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Probing Vesicles Dynamics in Single Hippocampal Synapses

Shtrahman, Matthew (2005) Probing Vesicles Dynamics in Single Hippocampal Synapses. Doctoral Dissertation, University of Pittsburgh. (Unpublished)

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The classic mode of communication between neurons occurs via chemical synapses. In this process, vesicles dock at the active zone and fuse with the cell membrane, emptying neurotransmitter into the synaptic cleft. This process is stochastic and the efficacy of synaptic communication depends on the availability and movement of vesicles. We use fluorescence correlation spectroscopy (FCS) and fluorescence recovery after photobleaching (FRAP) to study vesicle dynamics inside the synapses of cultured hippocampal neurons labeled with the fluorescent vesicle marker FM 1-43. These studies show that when the cell is electrically at rest, only a small population of vesicles is mobile, taking seconds to traverse the synapse. Applying the phosphatase inhibitor okadaic acid (OA) causes vesicles to diffuse freely, moving 30 times faster than vesicles in control synapses. In contrast, eliminating polymerized synaptic actin does not free vesicles. These results suggest that vesicles move sluggishly due to binding to structural proteins within the synapse, and that this binding is altered by phosphorylation. Motivated by these results, a model is constructed consisting of diffusing vesicles that bind reversibly within the synapse. This stick-and-diffuse model accounts for the FCS and FRAP data, and also predicts the well-known exponential refilling of the readily releasable pool. Our measurements suggest that the movement of vesicles to the active zone is the rate limiting step in this process.


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Item Type: University of Pittsburgh ETD
Status: Unpublished
CreatorsEmailPitt UsernameORCID
Shtrahman, Matthewmasst121@pitt.eduMASST121
ETD Committee:
TitleMemberEmail AddressPitt UsernameORCID
Committee ChairWu, Xiao-lunxlwu@pitt.eduXLWU
Committee MemberJasnow, Davidjasnow@pitt.eduJASNOW
Committee MemberBi, Guo-qianggqbi@pitt.eduGQBI
Committee MemberLevy, Jeremyjlevy@pitt.eduJLEVY
Committee MemberMeriney, Stevemeriney@bns.pitt.eduMERINEY
Date: 6 June 2005
Date Type: Completion
Defense Date: 28 March 2005
Approval Date: 6 June 2005
Submission Date: 18 April 2005
Access Restriction: No restriction; Release the ETD for access worldwide immediately.
Institution: University of Pittsburgh
Schools and Programs: Dietrich School of Arts and Sciences > Physics
Degree: PhD - Doctor of Philosophy
Thesis Type: Doctoral Dissertation
Refereed: Yes
Uncontrolled Keywords: fluorescence correlation spectroscopy (FCS); fluorescence recovery after photobleaching (FRAP); FM 1-43; readily releasable pool; refilling; synaptic vesicle
Other ID:, etd-04182005-160433
Date Deposited: 10 Nov 2011 19:38
Last Modified: 15 Nov 2016 13:40


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