For example, cats injected with the glow-in-the-dark gene are more resistant to feline HIV, which affects 500 million cats around the world. Scientists have also injected fish with glow-in-the-dark genes in order to track their migration. If you couldn’t care less about cats or the environment (what kind of monster are you?), then perhaps knowing that scientists are also using glow-in-the-dark animals to learn more about debilitating diseases, such as Parkinson’s and Alzheimer’s, will change your mind.