One Fish, Two Fish, Red Fish, Glow Fish

Danio rerio, zebrafish, are one of the most utilized model organisms to study because they have transparent embryos, have short development times, share 70% of their genetic code with humans, and are small. Major breakthroughs in therapeutics development for heart disease and cancer have been facilitated with zebrafish models, further exemplifying their power.⁷ In 1999 at the National University of Singapore, Dr. Zhiyuan Gong’s research group was studying pollutants in the water using genetically engineered zebrafish that expressed GFP signal when toxins were present.⁸ These fish were created using transgenesis, the process of adding foreign genes to the genome of an organism. In this case, the gene that encodes GFP is linked to a promoter’s DNA sequence, a sequence required for transcription of your gene of interest and ensures that your GFP protein is being expressed. This engineered DNA is then microinjected into the fish’s embryo where it will be taken up by the cell’s nucleus and incorporated into the genome. Once the zebrafish grow and the GFP signal is apart under blue light, the fish are selectively bred.⁹ This glowing fish discovery was quickly trademarked and patented by the scientists and a partnered American group from Texas to market the fish for blue light-containing aquariums and the public. GloFish became the first genetically modified pets for purchase in 2003, however where they are sold is restricted.¹⁰

These mesmerizing fish can only be sold through GloFish certified providers such as direct from the company and select retailers. However, in 2004, the company underwent a lawsuit filed by the Center for Food Safety in the United States due to the possibility of these fish becoming invasive species through the destruction of natural habitats and the worry of opening the floodgates to the possibility of unethically genetically modifying other organisms. Despite the controversy and wary pet store sellers, GloFish is still widely available in both Canada and the United States, except for California.¹¹^,¹² Additionally, while GFP was the ‘founding father’ for these glowing fish, GloFish now sells orange, pink, purple, red, and blue glowing fish.¹³

The interest and methods of creating animals that glow are not restricted to fish, in the past 25 years many labs and companies have tried to genetically engineer cats, dogs, sheep, pigs, and even monkeys to fluoresce green when in the presence of blue light.¹⁴ While it is crucial to understand the ethical ramifications of altering the genetic code of these organisms it is important to recognize how far the research field and genetics have come.