Moderately lower temperatures greatly extend the lifespan of Brachionus manjavacas (Rotifera): Thermodynamics or gene regulation?
Moderately lower temperatures greatly extend the lifespan of Brachionus manjavacas (Rotifera): Thermodynamics or gene regulation?
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DOI：
10.1016/j.exger.2016.02.014
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发表时间：
2016-06
影响因子：
3.9
通讯作者：
Snell TW
中科院分区：
文献类型：
--
作者：
Johnston RK;Snell TW
环境温度极大地影响多种动物的寿命，但这种影响的确切机制仍然很大程度上未知。将温度从 22°C 适度降低至 16°C，可将单角轮虫臂尾轮虫 (Brachionus manjavacas) 的寿命延长高达 163%。新陈代谢的热力学效应有助于延长寿命，但并不是唯一的原因。当轮虫暴露在 16°C 下四天，然后转移到 22°C 时，它们能存活到第 13 天，其存活率与持续保持在 16°C 下的轮虫几乎相同。转移至 22°C 后 9 天仍保持较高的存活率，这表明低温暴露改变了影响衰老速度的基因表达。基因调控效应的相对持久性表明，它在延缓衰老方面可能比热力学效应发挥更大的作用。当暴露发生在生命周期的早期时，这些短期低温处理的延长寿命的效果最大，这证明了早期发育的重要性。将温度降至 16°C 以下至 11°C 或 5°C 没有任何好处。暴露于 16°C 的轮虫还表现出对热、饥饿、氧化和渗透应激的抵抗力增强。 16°C下的繁殖率低于22°C下的繁殖率，但由于它们的繁殖时间更长，因此雌性的终生繁殖力没有显着变化。为了研究哪些基因促成了这些效应，使用 RNAi 敲低了特定温度传感基因的表达。在测试的 12 个基因中，其中 4 个基因的 RNAi 敲低消除了四天冷处理的生存增强作用：TRP7、叉头盒 C、Y 盒因子和核糖体蛋白 S6。这表明活跃的基因调控是温度介导的寿命延长的重要因素，并且这些特定基因在这些途径中发挥着不可或缺的作用。作为一种热敏传感器，TRP7 可能负责触发信号级联，从而促进温度介导的寿命延长。 TRP 基因还可能为能够模拟低温暴露影响的靶向基因操作或药理干预提供特别有前途的候选者。这些结果支持了最新的衰老理论，即衰老速度是由主动调节的遗传机制决定的，而不是分子损伤的累积。
Environmental temperature greatly affects lifespan in a wide variety of animals, but the exact mechanisms underlying this effect are still largely unknown. A moderate temperature decrease from 22°C to 16°C extends the lifespan of the monogonont rotifer Brachionus manjavacas by up to 163%. Thermodynamic effects on metabolism contribute to this increase in longevity, but are not the only cause. When rotifers are exposed to 16°C for four days and then transfered to 22°C, they survive until day 13 at nearly identical rates as rotifers maintained at 16°C continuously. This persistence of the higher survival for nine days after transfer to 22°C suggests that low temperature exposure alters the expression of genes that affect the rate of aging. The relative persistence of the gene regulation effect suggests that it may play an even larger role in slowing aging than the thermodynamic effects. The life extending effects of these short-term low temperature treatments are largest when the exposure happens early in the life cycle, demonstrating the importance of early development. There is no advantage to lowering the temperature below 16°C to 11° or 5°C. Rotifers exposed to 16°C also displayed increased resistance to heat, starvation, oxidative and osmotic stress. Reproductive rates at 16°C were lower than those at 22°C, but because they reproduce longer, there is no significant change in the lifetime fecundity of females. To investigate which genes contribute to these effects, the expression of specific temperature sensing genes was knocked down using RNAi. Of 12 genes tested, RNAi knockdown of four eliminated the survival enhancing effects of the four-day cold treatment: TRP7, forkhead box C, Y-box factor, and ribosomal protein S6. This demonstrates that active gene regulation is an important factor in temperature mediated life extension, and that these particular genes play an integral role in these pathways. As a thermoresponsive sensor, TRP7 may be responsible for triggering the signaling cascade contributing to temperature mediated life extension. The TRP genes may also provide especially promising candidates for targeted gene manipulations or pharmacological interventions capable of mimicking the effects of low temperature exposure. These results support recent theories of aging that claim rate of aging is determined by an actively regulated genetic mechanism rather than an accumulation of molecular damage.