The house mouse (Mus musculus) is a small rodent, a mouse, one of the most numerous species of the genus Mus. The house mouse has been domesticated as the pet or fancy mouse, and as the laboratory mouse which is one of the most important model organisms in biology and medicine. It is by far the most commonly used genetically altered laboratory mammal. Mouse and man
The sequence of the mouse genome was published in 2002. "The mouse and human genomes are very similar," says Dr Jackson. "There are a relatively small number of rearrangements, and the gene content is pretty much the same. Some gene families have expanded in the mouse, such as those involved in scent recognition, innate immunity to pathogens [humans and mice being exposed to different pathogens], and in reproduction. People have tended to comment on the differences between mice and humans, but there are so many similarities. If you find a mutation in a mouse gene, you almost always find a human disease with similar effects." Some mouse models of human disease, such as for obesity, cancer or immune system defects, have arisen spontaneously. Many other models - notably for cystic fibrosis - have been generated as knockouts. Even so, there are still thousands of diseases, and thousands of genes, that researchers have not tackled as yet. With the genome sequenced, allied to high-throughput technology, the concept of testing what every gene does, and of fully untangling how genes contribute to disease, has become a realistic goal. Laboratory mice
Mice are the most commonly used mammalian research model with hundreds of established inbred, outbred, and transgenic strains. They are common experimental animals in biology and psychology, primarily because they are mammals, are relatively easy to maintain and handle, reproduce quickly, and share a high degree of homology with humans. The mouse genome has been sequenced, and many mouse genes have human homologues. In addition to being small, relatively inexpensive, and easily maintained, several generations of mice can be observed in a relatively short period of time as mice reproduce very quickly. Most laboratory mice are hybrids of different subspecies, most commonly of Mus musculus domesticus and Mus musculus musculus. Laboratory mice can have a variety of coat colours, including agouti, black and albino. Many (but not all) laboratory strains are inbred, so as to make them genetically almost identical. The mouse in the lab
In France, Lucien Cuénot was the first - in 1902 - to demonstrate Mendelian ratios for the inheritance of coat colour characters in mice. In Harvard, William Castle began his research in the same year, buying mice from a local mouse fancier who had quickly turned her hobby into a business. Together with his student Clarence Little, Castle produced a series of seminal papers on coat-colour genetics. Little is probably best known for his development of 'lab mice' - inbred mouse strains that are still used today. "Inbred strains have been very important for mouse genetics," says Dr Jackson. "You need a uniform genetic background against which you can compare new variations. There are several hundred inbred strains, each with a different background, although only perhaps a dozen are used commonly by the research community." Little's first inbred mouse, DBA (dilute brown non-agouti), was developed in 1909; his most famous strain, C57BL/6, in 1921. C57BL/6 was the strain whose genome was sequenced and published in 2002. Clarence Little's contribution to the field was not finished. In 1929, backed by two car barons, Edsel Ford (Henry's son) and Roscoe Jackson (head of the Hudson Motorcar Company), he set up the Jackson Laboratory in Maine, USA. The lab is a world-renowned centre for mouse genetics, and has been a major influence on keeping mice at the forefront of mammalian biology. For several decades, researchers focused on finding mutants and variants, and mapping the genes...
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