Gene-edited livestock ‘surrogate cirrus’ successfully made fertile

A gene-aided surrogate bull. Sincerely: Bob Hubner, Washington State University

For the first time, scientists have created pigs, goats, and cattle that can serve as viable “surrogate cirrus”, which are male animals that only produce sperm carrying the genetic traits of donor animals.

In advance, published in Proceedings of the National Academy of Science On 14 September, could accelerate the spread of desirable characteristics in livestock and improve food production for a growing global population. This enables breeders in remote areas to have better access to the genetic material of elite animals from other parts of the world and allows more precise reproduction in animals such as goats where artificial insemination is difficult to use.

Reproductive biologist John Otley of the WSU College of Veterinary Medicine said, “With this technology we can better disseminate desirable traits and improve the efficiency of food production. It has a major impact on addressing food insecurity worldwide Can put. ” “If we can deal with this genetically, it means that we have to put less water, less feed and less antibiotics into animals.”

A research team led by Otley used the gene editing tool, CRISPR-Cas9, to exclude genes specific for male reproduction in male embryos that would be picked up to become surrogate cirrus. Male animals were then born sterile but researchers began to produce sperm after transplanting stem cells from donor animals in their tests. The production of sperm surrogate held only the genetic material of selected donor animals. The gene-editing process employed in this study seeks to bring about changes within an animal species that may occur naturally, such as infertility.

WSU is the result of six years of collaborative work between researchers at Utah State University, the University of Maryland and the Roslin Institute at the University of Edinburgh in the UK.

Researchers used CRISPR-Cas9 to produce mice, pigs, goats and cattle that lacked a gene called NANOS2 that is specific to male fertility. Male animals became sterile, but otherwise healthy, so when they found sperm-producing stem cells from other animals, they started producing sperm derived from donor cells.

Surrogate saints were confirmed to have active donor sperm. Surrogate mice gave birth to healthy offspring that carried forward the genes of donor mice. Large animals have not yet been banned. Otley’s lab is refining the stem cell transplant process before taking that next step.

The study provides a powerful proof of concept, Professor Bruce Whitelaw of the Roslin Institute said.

“It shows the world that this technology is real. It can be used,” Whitelaw said. “Now we have to go in and use it in the best way possible to help feed our growing population.”

Gene-edited livestock 'surrogate cirrus' successfully made fertile

Reproductive biologist John Otley of Washington State University fed a “goat head” to a goat. Sincerely: Bob Hubner, Washington State University

Latest step in animal husbandry

Scientists have been finding a way to create surrogate cirrus for decades to overcome the limitations of selective breeding and artificial insemination, devices that require either close proximity to animals or strict control of their movement – and in many cases, Both.

Artificial insemination is common in dairy cattle that are often limited so their reproductive behavior is relatively easy to control, but this process is rarely used with beef cattle that need to roam freely to feed is. For pigs, the process still requires animals because pig sperm do not survive the cold well. In goats, artificial insemination is quite challenging and requires surgical procedure.

Surrogate ser technology can solve those problems because surrogate donors distribute genetic material in a natural way – through normal reproduction. This enables ranchers and herds to allow their animals to negotiate range or territory in general. The donor and the surrogate do not need to be close to each other because either the frozen donor sperm or the surrogate animals can send themselves to different places. In addition, female NANOS2 knockout animals remain infertile – since the gene only affects male fertility – and can be bred to efficiently produce sterile males to be used as surrogate saints.

The technique has great potential to help the food supply to places in the developing world, where Irina Polojeva, a professor at Utah State University, said herds still have to rely on selective breeding to improve their stock .

“Goats are the number one source of protein in developing countries,” Poljeva said. “This technique may allow rapid spread of specific symptoms in goats, whether it is disease resistance, greater heat tolerance or better meat quality.”

Surrogate cirrus technology may also open up a new option for genetic conservation of endangered species, whose declining numbers leave animal communities isolated from each other, limiting their genetic diversity.

Perception and policy are hindered

None of the benefits of surrogate saints can be realized, however, without changes in government regulations and the current landscape of public perception.

Even when the technology is advanced enough for commercialization, gene-edited surrogate cirrus cannot be used in the food chain anywhere in the world under current regulations, even though their offspring will not be gene-edited. This is due to misconceptions that gene editing is similar to controversial gene manipulation, Ottley said. Gene editing involves making changes within a species that can occur naturally. It does not combine DNA of different species.

Otley realizes there is a lot of work to do outside the lab and recently joined the National Task Force on Gene Editing for Researchers to bring together researchers, industry representatives, bioethics and policy makers. Could.

“Even if all science is eliminated, the speed with which action can be taken in livestock production anywhere in the world is going to be influenced by social acceptance and federal policy,” Ottley said. “By working with policy makers and the public, we can help assure the public that this science does not take the risks that other methods do.”

Pig gene advances may boost sperm stock from prized animals

more information:
Michella Ciscarelli L. al., “Donor-derived spermatogenesis after stem cell transplantation in sterile NANOS2 knockout men.” PNAS (2020).

Provided by Washington State University

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