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Scientists Just Successfully Bred Mice From Two Male Parents For the First Time, But It Didn't End Well
19 October 2018
Scientists say they may have completed yet another piece of the puzzle that could lead to same-sex partners someday being able to bear genetic offspring.
However, it’s only been attempted in mice, and experts say there’s a long way to go before it could even be considered for humans.
<p><span style="font-weight: 400;">While living mice produced by same-sex mouse partners have been born </span><a href="https://www.nature.com/articles/nature02402"><span style="font-weight: 400;">before</span></a><span style="font-weight: 400;">, the process has only been successful with two females. A Chinese </span><a href="https://www.sciencedirect.com/science/article/pii/S1934590918304417?via%3Dihub"><span style="font-weight: 400;">study</span></a><span style="font-weight: 400;"> published in October in the journal </span><i><span style="font-weight: 400;">Cell Stem Cell</span></i><span style="font-weight: 400;"> reports, though, that for the first time living pups have been produced from two males.</span></p><p><div id="insticator-container" class="embedid-ee1b1245-7f34-4d5c-8a70-c8be74fe7696"><div id="div-insticator-ad-1"></div><div id="insticator-embed"></div><div id="div-insticator-ad-2"></div><script data-cfasync="false" type="text/javascript">Insticator.ad.loadAd("div-insticator-ad-1");Insticator.ad.loadAd("div-insticator-ad-2");Insticator.load("em",{id : "ee1b1245-7f34-4d5c-8a70-c8be74fe7696"})</script></div></p><p><span style="font-weight: 400;">Typically, when placental mammals reproduce, the sperm and the egg work together in what’s called “imprinting,” when parts of the mother's DNA and parts of the father's DNA get different “tags” that affect how they will work in the offspring.</span></p><p><span style="font-weight: 400;">For the experiment, scientists cut out the genes that carried these kinds of imprinting-dependent tags — for females they found they had to cut three, and for males, seven. The research team ultimately made 200 attempts at creating mouse pups with two mothers, and succeeded 27 times.</span></p><p><div data-conversation-spotlight=""></div></p><p><span style="font-weight: 400;">However, it took 500 attempts to make mouse pups with two fathers, resulting in 12 live births. And, unlike the female mice’s babies, none of the males’ offspring survived to adulthood. In fact, only two lived longer than 48 hours.</span></p><p><span style="font-weight: 400;">Not exactly surprising, given that offspring produced by two males is virtually unheard of in nature, while some fish, frogs and lizards — Komodo dragons, for example — can naturally produce young with two females.</span></p><p><span style="font-weight: 400;">“To make an individual, you have to have an egg; males don't have eggs,” Richard Behringer, a developmental biologist at the University of Texas, </span><a href="https://www.nationalgeographic.com/science/2018/10/news-gene-editing-crispr-mice-stem-cells/"><span style="font-weight: 400;">told</span></a> <i><span style="font-weight: 400;">National Geographic</span></i><span style="font-weight: 400;">.</span></p><p><span style="font-weight: 400;">Edited stem cells can simply be inserted into the egg of another female, but for two males, the process is quite a bit more complicated. To make “bipaternal” offspring, the scientists must inject sperm and the edited stem cells into an immature egg without a nucleus, the component where most genetic material is stored. The egg then has to be matured outside a surrogate mouse before it can be successfully implanted in her uterus.</span></p><p></p><p><span style="font-weight: 400;">Even though the female-offspring mice appeared healthy and even were able to bear their own young, the effects of gene editing on their long-term health have yet to be known.</span></p><p><span style="font-weight: 400;">“When you do the gene targeting, you may get some unintended side effects. You may alter other sequences which you didn't mean to alter,” </span><span style="font-weight: 400;">Azim Surani</span><span style="font-weight: 400;">, a developmental biologist at the University of Cambridge, </span><a href="https://www.nationalgeographic.com/science/2018/10/news-gene-editing-crispr-mice-stem-cells/"><span style="font-weight: 400;">told</span></a> <i><span style="font-weight: 400;">National Geographic</span></i><span style="font-weight: 400;">. These changes are then passed down to the next generation, where harmful effects could eventually emerge.</span></p><p><span style="font-weight: 400;">Not only that, but the ethical considerations of genetically altered children, especially considering the as-yet-unclear implications of gene editing in the adult mice, are immense and potentially impassable. </span></p><p><span style="font-weight: 400;">“It is never too much to emphasize the risks, and the importance of safety, before any human experiment is involved,” Wei Li at the Chinese Academy of Sciences in Beijing, one of the study authors, </span><a href="https://www.newscientist.com/article/2182212-we-are-a-step-closer-to-making-babies-with-same-sex-genetic-parents/?utm_medium=SOC&utm_source=Facebook"><span style="font-weight: 400;">told</span></a> <i><span style="font-weight: 400;">New Scientist</span></i><span style="font-weight: 400;">. “But we think our work does take it closer.”</span></p>
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