Environmental Factor, August 2009, National Institute of Environmental Health Sciences
Program Kicks Off Active Learning Format for Summer Interns
By Laura Hall
NIEHS Summers of Discovery (http://www.niehs.nih.gov/careers/research/summers/) students got their first taste of the program's new emphasis on active learning during a July 1 seminar on DNA repair, presented by NIEHS Principal Investigator Thomas Kunkel, Ph.D. Participants listened to brief talks that tied together three hands-on exercises.
Kunkel was implementing the program's new active learning format by having the students directly involved in their learning experience. The seminar provided lots of opportunities for interactive discussion and allowed students to perform the procedures they are studying, instead of passively listening to information and viewing slides during a lecture.
Leading up to the first exercise, Kunkel discussed the mechanisms of DNA polymerase, which he described as "the world's smallest word processor." To illustrate his point, he challenged the students to see if they could approach the accuracy of the polymerases using word processing software on the laptops at their tables.
Kunkel explained that the DNA polymerases in a human cell replicate the six billion "letters" in the human genome in a way roughly equivalent to copying 2,000 thick textbooks on a word processor in eight hours. He pointed out the "incredible accuracy" of the replicative DNA polymerases, which make less than one mistake per 10 million letters. In their exercise copying a 500-word paragraph, the students' own error rates ranged from 0 to as high as one in 20.
Accuracy during DNA replication is critical to human health, Kunkel continued. Mistakes result in mutations. The consequences can be harmful, with increased risk of cancer, degenerative disease, infertility, reduced immunity and even death. In some cases, however, Kunkel said mutations can perform a beneficial role, such as increasing selective advantage in evolution or promoting the development of normal immunity.
Pointing out that there are sixteen different DNA polymerases in the human cell, Kunkel gave the students the opportunity to determine the accuracy of three different DNA polymerases themselves using a laboratory method he developed in the early 1980s known as the M13mp2 fidelity assay (http://www.ncbi.nlm.nih.gov/pubmed/3769876?ordinalpos=14&itool=EntrezSystem2.PEntrez.Pubmed.Pubmed_ResultsPanel.Pubmed_DefaultReportPanel.Pubmed_RVDocSum) . The assay uses a reporter lacZ gene in a DNA molecule copied by the test DNA polymerase. If the copy is accurate, the undisrupted gene will produce a blue bacteriophage plaque in a petri dish. If a polymerase error occurs, the resulting mutant will be evident in lighter blue and even colorless plaques.
The students used pressure-sensitive colony counters to count the number of mutated plaques, just as the members of the Kunkel laboratory do in their experiments. Kunkel said, "Research often gets down to the very mundane thing of counting M13 plaques on a petri dish and scoring for mutants."
According to Diane Klotz, Ph.D., interim director of the NIEHS Office of Fellows' Career Development, (http://inside-www.niehs.nih.gov/ofcd/) David Armstrong, Ph.D., head of the Membrane Signaling Group, suggested integrating active learning into the student seminars. Armstrong, who was an observer at the seminar, said he learned about active learning from a 2008 article (http://www.ncbi.nlm.nih.gov/pubmed/19039122?ordinalpos=2&itool=EntrezSystem2.PEntrez.Pubmed.Pubmed_ResultsPanel.Pubmed_DefaultReportPanel.Pubmed_RVDocSum) in Science and the 2007 book Scientific Teaching used in a program at the University of Wisconsin.
Klotz said she believes "the new format is working well and the events have piqued the interest of the summer interns." As one of the students at the seminar, John Peart, noted, "The exercises helped me remember" the concepts of the presentation.
(Laura Hall is a biologist in the NIEHS Laboratory of Pharmacology currently on detail as a writer for the Environmental Factor.)
Highlights of the 2009 Summers of Discovery Program at NIEHS
The forty-six high school, undergraduate, and graduate school students in the 2009 NIEHS Summer of Discovery Program explore environmental science in a cutting-edge research setting. The students' experiences include working on a research project with mentors, science seminars incorporating active learning, and workshops on career development. The students also receive instruction in the practical aspects of working in a research laboratory - lab and radiation safety, animal handling, and computer and presentation skills.
On May 27, Linda Birnbaum, Ph.D., director of NIEHS and the National Toxicology Program (NTP) kicked off the 2009 program with an introduction to environmental research on the "bad actors" - environmental chemicals that detrimentally affect human health. In addition to giving an overview of historical and emerging human health risks from chemical exposures, Birnbaum discussed some of her own toxicology research.
In a July 15 seminar, Dori Germolec, Ph.D., a biologist in the Toxicology Branch, talked about allergic disease, with a focus on skin hypersensitivity and how potential chemical sensitizers are tested. Germolec discussed the need for alternative test methods and the role of NTP and partner organizations. (http://ntp.niehs.nih.gov/pubhealth/evalatm/index.html) The students were asked to examine test data from four proposed alternate test methods and determine which ones they judged to be acceptable alternative methods.
On July 22, David Miller, Ph.D., principal investigator of the Intracellular Regulation Group, gave a seminar about how the body protects itself from many xenobiotic substances, including drugs, by way of the cytochrome P450 metabolizing enzymes (CYPs) and the ATP binding cassette efflux transporters, likening them to "chemists," "cops," and "bouncers." He explained how high xenobiotic concentrations could "overwhelm" the CYPs and transporters, leading to toxic drug-drug and drug-xenobiotic interactions. The students discussed possible causes of varying patient responses to therapeutic drugs in different scenarios.
The final seminar of the 2009 program on August 5 will be an introduction to epidemiology.