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Research interests of our faculty encompass pathogenesis of cell injury, carcinogenesis, environmental and comparative pathology, molecular biology, immunology and aquaculture science. Ongoing research at the Aquatic Pathobiology Center focuses on aquatic toxicology, pathology, and aquatic animal models for human health and diseases.

Ongoing investigations involve the use of tissue explants and hepatic tissue slices to delineate phase I and phase II metabolic alterations due to exposure to environmental stressors. These stressors in the aquatic environment include PAHs, PCBs, metals, biotoxins and suboptimal water quality. Alterations in phase I (cytochrome P450-mediated) and phase II (conjugation) pathways are known to effect an organism's susceptibility to variety of xenobiotic stressors. Phase I-phase II metabolic studies are also conducted on Chesapeake Bay dwelling invertebrates to investigate whole organism metabolic alterations as an enpoint of environmental contaminant exposure. Chemical stressors include indirect-acting environmental carcinogens, other organics and metals. Alterations in biotransformation pathways and kinetics also effect xenobiotic uptake, distribution and elimination, as well as the metabolism of endogenous substrates.

The role of nutrient enrichment on the presence, growth and virulence of opportunistic fish pathogens is also under investigation. Additional studies help to define the role of water pollutants and dinoflagellate toxins on liver, gill, renal and behavioral toxicity. The Aquatic Pathobiology Center, in coordination with the UM Department of Medicine and the Center of Marine Biotechnology, supports the culture of Pfiesteria-like dinoflagellates, as well as dinoflagellate toxin assay development.

Fish are also serve as non-mammalian models in human pathology and toxicology. An important, long-term study, under the direction of Dr. Renate Reimschuessel (FDA Center for Veterinary Medicine), involves the response of the kidney to toxic injury. The fish kidney, unlike mammalian kidney, possesses the ability to replace injured nephrons with entirely new nephrons. The molecular basis of this response is being characterized with hopes of developing new treatments (other than dialysis or transplants) for chronic renal failure. Other studies include evaluation of immune function in fish exposed to environmental contaminants such as copper or to pathogens such as Mycobacterium marinum (fish tuberculusos). We are also investigating the pathogenesis of several species of Mycobacteria and developing diagnostic tests for these pathogens. Finally, we are conducting studies to develop new theraputic agents for pet fish and aquaculture species. Additional studies under the direction of Dr. Michele Trucksis (UMB Center for Vaccine Development) focus on gene therapy, using Mycobacteria and the goldfish model.

Studies under the direction of Dr. Benjamin Trump focus on myxosporean parasites of fish, specifically Myxosoma cerebralis, the causative agent of whirling disease. This disease affects salmonids and is of great importance both ecologically and economically in aquaculture.

Department of Pathology faculty conduct a wide variety of studies in conjunction with the U. S. Fish and Wildlife Service, the U.S. Environmental Protection Agency, the Maryland Department of Natural Resources, the Maryland Department of the Environment, the Maryland Department of Health and Mental Hygiene, Maryland Sea Grant, Northeastern Regional Aquaculture Center, the National Institutes of Health and the National Cancer Institute. Investigations are conducted to evaluate the impact of xenobiotics on fish from contaminated waterways, while other studies examine the effects of toxicants on experimentally treated animals.

Investigators study many different aquatic animals, including locally important species, such as striped bass and largemouth bass of the Chesapeake Bay. Click here to link to ongoing APC studies concerning fish health in the Chesapeake Bay.

Student Research Interests:

Students resident at the APC are enrolled in one of several graduate programs within the University of Maryland Systems. These programs include the System-wide Program in Toxicology, the Pathology Program, the Marine-Estuarine Environmental Sciences Program, the Animal Sciences Program.

Cynthia B. Stine
Ph.D. program in Marine-Estuarine Environmental Sciences

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Sara J. Pollack
Ph.D. program in Marine-Estuarine Environmental Sciences

Excretia from concentrated animal feeding operations (CAFOs) contain endogenous steroid hormones that remain stable and persistent in the environment. The cause for concern associated with these steroid hormones involves aquatic organisms, such as fish, that may experience chronic exposure to these endocrine distrupting mixtures in ponds, streams, lakes and rivers. The goal of my research is to analyze exposure effects of poultry litter leachate on the reproductive capacity of the fathead minnow.   Reproductive endpoints including homone biochemistry, fecundity, survivorship, gender determination and behavior will be analyzed to address the question of how exposure to the leachate affects the capability fathead minnows to reproduce successfully.

Jaime F. Gonzalez
Ph.D. program in Marine-Estuarine Environmental Sciences

Comparative phase I and phase II biotransformation reactions in aquacultured finfish species is being used to better understand species' similarities and differences in drug metabolism. Similarities in biotransformation profiles could help to establish "crop groupings" and subsequently facilitate the drug approval process for therapeutics in aquaculture. Albendazole, a broad spectrum antiparasitic, is being used as a model drug in my research to compare metabolic capabilities in aquacultured fish species.

Roberta Garcia
Ph.D. Program in Marine-Estuarine-Environmental Sciences

This research focuses on the effects of oxytetracycline on aquatic plants and algae. Antibiotics have been widely used to treat bacterial diseases in food animals and plants since the mid 1940s. Oxytetracycline is one of only two FDA-approved antibiotics for use in aquaculture.   Tetracyclines are believed to exert their bacteriostatic effect by binding to the 30S subunit of 70S ribosomes and inhibiting protein synthesis, yet they have also been found to alter protein synthesis in mammalian and plant cells.   Tetracyclines are excreted unchanged and enter the environment through feces and urine as biologically active compounds.   Since oxytetracycline is typically administered through medicated feed, the use of oxytetracycline in aquaculture is a direct source of contamination to the aquatic environment.   Very little research has been conducted regarding the amount and fate of oxytetracycline discharged from land-based aquaculture systems.   Varying concentrations of oxytetracycline may disrupt normal aquatic plant growth, development, and senescence in complex ways that have not been investigated in traditional toxicity assays.   Furthermore, agricultural research has shown that biologically active oxytetracycline is not only readily absorbed through plant tissue, but is also absorbed by insects that feed on the treated plants.   It is highly likely that other herbivores can absorb active drug, which may, in turn, influence their protein metabolism.   The recent discovery of pharmaceuticals in sewage, surface, ground and drinking water supplies, the general trend toward intensification of aquacultural production methods, and the rising interest in using aquacultural effluent waters to grow vegetables, spices, and algae for human and domestic animal consumption, indicates an urgent need for scientists to increase their understanding of the dynamics of oxytetracycline in aquatic environments.   This is a complex task, since oxytetracycline can form up to 64 different tautomers in solution, and only three of the known degradation products, anhydrotetracycline, epitetracycline, and epianhydrotetracycline, have been widely studied.   The purpose of this project is to determine the effects of chronic, low levels of oxytetracycline on two submerged aquatic plants and at least two species of algae that will be grown under controlled pH, temperature, and light environments.   Methodologies will include analysis of uptake by high performance liquid chromatography (HPLC) and microbial inhibition assays (paper disk and turbidity), spectrophotometric analyses of pigment changes, comparison of total protein content and changes in proteomic phenotype.

James D. Salierno
Ph.D. program in Marine-Estuarine Environmental Sciences (Graduated 2005)

The majority of fish species live in groups (shoals) or form organized schools at some point during their lives, and investigation of alterations in these behaviors can provide information regarding fluctuations in the environment. My research involves the quanitation of behavioral responses in groups of fish to various stressors, particularly harmful algal bloom events. Harmful algal bloom events have a deleterious effect on fish by releasing neurotoxins, irritating gill filaments, and reducing oxygen in aquatic habitats. I examine swimming paths of groups of Atlantic menhaden, Brevoortia tyrannus, and killifish, Fundulus heteroclitus (See movie) after they have been exposed to neurotoxins released by harmful algal bloom species. In addition, I am examining regions in the brain responsible for schooling and shoaling behavior to investigate neural changes from harmful algal bloom toxin exposure in an attempt to link changes in swimming behavior with alterations in brain function. Changes in swimming behavior in the laboratory may provide information on how schools and shoals of fish are affected by harmful algal bloom events in natural conditions.

Geoffrey Gipson
M.S. Program in Toxicology (Graduated 2004)

My area of interest is the behavioral response of fish to toxicological stressors. I examined the swimming paths of fish which have been exposed to various neurotoxins and comparing them to the paths of healthy fish. Variables which will be taken into account are total distance travelled, velocity, and angular changes. Through analysis of temporally randomized video segments, these variables were quantified via computer software which was developed at the Aquatic Pathobiology Center.

Cynthia B. Stine
M.S. Program in Marine-Estuarine-Environmental Sciences (Graduated 2003)

My research interests focus on tumorogenesis in fish. I will be looking into the activation of oncogenes and the inactivation of tumor suppressor genes in various fish organ systems. Literature searches indicate that tumors occur more frequently in cyprinds and salmonids, and tumors of the skin and peripheral nervous system are the most common. This work will utilize specimens in the Registry of Tumors in Lower Animals located in the Smithsonian Institution in Washington D.C. Stemming from my background in education, I will also work to create a database which will catalog the lesions in this Registry and make them readily available for future research.

Lisa E. Melewski
M.S. Program in Pathology (Graduated 2003)

Lisa's research focused upon the effects of endocrine disrupting compounds (EDCs) on aquatic organisms. The growing list of known and suspected EDCs contain a diverse group of chemicals such as pesticides (dieldrin, endosulfan, DDT and its metabolites, tributyltin, chlordane) and industrial chemicals (PCBs, phthalates and dioxins). These compounds are a growing concern for both humans and wildlife because of their ability to disrupt the normal functions of the endocrine system and their abundance in our environment. EDCs have been shown to cause morphological and physiological reproductive changes in exposed fish such as vitellogenesis and the presence of ovo-testes in males as well as the acquisition of male secondary sexual characteristics in females. We propose that during critical periods of development, exposure to EDCs disrupt the normal formation of sexually dimorphic regions of the teleost brain. Further, this disruption could result in altered reproductive physiology, morphology and behavior, and ultimately reproductive success. My research goal is to determine if sexual dimorphisms in neuronal dendritic spine densities exist in the hypothalamus of Fundulus heteroclitus (mummichog). If these differences do exist, then subsequent studies will be performed to determine if exposure to different EDCs will modify the sexual dimorphic regions of the brain in both adult fish and fish exposed during critical periods of central nervous system development.

Suzanne V. Jacobson
Ph.D. Program in Marine-Estuarine Environmental Science (Graduated 2003)

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Pedro Del Valle
Ph.D. Program in Toxicology (Graduated 2001)

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Adel M. Talaat
Ph.D. Program in Marine-Estuarine Environmental Science (Graduated 2001)

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