Gene Editing Tool: CRISPR

Ed Yong wrote about this tech called CRISPR, which allows unprecedented levels of control on editing specific genes. The keyword is “specific”. Butterflies have become a popular choice for using CRISPR on. Why butterflies? Yong explains:

“Butterflies all evolved from a moth ancestor, so how did a presumably dull-winged insect give rise to a kaleidoscopic dynasty of some 18,000 species, each with a distinctive pattern of colors and shapes plastered on its wings? Also, what are the genes behind these patterns? How did a limited set of DNA come to produce patterns of such astonishing diversity and often-baffling complexity?”

Scientists have suspected that just a handful of pattern defining genes with names like optix, doublesex, and cortex produce most of that variety. But how could they prove it? How they wished that they could edit or delete those genes and see the effect. It would confirm or refute their theory. And now CRISPR provides them with exactly that level of precise control. By deleting the optix gene in different butterfly species, they found that the color goes away. Red to black. Orange to dark inky. Or as researcher Robert Reed says:

“They just turn grayscale (from color).”

Scientists used to be constrained to species that were easy to breed and manipulate in labs. And even then, the genes that got mixed were random. No more. With CRISPR aiming at specific genes, they found that:

“If optix is a paintbrush, then other genes act as the painter’s hands, determining where the brush will go, and yet other genes act as the paints, determining which colors the brush eventually lays down. All of this can be easily rewired, producing a wide kaleidoscope of patterns from the same basic toolkit.”

Apart from confirming (or refuting) a theory, CRISPR inevitably produces new, unexpected results. Which then opens new lines of research. An example:

“When Reed deleted optix, sure enough, the orange bits blackened. But unexpectedly, the buckeye’s wings also gained a blazing iridescence—a shiny, metallic blue.”

Where did the blue come from? When they dug in, researchers couldn’t find any blue pigments! So what was going on? The answer:

“Their iridescence is the work of microscopic layers in the wings, which collect, reflect, and amplify blue light, so that it’s especially vivid from certain angles. That’s an entirely different way of producing colors than the red and black pigments that optix typically governs.”

The way CRISPR helps close out questions and opens up new ones is transforming the field. Reed describes its effect perfectly:

“CRISPR is a miracle... the biggest challenge of my career had just turned into an undergraduate project.”x`