Animal Models: More Than Mice

While the mouse may be king, it’s not the only show in town. Beyond the mouse, several other species are used as animal models of human disease. Their usefulness might surprise you.

Discoveries made in organisms like yeast, roundworms, and zebrafish are directly applicable to human disease. These non-murine animal (and fungal) models don’t dominate fields using animals for research, but they continue to steadily serve the scientific community.¹

Bakers yeast (Saccharomyces cerevisiae) is an animal model used to study the cell cycle, and findings in yeast have translated directly to human cancer. Mutations in genes that regulate the cell cycle were first discovered in yeast, and later were realized to be the same genes that cause cancerous cells to lose control of their division.² Leland Hartwell discovered more than 100 genes involved in cell cycle regulation, and teased out the pathway that regulates cell cycle using yeast. Hartwell received the Nobel Prize in 2001 for his work. Cell cycle discoveries made in yeast could eventually lead to the development of pharmacogenomic drugs that are targeted to an individual’s specific cancer-causing mutation that affects cell division.

Roundworms (Caenorhabditis elegans) are used to study the genes and pathways involved in aging.³ They are useful as an animal model for aging studies because roundworms have a relatively short lifespan, only two to three weeks. Being so short-lived, they age relatively quickly. Experiments can move at a good clip, and be easily reproduced.

Zebrafish (Danio rerio) are often used as an animal model for drug screening. With their small size, it is possible to screen compound libraries in high-throughput tests, assaying for cytotoxicity.³ Zebrafish can also be used to screen drugs that target the vascular system, too. Their vascular development follows a reproducible pattern, so alterations to vascular development are readily apparent.

Contract research organizations (CROs) that specialize in animal models aren’t all focused on the mouse. Some specialize in alternative animal models, such as zebrafish and fruit flies, to model aspects of human disease or for drug screening. These alternative options are worth exploring, as they can be effective and less expensive than murine animal models.