O'Brien Kristin M
University of Alaska Fairbanks, Institute of Arctic Biology, Department of Biology and Wildlife, Fairbanks, AK 99775, USA
Integr Comp Biol. 2016 Oct;56(4):531-41. doi: 10.1093/icb/icw062. Epub 2016 Jun 1.
The loss of expression of the oxygen-binding protein hemoglobin (Hb) in the family Channichthyidae (suborder Notothenioidei) of Antarctic fishes is considered a disaptation that has persisted because of the unusual conditions prevailing in the Southern Ocean during the evolution of the family. The loss of expression of the intracellular oxygen-binding protein myoglobin (Mb) in heart ventricles is more of a conundrum because it occurred at four points during the radiation of the family, suggesting weakened selective pressure maintaining expression of the protein. Yet, studies have shown that when present, Mb enhances function. Here, I discuss potential reasons for weakened selective pressure maintaining Mb expression in light of the multiple functions proposed for Mb. Additionally, I discuss results from recent studies exploring the possibility that the loss of Hb and Mb may be advantageous because it reduces the production of reactive oxygen species, levels of oxidized proteins, and the energetic costs associated with replacing oxidatively damaged proteins.
南极鱼类南极鱼科（亚目：南极鱼亚目）中氧结合蛋白血红蛋白（Hb）表达的丧失被认为是一种适应不良现象，由于该科鱼类进化过程中南大洋存在的异常条件，这种现象一直持续存在。心脏心室中细胞内氧结合蛋白肌红蛋白（Mb）表达的丧失则更令人费解，因为它在该科鱼类辐射演化的四个阶段出现，这表明维持该蛋白表达的选择压力减弱。然而，研究表明，Mb存在时会增强功能。在此，我根据Mb所具有的多种功能，讨论维持Mb表达的选择压力减弱的潜在原因。此外，我还讨论了最近一些研究的结果，这些研究探讨了Hb和Mb的丧失可能具有优势的可能性，因为这可以减少活性氧的产生、氧化蛋白的水平以及与替换氧化损伤蛋白相关的能量成本。
