Figure 5. Immunolabeling of opsins in Moorfields/Institute of Ophthalmology-Müller 1 (MIO-M1) cells. A: Labeling of blue opsin and melanopsin, respectively, in MIO-M1 cells. The cells were counterstained against glutamine synthetase (GS) and GFAP, respectively. Double labeling yielded a yellow-orange merge signal. B: Labeling of rhodopsin and red-green opsin, respectively, in MIO-M1 cells. The cells were counterstained against GFAP. C: Control culture of MIO-M1 cells that was stained with secondary antibodies (goat antirabbit IgG and goat antimouse IgG) and without primary antibodies. No nonspecific labeling was observed either, following incubation with goat antirat IgG (not shown). D: Immunostaining of HEK-293 cells against melanopsin, blue opsin, and red green opsin, respectively. The cells were counterstained against glutamine synthetase (GS). Cell nuclei were labeled with the DNA dye Hoechst 33258 (blue). Bars are 20 µm.