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A worm has been revived after 46,000 years in the Siberian permafrost
Scientists have revived a worm that was frozen 46,000 years ago — at a time when woolly mammoths, sabre-toothed tigers and giant elks still roamed the Earth.
The roundworm, of a previously unknown species, survived 40 meters (131.2 feet) below the surface in the Siberian permafrost in a dormant state known as cryptobiosis, according to Teymuras Kurzchalia, professor emeritus at the Max Planck Institute of Molecular Cell Biology and Genetics in Dresden and one of the scientists involved in the research.
Organisms in a cryptobiotic state can endure the complete absence of water or oxygen and withstand high temperatures, as well as freezing or extremely salty conditions. They remain in a state “between death and life,” in which their metabolic rates decrease to an undetectable level, Kurzchalia explained.
“One can halt life and then start it from the beginning. This a major finding,” he said, adding that other organisms previously revived from this state had survived for decades rather than millennia.
Five years ago, scientists from the Institute of Physicochemical and Biological Problems in Soil Science in Russia found two roundworm species in the Siberian permafrost.
One of the researchers, Anastasia Shatilovich, revived two of the worms at the institute by simply rehydrating them with water, before taking around 100 worms to labs in Germany for further analysis, transporting them in her pocket.
After thawing the worms, the scientists used radiocarbon analysis of the plant material in the sample to establish that the deposits had not been thawed since between 45,839 and 47,769 years ago.
But still, they didn’t know whether the worm was a known species. Eventually, genetic analysis conducted by scientists in Dresden and Cologne showed that these worms belonged to a novel species, which researchers named Panagrolaimus kolymaenis.
Researchers also found that the P. kolymaenis shared with C. elegans — another organism often used in scientific studies — “a molecular toolkit” that could allow it to survive cryptobiosis. Both organisms produce a sugar called trehalose, possibly enabling them to endure freezing and dehydration.
“To see that the same biochemical pathway is used in a species which is 200, 300 million years away, that’s really striking,” said Philipp Schiffer, research group leader of the Institute of Zoology at the University of Cologne and one of the scientists involved in the study. “It means that some processes in evolution are deeply conserved.”
And, Schiffer added, there are other actionable insights which can be gleaned by studying these organisms.
“By looking at and analyzing these animals, we can maybe inform conservation biology, or maybe even develop efforts to protect other species, or at least learn what to do to protect them in these extreme conditions that we have now,” he told CNN.
注释：
revive: v
表示"复生"，means " bring back to consciousness"，如：We tried to revive him but without avail. 我们试图使他苏醒,但没有成功。
sabre-toothed: adj
表示"长着锐利的长犬牙的"，means "having teeth that resemble sabers;"，如：They realise that, ironically, it is the distinctive teeth that will bring about the Sabre Tooth's downfall. 剑齿虎是生于古时的猫科类动物，标记是具有超长的犬齿。
elk: n
表示" 麋；驼鹿；"，means "large northern deer with enormous flattened antlers in the male; called `elk' in Europe and `moose' in North America"，如：But when they looked only to their footing, they did not see the elk. 然而当他们只顾注意自己的脚步时，却看不到麋了。
cryptobiosis: n
表示" [生]隐生(现象)；潜生(现象)"，means "a state in which an animal's metabolic activities come to a reversible standstill"，如：Although I have said that the water bear does not undergo any form of metabolism during cryptobiosis, it actually has a metabolic rate of 0.1%, rendering it almost dead, but yet, not dead. 尽管我刚才说过水熊在隐生状态下没有新陈代谢，实际上它还是有0.;1%25的新陈代谢，表现出来的状态是假死状态，而不是真正的死亡状态。
cryptobiotic: adj
表示"隐生的"，means "of or related to the state of cryptobiosis"，如：The Tardigrade is almost dead in the cryptobiotic stage, other than the fact that it can revive itself from this state. 缓步动物门在隐生阶段几乎是处于死亡状态，除非它自己苏醒过来。
rehydrate: v
表示"〈化〉使 水化；补充体液"，如：Keep a bottle of water or a rehydrating freshener on your desk at work. Use it to freshen you up during the long day. 工作时,在办公桌上放一瓶水或一瓶再化合清凉剂,用于提神。
radiocarbon: n
表示" 放射性炭"，如：The material in this beach has been dated by radiocarbon. 这个海滩上的物质经过放射性碳测定。
trehalose: n
表示"[化]海藻糖"，如：Trehalose is a kind of preservative agent which has potential application.海藻糖是一种具有广阔应用前景的生物保护剂。
glean: v
表示" 拾落穗；收集"，means "gather, as of natural products;"，如：What useful thing can you glean from that?哪些有益的事情你能收集到的？
中文简要说明：
科幻电影中，人类进入冬眠舱沉睡数百年，醒来后已身在另一个时空，这种「为生命按下暂停键」的能力，已经出现在动物身上。德国和俄罗斯研究团队最近发表研究，指出在西伯利亚永冻层出土的线虫（roundworm），在地底待了4万6千年后，经过「解冻」过程竟然奇迹复活！透过研究牠们的基因，科学家期盼能找出保育物种的方式，甚至强化人类的生存韧性。
根据CNN、《纽约邮报》报导，科学家指出，这些线虫来自永冻层表土下40公尺，已经沉睡了4万6千年，与牠们同期的动物包含长毛象、剑齿虎和巨驼鹿，现在都已经绝迹。
这么多年来，线虫的生命都处于「隐生」（cryptobiosis）的状态，也就是生命为了应付极端环境，将新陈代谢降低到极致，进入了一种介于生与死之间的灰色地带。
更令人讶异的是，这些过去被认为灭绝的线虫，苏醒后不仅适应良好，能顺利存活，还在科学家的协助下繁殖了100代。
研究显示，这种线虫似乎能产生一种海藻糖（trehalose），有助于保护细胞，让牠们在寒冷、缺水的条件下存活。
科学家认为，透过了解这些动物的基因组，或许能帮助我们保育濒危物种，甚至用来提升人类适应环境的能力。这项研究已发表在国际期刊《公共科学图书馆：遗传学》（PLOS Genetics）。
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