本文選自經濟學人2019年1月17日文章。在過去的數十億年中，自然界只存在 4 種鹼基——腺嘌呤（A）、胸腺嘧啶（T）、胞嘧啶（C）和鳥嘌呤。現在，研究人員打破了這些規則，在 Floyd Romesberg 位於聖地牙哥的實驗室，科學家通過擴展基因編碼，在培養的細菌中增加了一對「超自然」的鹼基對：X 和 Y。更令人驚奇的是，細菌可以利用這對超自然鹼基對編碼新蛋白！這一突破一舉改變了大眾對於生命遺傳信息的認知，堪稱「顛覆遺傳密碼」的成果。
由於篇幅較長，本文節選原文標題和全文重點段落進行精講，幫助大家提高英語閱讀和寫作能力。
英文原文
Extending the genetic code
Adding new DNA letters make novel proteins possible
One such, a cancer drug, is now in development
Jan 17th 2019 | LA JOLLA, CALIFORNIA
THE FUZZY specks growing on discs of jelly in Floyd Romesberg’s lab at Scripps Research in La Jolla look much like any other culture of E. coli. But appearances deceive—for the DNA of these bacteria is written in an alphabet that has six chemical letters instead of the usual four.
Every other organism on Earth relies on a quartet of genetic bases: A (adenine), C (cytosine), T (thymine) and G (guanine). These fit together in pairs inside a double-stranded DNA molecule, A matching T and C, G. But in 2014 Dr Romesberg announced that he had synthesised a new, unnatural, base pair, dubbed X and Y, and slipped them into the genome of E. coli as well.
Kept supplied with sufficient quantities of X and Y, the new cells faithfully replicated the enhanced DNA—and, crucially, their descendants continued to do so, too. Since then, Dr Romesberg and his colleagues have been encouraging their new, 「semisynthetic」 cells to use the expanded alphabet to make proteins that could not previously have existed, and which might have properties that are both novel and useful. Now they think they have found one. In collaboration with a spin-off firm called Synthorx, they hope to create a less toxic and more effective version of a cancer drug called interleukin-2.
選文精讀
Extending the genetic code 擴展遺傳密碼
Adding new DNA letters make novel proteins possible 新增的DNA鹼基讓產生新的蛋白質成為可能
One such, a cancer drug, is now in development 其中一種抗癌藥物正在研發中
THE FUZZY specks growing on discs of jelly in Floyd Romesberg’s lab at Scripps Research in La Jolla look much like any other culture of E. coli. But appearances deceive—for the DNA of these bacteria is written in an alphabet that has six chemical letters instead of the usual four.
fuzzy: 模糊的(indistinct; blurred:)，圖片模糊，可以說「the picture is fuzzy」，可與「vague」互換；此外，fuzzy還有毛茸茸的意思（of the nature of or resembling fuzz: a soft, fuzzy material.）。
speck: 汙點、小顆粒，與「blot, particle, stain」等詞同意。
E. coli: 大腸桿菌
deceive: 欺騙（to mislead by a false appearance or statement; delude: They deceived the enemy by disguising the destroyer as a freighter.）
在拉霍亞的斯克裡普斯研究中心的弗洛伊德·羅梅斯伯格的實驗室裡，膠盤上生長著的模糊的斑點看起來很像大腸桿菌培養物。不要被它的外表欺騙了，因為這些細菌的DNA是用6個鹼基字母組成，而不是通常的4個。
Every other organism on Earth relies on a quartet of genetic bases: A (adenine), C (cytosine), T (thymine) and G (guanine). These fit together in pairs inside a double-stranded DNA molecule, A matching T and C, G. But in 2014 Dr Romesberg announced that he had synthesised a new, unnatural, base pair, dubbed X and Y, and slipped them into the genome of E. coli as well.
quartet: 四重奏，這裡指四個鹼基。
adenine: 腺嘌呤；cytosine: 胞嘧啶；thymine: 胸腺嘧啶；guanine: 鳥嘌呤
double-stranded: 雙鏈
base pair: 鹼基對
dub: 把...稱為（to invest with any name, character, dignity, or title; style; name; call: He was dubbed a hero.）；此外，這個詞還有「配音；打擊」的意思。
slip into: 注入
genome: 基因組
地球上的其他所有生物都是基於四種鹼基：A(腺嘌呤)、C(胞嘧啶)、T(胸腺嘧啶)和G(鳥嘌呤)。它們成對地組合在一個雙鏈DNA分子中，A和T配對, C和G配對。但是2014年，Romesberg博士宣布他已經合成了一個新的，超自然的鹼基對，稱為X和Y，並將它們植入大腸桿菌的基因組中。
Kept supplied with sufficient quantities of X and Y, the new cells faithfully replicated the enhanced DNA—and, crucially, their descendants continued to do so, too. Since then, Dr Romesberg and his colleagues have been encouraging their new, 「semisynthetic」 cells to use the expanded alphabet to make proteins that could not previously have existed, and which might have properties that are both novel and useful. Now they think they have found one. In collaboration with a spin-off firm called Synthorx, they hope to create a less toxic and more effective version of a cancer drug called interleukin-2.
如果提供足夠數量的X和Y，新細胞會不停的複製強化的DNA——關鍵的是，它們的後代也會不停的複製。此後，Romesberg博士和他的同事們一直在嘗試用這種新的，「半合成」細胞使用新增的鹼基來製造以前不存在的蛋白質，而這些蛋白質可能具有新的和有用的特性。現在他們認為自己到了一個。他們與一家名為Synthorx的分拆公司合作，希望開發出一種毒性更小、更有效的抗癌藥物——白介素-2。
將本文分享至朋友圈，發送截圖至本公眾號，小編會將英文原文閱讀連結發給大家。因需求人數較多，請耐心等待，感謝閱讀！
英語學習交流，請掃描下方二維碼，加主編東籬君微信，備註「英文雜誌精選」