A team of scientists from the Chinese Academy of Sciences, based in Beijing, has managed to produce healthy mice from two parents of the same sex, specifically two mothers. This is something that has already been achieved before; The novelty lies in the method used to achieve it, which is much more effective and safe, since they have used stem cells and specific gene editing. The 29 offspring that were born not only survived, but have also been able to procreate themselves by natural means, as reflected in the study, published in the scientific journal Cell Stem Cell .
The Chinese researchers who have carried out this work with mice have explained that they also obtained the birth of twelve offspring from two parents – they contained DNA from the two male parents and then the embryos were transferred to females who surrogate them. ; however, they did not survive beyond 48 hours.
It is not strange to find species in nature that are capable of procreating without the need to reproduce sexually. Thus, asexual reproduction has already been described in cases of zebra sharks; in fact, last year the case of Leonie was documented, a zebra shark that lives in the Australian aquarium of Reef HQ, Townsville, and that went from reproducing sexually to doing it alone in less than two years. The Komodo dragon, the largest lizard in existence, can also reproduce asexually, which is undoubtedly an evolutionary advantage.
Qi Zhou, a researcher at the Chinese Academy of Sciences, explains in a press release that they were “interested in the question of why mammals can only reproduce sexually.” “We tried to find out if we could produce normal mice born from two females, or even from two male parents, using haploid embryonic stem cells (ESCs) with gene deletions, ” he says.
A complex process
First of all, to understand the complexity of what they have achieved, it is necessary to explain that, in the case of mammals, through a genetic mechanism called imprinting, some genes of the mother or father are deactivated and are silenced during the development of gametes – male (sperm) or female (ovules) reproductive cells of a living being. If the offspring lack genetic material from one of the two parents, that offspring may suffer anomalies and defects in their development or even not be viable. So imprinting is the main problem for two subjects of the same sex to have offspring .
Years ago, Japanese scientists already achieved the birth of bimaternal mice by deleting genes imprinted from immature eggs . “However, the generated mice showed faulty characteristics and the method itself is very impractical and difficult to use,” says Zhou.
Now, these Chinese researchers have used haploid embryonic stem cells, with half the usual number of chromosomes and DNA from a single parent, in such a way that they have managed to lower the level of programmed imprinting . “We saw in this study that haploid ESCs were more similar to primordial germ cells, precursors to eggs and sperm. The genomic imprint found in gametes was erased, ”explains another of the study’s authors, Baoyang Hu.
At the moment it seems highly unlikely that, in the near future, the possibility of using similar technology in humans will be considered given the high risks that embryos could suffer from serious genetic abnormalities. Much remains to be investigated. But it is true that this study makes it clear that the biological barriers that prevent the reproduction of two subjects of the same sex may not be insurmountable .
