08/07/2020 First males that can reproduce with sperm from donor animals.
Scientists have genetically edited the first animals capable of being viable surrogate males: they produce sperm that carry only the genetic traits of donor animals.
RESEARCH AND TECHNOLOGY POLICYWASHINGTON STATE UNIVERSITY / ROBERT HUBNER
MADRID, 15 (EUROPA PRESS)
Scientists have genetically edited the first animals capable of being viable surrogate males: they produce sperm that carry only the genetic traits of donor animals.
This groundbreaking research, published in the Proceedings of the National Academy of Sciences on September 14, could accelerate the spread of desirable traits in livestock and improve food production for a growing world population.
It would also allow breeders in remote regions better access to genetic material from elite animals from other parts of the world and allow for more accurate reproduction in animals such as goats, where artificial insemination is difficult to use.
With this technology, we can achieve better dissemination of desirable traits and improve the efficiency of food production. This can have a major impact in addressing food insecurity worldwide, Jon Oatley, a reproductive biologist, said in a statement. from the College of Veterinary Medicine at Washington State University. If we can address this genetically, then that means less water, less food, and fewer antibiotics that we have to put into the animals.
A research team led by Oatley used the gene-editing tool, CRISPR-Cas9, to remove a specific male fertility gene in animal embryos that would be bred to become surrogate bulls. The males were born sterile, but began producing sperm after researchers transplanted stem cells from donor animals into their testes.
The sperm produced by the surrogate males contained only the genetic material of the selected donor animals. The gene-editing process used in this study seeks to provoke changes within an animal species that could occur naturally, such as infertility.
SIX YEARS OF WORK RESULT IN SUCCESS WITH MICE
The study is the result of six years of collaborative work between researchers from WSU, Utah State University, the University of Maryland and the Roslin Institute at the University of Edinburgh in the United Kingdom.
The researchers used CRISPR-Cas9 genetic scissors to produce mice, pigs, goats and cattle that lacked a gene called NANOS2 that is specific for male fertility. The males grew sterile but otherwise healthy, so when they received transplants of sperm-producing stem cells from other animals, they began to produce sperm derived from donor cells.
The surrogate males were confirmed to have active donor sperm. The mice sired healthy offspring that carried the genes of the donor mice. The largest animals have not yet been bred. Oatleys lab is perfecting the stem cell transplant process before taking the next step.
This study provides a powerful proof of concept, said Professor Bruce Whitelaw of the Roslin Institute. This shows the world that this technology is real. It can be used, Whitelaw said. Now we have to go and find out what is the best way to use it productively to help feed our growing population.
Scientists have been searching for a way to create surrogate males for decades to overcome the limitations of selective breeding and artificial insemination, tools that require close proximity of animals or tight control of their movement, and in many cases, both.
Artificial insemination is common in dairy cattle that are often confined, so their reproductive behavior is relatively easy to control, but the procedure is rarely used with beef cattle that need to roam freely to feed. For pigs, the procedure still requires animals to be close by as pig sperm does not survive freezing well. In goats, artificial insemination is quite challenging and may require a surgical procedure.
Surrogate parent technology could solve those problems, as surrogates deliver donor genetic material naturally, through normal reproduction. This allows ranchers and herders to allow their animals to interact normally in the field.
Donors and surrogates do not need to be close to each other, as the donors frozen sperm or the surrogate animal itself can be shipped to different locations. Furthermore, females knocked out by NANOS2 remain fertile, as the gene only affects male fertility, and could be bred to efficiently generate sterile males for use as surrogate males.
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