Pam Clarkson

Effects of atrazine on thyroid hormone induction of metamorphosis in the axolotl (Ambystoma mexicanum)

Xenopus laevis Hayes et al, 2002, PNAS

-- Post application (Spring) runoff can be > 20 ppb

-- typical surface and groundwater concentrations at other times during other times of the year, 0.001 to 1.0 ppb

-- 3 ppb EPA standard for drinking water

ATRAZINE

ENDOCRINE DISRUPTION

Males exposed to 0.1 ppb have lowered testosterone, elevated estrogen, and intersex gonads

Introduction• Thyroid hormones induce metamorphosis

in the axolotl• We investigate affects of atrazine on TH-

induction of metamorphosis in the axolotl• We investigate affects of atrazine on

growth

Big PictureTo begin characterization of gene expression

during salamander metamorphosisHypothesis: no variation in gene expression during metamorphosis

For comparison to endocrine disrupted

metamorphosis

To identify loci that will be useful in field diagnostics of normal and endocrine disrupted metamorphosis

To correlate patterns of gene expression with morphological, developmental, and life history malformations during endocrine disruption

metamorphosis

paedomorphosis

Page et al., 2007

- Effect of atrazine on growth

- Confirm standrard TH-induction

- Effect of atrazine on metamorphosis

Results Summary

0

10

20

30

40

50

60

70

80

1 2 3

atrazine (ug/L)

pre

-TH

mass (

g)

86

88

90

92

94

96

98

1 2 3

atrazine (ug/L)

post-

TH

len

gth

(m

m S

VL)

0

2

4

6

8

10

12

14

16

1 2 3

atrazine (ug/L)

gil

l le

ng

th (

mm

)

108

110

112

114

116

118

120

122

124

126

128

1 2 3

atrazine (ug/L)

fin

len

gth

(m

m)

pre

-TH

mas

s (g

)

po

st-T

H l

eng

th (

mm

SV

L)

gil

l le

ng

th (

mm

)

fin

len

gth

(m

m)

07

35 0 7

0

35

0 357 7 35

)

)

)

)

40

42

44

46

48

50

52

54

56

58

1 2 3

TH (nM)

pre

-TH

mass (

g)

87

88

89

90

91

92

93

94

95

96

97

1 2 3

TH (nM)

post-

TH

len

gth

(m

m S

VL)

6

7

8

9

10

11

12

13

14

15

1 2 3

TH (nM)

gil

l le

ng

th (

mm

)

100

105

110

115

120

125

130

135

1 2 3

TH (nM)

fin

len

gth

(m

m)

pre

-TH

mas

s (g

)

po

st-T

H l

eng

th (

mm

SV

L)

gil

l le

ng

th (

mm

)

fin

len

gth

(m

m)

0 550

550

0

0 5 50 05

50

ACKNOWLEDGMENTS

Chris Beachy (MSU)Heather Modrow (MSU)Leah Crites (MSU)Charles Crites (MSU)Amanda Lafountain (MSU)Sharon Denks (FBCC)Dwight Blackhawk (FBCC)Erica Goodbear (FBCC)Janel Richter (MSU)Heather Modrow (MSU)Claude Ouedraego (MSU)Karen Pocha-Melby (MSU)

- Accelerated growth at intermediate atrazine dosage; effect is corroborated in our lab in other experiments

- Axolotls undergo metamorphosis after TH-induction

- Failed to find any effect of atrazine on metamorphosis

Summation