Kim, B. et al. Nat. Ecol. Evol. 3, 469–478 (2019)

Antarctic icefishes have evolved some unique adaptations to their extreme polar environments. Notably, the different species of notothenioid fishes are ‘white-blooded’—in order to survive temperatures as low as -1.9 °C, they express antifreeze glycoproteins and lack red blood cells. They could thus be useful models to understand pathological conditions in humans, such as anemia.

To understand the animals and their adaptations better, a team of researchers recently completed a high-quality genome assembly and linkage map for the Antarctic blackfin icefish, Chaenocephalus aceratus. Though in many places the genome of the icefish was highly conserved with red-blooded relatives, the results reveal expansions in genes for antifreeze proteins and those that maintain cellular redox states in the fish. The icefish also lack several genes that regulate circadian rhythms.