Dr. “Skip” Lazauski

Now that the weather has started to get cold it’s time to check the antifreeze in your car.

We put antifreeze into our vehicle to keep the engine block from cracking.

This can happen to the cells in a living organism when it gets too cold.

The water in the cells freezes and expands, rupturing the membrane that encloses the cell. If you don’t think this really happens put a tomato in your freezer overnight and take it out the next morning. Make sure you put it in a bowl or you’ll have a mess to clean up.

If this happens to plants, how do fish survive in temperatures cold enough to freeze saltwater?

Some species of fish have their own “antifreeze molecules” in their blood that allows them to live in subfreezing water. These molecules plug gaps that exist in small ice crystals that start to form in the blood and prevent further growth of the crystals.

These antifreeze molecules are a group of unique proteins that help some coldwater fish to avoid freezing in the icy waters.

Dr. Art DeVries discovered these proteins from fish that he collected at McMurdo Station in the Antarctic while he was a graduate student at Stanford University in the early 1960s.

Waters of the southern oceans are so cold that temperate and tropical fish would freeze if they were placed in these waters. The presence of salt in seawater allows it to remain a liquid until about –28.6F, almost 3.5F degrees below the freezing temperature of freshwater. The antifreeze proteins, along with normal body salts, depress the freezing point of blood and body fluids to 27.5F, which is slightly below the freezing point of seawater.

These proteins bind to and inhibit growth of ice crystals within body fluids through an absorption-inhibition process. The proteins attach to small ice crystals, stemming their growth.

This mechanism that inhibits further growth of the ice crystal remains under study. Apparently, Antarctic fish are able to survive with very small ice crystals present in their body fluids.

There are several companies working on commercial applications of these antifreeze proteins. These antifreeze proteins are about 300 times more effective in preventing freezing than conventional chemical antifreezes at the same concentration.

The effectiveness of these antifreeze proteins in inhibiting ice growth suggests that they might be useful in preventing food from freezing.

For example, they could be used in the cryo-preservation of foods that normally are rendered inedible due to ice crystal damage or to engineer cold resistance in living plants, as well as for the cryo-preservation of tissues and organs. Other areas of study include prevention of kidney stones, gout and gall stones.

Some companies in the frozen dessert industry are studying how antifreeze proteins modify the way that frozen foods recrystallize.

Normally, when a product like ice cream melts and is frozen again it loses its smooth texture as ice crystals begin recrystallizing into larger crystals.

The antifreeze proteins can modify this process and prevent the crystals from growing. Large quantities of the fish antifreeze protein can now be produced through use of DNA recombinant technology in yeast and bacteria.

Think Global – Act Local!

Dr. “Skip” Lazauski can be seen on the television show “Eco-Bites”, which airs on Mediacom’s channel 14 and Smartel’s channel 4. To reach Dr. Lazauski for questions and comments, send e-mail to IchiOrca@yahoo.com. For more information, see his Web site, www.drskiponline.com.