Molecular Cloning and Evolutionary Analysis of Hemoglobin α-Chain Genes in Bats

Abstract

Bats are the only mammals with the capacity for powered flight. When flying, they need abundant energy and oxygen. According to previous works, the hemoglobin (Hb) oxygen loading function of bats is insensitive to variations in body temperature, although different bat species have different heat sensitivity. We cloned Hb alpha-chain sequences from eight bat species to investigate whether they have different characteristics. We found that Hb in the bat lineages is under purifying selection, which accords with the importance of its function in bats. Three turn regions in bat Hb, however, have distinct evolutionary rates compared with those of other mammals, and the codons in these regions have an accelerated rate of evolution. These codons are under divergent selection in bats. These changes in Hb may have occurred in response to the physiological requirements of the species concerned, as adaptations to different lifestyles.

Hemoglobins and High-altitude Adaptive Evolution in Vertebrates

“…以上特征决定了即使需氧范围是哺乳类的两 倍 [91] , 鸟类的海拔分布范围仍然有较大差异 [88] , 因 此成为内温动物高海拔低氧适应进化的典型最适研 究对象 [64,92,93] . 此外, 鸟类在飞行中在保证摄入和传 输足够氧的同时组织能量会急剧增加, 空中飞行时 能量会增加至海平面静息状态的 15 倍 [94] , 能量代谢 是 Hbs 正常执行功能的基础 [95] , 血液氧运输和需氧 能量代谢共同作用形成鸟类和哺乳类适应飞行的动 力 [96,97] . 鸟类和哺乳类动物低氧适应的一般生理适 应和比较生理学机制是进一步细胞和分子机制研究 的背景资料.…”