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Pam Clarkson

Effects of atrazine on thyroid hormone induction of metamorphosis in the axolotl ( Ambystoma mexicanum ). Pam Clarkson. ENDOCRINE DISRUPTION. ATRAZINE. -- Post application (Spring) runoff can be > 20 ppb

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Pam Clarkson

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  1. Effects of atrazine on thyroid hormone induction of metamorphosis in the axolotl (Ambystoma mexicanum) Pam Clarkson

  2. ENDOCRINE DISRUPTION ATRAZINE -- 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 Males exposed to 0.1 ppb have lowered testosterone, elevated estrogen, and intersex gonads Xenopus laevis Hayes et al, 2002, PNAS

  3. 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

  4. Big Picture To begin characterization of gene expression during salamander metamorphosis Hypothesis: no variation in gene expression during metamorphosis For comparison to endocrine disrupted metamorphosis To correlate patterns of gene expression with morphological, developmental, and life history malformations during endocrine disruption To identify loci that will be useful in field diagnostics of normal and endocrine disrupted metamorphosis

  5. paedomorphosis metamorphosis

  6. Page et al., 2007

  7. Results Summary - Effect of atrazine on growth - Confirm standrard TH-induction - Effect of atrazine on metamorphosis

  8. pre-TH mass (g) post-TH length (mm SVL) 7 7 0 ) 35 0 ) 35 gill length (mm) fin length (mm) 0 7 35 0 7 35 ) )

  9. pre-TH mass (g) post-TH length (mm SVL) 0 5 5 50 0 50 gill length (mm) fin length (mm) 5 0 5 50 0 50

  10. 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)

  11. Summation • - 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

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