eat-2 drift

Inspired by another thread… (Edit, linky: http://forums.wormbase.org/index.php?topic=2555.0)

So we got eat-2(ad116) from a colleague to use as a valuable dietary restriction (DR) tool. I was surprised to find the animals looking wt. Upon outcrossing they were much more starved looking, and many animals arrested. I plan on cleaning ad1116 up further and trying some other eat-2 alleles. But a colleague at the meeting told me that eat-2 data with regard to aging are all over the place. I can imagine a lot of people simply using feeding RNAi, which present its own problems with a worm that eats poorly. But I can also imagine baselines varying enormously.

Will other people share their experiences with eat-2? Which alleles, where did you get them, did you outcross them? I was really stuck by how strong this phenomenon was, and how quickly our cleaned up eat-2 drifted again (yes, I am sure we got rid of the original modifier(s)).

Seems like an important question. And for that matter, have there been eat-2 suppressor screens?

Note: ad1116 is a splice acceptor mutation at the beginning of exon 4 (of 6), so is probably a strong loss. But the suppressors are clearly not intragenic, so I’m not sure this would matter. Maybe a weaker allele would be more reliable and still give a strong DR longevity phenotype?

I’ve never even touched an eat mutant, so I have no personal practical experience.

Still, I wonder: it’s known that you can suppress the worst effects of some eat mutants by replacing OP50 with an easier-to-eat strain of E. coli, so it’s reasonable to suppose some eat mutants would be sensitive to subtler contamination or alteration of their food supply. Maybe some of the variation you’re seeing for eat-2 mutants between strains and over time has nothing to do with the worms directly but reflects contamination of or even changes to the OP50?

Indeed Dave, the eat-2 data is all over the place despite most people using the universal-ish ad1116 allele. Yep, food quality does make a big difference as we’ve done some experiments using OP50 from some of our neighbouring labs and got variable lifespans.

I have seen drift of this allele once, rescuing back to wt as you have described. I didn’t think much of it and tossed it out. I’ve never seen this with ad1113 though.

We got our eat mutants many years ago from the CGC. We have outcrossed them at least 3-5x each originally. Not sure if anyone has done an eat-2 suppressor screen, but my best guess as to who would’ve tried is Leon Avery.

Edit: Also, with respect to doing the screen, eat-2 worms are pretty sick and unhappy. I imagine doing a suppressor screen of the lifespan phenotype of eat-2 would actually be hard, because you’d probably just get things that shorten lifespan because of making them sicker, rather than actually interfering with DR signalling.

Thanks for the comments!

  1. This is almost certainly OP50 we are working with, and we have done the outcross multiple times.

  2. Snug’s comments are supported by these comments in the other thread:
    http://forums.wormbase.org/index.php?topic=2555.msg6485#msg6485
    The description matches my observations quite well.

  3. For suppressor screen I was thinking the starved/sickly phenotype, not aging! The former would practically be a selection.