Xenbase Image ID: 146115

Figure 4. The retrograde trafficking of opsin in rod photoreceptors during early development (6–8 dpf). A: A diagram to define the terms used for the analysis. The sample diagram is about the normalized intensities of old and new Opsin-Dend2 (2 days after photoconversion at 6 dpf) along the longitudinal axis of the OS. Crosspoint represents the point where disks with intensity profiles of old and new Opsin-Dend2 intersect. DR represents the distance between the crosspoint and the point where the level of old red Opsin-Dend2 became lower than 2%, in the direction towards where the new disks are being added. WG represents the width of the newly synthesized disks measured by the distance from the crosspoint to the point where the level of new green Opsin-Dend2 became lower than 2%. DG represents the distance between the crosspoint and the first appreciable peak of green. B: Shift of DR and WG over time after photoconversion. The distance of old Opsin-Dend2 trafficking back into new disks increased with the growth of new disks. Note: While images were captured starting from 0 hour, neither DR nor WG are definable at 0 hour and hence not included in this graph. C: Red Opsin-Dend2 concentrations in the disks from the crosspoint to the base of the OS (formed after photoconversion) were normalized to the concentration at the crosspoint. Left; the intensity–distance relationships were fitted to single exponential functions, and plotted on a linear scale graph for each time point after photoconversion. Right; the intensity–distance relationships were fitted to single exponential functions and plotted on a semilog graph. The concentration of red Opsin-Dend2 in new disks at the same distance (e.g., 1 μm) from the crosspoint increased with the increase in time after photoconversion. The data points from 0–2 μm were used for these analyses. The data points are represented by mean ± SE. D: Median of DG at different times after photoconversion. DG increased over time, suggestive of retrograde trafficking of green Opsin-Dend2 at the red–green interface. E: The slope of green Opsin-Dend2, around the crosspoint, was calculated at different timepoints after photoconversion. The slope decreased and the gradient of green Opsin-Dend2 became shallower over time. These time-dependent changes indicate the retrograde trafficking of Opsin-Dend2 at the red–green interface. In B,D,E, boxplots are shown with each IQR enclosed by colored boxes and median values indicated with white lines. The ends of whiskers represent the 5th and 95th percentiles. Outliers were omitted for clarity. ***P < 0.001 by the Mann–Whitney Rank Sum Test. ns = not significant. For 0 hour, 4 hours, 8 hours, and 1 day after photoconversion, n = 20 rods from three tadpoles were analyzed. For 2 days after photoconversion, n = 30 rods from five tadpoles were analyzed. Image published in: Tian G et al. (2014) Copyright © 2014. Image reproduced with permission of the Publisher, John Wiley & Sons. Larger Image Printer Friendly View

Return to previous page