The following is the first in a series of occasional articles on research being done at UWM's Marine and Freshwater Biomedical Sciences Center (MFBSC), one of four aquatic research centers funded by the National Institute for Environmental Health Studies (NIEHS). The center, housed at the WATER Institute, includes environmental health research using aquatic models.
UWM Researcher Probes Unknown Health Effects of Drugs in Aquatic Environments
By Laura L. Hunt
Rebecca Klaper and daphnia, a small crustacean near the bottom
of the Great Lakes food chain.
Photo by Pete Amland
While most toxicologists investigate the effects of substances known or suspected to be harmful to living things, Rebecca Klaper studies the effects of what she calls "emerging contaminants," compounds that have only recently been introduced into the environment.
"Until now, no one has measured their effects," says Klaper, Shaw Assistant Scientist with UWM's Marine and Freshwater Biomedical Science Center (MFBSC).
In her laboratory at the Great Lakes WATER Institute, Klaper uses genomics, in addition to more traditional forms of analysis, to find out whether substances such as pharmaceuticals are a threat to human health.
Using fathead minnows as her model organism, Klaper tracks the "expression" of individual genes, comparing how they are "activated" in a minnow that is exposed to a drug and one that is not. It's on this genetic level that scientists hope to identify specific genes that influence sensitivity and/or resistance to environmentally-relevant chemicals.
If she finds harmful effects in fish exposed to the drugs, then it could be a warning that the contaminant also poses a threat to humans. Klaper uses an aquatic model because of the many advantages: The genome of fish is similar to that of humans and both are highly sensitive to environmental contaminants.
"Genomics is a fine-scale way of finding a problem," she says. "It identifies the thing that is bothering the organism in its environment before the whole ecological community is disrupted."
Once excreted from the body, some prescription drugs are removed by sewage treatment. But others pass through treatment plants unaltered and end up in the lake or other drinking water supplies. Cholesterol-controlling drugs known as lipid regulators, for example, are one kind that has been found in drinking water. So have certain pain relievers and the antidepressant Prozac.
Already she has identified several potentially harmful effects from exposure to drugs in drinking water simply by testing the visual health of minnows after exposure.
In one of her initial experiments, she exposed the fish to a miniscule amount of a lipid regulator – one part per billion, a concentration that has been detected in Lake Ontario. By the next morning, the minnows were dying. "That's a pretty dramatic result," she says.
It's research that has recently appeared in newspapers across the country, from The Washington Post to the Seattle Times.
But the mere presence of a potential toxin, especially during its early development, is usually not enough to draw a conclusion about its effects.
For example, Klaper also is investigating whether exposure to the drug Prozac has any effect on the development of minnow embryos. An embryo may not look any different after exposure, but the gene expression can reveal development-altering effects that lead to illness later in life.
"At low, low levels, we want to know what the effect is on the fish at different stages of their life," she says, "not only physical changes, but also genomic. Are their gene expressions changing?"
She and her students also are studying the effect of pharmaceutical compounds on Daphnia, a tiny shrimp-like creature that serves as a primary food source for small fish in Lake Michigan.
Besides prescription drugs, Klaper conducts research on the effects of methyl mercury, a byproduct of coal-burning power plants that bio-accumulates in fish. Her studies aim to determine the effects in humans who eat the fish. Again, the problem is that scientists don't know yet the long-term health effects of methyl mercury.
To predict those, and to find information that will help people prevent illness, scientists at UWM's MSBSC are connecting the dots, says Director David Petering. "We want to link what's happening to the behavior of the organism with changes in its environment, and also to note alterations at the genetic level. Then we can work from both end points toward the middle."
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