1. 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

2. 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

3. Basically….. skin liver brain tail Collect mRNA cDNA microarray
Grow salamanders in experimental design
skin
liver
brain
tail
Collect mRNA
cDNA
microarray

4. cDNA T

6. 28 days after immersion in 5 nM TH
epithelial membrane protein 1

7. DESIGN
CONTROL
T4 IMMERSION
T4 IMMERSION
no TH
5 nM TH
50 nM TH
0 days
2 days
12 days
28 days

8. 15 DAYS POST-
EXPOSURE
control
50 nM TH
5 nM TH

9. 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

10. Volcano Plot representing univariate analyses
4844 to
802 loci for
consideration
(= DEGs)
P = 0.05
2X up or down expression
relative to controls

11. MULTIVARIATE ANALYSIS
ANALYSIS PART II:
MULTIVARIATE ANALYSIS
Principal Components Analysis
Bioinformatic comparison to other microarray databases: metamorphosis in Xenopus

15. day 28
day 12
day 2
day 0

16. day 12
day 28
day 2
day 0

17. day 28
day 12
day 28
day 12
day 2
day 2
day 0

18. A phylogeny of model craniates that have a genome project
mouse
human
chick
Xenopus
axolotl
zebrafish
Mammalia
Amniota
Lissamphibia
Tetrapoda
Osteichthyes
A phylogeny of model craniates that have a genome project
WHY SALAMANDER?
--phylogenetic place
--natural history
--experimental
possibilities and
husbandry

19. Bioinformatic Comparison with Xenopus
TH-skin
(this study, 2008,
BMC Genomics 9:78)
TH-intestine
(Buccholz et al., 2007,
Dev. Biol. 303: )
802 DEGs
1997 DEGs
n = 111
EXPRESSION PATTERN
% of genes
Common
DEGs

20. To view microarray database, visit
Finishing up
-TH dose influence timing of onset
-Sets of transcription responses
-Diversity in expression
To view microarray database, visit -