Scientists engineered a glowing cuttlefish. Why was it so hard? | Science

Editor’s note: This article references a preprint that Carrie Albertin, an MBL adjunct scientist and Aalok Varma, a MBL Whitman Fellow are coauthors on. It also features insights on the work from Joshua Rosenthal, a senior scientist at the MBL.

When Tessa Montague learned about CRISPR, the gene-editing system that was supposed to make it easy to modify any organism, she set her sights on the cuttlefish. The Columbia University neuroscientist dreamed of injecting its embryos with genes that would prompt its neurons to fluoresce as they fired. The flashes would let her track how this tentacled creature’s brain controls one of its most striking behaviors: camouflaging itself by copying patterns it perceives in its surroundings onto its skin. Unlike most animals, she says, “cuttlefish can actually tell us what they see.”

But it was not easy at all. Injecting gene-editing tools into a fertilized egg required peeling away dozens of layers of jelly, developing pincers that squeeze the egg with a precise amount of force, designing a needle with the right angle to pierce its nearly invisible lens-shaped embryo, and keeping the delicate baby cuttlefish alive once they hatch. “Sometimes I think we’ve experienced every type of failure possible,” Montague says.