the nickname for a bacterial mating experiment carried out at l'Institut Pasteur, Paris, that showed that induction and repression of the enzyme
β-galactosidase in
Escherichia coli are regulated by two closely linked genes, one of which produces a cytoplasmic repressing substance that blocks the expression of the other. [From the names of the experimenters: Pardee, and French molecular biologists François Jacob (1920 — ) and Jacques Monod (1910 — 76).]