Figure 1.

Generation and phenotypes of ^cKif3a^+/− and ^cKif3a^−/− mice. A, Generation of cone-specific Kif3a knock-outs (^cKif3a^−/−) by mating of Kif3a^flox/flox mice with transgenic mice expressing Cre recombinase under the control of the human red/green opsin (Hrgp) promoter. a, Diagram of exon 1 and exon 2 of the Kif3a gene; b, the floxed gene; c, the targeted gene with a deletion of exon 2. Primers 1–3 are used for genotyping the Kif3a alleles (Marszalek et al., 2000). B, Photopic ERG at P30. Black trace, The ^cKif3a^+/− response; red trace, the ^cKif3a^−/− response to a single flash (intensity, 25 db or 2.9 log cd s m⁻²). C, Confocal immunolocalization of ML-opsin and S-opsin in cone photoreceptors of 1-month-old ^cKif3a^+/− (a, c) and ^cKif3a^−/− mice (b, d). In a–d, sections were probed with anti-Cre antibody (green); in a and b, sections were probed with anti-ML-opsin (red), and in c and d, with anti S-opsin (red). Note that Cre recombinase is expressed in cone nuclei exclusively. ML-opsin and S-opsin are mislocalized to the inner segments, axons, and synaptic pedicles (white arrows) of ^cKif3a^−/− cones. Scale bar, 10 μm. IS, Inner segment; OPL, outer plexiform layer.