Functional and comparative studies of haemoproteins from polar fishes

• Main Author: Riccio, Alessia
• Format: Doctoral or Postdoctoral Thesis
• Language: Italian; English
• Published: 2011
• Subjects: Arctic; Antarctic; The Antarctic; Greenland; Antarc*; Gadus morhua; Icefish
• Online Access: http://www.fedoa.unina.it/8865/; http://www.fedoa.unina.it/8865/1/Alessia_Riccio_XXIV_ciclo.pdf; https://doi.org/10.6092/UNINA/FEDOA/8865

Proteins, such as the members of the globin superfamily, are sensitive to temperature and their properties are the result of a long process of adaptation to the conditions encountered during the species evolution. The globin superfamily comprises globular proteins that reversibly bind gaseous ligands such as O2, CO and NO to a haem prosthetic group, Fe-protoporphyrin IX. The globins of this family are the components of classical haemoglobin (Hb) and myoglobin (Mb), but also of neuroglobin, cytoglobin (Cygb), globin X, globin Y and eye-globin. In this study, particular attention has been given to biochemical and physico-chemical characterisation of two proteins. On one hand, the O2 transport systems from two Arctic fish species (Lycodes reticulatus and the cod Gadus morhua) have been investigated. On the other, Cygb has been studied from two Antarctic fish species, one belonging to the family Channichthyidae (icefish) lacking Hb and Mb (Chaenocephalus aceratus) and one red-blooded species belonging to the family Nototheniidae (Dissosticus mawsoni). The Arctic and Antarctic regions have the low temperature in common but differ in geographic position and history. The Antarctic is a continent isolated by the Polar Front, a circular oceanic system, and the temperatures are constantly close to -1.87°C. In contrast, the Arctic is essentially an ocean that lies between North America, Greenland, Europe and Asia. There are strong currents with high temperature variations. The Arctic and Antarctic icthyofaunas are very different. In the Antarctic, a single group of teleost fishes is dominant, the suborder Notothenioidei, that includes eight families. The modern family Channichtyidae is particularly interesting because its species have coulorless blood, lacking Hb and in some cases Mb. In contrast, in the Arctic there are six marin groups, nobody being dominant. Given a shorter evolutionary time at polar temperatures, than the Antarctic ichthyofauna, Arctic fish may provide valuable information on the effects of ...