Howard Temin: The Heretic Who Rewrote the Central Dogma
Howard Martin Temin (1934–1994) was a visionary virologist and geneticist whose work fundamentally altered our understanding of molecular biology. At a time when the "Central Dogma" of biology—that genetic information flows strictly from DNA to RNA to protein—was considered sacrosanct, Temin proposed a "heretical" alternative. His discovery of reverse transcription not only earned him a Nobel Prize but also provided the essential tools for modern biotechnology and the fight against retroviruses like HIV.
1. Biography: From Philadelphia to Madison
Howard Temin was born on December 10, 1934, in Philadelphia, Pennsylvania. His father was an attorney and his mother was a civic activist, fostering an environment of intellectual curiosity and social responsibility.
Education and Formative Years
Temin’s scientific aptitude emerged early. As a high school student, he attended summer sessions at the Jackson Laboratory in Bar Harbor, Maine, where he first encountered formal biological research. He attended Swarthmore College, majoring in biology, and graduated in 1955.
He moved to the California Institute of Technology (Caltech) for his graduate studies, working under the tutelage of the renowned virologist Renato Dulbecco. It was here that Temin began studying the Rous Sarcoma Virus (RSV), a virus known to cause tumors in chickens. He earned his PhD in 1959.
Academic Career
In 1960, Temin joined the McArdle Laboratory for Cancer Research at the University of Wisconsin-Madison. Despite lucrative offers from more prestigious coastal institutions later in his career, Temin remained at UW-Madison for the rest of his life, rising to the rank of Professor of Oncology. He was known for his modest lifestyle, famously riding his bicycle to work every day regardless of the harsh Wisconsin winters.
2. Major Contributions: The Provirus Hypothesis
Temin’s primary contribution was the discovery that certain viruses could reverse the flow of genetic information.
The Provirus Hypothesis (1964)
While studying RSV, Temin noticed that the virus (which carries its genome as RNA) could permanently alter the genetic makeup of the host cell. He proposed that the virus was creating a DNA copy of its RNA genome and integrating that copy into the host cell's DNA. He called this integrated state a "provirus."
For six years, the scientific community largely ridiculed or ignored this theory. It contradicted the Central Dogma established by Francis Crick, which held that information could not flow "backward" from RNA to DNA.
The Discovery of Reverse Transcriptase (1970)
In 1970, Temin and his post-doctoral fellow Satoshi Mizutani performed the definitive experiment. They isolated an enzyme within the RSV particle that synthesized DNA from an RNA template. Simultaneously and independently, David Baltimore at MIT discovered the same enzyme in a different virus. This enzyme, reverse transcriptase, provided the physical proof for Temin’s provirus hypothesis.
3. Notable Publications
Temin was a prolific writer known for the precision of his logic. His most influential works include:
- "The nature of the provirus" (1964): Published in Proceedings of the National Academy of Sciences. This was the initial, controversial proposal of the provirus hypothesis.
- "RNA-dependent DNA polymerase in virions of Rous sarcoma virus" (1970): Published in Nature. This landmark paper (alongside Baltimore’s) announced the discovery of reverse transcriptase.
- "The RNA tumor viruses—background and foreground" (1971): A comprehensive review in Science that helped define the field of retrovirology.
- "Origin of retroviruses from endogenous retroelements" (1980): This work explored how retroviruses might have evolved from mobile genetic elements (transposons) within the host genome.
4. Awards & Recognition
Temin’s validation of the provirus hypothesis led to a rapid accumulation of honors:
- Nobel Prize in Physiology or Medicine (1975): Awarded jointly with David Baltimore and Renato Dulbecco "for their discoveries concerning the interaction between tumour viruses and the genetic material of the cell."
- Albert Lasker Basic Medical Research Award (1974): Often called the "American Nobel."
- National Medal of Science (1992): Awarded by President George H.W. Bush for his contributions to the understanding of the molecular basis of cancer.
- Election to the National Academy of Sciences (1972): One of the youngest members ever elected at the time.
5. Impact & Legacy
Howard Temin’s work laid the foundation for several pillars of modern science:
- Retroviruses and HIV: The discovery of reverse transcriptase was essential to identifying HIV as a retrovirus in the 1980s. It also allowed for the development of antiretroviral drugs (like AZT), which specifically target the reverse transcriptase enzyme.
- Biotechnology Revolution: Reverse transcriptase is a "workhorse" enzyme in molecular biology. It is used in RT-PCR (Reverse Transcription Polymerase Chain Reaction) to detect RNA viruses (including COVID-19) and in creating cDNA libraries for cloning and gene expression studies.
- Gene Therapy: Retroviruses are used as "vectors" to deliver healthy genes into the DNA of patients with genetic disorders, a direct application of the "provirus" integration mechanism Temin discovered.
- Cancer Research: Temin helped prove that viruses could cause cancer by altering the host's genome, leading to the discovery of oncogenes.
6. Collaborations
- Renato Dulbecco: As Temin's PhD advisor, Dulbecco provided the rigorous training in quantitative virology that allowed Temin to question existing dogmas.
- David Baltimore: While they were competitors in the race to find the enzyme, their simultaneous publication in Nature solidified the discovery. They remained lifelong colleagues and shared the Nobel Prize.
- Satoshi Mizutani: Temin’s post-doctoral researcher who was instrumental in the laboratory work that identified reverse transcriptase in 1970.
- The McArdle Laboratory: Temin fostered a collaborative environment at UW-Madison, mentoring dozens of students who went on to lead major labs in virology and genetics.
7. Lesser-Known Facts
- The Anti-Smoking Crusade: Temin was a fierce opponent of cigarette smoking. During his Nobel Prize acceptance speech in Stockholm, he famously deviated from scientific protocol to publicly rebuke the guests for smoking, stating:
"it was 'ironic' to honor cancer research in a room full of people increasing their cancer risk."
- A Cruel Irony: Despite being a lifelong non-smoker, Howard Temin died of lung cancer (specifically adenocarcinoma) on February 9, 1994, at the age of 59.
- The Temin Path: At the University of Wisconsin-Madison, a scenic walking and biking path along Lake Mendota is named the "Howard Temin Lakeshore Path" in his honor, commemorating his habit of biking to work.
- Scientific Humility: Even after winning the Nobel Prize, Temin refused to have a private office for many years, preferring to sit in the laboratory with his students to stay close to the actual data.