Medical training and Rockefeller research
MacLeod was born in Nova Scotia and received his medical degree from McGill University in 1932. After two years of clinical training at Montreal General Hospital, he moved to New York in 1934 and joined Avery’s pneumococcal research programme.
References: [1]
Making transformation reproducible
Early transformation experiments worked inconsistently, limiting chemical analysis of the active material. MacLeod improved culture conditions and selected a reliable rough bacterial strain. This helped turn transformation into a reproducible, measurable process. He co-authored the 1944 paper with Avery and McCarty reporting heritable changes induced by a purified DNA fraction.
Research and medical education
In 1941 MacLeod became head of microbiology at New York University School of Medicine while maintaining his Rockefeller collaboration. At NYU he continued work on pneumococci and transformation and helped build a department combining research with medical teaching.
References: [1]