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Figure 6.
FAK protein expression is graded across the temporal-to-nasal axis of the RGC layer. a, b, Horizontal cryostat section through the left eye of a stage 35/36 Xenopus tadpole labeled with antibodies against Islet-1 to detect RGCs (a, arrowheads) and total FAK (b, arrowheads). Image of total FAK is presented as an inverted contrast grayscale image. Nasal is above and temporal below. Red dashed line indicates quadrants measured in e. Note higher FAK labeling in the temporal RGC quadrant. c, Two-color merge shows overlap of FAK labeling within the RGC layer. d, The average fluorescence intensity of FAK and Islet-1 labeling measured as a linescan across the temporal-to-nasal axis through the RGC layer of stage 35/36 retina (n = 8). Note that all FAK values were subtracted by the minimum intensity of FAK labeling measured at the nasal extreme. Both FAK and Islet-1 data points were fit to second-order polynomial regression curves (dashed lines). Note the intensity of FAK labeling decreases more robustly in the nasal half of the retina relative to the Islet-1 labeling. e, The intensity of FAK labeling in nasal versus temporal terminal quadrants of the RGC layer (red dashed lines in b), expressed relative to the nasal half. FAK expression is significantly higher in the temporal quadrant of the RGC layer at all stages examined. *p < 0.001, paired Student's t test. Scale bar, 50 μm. |
