1. C. elegans Behavior

2. Background Information

3. Anatomy of the Worm XX

4. Most worms are which sex?

5. If hermaphrodites are XX, and males are XO, which process must happen to result in a male worm?
Nondisjunction

6. Male Worms Only occur in 0.1-0.2% of “normal” stocks
Although there are ways to breed more males
Through mating or him mutations

7. Worm Lifecycle
C. elegans’ entire life cycle, from egg to adult, occurs in 3.5 days
Wild-type worms live anywhere from days
Lifespan is affected by strain, temperature (best at 20 deg C), food intake, etc.

8. Dauer Formation
Harsh environments trigger L1s to arrest development as dauer larvae
Triggered by little food and overcrowded conditions
Dauer recovery (exit from dauer stage) is also dependent upon low population density.

9. C. elegans as Model Organisms
Entire genome sequenced (1998)
Every cell lineage is known
959 cells in hermaphrodites, 1031 in males
Small, quick lifespans, easy to breed
Transparent bodies

11. Fun Fact! 

12. Your experiment

13. What is the daf-18 gene? What are we looking for?

14. Day 1: Subculture

15. Tips
Make sure you wait for the pellet and GET PLENTY OF WORMS ON THE PLATE
Check under a microscope to make sure
Label well: Don’t mix up your strains 

16. Day 2: Chemotaxis Experiment

17. Tips Kimwipe up all M9 buffer!!!
Counting: Use a compound light microscope

18. Calculate Chemotaxis Index

19. What are you expecting?