SD-Rosa26-LSL-tdTomato Rat

This strain is a conditional red fluorescent reporter rat strain carrying the expression cassette of the red fluorescent protein reporter gene (tdTomato). In the absence of Cre recombinase, the expression termination element (loxP-Stop-loxP, LSL) upstream of the tdTomato gene expression cassette blocks tdTomato expression. When this rat is crossed with a rat expressing Cre recombinase, Cre-positive cells, and their downstream differentiated lineages in the offspring undergo Cre recombinase-mediated deletion of the expression termination element between loxP sites, thereby achieving conditional expression of tdTomato protein. Strong tdTomato red fluorescent signals can then be observed in the relevant tissues or cells using a fluorescent microscope.

By mating SD-Rosa26-LSL-tdTomato rats with tissue-specific or inducible Cre rats, highly selective and controllable tdTomato protein expression time and location can be achieved. Validation data showed that strong red fluorescent signals were detected in the brain, heart, liver, spleen, kidney, thymus, pancreas, small intestine, large intestine, muscle, toes, ear, and tail of SD-Rosa26-LSL-tdTomato rats after Cre recombinase induction. Therefore, SD-Rosa26-LSL-tdTomato rats can be used for research in cell lineage tracing and specific gene expression regulation. Before the introduction of Cre recombinase, there may be deficient levels of tdTomato expression leakage in SD-Rosa26-LSL-tdTomato rats. Still, the tdTomato expression level mediated by Cre recombinase is significantly higher than the leakage level before induction.