YFPγ2 fluorescence correlates with immunostaining of inhibitory postsynaptic, but not excitatory postsynaptic sites.

<p>(<b>A, C</b>) Vertical sections from P12 and P21 retinas immunostained with anti-GABA_AR α1 raised in different hosts. Upper panels are MIPs of image stacks of 15 µm total thickness. Lower panels show single optical sections (0.3 µm) within the stack at higher magnification. (<b>B, D</b>) (Upper-Left) Normalized fluorescence intensities for GABA_AR α1 ∼gp (green) and GABA_AR α1 ∼rb (red) are plotted against the vertical (z) depth of the IPL. (Upper-right) The correlation coefficient obtained from the cross-correlation of the two fluorescent channels plotted against depth of the IPL. (Lower panels) 2D cross-correlation plots for the entire depth of the IPL (region between red lines in upper-right). Correlation between the two channels decreases when one channel is shifted in ‘x and y’ (left plot) away from 0,0 or if one channel is rotated 180° (right plot) with respect to the other. (<b>E–H</b>) Cross-correlation analysis was also performed for vertical sections from P12 and P21 <i>Thy1-YFPγ2</i> retinas immunostained with anti-gephyrin, a protein found at inhibitory postsynaptic sites. (<b>I–L</b>) Similar plots for the excitatory postsynaptic marker, PSD95 at P12 and P21. Strong correlation between <i>Thy1-YFPγ2</i> fluorescence and inhibitory, but not excitatory, postsynaptic markers is present early in postnatal development. Scale bars 5 µm.