What use is a fat mouse? Mice of all colours, shapes and sizes
were bred for fun in China and Japan in the 1600s. Victorian
Britain also had a 'mouse craze', with the foundation of the
National Mouse Club - by humans - in 1895. Breeders competed for
prizes for new varieties of fancy mice with names like 'red cream',
'ruby-eyed yellow' and 'creamy buff'. But what has this got to do
with science? The new varieties were highly desirable, and mouse
fanciers were creating masses of genetically identical mice.
Since the early 1900s scientists have used some of these mice to
investigate heredity and disease. In the 1950s, scientists
discovered a strain (a genetic variation) of unusually obese mice,
but toiled for several decades to find out why they were so fat.
Thirty years later a team led by Dr Jeffrey Friedman discovered
that the mice were lacking a particular gene. In normal animals,
this gene produced a protein called leptin that told the mouse when
to stop eating. Without leptin it kept on eating, growing fatter
and fatter. When Friedman gave the obese mice leptin they lost
weight. Was it the much longed for quick-fix for obesity? The
process turned out to be much more complex, and even now is not
fully understood.
Over the last decades, scientists have bred other strains of
mice, now standard tools of research in the hereditary aspects of
disease, from cancer to diabetes. You can even order your fat mouse
from a catalogue, just like any other piece of scientific
equipment.