Howard Temin Research Articles

An interview with Nobel Laureate David Baltimore, PhD.

In an online interview, Nobel Laureate David Baltimore, Ph.D., reflected on his contributions to biomedical science that have had a major influence on the fields of molecular biology, virology, cancer, and immunology. Dr. Baltimore is President Emeritus and Distinguished Professor of Biology at the California Institute of Technology. Among other notable works, he discovered the critical nuclear transcription factor NF Kappa B and the Rag1 and Rag2 proteins that rearrange adaptive immune cell receptors.
 His career path, he says, evolved naturally, as math and science came easily to him. As a high school student, he participated in a summer program at the Jackson Lab in Bar Harbor, Maine, where he says he came away feeling that experimental biology was exciting and rewarding.
 “That's where I discovered that the frontiers of science, were not so distant; that I could actually make a discovery that nobody else in the world knew about,” he says. 
 And that he did. Independently, he and Howard Temin discovered the viral enzyme reverse transcriptase revising the canon of cellular information transfer. They published back-to-back papers in Nature demonstrating that this enzyme in virus particles could transcribe RNA to DNA. Both received a Nobel Prize for this work.
 In reflecting on his early experience evaluating how to work with recombinant DNA and how we should scientifically and safely approach gain of function research, he says, “We have to be very honest with ourselves about what might hold danger, and we have to control our instinct … to do anything we can to generate progress and understanding of life. …At the same time, we don’t want to hold back progress, and so there is a balancing.”
 Dr. Baltimore also discussed his optimism about vectored immunoprophylaxis as a strategy for prevention of HIV and his doubt that scalable strategies will be able to cure HIV. He also reflected on his philosophy for the training of young scientists and the successful training program that he developed at the Whitehead Institute.

50th anniversary of the discovery of reverse transcriptase.

The simultaneous discovery in 1970 of reverse transcriptase in virions of retroviruses by Howard Temin and David Baltimore was perhaps the most dramatic scientific moment of the second half of the 20th century. Ten years previously, Temin’s observation of cells transformed by Rous Sarcoma virus led him to the conclusion that retroviruses replicate through a DNA intermediate he called the provirus. This heretical hypothesis was greeted with derision by fellow scientists; Temin and Baltimore performed a simple experiment, rapidly reproduced, and convincing to all. Its result was a major paradigm shift—reversal of the central dogma of molecular biology. It immediately grabbed the attention of both the scientific and lay press. It also came at a key time for cancer research, at the start of the “War on Cancer.” As a theoretical base and fundamental molecular tool, it enabled a decade of (largely fruitless) search for human oncogenic retroviruses but laid the foundation for the discovery of HIV 13 years later, leading to the development of effective therapy. I had the good fortune, as a student in Temin’s lab, to witness these events. I am honored to be able to share my recollection on the occasion of their 50th anniversary.

The 50th anniversary of reverse transcriptase-and its ironic legacy in the time of coronavirus.

The 50th anniversary of reverse transcriptase-and its ironic legacy in the time of coronavirus.

Remembering Jan Svoboda: A Personal Reflection

The Czech scientist Jan Svoboda was a pioneer of Rous sarcoma virus (RSV). In the 1960s, before the discovery of reverse transcriptase, he demonstrated the long-term persistence of the viral genome in non-productive mammalian cells, and he supported the DNA provirus hypothesis of Howard Temin. He showed how the virus can be rescued in the infectious form and elucidated the replication-competent nature of the Prague strain of RSV later used for the identification of the src oncogene. His studies straddled molecular oncology and virology, and he remained an active contributor to the field until his death last year. Throughout the 50 years that I was privileged to know Svoboda as my mentor and friend, I admired his depth of scientific inquiry and his steadfast integrity in the face of political oppression.

The Discovery of Reverse Transcriptase.

In 1970 the independent and simultaneous discovery of reverse transcriptase in retroviruses (then RNA tumor viruses) by David Baltimore and Howard Temin revolutionized molecular biology and laid the foundations for retrovirology and cancer biology. In this historical review we describe the formulation of the controversial provirus hypothesis by Temin, which ultimately was proven by his discovery of reverse transcriptase in Rous sarcoma virus virions. Baltimore arrived at the same discovery through his studies on replication of RNA-containing viruses, starting with poliovirus and then moving to vesicular stomatitis virus, where he discovered a virion RNA polymerase. Subsequent studies of reverse transcriptase led to the elucidation of the mechanism of retrovirus replication, the discovery of oncogenes, the advent of molecular cloning, the search for human cancer viruses, and the discovery and treatment of HIV/AIDS.

From Slow Viruses to Prions

From Slow Viruses to Prions

A Retrospective: On Clinical Studies with 5-Fluorouracil.

See related article by Curreri et al., [Cancer Res 1958:18:478–484][1] . Visit the Cancer Research 75th Anniversary [timeline][2]. The 1950s saw the rise of rational drug design to target DNA synthesis in cancer cells. The concept was simple; cancer was replicating uncontrolled compared with

Retroviral Integrase: Then and Now.

The retroviral integrases are virally encoded, specialized recombinases that catalyze the insertion of viral DNA into the host cell's DNA, a process that is essential for virus propagation. We have learned a great deal since the existence of an integrated form of retroviral DNA (the provirus) was first proposed by Howard Temin in 1964. Initial studies focused on the genetics and biochemistry of avian and murine virus DNA integration, but the pace of discovery increased substantially with advances in technology, and an influx of investigators focused on the human immunodeficiency virus. We begin with a brief account of the scientific landscape in which some of the earliest discoveries were made, and summarize research that led to our current understanding of the biochemistry of integration. A more detailed account of recent analyses of integrase structure follows, as they have provided valuable insights into enzyme function and raised important new questions.

What history tells us XXXVI. Reverse transcriptase and Lamarckian scenarios of evolution.

The discovery in 1970 of reverse transcriptase was considered as a blow to the Central Dogma of molecular biology. But there was more in this discovery : the possibility to generate scenarios in which the genome would be modified (by insertion of reverse transcripts) following a functional adaptation of the cells (and organisms) to variations in their environment ; i. e. a lamarckian mechanism of evolution. Howard Temin, one of the discoverer of reverse transcriptase, was the first to explore this possivbility, without success. In 1988, John Cairns proposed a similar scenario to explain the rapid occurrence of adaptive mutations in bacteria. After some years of a hot debate, other, non-lamarckian, mechanisms were proposed to account for these observations. I try to explain the recurrence of these heterodox models.

Retrotransposons

June 27, 1970 was a significant day for our understanding of both the flow of information in biological systems and the evolution of eukaryotic genomes as this was the day that Nature published back-to-back papers reporting the discovery of an enzyme that copies RNA into DNA. This soon became known as reverse transcriptase and the RNA tumour viruses in which it was detected were renamed retroviruses. The realisation that retroviruses can convert their genomic RNA into DNA provided a route by which they could integrate into the chromosomes of infected cells as Howard Temin and his colleagues had proposed some years earlier. At the time it was thought that the ability to copy RNA into DNA would be confined to retroviruses. One of the more startling outcomes of whole genome DNA sequencing has been the discovery that eukaryotes can have more reverse transcriptase genes than genes coding for any other protein, and that the largest single component of many eukaryotic genomes has been generated by reverse transcription.

The Little Book of Viruses

The Little Book of Viruses

Hunting the elusive oncogene: a stroke of good luck

Hunting the elusive oncogene: a stroke of good luck

Arginine metabolism and sensing by mTOR in T cells

Arginine has been shown to play an essential role in T cells, as arginine depletion in the immune microenvironment has a negative effect on T cell function. The goal of this study was to characterize how T cells sense and metabolize arginine.Experiments were carried out using murine T cells stimulated by CD3 and CD28 as well as the lymphoma cell line EL4. Proliferation and IL‐2 ELISA was used to assess T cell function. Western Blots were performed to determine amino acid sensing by the mTOR pathway. To establish pathways of arginine metabolism, a stable arginine isotope was used and metabolic products were analyzed using GC‐MS. Metabolomic analysis by GC‐MS was used to identify any unsuspected signaling and metabolic pathways regulated by arginine. RT‐PCR was used to analyze expression of enzymes known to be involved in arginine metabolism.T cells stimulated in the absence of arginine fail to proliferate or increase production of IL‐2, and activated T cells increase their uptake of arginine. T cells differentially sense arginine, citrulline, and ornithine through mTOR. Urea cycle enzymes are not expressed in T cells. GC‐MS analysis showed that arginine is not a substrate for the Krebs cycle and potentially plays a role in fatty acid synthesis. This research was supported by a Howard Temin Award from NCI/NIH and a New Investigator Grant from the Leukemia Research Foundation.

Retroviruses and Aids: Evolution and Drug Resistance

John M Coffin is the American Cancer Society Professor and Distinguished Professor of Molecular Biology and Microbiology at Tufts University (Boston, MA, USA). He also serves as advisor on HIV and AIDS to the National Cancer Institute and to the HIV Drug Resistance Program (DRP), which he founded in 1997. He received his PhD in Molecular Biology from the University of Wisconsin, Madison, in 1972, where he worked on retroviruses in the laboratory of Howard Temin. He joined the Tufts faculty after 3 years with Charles Weissmann at the University of Zürich, Switzerland. In 1997, he was recruited to organize the DRP, of which he served as Director until 2005. He is well known for his work on retrovirus genetics, genome structure and evolution, and is author of more than 50 peer-reviewed publications, and senior editor of Retroviruses, the definitive text on the subject. In 1995, he was elected to the National Academy of Sciences in recognition of his contributions to the field of retrovirology.

Experimental Series and the Justification of Temin’s DNA Provirus Hypothesis

A notion of experimental series is developed, in which experiments or experimental sets are connected through experimental suggestions arising from previous experimental outcomes. To that end, the justification of Howard Temin’s DNA provirus hypothesis is examined. The hypothesis originated with evidence from two exploratory experimental sets on an oncogenic virus and was substantiated by including evidence from three additional experimental sets. Collectively these sets comprise an experimental series and the accumulative evidence from the series was adequate to justify the hypothesis by persuading the virology community of its veracity. The notion of crucial experiment is also discussed in terms of experimental series.

Early days in the pittendrigh laboratory

I came to Princeton as a graduate student in 1955, having just completed an undergraduate degree at Swarthmore College with a major in biology and enough courses in English literature to have majored in that as well. Biological education at Swarthraore was sterile at that time (although not always before or afterwards), and the courses offered were so dull that I almost abandoned the ambition which I had formed at the age of two to devote my life to the study of other living things. For a short period I flirted with the idea of writing as a career, but stuck with biology in spite of an almost complete lack of inspiration from the faculty. That decision was reinforced by several amazing classmates, particularly Howard Temin who had already done significant research and was enthusiastic about sharing its excitement. During my first year at Princeton, Pittendrigh was away on sabbatical leave; I took several more advanced, but still uninspiring courses and once again questioned my choice of

My Life in Science, Not the Restaurant Business

My Life in Science, Not the Restaurant Business

Ahead of the Curve: David Baltimore's Life in Science (review)

David Baltimore shared the Nobel Prize in Physiology or Medicine when he was thirty-seven, for work that he and, independently, the late Howard Temin did to discover and explain reverse transcriptase—the enzyme that allows RNA to make DNA. It was a discovery of remarkable significance. Baltimore was the founding director of the Whitehead Institute at MIT, which has become one of the best in the world. He was president of Rockefeller University, and is currently president of the California Institute of Technology. He is a virologist par excellence, well known as a mentor of outstanding young scientists, and a man of conscience who has been a statesman and policy leader for the biomedical research community worldwide. He understands principle, and he has learned to understand the need for compromise in the best sense in the policy arena.

Virology: Overview

Virology: Overview

From heresy to dogma in accounts of opposition to Howard Temin's DNA provirus hypothesis.

In 1964 the Wisconsin virologist Howard Temin proposed the DNA provirus hypothesis to explain the mechanism by which a cancer-producing virus containing only RNA infects and transforms cells. His hypothesis reversed the flow of genetic information, as ordained by the central dogma of molecular biology. Although there was initial opposition to his hypothesis it was widely accepted, after the discovery of reverse transcriptase in 1970. Most accounts of Temin's hypothesis after the discovery portray the hypothesis as heretical, because it challenged the central dogma. Temin himself in his Nobel Prize speech of 1975 narrates a similar story about its reception. But are these accounts warranted? I argue that members of the virology community opposed Temin's provirus hypothesis not simply because it was a counterexample to the central dogma, but more importantly because his experimental evidence for supporting it was inconclusive. Furthermore, I propose that these accounts of opposition to the DNA provirus hypothesis as heretical, written by Temin and others after the discovery of reverse transcriptase, played a significant role in establishing retrovirology as a specialized field.