Aim: 

Copper-zinc superoxide dismutase (Cu,Zn SOD) is an ubiquitous cytosolic enzyme, which catalyzes the dismutation of superoxide radicals to hydrogen peroxide and oxygen. This protein is extremely conservative. Also in organisms adapted to extreme environmental conditions such as Antarctica (characterised by increased pO2), this enzyme maintains its typical functional properties. The aim of this study research was to study the molecular evolution of this protein in Antarctic teleosts, with particular reference to icefish.

Methods: 

Specimens of Pagetopsis macropterus, an icefish widely distributed in Antarctic Ocean, were sampled in the Ross Sea (Terra Nova Bay, 74°42'S, 164°7'E) during the XVII Italian Antarctic Expedition. cDNA sequence of Cu,Zn SOD has been obtained from hepatic tissue by a combination of RT-PCR, 3' and 5'RACE techniques. The obtained nucleotide sequence and the deduced amino acid sequence were compared to those of other teleosts.

Results: 

Multiple alignment comparison and phylogenetic analyses reveal that Cu,Zn SOD sequence from P. macropterus is very closely related to the Antarctic Cu,Zn SODs and clearly separated from those of other teleosts.

Conclusion: 

Of remarkable interest is that this amino acid sequence is longer than other Cu,Zn SOD (163 versus 154 aa) as is the case of another icefish, Chionodraco hamatus. (PNRA and MIUR grants)