墨尔本PTE素材库——Shark Fins Contain Toxic “One–Two Punch”

墨尔本PTE素材库——Shark Fins Contain Toxic “One–Two Punch”

中文批注

鲨鱼肉和鱼翅，到底能不能吃？最近科学家们通过一系列实验，发现，鲨鱼肉中，不单单有一种叫做BMAA的毒素，更有有剧毒的甲基汞，对人体的大脑有害。

这段音频难度一般，但相对来说，生物类的专业词汇比较多。同学们可以趁此机会多做积累。澳大利亚语言学院会定期整理跟新墨尔本PTE素材库，让大家在复习，做题之余，有较多的听力和口语素材能够联系，同时，熟悉学习不同的话题，以及topic-related words。帮助大家提升语言能力、

听完这段音频，大家能不能回答出下面的这些问题呢？

• 鲨鱼肉里含的毒素会带来怎样的疾病？
• 研究者采用了多少种类的鲨鱼，分别来自哪里？
• 这个发现对谁有好处？

不能答上来的同学，快来看看transcript吧~

【Key vocabulary】

Toxic n. 毒素

Methyl mercury 甲基汞

Synergistic adj. 协同的

Living at the top of the food chain 生活在食物链的顶端

Neurodegenerative 神经性的

One-two punch 组合拳

Widespread 普遍的。

Mercury 汞

Cartilage 软骨

Full Transcript

Sharks can accumulate both methylmercury and a toxin called BMAA, which can have synergistic effects on human consumers. Christopher Intagliata reports.

Living at the top of the food chain, sharks can accumulate dangerous levels of methylmercury. So much that pregnant women and children are advised not to eat shark at all. But sharks can accumulate another toxin too, called BMAA, which has been linked to the development of neurodegenerative disease. Which could be bad news for shark eaters.

“Mercury in combination with BMAA is a one-two punch.” Deborah Mash, a professor of neurology at the University of Miami’s Miller School of Medicine. “These are two synergistic toxins. So even if there are low levels of exposure from the mercury or the BMAA, when humans are exposed to both of these toxins, then they will have a synergistic effect on the nervous system.”

BMAA starts out in cyanobacteria, and travels up the food chain through crabs and shrimp and fish. And, as previous studies have shown, all the way to sharks. What Mash and her colleagues wanted to know was how widespread the problem was, and if the chemical often appeared alongside mercury. So they analyzed fin and muscle samples from 10 species of shark—55 individuals in all—from the Atlantic and Pacific Oceans. And they found BMAA and mercury in all 10 species. Suggesting that exposure to that “one-two punch” could be pretty common. The results are in the journal Toxins. [Neil Hammerschlag et al.,Cyanobacterial Neurotoxin BMAA and Mercury in Sharks]

It’s still not clear at this point what sort of risk this occasional exposure through food might have. Still, Mash isn’t waiting.

“I myself would not want to be exposed to BMAA or methyl mercury in my diet by eating shark fin or shark meat or taking shark cartilage products. We already know that mercury is toxic to our health. And we already know that BMAA plus mercury is a very bad mix for the brain. So people need to be concerned, and I think that’s not only for the benefit of us as consumers, but also to the poor sharks, who are threatened with extinction.”

Conservationists have argued for years that sharks should be spared. Maybe now that it’s us who are threatened… people might finally start to leave them alone.

—Christopher Intagliata

(Source: http://www.scientificamerican.com/podcast/episode/shark-fins-contain-toxic-one-two-punch/)