2008-07-31
RNAi原理演示
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RNA干扰（RNA interference，RNAi）是真核生物体内由双链RNA（double-stranded RNA，dsRNA）介导的降解同源RNA的现象,是一种进化上保守的抵御转基因或外来病毒侵犯的防御机制.在细胞中，长的dsRNA被类似RNA酶Ⅲ的Dicer酶切割成21～26个核苷酸的干扰性小RNA（small interfering RNA，siRNA）。随后，siRNA与蛋白复合物结合后形成RNA诱导沉默复合物（RNA-induced silencing complex，RISC），并解链。而有活性的RISC在其中的siRNA反应链指导下同与其互补的转录物结合，导致RNA的降解。
自从2006年诺贝尔医学奖颁发给RNA干扰技术的发明者安德鲁·菲尔和克雷格·米洛之后， RNAi技术火的不得了，什么都要往上沾边，呵呵，我也曾今把这个原理应用到我的试验中。最近在网络上收集到两个不错的RNAI视频，整理到这里，大家发动脑筋，看能不能从中有所收获…
flash演示：
How does RNAi work? Genetic and biochemical data indicate a possible two-step mechanism for RNA interference (RNAi): an initiation step and an effector step.
a In the first step, input double-stranded (ds) RNA is processed into 21–23-nucleotide ‘guide sequences’. Whether they are single or double stranded remains an open question. An RNA amplification step (shaded box) has been suggested on the basis of the unusual properties of the interference phenomenon in whole animals, but this has not been reproduced definitively in vitro.
b The guide RNAs are incorporated into a nuclease complex, called the RNA-induced silencing complex (RISC), which acts in the second effector step to destroy mRNAs that are recognized by the guide RNAs through base-pairing interactions. We also suggest the incorporation of an active mechanism to search for homologous mRNAs.
优酷上的视频（中文字幕）
