Department of Bioscience, Aarhus University, 8000 Aarhus C, Denmark.
J Exp Biol. 2012 Oct 1;215(Pt 19):3403-10. doi: 10.1242/jeb.073726. Epub 2012 Jun 12.
Whales show an exceptionally wide range of diving capabilities and many express high amounts of the O(2) carrier protein myoglobin (Mb) in their muscle tissues, which increases their aerobic diving capacity. Although previous studies have mainly focused on the muscle Mb concentration and O(2) carrying capacity as markers of diving behavior in whales, it still remains unexplored whether whale Mbs differ in their O(2) affinities and nitrite reductase and peroxidase enzymatic activities, all functions that could contribute to differences in diving capacities. In this study, we have measured the functional properties of purified Mbs from five toothed whales and two baleen whales and have examined their correlation with average dive duration. Results showed that some variation in functional properties exists among whale Mbs, with toothed whale Mbs having higher O(2) affinities and nitrite reductase activities (similar to those of horse Mb) compared with baleen whale Mbs. However, these differences did not correlate with average dive duration. Instead, a significant correlation was found between whale Mb concentration and average duration and depth of dives, and between O(2) affinity and nitrite reductase activity when including horse Mb. Despite the fact that the functional properties showed little species-specific differences in vitro, they may still contribute to enhancing diving capacity as a result of the increased muscle Mb concentration found in extreme divers. In conclusion, Mb concentration rather than specific functional reactivities may support whale diving performance.
鲸鱼表现出异常广泛的潜水能力，它们的肌肉组织中含有大量的氧载体蛋白肌红蛋白 (Mb)，这增加了它们的有氧潜水能力。尽管之前的研究主要集中在肌肉 Mb 浓度和氧携带能力作为鲸鱼潜水行为的标志物上，但鲸鱼 Mb 在氧亲和力和亚硝酸盐还原酶和过氧化物酶活性方面是否存在差异仍未得到探索，所有这些功能都可能有助于潜水能力的差异。在这项研究中，我们测量了来自五种齿鲸和两种须鲸的纯化 Mb 的功能特性，并研究了它们与平均潜水持续时间的相关性。结果表明，鲸鱼 Mb 的功能特性存在一些差异，齿鲸 Mb 的氧亲和力和亚硝酸盐还原酶活性较高（与马 Mb 相似），而须鲸 Mb 则较低。然而，这些差异与平均潜水持续时间没有相关性。相反，当包括马 Mb 时，在 Mb 浓度与潜水持续时间和深度之间以及氧亲和力和亚硝酸盐还原酶活性之间发现了显著的相关性。尽管在体外，功能特性显示出很少的物种特异性差异，但由于在极端潜水者中发现的肌肉 Mb 浓度增加，它们仍可能有助于增强潜水能力。总之，Mb 浓度而不是特定的功能反应性可能支持鲸鱼的潜水表现。
