He joined the faculty of the University of California, Santa Barbara in 1968, and became professor emeritus in 1999. His research contributions include elucidation of the mechanism of genetic missense suppression in bacteria, the development of techniques to make genomic libraries using recombinant DNA, techniques for using yeast for DNA cloning, characterization of centromere DNA, and construction of the first artificial chromosomes. Many of his later research contributions were carried out in collaboration with his wife, Professor Louise B. Clarke.
He became a part of the University of California, Santa Barbara faculty in 1968, and was elevated to emeritus professor status in 1999. His scientific contributions encompassed elucidating genetic missense suppression mechanisms in bacteria, creating genomic libraries through recombinant DNA techniques, utilizing yeast for DNA cloning, analyzing centromere DNA, and constructing the first artificial chromosomes. Many of his subsequent research projects were undertaken jointly with his wife, Professor Louise B. Clarke.