Lwoff, André Michael (1902-)

French microbiologist who proved that enzymes produced by some genes regulate the functions of other genes. He shared the 1965 Nobel Prize for Physiology or Medicine with his fellow researchers Jacques Lucien Monod and François Jacob. Lwoff was born in Ainy-le-Château, Allier. From 1921 he worked at the Pasteur Institute. During World War II he was active in the French Resistance. He was professor at the Sorbonne 1959-68 and head of the Cancer Research Institute in Villejuif 1968-72. In the 1920s, Lwoff demonstrated the coenzyme nature of vitamins. He also discovered the extranuclear genetic control of some characteristics of protozoa. In the late 1940s, Lwoff worked out the mechanism of lysogeny in bacteria, in which the DNA of a virus becomes attached to the chromosome (DNA) of a bacterium, behaving almost like a bacterial gene. It is therefore replicated as part of the host's DNA and so multiplies at the same time. But certain agents (such as ultraviolet radiation) can turn the 'latent' viral DNA, called the prophage, into a vegetative form which multiplies, destroys its host, and is released to infect other bacteria.