这是个吸引眼球的标题，其实只是转贴一篇新闻。恰好今天从City Hall赴所谓的国王宴回来，这个国王宴请诺贝尔奖获得者的地方。心里有很多感触，没时间写，每日里疲于应付作业和阅读。怎一个郁闷了得！
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“沉默”是金——诺贝尔生理学或医学奖成果解读
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| 2006年10月03日 00:14:09 来源：新华网 |
新华网北京１０月２日电（记者林小春）１９９０年，曾有科学家给矮牵牛花插入一种催生红色素的基因，希望能够让花朵更鲜艳。但意想不到的事发生了：矮牵牛花完全褪色，花瓣变成了白色！科学界对此感到极度困惑。
类似的谜团，直到美国科学家安德鲁·法尔和克雷格·梅洛发现ＲＮＡ（核糖核酸）干扰机制才得到科学的解释。两位科学家也正是因为１９９８年做出的这一发现而荣获今年的诺贝尔生理学或医学奖。
根据法尔和梅洛的发现，科学家在矮牵牛花实验中所观察到的奇怪现象，其实是因为生物体内某种特定基因“沉默”了。导致基因“沉默”的机制就是ＲＮＡ干扰机制。
此前，ＲＮＡ分子只是被当作从ＤＮＡ（脱氧核糖核酸）到蛋白质的“中间人”、将遗传信息从“蓝图”传到“工人”手中的“信使”。但法尔和梅洛的研究让人们认识到，ＲＮＡ作用不可小视，它可以使特定基因开启、关闭、更活跃或更不活跃，从而影响生物的体型和发育等。
诺贝尔奖评审委员会在评价法尔和梅洛的研究成果时说：“他们的发现能解释许多令人困惑、相互矛盾的实验观察结果，并揭示了控制遗传信息流动的自然机制。这开启了一个新的研究领域。”
科学家认为，ＲＮＡ干扰技术不仅是研究基因功能的一种强大工具，不久的未来，这种技术也许能用来直接从源头上让致病基因“沉默”，以治疗癌症甚至艾滋病，在农业上也将大有可为。从这个角度来说，“沉默”真的是金。美国哈佛医学院研究人员已用动物实验表明，利用ＲＮＡ干扰技术可治愈实验鼠的肝炎。
目前，尽管尚有一些难题阻碍着ＲＮＡ干扰技术的发展，但科学界普遍对这一新兴的生物工程技术寄予厚望。这也是诺贝尔奖评审委员会为什么不坚持研究成果要经过数十年实践验证的“惯例”，而破格为法尔和梅洛颁奖的原因之一。
诺贝尔生理学或医学奖评审委员会主席戈兰·汉松说：“我们为一种基本机制的发现颁奖。这种机制已被全世界的科学家证明是正确的，是给它发个诺贝尔奖的时候了。”
高中生物学的特好，就喜欢看到DNA RNA 的题目。
从NYtime上抄来的：
Prior to their discovery, plant biologists over many decades had found odd exceptions to Mendel’s laws of heredity, including some unexplained effects produced by injecting RNA, the less-well-known cousin of DNA, into plants. Both are chemicals called nucleic acids, but DNA is longer and more stable and is used by the cell for the archival function of storing genetic information. RNA is shorter and more active, and performs many of the cell’s more difficult tasks, like making copies of the genes in DNA and directing the synthesis of the proteins specified by the genes.
The plant biologists supposed that injecting new RNA might somehow interfere with the protein-synthesizing process but did not understand how to make this happen reliably. Drs. Fire and Mello made a decisive advance by showing in roundworms that the injected RNA had to be double-stranded and that the sequence of chemical units had to be the same as or very similar to those of the gene being singled out. Under these conditions, any gene in the roundworm could be switched off by injecting double-stranded RNA with a sequence of units that corresponded to those in part of the gene’s DNA.
Other scientists soon figured out the evolutionary reason for this curious mechanism. It is a defense against viruses, many of which have double-stranded RNA as their genetic material. When a virus enters a cell, its RNA is chopped up and the fragments are used to battle the virus itself. The cell takes one strand of each fragment and tests all the messenger-RNA’s — those that direct synthesis of proteins — to see if they match it. Only the virus’s RNA’s will match, and they are destroyed before they can start making the virus’s proteins.
The perceived importance of the Fire-Mello finding increased even more when other researchers discovered that it had a second dimension. It seemed that cells, having evolved this handy mechanism for suppressing a virus’s genes, then adapted it to controlling their own genes.
Both plants and animals, probably independently, evolved genes that do not make proteins but simply generate an RNA molecule that loops back on itself to form a hairpin twist similar to a virus’s double-stranded RNA. These RNA’s, known as micro-RNA’s, use the same gene-silencing mechanism as is set off by viruses, and ratchet down the activity of many of the cell’s own genes.
The genes that make micro-RNA’s are a novel class, quite different from the conventional genes that direct the synthesis of proteins. Researchers are now busily exploring how many exist in the human and other genomes. Micro-RNA genes seem to be important in processes like embryonic development and in cancer. Gene silencing and micro-RNA’s have become overnight a major field of biological research, and one that may well attract other Nobel Prizes in the future.
cityhall都没看见你。。
中秋快乐