Figure 2. Pou4f2Cre recombination patterns. A: Diagram of the Ai9 Cre reporter construct. This fluorescent reporter is driven by the CAG promoter and is designed to transcribe
red fluorescent protein (RFP) after Cre-mediated recombination removes the transcription termination cassette. B: The cartoon diagram showing varying Cre-mediated recombination patterns, which were dependent upon the parent carrying Pou4f2Cre and the reporter. Bi: Ubiquitous production of RFP in offspring when Pou4f2Cre and Ai9 are carried by the sire. Bii–iv: Pou4f2Cre specific recombination was observed in offspring when the sire carries Pou4f2Cre and the dam carries Ai9 (ii), Pou4f2Cre and Ai9 are carried by the dam (iii), or Ai9 is carried by the sire and the dam carries Pou4f2Cre (iv). C–E: Images of cryosections and tissue biopsies (ear) that are counterstained with 4,6-diamidino-2-phenylindole (DAPI). C: No RFP was detected in mice that carried Ai9 only. D: Offspring with germline recombination. RFP was detected throughout all tissues. E: Offspring with Pou4f2Cre-specific recombination. RFP was detected in the retina, brain, intestine, heart, and gonads. Scale bars = 100 μm (retina-kidney,
scale bar in the retina image; ear punch, scale bar in the image).