The Toxicologist - Society of Toxicology

does not compromise neonatal survival and postnatal growth as seen with PFOS
and PFOA, while the hepatic effects appear to be similar among these chemicals.
This abstract does not necessarily reflect U.S. EPA policy.
1626 IDENTIFICATION OF Wnt AND Rspo GENES WHOSE
EXPRESSION PATTERNS IN FETAL MOUSE
UROGENITAL SINUS (UGS) ARE ALTERED BY 2, 3, 7, 8-
TETRACHLORODIBENZO- p -DIOXIN (TCDD).
R. W. Moore 1 , L. L. Abler 2 , V. Mehta 2 , C. M. Vezina 2 and R. E. Peterson 1 .
1 School of Pharmacy, University of Wisconsin, Madison, WI and 2 Comparative
Biosciences, University of Wisconsin, Madison, WI.
Wnt genes regulate tissue patterning, cell fate, and proliferation during embryogenesis,
but little is known about their role in UGS and prostate development. Our lab
is testing the hypothesis that in utero TCDD exposure alters prostatic budding patterns
and reduces prostatic bud number by dysregulating Wnt signaling. Specific
objectives were to determine the expression patterns in control UGSs of the 19
known mouse Wnt genes, and to determine if TCDD changes these patterns.
Because canonical Wnt signaling is also activated by R-spondins, expression of the
four Rspo genes was also examined. Pregnant C57BL/6J mice were dosed with
TCDD (5 μg/kg, po) or vehicle on e15.5, and UGSs were collected 24 hr later.
Gene expression patterns were determined by in situ hybridization on sagittal UGS
sections. Expression of Wnt1, Wnt3, Wnt8a, Wnt8b, and Wnt10b was very low or
absent in both vehicle- and TCDD-exposed UGSs. Wnt2a, Wnt2b, Wnt3a, Wnt4,
Wnt5a, Wnt5b, Wnt6, Wnt7a, Wnt9a, Wnt9b, Wnt11, Rspo1, Rspo3, and Rspo4 were
expressed in diverse patterns, but TCDD had little if any effect on any of these patterns
or their expression intensities. TCDD had no detectable effect on where
Wnt7b was expressed (throughout the epithelium except in basal urothelium), but
it appeared to increase expression intensity. Expression of Wnt10a was generally
confined to the basal epithelium, but TCDD exposure enhanced this expression in
the ventral prostatic budding region (where budding inhibition is greatest). Wnt16
was expressed primarily in pelvic urethral mesenchyme in control UGSs, but
TCDD extended its expression into the ventral UGS mesenchyme. TCDD reduced
Rspo2 expression in ventral UGS mesenchyme. Future research will investigate
whether altered expression of these four genes contributes to the prostatic budding
abnormalities caused by TCDD. (Supported by NIH grants ES01332 and
DK083425.)
1627 ZEBRAFISH EMBRYOS SEQUESTER
PETROCHEMICAL COMBUSTION PRODUCTS IN
LIPID DROPLETS, WITH UP-REGULATION OF
BIOTRANSFORMATION, OXIDATIVE STRESS, AND
INFLAMMATION-RELATED GENES.
R. Xiao, A. Bui, K. Kleinow and A. Penn. Louisiana State University School of
Veterinary Medicine, Baton Rouge, LA.
Rationale: Numerous fluorescent polynuclear aromatic hydrocarbons (PAHs) are
adsorbed onto the surface of nanoparticles produced during incomplete combustion
of petrochemicals. Incomplete combustion of the high volume petrochemical
1,3-butadiene (BD) yields PAH-rich soot (BDS) nanoparticles. Inhalation of these
particles results in up-regulation of biotransformation, oxidative stress and inflammatory
genes in mouse lungs. The zebrafish (ZF) embryo is a well-established
model for vertebrate development and is sensitive to exposure to a range of environmental
toxicants. We use ZF embryos to examine cell/molecular responses to
PAHs early in development. ZF embryos exposed to BDS nanoparticles fluoresce
and exhibit developmental abnormalities. Our goals here were to a) determine
where the PAH fluorescence is localized in ZF embryos and b) assess patterns of
embryo gene expression responses to BDS exposure. Methods: We exposed ZF embryos
to BDS nanoparticles (0,6,60 microg/ml) 24-72 hr. post-fertilization. We assessed
images, singly and merged, of Nile Red and BDS fluorescence; performed trranscriptome
analysis of pooled embryos (Affymetrix ZF Arrays; Expression
Analysis; Ingenuity Pathways Analysis); and confirmed results by qRT-PCR.
Results: We found 49 unique genes with absolute fold-change >1.5X in both of the
treated vs control group comparisons. Those genes were displayed on a heatmap
(R/Bioconductor) and cross-tabulated by biofunction (Ingenuity). Nile Red and
PAH fluorescence co-localized in lipid droplets. PAH fluorescence and up-regulation
of ZF genes homologous to human biotransformation, oxidative stress and
acute phase response genes proceeded in a dose-dependent manner. Conclusion:
ZF embryos reprise a number of mammalian responses to petrochemical combustion-derived
PAHs. ZF embryos may be valuable for assessment of developmental
responses to PAHs arising from combustion-based remediation of the BP Horizon
oil spill.
350 SOT 2011 ANNUAL MEETING
1628 PRENATAL TCDD AND POSTNATAL AUTOIMMUNE
DISEASE: A COMPARISON OF TWO MURINE STRAINS.
S. D. Holladay, A. Mustafa and R. M. Gogal. Department of Anatomy and
Radiology, University of Georgia, Athens, GA.
Pregnant female C57BL/6 and SNF1 mice were exposed to a mid-gestation dose of
2,3,7,8-tetrachlrordibenzo-p-dioxin (TCDD) and the offspring evaluated at adulthood.
The C57BL/6 mouse, a non autoimmune-prone strain, has a high-affinity
aryl hydrocarbon receptor (AhR) making it sensitive to TCDD where as, the SNF1
mouse has a low-affinity AhR and spontaneously develops autoimmunenephritis.
At 24 weeks, prenatal TCDD-exposed C57BL/6 mice had increased autoreactive
Vβ+CD4+17a and Vβ+CD3+ T cells biased toward the females. Cytokine levels
fluctuated during aging yet IFN-γ was elevated in the females, while IL-10 was elevated
in males at 48 weeks. In these prenatal TCDD C57BL/6 mice, B-lineage cells
were altered in the bone marrow and spleen, and circulating autoantibodies were
increased. In these same mice, there was significant anti-IgG and anti-C3 renal deposition,
suggesting an early stage of autoimmune lupus. The prenatal TCDD SNF1
offspring similarly showed increased peripheral Vβ+ cells and increased IFN-γ production
in the females plus increased autoantibody production in both sexes.
Likewise, male prenatal TCDD SNF1 mice had increased anti-IgG and anti-C3
deposition in kidneys suggesting an earlier onset of lupus. Both mouse models
therefore showed clear signatures of enhanced autoimmunity and autoimmune disease
after prenatal TCDD.
1629 EFFECT OF LOW-DOSE MERCURIC CHLORIDE
EXPOSURE ON EARLY ZEBRAFISH EMBRYO
DEVELOPMENT.
L. C. Abbott 1 , E. A. Moussa 2 and S. A. Hassan 3 . 1 Integrative Biosciences, Texas
A&M University, College Station, TX, 2 Anatomy and Embryology, Suez Canal
University, Ismailia, Egypt and 3 Anatomy and Embryology, Suez Canal University,
Ismailia, Egypt.
Much attention has focused on environmental contamination by heavy metals, pesticides,
and polychlorinated biphenyls. Mercury has been reported as a ubiquitous
environmental pollutant that is able to accumulate in the aquatic food chain with
severe risk for animal and human health. Zebrafish (Danio rerio) provide an excellent
vertebrate animal model system to study mechanisms of toxicity. Starting at 6
h post fertilization, zebrafish embryos were exposed for 42 hours to different concentrations
of mercuric chloride (HgCl): 0 [negative control], 100, 200, 300 and
400, 500, 1000 and 1500 ppb. Zebrafish embryos exposed to 2% ethanol served as
positive controls (100% embryonic death). Embryos were assessed at 48h post fertilization
for progress in development, morphometry and morphological deformities
of the trunk musculature. Immunohistochemical staining of muscle using antibody
to myosin was carried out on 5 micron thick sections of zebrafish embryos
that were fixed with 4% paraformaldehyde and embedded in paraffin. Embryos exposed
to 100 ppb HgCl revealed abnormal myosin staining (irregular diameter of
muscle segments and decreased intensity of myosin staining) compared to control
zebrafish embryos. Zebrafish embryos exposed to 200 and 300 ppb HgCl presented
irregularly stained bands of trunk musculature. Embryos exposed to 400 ppb HgCl
showed no staining for myosin indicating a significant delay in development of
myosin expression. Trunk and tail muscle fibers from additional paraffin sections
from zebrafish embryos exposed to 100 through 400 ppb HgCl were stained with
eosin and analyzed for morphologic parameters, including muscle fiber length and
degree of waviness. In general, abnormalities increased with increased exposure to
HgCl. These data indicate that even low dose exposure to HgCL can delay or alter
normal development of trunk musculature in exposed zebrafish embryos.
Support in part: The Arab Fund Fellowships Program.
1630 DEVELOPMENTAL TOXICITY OF THE HMG-COA
REDUCTASE INHIBITOR (PPD10558) IN RATS AND
RABBITS.
A. S. Faqi 1 , D. Prohaska 2 , R. Lopez 2 and G. McIntyre 2 . 1 Drug Safety Evaluation,
MPI Research, Mattawan, MI and 2 Drug Safety Evaluation, Furiex Pharmaceuticals,
Morrisville, NC.
PPD10558 is an orally active, lipid-lowering 3 hydroxy-3-methylglutaryl coenzyme
A (HMG CoA) reductase inhibitor (Statin) being developed as an anti-cholesterol
drug. We have studied the potential developmental toxicity effects of PPD10558 in
pregnant rats and rabbits given daily oral doses during the period of organogenesis.
Rats were dosed with 0, 20, 80 or 320 mg/kg/day from GD 6 to 17 and rabbits received
dose levels of 0, 12.5, 25 or 50 mg/kg/day from GD 6 to 18. Additional
groups in both studies served as TK animals and received the vehicle or PPD10558
in the same manner as the main study groups at the same dose levels. Blood samples