- Neé:
- Evelyn Maisel
- Born:
- March 9, 1921, New York City, New York, U.S.
- Died:
- July 8, 2023, Plainsboro Township, New Jersey (aged 102)
- Subjects Of Study:
- DNA
- DNA repair
- mutation
Evelyn M. Witkin
-
Who was Evelyn M. Witkin?
Evelyn M. Witkin (1921–2023) was an American geneticist known for her work on mutagenesis, the process of mutation induction. Her research provided insights into DNA repair mechanisms, which are essential for living organisms to maintain their genetic integrity and survive. Witkin's discoveries contributed to the understanding of how bacteria adapt to their environment, including surviving exposure to ultraviolet (UV) radiation and antibiotics.
Witkin received the National Medal of Science in 2002 and the Albert Lasker Basic Medical Research Award in 2015. She was elected to the U.S. National Academy of Sciences in 1977 and the American Academy of Arts and Sciences in 1978. In 1979, she became the Barbara McClintock Professor of Genetics at Rutgers, retiring as professor emerita in 1991.
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What field of science did Evelyn M. Witkin work in?
Evelyn M. Witkin was an American geneticist whose work focused on mutagenesis in bacteria, which provided insight into DNA repair mechanisms. Her discoveries contributed to the understanding of how bacteria adapt to their environment, including survival of exposure to ultraviolet (UV) radiation and antibiotics. Witkin's work supported the idea that a control mechanism involves lexA, which represses the activity of SOS response genes, and recA, which responds to DNA damage by eliminating lexA repression. She received the National Medal of Science in 2002 and the Albert Lasker Basic Medical Research Award in 2015.
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What is genetics and why is it important?
Genetics is the study of genes, heredity, and how traits are passed from parents to offspring. It explores genes at every level, including their actions within cells and their transmission between generations. Genetics is a central pillar of biology that overlaps with agriculture, medicine, and biotechnology.
Understanding genetics is crucial because genes determine all aspects of an organism's makeup. Genetic research has shown that virtually all organisms on Earth have similar genetic systems. Humans have improved medicines, foods, and textiles by applying selective breeding and recombinant DNA technology to plants, animals, and microbes.
Evelyn M. Witkin (1921–2023) was an American geneticist known for her research on mutagenesis. Her discoveries were central to understanding how bacteria adapt to their environment, including how they survive exposure to ultraviolet (UV) radiation and antibiotics.
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What important discovery did Evelyn M. Witkin make about DNA?
Evelyn M. Witkin, an American geneticist, made significant contributions to understanding DNA repair mechanisms. Her groundbreaking research on mutagenesis in bacteria provided insight into how living organisms maintain their genetic integrity to survive.
In the early 1960s, Witkin discovered that UV mutagenesis in E. coli could be reversed through dark exposure, describing it as "dark repair" to distinguish it from photoreactivation. In 1967, she proposed that the UV-induced block of cell division resulted from the inhibition of a DNA replication enzyme. Her work supported the idea that the control mechanism involves lexA, which represses the activity of SOS response genes, and recA, which responds to DNA damage by eliminating lexA repression.
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How did her research help us understand how cells repair DNA damage?
Evelyn M. Witkin's research provided key insights into how cells repair DNA damage. She discovered "dark repair," the reversal of UV mutagenesis in E. coli through dark exposure, distinguishing it from photoreactivation.
Her work suggested that UV-induced cell division block resulted from the inhibition of a DNA replication enzyme. This concept was further developed in Miroslav Radman’s SOS replication model, which explains how bacteria survive extensive DNA damage.
Witkin's work supported the idea that a control mechanism involving lexA and recA regulates cellular responses to UV mutagenesis. Her findings were confirmed by other researchers and applied to the study of DNA repair mechanisms in other organisms.
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Why is Evelyn M. Witkin's work still important for science and medicine today?
Evelyn M. Witkin's work remains important to science and medicine because her research on mutagenesis in bacteria offered key insights into DNA repair mechanisms. Her discoveries contributed to the understanding of how bacteria adapt to their environments, notably in their resistance to ultraviolet (UV) radiation and antibiotics. Witkin's work supported the idea that a control mechanism involving lexA and recA regulates cellular responses to UV mutagenesis. Subsequent researchers confirmed these findings and applied them to the study of DNA repair mechanisms in other organisms.
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Evelyn M. Witkin (born March 9, 1921, New York City, New York, U.S.—died July 8, 2023, Plainsboro Township, New Jersey) was an American geneticist whose groundbreaking research on mutagenesis (the induction of mutations) in bacteria provided insight into mechanisms of DNA repair, the fundamental process by which living organisms maintain their genetic integrity in order to survive. Witkin’s discoveries were central to the basic understanding of how bacteria adapt to their environment, including how they survive exposure to ultraviolet (UV) radiation and antibiotics (see antibiotic resistance). Her discoveries played a key role in the elucidation by other researchers of DNA-damage responses in eukaryotic cells.
Education and early discoveries
Maisel was raised in Manhattan and later Queens in New York City. At age 16 she began undergraduate studies at New York University (NYU) and in 1941 completed a bachelor’s degree there. She planned to remain at NYU for graduate studies, but a suspension received during her senior year for protesting against NYU’s acquiescence to segregation in Southern schools during athletic events caused her to enroll instead at nearby Columbia University, where she earned a master’s in 1943. That same year she married psychologist Herman A. Witkin, with whom she later had two children.
Evelyn remained at Columbia to carry out her doctoral research, working in the laboratory of Ukrainian American geneticist Theodosius Dobzhansky, who was widely known for his influential research on genetics and evolution in Drosophila flies. In 1943, for a class assignment, Dobzhansky asked Witkin to report on a paper by biologists Salvador Luria and Max Delbrück. The paper described the first experimental evidence for the existence of mutable genes in bacteria. Witkin was intrigued by the finding and decided to spend the following summer studying bacterial genetics at Cold Spring Harbor Laboratory under the guidance of Dobzhansky’s colleague, Croatian American geneticist Milislav Demerec. In initial experiments, Witkin induced mutations in Escherichia coli bacteria using UV light and performed the first successful isolation of UV-resistant E. coli mutants. In 1944, Witkin having completed her course work at Columbia and Dobzhansky’s laboratory being unequipped for bacterial research, she returned to Cold Spring Harbor to pursue her thesis work. She subsequently discovered that UV-sensitive E. coli cells become elongated and filamentous and are prevented from undergoing cell division prior to dying from UV irradiation. The observation would prove critical to her later work. Witkin graduated with a Ph.D. from Columbia in 1947.
Research on UV mutagenesis and the SOS response
In 1949, following postdoctoral studies at the American Cancer Society, Witkin resumed the study of bacterial genetics at Cold Spring Harbor. In 1955 she joined the faculty of medicine at the State University of New York Downstate Medical Center. There in the early 1960s she discovered that UV mutagenesis in E. coli could be reversed through dark exposure, a phenomenon that she described as “dark repair” in order to distinguish it from photoreactivation (the elimination of UV mutagenic effects via visible light-dependent enzymatic reactions). She also built on her earlier observations in UV-sensitive E. coli, proposing in 1967 that the UV-induced block of cell division was due to the inhibition of a DNA replication enzyme that, if left active, would otherwise introduce mutations into DNA during the replication process. That possibility was considered in Croatian French biologist Miroslav Radman’s model of so-called SOS replication, which he initially proposed in 1970 by memorandum to Witkin. According to Radman, SOS replication provides bacteria with a means of surviving sudden and extensive DNA damage, and it displays unique characteristics—it is inducible (triggered by DNA damage), requires the synthesis of new proteins, and is controlled by genes known as lexA and recA.
After learning of Radman’s SOS model, Witkin worked to identify a common control mechanism in bacteria that regulates the seemingly disparate cellular responses to UV mutagenesis. Her work supported the idea that the control mechanism involves lexA, which under normal conditions represses the activity of SOS response genes, and recA, which responds to DNA damage by eliminating lexA repression. Other researchers subsequently confirmed her findings and applied them to the study of DNA repair mechanisms in other organisms.
Awards and honours
Witkin received many awards and honours during her career, including the National Medal of Science (2002) and the Albert Lasker Basic Medical Research Award (2015). She was elected to the U.S. National Academy of Sciences in 1977 and the American Academy of Arts and Sciences in 1978. In 1979 she was named the Barbara McClintock Professor of Genetics at Rutgers, where she retired in 1991 as professor emerita.