I am running a longevity assay with eat-2 and N2 worms. I am raising my worms at 20C in solid media with OP50. I do not have problems with N2 worms, they grow, get old and die normally.
But eat-2 worms grow normally the first 10 days, then a proportion of them (let say 40% of worms) start to look sick. They have a lower density, the intestine looks simpler, they have less spontaneous movements, they shrink.
And finally they die two o three days after. I check the worms every day for vulva prolapse or internal hatching and I censored those animals. But I do not have an explanation for this big proportion of premature dead animals.
Does anyone experience with this mutants ? Is this common? How do you deal with that? Is it possible to avoid this phenomena?
Thanks in advance.
I haven’t run into this specifically, but I have run into weirdness with eat-2(ad1116). The strain we got was wt, but after outcrossing was very sick and starved looking. I expected the starved, but not worms this sick. And the strian has since picked up a new modifier. So I think one has to be very careful with eat-2 strains. A colleague told me that the eat-2 aging data are all over the place in the literature (probably for this reason), so make sure to do good controls!
So, you could be getting secondary effects from a modifier mutation. I was astonished by how quickly the cleaned up ad1116 drifted. I plan to check other alleles. Which allele did you use?
Some of the heterogeneity you observe could be due to different rates of aging within a synchronized eat-2 population. I worked with eat-2(ad465), outcrossed from the CGC stock DA465 five times (against N2) and what I saw is that they exhibit dramatic food avoidance behavior BUT this avoidant behavior declines with age (not at the same rate for different animals and different trials). Needless to say, once they stop avoiding the food and start eating, they also start growing!!! So I ended up with chronologically synchronized animals that varied in their body size (length and width) a lot… Their lifespans weren’t the same, either (not surprising). So it seems that eat-2 are food restricted not only because of the reduced rate of pharyngeal pumping, but also because they avoid food altogether. To get rid of that variable, I spread the bacterial lawn all over the plate.
Check out the reference below. Bottom line: chronically malnourished animals exhibit enhanced food leaving and food avoidant behaviors. “The olfactory neuron AWC promotes avoidance of normally palatable food following chronic dietary restriction” by Birgitta Olofsson J Exp Biol. 2014 May 15; 217(10): 1790–1798.