n.
born Oct. 30, 1928, Wilmington, Del., U.S.
died Nov. 16, 1999, Baltimore, Md.
U.S. microbiologist.
He received a medical degree from Washington University. Working principally at Johns Hopkins University, he used the restriction enzyme isolated from a bacterium by Hamilton O. Smith to investigate the structure of the DNA of a monkey virus (SV40), the simplest virus known to produce cancer. His construction of a genetic map of the virus was the first application of restriction enzymes to the problem of identifying the molecular basis of cancer. He shared a 1978 Nobel Prize with Smith and Werner Arber .