FXR1P colocalizes with ribosomes in clusters along the dendrite.

A. Immunostaining of dissociated hippocampal neurons at 14 days in vitro with anti-FXR1P (#ML13) and anti-P0 shows a high degree of colocalization between FXR1P and P0 (white signal). Scale bar = 10 µm. B. High magnification view of the dendritic segment outlined in A showing colocalization between FXR1P and P0 in clusters along the dendrite. Scale bar = 2.5 µm. C. Graph demonstrating the covariance in the fluorescence intensities of FXR1P and P0 along the dendritic segment traced in B. D, E. Example of the results obtained from the Intensity Correlation Analysis (ICA). Images showing FXR1P, P0 and merged staining (D). Arrows point to colocalized clusters of FXR1P/P0, whereas arrowheads point to bright FXR1P clusters lacking P0. Scale bar = 5 µm. In E, the fluorescence intensity of FXR1P and P0 was plotted against the Products of the Differences from the Mean (PDM) of that pixel. Pixels where fluorescence intensities are correlated are shown to the right of the red line; uncorrelated pixels are shown on the left. These graphs show that a large number of high intensity P0 and FXR1P pixels are correlated. However, a fraction of high intensity FXR1P pixels are not correlated with P0 intensity, whereas a fraction of low intensity P0 pixels are not correlated with FXR1P intensity. (Inset) Image showing the positive PDM produced using the ICA plugin in ImageJ. For clarity, only the PDMs for pixels with intensities above the mean are shown. An intensity lookup table has been applied to the image and is shown on the right. Scale bar = 5 µm.