一起聽英語 180 病毒

病毒存在了多少年，我們?nèi)梭w內(nèi)有多少基因?這些科學問題來讓我們揭曉。

William: Hello and welcome to 6 minute English. I hope you're ready for another five

minutes and fifty-five seconds of wonderful English language conversation

about an interesting topic from BBC News. I'm William Kremer.

Helen: Hello, I'm Helen Hu. Today we're talking about genes...

William: Oh right! Is that why we're both wearing jeans?

Helen: No, no, not that kind of jeans. Genes spelled G-E-N-E-S – these are the

molecules in our body which hold genetic information. So genes tell our

bodies how they should grow and develop.

William: Right, and genes are what parents hand down to their children. We carry

genes from one generation to the next.

Helen: Now before we go any further, it's time for our weekly quiz. Were you very

good at science at school, William?

William: Not particularly.

Helen: Good! You'll be rubbish at this then. OK, the question is: How many genes do

human beings have? Is it

a) between 10,000 and 25,000 or is it

b) between 100,000 and 250,000 or

c) between 1 million and 2.5 million

William: OK, well I have no idea so I'm going to go for c) between 1 million and 2.5

million.

Helen: OK, well the answer will be at the end of the programme. Now, a new

scientific study has looked at the genes of lots of animals and found traces of

the same viruses that existed a long time ago.

William: Right, they found traces – signs that something happened or existed. And the

traces they found were of viruses, the tiny creatures that spread infectious

diseases. So Helen, they think that these viruses have existed for millions of

years then...?

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Helen: Exactly. Let's listen to a clip from BBC correspondent David Shukman. See if

you can hear which animals the researchers studied:

BBC correspondent David Shukman:

Researchers from Oxford, New York and Belgium have investigated the genes of 38

mammals – including humans, mice, elephants and dolphins, and they've found that most of

them share traces of the same ancient viruses. The work has established that at least one

virus infected our common ancestors as long as one hundred million years ago.

Helen: So, did you hear which animals were mentioned?

William: The researchers investigated 38 different mammals including humans, mice,

elephants and dolphins.

Helen: That's right. And by comparing the genes of the animals they've concluded

that there was at least one virus that infected our ancestors perhaps a

hundred million years ago.

William: Wow. An ancestor is a person or plant that is related to something today but

that lived earlier. So... so what? So what, Helen? What's the significance of

that?

Helen: Well, for a start it suggests that these viruses are incredibly good at survival.

And as we will hear in our next clip, these diseases have not only survived,

but they also have evolved – they have changed and adapted slowly over a

long time.

William: OK, so let's hear the next clip now. See if you can hear the word that David

Shukman uses instead of the word viruses.

BBC correspondent David Shukman:

The scientists found that these micro-organisms have adapted to stay within their host cell,

where they have thrived. So within the double helix of our DNA lies not only a legacy of past

infections but also a miniature eco-system in which the viruses live on and evolve.

William: David Shukman used the word micro-organisms instead of the word viruses. A

micro-organism is a very very small creature.

Helen: He said the scientists found that the micro-organisms had thrived, meaning

they had prospered, they had developed well. The research suggests that our

genes actually help viruses to survive and evolve. And some viruses have

developed positive outcomes. For example the protein syncytin evolved from

a virus and has helped develop the female placenta.

William: OK, so these micro-organisms can be good things?

Helen: Well, they are not exactly 'good', but they have helped us to evolve.

William: Ah sorry, I wasn't being very 'scientific'! Let's hear the final clip now, and

we're going to hear the opinion of the senior researcher on the project. See if

you can hear why he thinks his research could be useful in the future.

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BBC correspondent David Shukman:

According to the senior author of the study, Dr Robert Belshaw of Oxford University,

understanding these survivors from the distant past may provide clues to the early detection

of cancers or infections.

William: Robert Belshaw thinks understanding the viruses might help the early

detection of cancers or infections – they might help us notice these diseases

early on.

Helen: OK, time to hear the answer to our quiz. I asked you how many genes human

beings have and you choose c) between 1 million and 2.5 million. Well, the

answer is a) 10,000 – 25,000.

William: Huh.

Helen: Ok, I can tell you're not that interested in this so why don't you do something

useful and remind us of today's vocabulary?

William: Okey-doke.

genes

a trace

a virus

an ancestor

to evolve

a micro-organism

to thrive

detection

Helen: If you would like to know more about these words, download our pdf script on

bbclearningenglish.com.

William: Goodbye!

Helen: Bye!