Rats with two fathers have their own children for the first time

For the first time, rats with two fathers continue to have themselves – marked an important step toward making two men with genetically related children. However there is another long way to go before it can try people.

Yanchang Wei In Shanghai Jiao Tong University in China reached the cause by placing two sperm cells with an egg that took the nucleus. The team immediately used a method called epigenome editing to reprogram seven sperm DNA sites, needed to develop the embryo.

In 259 of these embryos transferred to female mice, only two children – man-saved and grown in maturity. Both bore children – showing normal in terms of size, weight and appearance – after marrying women.

Making rats with two fathers proved more difficult than creating rats with two mothers. The birth of the first fertile mouse with two mothersGrief, reported in 2004.

Kaguya should change genetically, but in 2022, Wei and his colleagues have done Make the same rats without fathers using epigenome editingwithout changing the DNA order. The same method is used to make no mother mice.

The reason it is an important factor to make mammals with two fathers or two mothers because of an event called imprintingrelated to the fact that most animals have two sets of chromosomes, one inherited by the mother and one from the father.

During the formation of eggs and sperm, chemical labels have been added to these chromosomes programming some genes to be active and others may be inactive. These changes are called “epigenetic” because they do not change the agreed order of DNA, but labels can still be passed when cells can last a lifetime.

Inexpensive, the epigeetic programming of mothers is different from that of fathers, with some genes marked as “in sperm marked as” off “with eggs, and vice verly.

This means that if an egg has two sets of mother chromosomes, or two sets of fathers, it cannot be normal. A gene that needs to be active in a chromosome in a pair can turn off two, or the two copies of a gene can be active, with the one who needs “overdose” with that gene.

In case of Kaguya, researchers get it by removing the part of a gene to make the gene’s overall activity. But making rats with two fathers need many changes.

Past this year, a separate Chinese team There are some mice with two fathers to grow up to maturity After making 20 genetic changes to normalize the activity of their gene, but these rats are not completely healthy or fertile.

While correcting genetic activity by changing genetic is useful for studying lab animals, it is not acceptable because the effects of genetic changes are not fully understood.

For their epigenetic approach, Wei and his team are used modified forms of Crispr proteins commonly used for gene editing. Like standard crisprin protein, it can search specific genomes sites. But if these sequences are found, the revised proteins are added or removes the labels of the epigenetic rather than the DNA change.

The study is a primary step forward, as Helen O’Neill at the University College London. “It confirms that genomic imprinting is the main obstacle to the left of the mammals and shows it can be overcome.”

Because it does not involve the genetic change, the epigenome-editing method can be, in principle, to be used to allow similar children to have their own children themselves. However, success rate should be higher before the technique can be considered available to people. “While this research of creating children from the same sex parents promise, it is not possible to translate it from the quantity of eggs needed, the high number of women needed,” as low as success, “as Christophe Galichet In the Sainsbury Wellume Center in the UK.

There are many reasons why success rate is very low. For beginners, both sperm cells mean a quarter of embryos have two y chromosomes and should not improve. Also, epigenome editing works only on seven sites in a small proportion of embryos, and can have side effects in some cases.

The rate of success and HEALTH In animals can be improved by changing over seven sites, but it may not interpret to be used by people because sites need to vary with mice.

If young children with two fathers are often created in this way, technically they are technical be three kids kids Because the mitochondria of their cells, with a small amount of DNA, comes from donating egg.

In 2023, a Japan team announced the identity of puppies mouse with two fathers using a third approach That involves turning mouse cells into eggs. However, it cannot be clear if any puppies survived in maturity, and so far no one has managed to fight human cells with eggs.