a lifespan question in a new published paper

I am reading a new published paper “An age-dependent reversal in the protective capacities of JNK signaling shortens Caenorhabditis elegans lifespan”. And I got couple of questions…

Basically they examined the effects of vhp-1 knock-down on lifespan. What they performed was rearing worms on dead food bacteria to observe the lifespan. Since I donot work on lifeapan stuff, I have no idea why they let the worms eating daed food bacteria instead of normal food.
FYI: They did try to compare different food effect on lifeapan.

Any comments are welcome. If you are also reading the paper, I will be very happy to discuss with you. Thank you in advance.

Emily

Have a look at this previous thread, and the Kenyon paper cited there.

Previous research have shown that live bacteria do have some negative effect on the lifespan of worms. More likely, it involves the bacterial secretions and metabolites. So a number of lifespan studies try to see if the effect of the chemical is direct on the worms themselves, or if it is affecting the bacteria and as a consequence extending the lifespan. Hope this helps. Good luck!

Thanks a lot for all your answers. I really learned from it.