2021年经济学人 人猴杂交(2)

The researchers began with 132 embryos² of the crab-eating macaque. Six days after fertilisation these were injected with human extended pluripotent stem cells, which can develop into any other cell type found in the body. Tagging the human cells with fluorescent³ markers allowed the researchers to track where in the developing embryo¹ they, and their descendants, went.

研究人员从食蟹猕猴的132个胚胎着手。在受精后的第六天向它们注射人类扩展多能干细胞（EPSC）。这些干细胞可以发育成嵌合体内的任何其他细胞类型。用荧光标记物标记人类细胞，研究人员就能够追踪这些细胞及其后代在发育的胚胎中的位置。

In the early stages of development, mammal embryos develop into four distinct cell types. Epiblasts go on to form the organism itself; hypoblasts develop into the yolk⁴ sac; trophectoderms become the placenta and extra-embryonic⁵ mesenchyme cells make a membrane⁶ that surrounds the embryo. The chimera's human cells made their way into all four types of tissue, though they were outnumbered in every case. No more than 7% of the epiblast was made up of human cells, and just 5% of the hypoblast (in other areas the numbers were lower still).

在发育的早期，哺乳动物的胚胎会形成四种不同的细胞类型。外胚层继续形成生物体本身；内胚层发育成卵黄囊；滋胚层变成胎盘；胚外间充质细胞形成包裹胚胎的膜。嵌合体中的人类细胞参与生成了所有四类组织，尽管在每一类中的数量都少于猴子细胞。人类细胞在外胚层中的占比不超过7％，在内胚层只有5％（在另两类中占比还要少）。

Joint⁷ venture

大胆接合

The cells' location seemed to influence which proteins they produced. Human cells in the chimera's epiblast behaved more like those found in human embryos than those found in monkey embryos. But that was not true of human hypoblast or extra-embryonic mesenchyme cells, both of which behaved more like monkey cells.

细胞所在的位置似乎会影响它们生成何种蛋白质。嵌合体外胚层中的人类细胞的行为更近似于人类胚胎细胞，而不像猴子胚胎细胞。但内胚层或胚外间充质细胞中的人类细胞的行为却都更像猴子细胞。

The monkey cells, in turn, were affected⁸ by the presence of the human ones. The researchers found 126 different sorts of cellto-cell interactions among monkey cells in the chimeric⁹ embryos, compared with just 19 in non-chimeric ones, as well as differences in the activity levels of many genes¹⁰.

反过来，猴子细胞也受到了人类细胞存在的影响。研究人员发现，嵌合胚胎中的猴子细胞之间有126种不同类型的细胞间相互作用，而在非嵌合体中只有19种。此外许多基因的活性水平也存在差异。

The cells were grown in a lab, which imposed limitations. The number of surviving embryos began falling by day 15. By day 20 none was left. But that was enough time for a process called gastrulation to take place. Gastrulation is a vital development stage in which embryonic cells become primed to form different organs and tissues. The human cells took longer to reach this point than the monkey ones did. But they managed nevertheless, providing more evidence that the human cells were not merely passive passengers, but were "mucking in" to help with the process of embryonic development.

这些细胞是在实验室里生长的，这带来了局限性。到了第15天，存活的胚胎数量开始下降。到第20天已一无所剩。但这段时间已经足以发生一个名为“原肠胚形成”的过程。原肠胚形成是一个至关重要的发育阶段，胚胎细胞在此期间准备好形成不同的器官和组织。人类细胞达到这个节点所花的时间比猴子细胞更久，但它们还是做到了。这就提供了更多证据，证明人类细胞不仅仅是被动的搭乘者，而是在“一同出力”帮助了胚胎的发育过程。

1 embryo   

n.胚胎，萌芽的事物

参考例句：

• They are engaging in an embryo research.他们正在进行一项胚胎研究。
• The project was barely in embryo.该计划只是个雏形。

2 embryos   

n.晶胚；胚，胚胎( embryo的名词复数 )

参考例句：

• Somatic cells of angiosperms enter a regenerative phase and behave like embryos. 被子植物体细胞进入一个生殖阶段，而且其行为象胚。 来自辞典例句
• Evolution can explain why human embryos look like gilled fishes. 进化论能够解释为什么人类的胚胎看起来象除去了内脏的鱼一样。 来自辞典例句

3 fluorescent   

adj.荧光的，发出荧光的

参考例句：

• They observed the deflections of the particles by allowing them to fall on a fluorescent screen.他们让粒子落在荧光屏上以观察他们的偏移。
• This fluorescent lighting certainly gives the food a peculiar color.这萤光灯当然增添了食物特别的色彩。

4 yolk   

n.蛋黄，卵黄

参考例句：

• This dish would be more delicious with some yolk powder.加点蛋黄粉，这道菜就会更好吃。
• Egg yolk serves as the emulsifying agent in salad dressing.在色拉调味时，蛋黄能作为乳化剂。

5 embryonic   

adj.胚胎的

参考例句：

• It is still in an embryonic stage.它还处于萌芽阶段。
• The plan,as yet,only exists in embryonic form.这个计划迄今为止还只是在酝酿之中。

6 membrane   

n.薄膜，膜皮，羊皮纸

参考例句：

• A vibrating membrane in the ear helps to convey sounds to the brain.耳膜的振动帮助声音传送到大脑。
• A plastic membrane serves as selective diffusion barrier.一层塑料薄膜起着选择性渗透屏障的作用。

7 joint   

adj.联合的，共同的；n.关节，接合处；v.连接，贴合

参考例句：

• I had a bad fall,which put my shoulder out of joint.我重重地摔了一跤，肩膀脫臼了。
• We wrote a letter in joint names.我们联名写了封信。

8 affected   

adj.不自然的，假装的

参考例句：

• She showed an affected interest in our subject.她假装对我们的课题感到兴趣。
• His manners are affected.他的态度不自然。

9 chimeric   

adj.妄想的，荒诞不经的

参考例句：

• High-intensity-type chimeric hedging may be gas-tight syringe safety connections, never loose. 高强度嵌合式套头，可与针筒安全气密式连接，绝不松脱。 来自互联网
• His utopia is not as chimeric commonwealth but a practical improvement on what already exists. 他的乌托邦不是空想的联邦，而是对那些已经存在的联邦实际改进。 来自互联网

10 genes   

n.基因( gene的名词复数 )

参考例句：

• You have good genes from your parents, so you should live a long time. 你从父母那儿获得优良的基因，所以能够活得很长。 来自《简明英汉词典》
• Differences will help to reveal the functions of the genes. 它们间的差异将会帮助我们揭开基因多种功能。 来自英汉非文学 - 生命科学 - 生物技术的世纪