For Noēma, Aryn Baker learns how to use CRISPR-Cas9 to edit the genes of zebrafish embryos. Using a microscope and a precision injection rig, she experimented with disabling a gene responsible for eye development. As she notes of the ability to play God, “The process is deceptively simple; the implications are anything but.”

I line up dozens of single-cell embryos along the edge of a glass slide. Under the microscope, they look like a string of yellowed pearls. When I prod them with an ultra-fine glass syringe, they squish like tapioca balls in a boba tea. But if I get the angle right, I can inject them with a carefully calibrated dose of CRISPR-Cas9 designed to disable a gene associated with eye development. When they hatch into larvae a few days later, they will have no eyes. If I were to allow them to reach adulthood, which I won’t, they could theoretically breed with other similarly blinded adults to create a population of eyeless fish for an aquarium exhibit of unnatural wonders.

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