The Martin lab recently explored why Antarctic toothfish don't get cataracts.

As part of an ongoing effort to understand the phenomenon of cold cataract, a phase separation that occurs in mammalian eye lenses below 20 degrees C, the Martin lab recently identified differences in sequence, hydrophobicity, and protein stability that are important for optimizing the low-temperature performance of eye lens crystallins from the Antarctic toothfish, which lives at -2 degrees C and does not get cold cataract.

Researchers in the Martin group are studying eye lens proteins from organisms that live in very cold water in order to understand the phenomenon of cold cataract, in which the crystallin proteins making up the eye lens partition into protein-rich and protein-poor phases. Mammalian eye lenses undergo a phase separation at temperatures below 20 degrees C. Although this transition is reversible, it causes the lenses to become opaque at low temperature.  The Antarctic toothfish swims in the freezing waters of the Southern Ocean where the temperature is about -2 degrees C year round. The structural eye lens proteins of this fish are homologous to the mammalian ones, yet it does not get cold cataract. Amino acid sequence analysis and biophysical characterization of two γS-crystallin proteins from the toothfish suggest that differences in hydrophobicity and arginine-mediated salt bridges are important for optimizing the low-temperature performance of these structural proteins. Furthermore, these proteins have unusual biophysical properties: their resistance to chemical and thermal denaturation is not correlated. The toothfish crystallins therefore present a useful model system for studying protein stability and denaturation.  See paper.