Natures wonders: using antifreeze in frozen climates (Introduction)

by David Turell @, Monday, July 09, 2018, 20:58 (437 days ago) @ David Turell

Many animals do this, but this study is in an insect:

https://phys.org/news/2018-07-antifreeze-proteins-ice-cold.html


"How do insects survive harsh northern winters? Unlike mammals, they don't have thick coats of fur to keep warm. But they do have antifreeze. Antifreeze proteins (AFPs) prevent ice from forming and spreading inside their bodies.

"The existence of these AFPs has been known for decades, but the mechanisms governing this unique survival technique have proven difficult to determine.

"AFPs prevent water from freezing by surrounding and quickly binding to small ice crystals, where water has already managed to order itself into an ice lattice. Left unattended, these crystals would otherwise act as seeds and continue to spread their ordering to neighboring water molecules. The prevailing hypothesis for how AFPs stop this mechanism has been the preordering of an ice-like layer of water near the site of the protein that binds to the ice surface.

***

"Focusing on the AFP of the mealworm beetle, Tenebrio molitor(TmAFP), the study aimed to test this hypothesis through theoretical methods at different resolutions of space and time. Molinero specializes in simulating ice at larger scales and applied this expertise to a system with TmAFP in water approaching an ice surface. With this setup, she and her doctoral student Arpa Hudait observed the protein slowly tumbling above the ice surface. They discovered that to latch on to the ice, all TmAFP requires is to be parallel to the surface.

"Importantly, however, this anchoring did not require any prior ordering of the water into an ice-like structure. "The slow movement of the protein to be parallel to the ice surface is followed immediately by a fast reorientation of the nearby water to bind the protein to the ice," Hudait says. In insects like the mealworm beetle, this binding of many AFPs to developing ice crystals prevents further crystallization of ice in their bodies."

Comment: Arctic fish have been shown to have the same mechanism. We do know how this evolved: were the insects i a climate that gradually cooled or did they speciate with this ability in one step?


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