scholarly journals Diurnal Changes in Exocytosis and the Number of Synaptic Ribbons at Active Zones of an on-Type Bipolar Cell Terminal

2006 ◽  
Vol 96 (4) ◽  
pp. 2025-2033 ◽  
Author(s):  
Court Hull ◽  
Keith Studholme ◽  
Stephen Yazulla ◽  
Henrique von Gersdorff
Keyword(s):  
Synaptic Vesicle ◽  
Bipolar Cell ◽  
Bipolar Cells ◽  
Synaptic Ribbons ◽  
Diurnal Changes ◽  
Synaptic Vesicle Exocytosis ◽  
Pulse Ratio ◽  
Vesicle Exocytosis ◽  
Active Zones ◽  
Vesicle Pool

The number and morphology of synaptic ribbons at photoreceptor and bipolar cell terminals has been reported to change on a circadian cycle. Here we sought to determine whether this phenomenon exists at goldfish Mb-type bipolar cell terminals with the aim of exploring the role of ribbons in transmitter release. We examined the physiology and ultrastructure of this terminal around two time points: midday and midnight. Nystatin perforated-patch recordings of membrane capacitance ( Cm) revealed that synaptic vesicle exocytosis evoked by short depolarizations was reduced at night, even though Ca2+ currents were larger. The efficiency of exocytosis (measured as the Δ Cm jump per total Ca2+ charge influx) was thus significantly lower at night. The paired-pulse ratio remained unchanged, however, suggesting that release probability was not altered. Hence the decreased exocytosis likely reflects a smaller readily releasable vesicle pool at night. Electron microscopy of single sections from intact retinas averaged 65% fewer ribbons at night. Interestingly, the number of active zones did not change from day to night, only the probability of finding a ribbon at an active zone. Additionally, synaptic vesicle halos surrounding the ribbons were more completely filled at night when these on-type bipolar cells are more hyperpolarized. There was no change, however, in the physical dimensions of synaptic ribbons from day to night. These results suggest that the size of the readily releasable vesicle pool and the efficiency of exocytosis are reduced at night when fewer ribbons are present at bipolar cell terminal active zones.

scholarly journals Structural changes after transmitter release at the frog neuromuscular junction.

1981 ◽  
Vol 88 (3) ◽  
pp. 564-580 ◽  
Author(s):  
J E Heuser ◽  
T S Reese
Keyword(s):  
Plasma Membrane ◽  
Synaptic Vesicle ◽  
Structural Changes ◽  
Frog Neuromuscular Junction ◽  
Vesicle Membrane ◽  
Intramembrane Particles ◽  
Synaptic Vesicle Exocytosis ◽  
Quick Freezing ◽  
Vesicle Exocytosis ◽  
Active Zones

The sequence of structural changes that occur during synaptic vesicle exocytosis was studied by quick-freezing muscles at different intervals after stimulating their nerves, in the presence of 4-aminopyridine to increase the number of transmitter quanta released by each stimulus. Vesicle openings began to appear at the active zones of the intramuscular nerves within 3-4 ms after a single stimulus. The concentration of these openings peaked at 5-6 ms, and then declined to zero 50-100 ms late. At the later times, vesicle openings tended to be larger. Left behind at the active zones, after the vesicle openings disappeared, were clusters of large intramembrane particles. The larger particles in these clusters were the same size as intramembrane particles in undischarged vesicles, and were slightly larger than the particles which form the rows delineating active zones. Because previous tracer work had shown that new vesicles do not pinch off from the plasma membrane at these early times, we concluded that the particle clusters originate from membranes of discharged vesicles which collapse into the plasmalemma after exocytosis. The rate of vesicle collapse appeared to be variable because different stages occurred simultaneously at most times after stimulation; this asynchrony was taken to indicate that the collapse of each exocytotic vesicle is slowed by previous nearby collapses. The ultimate fate of synaptic vesicle membrane after collapse appeared to be coalescence with the plasma membrane, as the clusters of particles gradually dispersed into surrounding areas during the first second after a stimulus. The membrane retrieval and recycling that reverse this exocytotic sequence have a slower onset, as has been described in previous reports.

scholarly journals Complexin-1 regulated transition in the assembly of single neuronal SNARE complex

2021 ◽  
Author(s):  
Hao Tongrui ◽  
Feng Nan ◽  
Gong Fan ◽  
Liu Jiaquan ◽  
Lu Ma ◽  
...  
Keyword(s):  
Synaptic Vesicle ◽  
Molecular Mechanism ◽  
Optical Tweezers ◽  
Neurotransmitter Release ◽  
Snare Complex ◽  
Snare Proteins ◽  
Synaptic Vesicle Exocytosis ◽  
Sensitive Factor ◽  
Vesicle Exocytosis ◽  
Vesicle Pool

Neurotransmitter release is mediated by the synaptic vesicle exocytosis. Important proteins in this process have been identified including the molecular machine Synaptic-soluble N-ethylmaleimide-sensitive factor attachment receptor (SNARE) proteins, and other regulators. Complexin (Cpx) is one of the vital regulators in this process. The functions of Cpx are proposed to maintain a proper primed vesicle pool by preventing its premature depletion, which facilitates the vesicle fusion in the presence of Ca2+. However, the molecular mechanism remains unclear. Using dual-trap optical tweezers, we detected the interaction of complexin-1 (CpxI) with SNARE. We found that the CpxI stabilizes partially folded SNARE complexes by competing with C-terminal of Vamp protein and interacting with the C-terminal of t-SNARE complex.

scholarly journals Otoferlin Depletion Results in Abnormal Synaptic Ribbons and Altered Intracellular Calcium Levels in Zebrafish

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Aayushi Manchanda ◽  
Paroma Chatterjee ◽  
Josephine A. Bonventre ◽  
Derik E. Haggard ◽  
Katie S. Kindt ◽  
...  
Keyword(s):  
Hair Cell ◽  
Synaptic Vesicle ◽  
Hair Cells ◽  
Calcium Binding ◽  
Synaptic Ribbons ◽  
Vesicle Recycling ◽  
Synaptic Vesicle Exocytosis ◽  
Expression Of Genes ◽  
Vesicle Exocytosis ◽  
The Impact

Abstract The protein otoferlin plays an essential role at the sensory hair cell synapse. Mutations in otoferlin result in deafness and depending on the species, mild to strong vestibular deficits. While studies in mouse models suggest a role for otoferlin in synaptic vesicle exocytosis and endocytosis, it is unclear whether these functions are conserved across species. To address this question, we characterized the impact of otoferlin depletion in zebrafish larvae and found defects in synaptic vesicle recycling, abnormal synaptic ribbons, and higher resting calcium concentrations in hair cells. We also observed abnormal expression of the calcium binding hair cell genes s100s and parvalbumin, as well as the nogo related proteins rtn4rl2a and rtn4rl2b. Exogenous otoferlin partially restored expression of genes affected by endogenous otoferlin depletion. Our results suggest that in addition to vesicle recycling, depletion of otoferlin disrupts resting calcium levels, alters synaptic ribbon architecture, and perturbs transcription of hair cells specific genes during zebrafish development.

scholarly journals Role of specific presynaptic calcium channel subtypes in isoflurane inhibition of synaptic vesicle exocytosis in rat hippocampal neurones

2019 ◽  
Vol 123 (2) ◽  
pp. 219-227 ◽  
Author(s):  
Yuko Koyanagi ◽  
Christina L. Torturo ◽  
Daniel C. Cook ◽  
Zhenyu Zhou ◽  
Hugh C. Hemmings
Keyword(s):  
Calcium Channel ◽  
Synaptic Vesicle ◽  
Synaptic Vesicle Exocytosis ◽  
Vesicle Exocytosis ◽  
Presynaptic Calcium

scholarly journals SNARE Complex Oligomerization by Synaphin/Complexin Is Essential for Synaptic Vesicle Exocytosis

Cell ◽  
2001 ◽  
Vol 104 (3) ◽  
pp. 421-432 ◽  
Author(s):  
Hiroshi Tokumaru ◽  
Keiko Umayahara ◽  
Lorenzo L Pellegrini ◽  
Toru Ishizuka ◽  
Hideo Saisu ◽  
...  
Keyword(s):  
Synaptic Vesicle ◽  
Snare Complex ◽  
Synaptic Vesicle Exocytosis ◽  
Vesicle Exocytosis
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