Physical determinants of vesicle mobility and supply at a central synapse

Encoding continuous sensory variables requires sustained synaptic signalling. At several sensory synapses, rapid vesicle supply is achieved via highly mobile vesicles and specialized ribbon structures, but how this is achieved at central synapses without ribbons is unclear. Here we examine vesicle mobility at excitatory cerebellar mossy fibre synapses which sustain transmission over a broad frequency bandwidth. Fluorescent recovery after photobleaching in slices from VGLUT1Venus knock-in mice reveal 75% of VGLUT1-containing vesicles have a high mobility, comparable to that at ribbon synapses. Experimentally constrained models establish hydrodynamic interactions and vesicle collisions are major determinants of vesicle mobility in crowded presynaptic terminals. Moreover, models incorporating 3D reconstructions of vesicle clouds near active zones (AZs) predict the measured releasable pool size and replenishment rate from the reserve pool. They also show that while vesicle reloading at AZs is not diffusion-limited at the onset of release, diffusion limits vesicle reloading during sustained high-frequency signalling.

Download Full-text

Modes of Vesicle Retrieval at Ribbon Synapses, Calyx-Type Synapses, and Small Central Synapses

Journal of Neuroscience ◽

10.1523/jneurosci.3471-07.2007 ◽

2007 ◽

Vol 27 (44) ◽

pp. 11793-11802 ◽

Cited By ~ 62

Author(s):

L.-G. Wu ◽

T. A. Ryan ◽

L. Lagnado

Keyword(s):

Ribbon Synapses ◽

Central Synapses

Download Full-text

Diffusion-Limited Extraction of Organic Ions by a Track-Membrane Interfaced Vacuum Inlet

European Journal of Mass Spectrometry ◽

10.1255/ejms.543 ◽

2003 ◽

Vol 9 (3) ◽

pp. 187-193 ◽

Cited By ~ 2

Author(s):

V.V. Gridin ◽

T.K. Kim ◽

A. Bekkerman ◽

V. Bulatov ◽

K.-H. Jung ◽

...

Keyword(s):

Ambient Pressure ◽

High Mobility ◽

Solute Concentration ◽

Charged Species ◽

Ion Injection ◽

Diffusion Limited ◽

Track Membranes ◽

Charge Extraction ◽

Organic Solutions ◽

State Charge

Glycerol-wetted track membranes (polyethylene terephthalate) were used to interface a low-vacuum facility (∼ 10−3 Torr) to an ambient pressure liquid analyte. High-field charge extraction conditions were routinely maintained between the liquid samples and a grid collector. The latter was positioned just near to the vacuum-facing side of such membranes. Upon establishing a steady-state charge-extraction regime, the collector currents were monitored and recorded at various solute concentration levels. The collector currents, which depend on solute concentration, were found to agree with recent theoretical treatments of such processes. Both positively- and negatively-charged species from organic solutions were routinely extracted. Ion injection for the low- and the high-mobility species has favored the diffusion-limited and the evaporation-limited schemes, respectively. Variable concentrations of 1-pyrenoyl-methylpyridinium bromide as well as naphthylacetic and anthracenecarboxylic acids in glycerol were used.

Download Full-text

Decision letter: Physical determinants of vesicle mobility and supply at a central synapse

10.7554/elife.15133.032 ◽

2016 ◽

Keyword(s):

Central Synapse ◽

Vesicle Mobility

Download Full-text

Author response: Physical determinants of vesicle mobility and supply at a central synapse

10.7554/elife.15133.033 ◽

2016 ◽

Author(s):

Jason Seth Rothman ◽

Laszlo Kocsis ◽

Etienne Herzog ◽

Zoltan Nusser ◽

Robin Angus Silver

Keyword(s):

Author Response ◽

Central Synapse ◽

Vesicle Mobility

Download Full-text

Hydrodynamics govern the pre-fusion docking time of synaptic vesicles

Journal of The Royal Society Interface ◽

10.1098/rsif.2017.0818 ◽

2018 ◽

Vol 15 (138) ◽

pp. 20170818

Author(s):

Pankaj Singh ◽

Chung-Yuen Hui

Keyword(s):

Synaptic Vesicle ◽

Synaptic Vesicles ◽

Driving Force ◽

Lipid Membrane ◽

Synaptic Cleft ◽

Fusion Pore ◽

Ribbon Synapses ◽

Experimental Findings ◽

Synaptic Vesicle Fusion ◽

Ribbon Structures

Synaptic vesicle fusion is a crucial step in the neurotransmission process. Neurotransmitter-filled vesicles are pre-docked at the synapse by the mediation of ribbon structures and SNARE proteins at the ribbon synapses. An electrical impulse triggers the fusion process of pre-docked vesicles, leading to the formation of a fusion pore and subsequently resulting in the release of neurotransmitter into the synaptic cleft. In this study, a continuum model of lipid membrane along with lubrication theory is used to determine the traverse time of the synaptic vesicle under the influence of hydrodynamic forces. We find that the traverse time is strongly dependent on how fast the driving force decays or grows with closure of the gap between the vesicle and the plasma membrane. If the correct behaviour is chosen, the traverse time obtained is of the order of a few hundred milliseconds and lies within the experimentally obtained value of approximately 250 ms (Zenisek D, Steyer JA, Almers W. 2000 Nature 406 , 849–854 ( doi:10.1038/35022500 )). We hypothesize that there are two different force behaviours, which complies with the experimental findings of pre-fusion docking of synaptic vesicles at the ribbon synapses. The common theme in the proposed force models is that the driving force has to very rapidly increase or decrease with the amount of clamping.

Download Full-text

A TEM study of the effect of oxygen on nanocavity formation and precipitation in rapid - solidified Fe-16Ni-9Cr stainless steels

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100171237 ◽

1994 ◽

Vol 52 ◽

pp. 700-701

Author(s):

S. Wisutmethangoon ◽

T. F. Kelly ◽

J.E. Flinn

Keyword(s):

Stainless Steels ◽

High Mobility ◽

Hot Extrusion ◽

Extrusion Ratio ◽

Gas Atomization ◽

Cavity Formation ◽

Nucleation Sites ◽

Heat Treated ◽

Different Types ◽

Effect Of Oxygen

Vacancies are introduced into the crystal phase during quenching of rapid solidified materials. Cavity formation occurs because of the coalescence of the vacancies into a cluster. However, because of the high mobility of vacancies at high temperature, most of them will diffuse back into the liquid phase, and some will be lost to defects such as dislocations. Oxygen is known to stabilize cavities by decreasing the surface energy through a chemisorption process. These stabilized cavities, furthermore, act as effective nucleation sites for precipitates to form during aging. Four different types of powders with different oxygen contents were prepared by gas atomization processing. The atomized powders were then consolidated by hot extrusion at 900 °C with an extrusion ratio 10,5:1. After consolidation, specimens were heat treated at 1000 °C for 1 hr followed by water quenching. Finally, the specimens were aged at 600 °C for about 800 hrs. TEM samples were prepared from the gripends of tensile specimens of both unaged and aged alloys.

Download Full-text

The need of electron microscopy in the study of domains and domain walls in ferroelectrics

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100170487 ◽

1994 ◽

Vol 52 ◽

pp. 550-551

Author(s):

Wenwu Cao

Keyword(s):

Domain Wall ◽

Domain Walls ◽

High Mobility ◽

Continuum Theory ◽

Polarization Vector ◽

Ferroelectric Materials ◽

Dielectric Constants ◽

Nonlocal Coupling ◽

Cubic Symmetry ◽

Gradient Energy

Domain structures play a key role in determining the physical properties of ferroelectric materials. The formation of these ferroelectric domains and domain walls are determined by the intrinsic nonlinearity and the nonlocal coupling of the polarization. Analogous to soliton excitations, domain walls can have high mobility when the domain wall energy is high. The domain wall can be describes by a continuum theory owning to the long range nature of the dipole-dipole interactions in ferroelectrics. The simplest form for the Landau energy is the so called ϕ model which can be used to describe a second order phase transition from a cubic prototype,where Pi (i =1, 2, 3) are the components of polarization vector, α's are the linear and nonlinear dielectric constants. In order to take into account the nonlocal coupling, a gradient energy should be included, for cubic symmetry the gradient energy is given by,

Download Full-text