Troubling News… …in Genetics?

1. Troubling News… …in Genetics?

2. Pheromones ...Small volatile chemical signals, • function in communication between animals, • act much like hormones in influencing physiology and development.

3. General Odor Reception

4. Pheromone Reception VNO surgical removal removes pheromone response.

5. The Question(s)? Can we genetically dissect behavioral responses? Can we identify a “genetic circuit” that affects behavior in mammals? etc.?

6. map & clone Physiology, biochemistry, more genetics, etc. Need mutant mice lacking pheromone response(s). Forward Genetics Function Phenotype Sequence Complex biological phenomenon, such as behavior, often lack clear, heritable phenotypes.

7. Sequence Gene Disruption Phenotype Homologous Recombination - or other - DNA Genetics Biochemistry Physiology Function Classical Genetics: Phenotype Sequence Reverse Genetics Function

8. foreign DNA Before Regions of Homology Homologous Recombination • the replacement of a gene with an exogenous gene through equal crossing over, After

9. The Question(s)? Can we genetically dissect behavioral responses? Yes

10. Can we genetically dissect behavioral responses? • One region of mouse chromosome 6 has a cluster of 23 Vr1, • 16 functional genes, • 7 pseudogenes, • No other genes in the region, • removing this part of the chromosome should only affect V1r associated biology. V1r Gene Family Tree

11. tail

12. Behavior Analysis What’s different about the KO mice? Experiments derived from VNO surgery results. similar results

13. The Question? Can we identify a “genetic circuit” that affects behavior in mammals?

14. Trpc2 Knock Out Science 22, February 2002 Vol. 295. no. 5559, pp. 1493 - 1500

15. Recombinant Miceinserting the vector(s) via Homologous Recombination • DNA is introduced into embryonic stem (ES) cells via electroporation, • electrical shock makes membrane leaky, • ES cells that have undergone homologous recombination are identified by a selectable marker(s), • and injected into a 4 day old mouse embryo (blastocyst). Electroporation

16. Embryonic Stem Cells - harvested from the inner cell mass of mouse blastocysts, - grown in culture and retain their full potential to produce all the cells of the mature animal, including its gametes.

17. Pseudopregnant Females Vasectomized Males • female mice can be tricked into thinking they are pregnant, • a mouse in estrus is mated with a vasectomized male inducing pseudopregnancy, • if eggs (transformed blastocysts) are implanted, female will become truly pregnant and will give birth to live transgenic offspring.

18. Vasectomizing

19. Successfully transformed ES cells are injected into blastocysts

20. Implantation of Blastocysts • The blastocysts are left to rest for a couple of hours after cell implantation, • Expanded blastocysts are transferred to the uterine horn of a 2.5 dpc pseudopregnant female, • Viable pups are born.

21. Implanting blastocysts

22. Implanting Blastocysts (cont.)

24. Littermates Black mouse - no apparent ES cell contribution, Chimeric founder - strong ES cell contribution, Chimeric founder - weaker ES cell Contribution.

25. Chimeric mouse Black/White Chimeric Example Cross and look for offspring with germ-line transfection.

26. Trpc2 Knock Out Confirmation Southern Western Science 22, February 2002 Vol. 295. no. 5559, pp. 1493 - 1500

27. in situ Hybridization Science 22, February 2002 Vol. 295. no. 5559, pp. 1493 - 1500

28. Heterozygous females are +/- like Mutants…

30. Female Intruder Male Intruder Heterozygous Female Homozygous Female

31. Ultrasonic Sound

32. What do You Think? Can we genetically dissect behavioral responses? Can we identify a “genetic circuit” that affects behavior in mammals? Questions?