Latest news with #KatsuhikoHayashi
Yahoo
25-03-2025
- Science
- Yahoo
This Mouse Has Two Biological Dads?!
In a lab in Japan, scientists transformed cells from the tails of male mice into eggs. They fertilized the eggs with ordinary mouse sperm and implanted them in surrogate mouse moms. The experiment was repeated 630 times. Although most of the pregnancies failed, seven healthy mice were born. Each of those seven baby mice had two biological dads. The experiment has staggering implications for the future of human reproduction. Biologist Katsuhiko Hayashi, who led the project, predicts that within a decade, a human skin cell could be used to create a viable human egg. The biotech companies Conception Bio and Gameto are already working on this technology. This would allow same-sex couples to have natural offspring. Perhaps even solo reproduction will be possible, with one man generating both the sperm and the egg. Some conservatives are alarmed. "The global fertility industry seeks to erase women from procreation one manufactured egg at a time," Jordan Boyd wrote at The Federalist. Actually, this technology would be empowering for women who want to have children but can't produce viable eggs—or for older women who have already gone through menopause. Younger women would also benefit. If a piece of skin can be turned into a viable egg, women doing IVF will be saved from daily hormone injections and from needles in their vaginas, both of which are part of the standard retrieval process today. Ben Hurlbut, a bioethicist at Arizona State University, told USA Today that this technology is "a perversion of the sanctity of procreation as a fundamental aspect of human life." It's not a perversion of anything. Procreation is a fundamental aspect of human life—and with this technology, more people would be able to take part. Just ask the 9 percent of men and 11 percent of women of reproductive age in the United States who have experienced fertility problems. Marcy Darnovsky, head of the left-wing Center for Genetics and Society, warned on NPR that this technology could have dystopian consequences, noting that "this could take us into kind of a Gattaca world." Darnovsky was referencing the 1997 sci-fi movie in which a eugenicist state is ruled by people born with genetically enhanced abilities. It's true that this technology could allow parents to test their embryos before implantation and select the traits of their future offspring. But IVF already makes this possible. Today, parents routinely test embryos for heritable conditions and for gender. In the future, they may be able to select for more qualities. And there's nothing wrong with that. As Stanford University bioethicist Hank Greely correctly observes, we should rely on "parental choices to make decisions about how people wish to create families." This follows from the reasonable presumption that parents generally seek to provide the best lives for their kids. The sorry history of eugenics in the U.S., where tens of thousands were forcibly sterilized during the 20th century, should make anyone cautious about government meddling in people's reproductive choices. The ability to turn mouse tails into mouse babies could become the latest technology to give humans more freedom to have the lives they choose with the families of their dreams. This video is based on the essay "What if Men Could Produce Their Own Eggs?," from our February 2024 issue. Photo credits: K. Hardy (CC BY 4.0), National Institute of Arthritis and Musculoskeletal and Skin Diseases NIH (CC BY-NC-SA 2.0), Atdoan0 (CC BY-SA 4.0), Internet Archive Book Images (CC0 1.0), Bada Bing (CC BY-NC-SA 2.0), Peter Hermes Furian, Zurijeta, 7active Studio, Srckomkrit Music credits: "Movements," by Skygaze. Licensed by Artlist. Graphics Producer: Lex Villena Narration: Katherine Mangu-Ward The post This Mouse Has Two Biological Dads?! appeared first on
Yahoo
05-02-2025
- Science
- Yahoo
How to reproduce with two fathers – and no biological mother
At the Third International Summit on Human Genome Editing, held in March 2023 at the Francis Crick Institute in London, Japanese researcher Katsuhiko Hayashi stunned attendees when he explained how he had successfully reproduced mice from two male parents. In effect, Hayashi had developed a complex procedure for turning male pluripotent (meaning embryonic or inducible) stem cells into female stem cells, allowing him to obtain eggs from a male. His surprising findings were published in the journal Nature a few weeks later. Almost two years later, a team of Chinese researchers – led by Zhi-kun Li, Wei Li and Qi Zhou of the Chinese Academy of Sciences – has once again shocked the field of genetics with a similar procedure. However, these scientists found a completely different way of achieving the same result. They produced a baby mouse from two males without maternal biological intervention, beyond needing a female mouse to gestate the embryos generated. Their results were published last month in the journal Cell Stem Cell. This new procedure developed by Li and colleagues combats a mammalian control system called genetic imprinting, which prevents viable mammal embryos from being obtained by combining two gametes of the same sex (two sperm or two eggs). These embryos do not survive naturally, since in mammals every embryo has to derive from a male gamete (sperm) and a female gamete (egg). The reason for this is that some genes are only expressed if they are inherited from the mother, while others have to be inherited from the father. And all of them are essential for survival. The Chinese researchers' highly complex process manages to convert, after numerous steps, a spermatozoa into a cell that behaves like an egg cell. They did this by deactivating the imprinting barrier, which is found at twenty points in the genome, through gene editing with CRISPR tools. This cell (now with the genetic characteristics of an egg) can be combined with another spermatozoa to create a viable mouse embryo. That embryo is gestated by a mouse, and the mice that are born are derived from two sperm, from two fathers, without the genetic involvement of eggs, or a mother. This process is still not without problems. As the study's authors acknowledge, the mice created by this process are not fertile, and can only be reproduced through cloning. Additionally, more than half of the mice born to two fathers either do not survive, die young, fail to mature properly, or fail to reach adulthood. In a previous study from 2018, the same research team had shown that mice born to two mothers were fertile and survived longer than those born to two fathers, all of whom died shortly after birth. In their new study, published last month, the results have improved, though only partially. Though these experimental studies were conducted on mice, they raise the question of whether such procedures could ever safely produce human embryos, and what impact this would have. This is not yet possible, though if it were, it would revolutionise fertility treatments. Male same-sex couples, for instance, could both be the biological parents of their children – one would provide sperm and the other would provide pluripotent stem cells which, following either of the two procedures (that of the Japanese or the Chinese researchers), would produce eggs that could be fertilised in vitro and gestated by a woman through surrogacy. Surrogacy is illegal across much of the EU, but permitted in other countries. Similarly, a female same-sex couple could also have biological children, where one contributes eggs and the other pluripotent stem cells that end up producing sperm. Either of the two women could gestate the resulting embryo, and the children born would be the biological children of both mothers. For the moment, these human applications remain in the realm of science fiction – they are not yet technically possible, and it would be unwise to try to implement them. However, assuming that all these processes will be optimised to the point where we can consider offering them in fertility clinics, I believe it is important to reflect on this. We must ask ourselves, as a society, whether we would be willing to ethically and legally accept these techniques. A version of this article was originally published in Science Media Centre España. Este artículo fue publicado originalmente en The Conversation, un sitio de noticias sin fines de lucro dedicado a compartir ideas de expertos académicos. Lee mas: Geneticists have finally solved the mystery of Garfield's orange coat Why more twins are being born than ever before – even though birthrates are falling How (apparently) identical animals can have different genomes – new research The contents of this publication and the opinions expressed are exclusively those of the author and this document should not be considered to represent an official position of the CSIC nor does it commit the CSIC to any responsibility of any kind.
