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First published online December 3, 2004
Journal of Experimental Biology 207, iii (2004)
Copyright © 2004 The Company of Biologists Limited
doi: 10.1242/jeb.01385
Inside JEB |
BLINDINGLY COLD
yfke{at}biologists.com
|
At subzero temperatures, many animals would discover that their eye lenses go cloudy as they develop cold-induced cataracts. But the giant Antarctic toothfish has no problems seeing, despite living in permanently freezing Antarctic seas. To investigate the incredible cold stability of Antarctic toothfish eye lens proteins, Andor Kiss, Art DeVries and Chi-Hing Cheng at the University of Illinois decided to compare lens crystallin proteins from Antarctic toothfish, warm-water fish and cows (p. 4633). They hoped that studying lenses from three different thermal environments would shed light on the relationship between lens protein cold-stability and body temperature over evolutionary timescales.
The team already knew that eye lenses contain three classes of protein:
, ß and
crystallins. Mammalian
crystallin is a
small heat shock protein with chaperone-like ability, that is, it prevents the
aggregation and precipitation of heat-damaged proteins. Using in
vitro chaperone assays the team found that fish
crystallins
protect same-species
crystallins from heat damage, just like mammalian
crystallins do. But cow
crystallins did not protect toothfish
crystallins from soaring temperatures. The team suggests that
structural changes in the toothfish proteins prevent cow
and toothfish
crystallins from interacting successfully. These structural changes
likely reflect the evolutionary changes that enabled the Antarctic toothfish
eye lens to adapt to extreme cold. So the Antarctic toothfish has its unique
crystallins to thank for perfect vision in its frigid home.
References
Kiss, A. J., Mirarefi, A. Y., Ramakrishnan, S., Zukoski, C. F.,
DeVries, A. L. and Cheng, C.-H. C. (2004). Cold stable eye
lens crystallins of the Antarctic nototheniid toothfish Dissostichus
mawsoni Norman. J. Exp. Biol.
207,4633
-4649.
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