Little, Clarence Cook (1888–1971)

US pioneer of mouse genetics. He developed the first inbred mouse strains. These mouse strains are still some of the most important in use today.

Importance of mouse breeding While at Harvard University, Little realized that there was a need to develop inbred mouse strains, in which the chromosome pairs in any mouse would be identical, to allow independent workers to perform experiments on the same genetic material. The original intent of the development of these strains was to demonstrate the genetic basis for various forms of cancer.

Little began a breeding programme to produce the first inbred mouse strain 1909, while he was still an undergraduate. He called this first strain DBA because it carries mutant alleles (alternative forms of the same gene at the same position on a chromosome) at three coat-colour loci: dilute, brown, and non-agouti. The genetic basis of breast and liver cancer was demonstrated shortly afterwards when the mouse strain C3H, which has very high susceptibility to these cancers, was compared to other inbred strains.

Life Little was born in Brookline, Massachusetts, and studied at an agricultural college at Harvard University. His scientific career was interrupted by World War I, but he returned to his mouse-breeding experiments 1918 at Cold Spring Harbor 1918–22. He was appointed president of two universities (Maine and Michigan) before establishing 1929 the Jackson Memorial Laboratory in Maine, which he ran until 1956. Today, this laboratory stocks many of the inbred mouse strains that have been produced since Little's day and remains one of the best mouse-research institutes in the world.