RNA是一种类似于DNA的分子,但是其分子量比DNA小得多。它的职能之一是充当信使将遗传信息从细胞核运送至制造蛋白质的机器核糖体。每一个信使RNA都是由双螺旋DNA的一个单链编码转录而成。双链RNA通常只存在于病毒体内。哺乳动物细胞只能正常识别单链RNA,如果发现双链RNA就会迅速将其销毁,以保护机体免受病毒感染。
This aversity to double-stranded RNA means short hairpins can be used to knock out themessengers, thus nullifying the signal from the underlying gene. It is just a question ofmaking a hairpin with an appropriate genetic sequenceone that is the same as the missingstrand of the original DNAso that the hairpin will combine eagerly with the messenger toform a double-stranded molecule. Modern gene-synthesis techniques mean this is not hardto do. Dr Bernards therefore did it with the messengers of 20,000 genes, to see which, if any,are implicated in the development of resistance to Xalkori.
机体对双链RNA的排斥性意味着可以利用短发卡RNA破坏信使RNA,从而阻断相应基因的信号传递。问题的关键是设计出合适的发卡结构,其遗传序列必须与其替代的DNA序列一致,才能迅速准确地结合其编码的RNA成为双链RNA分子。利用DNA合成技术很容易完成这项任务。因此,伯纳兹博士对2000个基因的信使RNA进行一一实验,以确认与产生Xalkori抗药性有关的基因是否存在其中、是具体的哪一个。
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