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  • 克隆 - 高级

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    Are cows cloned?
    ::奶牛克隆了吗?

    They are, but so are many other like sheep and goats. Cloning allows large animals to produce drugs or that are useful in medicine.
    ::克隆可以让大型动物生产毒品,或者对医药有用。

    Applications of DNA Technology: Animal Cloning
    ::DNA应用技术:动物克隆

    technology has proved very beneficial to humans. Transgenic animals are animals that have incorporated a gene from another into their genome . They are used as experimental models to perform phenotypic tests with genes whose function is unknown, or to generate animals that are susceptible to certain compounds or stresses for testing purposes. Other applications include the production of human , such as insulin . Many times these animals are rodents , such as mice, or fruit flies ( Drosophila melanogaster ). Fruit flies are extremely useful as genetic models to study the effects of genetic changes on . GloFish are the first genetically modified animal to be sold as a pet and are transgenic zebrafish transfected with a natural fluorescence gene. 
    ::转基因动物是将他人基因纳入基因组的动物,它们被用作实验模型,对功能未知的基因进行口腔试验,或产生易受某些化合物或压力影响的动物,以进行试验;其他应用包括生产人类,如胰岛素;这些动物在许多情况下是老鼠或水果蝇等鼠类动物(Drosophila melanogaster);水果苍蝇作为研究遗传变化对基因基因组的影响的遗传模型非常有用。GlolFish是第一个作为宠物出售的转基因动物,是带有天然荧光基因基因的转基因斑马鱼。

    But transgenic animals just have one novel gene. What about an animal with a whole new genome? Could a clone , a genetically exact copy of an organism , be developed using techniques associated with ? It could be argued that human cloning is one of the inevitable outcomes of modern biotechnology. It "simply" involves the removal of the from a somatic and its placement into an unfertilized egg cell whose nucleus has either been deactivated or removed. This new cell would mimic the zygote , the first diploid cell of a new organism. This new zygote is allowed to become established, and a few days later is placed into the uterus of a surrogate mother. Theoretically this would result in an individual genetically identical to the donor. Obviously, there are many ethical and legal issues associated with human cloning, and of course, it is not a "simple" procedure. But animal cloning is arguably a different story.
    ::但是,转基因动物只有一个新基因。关于一个拥有全新基因组的动物呢?一个克隆人,一个有机体的基因精确复制件,能否用相关技术来开发?可以认为人的克隆是现代生物技术不可避免的结果之一。“简单”是指将人体克隆从体外移走,并将其置于一个未受精的卵细胞中,其核不是被禁用,就是被切除。这个新细胞将模仿zygote,即新生物体的第一个浸泡细胞。这个新的zygote被允许建立起来,几天后被放置在代孕母亲的子宫里。理论上,这将导致个人与捐赠者在基因上完全相同。很明显,许多伦理和法律上的问题都与人类克隆有关,当然,它不是“简单”程序。但是动物克隆可以说是一个不同的故事。

    Dolly
    ::多圆

    In February 1997, Ian Wilmut and his colleagues at the Roslin Institute announced the successful cloning of a sheep named Dolly from the mammary glands of an adult female ( Figure  ) ( Nature 385 , 810-13, 1997). Dolly was the first mammal to be cloned from an adult somatic cell. The cloning of Dolly made it apparent to many that the techniques used to produce her could someday be used to clone human beings. This resulted in tremendous controversy because of its ethical implications. After cloning was successfully demonstrated by Dolly's creators, many other large mammals, including horses and bulls, were cloned. Dolly, however, was put down by lethal injection in February 2003. Prior to her death, Dolly had been suffering from lung and crippling arthritis. Although most sheep like Dolly live to be 11 to 12 years of age, postmortem examination of Dolly seemed to indicate that, other than her cancer and arthritis, she appeared to be quite normal. Dolly was a mother to six lambs, bred through normal methods.
    ::1997年2月,Ian Wilmut及其在Roslin研究所的同事宣布成功克隆了一名成年女性哺乳腺中名叫Dolly的羊(Figure)的Dolly(Natal385、810-13,1997年),Dolly是第一个从成人体细胞中克隆的哺乳动物,Dolly的克隆使许多人明显地看到,生产Dolly所用的方法有一天可以用来克隆人类,这引起了巨大的争议,因为它具有伦理意义。在Dolly的创造者成功展示了克隆之后,许多其他大型哺乳动物,包括马和公牛,都被克隆了。但是,Dolly在2003年2月通过注射致死,Dolly在死亡之前,一直患有肺部和严重的关节炎。尽管Dolly等大多数绵羊活到11至12岁,但Dolly的死后检查似乎表明,除了她的癌症和关节炎外,她似乎很正常。Dolly是六只羊的母亲,他们都是正常的。

    Cloning is now considered a promising tool for preserving endangered species.
    ::克隆现在被认为是保护濒危物种的一个很有希望的工具。

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    Dolly the sheep. Dolly was the first large mammal to be cloned.

    In animal cloning, the nucleus from a somatic cell is inserted into an egg cell in which the nucleus has been removed. This process called somatic cell nuclear transfer results in essentially a fertilized egg, a zygote produced in an artificial manner. The resulting cell is cultivated and after a few divisions, the developing ball of cells is placed into a surrogate mother's uterus where it is allowed to develop into a fetus . The developing fetus will be genetically identical to the donor of the original nucleus ( Figure  ).
    ::在动物克隆中,体细胞的核被插入一个切除核的卵细胞中。这个称为体细胞核转移的过程基本上导致一个受精卵,一种以人工方式生产的zygote。由此形成的细胞在培养,经过几个分解后,细胞的发育球被放置在代孕母子宫中,允许它发展成胎儿。发育中的胎儿在基因上与原核的捐献者相同(图 )。

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    Reproductive cloning: The nucleus is removed from a somatic cell and fused with a denucleated egg cell. The resulting cell may develop into a colony of cloned cells, which is placed into a surrogate mother. In therapeutic cloning, the resulting cells are grown in tissue culture; an animal is not produced, but genetically identical cells are produced.

    Risks of Cloning
    ::克隆风险

    Producing a cloned animal is not an insignificant achievement. Most likely it has taken a significant effort by the group of scientists attempting to make the clone. Rarely do scientists publish or discuss the many cloning that failed, or even in the successful clones, the issues that tend to arise later, during the animal's development to . Cloning animals shows us what might happen if we try to clone humans.
    ::生产克隆动物并非一个微不足道的成就。 科学家们试图制造克隆人,这极有可能花费了巨大的努力。 科学家们很少公布或讨论许多失败的克隆,甚至在成功的克隆人中也很少发表或讨论后来在动物发育过程中、在动物发育过程中会出现的问题。 克隆动物向我们展示了如果我们试图克隆人类时会发生什么。

    High Failure Rate
    ::高失及率率

    Producing a clone through somatic cell nuclear transfer is not every efficient. The success rate ranges from 0.1 percent to 3 percent, which means that for every 1000 tries, only one to 30 clones are made. In other words, there are 970 to 999 failures in every 1000 attempts. That's a tremendous failure rate. This failure rate may be due to a number of circumstances. Keep in mind that somatic cell nuclear transfer is an artificial process. It is not a natural process, and there may still be components of the and development process that are not well understood.
    ::通过体细胞核转移产生克隆并非效率最高。成功率介于0.1%至3%之间,这意味着每1000次试验中只有1至30次克隆。换句话说,每1000次试验中就有970至999次失败。这是一个巨大的失败率。这个失败率可能是由于一些情况造成的。记住体细胞核转移是一个人工过程。这不是一个自然过程,而且可能还有不为人们所理解的开发过程的组成部分。

    1. The enucleated egg and the transferred nucleus may not be compatible.
      ::切开的卵和转移的核可能不兼容。
    2. An egg with a newly transferred nucleus may not begin to divide or develop properly.
      ::带有新转移核心的卵可能无法开始适当分割或发展。
    3. Implantation of the embryo into the surrogate mother might fail.
      ::把胚胎植入代孕母亲身上 可能会失败
    4. The itself might fail.
      ::本身可能失败。
    Large Offspring Syndrome
    ::大型离子体综合症

    Cloned animals that do survive tend to be much bigger at birth than their natural conceived animals of the same species. This is known as "Large Offspring Syndrome". Cloned animals with this syndrome have abnormally large organs , which can lead to , flow and other associated problems. However this syndrome is unpredictable; it does not always occur, so scientists cannot predict which clones will be affected.
    ::活下来的克隆动物在出生时往往比它们生来自然想象的同一物种的动物要大得多。这被称为“大外星综合症 ” 。 与这种综合症结合的被克隆动物有异常大的器官,可能导致、流动和其他相关问题。 然而,这种综合症是不可预测的;它并非总能发生,因此科学家无法预测哪些克隆人会受到影响。

    Abnormal Gene Expression
    ::异常基因表达式

    Though surviving clones have identical genomes to their "parent," are they truly clones? Will they express the necessary genes at the proper times? is an extremely complicated and highly regulated cellular process (see the Regulation of Gene Expression (Advanced) concepts). One significant issue is to reprogram the transferred nucleus so that it thinks it is in the zygote, mimicking the natural processes that must be initiated at fertilization, including the expression of the appropriate genes. The cell must be programmed so that the genes that must be expressed in that zygote are truly expressed. The nucleus cannot think it is in a differentiated cell, such as the somatic cell it came from.
    ::尽管幸存的克隆人拥有与其“亲生”相同的基因组,它们是否真的克隆?它们是否在适当的时候表达必要的基因?它们是否表示出必要的基因?它们是一个极其复杂和高度规范的细胞过程?是一个极其复杂和高度规范的细胞过程(见基因表达(高级)概念 ) 。 一个重要问题是重新编程转移的核,使其认为它是在zygote中,模仿在受精时必须启动的自然过程,包括适当基因的表达方式。细胞必须编程,以便以zygote中必须表达的基因能够真正表达出来。核心不能认为它是在不同的细胞中,比如它来自的体细胞。

    Telomeric Differences
    ::电荷差异

    As cells divide, their get shorter. This is because the telomeres, the DNA sequences at both ends of a chromosome, lose material every time the DNA is replicated. The older the animal is, the shorter its telomeres will be, because of the number of cell cycles the cells have been through This is a natural part of aging. So, what happens to the clone if its transferred nucleus is already fairly old? Will the shortened telomeres affect its development or lifespan? The answer is still unclear. But starting a new organisms with "old" DNA with shortened telomeres is bound to have some effects, at least in some clones. Some cloned animals may be affected, others may not. Dolly the sheep's chromosomes did have shorter telomere lengths than normal. This means that Dolly's cells were aging faster than the cells from a normal sheep.
    ::随着细胞的分裂,它们的细胞会变短。 这是因为调聚物, 染色体两端的DNA序列, 每次复制DNA时都会丢失材料。 动物越老, 其调聚物就越短, 因为细胞已经经历的细胞循环次数越少。 这是衰老的自然部分。 所以, 如果转基因核已经相当老了, 克隆人会发生什么? 缩短的调聚物会影响它的发育或寿命吗? 答案仍然不清楚 。 但是, 使用“ 老的” DNA开始新的生物, 并且缩短了调聚物的基因, 必然会产生一些效果, 至少在一些克隆人中。 一些克隆动物可能受到影响, 另一些则可能没有。 多莉的羊染色体的长比正常的羊的细胞长得要短。 这意味着多利的细胞比正常的羊细胞的生长速度要快。

    Summary
    ::摘要

    • Transgenic animals are animals that have incorporated a gene from another species into their genome. They are used as experimental models to perform phenotypic tests with genes whose function is unknown, or to generate animals that are susceptible to certain compounds or stresses for testing purposes. Other applications include the production of human hormones, such as insulin.
      ::转基因动物是指将另一物种的基因纳入基因组的动物,它们被用作实验模型,对功能未知的基因进行小类试验,或产生易受某些化合物影响或压力影响的动物,用于试验目的,其他应用包括生产人类激素,例如胰岛素。
    • Animal cloning is the generation of genetically identical animals using DNA from a donor animal, not a gamete. Dolly, a sheep, was the first mammal to be cloned from an adult somatic cell.
      ::动物克隆是利用捐赠动物的DNA而不是植物来生成基因相同的动物。 Dolly,一只绵羊,是第一个从成人体细胞中克隆哺乳动物。

    Review
    ::回顾

    1. What is the difference between a transgenic animal and a cloned animal?
      ::转基因动物和克隆动物有什么区别?
    2. Who was Dolly? Why was she important?
      ::多莉是谁 为什么她重要
    3. What are the risks of cloning?
      ::克隆的风险是什么?