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  Our Research    



Research at the Aquatic Toxicology Laboratory is focused on issues that relate to toxicology, physiology and human health.
  • On a toxicological level, we are interested in agricultural runoff, particularly as it pertains to runoff from rowcrop agricultural fields, and from beef cattle feedlot operations. We are also interested in sediments and the sorption and desorption of contaminants onto sediment particles.

  • On a physiological level, we are interested in gene expression and the use of differential gene expression as an endpoint of analysis in toxicological studies. We are also interested in relationships between gene expression and whole body performance, particularly as it pertains to reproduction.

  • From the perspective of human health, we are interested in the linkages between land use and water quality, and between water quality and human health outcomes. We use caged fish as bioenvironmental, sentinel organisms in our efforts to link these different areas of research.

We often look for student help with research efforts, so visit our students page to learn more about our current students. If you are interested, please contact me via email at: and set up an appointment.

What We Do
Our research involves both laboratory and field research across the state of Nebraska. Visit our What We Do page to learn more about what we do and to see photos of our research.

Current Projects
Here's a brief list of the current research projects we're working on:
  • The ATL is involved in exploration of the differential expression of the StAR mRNA in the fathead minnow with respect to the liver, kidney, gonad, and brain. Observation of effects fom exposure to the exogenous steroid hormone Trenbolone in the each of these tissues.

  • The ATL is evaluating the role sediments play in the fate, transport, and bioavailability of agricultural hormones. Exogenous hormones excreted by livestock are showing up in extracts of aquatic sediments. However, inconsistent gene expression currently being observed in fish is not fully understood. Previous lab experiments have shown that these compounds have fairly short half-lives. In the field, a degree of recalcitrant persistence is being found that is unexpected based on these studies. Interactions with sediment is hypothesized to affect the bioavailability of these compounds.

  • The ATL has developed a procedure for the esophageal ligation of the fathead minnow.  The purpose of this procedure is to provide insight into the route of uptake of steroidogenic compounds in exposed fish.  This study will be conducted in conjunction with exposure studies that analyze the effects of fish exposed to sediments spiked with steroidogenic compounds.  The ligation of the fathead minnow serves to prevent the ingestion of sediment in order to discover the extent of the role that ingestion plays in the exposure to steroidogenic compounds and its subsequent effects on gene expression.

Our Laboratory
Dr. Kolok’s 1150 sq. ft. laboratory is in Allwine Hall, the Biology building at the University of Nebraska at Omaha. To learn more about our laboratory facilities and see photos, visit our Laboratory page.

photo of laboratory students with Dr. Kolok

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