A Low Temperature Limit for Life on Earth.
A Low Temperature Limit for Life on Earth.
复制标题
地球生命的低温限制。
DOI：
10.1371/journal.pone.0066207
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发表时间：
2013
期刊：
影响因子：
3.7
通讯作者：
Price HC
中科院分区：
文献类型：
--
作者：
Clarke A;Morris GJ;Fonseca F;Murray BJ;Acton E;Price HC
地球上生命的温度下限没有普遍接受的值。我们提出的经验证据表明，在外部冰存在的情况下冷却的自由生活微生物细胞将在-10°C至-26°C之间的温度下经历冷冻诱导的干燥和玻璃化转变（玻璃化）。与细胞内冷冻相反，玻璃化冷冻不会导致死亡，并且细胞一旦玻璃化可以在非常低的温度下存活。玻璃化后的高内部粘度意味着氧气和代谢物的扩散减慢到细胞代谢停止的程度。细胞内玻璃化的温度范围使得该过程对于自由生活的微生物具有基本的生态意义。只有在不存在细胞外冰的情况下，细胞才能在低于这些温度的情况下继续代谢，云中的水滴提供了这种栖息地的重要例子。在多细胞生物中，细胞与环境中的冰隔离，决定它们如何响应低温的主要因素是细胞外液的物理状态。当这种液体冻结时，细胞将以类似于自由生活的微生物的方式脱水和玻璃化。当细胞外液过冷时，细胞可以继续代谢（尽管缓慢），温度低于自由生活微生物的玻璃化温度。有证据表明，这些细胞最终也会玻璃化，但温度可能低于 -50°C。由于细胞必须恢复到流体状态才能恢复新陈代谢并完成其生命周期，而冰几乎普遍存在于零度以下的环境中，因此我们认为玻璃化温度代表了地球上生命的普遍较低的热极限，尽管其精确值在单细胞生物（通常高于-20°C）和多细胞生物（通常低于-20°C）之间有所不同。然而，很少有多细胞生物能够在低于~−2°C 的温度下完成其生命周期。
There is no generally accepted value for the lower temperature limit for life on Earth. We present empirical evidence that free-living microbial cells cooling in the presence of external ice will undergo freeze-induced desiccation and a glass transition (vitrification) at a temperature between −10°C and −26°C. In contrast to intracellular freezing, vitrification does not result in death and cells may survive very low temperatures once vitrified. The high internal viscosity following vitrification means that diffusion of oxygen and metabolites is slowed to such an extent that cellular metabolism ceases. The temperature range for intracellular vitrification makes this a process of fundamental ecological significance for free-living microbes. It is only where extracellular ice is not present that cells can continue to metabolise below these temperatures, and water droplets in clouds provide an important example of such a habitat. In multicellular organisms the cells are isolated from ice in the environment, and the major factor dictating how they respond to low temperature is the physical state of the extracellular fluid. Where this fluid freezes, then the cells will dehydrate and vitrify in a manner analogous to free-living microbes. Where the extracellular fluid undercools then cells can continue to metabolise, albeit slowly, to temperatures below the vitrification temperature of free-living microbes. Evidence suggests that these cells do also eventually vitrify, but at lower temperatures that may be below −50°C. Since cells must return to a fluid state to resume metabolism and complete their life cycle, and ice is almost universally present in environments at sub-zero temperatures, we propose that the vitrification temperature represents a general lower thermal limit to life on Earth, though its precise value differs between unicellular (typically above −20°C) and multicellular organisms (typically below −20°C). Few multicellular organisms can, however, complete their life cycle at temperatures below ∼−2°C.
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DOI：
10.1098/rsta.2002.1141
发表时间：
2003-03-15
期刊：
PHILOSOPHICAL TRANSACTIONS OF THE ROYAL SOCIETY OF LONDON SERIES A-MATHEMATICAL PHYSICAL AND ENGINEERING SCIENCES
影响因子：
--
作者：
Franks, F
通讯作者：
Franks, F
DOI：
10.1016/j.cbpa.2011.05.032
发表时间：
2011-10-01
影响因子：
2.3
作者：
Hengherr, Steffen;Schill, Ralph O.;Clegg, J. S.
通讯作者：
Clegg, J. S.
影响因子：
44.1
作者：
Bartels-Rausch, Thorsten;Bergeron, Vance;Uras-Aytemiz, Nevin
通讯作者：
Uras-Aytemiz, Nevin
影响因子：
4.1
作者：
Goyal, K;Walton, LJ;Tunnacliffe, A
通讯作者：
Tunnacliffe, A
DOI：
10.1016/s0740-0020(89)80021-8
发表时间：
1989-01-01
期刊：
Food Microbiology (London)
影响因子：
--
作者：
COLLINS M A;BUICK R K
通讯作者：
BUICK R K