Hello Everyone!
Please I am interested to know what happened to the L1 stage after very long time of starvation, do they die, enter dauer larva stage or ?
Thanks
if you have a read through Patrick’s chapter in WormBook http://wormbook.org/chapters/www_dauer/dauer.html
you can see, that one of the environmental influences for dauer formation is food supply, so i guess they could go into dauer.
M
[EDIT: what is was writing was shown wrong later in the thread,]
I have two strains that arrest, and then eventually die. I don’t know if this is typical or not.
-j
L1 don’t go into dauer. Dauer is an alternative 3rd larval stage, not a state that is accessible for a starved L1. Eventually, starved L1 will die, but they can live for quite a while before that happens.
But there is a publication that starved L1 can go into predauer (L2d) to dauer if starvation persist and upon favorable condition enters L3 stage instead of L4 as observed in dauer larvae. It’s really confusing.
Thanks
Can you give us that reference? That would be helpful to discuss it specifically. In my experience starved L1s arrest and then die if food is withheld for too long (as Dana was describing). See Baugh and Sternberg, 2006 for the survival rate of different mutants after 21 days of starvation (Fig. 1C).
If there is no food at hatching, worms go into L1 arrest and after about 2 weeks they die (they do NOT go into L2d) or if they find food they proceed to L2. if there is food initially and they pass L1 arrest stage (right after hatching) but then encounter crowding, high temperature, low food they go into L1/L2d molt instead of L1/L2 molt and proceed into dauer. You can see a graphic presentation in wormatlas introfig6 (http://www.wormatlas.org/hermaphrodite/introduction/Introframeset.html)
I think you could tell it easily whether your starved L1 arrest worms enter dauer by SDS- resistant assay.
this topic has been sleeping peacefully for a long time now, but as I am interested in what happens to L1 worms in bacteria-free conditions as I’m working with them at the moment, I read through the mails on this topic.
Anasha said that there was a publication stating that L1 pass through L2d under conditions of starvation rather than arresting and then a few weeks later dying.
Sure enough I found a plos essay paper stating this was the case. Or was this a typo?
At the moment, it seems the weight of opinion is that starved L1s DO NOT enter L2d (taken from comments in this forum) and accepted wisdom…
…and (at least?) one paper;
http://www.plosbiology.org/article/info:doi/10.1371/journal.pbio.1001050
(figure 1)
that states it does. I guess that by the ned of next week I’ll know the truth…or…
Steve
@steveh
If the worms hatch in the absence of food, they arrest in L1 diapause. None of the normally scheduled cell divisions will happen and the worms waits for better times to come around. They are different from dauer in that they are not resistant to SDS (among other things) and they will run out of resources and die after a few weeks (see the article by Baugh and Sternberg I quoted earlier in this thread).
If they hatch and initially have food (and thus pass the L1 diapause checkpoint) and subsequently run out of food, they will commit to going into dauer. The first step along the way to being a dauer is to be an L2d, which is indeed triggered by all the things mentioned in Fig 1 of your PloS paper. This is, however, different from L1 diapause.
Animals that initially arrest in L1 and are subsequently re-fed will develop normally through L2 and L3, not L2d and dauer.
Hope this helps.
Toby
Toby,
thanks for you reply.
I think the key point you make which is a little fuzzy in some of the discussions and in some papers including the plos paper, is the distinction between L1 worms that never see food and arrest in L1 diapause and those L1 worms that run out of food and enter the dauer pathway via the L2d stage.
Steve
Hello,
I am treating my worms with low dose of Paraquat.
They grow normally till L2 stages, and then majority goes into L3 -L4 stages and the others arrest, which seems like Dauer from their appearance.
So is it possible for the mutant worms to go into Dauer post L2 Stage? Or is it just another phenotype of the worm I am observing but not the actual Dauer?
Thanks.
Hello Sanjib,
it would be useful if you could describe in a little more details what you are observing.
For example, you say that the worms grow normally until ‘L2 stages’…
Do you mean until they begin the L2 stage?
You say the majority progress on to later stages but that ‘others arrest’…
Are the arrested worms found on the same plate as the normally developing worms and if so how many as a percentage?
You mention ‘mutant worms’…
What kind of mutant worms are these (genotype), are they temperature sensitive etc?
The dauer phenotype is the dauer phenotype, that is, if your worms look like dauers then they probably are!
Give us a little bit more to go on and perhaps we can help…
Steve
I would also like to mention that worms do transition from L2 to dauer. Dauer is an alternative L3, so it’s expected that you’ll go from L2 (actually L2d) into dauer. The decision is made in the L1, but the dauer comes after L2.
The other Steve
Hello,
Thanks, both the Steves for replying. I lost my old password, so replying with a different account.
But anyway to answer the First Steve´s queries -
Yes, from the eggs till L2 my mutant worms grow normally, then after, some goes into L3-L4 and on and the other stays as dauer.
Yes they are on the same plate, like 20% is dauer and remaining 80% is L4 and young adult (after 96hours).
My mutant is not temparature sensitive. and my plates are not starved. As I put 10 eggs per plate which has low dose of paraquat.
Thanks,
Sanjib
Sanjib,
OK.
But there are still several reasons why you could observe such a phenotype in a proportion of your mutant worm population.
Without knowing the identity of the mutant and/or whether it has been outcrossed (if it’s a new mutant) to remove the possible confounding effects of other mutations, narrowing down the reason is made more difficult.
For instance, if the mutant has to remain anonymous, can we assume that your mutant is well established (homozygous), outcrossed and involves a gene that one would not automatically associate with moderately penetrant a daf-c phenotype?
Steve