科学美国人60秒 SSS DNA Samples Find a Lot of Fish in the Sea
时间：2018-12-24 作者：英语课 分类：2016年Scientific American(十一)月
The way we sample much of the world's oceans, to see what's living down there, is pretty basic: Ask fishermen. Or just stick a net down there, and examine what we catch. Neither method is ideal. "Because you basically catch the fish and kill them." Philip Francis Thomsen, a biologist at the Natural History Museum of Denmark. Another drawback, he says, is you can't do it everywhere. "If the bottom is too soft, or too rocky, or there's a coral reef, you don't want to use this invasive method above sensitive habitat."
So Thomsen and his team investigated an alternative, that's been used in freshwater with some success: they sampled the diversity and abundance of marine 1 life using something called environmental DNA 2, or "eDNA." Basically, genetic 3 material that fish leave behind. "So that is all sorts of bodily fluids that are expelled by the fish during its lifetime." And beyond its lifetime too—like when one fish gets eaten, and its remains 4 get expelled in the fecal matter of another. Bingo: eDNA.
Thomsen and his colleagues sampled seawater at various depths off the southwest coast of Greenland. And then fished out the eDNA in those samples. The researchers were able to identify 26 of the 28 fish families caught in the same area in trawling nets—and at similar abundances, too. They also found a few unique families missed by the nets, and lots of DNA from a species that, in net samples, seemed rare: the Greenland shark.
"We found the shark in almost all of the samples. That is because the shark just avoids the trawl. So here's an example of a species that is actually better surveyed by the environmental DNA than the trawling." The study is in the journal PLoS ONE. [Philip Francis Thomsen et al., Environmental DNA from Seawater Samples Correlate with Trawl Catches of Subarctic, Deepwater Fishes]
The technique's not quite ready for primetime in the marine setting: for one, ocean currents could transport a species' DNA far from where the fish may actually be found, and give inaccurate 5 measures. But in the future, it might take the fishing out of fish surveys.
—Christopher Intagliata
- Marine creatures are those which live in the sea. 海洋生物是生存在海里的生物。
- When the war broke out,he volunteered for the Marine Corps.战争爆发时，他自愿参加了海军陆战队。
- DNA is stored in the nucleus of a cell.脱氧核糖核酸储存于细胞的细胞核里。
- Gene mutations are alterations in the DNA code.基因突变是指DNA密码的改变。
- It's very difficult to treat genetic diseases.遗传性疾病治疗起来很困难。
- Each daughter cell can receive a full complement of the genetic information.每个子细胞可以收到遗传信息的一个完全补偿物。
- He ate the remains of food hungrily.他狼吞虎咽地吃剩余的食物。
- The remains of the meal were fed to the dog.残羹剩饭喂狗了。
- The book is both inaccurate and exaggerated.这本书不但不准确，而且夸大其词。
- She never knows the right time because her watch is inaccurate.她从来不知道准确的时间因为她的表不准。
