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They went back and redesigned their Crispr system, using the updated map to keep their edits away from any essential genes. Then they tried embryos again. This time it worked. But now it was the summer of 2018; Almost three years have passed. The project was long overdue. They had to ask USDA for an extension of their grant. The long series of setbacks made Owen feel quite dejected, wishing he had never tried his luck with Crispring cattle. His recent success with editing the embryos at a new location on the X chromosome had revitalized him, but that feeling was short-lived. The first batch of edited embryos transferred to the surrogate heifer uterus did not take. From the next batch, five embryos implanted and reached the early stages of pregnancy, only to be lost a few weeks later.
Owen and Van Eenennaam consulted with breeders and vets about what they were doing wrong. They suspected that the researchers had damaged the embryos in the laboratory, perhaps during the biopsy, when they extracted a bit of the embryo to sequence it and determine if the edition had taken place. Doing so takes time and requires freezing the embryos until the results return from the sequencing lab. Each step, freezing, biopsy, editing, decreases the viability of the embryos.
There was a simpler way to do it. They could reattach that fluorescence-producing gene and shine a flash of ultraviolet light on the embryos. A green glow would tell you that the editing worked, no biopsy or freezing required. But that would make those animals transgenic; GFP comes from a species of bioluminescent jellyfish that lives in the waters of Washington state. And that would make them genetically modified organisms, or GMOs, subject to the arduous FDA approval process. The goal of the project and the use of Crispr had been to avoid that.
However, the regulatory landscape had changed as they played. In January 2017, the FDA decided to classify any edited animal DNA as a new type of drug. That meant that any exclusively male Crispr herd would be subject to the same regulation as first-generation GMOs. And if, in the eyes of the feds, moving the cows’ DNA was the same as adding a jellyfish gene, according to the team, why not make life a little easier? With little hope that livestock breeders or commercial entities were interested enough in their SRY knock-ins to bother getting tangled up with the feds, the researchers could also go ahead with the brilliant gene.
Van Eenennaam and Owen last tried, moving the SRY gene, along with the brilliant gene, to about 200 embryos. Since it was their last shot, they decided to do the editing not on the X chromosome, as they had been trying to do, but at a well-established safe harbor site on chromosome 17. Twenty-two embryos survived this process, and of those, nine shone. under ultraviolet light. But only one of them was bright green, Owen says. And a month after all the embryos had been transferred to heifers, that bright green was the only pregnancy that remained. The research team decided to name the growing calf Cosmo, after a bright green character in the animated television series Nickelodeon. Quite strange parents, which aired in the mid-2000s. “Obviously I’m too boomer, because I’ve never heard of it,” says Van Eenennaam.
The ultrasound suggested that Cosmo was a man. And when he was born on April 7, that was the second thing the vet checked after making sure his calf was breathing. “Yes, he has testicles, two of them!” he said to Van Eenennaam and Owen. “Phenotypic man, it’s a good start!”
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