The Toxicologist - Society of Toxicology

functionality of photosystem II and an increase on lipid peroxidation were detected.
Furthermore, the study of thermoluminescence emissions is a useful technique
to study the effects of environmental chemicals on photosynthetic organisms.
2386 TISSUE DISTRIBUTION OF MERCURY IN ALASKA
SCULPIN SPECIES.
S. Bhojwani, C. Lieske and T. O’Hara. University of Alaska Fairbanks,
Fairbanks, AK.
Mercury contamination of marine species is a big concern for subsistence hunters as
well as fish consumers today. Mercury accumulates in marine animals and is associated
with many negative health impacts including neurotoxicity. For this study, select
tissue samples from nineteen subsistence-caught sculpin species were taken,
freeze dried, and analyzed for total mercury (THg) via a DMA-80 (Direct Mercury
Analyzer-80) in order to determine the differences in mercury within and across
different tissue types (liver, muscle, heart and kidney). Additionally, differences in
mercury deposition within skeletal muscles were assessed. Wet weight THg concentrations
ranged from 0.58 to 0.935 ppm in the skeletal muscle, 0.015 to 0.39 ppm
in the liver, 0.017 to 0.24 ppm in the kidney, and from 0.016 to 0.17 ppm in the
heart. It was noted that as fish size increased, the THg present in the fish likewise
increased. Significant differences were noted between internal organs and muscle
tissue, with THg concentrations in muscle greater than THg in the internal organs
(liver, heart and kidney). A significant difference between the mean mercury content
across the four muscle samples was detected, with the mean mercury at the
caudal end greater than the mean mercury at the most cranial end for 18 of 19 fish.
However, the observed difference may not be biologically significant due to the heterogeneity
of the muscle samples. These data suggest that the internal organs of
these sculpin species have much less mercury content in comparison to the muscle
tissue, and that fish that are small or of average size may be safer to consume than
those of larger sizes.
2387 PROTEOMIC ANALYSIS OF A MODEL FISH SPECIES
EXPOSED TO INDIVIDUAL PESTICIDES AND A
BINARY MIXTURE.
A. D. Biales, D. C. Bencic, K. Blocksom, D. L. Lattier, R. Flick and L. Jim.
ORD NERL, U.S. EPA, Cincinnati, OH. Sponsor: H. Choudhury.
Pesticides are nearly ubiquitous in surface waters of the United States, where they
often are found as mixtures. The molecular mechanisms underlying the toxic effects
of sub-lethal exposure to pesticides as both individual and mixtures are unclear. The
current work aims to identify and compare differentially expressed proteins in
brains of male fathead minnows (Pimephales promelas) exposed for 72 h to permethrin
(7.5 μg/L), terbufos (57.5 μg/L) and a binary mixture of both. Twenty-four
proteins were found to be differentially expressed among all three treatments relative
to the control using an ANOVA followed by a Dunnett’s post-hoc test (p ≤
0.05). One protein was found to be differentially expressed among all treatment
groups and one protein was in common between the terbufos and the mixture
group. Fifteen spots were successfully sequenced using LC-MS/MS sequencing.
Proteins associated with the ubiquitin-proteasome system, glycolysis, the cytoskeleton
and hypoxia were enriched. As a second objective, we attempted to establish
protein expression signatures (PES) for individual permethrin and terbufos exposures.
We were unable to generate a useable PES for terbufos; however, the permethrin
PES was able to distinguish between control and permethrin-exposed individuals
in an independent experiment with an accuracy of 87.5%. This PES also
accurately classified permethrin exposed individuals when the exposure occurred as
part of a mixture. The identification of proteins differentially expressed as a result of
pesticide exposure represent a step forward in the understanding of mechanisms of
toxicity of permethrin and terbufos. They also allow a comparison of molecular responses
of the binary mixture to single exposures. The permethrin PES is the first
step in establishing a method to determine exposures in real-world scenarios.
2388 TRIBUTYLTIN (TBT), AN ENDOCRINE DISRUPTOR IN
ZEBRAFISH.
C. L. McGinnis and J. F. Crivello. Physiology and Neurobiology, University of
Connecticut, Storrs, CT.
Tributyltin (TBT) is an antifouling agent that has been implicated in the masculinization
of fish species worldwide; however, its masculinizing mechanism is not fully
understood. We have examined the actions of TBT as an endocrine disruptor on
three different endpoints in zebrafish (Danio rerio): 1) directly on nuclear receptors
in HeLa cells, 2) on enzymatic activities of hepatic acylated and sulfated testosterone,
and 3) on the expression of androgenic and estrogenic developmental markers
in vivo. Zebrafish estrogen receptor (zfERα, zfERβ1 and zfERβ2) dependent
activity was inhibited by TBT in a dose dependent manner, with an ED50 between
5nM and 50nM. TBT had no effect on zebrafish androgen receptor (zfAR); however,
TBT inhibited zebrafish aromatase (zfCYP19b-luc) dependent activity in a
dose dependent manner. In HeLa cells, TBT elicited a dose dependent activation of
the peroxisome proliferator-activated receptor gamma (PPARγ) and retinoid X receptor
alpha (RXRα) heterodimer, mediated through RXRα. In zebrafish exposed
to 1 to 5mg/kg TBT, there was increased liver sulfotransferase activity and decreased
acyl-CoA testosterone acyltransferase activity. Real-time PCR analysis of
sexual differentiation markers in zebrafish exposed to TBT revealed tissue-specific
responses. TBT overall has a masculinizing effect, but the masculinizing effect may
be tempered by the metabolism of TBT to dibutyltin (DBT).
2389 THE EFFECTS OF COPPER PYRITHIONE ON
DEVELOPING ZEBRAFISH EMBRYOS.
K. M. Almond and L. D. Trombetta. Pharmaceutical Sciences, St. John’s University,
Queens, NY.
Copper pyrithione, an active component in antifouling biocides predominantly
found in marine paints, has been shown to cause anomalies during early development
of mummichogs (Fundulus heteroclitus). Since a strict regulatory use of
organotins as antifouling agents has been imposed, a frequent substitute by foreign
markets has been the use of metal pyrithiones, principally zinc and copper.
Zebrafish (Danio rerio) embryos were exposed within the first hour after fertilization
to increasing concentrations of copper pyrithione (2, 4, 8, 12, 16, 32 and 64
μg/l) for 24 hours. Morphological abnormalities at 30, 60, and 120 hours post fertilization
were recorded. Hatchability was measured at every 12 hours for 5 days.
Following the 24 hour exposure, results show morphological abnormalities, particularly
of the notochord at concentrations of 12 μg/l and higher. The notochord was
severely twisted and abnormally segmented as the concentrations increased.
Distortions of the notochord began in the tail at the lower concentrations and proceeded
rostrally as doses increased. Edema was observed in the cardiac and yolk sac
regions at 12 and 16 μg/l concentrations. Hatching rate decreased in a dose dependent
manner. At 120 hours post fertilization, 47 percent of embryos hatched,
while all of the controls hatched by 96 hours post fertilization. Copper pyrithione
has shown to be toxic to zebrafish at concentrations of 12 μg/l and higher. The abnormalities
and deformities observed in fish larvae would significantly decrease
their chance of survival in non-controlled environments.
2390 TISSUE SPECIFIC EXPRESSION OF ORGANIC ANION
TRANSPORTING POLYPEPTIDES IN NATIVE FISH
SPECIES.
K. Steiner 1 , K. Shigehiro 2 , A. Meyer 2 and D. R. Dietrich 1 . 1 Human &
Environmental Toxicology, University of Konstanz, Konstanz, Germany and 2 Zoology
and Evolutionary Biology, University of Konstanz, Konstanz, BW, Germany.
Microcystins (MCs) are naturally occurring toxins that are produced by many
species of cyanobacteria. MCs are cyclic heptapeptide cyanotoxins with >80 structural
variants and a molecular weight ranging from 900 to 1100 Da. Toxic
cyanobacterial blooms in aquatic ecosystems have been associated with dramatic
changes in species distribution. It is hypothesized that the bioavailability of MCs,
via specific MC transporting organic anion transporting polypeptides (Oatps), governs
the susceptibility of different species and life-stages and thus the downstream
adverse effects on organisms and ecosystems more strongly than the level of MC
concentrations alone in the ambient environment. Consequently the presence of
Oatps and their organ specific expression in fish may be key to understanding the
biological effects of MCs. Recently verified short Oatps from native fish species
were sequenced using RACE PCR and phylogenetically analyzed in order to identify
specific Oatp subtypes, which were used for designing gene specific primers.
The improved primers were employed to analyze the Oatp subtype expression profile
in different fish tissues via real-time quantitative PCR. The different sequences
obtained were verified as Oatp by BLAST and elongated using RACE PCR. A sequence
identified as Oatp1d1 was expressed in a tissue-dependent manner, suggesting
an organ-specific transport of MC.
2391 INTERACTIVE EFFECTS OF BENZO(α)PYRENE,
BENZALKONIUM CHLORIDE, AND SEWAGE
EFFLUENT ON MEDAKA EMBRYOS.
A. McElroy and J. Gondek. School of Marine and Atmospheric Sciences, Stony Brook
University, Stony Brook, NY. Sponsor: R. Di Giulio.
Chemical mixtures represent a common stressor to organisms, yet traditional toxicological
approaches rarely examine interactive effects of contaminants found in the
environment. For aquatic organisms, particularly those living in urban watersheds,
exposure to mixtures from sewage inputs, surface run-off, and contaminated sediments
is a chronic problem. We evaluated the individual and combined effects of
SOT 2011 ANNUAL MEETING 513