Genetically modified dogs bred using cloned skin cells – New Scientist

A new gene-editing method could eliminate disease-causing mutations in dogs. He can even clone individual dogs.

In South Korea, two beagle dogs were bred using cloned skin cells modified with CRISPR gene-editing technology. CRISPR-treated dogs are made using modified fertilized eggs. Now, for the first time, cloned skin cells form the basis.

Many purebred dogs carry disease-causing mutations in their DNA. With the help of genetic editing, you can eliminate them without affecting other traits. Okjae Koo of biotechnology company ToolGen says DNA editing by cloning is more suitable for this than conditioning fertilized eggs. “The cloning method is more reliable in producing purebred, genetically modified dogs,” Koo says.

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cell fusion

To create the cloned pups, Ko and his colleagues first created genetically modified skin cells. They modified the DJ-1 gene in it, so that no specific protein was produced. Mutations in DJ-1 are associated with diseases such as Parkinson’s, so studying dogs that lack the associated protein could help develop treatments for these conditions.

In addition to eliminating DJ-1, the team added several genes, including genes for a green fluorescent protein called GFP. Using this protein, the researchers were easily able to tell which cells were successfully edited. Koe says the team does not plan to use these genes in future research.

The team then placed the modified skin cells next to the eggs whose DNA had been removed. The researchers then combined each skin cell with an empty egg by applying short electrical pulses. The resulting embryos were implanted into a surrogate mother.

The dogs are now 22 months old. They show no blemishes – other than their skin glowing green in ultraviolet light. Because diseases associated with DJ-1 are age-related, dogs can still develop problems as they get older.

Chimera

A total of 68 fetuses were transferred to six dogs. This resulted in two puppies – a success rate of about 3 percent. That’s a similar percentage to the study by Lai Liangxue of the Guangzhou Institute of Biomedicine and Health in China, who and his team created the first CRISPR-treated dogs — an achievement unveiled in 2015.

These dogs, called Tiangou and Hercules, are beagle dogs that have more muscle mass than normal due to the deletion of the gene. “Both Tiangu and Hercules are doing really well,” says Lai. Since then, his team has created several other dogs using the same method, he says.

Lai admits that the cloning technique used by the other South Korean team has advantages. When the fertilized eggs are genetically released, the resulting animals are usually ‘chimeras’. That is, some of their cells are genetically modified, but others are not. This means you have to keep breeding to create dogs whose cells all have the desired change, says Lai. With the cloning technique no further reproduction is required.

cloned pets

Lai and Koo’s team create medical research dogs. However, cloning is increasingly being used to make copies of beloved pets that have died, using tissue samples taken shortly after death.

In the US, a company called ViaGen has so far created about 1,000 “cloned companion animals,” a spokesperson said. new world. ViaGen charges $50,000 to clone a dog and $38,000 for a cat.

If you combine this cloning with gene editing, you can make these animals healthier. ViaGen does not currently offer any form of genetic modification, but does not rule it out in the future. “We are prepared to consider all options that are successful, that have been approved by the necessary regulatory authorities, that are good for the animals involved and that meet the needs of the community,” the spokesperson said.

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