Figure 6. Cre-dependent rAAV-mediated transgene delivery to retinal bipolar cells. A–B: The Cre-dependent rAAV2 virus vector cassettes that mediate the expression of a double-floxed inverted open-reading frame (DIO) encoding channelrhodopsin-2-mCherry (ChR2-mCherry) with ubiquitous neuronal promoter EF1α (A) and with Y444F capsid mutation and a ubiquitous viral promoter, cytomegalovirus (CMV; B). WPRE: woodchuck post-transcriptional regulatory element. hGHpA: a human growth hormone polyadenylation sequence. C–D: The expression of ChR2-mCherry mediated by virus vectors with the vector cassette shown in (A) in Pcp2-cre mice, viewed in retinal vertical section (C) and in the retinal whole mount with the focal plane at the GCL (D). E–F: The expression of ChR2-mCherry mediated by virus vectors with the vector cassette shown in (B) in Pcp2-cre mice, viewed in the retinal vertical section (E) and in the retinal whole mount with the focal plane at the INL (F). G–I: The expression of ChR2-mCherry infected by virus vectors with the vector cassette shown in (B) in Chx10-cre mice, viewed in the retinal vertical section (G and H) and in the retinal whole mount with the focal plane at the INL (I). J–L: In the vertical retinal sections, colabeling of GFP (J) and mCherry (K) of the virus infected retina in Chx10-cre mice. The overlay of J and K is shown in L. The double-positive bipolar cells are marked with arrowheads. Scale bars represent 25 µm in C, E, G, H, and J–L and 100 µm in D, F, and I.