Lipid transport, lipid metabolism and cold adaptation in Antarctic notothenioid fish

Fish species of the suborder Notothenioidei are morphologically distinct in that they lack a swim bladder. To compensate, high levels of tissue lipids aid in maintaining buoyancy. The lipids also increase the diffusing capacity of oxygen and provide an energy store to support aerobic metabolism. The oxidation of fatty acids - derived from lipid stores - is the preferred metabolic fuel in this group of fish. Previously it was found that in the Antarctic toothfish, fatty acid transport is carried out using high density lipoprotein in blood, as opposed to a long chain fatty acid transporter, albumin. Research was conducted over three seasons with the aim to increase biochemical and genetic knowledge of Antarctic notothenioid fish, to determine whether the loss of albumin expression and the utilisation of alternative proteins, such as high density lipoprotein, for lipid transport is an adaptation of Antarctic fish to their extreme environment and therefore common across the Antarctic notothenioid fish. All investigations hoped to contribute to the question "What are the main factors that have driven the evolution of individual species in the Southern Ocean?" A number of individuals from 9 notothenioid and 1 non-notothenioid species were captured in the McMurdo Sound and Terra Nova Bay area including Pagothenia borchgrevinki, Trematomus pennellii, T. bernacchii, T. nicolai, T. hansoni, T.newnesi, T. eulepidotus, Gymnodraco acuticeps, Chionodraco hamatus and Lyodichthys dearborni. Blood and tissue (heart, liver, spleen, red muscle, white muscle, kidney, intestine, brain, eye, gill and adipose) samples were harvested and frozen for analysis. Not all tissue types were taken from all fish species. Blood protein analyses were performed using electrophoresis and [14C] palmitic acid binding. In addition, fish length, weights, gonadosomatic indices and parasite load were measured and sex was recorded and in some cases gonads were taken for histological analysis.