i’m currently performing life span analyses. one genotype show a strong protruding vulva (pvu) phenotype. do i have to exclude pvu-worms from the life-span analysis, or only worms with a bursted/disrupted vulva?
thanx in advance,
Difficult one. I guess you have to ask whether you think pvu can affect lifespan in any way, e.g. does it result in inappropriate exposure to bacteria of bits that normally aren’t? And then you have to ask if you do exclude the pvu worms, could you be selecting against worms that have the stronger phenotype, and hence affecting your data?
Sorry can’t be of more help,
I have had the same issue when I first started doing life span assays. When I asked around the more experienced “life spanners” they all gave me different answers ;D But the take home message was that you have to be consistent throughout all your life span assays and with all the genotypes/conditions you are using (including life span repeats). The problem is that some genotypes do not have form the puv phenotypes as much as others might do, thus Ben is right, you might be selecting for the “fittest” by excluding the puv. worms.
Also, when performing life span assays, it is best to exclude any conditions that might kill the worm as this will interfere with your results. Here is what I do in my life spans:
*exploded vulva eventually kill the worm so I censor worms with exploded vulva.
*protrusions: I keep on scoring/including them in my life span until:
a: the worm dies (and the puv phenotype is more or less the same), and here I score it dead.
b: the puv phenotype develops to become a bursted/exploded and at that point I censor them.
In other words, I keep the pvu worms up to a stage when I either censor them or score them as dead (provided that the puv phenotype has not gone worst).
Another suggestion is to choose the conditions that reduce the formation of the vulva phenotypes (e.g changing the temperature at which you perform life spans, the use of FudR etc)
That is all that comes to my mind.
All the best with your experiments,
Thank you very much, Ben and Lamia! Your answers helped me lot. Im now scoring like Lamia said. Thanx again. Cheers, oldcoffee.