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Dr. Marlo Jeffries

Marlo Jeffries 2014
Associate Professor Direct: 817.257.6171
BS University of Nebraska at Omaha MS University of Nebraska at Omaha, 2005 Ph.D. University of Nebraska Medical Center, 2010
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Research Interests

As an environmental toxicologist, I am interested in the impacts of environmentally-relevant contaminants on various physiological processes, especially those related to endocrine function, reproduction, development and immunity.  As a physiologist, I am particularly interested in the interactions between reproductive hormones and immune function. My laboratory is currently pursuing four lines of research as described below.

1)      Development of the fathead minnow and sheepshead minnow as model organisms for immunotoxicity testing.  Contaminants present in the environment may pose a threat to the health of aquatic organisms by altering the function of their immune systems leading to increased disease vulnerability. My lab is currently developing two species of fish as model organisms for immunotoxicity testing in an effort to identify endpoints that can be utilized to determine the impacts of aquatic contaminants on immune system function.  2)      Determining the impacts of contaminants of emerging concerning (CECs) on endocrine and immune function in aquatic organisms. CECs are chemicals that are being detected in the environment at unexpected levels and that are not subject to regulatory standards.  The United States EPA recognizes several classes of compounds as CECs including pharmaceuticals, perfluorinated compounds (a component of non-stick surfaces) and polybrominated compounds (flame retardants added to a wide variety of consumer goods).  Students in my laboratory are currently investigating the impacts of exposures to polybrominated compounds on thyroid hormone signaling, reproductive endocrine function and immunity in fish and amphibians.

3)      Developing alternative methods for routine toxicity assessments. Routine toxicity tests used to determine the impacts of chemicals and effluents on aquatic organisms frequently utilize fish.  My laboratory is working to develop alternative toxicity testing strategies that ensure adequate and robust assessment of chemical and effluent safety, while simultaneously reducing or eliminating the number of animals used.

4)      Testing the immunocompetence handicap hypothesis. The immunocompetence handicap hypothesis (ICHH) asserts that androgens benefit males by increasing their expression of secondary sexual characteristics, but also harm males by suppressing their immune system.  We are currently testing the ICHH by examining the relationship between sexual ornamentation, reproductive hormones, stress hormones and pathogen resistance in male fathead minnows.

If you are interested in pursuing graduate or undergraduate research related to these lines of inquiry, please contact me.

Visit my lab website here:

Teaching Responsibilities

My primary teaching responsibilities for the fall semester are Mammalian Physiology (BIOL 40403, a 3 credit hour lecture course) and Principles of Toxicology (BIOL40453, a 3 credit hour readings/discussion course).  In the spring semester, I teach Vertebrate Endocrinology (BIOL 40473, a 3 credit hour lecture and laboratory course with a writing emphasis component).