Simon Ebbinghaus, Konrad Meister, Benjamin Born, Arthur L. DeVries, Martin Gruebele, Martina Havenith

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