Gene editing can change an animal’s sex.
A graduate student was waiting for Alison Van Eenennaam in the doorway of her lab at the University of California, Davis. An Australian geneticist, she spends days on the road arguing with critics of Monsanto’s GM soybeans, appearing in documentaries, and telling the public why genetic modification is safe.
Her scientific work, though, involves cattle. Now, as the student, Joey Owen, whispered something in her ear, she let out a hearty “Yeaaaah” in her Down Under drawl. “We have knock-in!”
After a year of trying, the lab had just used the gene-editing tool CRISPR to add a gene called SRY to some bovine skin cells. And SRY is no ordinary bit of DNA. All on its own, the presence of SRY can make a female turn out to be essentially male—with bigger muscles, a penis, and testicles (although unable to make sperm).
“This is not a normal day in the lab,” Van Eenennaam said.
Gene-editing technology has big potential in farm animals. It has been used to create pigs immune to...