Experimental biologyFantastic beasts and how to make themResearchers have created embryos from a mix of monkey cells and human onesThe ancient greeks were good at inventing fantastical animals.The chimera, for instance, was "a thing of immortal make, not human, lion-fronted and snake behind, a goat in the middle".It was eventually slain by Bellerophon, with help from his flying horse.Not all chimeras are mythological. To biologists, the term describes organisms whose bodies consist of cells from two distinct lineages.In twin pregnancies, for example, one twin can occasionally absorb the other. The resulting individual is built from cells with separate genomes.A 2019 forensic-science conference discussed the case of a man who had received a bone-marrow transplant.Since bone marrow produces blood cells, subsequent DNA tests on the man's blood matched his donor's genome, not his own.(More unexpectedly, the donor's DNA also turned out to be present in swabs taken from the man's cheeks, and in his semen.)For several decades scientists have been experimenting with cross-species chimeras, organisms which, as in the Greek myths, are composites of different animals.They have created mouse-rats, sheep-goats and chicken-quails.
实验生物学神兽以及如何创造神兽研究人员创造出了半人半猴的胚胎古希腊人擅长想象神奇动物。比如，客迈拉是“一种不朽的创造物，非人类，狮头，蛇尾，羊身”。柏勒洛丰在他的飞马的助力下，最终将其杀死。并非所有客迈拉都是神化虚构。在生物学家口中，这个词意指那些身体由来自两个不同谱系的细胞组成的生物。例如，在双胎妊娠中，一个胎儿偶尔会把另一个“吸收”掉，最后出生的个体是由具有不同基因组的细胞组成的。2019年，一次法医科学会议讨论了一名男性接受骨髓移植的案例。由于骨髓产生血细胞，后续对这名男子的血液DNA检测显示它匹配的是供体的基因组，而不是他自身的基因组。（更出人意料的是，在他的口腔拭子和精液中也发现了供体的DNA。）几十年来，科学家一直在试验创造跨物种嵌合体――和希腊神话中的神兽一样，它是不同动物的复合体。他们创造了小鼠-大鼠、绵羊-山羊以及鸡-鹌鹑嵌合体。
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