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Scientists have used gene editing to create pigs, goats and cattle that can serve as “surrogate bulls” – male animals that provide sperm bearing the genetic traits of elite donor animals – in an attempt to address global food insecurity. .
For thousands of years, farmers have selectively bred livestock to defend superior traits such as disease resistance and heat tolerance, but techniques such as artificial insemination are often limited by technical and logistical challenges.
But by using the Crispr-Cas9 gene editing tool, often compared to a pair of molecular scissors, to remove a gene that is specific to male sterility, the hope is that farmers can use a more efficient approach to address the growing challenges of world food. insecurity, climate change and species in danger of extinction.
The scientists created sterile but otherwise healthy mice, pigs, goats and cattle. The animals were then transplanted with donor sperm-producing stem cells, resulting in the production of donor sperm.
So far, surrogate mice have sired healthy offspring with genes from donor mice, providing key proof of concept for the technique. But it’s early days for researchers, who are still fine-tuning the process for larger animals and hope to generate that data in the coming years.
This process ensures that the surrogate parent is not producing a gene-edited product, because the result comes from a donor whose genetic code has not been tampered with, noted study author Jon Oatley of Washington State University.
“The surrogate father, although genetically edited … is serving as a container to produce an animal that would then come in and provide products for human consumption.”
This is a departure from controversial genetically modified (GM) organisms, which involve the transfer of entire genes or groups of genes from one species to another. However, gene editing is a form of genetic engineering that modifies a living genome by removing, modifying, or replacing DNA.
“Sometimes … it is not appreciated that we have been handling animals for probably 10,000 years, since the domestication of livestock,” Oatley said.
“They were combining genetic material through forced reproduction, and therefore designing a genome that may not have developed through normal natural selection alone … we are just doing it in a more precise and efficient way.”
The potential for off-target effects, whereby a proverbial cut in one area could affect another part of the genome, is a risk that is being closely examined, the researchers said.
Meanwhile, Crispr has had some success in the livestock industry making animals resistant to timely pathogens – for example, researchers at the University of Edinburgh have created pigs that appear to be immune to a virus that costs the swine industry thousands of millions every year.
The main impediment to the widespread adoption of gene editing technology is government regulation. In the EU, for example, plant and animal gene editing is governed by the strict laws governing transgenic organisms (GMOs). But the technology can easily be incorporated into production in loosely regulated South American countries, such as Argentina and Brazil, the researchers said.
The technology is unlikely to be commercialized if it is regulated as a GMO, said Dr. Alison Van Eenennaam of the University of California, Davis, who was not involved in the study.
These researchers have a long way to go to show that the technology works in real cattle, but public perception, which plays a role in shaping regulation, will likely be influenced by activist groups that have historically mounted intense opposition, emphasized.
“All it does is slow down the rate of genetic improvement, which has a negative impact on the overall sustainability of agriculture.”
Professor Bruce Whitelaw, another author of the surrogate father study, took a more optimistic tone, suggesting that social attitudes were changing.
“I wouldn’t go so far as to say that there is general acceptance around gene editing technology, but there is certainly a shift in understanding that this technology can contribute.”
