1. 2012 LIFE Scholars Presentation
Sada Egenriether

2. Background Lab Focus Aging Biomarkers of Aging
Circadian Biology
Biomarkers of Aging
Dampened circadian oscillation
Decline in climbing ability
Decline in smelling ability: potential biomarker of brain function decline?
Tonoki and Davis, 2011

3. Pilot Experiment Rejected! Purpose 1
Examine changes in the sense of smell in aging flies
Rejected!
Hypothesis 1
Older flies will require more time to find food due to decreased olfactory (smelling) function
Procedure
To test, flies were placed in petri dish “arena” with access to a food trap
Food Trap

4. Procedure 1. Rearing flies 2. Starvation 3. Transfer 4. Observation
Flies were grown at specific time intervals to ensure groups reached ages 35d and 5d simultaneously.
2. Starvation
Once flies reached target age, all were starved for 14h, the optimum starvation period for a one-day experiment
3. Transfer
Starved flies were immobilized by briefly cooling and were loaded into trap arenas
4. Observation
The number of trapped flies in each arena was recorded at half hour intervals for the first 2h, then again at 4h, 10h, and 24h
Starve
Transfer
Observe

5. Results
As in pilot experiment, old flies located food more quickly than young flies

6. Possible Explanation
Older flies have smaller fat reserves to draw on, which reduces the length of time they can go without food before they initiate food search behavior.
To Test:
Groups of old and young flies were loaded into agar (starvation) vials
Number alive and dead in each vial were recorded every 12h

7. Starvation Results
Results of starvation experiment agree with trap results.
Young flies survived starvation significantly longer than old flies.

8. Experiment 2 Starve 14h Transfer Observe Starve 25h
Purpose
Compare the time required to locate food in young flies subjected to increased starvation duration
Hypothesis
Young flies starved longer will locate food more quickly
Procedure
Food trap procedure repeated, but with only young flies: one group starved 14h and another 25h
Starve 14h
Transfer
Observe
Starve 25h

9. Results
Young flies starved for 25h found food more quickly than young flies starved 14h
(movie here)

10. Results
Young flies starved for 25h found food more quickly than young flies starved 14h
These results suggest that young flies require a much longer starvation duration than old flies before they initiate food search behavior.

11. Possible Explanation
Food search behavior may be related to changes in insulin signaling.
Root et al, 2011
Research in young flies suggested that the insulin receptor in neurons that detect odors is the metabolic sensor that triggers food search behavior

12. Possible Explanation Low Insulin High Insulin InR-DN InR-CA
Receptor cannot signal
InR-CA
Receptor constitutively active
Receptor Inactive
Receptor Active
Food Search Increased
Food Search Decreased
Is a change in insulin signaling responsible for the faster initiation of food search behavior in old flies?

13. Next Experiment
Purpose
Examine food search behavior in flies with genetic mutations associated with insulin signaling
Young flies with InR-DN will find food more quickly than wild-type control, while old flies with InR-CA will take longer than wild-type control
Hypothesis
Procedure
Food trap procedure repeated with young and old flies of both InR-DN and InR-CA phenotypes.

14. No significant difference was observed in the time required to find food between control and InR-DN flies of either age.
CA Old
Food search behavior was delayed in old flies with InR-CA.

15. Genotype
Age
EtOH/RU
Median
Chi Square
p value CA
Old
EtOH 48
43.12
<0.0001 RU 60
Young 84
3.66
0.0555 72 DN
18.62 54
33.52
Survival curves for all but young InR-CA showed significance with Chi Square of median survival.

16. References
Root, C. M. et al. (2011). Presynaptic facilitation by neuropeptide signaling mediates odor-driven food search. Cell, 145(1),
Root, C. M. et al. (2011). Aging impairs intermediate-term behavioral memory by disrupting the dorsal paired medial neuron memory trace. Neuroscience, 109(16),