从最古老DNA中窥见郁郁葱葱的北极(中)
日期:2022-12-16 12:24

(单词翻译:单击)

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Along the way, the researchers tweaked their methods for extracting DNA from ancient samples and upgraded the machines they used to sequence it.

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在此过程中,研究人员调整了从古代样本中提取DNA的方法,并升级了用来对其测序的机器=B_tU%#G;~QI&

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As they became better at fishing for genes, they would take out more of the Kap Kobenhavn samples for another shot.

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随着他们在寻找基因方面更得心应手,他们从Kap Kobenhavn样本中取出更多的样本进行另一次尝试|707WL#n1Y

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But for years they failed, again and again.

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但多年来,他们一次又一次地失败q3q^rS!#KaDv-1tU

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From time to time they were tantalized by what looked like short bits of DNA, which are called reads.

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时不时地,他们被看起来像短小DNA片段的物质所戏弄,这些物质叫读长_HW(N&-qyYNyDdYFD

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The researchers couldn’t rule out the possibility that bits of young DNA in Greenland, or even in their lab, had contaminated the reads.

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研究人员不能排除格陵兰岛的年轻DNA片段,甚至是他们实验室的DNA片段已经污染了读长的可能性*crQWC09waB8!uOD

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Finally, after a major upgrade in their technology, they found DNA in the samples in 2017.

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最后,在他们的技术进行了重大升级后,他们在2017年的样本中发现了DNAiqdIY_ccvp][

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The permafrost turned out to be loaded with genetic material.

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这些永久冻土层中原来含有大量遗传物质CX=#uRmE~SOi~vMu)^

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Before long they had collected millions of DNA fragments.

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不久,他们就收集了数百万个DNA片段f,b+[n7mN,cwA[rk

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“It was a breakthrough,” Dr. Willerslev said. “It was going from nothing or very little that you don’t know is real, to suddenly: It’s there.”

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“这是一个突破,”威勒斯列夫博士说,“从你不知道是真的什么都没有或很少,突然变成了:它就在那里.HZZft,=YKqO。”

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The researchers lined up the fragments with DNA sequences of living species to figure out where they belonged on the evolutionary tree.

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研究人员将这些片段与现存物种的DNA序列比对,以确定它们在进化树上的位置+#u5Xls%H=#Urk

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They found 102 different kinds of plants — including 78 that had previously been identified from fossils and 24 new ones.

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他们发现了102种不同的植物,其中包括78种以前从化石中发现的植物和24种新的植物SE&R2Lxh-vdT|Ens

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The plant DNA painted a picture of forests dominated by poplar and birch trees.

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植物DNA描绘了一幅以白杨树和白桦树为主的森林图景8WC^,%QGZzh7T#

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Other sequences come from land animals, including caribou, hares, mastodons, geese, lemmings and ants.

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其他序列来自陆地动物,包括驯鹿、野兔、乳齿象、鹅、旅鼠和蚂蚁ePxgh^ycgL^d70FEhi

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The researchers also found marine species, such as horseshoe crabs, corals and algae.

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研究人员还发现了海洋物种,如马蹄蟹、珊瑚和藻类3h~TXG9=N!Ys|u~cLLKX

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“It superseded everything we imagined,” Dr. Kjaer said.

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“它取代了我们之前想象的一切cJ=iTBW[TT+[AMO|UJ。”克亚博士说Co_zSTLklb,4oI.H

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The researchers also searched the permafrost for new clues to the age of the fossils.

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研究人员还在永久冻土层中寻找化石年代的新线索Aj80+21tNOqo

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They found layers in the sediment in which the minerals revealed that the Earth’s magnetic field had flipped.

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他们在沉积物中发现了几层矿物质,揭示地球磁场曾经发生了翻转)!C@gbC@vX-

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The age of those reversals helped the researchers determine that Kap Kobenhavn was at least two million years old, but they could not establish a clear upper limit.

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这些逆转的年代帮助研究人员确定,Kap Kobenhavn至少有200万岁,但他们无法确定一个明确的上限!i_~Z0h.hr+ism

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“My gut feeling as a geoscientist is that it’s older,” Dr. Kjaer said.

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“作为一名地球科学家,我的直觉是它还要更加古老|MbbC_Nl0ZX_aB&Ei6w。”克亚博士说%Gh%XIX|[1@*M+,6&Mq|

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The researchers ruled out the possibility that the DNA came from younger species that contaminated the older permafrost.

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研究人员排除了这些DNA来自较年轻的物种,而这些物种污染了较古老的永久冻土的可能性5(CFV;Y~uYL]=

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The DNA of the birch trees lacked many of the mutations that living species have, indicating that they were ancient.

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白桦树的DNA缺乏许多现存物种所具有的突变,这表明它们是古老的OE0Kv0tiWmh!0%

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The DNA also had a distinct pattern of damage that occurs only when the molecules have been sitting in sediment for geological stretches of time.

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这些DNA也有一种明显的损伤模式,只有当分子在沉积物中停留几段地质时期才会发生6bc-ORPMwv;

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“It really helps show that this really is old DNA,” said Tyler Murchie, a postdoctoral researcher at McMaster University who was not involved in the new study.

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没有参与这项新研究的麦克马斯特大学博士后研究员泰勒·默奇说:“这真的有助于证明这确实是古老的DNA|(6sCJB4-Lw。”

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