Genetically Engineered Mouse Lines

Adult mice of both sexes were used. For compatibility with other projects in the laboratory, the PV-Cre (Jackson 017320) and DAT-Cre (Jackson 006660) used were also heterozygous for the FLP-dependent tdTomato reporter line Ai65F (Daigle et al., 2018 (link)); obtained in this case by crossing the Cre− and FLP-dependent tdTomato double-reporter line Ai65D (Madisen et al., 2015 (link); Jackson Laboratory 021875) to the Cre deleter line Meox2-Cre (Tallquist and Soriano, 2000 (link); Jackson Laboratory 003755), then breeding out the Meox2-Cre allele, resulting in a reporter line for which only FLP is required for expression of tdTomato). For those mice in which RVΔG-4FLPo was used, the reporter allele was necessary for reporting RV activity; for those in which RVΔG-4mCherry was used, the presence of this reporter allele was irrelevant. For Cre-negative control injections using RVΔG-4FLPo, the Ai65F line was used. For Cre-negative control injections using RVΔG-4mCherry, either Ai65F or the Cre-dependent reporter line Ai14 (Madisen et al., 2010 (link)) was used; in these cases, the presence of the reporter alleles was again irrelevant.