緩步動(dòng)物幾乎堅(jiān)不可摧的4個(gè)原因

緩步動(dòng)物幾乎堅(jiān)不可摧的4個(gè)原因

Tardigrades are microscopic animals blessed with two very cool nicknames — the water bear and the moss piglet. They are segmented and reach a maximum length of a millimeter, maybe a millimeter and a half.

緩步動(dòng)物是顯微鏡下的動(dòng)物，它們有兩個(gè)非?？岬木b號(hào)——水熊和苔蘚小豬。它們被分割，最大長(zhǎng)度為一毫米，也許是一毫米半。

Water bears are as seemingly indestructible as they are tiny. They've been known to survive in extreme temperatures, though there are limits. (We'll get to that in a minute.) They shrug off extreme doses of radiation and laugh in the face of the silent vacuum of space itself. In one experiment, water bears were exposed to outer space for 10 days. After returning to Earth, it was discovered that many of the bears had survived and some even had babies.

水熊看起來(lái)是堅(jiān)不可摧的，因?yàn)樗鼈兒苄?。它們能在極端的溫度下生存，雖然也有極限。(我們馬上就會(huì)講到。)它們對(duì)高劑量的輻射一笑置之，對(duì)空間本身的寂靜真空一笑置之。在一項(xiàng)實(shí)驗(yàn)中，水熊暴露在外太空10天。回到地球后，人們發(fā)現(xiàn)許多北極熊幸存了下來(lái)，有些甚至還生了孩子。

Tardigrades can survive temperature extremes, space and even radiation. (Photo: Schokraie E, Warnken U, Hotz-Wagenblatt A, Grohme MA, Hengherr S, et al. (2012) [CC BY 2.5]/Wikimedia Commons)

Scientists even tried to rid the planet of tardigrades (only in theory) by putting the creatures through a series of tests that mimicked what they would experience if a deadly asteroid or radiation burst hit the Earth. But the tardigrades shrugged that off, too, outlasting billions of years worth of theoretic disaster events, according to a study published in the journal Scientific Reports.

科學(xué)家們甚至試圖通過(guò)讓這些生物進(jìn)行一系列測(cè)試，模擬它們?cè)谥旅男⌒行腔蜉椛浔l(fā)襲擊地球時(shí)的感受，從而(僅在理論上)消除地球上的緩步動(dòng)物。但根據(jù)發(fā)表在《科學(xué)報(bào)告》雜志上的一項(xiàng)研究，這些緩步動(dòng)物也對(duì)這種說(shuō)法不屑一顧，它們經(jīng)歷了數(shù)十億年的理論災(zāi)難事件。

They may be alive on the moon

它們可能在月球上還活著

The moon has craters and mountains and other nooks and crannies where tardigrades could survive. (Photo: NASA's Goddard Space Flight Center Scientific Visualization Studio [CC BY 2.0]/Flickr)

Most recently, the little-water-bears-that-could caught our attention because they were revealed to be the only possible survivors from a 2019 crash landing on the moon. Luckily, the Israeli Beresheet probe didn't have any other living cargo on board when it crashed in April — a failed attempt to become the first private spacecraft to land on the moon.

最近，這些小水熊引起了我們的注意，因?yàn)樗鼈儽话l(fā)現(xiàn)是2019年月球撞擊事件中唯一可能的幸存者。幸運(yùn)的是，今年4月墜毀的以色列“貝雷希特”號(hào)探測(cè)器上沒(méi)有其他任何活著的貨物。這架探測(cè)器試圖成為第一個(gè)登上月球的私人宇宙飛船，但以失敗告終。

However, a few thousand of the creatures were onboard at the time. They were part of a tiny lunar library put together by the Arch Mission Foundation, a group whose goal is to find a backup for Earth. The library consisted of the tardigrades, 30 million pages of information and human DNA samples.

然而，當(dāng)時(shí)船上有幾千只這種生物。它們是由Arch任務(wù)基金會(huì)建立的小型月球圖書館的一部分，該基金會(huì)的目標(biāo)是為地球找到一個(gè)備份。圖書館包括緩步動(dòng)物，3000萬(wàn)頁(yè)的信息和人類DNA樣本。

They can survive without water

沒(méi)有水它們也能生存

Despite their nickname, water bears can go without water for about 10 years, living as a dried-out shell. For 250 years, we had no idea how these tiny creatures survived this extreme drying out, but a group of researchers from University of North Carolina at Chapel Hill discovered an answer.

盡管它們外號(hào)是水熊，但它們可以在沒(méi)有水的情況下生活大約10年，就像一個(gè)干涸的殼一樣。250年來(lái)，我們一直不知道這些微小的生物是如何在極度干燥的環(huán)境下生存下來(lái)的，但來(lái)自北卡羅來(lái)納大學(xué)教堂山分校的一組研究人員找到了答案。

Researchers dried out tardigrades to see which genes turned on as a response to the stress, according to their study published in Molecular Cell. Researchers found that intrinsically disordered proteins (IDPs) kicked into gear, filling up the tardigrades' cells with an "amorphous matrix" that prevents them from going completely dry and dying.

根據(jù)發(fā)表在《分子細(xì)胞》雜志上的研究，研究人員將緩步動(dòng)物曬干，看看哪些基因會(huì)對(duì)壓力做出反應(yīng)。研究人員發(fā)現(xiàn)，內(nèi)在無(wú)序的蛋白質(zhì)(IDPs)發(fā)揮了作用，用一種“無(wú)定形基質(zhì)”填充緩步動(dòng)物的細(xì)胞，防止它們完全干燥和死亡。

They can shrug off extreme temperatures, but ...

它們可以不在乎極端的溫度，但是……

Mount Vinson is Antarctica's highest peak — and a likely home for tardigrades, which can live just about anywhere. (Photo: Wayne Morris/Shutterstock)

As mentioned earlier, these microscopic creatures that live on lichen and moss don't skip a beat when faced with cold temperatures. According to Smithsonian, they can survive extreme temperatures, frozen at minus 328 degrees Fahrenheit (minus 200 degrees Celsius) or heated to more than 300 degrees Fahrenheit (roughly 149 C). As with the other catastrophic conditions already mentioned, the secret is that under unfavorable conditions, they go into a state of suspended animation called the "tun" state. As a result, they can live almost anywhere, from Antarctica to the rainforest.

如前所述，這些以地衣和苔蘚為食的微生物在面對(duì)低溫時(shí)不會(huì)停止跳動(dòng)。根據(jù)史密森學(xué)會(huì)的說(shuō)法,它們可以生存的極端溫度,在- 328華氏度(- 200攝氏度)或加熱到超過(guò)300華氏度(約149攝氏度),正如前面提到的其他災(zāi)難性條件一樣，秘密在于，在不利的條件下，它們進(jìn)入一種被稱為“TUN”狀態(tài)的暫停動(dòng)畫狀態(tài)。因此，它們幾乎可以生活在任何地方，從南極洲到熱帶雨林。

They can resist radiation

它們能抵抗輻射

Humans are getting a lot more medical imaging tests these days, and perhaps tardigrades can teach us how to do it in the safest manner possible. (Photo: eAlisa/Shutterstock)

It was a team of Japanese researchers who figured out the secret behind the hardy critter's amazing defense against radiation. (Other researchers learned that one group of water bears could survive radiation doses of 5,000 to 6,000 grays, or absorbed energy per unit mass of tissue. In contrast, humans would barely survive a dose of 5 grays!) Among the animal's many coping strategies is a protein that protects its DNA from radiation damage. The researchers named it "Dsup" (short for "damage suppressor"). When the scientists transplanted the Dsup protein into human cells in the lab, it protected those cells, too.

是一組日本研究人員發(fā)現(xiàn)了這種頑強(qiáng)的生物驚人的防輻射能力背后的秘密。(其他研究人員了解到，一組水熊可以承受5000到6000灰的輻射劑量，或單位質(zhì)量組織吸收的能量。相比之下，人類僅能在5個(gè)灰人的劑量下存活。這種動(dòng)物的許多應(yīng)對(duì)策略之一是一種保護(hù)DNA不受輻射傷害的蛋白質(zhì)。研究人員將其命名為“Dsup”(損害抑制劑的縮寫)。當(dāng)科學(xué)家們?cè)趯?shí)驗(yàn)室中將Dsup蛋白移植到人類細(xì)胞中時(shí)，它也保護(hù)了這些細(xì)胞。