The efficient production of energy via oxidative phosphorylation is essential to the growth, survival, and reproduction of eukaryotes. The behavior (position of, and communication between, mitochondria) and morphology of mitochondria play key roles in efficient energy production and are influenced by oxidative stressors such as ultraviolet (UV) radiation. We tested the hypothesis that mitochondria change their behavior and morphology to meet energetic demands of responding to changes in oxidative stress. Specifically, we predicted that UV irradiation would increase the density of inner mitochondrial membrane and proportion of inter-mitochondrial junctions to influence whole-animal metabolic rate. Using transmission electron microscopy, we found that both three and six hours of UV-A/B irradiation (0.5 W/m2) increased the proportion of inter-mitochondrial junctions (with increasing mitochondrial aspect ratio) and the density of inner mitochondrial membrane in myocytes of Tigriopus californicus copepods. Mitochondrial density increased following both irradiation treatments, but mitochondrial size decreased under the six hour treatment. Metabolic rate was maintained under three hours of irradiation but decreased following six hours of exposure. These observations demonstrate that the density of inner mitochondrial membrane and proportion of inter-mitochondrial junctions can play formative roles in maintaining whole-animal metabolic rate, and ultimately organismal performance, under exposure to an oxidative stressor.

中文翻译：

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紫外线照射改变桡足类肌细胞线粒体内膜的密度和线粒体间连接的比例

通过氧化磷酸化有效产生能量对真核生物的生长、存活和繁殖至关重要。线粒体的行为（线粒体的位置和通讯）和线粒体的形态在有效的能量生产中起着关键作用，并受到紫外线 (UV) 辐射等氧化应激源的影响。我们测试了线粒体改变其行为和形态以满足响应氧化应激变化的能量需求的假设。具体来说，我们预测紫外线照射会增加线粒体内膜的密度和线粒体间连接的比例，从而影响整个动物的代谢率。使用透射电子显微镜，我们发现 3 小时和 6 小时的 UV-A/B 照射（0. 5 W/m2）增加了虎足虎足类肌细胞线粒体间连接的比例（随着线粒体纵横比的增加）和线粒体内膜的密度。两种辐射处理后线粒体密度均增加，但六小时处理后线粒体大小减小。代谢率在照射 3 小时后保持不变，但在照射 6 小时后下降。这些观察结果表明，在暴露于氧化应激源的情况下，线粒体内膜的密度和线粒体间连接的比例可以在维持整个动物的代谢率和最终的机体性能方面发挥形成作用。