新的基因編輯技術誕生
Scientists in the US have developed a powerful new genome editing system that could offer significantly more precision and efficiency than the current CRISPR standard.
美國科學家已研發出強大的新的基因組編輯系統，顯著提高目前CRISPR標準的精度和效率。While CRISPR-Cas9 is a revolutionary medical technology that lay the modern foundations for editing genetic code – including variants associated with disease – there have long been concerns over its potential for imprecision.
雖然CRISPR-Cas9是革命性的醫療技術，爲編輯包括與疾病相關的變異在內的遺傳密碼奠定了現代基礎，但一直存在對其潛在的不精確性的擔憂。Specifically, many fear that CRISPR-Cas9 editing carries the potential to introduce errors in the form of uncontrolled insertions and deletions in genetic code, called indels.
具體來說就是很多人害怕CRISPR-Cas9編輯有可能在被稱爲索引的遺傳密碼中不受控制的插入和刪除信息從而導致錯誤。
Researchers say the new system, dubbed 'prime editing' by its inventors at the Broad Institute of MIT and Harvard University, could change the game thanks to a new protein that enables high-precision edits of genetic targets.
研究人員說被麻省理工學院和哈佛大學的布羅德研究所的發明者稱爲“先導編輯”的這一新系統能改變基因，有一種新型蛋白質使研究人員可以對目標基因進行高精度編輯。
"A major aspiration in the molecular life sciences is the ability to precisely make any change to the genome in any location," says genome biologist David Liu from the the Broad Institute.
布羅德研究所的基因組生物學家David Liu說：“分子生命科學的一個主要目標是能精確改變任何位置的基因組。”"We're not aware of another editing technology in mammalian cells that offers this level of versatility and precision with so few byproducts."
“我們不知道有其他對哺乳動物細胞進行編輯的技術能像這一技術一樣用途廣泛、精度高，而且副作用這麼少。”The basis of the new prime editing method is an enzyme called reverse transcriptase. The CRISPR system also uses an enzyme – Cas9 – to cut DNA strands, so that alternative genetic code can be inserted.
這一新的先導編輯方法的基礎是被稱爲逆轉錄酶的酶，CRISPR系統也利用這種Cas9酶切割DNA鏈，插入替代遺傳密碼。Now, thanks to reverse transcriptase, which is used in conjunction with Cas9 in prime editing, genomic editing has been upgraded again.
現在多虧有了逆轉錄酶，基因組編輯再次升級了。逆轉錄酶與Cas9一起被用於先導編輯。In prime editing, a guide RNA called pegRNA guides a modified form of the Cas9 enzyme to snip only a single strand of DNA (preventing the double-strand breaks that can induce unintended disruptions).
先導編輯中名爲pegRNA的引導RNA指引修改過的Cas9酶只剪斷一條DNA鏈（避免雙鏈斷裂導致意外中斷）。After this, the reverse transcriptase enzyme directly copies edited genetic information contained in the pegRNA to the targeted genomic site.
然後逆轉錄酶直接將pegRNA中編輯過的基因信息複製到基因組的目標位置。
