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- You will hear a recorded passage. After that you will hear five questions. Both the passage and the questions will be read twice. When you hear a question, you should complete the answer to it with a word or a short phrase (in no more than three words).The questions and incomplete answers are printed in the textbook for your reference.
- 1.Who is Spark?
Spark is a .
2. What has happened to Spark?
He has just .
3. If you want to have Spark back, what can probably help you?
A called cloning can probably help.
4. For many years, what have scientists been cloning?
Scientists have been cloning all kinds of for years.
5. What are some of the common problems for cloned animals?
Cloned animals tend to have serious and shorter life.
- 正确答案:1. dog 2. died 3. scientific process 4. animals 5. health problems
- Script:
He had been part of your family for as long as you can remember. He understood you better than anyone else. And now, sadly, your beloved dog Spark has died.
Your mom has offered to buy you a new dog, a dog just like Spark. But you don’t want a new dog. You want Spark. What to do?
Thanks to a scientific process called cloning, you can probably have Spark back again if you really want.
Scientists have been cloning all kinds of animals for years. Now some companies offer pet-cloning services. They say cloning is a way to honor a beloved animal.
But you should realize that cloning has a dark side. For every successful clone, there are dozens of failures. Cloned animals tend to have serious health problems and shorter life.
脚本:
从你记事起,他就是你的家人了。他比任何人都更了解你。现在,很遗憾,你心爱的狗斯帕克死了。
你妈妈给你买了一只新狗,一只像Spark一样的狗。但是你不想要一只新狗。你想要的火花。要做什么吗?
多亏了一种被称为克隆的科学方法,如果你真的想要的话,你可能还能重燃希望之火。
科学家们多年来一直在克隆各种动物。现在一些公司提供宠物克隆服务。他们说克隆是一种尊重心爱动物的方式。
但你应该意识到克隆有黑暗的一面。每一个成功的克隆,都有几十个失败。克隆动物往往有严重的健康问题和更短的寿命。
- Unit 05 : Genetic Technology > Text Study > Text A
- Dolly Scientist Plans to Clone the Scottish Wildcat
1 Dr. Bill Ritchie, a member of the team that cloned Dolly the sheep more than fifteen years ago, is turning his attention to helping save one of Scotland’s most endangered species, the Scottish Wildcat, which is also known as the “Scottish Tiger.”
2 Dr. Ritchie is working on a new cloning technique. It is hoped that this technique will become a template for other plans aimed at cloning endangered animals.
3 The Scottish Wildcat is now seriously endangered because of the loss of habitat and hybridization with the domestic cat. These problems have resulted in an estimate of only 400 animals remaining in existence.
4 The project has some funding from Genecom Ltd., but Dr. Ritchie is looking for further financial backing to help stop the animal becoming extinct.
5 Hybridization, or crossing with domestic animals, may save the wildcat, as its ability to hybridize also allows the possibility of using domestic cat eggs for cloning. “This crossing indicates that there is a good chance of cloning being successful cross species, as only animals which are very close genetically have been successfully cloned,”says Dr. Ritchie.
6 “Several cat species have been cloned using the domestic cat. It is very difficult to find pure wildcats because of their crossing with domestic animals, but modern scientific techniques are able to select animals which are purebred. Cells collected from these animals by taking a small piece of skin would be grown to supply cells for the cloning process.” Dr. Ritchie says. Eggs from domestic cats, which would be available from tissue recovered during spaying of the animal, could be used as the starting material for the cloning process.
7 A project from the Royal Zoological Society, which is being carried out in the Cairngorms to prevent hybridization with the domestic cat, could also be helpful. “Domestic cats are being spayed free of charge in the Cairngorms to try to protect the wildcats, but this may be a convenient source of eggs.”
8 Dr. Ritchie adds: “We spend lots of time traveling to Asia to see endangered species there, but seldom think of the loss of our own wildcat, which is even more endangered than many of the animals we travel half way round the world to see. The Scottish Wildcat is probably more difficult to see than many other big cats. It must be preserved if we are to have a healthy ecosystem.”
9 The technique used for cloning the animal would be similar to that used to clone Dolly, but it has moved on by using eggs which can be recovered from material discarded during spaying. The immature eggs recovered from the tissue would mature in the right environment. This development from an immature state to an egg suitable for cloning would be carried out in an artificial environment. After about twenty-four hours, the egg would be suitable for trying to produce an embryo which would be transferred to a female cat.
10 Many animals in zoos fail to breed because the social and nutritional condition of the animal is not met and because the animals do not get the exercise needed to keep them in breeding condition. “Animals which do not breed in the early years will often not breed in later life, but these animals would be able to supply cells for the cloning process,” says Dr. Ritchie. “Dolly was a great achievement leading to many breakthroughs, and this is just another use for the technology which was proved just a few years ago.”
- 多莉羊研究者计划克隆苏格兰野猫
- 1 比尔•里奇博士是15年前克隆多莉羊的研究团队中的一员,现在他将自己的注意力转向了保护苏格兰野猫。苏格兰野猫也称苏格兰虎,是苏格兰最稀少的濒危动物之一。
- 2 里奇博士正在钻研一种新的克隆技术,这种技术有望成为其他濒危动物克隆计划的模板。
- 3 因为栖息地丧失及与家猫杂交等原因,苏格兰野猫现在处在十分危险的境地,目前只剩下大约400只。
- 4 该计划得到了基因公司的部分资助,但里奇博士还在寻求更多的资助,以防这个物种灭绝。
- 5 野猫能够与家猫杂交,这种能力也许能够拯救野猫,因为这意味着家猫的卵子可以用来克隆野猫。“跨物种杂交能力表明,跨物种克隆成功的可能性很高,因为只有基因非常接近的物种才有过成功克隆的例子。”里奇博士说道。
- 6 “不少猫科动物都曾借助家猫成功地克隆过。现在很难找到纯种的野猫了,因为野猫基本上都和家猫杂交过,不过现代技术能够挑出纯种野猫。从纯种动物身上取一小块皮肤,就可以培养出可供克隆的细胞。”里奇博士解释道。家猫的卵细胞可以从阉割后回收的组织中获取,有了这些卵细胞,克隆过程就可以开始了。
- 7 皇家动物学会正在凯恩戈姆山推行一个项目,预防野猫和家猫杂交,这项工作同样也有助于保护野猫。“该项目在凯恩戈姆地区免费阉割家猫,目的是为了保护野猫,这样也便于获得家猫卵细胞。”
- 8 里奇博士称:“我们花很多时间,跑到亚洲去,观察那儿的濒危动物,却没想到我们的野猫也在消失,而且我们的野猫甚至比那些我们在另外一个半球看到的许多动物还要稀少。苏格兰野猫也许比大多数大型猫科动物更难见到。如果我们想拥有一个健康的生态系统,我们就必须保护野猫。”
- 9 克隆野猫的技术与克隆多莉羊的技术十分相似,但现在技术发展了,可以利用从阉割下来的物质中提取出的卵细胞。从动物组织中提取出的未成熟卵细胞可以在适当环境下培育成熟。未成熟的细胞可以在人工环境下培养成适合克隆的卵子。经过24小时的培养,卵子便可以用于制作植入母猫体内的胚胎了。
- 10 动物园里很多动物无法繁衍,因为生活状况和营养状况达不到要求,同时又缺乏锻炼,因此不具备生殖条件。“如果动物早年不能繁衍,之后也基本不可能再生殖后代。不过,这些动物能够为克隆提供必要的细胞。”里奇博士说。“克隆多莉羊是个了不起的成就,引发了很多重大突破。几年前,克隆技术被证明行之有效,现在这个项目是该技术的又一次应用。”
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