At the junction of two scientific disciplines, environmental toxicology and molecular biology, Dr. Ornella Selmin is investigating exactly why certain toxins damage organisms and what we might be able to do about it. Ornella’s focus is a chemical called Trichloroethylene or TCE, which is found everywhere! Since the middle of the last century it has been used as an industrial solvent and degreaser. It is used as a solvent in the dry-cleaning industry and is present in many of the products used daily in homes and in workplaces. Not surprisingly, TCE has found its way into the environment. Because of its volatility, its ability to shift from liquid to gaseous phase, TCE can pass from one solvent to another easily, contaminating the ground, air and water. This man-made chemical is a major contaminant at all of the US Environmental Protection Agency’s known sites of abandoned hazardous wastes or “superfund sites” (for more information see their website: www.epa.gov/superfund). More surprisingly, TCE has also been detected in pristine water springs.

Concentrations of TCE in the range 1 – 1000 parts per million (ppm) are known to cause liver cancer and kidney disease in animal studies. As a guide to understanding this concentration, consider the following: there are about 600 ppm of salt in the milk you had for breakfast, the chlorine in your pool probably has about 10 ppm and a smelly fart in your classroom has less than 0.05 ppm. Fortunately exposure to these levels of TCE usually only occurs in the workplaces where TCE is used and can be avoided with the proper safety procedures. However, the effects of exposure to TCE at doses one thousand times lower (1 – 1000 parts per billion), which members of the general public might find around their homes or in their drinking water, are not clear. Epidemiology studies from Tucson, Arizona and the Camp Lejeune Marine Corps base in North Carolina have shown a correlation between TCE in drinking water and high rates of births with heart defects. On observing these problems Ornella decided to bring her skills as a molecular biologist to bear on this problem.

In her laboratory in the Department of Veterinary Science and Microbiology, Ornella is using a technique called micro-array analysis to get a series of snapshots showing how much each gene is working in the developing heart. Using this technique Ornella can sift out those genes that are affected by TCE and its metabolites. She will do this by providing some pregnant rats with drinking water laced with TCE, while giving control rats pure drinking water. Dissecting the developing hearts from rat pups will enable Ornella to purify a class of chemicals called messenger-ribonucleic acids or mRNA, from the tissue. The collection of mRNA molecules is a representation of the amount and type of each and every gene that is being expressed in the developing heart. Using robots to perform repetitive tasks, Ornella will be able to measure the amount of each type of mRNA molecule as the heart develops. The thousands of graphs she will produce, showing how much each gene is producing mRNA while the heart develops, will allow her to paint a picture of which genes are important at particular stages of heart development and which of those genes are affected by the presence of TCE.

Ornella believes these experiments are important because an understanding of the cause of the embryonic malformations will point her in the direction of a cure. By understanding the genes that are required to make a heart and how they are affected by TCE and its metabolites, Ornella will be able to pinpoint the most effective points of intervention.

Because TCE is such an ubiquitous pollutant, avoiding exposure to low levels of the toxin may be difficult or expensive for certain communities, but an understanding of how we can best live with this pollutant may help to save lives.