Marla Ann Fisher
of: Doctor of Philosophy
Department: Biological Sciences
Title: Health Impacts of Polychlorinated Biphenyls in Aquatic
Dr. Charles Ide, Chair
Dr. Rob Eversole
Dr. John Spitsbergen
Dr. Jay Means
Friday, March 12, 2004 1:30 pm - 3:30 pm
Polychlorinated biphenyls (PCBs) are a class of synthetic halogenated
aromatic hydrocarbons that are widely used in industry and manufacturing.
Due to their resistance to degradation and highly lipophilic nature,
PCBs persist in the environment and bioaccumulate in organisms, adversely
affecting a variety of health endpoints. I first tested for observable
health effects of PCBs in a laboratory model aquatic animal, Xenopus
laevis, exposed to PCBs dissolved in dimethylsulphoxide (DMSO) carrier-medium
from day 5 through day 9 postfertilization. Exposure to acute, high
concentrations of the PCB mixture Aroclor 1254 (10, 50 and 100 ppm)
caused statistically significant reductions in survival and body size.
In addition, I observed several histological indicators of health effects,
including aberrant tail tip, myotomal, and melanocyte morphologies.
I next tested for potential health effects of PCBs in carp (Cyprinus
carpio) from the Kalamazoo River Superfund site (MI, USA). Carp are
found throughout the Kalamazoo River and feed benthically in heavily
PCB-contaminated sediment. I utilized real time RT-PCR to examine mRNA
expression levels of multiple genes in hepatopancreas of carp from both
juvenile carp exposed to PCBs in the laboratory and from carp caught
from PCB contaminated and upstream control sites in the Kalamazoo River.
Significantly elevated levels of cytochrome P4501A1 (CYP1A1) mRNA was
found in PCB contaminated Kalamazoo River carp (t-test, t=0.0302) and
in carp fed PCBs in the laboratory (ANOVA, p=0.0012). However, no significant
changes were found in bioindicator oxidative stress genes (gamma-glutamyl
cystein synthetase and magnesium superoxide dismutase) and metabolic
genes (phosphoenolpyruvate carboxykinase and nucleolin) examined.
I further examined hepatopancras histopathology and ultrastructure in
Kalamazoo River carp. I found that carp from PCB contaminated sites
have an increased total area (ANOVA, p=0.0263) and number per area (ANOVA,
p=0.0453) of macrophage aggregates in hepatopancreas than carp from
control sites. Ultrastructural images show an increase in activated
phagolysosomes and phospholipid inclusions in macrophage aggregates,
suggesting alterations in lipid metabolism. This research indicates
that carp are responding to PCB exposure, and that chronically exposed
field carp show changes in liver cell disposition that may contribute
to health effects.
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