TY - JOUR
T1 - Analysis of Rod/Cone Gap Junctions from the Reconstruction of Mouse Photoreceptor Terminals
AU - Ishibashi, Munenori
AU - Keung, Joyce
AU - Morgans, Catherine W.
AU - Aicher, Sue A.
AU - Carroll, James R.
AU - Singer, Joshua H.
AU - Jia, Li
AU - Li, Wei
AU - Fahrenfort, Iris
AU - Ribelayga, Christophe P.
AU - Massey, Stephen C.
N1 - Publisher Copyright:
© 2022, eLife Sciences Publications Ltd. All rights reserved.
PY - 2022/4
Y1 - 2022/4
N2 - Electrical coupling, mediated by gap junctions, contributes to signal averaging, synchronization and noise reduction in neuronal circuits. In addition, gap junctions may also provide alternative neuronal pathways. However, because they are small and especially difficult to image, gap junctions are often ignored in large-scale 3D reconstructions. Here, we reconstruct gap junctions between photoreceptors in the mouse retina, using serial blockface-scanning electron microscopy (SBF-SEM), focused ion beam-scanning electron microscopy (FIB-SEM), and confocal microscopy for the gap junction protein Cx36. An exuberant spray of fine telodendria extends from each cone pedicle (including blue cones) to contact 40-50 nearby rod spherules at sites of Cx36 labeling, with approximately 50 Cx36 clusters per cone pedicle and 2-3 per rod spherule. We were unable to detect rod/rod or cone/cone coupling. Thus, rod/cone coupling accounts for nearly all gap junctions between photoreceptors. We estimate a mean of 86 Cx36 channels per rod/cone pair, which may provide a maximum conductance of ~ 1200 pS, if all gap junction channels were open. This is comparable to the maximum conductance previously measured between rod/cone pairs in the presence of a dopamine antagonist to activate Cx36, suggesting the open probability of gap junction channels can approach 100% under certain conditions.
AB - Electrical coupling, mediated by gap junctions, contributes to signal averaging, synchronization and noise reduction in neuronal circuits. In addition, gap junctions may also provide alternative neuronal pathways. However, because they are small and especially difficult to image, gap junctions are often ignored in large-scale 3D reconstructions. Here, we reconstruct gap junctions between photoreceptors in the mouse retina, using serial blockface-scanning electron microscopy (SBF-SEM), focused ion beam-scanning electron microscopy (FIB-SEM), and confocal microscopy for the gap junction protein Cx36. An exuberant spray of fine telodendria extends from each cone pedicle (including blue cones) to contact 40-50 nearby rod spherules at sites of Cx36 labeling, with approximately 50 Cx36 clusters per cone pedicle and 2-3 per rod spherule. We were unable to detect rod/rod or cone/cone coupling. Thus, rod/cone coupling accounts for nearly all gap junctions between photoreceptors. We estimate a mean of 86 Cx36 channels per rod/cone pair, which may provide a maximum conductance of ~ 1200 pS, if all gap junction channels were open. This is comparable to the maximum conductance previously measured between rod/cone pairs in the presence of a dopamine antagonist to activate Cx36, suggesting the open probability of gap junction channels can approach 100% under certain conditions.
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U2 - 10.7554/eLife.73039
DO - 10.7554/eLife.73039
M3 - Article
C2 - 35471186
AN - SCOPUS:85129175476
SN - 2050-084X
VL - 11
JO - eLife
JF - eLife
M1 - e73039
ER -