R26rtdtomato tdtomato reporter

The R26R^{tdTomato/tdTomato} reporter (strain 007914), C57BL/6J (in the study referred to as WT; stock number 000664), and B6;129-Gt(ROSA)26Sor^{tm5(CAG–Sun1/sfGFP)Nat}/J (6 (link)) (referred to as Rosa26-SunTag; stock number 021039) mice were obtained from the Jackson Laboratory. We used previously characterized KI-Cre driver lines that label the SAN (23 (link)) (Shox2^KI–Cre), AVN (4 (link)) (Gjd3^KI–Cre), and VCS (24 (link)) (Cntn2^KI–Cre).

All animal experiments were approved by the Institutional Animal Care and Use Committee (IACUC) at UT Southwestern Medical Center and conformed to the National Institutes of Health (NIH) mandate for the care and use of laboratory animals. The R26R^{tdTomato/tdTomato} reporter (Strain number 007914), Wt1^GFPCre (stock number 010911), Nkx2-5^IRES-Cre (stock number 024637), C57BL/6J (in the study referred to as Wild type or WT) (stock number 000664), and B6;129-Gt(ROSA)26Sor^{tm5(CAG-Sun1/sfGFP)Nat}/J (in the study referred to as Rosa26-Sun1-sfGFP-myc-Tag) (stock number 021039) mice were obtained from the Jackson Laboratory (Bar Harbor, ME).

The FLP deleter strain (Strain number 009086) [24 (link)] and R26R^{tdTomato/tdTomato} reporter (Strain number 007914) [25 (link)] mice were obtained from the Jackson Laboratory (Bar Harbor, ME). For identification of the FLP allele and the R26R allele, we used two distinct primer sets (labelled Flp and R26R) which are enlisted in S1 Table. The newly generated KI reporter strain was maintained in a C57BL/6 background. All experimental procedures with animals were approved by the Institutional Animal Care and Use Committee at UT Southwestern Medical Center. All mice were euthanized using methods in accordance with the Panel on Euthanasia of the American Veterinary Medical Association. Briefly, mice were euthanized by CO2 inhalation, and a secondary method, such as cervical dislocation or decapitation, was used to confirm death in the animal.