1. Heat-Stress Resistance & Aging
By: Scott Scholz
Phillips Lab ’09
Mentor: Rose Reynolds

2. Aging:
The gradual changes in the structure and function of humans and animals that occur with the passage of time, that do not result from disease or other gross accidents, and that eventually lead to the increased probability of death as the person or animal grows older.

3. Aging
Vs.
70 year old men

4. What Determines the Differences Between Individuals?
Are there genetic differences in humans that cause us to age at different rates?
Model: Caenorhabditis remanei
In chemosensory genes C. remanei has been found to have 200x the genetic diversity of C. elegans.
People appear to age at different rates…
So we want to know if there are genetic differences that contribute to these differences. Since humans are very difficult to study we turn to the free-living nematode, Caenorhabditis remanei. C. remanei is an ideal organism for our purposes because it shares many useful features with the established model, C. elegans such as a short generation time and large number of offspring. Remanei however, have significantly more genetic diversity than elegans which is very important for us since we are interested in natural variation in aging.
Jovelin (2008)

5. Variation of Lifespan in C. Remanei
Research on natural variation in Lifespan has been going for some time in the phillips lab. Here is a graph of lifespan of several strains of C. remanei already examined by my lab
Fraction survival is on the Y axis. 1 is where all of the worms are surviving. The X axis is age of the worms in days.
So we see that there appears to be some variation in lifespan between strains. Huge research efforts have revealed many players in the molecular signaling pathway that effects lifespan called the insulin-like signalling pathway.
Reynolds (Unpublished)

6. Insulin-like Signaling Pathway
This is a diagram of the insulin-like signaling pathway. This diagram is pretty full so I’d like to just draw your attention to some specific proteins.
When genes coding for DAF-2 of AGE-1 get a null mutation they no longer signal down the pathway for Daf-16 to become phosphorylated. Daf-16 can then enter the nucleus and upregulate transcription of genes contributing to longevity and stress resistance.
Stress resistance and Lifespan are genetically correlated!
Cohen & Dillin 2008

7. Heat-Stress Resistance
Heat-stress resistance can be very important for a soil-dwelling worm.
Much more time efficient way of testing lifespan.
Find other players in regulation of lifespan and stress-response.
Pt 1- self
Pt 2- since heat-stress resistance has been shown to be so highly correlated to lifespan, heat-stress resistance might be able to be used in place of a lifespan assay instead of waiting 25+ days for all of the worms to die
Pt 3- Look at regions of the genome that affect only lifespan or heat-stress resistance to gain a better understanding of how Daf-16 transcriptionally regulates and what genes coding for proteins in this pathway are causing differences between individuals?

8. My Goals Develop an assay to test heat-stress resistance.
Assay several natural C. remanei isolates for variation in heat-stress resistance. 8

9. Develop Heat-Stress Assay
Use the representative C. remanei line PX323 to find the LD50 of heat.
Many challenges in treating worms with an even “dose” of heat.
Heat uniformity over area
Heat stability over time
Even heating to target temp
Heat-stress resistance can be very important for a soil dwelling worm
Add kill curve to explain LD50
Add picture of methods (inc) to explain on… (gels)
Make a list of what I tried for methods. & how long it took!
Which led me to find

10. Approach 31 Alive / 60 Total = 0.52 Survival. 52% Survived 16 hrs
Pick L4 Females
24+ hrs
Virgin Adult Females

11. Test Heat-Stress Resistance
Find LD50 temperature (over 16hrs)
Graph a composite of different methods

12. Future
Test several natural C. remanei isolates for variation in heat-stress resistance.
Use known markers to identify regions across the genome that affect heat-stress resistance, lifespan or both!
Compare male vs. female heat-stress resistance and the significance of C. remanei being dioecious.
Reproduction?
Test to see if lifespan is correlated with heat-stress resistance

13. Thanks! Rose Reynolds The UO SPUR program Peter O’Day & Chelsie Fish
The Entire Phillips Lab