da Mota Araujo Helena Rachel, Sartori Marina Rincon, Navarro Claudia D C, de Carvalho José Eduardo, Luis da Cruz André
Instituto de Biologia, Universidade Federal da Bahia, Campus Ondina, 40170-115 Salvador, Bahia, Brazil.
Departamento de Patologia, Faculdade de Ciências Médicas, Universidade Estadual de Campinas, 13083-877, São Paulo, Brazil.
J Exp Biol. 2021 Nov 1;224(21). doi: 10.1242/jeb.243142. Epub 2021 Nov 5.
Snakes are interesting examples of taxa that can overcome energy metabolism challenges, as many species can endure long periods without feeding, and their eventual meals are of reasonably large sizes, thus exhibiting dual extreme adaptations. Consequently, metabolic rate increases considerably to attend to the energetic demand of digestion, absorption and protein synthesis. These animals should be adapted to transition from these two opposite states of energy fairly quickly, and therefore we investigated mitochondrial function plasticity in these states. Herein, we compared liver mitochondrial bioenergetics of the boid snake Boa constrictor during fasting and after meal intake. We fasted the snakes for 60 days, and then we fed a subgroup with 30% of their body size and evaluated their maximum postprandial response. We measured liver respiration rates from permeabilized tissue and isolated mitochondria. From isolated mitochondria, we also measured Ca2+ retention capacity and redox status. Mitochondrial respiration rates were maximized after feeding, reaching an approximately 60% increase from fasting levels when energized with complex I-linked substrates. Interestingly, fasting and fed snakes exhibited similar respiratory control ratios and citrate synthase activity. Furthermore, we found no differences in Ca2+ retention capacity, indicating no increase in susceptibility to mitochondrial permeability transition, and no changes in mitochondrial redox state, although fed animals exhibited increases in the release of H2O2. Thus, we conclude that liver mitochondria from B. constrictor snakes increase respiration rates during the postprandial period and quickly improve the bioenergetic capacity without compromising redox balance.
蛇是能够克服能量代谢挑战的有趣类群实例，因为许多蛇种可以长时间不进食，而且它们最终的食物量相当大，因此展现出双重极端适应性。因此，代谢率会大幅提高以满足消化、吸收和蛋白质合成的能量需求。这些动物应该能够相当迅速地适应从这两种相反能量状态的转变，所以我们研究了这些状态下的线粒体功能可塑性。在此，我们比较了王蛇在禁食期间和进食后的肝脏线粒体生物能量学。我们让蛇禁食60天，然后给一组蛇投喂其体重30%的食物，并评估它们餐后的最大反应。我们测量了通透组织和分离线粒体的肝脏呼吸速率。从分离的线粒体中，我们还测量了钙离子保留能力和氧化还原状态。进食后线粒体呼吸速率达到最大值，当用与复合体I相关的底物供能时，比禁食水平提高了约60%。有趣的是，禁食和进食的蛇表现出相似的呼吸控制率和柠檬酸合酶活性。此外，我们发现钙离子保留能力没有差异，表明线粒体通透性转换的易感性没有增加，线粒体氧化还原状态也没有变化，尽管进食的动物过氧化氢释放量有所增加。因此，我们得出结论，王蛇的肝脏线粒体在餐后时期呼吸速率增加，并能迅速提高生物能量能力而不影响氧化还原平衡。
