1. Development of DA and 5HT neurons involved in reward- associated behavior in zebrafish Su Guo, Ph.D. University of california, San Francisco

2. 3-day old zebrafish labeled with anti-TH and 5HT antibodies Basal forebrain DA and 5HT neurons

3. Questions Do zebrafish have reward-associated behavior? –Experience-dependent morphine preference Do the basal forebrain DA/5HT neurons play a role in this behavior? –The too few mutant How is the development of basal forebrain DA/5HT neurons regulated? –The foggy mutant

4. Zebrafish: a vertebrate genetic model organism Small-size High fecundity Easy to maintain In large numbers Rapid development Optically transparent In vivo tracing of biological processes

5. What is reward-associated behavior? A prior exposure to a substance elicits a preference behavior for the substance: –Spend more time in the substance-paired side (CPP) –Self-administer the substance

6. Studying reward-associated behavior in larval zebrafish Larval zebrafish are amenable to genetic analysis and the study of cellular mechanisms Larval zebrafish are free-living (food hunting, escaping) The nervous system of larval zebrafish is more plastic than adult zebrafish.

7. Choice chamber drugwater draining Pre-expose larval Zebrafish to the drug Test their preference for the drug in the choice chamber

8. Larval zebrafish show experience- dependent preference for morphine

9. Morphine preference is dependent on opioid receptors

10. The too few mutant

11. The basal forebrain DA/5HT neurons are required for morphine preference behavior

12. Functional analogy of zf basal FB to mammalian MB DA neurons Mammals: adapted from Kandel’s Principles of Neural Science Zebrafish: adapted from Rink and Wullimann, 2002 tfu

13. How is the development of basal FB DA and 5HT neurons regulated? Will the mechanisms be homologous to mammalian FB or MB neurons? What are the genes and pathways involved in the development of these neurons?

14. Mutagenesis screen

15. Mutations affecting the development of basal FB DA/5HT neurons too few motionless twin-of-motionless foggy

16. The foggy mutant WTfoggy

17. foggy encodes a regulator of transcription elongation

18. The importance of regulating transcription elongation during development promoter Transcription initiation Transcription elongation

19. foggy expression

20. The foggy mutation selectively disrupts its repressor activity Repressor Activator

21. Question What genes are de-repressed that leads to defects in DA/5HT neuron development? –Micro-array study How is foggy’s repressor activity regulated during development? –Focus on the function of the C-terminal domain, where the foggy mutation resides.

22. Summary Zebrafish is an attractive genetic model organism to study: – the development of specific neuronal types. –The developmental alteration that leads to abnormal reward-associated behavior.

23. Acknowledgements Sandrine Bretaud Brent Lockwood Reward-associated behavior in larval zebrafish Foggy regulation Jae-yeon Jeong Foggy downstream tergets Keerthi Krishnan Arnon Rosenthal (Rinat Neuroscience) Mark Fishman (Novartis) Wolfgang Driever (University of Freiburg)