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Research Communications

Cold Case 

Ido Braslavsky explores how anti-freeze proteins protect critters from the cold

May 21, 2009

Ido Braslavsky

Scientists have long observed that some  insects, fish, bacteria, fungi and other organisms can survive extremely frigid temperatures. Forty years ago, researchers discovered that these critters have anti-freeze proteins in their bodies that protect them from the cold.

But how exactly do these proteins work? That’s a question that Ohio University scientist Ido Braslavsky is trying to answer.

Braslavsky, an associate professor of physics and astronomy, recently received a three-year, $315,000 grant from the National Science Foundation to investigate the mechanisms of anti-freeze proteins. The potential for future applications is promising, he said, because the proteins could guard against freezer burn in foods or could ward off frost on crops. But scientists first need to better understand how and why the proteins prohibit ice growth.

Researchers know that the proteins attach to particular surfaces on an ice crystal, inhibiting growth of the crystal in those spots until the temperature reaches a certain point, he said.

“There are a set of proteins in insects which are hyperactive proteins. In much smaller concentrations, they can do a much better job at stopping ice,” Braslavsky said. “Why are certain proteins more effective?”

His research team—which includes graduate students Yeliz Celik, Yangzhong Qin and Di Xu and visiting researcher Liu Junjie—uses two techniques, fluorescence microscopy and microfluidic devices, to investigate the issue.

With fluorescence microscopy, the researchers use an anti-freeze protein that’s attached to a second protein—the Green Flourescent Protein, commonly found inside jellyfish—that has fluorescent capabilities.  A fluorescent molecule has an electronic structure that facilitates the absorption and emission of light at a different wavelength, enabling the observation of its glow under certain conditions. Once the anti-freeze protein is attached to this fluorescent protein, the team is able to track its position on an ice crystal.

The researchers also use a microfluidic cell during the experiments. The cell has a channel through which the team can flow a temperature-controlled solution around an ice crystal. This method allows the team to observe if and how quickly the ice forms when anti-freeze proteins are not present in a solution. This, in turn, creates a better understanding of how these anti-freeze proteins function, Braslavsky said.

In addition to the Ohio University team, Braslavsky collaborates with experts from around the world. They include Peter Davies, from Queens University in Canada, who creates most of the anti-freeze proteins used in the experiments; John Wetlauffer, an ice expert at Yale University; Alex Groisman, who specializes in microfluidics at the University of California, San Diego; Debbie Fass, an expert in the expression of hard-to-fold proteins at the Weizmann Institute of Science, Israel; and Joel Stavans, an expert in pattern formation at the Weizmann Institute.

Why are so many researchers interested in anti-freeze proteins? Braslavsky points to their potential agricultural and medical applications. An ice storm can wipe out an entire harvest of fruits and vegetables. The growth of ice crystals also can damage organs preserved for medical transplants.

“Anti-freeze proteins can potentially be helpful in protecting tissues from the freezing and thawing process. But so far, it’s not proven effective. We suggest that better understanding of the protein function will prove helpful in their future usage in such applications,” said Braslavsky, who has made several outreach presentations about his research to community audiences at the Athens County Public Library and at East Elementary School.

But the proteins also have potential for use in consumer products. In fact, they already can be found in everyday items. Unilever—the manufacturer of brands such as Lipton, Slim Fast and Dove—produces an ice cream with the proteins to guard against freezer burn. Some cosmetic companies also incorporate the proteins into their makeup, claiming the proteins protect skin membranes from the cold.

By Emily Hubbell

For more information about this research, contact Ido Braslavsky at braslavs@ohio.edu.