文字稿

《科學(xué)》雜志上發(fā)表的一項(xiàng)研究報(bào)告顯示，吸煙者一生中吸的煙與人體內(nèi)基因轉(zhuǎn)變的次數(shù)有著直接的聯(lián)系。這些基因轉(zhuǎn)變是永久性的，就算吸煙者成功戒煙，也無(wú)法重新將其修復(fù)。請(qǐng)聽(tīng) BBC 記者 Fergus Walsh 的報(bào)告。

The researchers sequenced the genome of thousands of cancers. They calculate that a 20 a day smoker will accumulate an average of 150 mutations every year in each lung cell - 97 in the larynx and 23 in the mouth. These changes are permanent, and each one represents a chance of triggering cancer. Even in tissues not directly exposed to smoke, there are DNA mutations - 18 per year in the bladder and six in the liver.

The joint lead author Prof Sir Mike Stratton, of the Wellcome Trust Sanger Institute, said DNA analysis would help explain the mechanisms triggering other cancers.

"By looking in the DNA of those cancers, we will find these mutational signatures, these archaeological traces of the past exposures, these will provide us clues to the agents that are responsible, and that will lead potentially to prevention."

One clear message from this research is that the quicker and younger smokers quit, the fewer DNA mutations they will be harbouring.

詞匯表

sequenced 按次序排列
genome 基因組，染色體組
accumulate 累積（數(shù)量逐漸增加）
mutations 突變、變異
larynx 喉
triggering 引發(fā)
mechanisms 原理、機(jī)制
archaeological 考古學(xué)的
harbouring 使藏著，使?jié)摲?

測(cè)驗(yàn)

請(qǐng)聽(tīng)報(bào)道并回答下列問(wèn)題。

1. How many mutations are seen on average in each lung cell every year for a 20 a day smoker?

2. Which part of the body is more likely to experience DNA mutation for a smoker?

3. True or false? ‘Tissues not directly exposed to smoke are protected from DNA mutations.’

4. Which word has a similar meaning to ‘historical’?

答案

1. How many mutations are seen on average in each lung cell every year for a 20 a day smoker?
On average 150 mutations can happen to each lung cell.

2. Which part of the body is more likely to experience DNA mutation for a smoker?
The larynx or the voice box is most likely to experience DNA mutations for a smoker.

3. True or false? Tissues not directly exposed to smoke are protected from DNA mutations.
False. Even tissues that are not directly exposed to smoke are at risk from DNA mutations.

4. Which word has a similar meaning to ‘historical’?
Archaeological.