Some mice were born without needing a biological father. What revolutionize medically assisted procreation.
By removing key DNA sequences from embryonic stem cells taken from female mice, Chinese researchers have succeeded in launching a new generation of small mammals without the males needing to fertilize eggs.
These fatherless mice not only became adulthood, but also had their own babies, demonstrating that the method is a significant improvement over previous attempts to assist reproduction without the need for a parent. male and female.
Reproduction without spermatozoa
Biologists at the Chinese Academy of Sciences have used a special selection technique on haploid embryonic stem cells (ESCs) of male and female origin. These are cells that contain only half the chromosomes of a species.
Sperm-free reproduction - a process called parthenogenesis - is nothing new in the animal kingdom. Many insects can get clones out of their mothers. The same goes for a number of fish. There are even lizards and amphibians without dad.
"Why mammals can only be sexually reproduced?" We asked the question, "said Qi Zhou, co-director of the study. "In mammals, the genes vary depending on whether the cells are from the mother or father.This genomic imprinting process means that the combination of a half-dose of genetic material from only two eggs or two sperms is likely to cause to silence both copies of an essential gene, which we absolutely did not want in the case of single-sex parents, "she says.
In 2004, Japanese researchers were able to overcome this obstacle by selecting a set of maternal chromosomes that contained the least amount of DNA fingerprinting. This sperm analogue was then used to fertilize a typical oocyte by making a mouse with two mothers.
The process is still far from perfect. Of the 210 embryos so produced, only 29 live mice were born. "If the research is reproducible and works well in humans, you still have to demonstrate its safety," said Bob Williamson, Chairman of Stem Cells Australia. In any case, it opens up interesting paths for medically assisted procreation.