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SETAC 2012

Dietary selenomethionine exposure alters aerobic metabolism and methionine catabolism in adult zebrafish. Jith K. Thomas* , Steve Wiseman, John P. Giesy and David M. Janz *Toxicology Graduate Program, University of Saskatchewan, Saskatoon, SK, Canada. SETAC 2012. Introduction.

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SETAC 2012

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  1. Dietary selenomethionine exposure alters aerobic metabolism and methionine catabolism in adult zebrafish Jith K. Thomas*, Steve Wiseman, John P. Giesy and David M. Janz *Toxicology Graduate Program, University of Saskatchewan, Saskatoon, SK, Canada SETAC 2012

  2. Introduction Essential but toxic at elevated concentrations Point Sources - Mining, Coal based power production Non point Sources- Agriculture, Urban runoff Formation of Organoselenium Nickel et al., 2009 Se IV & Se VI Plants & Microbes Direct toxicity? 4 1 2 3 SeMet Se IV- Selenite Se VI - Selenate SeMet - Selenomethionine Modified from USGS

  3. Introduction Question Does chronic dietary SeMet exposure alter repeat swimming performance, metabolic rate and energy metabolism in adult zebrafish?

  4. Experimental Design Adult Zebrafish Control 3 μg Se/g 10 μg Se/g 30 μg Se/g Nutrafin fish food Nutrafin fish food spiked with Se in the form of L-SeMet Fed 90 days (5% body mass/day) No Swim Swim Repeat Swim • Whole body Se concentration • Bioenergetics (whole body triglycerides and glycogen) • Transcript abundance of energy metabolism enzymes • Whole body lactate • Swimming performance and oxygen consumption • Bioenergetics (whole body triglycerides and glycogen) • Whole body lactate

  5. Results & Discussion ICP-MS Total Se Analysis One way ANOVA followed by Holm-Sidak post hoc test. Data are mean ± S.E.M. * , Significantly different from the control group (p< 0.05).

  6. Results & Discussion Morphometric Analysis Condition factor = [ body mass (g)/ length (mm)³ ] x 100,000 One way ANOVA followed by Holm-Sidak post hoc test. Data are mean ± S.E.M. * , Significantly different from the control group (p< 0.05).

  7. Swim Performance • Used Loligo Systems model mini swim tunnel respirometer • Adopted Critical Swimming Speed (Ucrit) test • Ucrit represented as body length per second (BL/s) Ucrit = Ui + [Uii (Ti/Tii)]

  8. Results & Discussion Swim Performance Ucrit – Critical Swimming Speed BL/s – Body Length per second Two way ANOVA followed by Holm-Sidak post hoc test (Factors: Dietary Se treatment factor and swim challenge factor)

  9. Results & Discussion Oxygen Consumption Repeated Measures ANOVA followed by Holm-Sidak post hoc test

  10. Results & Discussion Cost of Transport 9.8 μg/g Repeated Measures ANOVA followed by Holm-Sidak post hoc test

  11. Results & Discussion Metabolic Capacities SMR –Standard Metabolic Rate AMR – Active Metabolic Rate F-AS – Factorial Aerobic Scope One way ANOVA followed by Holm-Sidak post hoc test

  12. Results & Discussion Whole Body Triglycerides Two way ANOVA followed by Holm-Sidak post hoc test (Factors: Dietary Se treatment factor and swim status factor)

  13. Results & Discussion Transcript Abundance of HOAD and MAT 1A in Liver HOAD – β-hydroxyacyl coenzyme A dehydrogenase MAT 1A – Methionine adenosyltransferase 1 alpha One way ANOVA followed by Holm-Sidak post hoc test.

  14. Results & Discussion Whole Body Glycogen Two way ANOVA followed by Holm-Sidak post hoc test (Factors: Dietary Se treatment factor and swim status factor)

  15. Results & Discussion Whole Body Lactate Two way ANOVA followed by Holm-Sidak post hoc test (Factors: Dietary Se treatment factor and swim status factor)

  16. Results & Discussion • Reduced Swimming Performance (Ucrit) • Impaired aerobic metabolism • Greater Triglycerides Accumulation • Down-regulation of HOAD and MAT 1A transcript abundance • Impaired aerobic metabolism Dietary SeMet • Impaired Methionine Catabolism • Down-regulation of MAT 1A transcript abundance

  17. Conclusions • Environmentally relevant dietary SeMet exposure can reduce swimming performance and alter aerobic metabolism in fish and such effects could impact fitness survivability of wild fish inhabiting in selenium contaminated aquatic ecosystems • SeMet-induced down-regulation of HOAD and MAT 1A transcript abundance could be related to greater accumulation of triglycerides • Greater condition factor of fish fed greater concentrations of SeMet suggesting that condition factor is not a good determinant of assessing overall fish health after dietary SeMet exposure

  18. Acknowledgements Committee MembersDr B. Blakley Dr S. Niyogi Dr P. Krone Dr M. Pietrock Dr M. Drew Project Related Help J. Hammel B. Sarauer

  19. THANK YOU

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