David Baltimore Biography (1938-)


David Baltimore won the Nobel Prize in physiology or medicine in 1975. He shared the award with the virologist Renato Dulbecco and the oncologist Howard Temin for the ground-breaking discovery that genetic informationdoesn't just travel from DNA (deoxyribonucleic acid, which contains geneticinformation) to RNA (ribonucleic acid, which communicates DNA information toproteins), although that concept had been at the heart of modern genetic theory. Rather, Temin and Baltimore independently discovered that some viruses could replicate their RNA into the DNA of healthy cells, causing tumors. This process is known as reverse transcription and is catalyzed by the enzyme reverse transcriptase . Its implications had a great effect on the study of cancerand the role of viruses in causing the disease. Born March 7, 1938, in New York City to Richard Baltimore and Gertrude Lipschitz, David was a gifted student of science. While still in high school he attended a prestigious summer program for talented students of science at the Jackson Laboratory in Bar Harbor, Maine, where the focus was mammalian genetics. It was there that Baltimore decided to pursue a career in the research sciences and first met his future colleague, Howard Temin, also a student at the time.

Baltimore attended Swarthmore College in Pennsylvania and graduated in 1960 with high honors in chemistry. He started graduate work at the Massachusetts Institute of Technology (M.I.T.) but transferred after one year to the Rockefeller Institute, now called Rockefeller University, in New York. There he studied with Richard M. Franklin , who was a molecular biophysicist specializingin RNA viruses. Baltimore earned his Ph.D. in 1964 and returned to M.I.T. fora postdoctoral fellowship the following year.

Baltimore was interested in a specific group of RNA viruses, the picornaviruses, which include mengovirus and poliovirus, that do not have DNA but nevertheless seemed to reproduce in cells of complex organisms that carry their genetic information in DNA. Since 1964, Temin had been suggesting that RNA viruses could replicate themselves in DNA, but the scientific community disbelievedand even ridiculed him. Baltimore, however, persisted in looking for RNA orDNA enzymes in the genetic material of poliovirus to solve this riddle.

He continued his research in this area as a fellow at the Albert Einstein College of Medicine in the Bronx (1964-65) and as a research associate at the Salk Institute in California (1965-68). At the Salk Institute he met Renato Dulbecco , who had developed innovative techniques for examining animal virusesin the laboratory. He also met , a postdoctoral fellow studying vesicular stomatitis virus.

In 1968, Baltimore returned with Huang to Boston, where they were married. They have one daughter. Baltimore became an associate professor of microbiologyat M.I.T. and continued to focus his research on poliovirus. By 1970, however, a number of scientists had suggested that all RNA viruses might not be alike. Baltimore's focus on poliovirus therefore might not reveal clues to the behavior of other viruses. Baltimore began to classify RNA viruses according to their varying replication strategies. It was during his work on this project that he discovered an enzyme that enabled an RNA virus to replicate its single strand of RNA and thus become compatible with the double-stranded DNA ina sample of Rauscher murine leukemia virus. The enzyme was later called reverse transcriptase.

Meanwhile, Temin had independently demonstrated the same thing, using a sample of Rous sarcoma virus. In 1970, both scientists made the initial announcements of reverse transcription within days of each other, at separate conferences. One month later they published an article detailing their findings in thejournal Nature. The excitement of their news was instantaneous. Many scientists jumped to the conclusion that reverse transcription held the keyto a cure for cancer. But Baltimore and Temin were more reserved in their response. They knew that their work did not establish a direct link between viruses and cancer. Their discovery did, however, quickly become a key to the study of cancer. Baltimore immediately began to be recognized for his achievement. In 1972 he was promoted to full professor at M.I.T. and in 1973 he was awarded a lifetime research professorship by the American Cancer Society.

While continuing to study reverse transcriptase, Baltimore and his colleaguesat M.I.T. partially synthesized a mammalian hemoglobin gene. Other teams around the country were performing similar experiments at the same time, which raised the specter of genetic engineering . As a prominent figure in the scientific community, Baltimore became outspoken about the risks of genetic engineering. He was concerned that modern science--and biology in particular--mightbe misused. In 1975, he initiated a conference in which scientists attemptedto design a self-regulatory system regarding experiments with recombinant DNA. In 1976, the National Institutes of Health established a committee to oversee federally funded experiments in the field of genetic engineering. After winning the Nobel Prize in 1975, Baltimore continued to be honored for his work. He was elected to the National Academy of Sciences and the American Academy of Arts and Sciences in 1974. In 1983 he became the director of the Whitehead Institute for Biomedical Research, where he remained until 1990. In that position, he made significant advances in the field of immunology and synthetic vaccine research. In 1990 he became President of Rockefeller University.

Baltimore's career took a sudden turn in 1989 when it was revealed that the conclusions of a 1986 paper he had coauthored while still at M.I.T. were basedon falsified data. A young scientist, Margaret O'Toole, confronted Thereza Imanishi-Kari, also a coauthor of the article and a supervising scientist in the M.I.T. lab, with suspicions of misconduct. Imanishi-Kari denied any wrongdoing. Baltimore stood by Imanishi-Kari, and O'Toole was subsequently demoted,later claiming that her career had been ruined because she had spoken out against her superiors.

The matter was taken up by a House subcommittee and the Office of ScientificIntegrity, which eventually lent credence to O'Toole's suspicions. Baltimoreretracted the article but it was too late. Though he was cleared of any wrongdoing and though Imanishi-Kari was not prosecuted, Baltimore's name had beenattached to a major breach of scientific ethics. That Baltimore had earlier taken such a strong stand on the ethics of bioengineering was a particular irony not lost on the scientific community. In 1991, under pressure from the faculty, Baltimore resigned as President of Rockefeller University, though he remains a professor there and continues to do research.

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