Ira Herskowitz

Ira Herskowitz (July 14, 1946 – April 28, 2003) was an American phage and yeast geneticist who studied genetic regulatory circuits and mechanisms. He was particularly noted for his work on mating type switching and cellular differentiation, largely using Saccharomyces cerevisiae as a model organism.

Education Ira Herskowitz and his twin brother Joel were born in Brooklyn, New York

Ira Herskowitz became interested in bacteriophages when he studied with Robert Stuart Edgar at California Institute of Technology. After completing a degree in 1967, he entered Massachusetts Institute of Technology (MIT), where he studied the molecular biology of the lambda phage. Herskowitz worked with Ethan Signer, whose other students include Nancy Kleckner and Frederick M. Ausubel. He received his Ph.D. from MIT in 1971. He spent his final year at MIT working with David Botstein. Herskowitz and Botstein attended the Cold Spring Harbor Laboratory's yeast course together. This was one of the earliest examples of positive control of gene expression, and suggested that late gene expression required circularization. Herskowitz further described the products of the N, cII, and cIII genes, positive regulation of cII and cIII, and N's central role as a positive regulator for rightward and leftward transcription in lambda phage.

Yeast cells are comparable of switching between two different types. Herskowitz identified the mechanism of the mating of yeast in homothallic strains, describing it via the "cassette model" metaphor. According to this metaphor, a cell possesses a "library" of "cassettes" with both types of genes. Only one "cassette" can be "played" at a given time and influence cell behavior, but both exist in the library. The "cassette" that is not being "played" is "silent" or "hidden". The cell changes types by putting in a different "cassette", replacing the functional section of genetic information with information from one of the silent copies The cassette model became a paradigm for the control of differentiation in eukaryotic regulatory systems. Herskowitz studied many other areas through the mechanisms of yeast mating, including signal transduction, control of the eukaryotic cell-cycle, RNA transport, the role of chromatin in transcription, meiosis, sporulation, gene expression, and how human genetic variation leads to different responses to drugs. 1987 MacArthur Fellows Program 1988 Genetics Society of America Medal

1991 Mendel Medal 2002 Thomas Hunt Morgan Medal 2002 Lewis S. Rosenstiel Award for Distinguished Work in Basic Medical Research.