Word: teminism
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Unable to reproduce themselves, viruses invade normal cells and use their hosts' chemical mechanisms to produce more viruses. Eventually, the infected cell ruptures, releasing the newly formed viruses to infect other cells. Dr. Howard Temin of the University of Wisconsin has shown that some tumor viruses behave differently. They reverse the normal order of genetic transmission, and with the aid of a recently discovered enzyme, use their RNA messenger molecules to produce DNA, the double-helix master molecule. In a way not yet understood, this triggers the cellular genetic machinery to order cell division, causing the cancerous growth that...
...enzyme associated with Temin's discovery was at first believed to be unique to cancer cells infected by viruses. Thus when Columbia University's Sol Spiegelman and the National Cancer Institute's Robert Gallo found high enzyme activity in the cells of leukemic patients, medical science had a solid clue that leukemia might be caused by a virus. Even more important, some researchers speculated that if the Temin enzyme was found only in cancer cells, the spread of cancer might be halted simply by inhibiting the enzyme...
...Temin thinks he knows why it occurs. According to his hypothesis, normal cells manufacture RNA, which moves to neighboring cells in the form of a protovirus, or template, and stimulates the production of a new form of DNA. But, theorizes Temin, if this wandering RNA somehow transmits the wrong message after entering the cells, it can cause the production of altered DNA that orders the cells to grow abnormally...
Deadly Message. Gallo's hypothesis tends to support the iconoclastic ideas of Howard Temin, a University of Wisconsin molecular biologist who long espoused what his colleagues considered a major heresy. According to accepted theory, the hereditary information in the chromosomes of all cells passes in the same direction. Double-stranded DNA molecules make single-stranded messenger RNA molecules, which then direct the production of proteins, the basic building blocks of every cell. Temin contended that the process is sometimes reversed: RNA, he insisted, could make DNA. Otherwise, he asked, how could cancer-causing viruses−which consist of bundles...
Last summer Temin and other molecular biologists produced strong experimental evidence that RNA viruses may indeed be capable of producing their own DNA (TIME, July 20). Columbia University's Sol Spiegelman confirmed it. He demonstrated how an enzyme, or natural chemical catalyst, can cause tumors in laboratory animals by a DNA-RNA reversal. As Temin had postulated, the enzyme turned out to be RNA-dependent DNA polymerase. But a question remained: Was the same enzyme also present in human cancer...