To generate primary transgenic animals, we used (CBAxC57BL/6)F1 zygotes obtained from 3-week-old CBA and C57BL/6 breeders (Stolbovaya breeding station, Russian Federation). The transgene DNA construct was introduced by pronuclear microinjections as described earlier (Zvezdova et al. 2010 (link)). Surviving zygotes were cultivated in M16 medium at 37 °C and 6% CO2 for 24 h and then transplanted into the oviducts of foster mothers at the 2-cell stage as previously described (Silaeva et al. 2018 (link)).
The B6. Cg-Ndor1Tg(UBC-cre/ERT2)1Ejb/1 J, also known as Ubi-Cre, mouse strain was purchased from the Jackson Laboratory (Goodwin et al. 2019 (link)). In this strain, chimeric Cre recombinase is expressed under the control of the UBC promoter. Chimeric Cre recombinase consists of a Cre recombinase domain and a domain representing a mutant form of the estrogen receptor, which lacks the ability to bind natural 17β-estradiol and binds only synthetic tamoxifen. Without tamoxifen, the protein is restricted to the cytoplasm, and only in the presence of tamoxifen translocates to the nucleus and performs recombination. Ubi-Cre mice can be maintained only in hemizygotes.
Animals were kept in the IGB RAN vivarium with artificial lighting (12 h/12 h mode) at a temperature of 21–23 °C and humidity of 38–50%; mice had free access to food and water.
The B6. Cg-Ndor1Tg(UBC-cre/ERT2)1Ejb/1 J, also known as Ubi-Cre, mouse strain was purchased from the Jackson Laboratory (Goodwin et al. 2019 (link)). In this strain, chimeric Cre recombinase is expressed under the control of the UBC promoter. Chimeric Cre recombinase consists of a Cre recombinase domain and a domain representing a mutant form of the estrogen receptor, which lacks the ability to bind natural 17β-estradiol and binds only synthetic tamoxifen. Without tamoxifen, the protein is restricted to the cytoplasm, and only in the presence of tamoxifen translocates to the nucleus and performs recombination. Ubi-Cre mice can be maintained only in hemizygotes.
Animals were kept in the IGB RAN vivarium with artificial lighting (12 h/12 h mode) at a temperature of 21–23 °C and humidity of 38–50%; mice had free access to food and water.
