[L]ast year, a team of researchers led by Alejo Menchaca at the Animal Reproduction Institue of Uruguay genetically modified some wooly ruminants to express a peptide commonly known as green fluorescent protein, or “GFP.”

GFP glows green when exposed to ultraviolet light, and was originally isolated from the jellyfish Aequorea victoria. Today, it’s used to label molecules of biomedical interest – to determine whether those molecules are being expressed, and in what quantity.

Via io9 with the full article that explains the how, why and what future implications (and uses) there are for this accomplishment.