Analysis of rod/cone gap junctions from the reconstruction of mouse photoreceptor terminals
- University of Texas at Houston, United States
- Oregon Health & Science University, United States
- University of Maryland, College Park, United States
- National Eye Institute, National Institutes of Health, United States
Abstract
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.
Data availability
All the data used to create the figures in the manuscript have been provided as source data files for Figures 2, 3, 4, 5 and 8.The following data sets were generated.Ishibashi M, Keung J, Ribelayga CP, Massey SC (2018) Confocal imaging of the outer plexiform layer in mouse retina. Collection ID: 30675648bee2309e, URL: https://download.brainimagelibrary.org/30/67/30675648bee2309e/In the public domain at BIL http://www.brainimagelibrary.org/index.htmlSinger JH (2018) SBF-SEM of mouse retina. eel001. URL: https://wklink.org/9712In the public domain at webKnossos https://webknossos.org/Morgan CW, Aicher SA, Carroll JR (2019) FIB-SEM of the outer plexiform layer in light-adapted mouse retina. EM1 and EM2, URL: https://bossdb.org/project/ishibashi2021In the public domain at BossDB https://bossdb.org/
Article and author information
Author details
Munenori Ishibashi
Christophe P Ribelayga
Funding
National Institute of Mental Health (RF1MH127343)
- Catherine W Morgans
- Sue A Aicher
- Christophe P Ribelayga
- Stephen C Massey
National Eye Institute (EY029408)
- Christophe P Ribelayga
- Stephen C Massey
National Eye Institute (EY017836)
- Joshua H Singer
National Institute of Neurological Disorders and Stroke (P30NS061800)
- Sue A Aicher
National Eye Institute (P30EY028102)
- Stephen C Massey
The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.
Ethics
Animal experimentation: All animal procedures were reviewed and approved by the Animal Welfare Committee at the University of Texas Health Science Center at Houston (AWC-20-0138) or by our collaborators' local Institutional Animal Care and Use Committees.
Copyright
This is an open-access article, free of all copyright, and may be freely reproduced, distributed, transmitted, modified, built upon, or otherwise used by anyone for any lawful purpose. The work is made available under the Creative Commons CC0 public domain dedication.
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Analysis of rod/cone gap junctions from the reconstruction of mouse photoreceptor terminals
eLife 11:e73039.
https://doi.org/10.7554/eLife.73039
