Hi, I’m having trouble understanding the exact differences between the conditions and pathways involved in arrest and those involved in dauer arrest. Does anyone know if there is a source that can help clarify this? I’ve read the studies involving starvation-induced arrest at L1, and from what I’ve read dauer arrest occures during L2 (predauer) and forms after the L2d molt. So, obviously this starvation-induced L1 arrest can’t lead into dauer arrest if the worms never make it to L2. So does that mean there’s three possible states the worm can be in (reproductive growth in the best conditions; dauer arrest in bad conditions; arrest in the worst conditions)?
Also, is this starvation induced arrest reserved for L1’s or can it occure regardless of the onset of starvation? Since most worms have made a commitment to reproductive growth versus dauer at the L1 molt, does this also apply to arrest?
If anyone can clear some of this up for me I’d be forever greatful. Thanks,
Greg Sliwoski
gsliwoski@mclean.harvard.edu
Hi,
I’m no expert on this, but L1 arrest is distinct from dauer, as you say. As far as I know this type of arrest
happens only to embryos hatched in the absence of food. And it’s rather specific. Therefore, I think you couldn’t call
it an arrest in “worst conditions”. I think it woud be different from an L3 worm that you put on a plate
with no food. Anyway, what happens with L3 or L4 worms that you transfer fr?m food to no food.
Do they arrest? Or do they just became scrawny and necrotic, eating up their own internal resources?
Hello Professor,
I am doing the dauer assay with daf-22. (Small NGM plates, 50ul E. coli, starved for a week)
But I not getting any dauer with this mutant.
Is it normal? Or I should get atleast a very low percentage of dauers with it.
P.S. With wild type, I get a high number of dauers…
Thanks.
Hi,
I’m not a professor, but perhaps you should read the original Golden & Riddle paper?
http://link.springer.com/article/10.1007%2FBF00332953?LI=true
Regards
Steve
Seems like daf-22 is dauer defective, not dauer constitutive. So it seems like your assay is working fine. Sometimes it works even better at 25°C.
In fact, the daf-22 mutant was isolated based on its inability to form dauers, so this is normal.
As for the original question, I have mostly worked with dauer larvae and not other kinds of arrest. They do need some food to make it to the dauer stage, which makes it distinct from L1 arrest. There’s also the adult reproductive diapause, a very interesting discovery.
I’m not sure what happens when you outright starve an L2-L4. My guess is similar to Dr. Burglin’s that the worms will become scrawny and necrotic or arrest somehow. Perhaps you could test this!
Hello Dr. Steve,
I cant get access the original Golden & Riddle paper…
Can you please send me sanjibcsu@gmail.com
Thanks a lot to everyone.
Hi,
as the article is subject to copyright, sending you a copy would not be construed as ‘fair use’ by the copyright holder or probably by my uni!
HOWEVER, if you’re a student at (I’m guessing from the email) Colorado State then I would expect that you should be able to get direct access to this article via your faculty library or indirectly via interlibrary loan.
That said, I wonder why/how you started a project and experimental work using the daf-22 mutant without having read the original paper describing its isolation and its identification as Daf-d??
I think you should also read through this chapter of the worm book to get a clearer picture of what dauer is…
http://www.wormbook.org/chapters/www_dauer/dauer.html
Regards
Steve