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David Prescott

Fundamentals of Teaching

Eat Your Fruits and Vegetables!

The Life of a Cell Biologist
CU-Boulder's David Prescott

"I'm a piece of history," President's Teaching Scholar David Prescott declares. Prescott has lived—and helped create—the history of modern biology. At 72, the professor of molecular, cellular, and developmental biology (MCDB) remains an indefatigable researcher and teacher, eager to enter his laboratory each day and to interact with his student researchers.

After three years as chair of the Medical School's anatomy department, Prescott was invited to the Boulder campus. Boulder "was a fairly sleepy campus in 1966," compared to its research activity today, he says.

"Boulder's biology department was a very traditional one, and the field of biology in 1966, when I came here, was on the verge of an explosion, and some of us felt that coming. New ventures in research in biology and also in teaching biology were being supported by the National Institutes of Health and the National Science Foundation, so there was national funding available for a university that wanted to rev up its biology department and get into the new areas of biology"—primarily molecular, cellular, and developmental biology. These fields were "given their impetus by the discovery of DNA material and the awareness that knowledge of DNA and how it works and explains genetics was going to be a powerful platform for advances in understanding life and human diseases and human health."

CU-Boulder won federal funding and developed the Institute for Developmental Biology, MCDB's precursor. Soon the university hired Keith Porter from Harvard to head the new department. "One thing led to another; it just grew and grew and grew, and here we are."

Prescott also has seen changes in students, toward whom he displays a passionate commitment. He says the quality and interest of biology majors has increased. Nevertheless, "a lot of students are ill-prepared when they arrive. These ill-prepared students aren't dumb; they're smart students. They just got cheated by the public school system."

When Prescott first started teaching at Boulder, he occasionally had an undergraduate or two working in his lab. "Not infrequently, it didn't work out," and not many asked to do independent study. In recent years, that picture has changed. On a mid-summer day, in the lab adjacent to his office, a half dozen student researchers are bent over lab tables replete with the tools of scientific detectives, the only audible sound the white noise of Porter's HVAC system. Prescott has ten student researchers for the summer and the fall, whose abilities he extols: "They are superb. These are bright, energetic, creative, original, smart students. I couldn't have found them as little as ten years ago."

Although what biologists teach students will change over time, Prescott doesn't predict change in the philosophy or goals of instruction, which include teaching about biology's impact on human affairs—for example, human cloning. "We're gaining in biology more and more control over what organisms are and how they behave. And we can do that for the welfare of humankind, but there are things that I believe we shouldn't touch. For example, I am an extremely strong opponent of human cloning."

After a pause of several seconds, he continues, "Human cloning raises some very serious issues. I don't think humans are capable of dealing in a rationale, sensible way with the issues of human cloning; therefore, we shouldn't do it. But there are plenty of other things to do. We've made a mess of this earth, and now we've got to try to clean it up, and biology will make a contribution to that."

Prescott's contributions are to the study of DNA and cancer. "Cancer is a genetic disease because it happens when mutations occur in certain genes in a cell." The root of cancer, in short, is genetic change in a cell. Researchers in Prescott's lab are engaged in understanding what the genetic changes are and "how they make the cell misbehave—become a cancer cell." They're interested in genetic changes because they're related to the formation of a cancer cell, but they're also interested in how DNA changes in evolution.

"We're finding out that there's a wisdom in DNA that we didn't know about before" that reflects "a kind of intelligence," that makes it a major agent in evolution. "In a sense, DNA is always experimenting with itself—to find a way to make a better gene, a better organism."

As he talks about the nature of DNA, Prescott unearths a favorite Lewis Thomas quotation from his desk: "The capacity to blunder slightly is the real marvel of DNA. Without this special attribute, we'd still be anaerobic bacteria, and there would be no music." Prescott knew the popular science writer/physician Thomas when Thomas was dean of New York University's medical school.

The protozoa Prescott studies ("these guys," as he refers to them) "do spectacular things with DNA. These protozoa are extremely successful in nature. They'll be around long after all humans are gone from this planet. In a sense, they've planned ahead for all kinds of emergencies." They're extraordinarily resistant to radiation, for example. Recently, Prescott has been collaborating with an assistant professor of biochemistry at Princeton and a computer scientist at the University of Chicago. The three researchers are studying how the organisms they work with manipulate and change their DNA regularly in complex ways. These organisms are operating "by rules that no computer scientists can yet design a computer program to solve."

What does this veteran researcher make of the recent flurry of reports about cancer research "breakthroughs"? "I began my career in cancer research in 1952 as a graduate student," Prescott begins. "Through the years I've seen dozens of breakthroughs, and all of the breakthroughs I've seen have fizzled. There's been steady progress in the struggle with cancer," he acknowledges. "But it's still a terrible, big tragedy," he says, true emotion modulating his voice, "the fact that 560,000 people will die this year of cancer. . . . Each one of them is a big tragedy."

Various discoveries have given researchers more knowledge about how cancer works and what causes it, but they haven't helped humankind devise a treatment. The most exciting developments, he says, are coming from the lab of Judah Folkman, which announced that its team had cured cancer in mice by using a substance that blocks the ability of blood vessels to grow into a tumor. "It's a rational, good approach, because there are no side effects," as opposed to current "slash, burn, and poison" (surgery, radiation, and chemotherapy) treatments.

"The big hope in cancer is preventing it," Prescott insists, adding that 70 to 80 percent of cancer is preventable if people would adopt appropriate lifestyles. Prescott's personal as well as professional mission has been to spread the word about preventive tactics that can control environmental factors known to cause cell mutation: poor diet, smoking, and occupational exposure to cancer-causing agents.

Prescott himself has changed his lifestyle over the years. "I never smoked. I don't have the genetic makeup to be easily addicted to nicotine. But I've changed the way I eat. I stay out of the sun. I always wear a broad-brimmed hat. . . . I exercise." (For specific lifestyle recommendations, see the sidebar.) "I get very wound up about this," Prescott admits, in the middle of his well-practiced speech on lifestyle adjustment.

When asked the secret to being a great teacher and researcher, Prescott, who has won just about every award that the university and the profession can bestow, answered: "There's no special thing about being successful; it's just being enthusiastic about what you're doing. If you're enthusiastic, you'll work hard."

"I was a mediocre student in high school," he recalls. After high school, he joined the merchant marine in the middle of World War II and spent three years as a radio operator on ships sailing around the world. Then, having "nothing better to do," he went to college, where he took a course in biology, which he'd never studied before. That fortuitous decision shaped the rest of his career.

"It's a privilege to have a position where you like what you're doing," Prescott believes. "That's what I've always had."

If given the opportunity to revise his career, Prescott says he'd do "fundamentally nothing" different. "I wasted some time going down wrong roads, but I don't think it was a waste. Maybe the one thing I would have done would have been to have left here and gone to a different university. (Over the years, Prescott has been courted by a number of other prestigious institutions, including the University of Chicago, Northwestern, and Princeton.) Things always look greener in other pastures."

In spite of the natural "what ifs," Prescott's pasture looks respectably green. As he looks out his office window toward the Student Recreation Center, he comes back to students: "I like working with students in the lab. It's very refreshing. Teaching in the lab is the most important kind of teaching I do. Socratic teaching is, in my view, the best way, and I can do that in the lab." Lab teaching, he says, teaches students to think, to take a hypothesis, test it, conduct the procedures, analyze the data, and apply the data to the original hypothesis. "It's a process of learning to think."

Prescott's tenure at CU has enriched the lives of countless students and faculty members. The most recent acknowledgment of that was Karen Lynn Kelminson's winning a Jacob Van Ek Award last May for outstanding academic achievement and contributions to the university. The Van Ek awards also recognize the student's primary faculty mentor, who, in Kelminson's case, was Prescott.

Students accepted into Prescott's lab have a strong record of earning honors. He'll only take students who commit to working with him for three years—under the auspices of the Undergraduate Research Opportunities Program, other fellowships, or his own research funds—and he expects them to write a thesis and graduate with honors. "They learn a kind of thinking that will stick with them for the rest of their lives. That method is applicable to politics, to anything in their lives . . . and that's the most important kind of teaching you can do."

Fundamentals of Teaching
Chalkboard Animation Wins over Slide Shows

John J. Cohen, School of Medicine, Health Sciences Center Campus

In medical school, slides are de rigeur in the lecture hall. But for my class of 185 students, I don't use slides, because you have to dim the lights, and then you can't see the students (and whether they're awake and getting the point). Worse, you can put too much in a slide, and then the students are dismayed. Finally, slides fashionably made in PowerPoint using "Wizards," replete with ribbons and bubbles, look to me like a series of cocktail napkins.

Instead, I write and draw on the chalkboard, because that happens at a natural tempo for the human hand and mind to follow. Making a drawing, adding to it, erasing bits and replacing them—it's the cheapest form of animation there is. And, at a deeper level, the drawing is the concept, while the photo is the thing, and we try to teach concepts.

Overwhelmingly, student evaluations say they prefer the chalkboard to slide shows. For courses that require the exhibition of vast numbers of images, perhaps the lecture is not the best format.

Eat Your Fruits and Vegetables!

Results from more than 200 studies worldwide on fruits and vegetables in the diet are consistent: Populations consuming a diet rich in fruits and vegetables have half the cancer rate of populations that eat few fruits and vegetables and which, instead, eat more meat. Evidence is mounting that certain chemicals in fruits and vegetables block the onset of cancer and that a high-fat diet promotes cancer.

Cancer-Prevention Tips

• Stay out of the sun.
• Don't smoke.
• Eat plenty of fruits and vegetables, especially cruciferous ones such as broccoli and cauliflower.
• Minimize red meat and other sources of fat in your diet. (Drink skim rather than full or 2% milk.)
• Avoid mushrooms and bean sprouts, which contain potent carcinogens.
• Get regular exercise. (Epidemiological studies have shown that women who exercise three or more hours a week reduce the risk of breast cancer by half.)

"Some things," Prescott admits, "are hard to do. We're all creatures of habit." But, he insists, we can change our habits. If adhering to the best advice on a cancer-prevention lifestyle seems daunting, Prescott advises changing gradually: "I think you defeat yourself if you try to do it all at once."

Program Director: Mary Ann Shea   360 UCB, Boulder, CO 80309-0360   Phone: (303) 492-4985   E-mail: MaryAnn.Shea@Colorado.EDU