Figure 5. Comparison of the expression of photoreceptor and Müller "markers" and housekeeping gene products

Photoreceptors are shown as closed bars, and Müller cells as open bars. Genes known to be expressed predominantly or exclusively in photoreceptor cells in vivo were detected in photoreceptors in all cases, but with different frequencies (e.g., phosducin, rhodopsin, ROM-1 and S-antigen were present in 80-100% of the rods, β-PDE and GCAP1-α in about 60% of the cells, and recoverin in fewer than 30% of the cells). Several of the molecules were never detected in Müller cells (β-PDE, GCAP1-α, recoverin, and rhodopsin), but phosducin, ROM-1 and S-antigen could be detected in 10-15% of the Müller cells studied. Several Müller cell markers were observed in 65-95% of the Müller cells; carbonic anhydrase was never observed in rod photoreceptors, while CRALPB, glutamine synthetase and vimentin were observed in approximately 5% of the rods. Housekeeping genes were detected in both Müller and photoreceptor cells. β-actin, however, was detectable in twice as many Müller cells as photoreceptors. GAPDH was detectable in over 80% of the cells in both cases, whereas ubiquitinC was detected in 40-50% of the cells, with the differences between cell types not being statistically significant. An asterisk (*) is used to indicate p<0.05, and a double asterisk (**) to indicate p<0.001. Error bars represent standard error of the mean (SEM).