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Effect of thyroid hormone concentration on the transcriptional response underlying induced metamorphosis in the Mexican axolotl ( Ambystoma ). Robert B. Page 1 , S. Randal Voss 1 , Amy K. Samuels 1 , Jeramiah J. Smith 1 , Srikrishna Putta 1 , and Christopher K. Beachy 2*.
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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
Comparisons of standard metamorphic gene expression and morphology profile with endocrine-disrupted profile in salamander Ambystoma mavortium (tigrinum) Ambystoma mexicanum metamorphosis Paedomorphosis (= metamorphic failure) + 5 nM TH metamorphosis
Basically….. Grow salamanders in experimental design skin liver brain tail Collect mRNA cDNA microarray
cDNA T T T T T T cDNA
28 days after immersion in 5 nM TH epithelial membrane protein 1
DESIGN CONTROL T4 IMMERSION T4 IMMERSION no TH 5 nM TH 50 nM TH 0 days 2 days 12 days 28 days
15 DAYS POST- EXPOSURE control 50 nM TH 5 nM TH
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
Volcano Plot representing univariate analyses 4844 to 802 loci for consideration (= DEGs) P = 0.05 2X up or down expression relative to controls
ANALYSIS PART II: MULTIVARIATE ANALYSIS Principal Components Analysis Bioinformatic comparison to other microarray databases: metamorphosis in Xenopus
day 28 day 12 day 2 day 0
day 12 day 28 day 2 day 0
day 28 day 12 day 28 day 12 day 2 day 2 day 0
Xenopus mouse zebrafish human axolotl chick Mammalia Lissamphibia Amniota Tetrapoda Osteichthyes A phylogeny of model craniates that have a genome project WHY SALAMANDER? --phylogenetic place --natural history --experimental possibilities and husbandry
n = 111 Common DEGs % of genes EXPRESSION PATTERN Bioinformatic Comparison with Xenopus TH-skin (this study, 2008, BMC Genomics 9:78) TH-intestine (Buccholz et al., 2007, Dev. Biol. 303:576-590) 802 DEGs 1997 DEGs
Finishing up -TH dose influence timing of onset -Sets of transcription responses -Diversity in expression To view microarray database, visit -www.ambystoma.org