Teets Nicholas M, Gantz J D, Kawarasaki Yuta
Department of Entomology, University of Kentucky, Lexington, KY 40546, USA
Biology Department, Hendrix College, Conway, AK 72032, USA.
J Exp Biol. 2020 Feb 12;223(Pt 3):jeb203448. doi: 10.1242/jeb.203448.
Rapid cold hardening (RCH) is a type of phenotypic plasticity that allows ectotherms to quickly enhance cold tolerance in response to brief chilling (lasting minutes to hours). In this Review, we summarize the current state of knowledge of this important phenotype and provide new directions for research. As one of the fastest adaptive responses to temperature known, RCH allows ectotherms to cope with sudden cold snaps and to optimize their performance during diurnal cooling cycles. RCH and similar phenotypes have been observed across a diversity of ectotherms, including crustaceans, terrestrial arthropods, amphibians, reptiles, and fish. In addition to its well-defined role in enhancing survival to extreme cold, RCH also protects against nonlethal cold injury by preserving essential functions following cold stress, such as locomotion, reproduction, and energy balance. The capacity for RCH varies across species and across genotypes of the same species, indicating that RCH can be shaped by selection and is likely favored in thermally variable environments. Mechanistically, RCH is distinct from other rapid stress responses in that it typically does not involve synthesis of new gene products; rather, the existing cellular machinery regulates RCH through post-translational signaling mechanisms. However, the protective mechanisms that enhance cold hardiness are largely unknown. We provide evidence that RCH can be induced by multiple triggers in addition to low temperature, and that rapidly induced tolerance and cross-tolerance to a variety of environmental stressors may be a general feature of stress responses that requires further investigation.
快速冷硬化（RCH）是一种表型可塑性，它使变温动物能够在受到短暂低温刺激（持续数分钟至数小时）时迅速提高耐寒性。在本综述中，我们总结了关于这一重要表型的当前知识状态，并提供了新的研究方向。作为已知的对温度最快的适应性反应之一，RCH使变温动物能够应对突然的寒流，并在昼夜降温周期中优化其表现。RCH和类似表型已在多种变温动物中观察到，包括甲壳类动物、陆生节肢动物、两栖动物、爬行动物和鱼类。除了在提高对极端寒冷的生存能力方面具有明确作用外，RCH还通过在冷应激后保留基本功能（如运动、繁殖和能量平衡）来防止非致命性冷损伤。RCH的能力在不同物种以及同一物种的不同基因型之间存在差异，这表明RCH可以通过选择塑造，并且在温度多变的环境中可能受到青睐。从机制上讲，RCH与其他快速应激反应不同，因为它通常不涉及新基因产物的合成；相反，现有的细胞机制通过翻译后信号机制调节RCH。然而，增强耐寒性的确切机制在很大程度上尚不清楚。我们提供的证据表明，除了低温外，RCH还可以由多种触发因素诱导，并且对多种环境应激源的快速诱导耐受性和交叉耐受性可能是应激反应的一个普遍特征，需要进一步研究。
