Louis Siminovitch | The Canadian Encyclopedia


Louis Siminovitch

Louis Siminovitch, CC, OC, OOnt, FRS, FRSC, molecular biologist (born 1 May 1920 in Montreal, QC; died 6 April 2021 in Toronto, ON). Siminovitch served on various national and provincial research and educational organizations. As a founder of the field, his research centered on somatic cell genetics and on the molecular biology of mammalian cells. (See also Genetics.) He has had a major influence on the careers of numerous Canadian molecular biologists, including James Till and Ernest McCulloch with their groundbreaking stem cell research.

Elinore and Lou Siminovitch


Louis Siminovitch received his undergraduate and graduate education in chemistry from McGill University. After completing his PhD in 1944, he received a research fellowship at the National Research Council in Ottawa and at Ontario’s Chalk River Laboratories. From 1947 to 1953, he trained in molecular biology at the Institut Pasteur in Paris, where he shared in the discovery of bacteriophage lysogeny, a process related to how some viruses infect bacteria.


Louis Siminovitch moved to Toronto and joined the Connaught Medical Research Laboratories of the University of Toronto in 1953. In 1956 he began working at the Ontario Cancer Institute where he contributed to cancer and stem cell research. Siminovitch also joined the Department of Medical Biophysics at the University of Toronto. In 1969, he participated in the formation of the Department of Medical Cell Biology (now Molecular Genetics), acting as the department’s first chairman (1969-72). Siminovitch also helped establish the Department of Genetics at the Hospital for Sick Children as geneticist in chief (1970-85), and from 1983 to 1994 was director of research for the Samuel Lunenfield Institute at the Mount Sinai Hospital.


Louis Siminovitch published over 200 publications in books and leading scientific journals. He was also the editor of the scientific journals Virology and Molecular and Cellular Biology, and was a founding member of Science Forum, the now-defunct Canadian science journal.

Several awards have also been named after Siminovitch. The Siminovitch Prize (formerly the Elinore and Lou Siminovitch Prize in Theatre) was established in 2000 in honour of Louis Siminovitch and his late wife Elinore, who was a playwright. In 2021, the Dr. Lou Siminovitch Catalyst Award was announced by the Department of Molecular Genetics at the University of Toronto. In 2023, the Mount Sinai Hospital will launch the Lou Siminovitch Sinai 100 Chair.

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