Ramløv H
Department of Life Sciences and Chemistry, Roskilde University, Denmark.
Hum Reprod. 2000 Dec;15 Suppl 5:26-46. doi: 10.1093/humrep/15.suppl_5.26.
Polar, alpine and temperate ectothermic (cold-blooded) animals encounter temperatures below the melting point of their body fluids either diurnally or seasonally. These animals have developed a number of biochemical and physiological adaptations to survive the low temperatures. The problems posed to the animals during cold periods include changes in membrane and protein structure due to phase changes in these molecules, changes in electrolyte concentrations and other solutes in the body fluids as well as changes in metabolism. Cold-tolerant ectothermic animals can be divided into two groups depending which of two 'strategies' they employ to survive the low temperatures: freeze-tolerant animals which survive ice formation in the tissues and freeze-avoiding animals which tolerate the low temperatures but not crystallization of the body fluids. The adaptations are mainly directed towards the control or avoidance of ice formation and include the synthesis of low mol. wt cryoprotectants, ice-nucleating agents and antifreeze proteins. However, some of the adaptations such as the synthesis of low mol. wt cryoprotectants are also more specific in their mechanism, e.g. direct stabilizing interaction with membranes and proteins. The mechanisms employed by such animals may offer ideas and information on alternative approaches which might be usefully employed in the cryopreservation of cells and tissues frequently required in assisted reproductive technology.
极地、高山和温带的变温（冷血）动物在白天或季节中会遇到低于其体液熔点的温度。这些动物已经发展出许多生化和生理适应性变化以在低温环境中生存。寒冷时期给动物带来的问题包括由于这些分子的相变导致的膜和蛋白质结构变化、体液中电解质浓度和其他溶质的变化以及新陈代谢的变化。耐寒变温动物可根据它们采用两种“策略”中的哪一种来在低温下生存而分为两组：耐冻动物能够在组织中形成冰的情况下存活，而避冻动物能够耐受低温但体液不会结晶。这些适应性变化主要针对控制或避免冰的形成，包括合成低分子量的冷冻保护剂、冰核剂和抗冻蛋白。然而，一些适应性变化，如低分子量冷冻保护剂的合成，在其机制上也更具特异性，例如与膜和蛋白质的直接稳定相互作用。这类动物所采用的机制可能会为辅助生殖技术中经常需要的细胞和组织冷冻保存提供有用的替代方法的思路和信息。
