Phage group

The phage group (sometimes called the American Phage Group) was an informal network of biologists centered on Max Delbrück that contributed heavily to bacterial genetics and the origins of molecular biology in the mid-20th century. The phage group takes its name from bacteriophages, the bacteria-infecting viruses that the group used as experimental model organisms. In addition to Delbrück, important scientists associated with the phage group include: Salvador Luria, Alfred Hershey, Seymour Benzer, Charles Steinberg, Gunther Stent, James D. Watson, Frank Stahl, and Renato Dulbecco. Bacteriophages had been a subject of experimental investigation since Félix d'Herelle had isolated and developed methods for detecting and culturing them, beginning in 1917. Delbrück, a physicist-turned biologist seeking the simplest possible experimental system to probe the fundamental laws of life, first encountered phage during a 1937 visit to T. H. Morgan's fly lab at Caltech. Delbrück was unimpressed with Morgan's experimentally complex model organism Drosophila, but another researcher, Emory Ellis, was working with the more elementary phage. During the next few years, Ellis and Delbrück collaborated on methods of counting phage and tracking growth curves; they established the basic step-wise pattern of virus growth (the most obvious features of the lytic cycle). In a retrospective article, Emory Ellis stated "Soon after Max Delbruck arrived at the Caltech Biology Division, intent on discovering how his background in physical sciences could be productively applied to biological problems, I showed him some step-growth curves. His first comment was ‘I don't believe it.’" However, as Ellis describes, Delbruck soon dispelled this initial reaction of disbelief by his own analysis of the phenomenon, and promptly joined in the work with enthusiasm, bringing to it his training in mathematics and physics, and intense interest in genetics. Their initial collaborative findings were published in 1939.