Target-dependent regulation of presynaptic calcium influx in an identified neuromuscular synapse in Helisoma trivolvis

dc.contributor.advisor Philip G. Haydon Funte, Lisa
dc.contributor.department Zoology and Genetics 2018-08-23T14:25:56.000 2020-06-30T07:03:09Z 2020-06-30T07:03:09Z Fri Jan 01 00:00:00 UTC 1993 1993
dc.description.abstract <p>The focus of these studies has been to determine whether contact with an appropriate muscle target can regulate presynaptic calcium handling. An identified neuromuscular synapse from the freshwater pond snail Helisoma trivolvis was reconstructed in cell culture, and used to investigate the effect of target contact on presynaptic calcium handling. Cholinergic buccal moto-neuron 19 (B19) forms chemical synapses with muscle fibers from its in vivo synaptic target, the supralateral radular tensor (SLT) muscle. The reconstruction of this synapse in culture has allowed for experimental control of the extracellular environment, as well as experimental control over the timing of neuron-muscle contact. This control has permitted high-resolution studies of neuromuscular synaptogenesis;Contact with muscle fibers from the SLT causes a rapid enhancement (within 30 minutes) of action potential-evoked calcium accumulation as well as elevate resting calcium levels in neurons B19 at sites of muscle contact. Application of the cAMP analog pCPTcAMP mimics the effect of muscle contact on both presynaptic calcium accumulation, and resting calcium level. Inhibition of the activity of presynaptic cAMP-dependent protein kinase by the synthetic peptide inhibitor IP[subscript]20 blocks both muscle-induced and pCPTcAMP-induced enhancement of calcium levels. Taken together, these data indicate that muscle contact activates presynaptic cAMP-dependent protein kinase to locally-enhance resting calcium levels and action potential-evoked calcium accumulation;Tyrosine kinase activity was also shown to be necessary for the enhancement of presynaptic calcium accumulation. Inhibition of tyrosine kinase activity was shown to block the induction of, and reverse expressed muscle-induced enhancement of calcium accumulation. Inhibition of tyrosine kinase activity had only a small effect on pCPTcAMP-induced enhancement of action potential-evoked calcium accumulation, as did the intrasomatic injection of the broad-based protein tyrosine phosphatase rrbPTP-1. This suggests that the action of tyrosine kinase is upstream of the action of cAMP-dependent protein kinase.</p>
dc.format.mimetype application/pdf
dc.identifier archive/
dc.identifier.articleid 11230
dc.identifier.contextkey 6386182
dc.identifier.s3bucket isulib-bepress-aws-west
dc.identifier.submissionpath rtd/10231
dc.language.iso en
dc.source.bitstream archive/|||Fri Jan 14 18:16:45 UTC 2022
dc.subject.disciplines Neuroscience and Neurobiology
dc.subject.disciplines Neurosciences
dc.subject.keywords Zoology and genetics
dc.subject.keywords Neuroscience
dc.title Target-dependent regulation of presynaptic calcium influx in an identified neuromuscular synapse in Helisoma trivolvis
dc.type article
dc.type.genre dissertation
dspace.entity.type Publication
relation.isOrgUnitOfPublication 4a2929da-5374-4338-b62f-f5fd9e156ef9 Neuroscience dissertation Doctor of Philosophy
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