counter-selection strategies

Model Organism: Worms Methods & Reagents
1

I’m trying to generate a list of counter-selection strategies that are either known to work in the worm or should/could work.
So far, I’ve got -

wt ben-1 expressed in ben-1 strain with benomyl selection
wt avr-15 expressed in avr-14/avr-15 strains with ivermectin selection
wt unc-29 in unc-29 strain with levamisole selection

Any others…?

2

heat-shock inducible peel-1?

3

I haven’t seen it done (I haven’t looked very hard), but you could possibly develop a system using ceh-28::dat-1 and 6-hydroxydopamine.

4

I don’t know if anyone has tried it, but before the peel-1 and the ivermectin approaches came out I was considering trying ura3 or hprt counterselection. Looks like both are reported to work in both budding yeast and mammalian cells. I never actually tried either, though.

5

Could you use a temperature sensitive strain? For example, lin-15 expression in a lin-15(n765) background. At 25°C only lin-15+ worms will grow.

6

dweinkove,

Unless you’ve got a good dominant-negative transgene in mind, that’s selection instead of counter-selection.

(also, lin-15(n765) will grow at 25C, albeit more slowly than the wild type and Muv)

7

Good idea but not sure if that actually does enough ‘damage’ to differentiate them. How about a transgene that confers a dominant
locomotory defect? For example, glr-1::GLR-1(A/T) as described in Zheng et al (1999), increases reversing making worms relatively
‘immobile’. One could then select as for unc-119 via ‘reverse chunking’. Maybe even rol-6 would work.

8

you might want to read through this review if you haven’t already…not ‘directly’ relevant (but that’s me I’m afraid) but very informative. Who knows, perhaps it sparks a few ideas.

http://iai.asm.org/content/66/9/4011

Steve