Concept 28 Some types of mutations are automatically repaired.

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Claud Rupert did seminal research on light-activated DNA repair systems. Richard Setlow did a lot of the early work on thymine dimer repair.

Richard Setlow was born in 1921 and grew up in the Bronx. Good grades in school qualified him for entrance into the Townsend Harris High School, which was later closed down by Mayor LaGuardia for elitism. He went to Swarthmore College with an interest in science and encountered an exceptional physics instructor. "So I became a physicist because you could explain things so beautifully," Setlow says.

After graduating from college in 1941, Setlow went to Yale to continue his study of physics. "There was a biophysics group being started in the physics department, and I thought that would be a lot of fun," Setlow recalls. "We spent a lot of time irradiating proteins and viruses and cells with ionizing radiation and with ultraviolet radiation."

Setlow received his Ph.D. in physics in 1947 and continued teaching physics and biophysics at Yale until 1961 when he left for the Oak Ridge National Laboratory because he "wanted to have more time for research because it was so much fun."

He first became interested in DNA repair mechanisms when someone at Oak Ridge asked him, " 'Hey Dick, what do you know about these crazy Dutchmen that are irradiating frozen solutions of thymine', and I had to confess I didn't know anything."

After researching the papers of the crazy Dutchmen, Setlow decided their conclusion -- that the thymine dimers they broke with UV irradiation was the same as cellular photoreactivation -- was wrong and set out to solve the problem. In 1964, he and his colleagues showed that bacterial cells repair thymine dimers with enzymes that remove the dimer and replace it with undamaged bases.

In 1974, Setlow moved to the Brookhaven National Laboratory(BNL) where he is still active in DNA repair and ultraviolet radiation research. In the 1990s, using a special hybrid fish sensitive to ultraviolet light, Setlow's team found that UV-A rays cause most melanomas, not UV-B rays that were previously thought responsible.

Because of his finding, Setlow thinks the large increase in melanoma incidence is not due to a thinning ozone layer, which only filters out UV-B rays. "My feeling is that the big increase in malignant melonoma comes about because of lifestyle changes," he says. People use sunblock to stay out longer in the sun, but sunblocks — even those that claim to block UV-A — "do not screen out the wavelengths that are probably inducing melanoma."

In 1998, Setlow retired from his administrative duties at BNL as the Associate Director for Life Sciences to devote more time to his research. Setlow also enjoys music, hiking, and volunteering at a camp for handicapped persons.

Among his many awards, Setlow was elected to the National Academy of Sciences in 1973, and became a Fellow of the American Association for the Advancement of Science in 1988.