Effect of thyroid hormone concentration on the transcriptional response underlying induced metamorph

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Effect of thyroid hormone concentration on the
transcriptional response underlying induced
metamorphosis in the Mexican axolotl (Ambystoma)
Robert B. Page1, S. Randal Voss1, Amy K.
Samuels1, Jeramiah J. Smith1, Srikrishna Putta1,
and Christopher K. Beachy2
1Department of Biology and Spinal Cord and Brain
Injury Research Center, University of Kentucky
and 2Department of Biology and Amphibian Growth
Project, Minot State University
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Comparisons of standard metamorphic gene
expression and morphology profile with
endocrine-disrupted profile in salamander
Ambystoma mexicanum
Ambystoma mavortium (tigrinum)
metamorphosis
Paedomorphosis ( metamorphic failure)
5 nM TH
metamorphosis
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Basically..
Grow salamanders in experimental design
skin liver brain tail
Collect mRNA
cDNA
microarray
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28 days after immersion in 5 nM TH
epithelial membrane protein 1
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DESIGN
CONTROL
T4 IMMERSION
T4 IMMERSION
no TH
5 nM TH
50 nM TH
0 days
2 days
12 days
28 days
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15 DAYS POST- EXPOSURE
control
50 nM TH
5 nM TH
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ANALYSIS PART I UNIVARIATE ANALYSIS
A series (4844) of one-factor ANOVAs comparing
expression level among treatment groups (I.e., 0,
5, and 50 nM TH)
Linear and quadratic regression analyses
Used to identify genes for multivariate analysis
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Volcano Plot representing univariate analyses
4844
to 802 loci for consideration ( DEGs)
P 0.05
2X up or down expression relative to controls
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ANALYSIS PART II MULTIVARIATE ANALYSIS
Principal Components Analysis
Bioinformatic comparison to other microarray
databases metamorphosis in Xenopus
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day 28
day 12
day 2
day 0
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day 12
day 28
day 2
day 0
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day 28
day 12
day 28
day 12
day 2
day 2
day 0
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A phylogeny of model craniates that have a genome
project
WHY SALAMANDER?
--phylogenetic place
--natural history
--experimental possibilities and husbandry
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Bioinformatic Comparison with Xenopus
TH-skin
TH-intestine
(this study, 2008, BMC Genomics 978)
(Buccholz et al., 2007, Dev. Biol. 303576-590)
1997 DEGs
802 DEGs
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Finishing up -TH dose influence timing of
onset -Sets of transcription responses -Diversity
in expression To view microarray database,
visit -www.ambystoma.org