Researchers are suggesting addition of different mouse types in laboratory tests in order to attain greater genetic diversity than is the case now. Mice and humans share about 95 percent of their genes, and mice are recognized around the world as the leading experimental model for studying human biology and disease.
The current array of laboratory mouse strains is the result of more than 100 years of selective breeding. In the early 20th century, America’s first mammalian geneticists, including Jackson Laboratory founder Clarence Cook Little, sought to understand the genetic processes that lead to cancer and other diseases. Mice were the natural experimental choice as they breed quickly and prolifically and are small and easy to keep.
Lacking the tools of molecular genetics, those early scientists started by tracking the inheritance of physical traits such as coat color. A valuable source of diverse-looking mouse populations were breeders of “fancy mice,” a popular hobby in Victorian and Edwardian England and America as well as for centuries in Asia.
Researchers can learn even more “now that we really know what a laboratory mouse is, genetically speaking, says Jackson Laboratory Professor Gary Churchill, Ph.D.
Along with Fernando Pardo-Manuel de Villena, Ph.D., of the University of North Carolina, Chapel Hill, Churchill, led an international research team to create a genome-wide, high-resolution map of most of the inbred mouse strains used today.
In their paper, Churchill and Pardo-Manuel de Villena report that “classical laboratory strains are derived from a few fancy mice with limited haplotype diversity.” In contrast, strains that were derived from wild-caught mice “represent a deep reservoir of genetic diversity,” they write.
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“As scientists use this resource to find ways to prevent and treat the genetic changes that cause cancer, heart disease, and a host of other ailments, the diversity of our lab experiments should be much easier to translate to humans,” he noted.
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The research team estimates that the standard laboratory mouse strains carry about 12 million single nucleotide polymorphisms (SNPs), single-letter variations in the A, C, G or T bases of DNA. The Collaborative Cross mice deliver a whopping 45 million SNPs, as much as four times the genetic variation in the human population. “All these variants give us a lot more handles into understanding the genome,” Churchill says.
“This work creates a remarkable foundation for understanding the genetics of the laboratory mouse, a critical model for studying human health,” said James Anderson, Ph.D., who oversees bioinformatics grants at the National Institutes of Health. “Knowledge of the ancestry of the many strains of this invaluable model vertebrate will not only inform future experimentation but will allow a retrospective analysis of the huge amounts of data already collected.”
Source-Medindia