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Lately in the news after United States President Donald Trump famously misstated that “USD 8 million had been spent for making mice transgender.” This was followed by House laughter and sneers from Republicans on cue, and then Trump brought up tail by claiming: “This is real.” However, the internet nearly immediately exploded to correct him: It should have been transgenic mice, not mice who plead to have their gender changed.
Etymology
But what does transgenic actually mean, then?
The root word trans means from ‘one to another’, and genetic is used in relation to genes. Transgenic refers to an organism or cell whose genome has been altered by the introduction of one or more foreign DNA sequences from another species by artificial means. Transgenic organisms are generated in the laboratory for research purposes, as per the National Human Genome Research Institute.
Fact-checkers in the U.S. reported that it might not have been a misstatement, speculating that Mr. Trump was probably referring to report from the White Coat Waste Project, a watchdog group opposing government-funded animal research, which had claimed that over $10 million had been spent on projects involving transgender mice, rats, and monkeys. This report managed to gather moss as it rolled among the conservatives, prompting the erroneous and quite homophobic charge that precious taxpayer funds were being misused in unnecessary research.
Media reports from the United States, following Trump’s remarks, stated that the White House responded by sharing a list of National Institutes of Health grants. The press release listed six studies from the database of federally-funded research projects that used mice treated with hormones and researched different aspects of gender-affirming care. This included studies on mice in the area of hormone therapy and HIV vaccine, reproductive consequences of steroid hormone administration, the impact of testosterone therapy on breast cancer, a study on how gender-affirming hormone therapy affects the microbiome, analysing androgen effects on the reproductive neuroendocrine axis and how hormones influence asthma outcomes.
The money was not spent to make mice transgendered.
Uses of transgenic mice
Transgenic animals actually include a variety of species such as fish, poultry, rabbits, pigs, sheep, goats, cattle, apart from mice. Transgenic mice have been used in genetic studies for a long time now. Linear fragments of DNA can be integrated into the genome in a random fashion. If the gene-modified chromosome enters the germline cells, it can be passed onto the progeny, which thereby contain permanently-altered genomes and are then said to be transgenic, explain Udayan Guha et al, in a chapter on transgenic mice in cancer research in the Encyclopedia of Cancer (Second Edition).
Transgenic mice, in which the gene is depleted or silenced to cause a loss of gene function, are called knockout mice. These mice provide valuable clues about the biological function of a normal gene, say Ursa Lampreht Tratar in ‘Transgenic Mouse Models in Cancer Research’ published in Frontiers Oncology.
In fact, transgenic mice were used to demonstrate that DNA is the molecule that carries the genetic code and that oncogenes can cause cancer. “Transgenic animals have been generated to understand normal physiological processes such as metabolism and blood cell production. Transgenic animals have been used to model human diseases and to develop new treatments. Transgenic crops have been produced that are resistant to infectious diseases and grow faster,” as per the National Human Genome Research Institute.
Paul P. Liu, senior investigator, Translational and Functional Genomics Branch, at the National Human Genome Research Institute, U.S., says: “With the imminent completion of the human and mouse genome sequence, it will be more feasible to identify the relevant genes underlying many fertility disorders. Already, the mouse has been utilised extensively as a genetic tool for the dissection of gene function, often providing significant insights into the relationship between gene and disease.”
In a paper published in ScienceDirect, Genetic manipulations to study reproduction, Carolina J. Jorgez et al state “to expand our understanding of fertility disorders in humans, animal models have been providing invaluable insights into reproductive physiology. The mouse has become an important animal model to study reproduction and other processes due to its physiological, anatomical, and genomic similarities with humans.” Among the advantages of using mouse as a model are: a relatively short generation time (9–10 weeks from being born to giving birth), females breed prolifically in the lab.
Insights into cancer
The paper by Ursa Lampreht Tratar et al highlights that the use of existing mouse models in cancer research is of utmost importance as they explore the casual link between candidate cancer genes and carcinogenesis, and to provide models to develop and test new therapies. The mouse as a model for human cancer research has proven to be a useful tool due to the relatively similar genomic and physiological characteristics of tumor biology between mice and humans. Mice have several similar anatomical, cellular, and molecular characteristics to humans that are known to have critical properties and functions in cancer.
Published – March 22, 2025 11:07 am IST
