Three Green Mice!

Science World, Feb 8, 1999 by Mark Bregman

You're not imagining it-these baby mice glow green in the dark! Or at least they do when they're exposed to ultraviolet (high-frequency) light. Researchers at Osaka University in Japan injected mouse embryos (fertilized eggs) with a gene found in North American jellyfish. The gene, the basic unit of heredity, contains the code for green fluorescent protein--the substance that causes jellyfish to emit light.

Born last June, the mice were part of a research experiment. "But this isn't what we expected!" says biologist Masaru Okabe. The scientist was trying to find a way to label specific animal cells. In this case, he hoped to label and track the development of mouse sperm. But what popped out from mom were mice whose every cell--except sperm, red blood cells, and hair-glow fluorescent green in the dark.

Well, at least mom will always be able to keep track of the kids.