【经济学人】基因工程也更新|2017.05.25|总第924期

THE central idea of synthetic biology is that living cells can be programmed in the same way that computers can, in order to make them do things and produce compounds that their natural counterparts do not. As with computers, though, scientists need a way to control their creations. To date, that has been done with chemical signals. In a paper published in Nature Chemical Biology, Christopher Voigt, a biologist at the Massachusetts Institute of Technology, describes an alternative. Instead of chemicals, he and his colleagues demonstrate how to control customised cells with coloured light.

合成生物学的核心观念就是活细胞可以跟计算机一样，可通过编程使它们完成一些同类无法完成的事情，并生产复合物。然而与计算机一样，科学家需要一种控制产物的方法，目前都是通过化学信号实现的。麻省理工学院生物学家Christopher Voigt，在<>杂志上发表的文章提供了一种可供选择的方法。他和同事也说明了在不用化学物质的情况下，是如何用色光来控制定制细胞的。

• customise  v.自定义

Engineering cells to respond to light is not a new idea. The general approach is called optogenetics, and it has become a popular technique for controlling nerve cells in neuroscience. But Dr Voigt is not interested in nerve cells. In 2005 he altered four genes in a strain of Escherichia coli bacteria, which gave the creatures the ability to respond to light and darkness by becoming lighter or darker in colour themselves. The state of the art has advanced since then. This time Dr Voigt wanted to see if he could give his bacterial charges—which normally live in the human gut, and therefore rarely see light of any sort—the ability to sense colour.

细胞光应答工程不是一个新想法。一般的方法被是利用光遗传学技术，这已成为神经科学控制神经细胞的热门技术。但Voigt博士对神经细胞不感兴趣。2005年，他稍微改变了大肠杆菌菌株中的四个基因，这使得生物体能够根据光线明亮程度改变自身颜色亮度。从那之后，这一领域的技术水平在不断提升。这一次Voigt博士想知道他是否能为通常生活在很少能看到任何光线的人类肠道中的细菌带来改变，赋予其一种感知颜色的能力。

• optogenetics  光遗传学

• Escherichia coli  [基医]大肠杆菌

That meant tinkering with 18 different genes containing more than 46,000 base pairs of DNA. These changes persuaded the cells to build three different kinds of light sensors that are similar in structure to the photoreceptors found in plants and algae. These sensors allow their owners to track things like the time of day and the seasons, and to plan their reproduction accordingly. One sensor, for instance, harvested from a type of algae, switches on when struck by light with a wavelength of 535 nanometres (which humans would perceive as green) and then off again when exposed to light of a longer, redder wavelength. Other sensors responded to light at the blue and red ends of the visible spectrum.

这意味着要修改18个不同基因中的46000多对碱基。这些变化会使细胞构建了三种不同类型的光感器，它们与植物和藻类中的光感受器相似。这些传感器使他们的宿主能感受到时间和季节的变化，并根据这些变化相应地做出繁殖计划。例如，从一种藻类中获取的光感器在受到波长为535nm的光照射时就会工作（人视觉下绿色），当接收的光线波长为较长的红色光时就会停止工作。其他传感器会对可见光谱中的蓝色与红色为之间的光作出相应的反应。

• tinkering with   修复、提升……

• photoreceptor  n.光感受器

• algae  n.藻类

• visible spectrum  可见光谱

Those photoreceptors, in turn, control the expression of certain bacterial genes. For demonstration purposes, Dr Voigt’s prototype E. coli have been designed to produce enzymes that cause the bacteria to become the same colour as the light being shone upon them. So, if a plate of the bacteria is struck by a beam of green light, the plate becomes green. If a plate has an image composed of red, green and blue projected upon it, the plate will reproduce the projection（读者试译）

这些光感受器会反过来控制某些细菌基因的表达。为进行演示，Voigt博士展示了专门设计的大肠杆菌原型，用来使细菌产生一些酶，这些酶能使细菌的颜色变得与照射光一样。(期待您的翻译，明天将会有针对这句话的长难句解析哟~)

Such artistry is the tip of the iceberg: the light sensors could be used to control genes that make all sorts of different chemicals. Scientists have toyed with the idea of using vats of genetically altered bacteria to produce things like artificial sweeteners or drugs. But getting the chemistry right requires that the bugs execute several chemical reactions in exactly the right sequence. Doing that with chemicals is expensive, and fiddly, since the chemicals take time to circulate around the vat. Dr Voigt imagines instead vats fitted with coloured lights that wink on and off in sequence. It would look, he jokes, a bit like a bacterial disco. Such single-celled revellers could yet be the future of chemical manufacturing.

这样的技术只是冰山一角：光感应器可以用来控制生产各种不同化学物质的基因。科学家们已经有了利用基因被修改过的细菌生产像人工甜味剂或药物的想法。但获得合适的化学品需要细菌以特定的顺序进行化学反应。利用化学物质进行化学反应来生产特定化学品成本高、精度要求也比较高，而且化学物质在制剂桶旁循环也需要一定的时间。Voigt博士设想，把有色光照射到制剂桶，然后就会依次间断闪烁。他开玩笑说，这看起来有点像细菌的迪斯科。这种单细胞也许会是化学制造业的未来。

• fiddly  adj.要求高精度的

翻译 ▍E-K-2 hua外音

审核 ▍E-K-2-0云图

图文编辑 ▍毛毛

责任编辑 ▍毛毛