​​Top 10 Genetically Modified Animals in Research

In this comprehensive overview, we delve into spontaneous vs. induced mutations in animals, highlight beneficial genetic mutations in animals that enhance survival or serve as valuable research models, and explain the role of genetic drift in animals – the random fluctuations in gene frequencies that especially affect small populations. We discuss examples of genetic mutation examples in animals such as naturally disease-resistant breeds and laboratory animal models of human conditions, and examine how genetic drift influences evolutionary biology, breeding programs, and the genetic management of lab animal colonies.

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1. Oncomouse – A Pioneering Genetically Modified Mice for Cancer Research

The Oncomouse, one of the earliest genetically modified animal models, was engineered to carry an activated oncogene that predisposes it to develop various types of tumors, particularly mammary tumors. This was achieved by inserting the v-Ha-ras oncogene under the control of a mouse mammary tumor virus promoter. The Oncomouse has since become a foundational model in cancer biology, enabling researchers to study tumor initiation, progression, and metastasis in a whole-organism context. This model facilitates high-throughput screening of anti-cancer drugs, investigation of tumor suppressor genes, and exploration of genetic and environmental interactions in oncogenesis. Its reproducible and well-characterized tumor development has made it indispensable for preclinical cancer research.

2. GloFish (Fluorescent Zebrafish) – Bright Bioindicators and GMO Pets

GloFish are genetically engineered zebrafish that express fluorescent proteins originally derived from marine organisms, such as jellyfish and coral. These proteins include green, red, and orange fluorescent markers, which are stably expressed throughout the fish's tissues and inherited by offspring. While their commercial popularity as ornamental pets is well known, GloFish have significant scientific value. They are widely used as bioindicators for environmental toxins and to study developmental biology, thanks to their transparent embryos and visible gene expression. In research, fluorescent GloFish allow real-time tracking of cell migration, organogenesis, and the effects of genetic mutations. These traits make them a vital tool for in vivo imaging and toxicity screening.

3. AquAdvantage Salmon – Fast-Growing GM Fish for Food Security

AquAdvantage salmon have been genetically modified to grow significantly faster than wild-type Atlantic salmon. This is accomplished by integrating a growth hormone gene from Chinook salmon under the control of a regulatory promoter derived from ocean pout, enabling year-round expression. As a result, AquAdvantage salmon reach market size in approximately half the time. In research, they serve as a robust model for studying metabolic pathways, nutrient assimilation, and gene regulation associated with accelerated growth. Their development has also prompted investigations into resource efficiency in aquaculture, genetic stability across generations, and strategies for enhancing animal productivity through transgenesis. These fish exemplify the application of genetic engineering to improve agricultural yield.

4. Oxitec Mosquitoes – Genetically Modified Insects Fighting Disease

Oxitec mosquitoes are genetically modified Aedes aegypti mosquitoes designed to reduce mosquito populations through a self-limiting gene. Male mosquitoes are engineered to carry a gene that disrupts development in offspring, causing them to die before reaching maturity. These mosquitoes have revolutionized research in vector control and population genetics. They provide valuable insights into insect population suppression strategies, gene drive technologies, and species-specific pest management. In laboratory and semi-field settings, scientists use them to examine mating behavior, inheritance patterns of engineered traits, and ecological modeling of mosquito-borne disease dynamics. Their utility has expanded research on genetic containment and precision biocontrol methods.

5. ATryn Goats – Transgenic Goats Producing Life-Saving Medicine in Milk

ATryn goats are transgenic animals engineered to express the human antithrombin gene in their mammary glands, resulting in secretion of the anticoagulant protein in milk. This genetic modification allows for large-scale, cost-effective production of recombinant antithrombin, which plays a critical role in preventing abnormal blood clotting. From a research perspective, these goats serve as a model for mammalian bioreactors and enable studies on transgene expression control, protein folding, and post-translational modifications in milk. They have paved the way for the development of other livestock-based pharmaceutical production platforms and are essential for advancing biomanufacturing techniques using genetically engineered large animals.

6. Enviropig – A GMO Pig for Environmental Sustainability

Enviropigs are genetically modified Yorkshire pigs that express the enzyme phytase in their salivary glands, enabling them to break down phytic acid in grains and absorb dietary phosphorus more efficiently. This modification significantly reduces phosphorus content in manure, mitigating agricultural runoff and eutrophication. In research, Enviropigs are used to study nutrient metabolism, digestive enzyme function, and sustainable livestock practices. They also serve as a model for evaluating gene integration stability, promoter activity in specific tissues, and long-term effects of transgene expression on animal health and productivity. Their development highlights the environmental applications of genetic engineering in agricultural species.

7. Hornless Cattle – Gene-Edited Cows for Humane Farming

Hornless cattle have been gene-edited to carry the polled (hornless) trait naturally found in certain beef breeds, such as Angus, but absent in high-yield dairy breeds like Holstein. Using targeted genome editing techniques, such as TALENs or CRISPR /Cas9, scientists inserted the polled gene without introducing foreign DNA. These animals retain all desirable dairy traits while eliminating the need for painful dehorning procedures. In addition to improving animal welfare, hornless cattle offer a research model for precision breeding, allele-specific gene replacement, and heritability studies. They exemplify the potential of genome editing to rapidly introduce beneficial traits into elite livestock lines without compromising performance.

8. Avian Flu–Resistant Chickens – Poultry Protected by Genetic Modification

Avian flu–resistant chickens have been genetically engineered to express an artificial RNA decoy that interferes with the replication machinery of avian influenza viruses. This decoy targets the viral polymerase, reducing the likelihood of successful viral propagation and transmission. These chickens serve as important models for studying host-pathogen interactions, genetic resistance mechanisms, and molecular barriers to viral replication. Researchers use them to investigate innate immune responses, viral evolution under selection pressure, and the feasibility of engineering disease-resistant livestock. The modification represents a novel strategy for controlling infectious diseases in poultry populations through endogenous genetic mechanisms.

9. Transgenic Monkeys – GM Primate Models for Human Disease Research

Transgenic monkeys have been engineered to express human disease genes associated with neurological and psychiatric disorders, such as MECP2 for autism spectrum disorders or HTT for Huntington's disease. These primates exhibit behavioral phenotypes and neuropathological changes closely resembling human conditions, providing a unique platform for neuroscience research. They are used to explore gene expression patterns in the brain, developmental timing of disease onset, and preclinical evaluation of potential interventions. The use of transgenic monkeys bridges the gap between rodent models and human clinical studies, offering unparalleled insights into complex cognitive and neurodegenerative disorders.

10. Transgenic Fruit Flies – Tiny Models with a Big Impact on Human Genetics

Transgenic fruit flies (Drosophila melanogaster) are extensively used in genetics and developmental biology due to their short lifecycle, ease of genetic manipulation, and conservation of many human disease genes. Modifications include insertion of reporter genes, inducible gene expression systems, and homologs of human disease-associated genes. These flies are instrumental in dissecting gene function, studying pathways in neurodegeneration, metabolism, and cancer, and conducting high-throughput genetic screens. They also support research in circadian rhythms, synaptic development, and age-related decline. Their genetic tractability makes them indispensable for elucidating the molecular basis of complex traits and diseases.

Biosafety and Regulatory Considerations for GMO Animals

While genetically modified animals have transformed research, their use is closely regulated to ensure safety and ethical standards. Laboratory-contained models, such as mice, flies, and primates, operate under stringent oversight by institutional biosafety and animal ethics committees. Research animals are not released into the wild and are subject to strict breeding control. For food and agricultural applications, regulatory agencies assess safety, environmental impact, and genetic stability before approval. The acceptance and regulation of GM animals vary by region, with some countries adopting progressive frameworks and others maintaining cautious or restrictive policies. Continuous dialogue among scientists, regulators, and the public is essential to navigate ethical considerations and maximize the benefits of genetic engineering.

BioVenic is committed to supporting responsible innovation in animal biotechnology, providing researchers with advanced models and other transgenic animals-related services that meet the highest standards of scientific excellence and biosafety. Our services include but are not limited to:

• Animal Genome Modification Validation
• Transgenesis in Precision Animal Breeding
• CRISPR Genome Editing in Precision Animal Breeding
• CRISPR gRNA Services in Precision Animal Breeding
• Custom CRISPR Libraries in Precision Animal Breeding
• Precision Swine Breeding
• Precision Bovine Breeding
• Precision Sheep Breeding
• Precision Goat Breeding
• Precision Chicken Breeding
• Precision Fish Breeding

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References

1. Choe, Chong Pyo, et al. "Transgenic fluorescent zebrafish lines that have revolutionized biomedical research." Laboratory Animal Research 37 (2021): 1-29. https://doi.org/10.1186/s42826-021-00103-2
2. Cai, Dan-Chao, et al. "MECP2 duplication causes aberrant GABA pathways, circuits and behaviors in transgenic monkeys: neural mappings to patients with autism." Journal of Neuroscience 40.19 (2020): 3799-3814. https://doi.org/10.1523/JNEUROSCI.2727-19.2020
3. Looi, Fong Yang, et al. "Creating disease resistant chickens: a viable solution to avian influenza?." Viruses 10.10 (2018): 561. https://doi.org/10.3390/v10100561
4. Young, Amy E., et al. "Genomic and phenotypic analyses of six offspring of a genome-edited hornless bull." Nature biotechnology 38.2 (2020): 225-232. https://doi.org/10.1038/s41587-019-0266-0
5. Van Eenennaam, Alison L., et al. "Genetic engineering of livestock: the opportunity cost of regulatory delay." Annual Review of Animal Biosciences 9.1 (2021): 453-478. https://doi.org/10.1146/annurev-animal-061220-023052