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Connexin35 mediates electrical transmission at mixed synapses on Mauthner cells
Summary
Goldfish Mauthner cell synapses use connexin35 (Cx35) for electrical transmission. NMDA receptors regulate these Cx35 gap junctions, suggesting plasticity in electrical synapses.
Area of Science:
- Neuroscience
- Cell Biology
- Synaptic Plasticity
Background:
- Auditory afferents form mixed (electrical/chemical) synapses on goldfish Mauthner cells.
- These synapses allow correlation of physiological, biochemical, and ultrastructural data.
- Connexin35 (Cx35) is the fish ortholog of mammalian connexin36, crucial for neuronal electrical coupling.
Purpose of the Study:
- Identify the connexin protein at goldfish Mauthner cell mixed synapses.
- Investigate the role of NMDA receptors in modulating these electrical synapses.
- Determine the prevalence and potential plasticity of connexin35-mediated electrical transmission.
Main Methods:
- Confocal microscopy to visualize receptor subunits.
- Freeze-fracture replica immunogold labeling (FRIL) to identify proteins at synapses.
- Combined FRIL and confocal microscopy for correlative ultrastructural and molecular analysis.
Main Results:
- Gap junctions at these synapses contain connexin35 (Cx35).
- The NR1 subunit of the NMDA glutamate receptor is present at these mixed synapses.
- NR1 subunits are localized near Cx35-containing gap junction plaques.
Conclusions:
- Connexin35 mediates electrical transmission at goldfish Mauthner cell synapses.
- NMDA receptors are strategically located to modulate Cx35 gap junction conductance.
- Plasticity mechanisms at these identified junctions may be relevant to mammalian electrical synapses.