英语沙塔|经济学人精读|为抗癌造福的大肠杆菌新基因

2019-01-27 本文已影响0人英语沙塔电影英语学习

本文节选自《经济学人》2019.01.19期，Science and technology版块中的一篇关于基因与抗癌药物的报道。

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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 specks：毛绒绒的斑点

discs of jelly：圆盘培养皿里的凝胶

culture：（细胞、细菌）培养。如 a culture of cells from tumor：肿瘤细胞的培养

E. coli：大肠杆菌

appearances deceive：表象会欺骗

is written in ……：是用……写的

alphabet：字母表，这里是指碱基，我们熟知的是A/G/C/T四个

instead of：代替，而不是

拉由拉市弗洛伊德·罗姆斯伯格实验室那些圆盘培养皿里的毛茸茸的斑点，和其他培养的大肠杆菌如出一辙。但是，外表总是会骗人的—这些大肠杆菌的DNA是由六个字母编写的，而不是我们通常所知的四个

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.

a quartet of：四个

fit together：组合在一起

in pairs：成对地

double-stranded：双链，双股的

base pair：碱基对

slipped into：悄悄溜进。slip sth into，加入，插入

genome of ……：……的基因组

地方上的其他生物都依靠四个遗传基础：A（腺嘌呤）、C（胞嘧啶）、T（胸腺嘧啶）、G（鸟嘌呤）。这些碱基在双链DNA分子中成对组合，A和T配对，C和G配对。但在2014年，罗姆斯伯格声称他合成了一种新的、非自然的碱基对，为X和Y，并将它们也加入了大肠杆菌的基因组中。

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.

supplied with：供给

faithfully：除了忠诚的意思，还有【写作推荐】准确地；如实地；仔细地accurately; carefully

crucially：替换importantly

descendants：后代，这里指产生的子细胞。

encouraging cells to ……：促进细胞……。如encourage economic growth促进经济增长，不是鼓励激励的意思。

In collaboration with：与……合作【写作推荐】

spin-off：副产品

a version of：一种（药物），一个版本

保持供给足够的X和Y碱基，这种新的细胞准确地复制改进的DNA，关键的是，它们的子代同样如此。从那时起，罗姆斯伯格和他的同事们就开始促进这些新的“半合成”细胞，利用扩展的碱基来合成过去不存在的蛋白质，这些蛋白可能拥有一些新的特性和功能。现在，他们认为他们找到了一种新蛋白。通过与副产品公司Synthorx合作，他们希望能制造出一种毒性低，更有效的抗癌药物—白细胞介素-2

Dr Romesberg and Laura Shawver, Synthorx’s boss, picked interleukin-2 in particularto work onbecause of the mismatch between its potential and its reality. Though it is useless at low doses—actually suppressing the immune response to tumours rather than enhancing it—at high doses it is extremely effective at promoting such an anti-tumour response. Unfortunately, a side-effect is that it damages the walls of blood vessels, causing plasma to leak out. When this happens in the lungs, the patient may drown. As Dr Shawver puts it, some people have been cured of their cancers thanks to interleukin-2, “but they have to live to tell the tale”.

in particular：特地、特别

work on：致力于，研究

mismatch between A and B：误配，搭配不当

is extremely effective at promoting ……：在促进……方面非常有效

leak out：泄露，漏出

As sb puts it：正如某人所说【写作推荐】引经据典时的句式

罗姆斯伯格和Synthorx的老板劳拉·肖瓦特地选择白细胞介素-2进行研究，因为其潜力与其现实效果不相配。尽管低剂量白细胞介素没有效果—事实上会抑制免疫系统对肿瘤细胞的反应而不是增强—但高剂量时，却能高效促进抗肿瘤反应。不幸的是，它的副作用之一是会损伤血管壁，这会使得血浆外渗。当这种情况发生在肺部时，病人会窒息而死。正如肖瓦博士所说：“多亏了白细胞介素-2，人们得以幸存于癌症之中，但他们需要活下来才能讲述这个故事

Interleukin-2 works by binding to, and stimulating the activity of, immune-system cells called lymphocytes. The receptor it attaches itself to on a lymphocyte’s surface is made of three units: alpha, beta and gamma. Immune cells with all three form a strong bond to interleukin-2, and it is this which triggers the toxic effect. If interleukin-2 can be induced to bind only to the beta and gamma units, however, the toxicity goes away. And that, experiments have shown, can be done by attaching polyethylene glycol (PEG) molecules to it.

works by：通过……发挥作用

binding to：绑定，结合

is made of：由……组成。

Triggers：触发，发动。

be induced to：被引诱、诱导

go away：除了走开，还有消失的意思

白细胞介素通过结合并刺激免疫系统细胞—淋巴细胞的活动发挥作用，其依附的位于淋巴细胞表面的受体由3个亚基组成：α、β和γ。白细胞介素与免疫细胞通过三个亚基形成牢固的联系，而这也触发了毒性反应。但是，如果白细胞介素-2可以被诱导只与β和γ亚基联接，则毒性反应就会消失。实验证实，这可以通过附加聚乙二醇分子实现。

The trick is to make the PEGS stick. This is where the extended genetic alphabet comes in. Using it, Synthorx has created versions of interleukin-2 to which PEGS attach themselves spontaneouslyin just the right place to stop them linking to the alpha unit. Tested on mice, the modified molecule has exactly the desired anti-tumour effects. Synthorx plans to ask permission forhuman trials later this year.

The trick is：关键是【写作推荐】the most important thing is

This is …… comes in：这是……派上用场的地方【写作推荐】介绍某种东西的功能时

Spontaneously：自发地，自主地。

Desired：期望的，渴望的

ask permission for：请求允许，请求批准

关键在于制作聚乙二醇标定物，扩展的碱基字母表的作用就在于此。通过新的字母表，Synthorx创造了一种新的白细胞介素-2，使得聚乙二醇分子自发地结合至正确的位置，使得其不能与α受体结合。经过小鼠实验证明，改良的分子有预期的抗肿瘤效果。Synthorx公司计划请求批准今年晚些时候可以进行人体实验。

Synthorx already has synthetic versions of several others in the pipeline. And the wider possibilities are endless. The beauty of Dr Romesberg’s system is that it works without disrupting a cell’s normal function, making it possible to hijack cells’ factory-like properties to produce almost any “designer” protein. These might have properties not normally seen in organic molecules—semi-conductor proteins that can be woven into soft materials, perhaps.

in the pipeline：在准备中

The beauty of：……的优势，……的精妙之处在于【写作推荐】

making it possible to：使……成为可能

Hijack：劫持（交通工具）；操纵（使符合自己的意图），这里形象地说明人类利用细胞的功能来实现人们预期的目的，可翻译为利用【写作推荐】

Synthorx公司已经有多种合成版本的药物在准备中，且广阔的可能性无穷无尽。罗姆斯波特系统的优势在于它不会破坏细胞的正常功能，而是通过利用细胞的工厂特性，使细胞合成几乎任何一种“设计”蛋白成为可能。这些蛋白可能会有一些正常有机分子所没有的特性—半导体蛋白或许可以被编织进柔软的材料

Nor need those who worry about genetically modified organisms escaping from the lab fret about this particular system. Without a steady supply of x and y, any escapee would not get far in the wild.

Nor need ……：人们也不用担心，中间省略号为those引导的定语从句，简单来看，就是Nor need people fret about this particular system。一个倒装结构【写作推荐】句式

fret about：担忧【写作推荐】=worry about

那些担心基因改良的有机物会逃离实验室的人也不用担忧，没有稳定提供的X和Y碱基，任何偷逃者在野外环境都无法走太远。

总结