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首页> 外文期刊>American Journal of Physiology >Multiple strategies of Lake Victoria cichlids to cope with lifelong hypoxia include hemoglobin switching.
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Multiple strategies of Lake Victoria cichlids to cope with lifelong hypoxia include hemoglobin switching.

机译：维多利亚湖丽鱼科植物应对终身缺氧的多种策略包括血红蛋白转换。

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摘要

Many fish species adapt to hypoxia by reducing their metabolic rate and increasing hemoglobin-oxygen (Hb-O(2)) affinity. Pilot studies with young broods of cichlids showed that the young could survive severe hypoxia in contrast with the adults. It was therefore hypothesized that early exposure results in improved oxygen transport. This hypothesis was tested using split brood experiments. Broods of Astatoreochromis alluaudi, Haplochromis ishmaeli, and a tilapia hybrid (Oreochromis) were raised either under normoxia (NR; 80-90% air saturation) or hypoxia (HR; 10% air saturation). The activity of the mitochondrial citrate synthase was not different between NR and HR tilapia, but was significantly decreased in HR A. alluaudi and H. ishmaeli, indicating lowered maximum aerobic capacities. On the other hand, hemoglobin and hematocrit levels were significantly higher in all HR fish of the three species, reflecting a physiological adaptation to safeguard oxygen transport capacity. In HR tilapia, intraerythrocytic GTP levels were decreased, suggesting an adaptive increase of blood-O(2) affinity. Similar changes were not found in HR H. ishmaeli. In this species, however, all HR specimens exhibited a distinctly different iso-Hb pattern compared with their NR siblings, which correlated with a higher intrinsic Hb-O(2) affinity in the former. All HR cichlids thus reveal left-shifted Hb-O(2) equilibrium curves, mediated by either decreased allosteric interaction or, in H. ishmaeli, by the production of new hemoglobins. It is concluded that the adaptation to lifelong hypoxia is mainly due to improved oxygen transport.
机译：许多鱼类通过降低其代谢率和增加血红蛋白氧（Hb-O（2））亲和力来适应缺氧。对丽鱼科鱼幼体进行的试验研究表明，与成虫相比，幼体可以在严重的缺氧条件下生存。因此，假设早期接触可改善氧气的运输。使用分裂育雏实验检验了该假设。在常氧（NR; 80-90％空气饱和度）或低氧（HR; 10％空气饱和度）的条件下，饲养了Astatoreochromis alluaudi，Haplochromis ishmaeli和罗非鱼杂种（Oreochromis）的幼体。 NR和H​​R罗非鱼之间的线粒体柠檬酸合酶活性没有差异，但是在HR A. alluaudi和H. ishmaeli中明显降低，表明最大有氧能力降低。另一方面，在这三个物种的所有HR鱼中，血红蛋白和血细胞比容水平均显着较高，这反映了生理上的适应性，以维持氧气的运输能力。在HR罗非鱼中，erythrrocytic GTP水平降低，表明血液O（2）亲和力的适应性增加。在HR H. ishmaeli中未发现类似的变化。然而，在这个物种中，所有HR标本与其NR兄弟姐妹相比都表现出明显不同的iso-Hb模式，这与前者中更高的固有Hb-O（2）亲和力相关。因此，所有的HR丽鱼科鱼都揭示了左移的Hb-O（2）平衡曲线，该曲线由变构相互作用的减少或在H.ishmaeli中由新血红蛋白的产生介导。结论是，适应终生缺氧的主要原因是改善了氧气的运输。

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