This document analyzes the effects of the pesticide fipronil on notochord development in zebrafish, highlighting its role as a neurotoxin that damages the notochord. The study concludes that higher concentrations of fipronil lead to greater damage and necrosis, with behavioral responses indicating neurodegeneration. Future research is suggested to include antibody staining to further investigate the notochord's condition.

1. The Effects of fipronil on notochord development in Zebrafish Joshua Mendoza-Elias Biology 205L Experiments in Developmental Biology Fall 2006

2. Backgr ound on Fipronil Pesticide Blocks GABA receptors Teratogen Found to cause notochord damage in zebrafish --> Chordates GABA R active at 30 hours AEL Stehr et al. 2006

3. Background- Accordian Phenotype

4. Question : (i.) Early on, will exposure to Fipronil cause neurodegeneration in notochord? (ii.) Will the damage be necrotic tissue? (iii.) Will their be damage elsewhere? (i.) Fipronil damages notochord (ii.) Damage will result in necrotic tissue Hypothesis:

5. Materials & Methods Control (0.1% acetone) 0.7  M Fipronil (0.1% acetone) 1.1  M Fipronil (0.1% acetone) 2.3  M Fipronil (0.1% acetone) Notochord Morphology Acridine Orange Staining Behavioral Response

6. Results-Behavioral Response 36 hrs - Control

7. 36 hrs - 0.7  M

8. 36 hrs - 1.1  M

9. 36 hrs - 2.3  M

10. Results-Behavioral Response 48 hrs - Control

11. 48 hrs - 0.7  M

12. 48 hrs - 1.1  M

13. 48 hrs - 2.3  M

14. Results-Notochord Morphology Control: 36 hrs, 48 hrs

15. 36 hrs, 48 hrs - 0.7  M

16. 36 hrs, 48 hrs - 1.1  M

17. 36 hrs, 48 hrs – 2.3  M

18. Results 39 Total moderate: Total severe: 15 Total WT: 7 Total moderate: Total severe: Total WT: 36 hrs 48 hrs 23 31 10 24.59% 69.93% 11.47% 35.93% 48.43% 15.62%

19. Results-Acridine Orange Staining

20. Discussion Notochord damage first occurs anteriorly Higher concentration = more damage Higher concentration = damage sooner  Exposure time = more damage

21. Future Directions Anti-body staining Examine upper notochord Circulation

22. References: [1] Stehr. C., Linbo, L.L., Incardona, J. P, Scholz, N. L. 2006. The developmental neurotoxicity of fipronil: notochord degeneration and locomotor defects in zebrafish embryos and larvae. Toxicological Sciences . 2006 92 ( 1): 270 -278. [2] Incardona, J., Stehr, C., Linbo, T., Scholz, N. Fipronil causes locomotor defects in developing zebrafish. 2006. Marine Environmental Research. 2006. 62 : S74 -S75. [3] Cole, Loretta M., Russel A. Nicholson, and John E. Casida. 1993. Action of phenylpyrazole insecticides at the GABA-gated chloride channel. Pest. Biochemical Physiology . 46 : 47-54. [4] Hamon, Nicholas, Richard Shaw, and Henry Yang. 1996. Worldwide development of fipronil insecticide. Proc.-Beltwide Cotton Conference. 2 : 759-765. [5] Colliot, F., K.A. Kukowskim P.W. Hawkins, and D.A. Robers. 1992. Fipronil: a new soil and foliar broad spectrum insecticide. Brighton Crop Proteonomics. Conf.-Pests Dis. 1 :29-34.

23. Acknowledgements Dr. B Dr. P Nicole Roy Wendy Beane Monica Zhang