ltIs37 [pie-1p::mCherry::his-58 + unc-119(+)] IV. meIs1 [pie-1p::GFP::lacI]. Made by crossing AV221 with OD56. Reference: Yuen KW, et al. Curr Biol. 2011 Nov 8;21(21):1800-7.

meIs1 [pie-1p::GFP::lacI + unc-119(+)]. meIs4 [lac-O + rol-6(su1006) + lacO] IV. Pick Rol worms to maintain. This strain throws both Rol and non-Rol worms, seemingly due to random silencing of rol-6(su1006) in the lacO array, meIs4. The strain expresses GFP::LacI in the gonad and embryos that is observed as foci (of lacO target) and nuclear haze. The expression level of GFP::LacI occasionally becomes low possibly due to random silencing of meIs1. If this happens, heat shock the strain at 25°C for 3 days, and pick a clone that exhibits bright GFP signals. Even at the highest expression level, GFP signal is too weak to detect with a fluorescent dissection microscope, and it is necessary to use a regular compound fluorescent microscope with an oil immersion 60X or 100X objective. The NA of the objective should be higher than 1.4. Reference: Bilgir C, et al. G3 (Bethesda). 2013 Mar 11. pii: g3.112.005165v1.