The Van Trump Report

CRISPR Scientists Create “Surrogate Sires”

Jon Oatley, director of WSU’s Center for Reproductive Biology, feeds a surrogate goat at the campus of Washington State University, in Pullman, U.S., August 7, 2020. Bob Hubner/Washington State University via Reuters

CRISPR scientists continue to find new applications for the gene-editing technology in agriculture. One of the latest breakthroughs that could completely transform precision breeding is the use of “surrogate sires” — male animals that produce sperm carrying only the genetic traits of donor males. The researchers behind the project say the advance could speed the spread of desirable characteristics in livestock and improve global food production.

The team of U.S. and U.K. researchers used CRISPR-Cas9 gene-editing technology to create pigs, goats, and cattle that can serve as viable ‘surrogate sires,’ male animals that produce sperm carrying only the genetic traits of donor animals. The male animals were effectively born sterile, but otherwise healthy, and began producing sperm after researchers transplanted stem cells from donor animals into their testes. The surrogate sires were confirmed to have active donor sperm. The surrogate mice fathered healthy offspring who carried the genes of the donor mice. The larger animals have not been bred yet as the researchers are refining the stem cell transplantation process before taking that next step.

“With this technology, we can get better dissemination of desirable traits and improve the efficiency of food production. This can have a major impact on addressing food insecurity around the world,” said Jon Oatley, a reproductive biologist with WSU’s College of Veterinary Medicine. “If we can tackle this genetically, then that means less water, less feed, and fewer antibiotics we have to put into the animals.”
Traditional methods like selective breeding and artificial insemination require either animal proximity or strict control of their movement, and in many cases, both. While artificial insemination is commonly used in dairy cattle—which are often confined and so their reproductive behavior is relatively easy to control—the procedure is rarely used with beef cattle that need to roam freely to feed. And for pigs, the procedure still requires the animals to be nearby, as pig sperm does not survive freezing well. In goats, artificial insemination is quite challenging and could require a surgical procedure. Surrogate sire technology could solve those problems since the surrogates deliver the donor genetic material the natural way — through normal reproduction.

The reported achievements are the result of six years of collaborative work by researchers at Washington State University, Utah State University, University of Maryland, and the Roslin Institute at the University of Edinburgh in the U.K. Simon Lillico, PhD, research fellow at the Roslin Institute and author of a paper about the work notes that genetic improvements to livestock in advanced breeding technologies have been hugely successful in advanced economies. “This development has potential application for genetic improvement of livestock in low- and middle-income countries,” he says.

The technology is still years from being ready for the real world and commercialization of the method is dependent on a number of things, one of the biggest being government regulation. Gene-edited surrogate sires could not be used in the food chain anywhere in the world under current regulations, even though their offspring would not be gene-edited.  The study, available HERE, was supported by the USDA National Institute of Food and Agriculture, WSU’s Functional Genomics Initiative. (Sources: Science Daily, GenEngNews, Genetic Literacy Project)

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