Environmental Factor, August 2010, National Institute of Environmental Health Sciences
Summer Students Flock to Lecture Series
By Negin Martin
The popularity of the first three Summers of Discovery (SOD) seminars in July proved that their new format was a formula for success (see story(http://www.niehs.nih.gov/news/newsletter/2010/august/spotlight-postdocs.cfm)). On average half or more of the 50 students participating in this year's summer program attended each of the seminars.
Heavy metals - a common health risk in the environment
Jennifer Sims, Ph.D., opened the SOD seminar series by explaining the outcome of exposure to high doses of heavy metals on human health. Due to their stability and persistence in the environment, arsenic, lead, and mercury are ranked among the most hazardous pollutants. In addition to natural sources, smelting of the ores, incorporation of metal coating in paint, and burning of fossil fuels have increased levels of accumulated metals in the environment, wildlife and humans.
Sims gave details of known toxicological responses to heavy metals and finished her talk by introducing C. elegans as a model organism for studying metal toxicity. Students examined assigned petri dishes of C. elegans with different metal exposure levels to determine the LD50s - the lethal dose that killed half of the population.
Pollution due to release of non-essential metal cadmium into the environment - from discarded old batteries and fossil fuel combustion - and its effect on gene regulation was the topic of the talk by Laura Fuhrman, Ph.D.
Graduate student Matthew McElwee introduced SOD interns to the microarray technology. For the last activity of the day, groups of students had to analyze microarray results to determine which genes are up- or down-regulated.
Radiation - protecting our genetic stability
NIEHS Radiation Safety Officer Bill Fitzgerald opened the second session of SOD presentations with an energetic and engaging talk about types and sources of radiation. Students learned about why some atoms radiate and what type of radiation is harmful to health. The first activity prompted students to list at least 10 sources of radiation and rank them based on their ionizing strength.
Mercedes Arana, Ph.D., and Danielle Watt, Ph.D., taught interns about the differences between DNA damage and DNA mutations. Environmental insults such as ionizing radiation can damage DNA, but cells are equipped with DNA repair mechanisms that protect genetic stability. During the process of repair, some damage is translated into modifications to the genome that are preserved and passed on to progenies as mutations. Presenters introduced students to the processes involved in DNA replication and repair in cells.
Students also got a chance to test the amount of protection that sunblocks, sunglasses, and clothing offer from cosmic radiation, as they went outdoors with radiation sensitive beads and analyzed the different ways of blocking UV light from sun.
Steroids and hormones: natural and unnatural sources of endocrine disruption
The first speaker for the third week of the SOD series was Abee Boyles, Ph.D. (http://www.niehs.nih.gov/research/atniehs/dntp/assoc/ohat/staff/boyles/), an epidemiologist who investigates the role of maternal folic acid levels in birth defects. Boyles outlined the debate over the healthy levels of folic acid. In the U.S., grains and cereals are fortified with folic acid to lower the rate of birth defects. However, some question the health effects of cumulative high levels of folate from dietary supplementation. Boyles presented parts of her ongoing research that demonstrate an association between lower levels of maternal folic acid and children with cleft lip and palate.
Endocrine disruptors in common household items was the topic of the second activity conducted by Sophie Bolick, Ph.D. Students learned about dioxins, phthalates, and bisphenol A in cosmetics and plastics. Archana Dhasarathy, Ph.D., and Erin Hopper, Ph.D., instructed students during an activity on how to measure and compare fat content of regular, fat-free, and baked snacks.
At the closing of the third session, students heard a talk by Wendy Jefferson Ph.D., about genestein, a phytoestrogen in soy. Phytoestrogens are naturally occurring plant steroids that mimic estrogen and have been shown to have a profound effect on the reproductive system. Infants on soy formulas are exposed to high doses of genestein, which raises concern. Jefferson's research on mice has shown that exposure to genestein has adult reproductive outcomes and increases the chance of uterine cancer.
(Negin Martin, Ph.D., is a biologist in the NIEHS Laboratory of Neurobiology Viral Vector Core Facility and a 2009 Science Communication Fellow with Environmental Health Sciences. She recently completed a postdoctoral fellowship with the NIEHS Membrane Signaling Group.)