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| Every cell in our body contains a copy of our genome(基因组)--over 20,000 genes, 3 billion letters of DNA. DNA consists of two strings twisted into a double helix and held together by a simple pairing rule -- A pairs with T and G pairs with C. Our genes shape who we are as individuals and as a species. Genes also have profound effects on health. And thanks to advances in DNA sequencing, researchers have identified thousands of genes that affect our risk of disease. To understand how genes work, researchers need ways to control them. Changing genes and living cells are not easy. But recently, a new method has been developed that promised to dramatically improve our ability to edit the DNA of any species, including humans.
在我们的身体每一个细胞都包含一份我们的基因组(基因组)——超过20000个基因,30亿个字母的DNA。扭成一个双螺旋DNA包含两个字符串,由一个简单的配对规则——一个对与T和G双c基因形状我们个人和作为一个物种。基因对健康也有深远的影响。由于DNA测序技术的发展,研究人员已经确定了成千上万的基因,影响我们的疾病的风险。为了理解基因是如何工作的,研究人员需要一些方法来控制它们。改变基因和活细胞是不容易的。但最近,科学家发明了一种新方法,承诺将大大提高我们编辑任何物种的DNA的能力,包括人类。
The CRISPR method is based on a natural system used by bacteria to protect themselves from infection by viruses. When the bacteria detects the presents of virus DNA, it produces two types of short RNA, one of which contains sequence that matches that of the invading virus. These two RNAs from a complex with a protein called CAS 9. CAS 9 is a nuclease(核酸酶), a type of enzyme that can cut DNA. When the matching sequence, known as a guide RNA, finds its target within the viral genome, the CAS 9 cuts the target DNA, disabling the virus.
CRISPR方法是基于自然系统所使用的保护自己免受细菌感染病毒。当细菌检测到病毒DNA的礼物,它产生两种类型的短RNA,其中一个包含入侵病毒的序列相匹配。这两个rna从一个复杂的蛋白质称为CAS 9。中科院9是一个核酸酶(核酸酶),一种酶,这种酶能降低DNA。当匹配序列,称为指南RNA,发现其目标在病毒基因组,CAS 9削减目标DNA,禁用病毒。
Over the past few years, researchers studying the system realized that it could be engineered to cut not just viral DNA but any DNA sequence at a precisely chosen location by changing the guide RNA to match the target. And this can be done not just in a test tube, but also within the nucleus of a living cell. Once inside the nucleus, the resulting complex will lock onto a short sequence known as the PAM.
在过去的几年中,研究人员系统意识到它可以改造不仅减少病毒DNA,任何DNA序列精确选择位置通过改变引导RNA与目标相匹配。这不仅可以在试管中,但是也活细胞的细胞核内。一旦进入细胞核,由此产生的复杂将锁定一个短序列称为PAM。
The CAS 9 will unzip the DNA, and matches to its target RNA. If the match is complete, the CAS 9 will use two tiny molecular scissors to cut the DNA. When this happens, the cell tries to repair the cut. But the repair processes error-prone, leading to mutations(突变) that can disable the gene, allowing researchers to understand its function. These mutations are random, but sometimes researchers need to be more precise. For example, by replacing the muton gene with the healthy copy. This can be done by adding another piece of DNA that carries the desired sequence. Once the CRIPSR system has made a cut, this DNA template(模板) can pair up(配对) with a cut ends, recombining and replacing the original sequence with the new version.
CAS 9将解压DNA、RNA和匹配目标。如果匹配完成,CAS 9将使用两个小分子剪刀切断DNA。当这种情况发生时,细胞试图修复。但修复过程出错,导致突变(突变),可以禁用该基因,让研究人员了解其功能。这些突变是随机的,但有时人员需要更精确。例如,通过替换突变子基因与健康的副本。可以通过添加另一个DNA片段,携带所需的序列。一旦CRIPSR系统使得削减,这DNA模板(模板)可以配对(配对)将结束,重组和新版本替换原有的序列。
All this can be done in cultured cells including stem cells that can give rise to many different cell types. It can also be done in a fertilized egg(受精卵), allowing the creation of transgenic animals with targeted mutations. And unlike previous methods, CRISPR can be used to target many genes at once. A big advantage for studying in complex human diseases that are caused not by a single mutation, but by many genes acting together. These methods are being improved rapidly and will have many applications in basic research, in drug development, in agriculture, and perhaps eventually for treating human patients with genetic disease.
所有这一切都可以通过培养细胞包括干细胞,可以产生许多不同的细胞类型。也可以做在一个受精卵(受精卵),允许建立转基因动物和有针对性的突变。和以前的方法不同,CRISPR可用于目标许多基因。研究在复杂的人类疾病的一大优势,而不是单一突变引起的,而是由许多基因一起表演。这些方法正在迅速改善,将会有许多应用基础研究,在药物开发,农业,或许最终治疗人类遗传性疾病患者。
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