KISS, A.J.*; CHENG, C.-H.C: Gamma Crystallins of Antarctic Notothenioid Fishes.

The Notothenioidei suborder of teleost fishes of the Southern Ocean possess antifreeze glycoproteins (AFGPs) that allow them to thrive in the habitually ice-laden Antarctic water. While the AFGPs are the most prominent adaptation of these fishes, other proteins have provided valuable insight into cold adaptation – lactate dehydrogenase, tubulin, and acetylcholinesterase. Gamma crystallins are the major lens crystallin in fish, therefore we have begun to characterise the Antarctic notothenioid GAMMA crystallins, to eventually determine whether there are adaptive changes regarding stability and polymerisation as a consequence of freezing temperatures. Gamma crystallins from the giant Antarctic toothfish, Dissostichus mawsoni, were isolated by size exclusion and ion exchange column chromatography. SDS-polyacrylamide gel electrophoresis shows five isoforms ranging in size between 19 kD to 23 kD. A partial cDNA from the toothfish has been obtained by RT-PCR using primers designed from conserved regions of GAMMA crystallin sequences of carp. With specific primers based on the toothfish partial GAMMA crystallin cDNA we have used RACE to obtain the full length cDNA from cold-water notothenioid species Gymnodraco acuticeps, Pagothenia borchgrevinki, and Trematomus hansoni, and the temperate-water species, Notothenia angustata (from New Zealand). Comparative protein sequence and structural analyses of the lens proteins from these notothenioids may be informative on whether any evolutionary adaptations have resulted from environmental influence.