heSi141 [hlh-8(short)::FLAG::CRE::tbb-2 + unc-119(+)] X. Strain is viable at 15-25 C, but non-tissue specific recombination is observed more frequently in other tissues at higher temperatures (25C). Expression of CRE recombinase in the mesoblast lineage driven by the hlh-8 promoter. Reference: Ruijtenberg S & van den Heuvel S. Cell. 2015 Jul 16;162(2):300-13.

heIs105 [rps-27::loxP::NLS::mCherry::let858 UTR::loxP::NLS::GFP::let-858 UTR + unc-119(+)] IV. heSi141 [hlh-8(short)::FLAG::CRE::tbb-2 + unc-119(+)] X. Maintain at 15-25C. Expression of CRE recombinase in the mesoblast lineage driven by the hlh-8 promoter. heIs105 carries a read-out construct which allows the visualization of the CRE lox mediated recombination in the mesoblast lineage by a switch from red to green. This read-out construct is silenced in the germline. Reference: Ruijtenberg S & van den Heuvel S. Cell. 2015 Jul 16;162(2):300-13.

heSi 143 [rps-27::loxP::mCherry::let-858::fzr-1p::fzr-1::fzr-1 UTR::loxP::GFP::let-858 UTR + unc-119(+)] IV. heSi141 [hlh-8(short)::FLAG::CRE::tbb-2 + unc-119(+)] X. Maintain at 15-25C. Expression of CRE recombinase in the mesoblast lineage driven by the hlh-8 promoter. heSi143 rescues fzr-1(ku298). fzr-1 will be excised upon mesoblast-specific expression of CRE, creating a mesoblast specific mutant of fzr-1. This recombination event can be visualized by a switch from red to green in those cells (the mesoblast) were fzr-1 is lost. Reference: Ruijtenberg S & van den Heuvel S. Cell. 2015 Jul 16;162(2):300-13.

heIs105 [rps-27::loxP::NLS::mCherry::let858 UTR::loxP::NLS::GFP::let-858 UTR + unc-119(+)] IV. heSi164 [rps-27::loxN::NLS::mCherry::let858 UTR::swsn-1p::swsn-1::unc-54 UTR::loxN::NLS::GFP::let-858 UTR + unc-119(+)] V. heSi141 [hlh-8(short)::FLAG::CRE::tbb-2 + unc-119(+)] X. Maintain the line at 15C and shift to 25C for mutant analysis. Expression of CRE recombinase in the mesoblast lineage driven by the hlh-8 promoter. heSi164 carries a swsn-1 rescue construct which ensures rescue of the temperature-sensitive swsn-1(os22) mutation. Upon expression of CRE (in this case in the mesoblast lineage) the swsn-1 gene will be excised, creating a mesoblast specific mutant of swsn-1. This recombination event can be visualized by a switch from red to green in those mesoblast cells in which swsn-1 was lost. The animals are healthy at 15C, but embryonic lethal and larval arrested at 23-25C. swsn-1(os22) causes mild overproliferation in the mesoblast lineage. The swsn-1 rescuing transgene is unable to rescue germline development of swsn-1(os22) mutants. Reference: Ruijtenberg S & van den Heuvel S. Cell. 2015 Jul 16;162(2):300-13.

heSi208 [eft- 3p::LoxP::NLS(egl-13)::tagBFP2::tbb-2 UTR::LoxP::NLS(egl-13)::mCherry::tbb-2 3'UTR] V. heSi141 [hlh-8p::CRE] X. Egg laying defective. LoxN sites in the endogenous swsn-4 locus facilitate inducible knockout of swsn-4. he268 he272 homozygotes are Egl since they cannot form a functioning vulva due to swsn-4 inactivated in the mesoderm lineage by hlh-8p::CRE expression. Reference: van der Vaart A, et al. Sci Adv 2020 May 20;6(21):eaay3823. PMID: 32494730

heSi208 [eft- 3p::LoxP::NLS(egl-13)::tagBFP2::tbb-2 UTR::LoxP::NLS(egl-13)::mCherry::tbb-2 3'UTR] V. heSi141 [hlh-8p::CRE] X. he273 he287 homozygotes are Egl since they cannot form a functioning vulva due to swsn-8 inactivated in the mesoderm lineage by hlh-8p::CRE expression. LoxN sites in the endogenous swsn-8 locus facilitate inducible knockout of swsn-8. Reference: van der Vaart A, et al. Sci Adv 2020 May 20;6(21):eaay3823. PMID: 32494730