(单词翻译:单击)
听力文本
From VOA Learning English, this is the Environment and Science Report.
Many science fiction stories tell about explorers arriving in a new world. The explorers then use some kind of high-tech device to test for breathable air or signs of life. But here on Earth, science fiction is becoming reality through a new sampling technology called environmental DNA, or eDNA for short. Scientists can use it to identify rare or invasive species, study biodiversity or estimate fish populations with just a little air or water.
Ryan Kelly is an ecologist at the School of Marine and Environmental Affairs at the University of Washington in Seattle. He works in a laboratory there with other researchers. They study the genetic material released by living creatures.
"Essentially we can take a sample of soil or air -- and in our case -- water, and we can sequence the DNA out of it and tell you what is there."
Ryan Kelly says he and his research team are studying water samples collected from Puget Sound. He says the cost of gene sequencing has "plummeted in recent years." That makes DNA testing more widely available.
Environmental DNA can be used in two ways. One is to identify the creatures that live in a certain place. The other is to confirm the presence or lack of a specific creature.
Caren Goldberg heads the new eDNA lab at Washington State University in Pullman, Washington. She is one of the first biologists in the northwestern United States to take the technology from the testing phase to actually using it.
"It is extremely useful for species that are really hard to find. I have spent many hours looking for species that I was pretty sure were there -- looking under rocks, looking in water, doing all kinds of surveys."
Caren Goldberg sees eDNA as a way to get answers more efficiently, safely and with less destruction compared to traditional survey techniques. Until recently, scientists depended on snorkeling, netting or using an electric current to temporarily capture fish.
"We're absolutely at this point where proof-of-concept has been established. I don't think everyone necessarily is on board yet, but I think the majority of the people are on board."
This newer way to identify what lives in the environment is becoming popular around the world. Animal experts in Vietnam are using the eDNA to find the last, wild Yangtze giant softshell turtles. One researcher on the Caribbean island of Trinidad is using the sampling technology to find endangered golden treefrogs. And in Madagascar, it is being used to identify amphibian diseases.
Ms. Goldberg has used eDNA testing to confirm the local extinction, disappearance, of a leopard frog in the American state of Idaho. She has also been asked to document the spread of the New Zealand mudsnail in the state of Washington. The creature has been found in lakes and other waterways across the state.
Now, the U.S. Bureau of Land Management wants Caren Goldberg to look for the Columbia spotted frog in two other western states. The rare amphibian is a candidate for the federal government's threatened species list.
Scientists working with the technology say they do not expect robots to replace field biologists anytime soon. But the old-fashioned field work could soon be more targeted.
A related research goal is to show how long environmental DNA can last and how far it can travel in different environments.
And that’s the Environment and Science Report from VOA Learning English. For more environment, science and agriculture reports, go to our website learningenglish.voanews.com. I’m Jonathan Evans.
词汇解释
1.sequence n. [数][计] 序列；顺序；续发事件 vt. 按顺序排好
The chronological sequence gives the book an element of structure.
时间顺序让这本书有了一定的结构。
2.amphibian n. [脊椎] 两栖动物；水陆两用飞机；具有双重性格的人 adj. 两栖类的；[车辆] 水陆两用的；具有双重性格的
Both the toad and frog are amphibian.
蟾蜍和青蛙都是两栖动物。
3.snorkeling n. 浮潜；潜水；浅滩潜水 v. 用水下通气管潜航；用通气管潜泳（snorkel的ing形式） adj. 潜浮的
Swim off the side of the ship and snorkel in some of the clearest waters imaginable.
游离小船边，用呼吸管潜游到可以想像得到的一些最清澈的水域。
4.leopard n. 豹；美洲豹
The young leopard separated from its mother would be eaten by other beast.
与母亲离散的幼豹很可能被其他的野兽吃掉。
内容解析
1.I don't think everyone necessarily is on board yet, but I think the majority of the people are on board.
on board 支持的; 赞同的；在船（火车、飞机）上
We were able to keep some moderate and conservative Democrats on board.
我们能够继续使一些温和保守的民主党议员支持我们。
The six astronauts on board will spend ten days in space.
飞船上的6名宇航员将在太空度过10天。
参考译文
这里是美国之音慢速英语环境和科学报道。
很多科幻小说都讲述探索者来到新世界，然后使用新型高科技设备来测试可呼吸气体或生命迹象。但在地球上，通过名为环境DNA(或eDNA)的新样本技术，科幻小说正在成为现实。科学家们能使用这种技术来识别罕见或侵入性物种，只需少量空气或水来研究生物多样性或估计鱼群大小。
雷恩·凯里是华盛顿大学西雅图分校海洋和环境事务学院的生态学家，他和其他研究员在一所实验室共事，他们研究生物释放出来的遗传物质。
“从根本上来说，我们能提取土壤或空气样本，这里我们用的是水，我们能排出其DNA序列，告诉你里面是什么生物。”
雷恩·凯里说他和他的研究团队在研究从普吉特湾采集的水样本，他说基因排序的成本“最近几年骤降”，这使得DNA测试的应用更加广泛。
环境DNA有两个方面的应用，一个是识别出生活在一定地方的生物，另一个是确认某种生物的存在与否。
卡伦·戈德堡是华盛顿普尔曼校区新设立的环境DNA实验室负责人，她是美国西北部第一批将该技术从试验阶段进入实际应用的生物学家之一。
“这对于极难找到的物种来说非常有用，我花了很长时间来寻找，以及做各种调查来寻找一些物种，我确认它们在那里存在。”
卡伦·戈德堡认为与传统调查技术相比，eDNA是更有效、安全和破坏性更小的寻找方法。直到最近，科学家都依靠浮潜、下网或使用电流来临时捕鱼。
“显然我们进入了建立概念验证的这个阶段。我认为不是所有人都已经进入这个阶段，但我认为绝大多数人已进入了这个阶段。”
这种寻找环境中生物的新方法在全世界都开始流行，越南动物专家使用eDNA来寻找最后的野生斑鳖。加勒比岛国特立尼达的一位研究者使用这种样本技术来寻找濒危金色树蛙。在马达加斯加，该技术被用来识别两栖动物疾病。
戈德堡使用eDNA测试来确认美国爱达荷州的豹蛙在当地是否已经灭绝，她还被要求记录新西兰田螺在华盛顿州的蔓延。这种生物已经在该州各地的湖泊和水域中被发现。
现在，美国土地管理局希望卡伦·戈德堡在两外两个西部州寻找哥伦比亚斑点蛙，这种罕见的两栖动物即将被列入联邦政府确认的濒危物种名单。
研究这种技术的科学家表示，他们并不期望自动仪器很快能取代实地考察的生物学家。但这种老式的野外工作很快可以更具针对性。
相关研究的一个目标是探明环境DNA可以持续多久，以及在不同环境中能传播多远。
这就是美国之音慢速英语环境和科学报道，登陆learningenglish.voanews.com获得更多环境、科学和农业报道，我是乔纳森·伊万斯。
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