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| DNA Mutation, Repair and the Environment |
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SPEAKER:
Leona Samson
Director, Center for Environmental Health Sciences;
Professor of Toxicology, and Biological Engineering
Ellison American Cancer Society Professor
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ABOUT THE LECTURE:
Forget cigarette smoking (well, not completely). The really bad news, says Leona Samson, is that by virtue of the act of living, a human body will be exposed to destructive threats from the environment, and from within itself. Charbroiled burgers, sunlight, pollution, and even how our bodies use oxygen all pose what Samson calls “insults” to the DNA of our cells.
Our success in fending off these inevitable DNA-damaging agents in the environment depends a lot on inheritance, Samson tells us. For instance, victims of the rare disease Xeroderma pigmentosum don’t have the capacity to repair DNA that’s been corrupted by UV radiation from the sun. Children with Xeroderma pigmentosum develop skin cancers. In the larger population, such cancers tend to occur much later in life. The reason, Samson says, is that most of us have a formidable array of mechanisms within our cells for detecting and mending defective DNA. Cells with flawed DNA that goes unrepaired must either die, or go on to mutate in often dangerous ways.
Samson wants to figure out how to protect cells against carcinogenic effects in the environment, and whether a tumor cell will be susceptible to treatment. She has been painstakingly studying the Saccharomyces cerevisiae yeast organism, trying to identify all the factors that determine whether or not DNA damaging agents kill or mutate cells. She interrogated each of this organism’s 5,800 genes, “asking one by one, which of you is making a product that’s important to helping a cell recover from damage.” In what was a “huge surprise,” Samson learned that there are more than 2,000 gene products involved in helping a yeast cell repair itself, “from areas of the cell never suspected before for being important” in this way. Now Samson must elucidate the complex cellular pathways that “talk to each other” when DNA is damaged -- and figure out “how to extend to humans, ultimately.”
ABOUT THE SPEAKER:
Leona Samson became Director of the MIT Center for Environmental Health Sciences in 2001. She is also an
Affiliate at the MIT Center for Cancer Research and an
Adjunct Professor of Toxicology at the Harvard School of Public Health.
Her research aims at understanding how cell, tissues, animals and ultimately people respond upon exposure to environmental toxicants in general, and alkylating agents in particular. A wide variety of DNA repair pathways provide protection against DNA alkylation damage and it is now clear that a multitude of other pathways are important for cellular recovery. Samson's goal is to understand how these pathways function, how they are regulated, and how they integrate to determine the ultimate biological and health consequences of environmental exposures.
Samson received a B.Sc. in Biochemistry from Aberdeen University, Scotland in 1974, and her Ph.D. in Molecular Biology from the Imperial Cancer Research Fund and University College, London University, England, in 1978.
Samson's Biological Engineering website
NOTES ON THE VIDEO (Time Index):
Video length is 47:21.
Tyler Jacks introduces Leona Samson.
At :48, Samson begins.
The audience poses questions to her on several occasions.
At 38:26, she invites questions.
Note: There are several times when audio from a different (and phantom) source interrupts Samson’s talk, most noticeably at 33:51 and at the end.
The information on this page was accurate as of the day the video was added to MIT World. This video was added to MIT World on 2006-10-11.
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