事實脈絡
解讀與影響
从技术路径来看，该研究的关键在于利用 CRISPR 精确移除 Y 染色体，使原本雄性（XY）的胚胎在发育方向上转为雌性（XX）。报道指出，这一方法已在实验室中成功实现雄性小鼠的雌性克隆。原文未提供该研究的具体发表期刊、作者团队及实验成功率等细节，但这一方向本身指向一个长期存在的技术瓶颈：在克隆或辅助生殖中，可供使用的供体细胞性别往往受限，而性别转换手段有望扩大可用细胞来源。
报道同时将讨论引向克隆技术的双重前景。一方面，该技术可能用于濒危物种保护——当某一物种仅存雄性个体或雄性细胞样本时，通过性别转换与克隆结合，理论上可重建可繁殖的雌性个体，为种群恢复提供新路径。另一方面，报道也提及了更具争议性的设想：利用类似技术制造人类“器官囊”（organ sacks），即通过克隆与基因编辑培育用于器官获取的生物体。原文未详细展开这一设想的伦理讨论或技术可行性，但将其作为克隆技术可能走向的一个方向提出。
值得注意的是，MIT Tech Review 的报道将物种保护与人类器官获取置于同一技术框架下讨论，反映出基因编辑与克隆技术正在从基础研究加速走向应用场景。不过，原文未提供关于人类应用的任何实验数据或监管进展，相关讨论仍处于设想层面。对于读者而言，这一报道的核心价值在于提示：性别决定机制的基因编辑操作，正在为克隆技术打开此前难以触及的应用空间。
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來源原文
This week I spoke to scientists who have found a way to turn male mouse embryos female. They’ve developed a CRISPR-based approach to essentially cut out the Y chromosome. It allowed them to create female clones of male mice.
That’s right: female animals that are genetically identical to males, except for the missing Y chromosome. Takashi Ishiuchi, a reproductive biologist at the University of Yamanashi who co-led the work, told me it felt a bit like sci-fi.
Ishiuchi and his colleague Shogo Matoba of the Riken BioResource Research Center hope their approach could be helpful in conservation efforts, especially in cases where we might have only a few individuals of a species left. But cloning has multiple uses, ranging from the cool to the outright creepy.
We can’t talk about cloning without mentioning Dolly, the celebrity sheep born in 1996 and the first mammal successfully cloned from an adult cell. In that case, scientists took the DNA-containing nucleus of an adult mammary cell from one sheep and transferred it into an egg cell that had had its own nucleus removed. The resulting embryo was transferred to a surrogate sheep, which gave birth to Dolly—an animal genetically identical to the DNA donor.
The scientists behind that work were interested in genetically modifying livestock. Farmers have essentially been doing this for thousands of years through selective breeding, but cloning allows scientists to create genetic replicas of animals with desirable traits.
Cloning is also being used to replicate deceased pets, including, famously, those of Barbra Streisand and Tom Brady, among others. For a price somewhere in the tens of thousands of dollars, a company can take cells from your pet and turn them into a living, breathing clone.
Considering that cloning also requires egg cells from another animal, and a surrogate animal to carry the pregnancy, not everyone is on board with this, especially since there is no medical or environmental need for the procedures. One bioethicist, Jessica Pierce, has described this aspect of dog cloning as “the exploitation of the canine underclass.”
The case for cloning is stronger when it comes to conservation—where some argue there is environmental value.
Scientists have been preserving animal tissues for years. Some of these tissues are cryopreserved at low temperatures in “frozen zoos.” The facility at the San Diego Zoo, for example, currently has cells from over 1,300 species. Some of these samples were taken decades ago.
Preserved tissues like these have enabled scientists to create clones of animals considered close to extinction, including black-footed ferrets and Przewalski’s horse. But they might also help us bring back extinct animals.
In 2009, researchers in Spain described how they’d cloned an extinct wild goat, the Pyrenean ibex, using skin cells that had been cryopreserved a decade earlier. In that research, the team used egg cells from domestic goats to create a total of 439 embryos. Ultimately, only one goat—a female—was born. She died minutes later because of a defect in her lungs.
Poor Pyrenean ibex. It’s the only animal we know of that has gone extinct twice.
The biotech company Colossal Biosciences is hoping to use old—and potentially ancient—genetic material to bring back long-extinct species like the thylacine and woolly mammoth. So far, the company’s efforts have largely involved modifying the genomes of modern-day animals.
Technically, it’s also possible to clone humans. As far as we know, no one has done it. But some have played with the idea. One biotech startup founder has pitched an idea for “brainless clones”—human clones that lack a brain but contain all the organs people might need to replace their own in future. My colleague Antonio Regalado described that pitch in March. (I had to pause eating my lunch while rereading it.)
Scientists have done a hell of a lot with cloning over the last few decades. I’m excited—but also slightly nervous—about what the coming decades will bring.
This article first appeared in The Checkup, MIT Technology Review’s weekly biotech newsletter. To receive it in your inbox every Thursday, and read articles like this first, sign up here.