Howard Martin Temin

Howard Martin Temin (1934-1994), American virologist and winner of the 1975 Nobel Prize in physiology or medicine, which he shared with American molecular biologist David Baltimore and Italian American virologist Renato Dulbecco for their discoveries concerning the action of viruses on the genetic structure of the cells they infect.

Temin was born in Philadelphia, Pennsylvania. In 1955 he earned a B.S. degree in biology, with honors, from Swarthmore College in Swarthmore, Pennsylvania. In 1959 he received a Ph.D. degree from the California Institute of Technology (Caltech) in Pasadena, where he was a student of Dulbecco's. After a year of postdoctoral studies at Caltech, Temin joined the faculty of the University of Wisconsin, Madison, where he remained for his entire career, advancing from assistant professor to full professor. His last appointment, in 1982, was to the Steenbock Professorship of the Biological Sciences.

Since 1953, when James D. Watson and Francis H. C. Crick revealed the structure and mechanism of deoxyribonucleic acid (DNA), virtually all researchers had held to the principle that DNA transmitted genetic information through ribonucleic acid (RNA). However, in 1965, while studying the Rous sarcoma virus, Temin discovered that RNA changed the DNA of the host cell by inserting its own genes. Temin was derided by his peers for his outlandish proposal but held to the idea of “reverse transcription.” In 1970, working with Satoshi Mitzutani, Temin found an RNA viral enzyme, which he called RNA-directed DNA polymerase, that copies genetic information to the host cell's DNA. Baltimore made the same discovery almost simultaneously in the Rauscher mouse-leukemia virus. Their findings were announced in May 1970 within days of one another; their papers describing these findings appeared back-to-back in the journal Nature in June 1970. RNA-directed DNA polymerase later became known as reverse transcriptase. Viruses that use this method of altering a host's DNA are called retroviruses, and the human immunodeficiency virus (HIV) is one example. The discovery of reverse transcriptase shed new light on the mechanism by which a normal cell is changed to a cancer cell. Normal cells can monitor their own growth relative to other cells and halt reproduction when a cell meets its neighbors. A retrovirus destroys this mechanism, and runaway growth is the result. Several strategies for treating cancer and acquired immunodeficiency syndrome (AIDS) rely on the findings of Temin and Baltimore.