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Dimitri M Kullmann & Kirill Volynski - Jeffrey Diamond Collaroration

Title: Mapping out neuronal ion channels in the brain and retina

UCL Supervisor: Dimitri M Kullmann, Ph.D. and Kirill Volynski, Ph.D. , UCL Institute of Neurology
NIH Supervisor: Jeffery Diamond, Ph.D., Synaptic Physiology Section, NINDS

Background

A major obstacle to understanding how neurons integrate signals and release neurotransmitters is that we have only a relatively limited knowledge of the distribution of different ion channels on their surface. Existing knowledge mainly comes from tissue preparations that disrupt cellular integrity, such as synaptosomes, or from fixed or frozen samples, in which ion channels do not function. A potentially powerful new approach to study the sub-­‐cellular distribution of ion channels in living neurons is scanning ion conductance microscopy, in which a patch-­‐clamp pipette can be used both to map out the fine structure of a single cell in vitro and to record from or activate ion channels at sub-­‐micron resolution.

Methods

The project will use a combination of scanning ion conductance and epifluorescence microscopy to identify cell bodies, neurites and presynaptic specializations in retinas and cortical neurons in vitro. Synaptic vesicles will be labeled with amphiphilic dyes, and patch-­‐clamp electrophysiology will be used to record from ion channels in identified subcellular compartments. Agonists or permeating ions can also be delivered via the pipette to complement the optical and electrophysiological data to establish how different channels are distributed.

References

Novak P et al. (2009). Nanoscale live-­‐cell imaging using hopping probe ion conductance microscopy. Nat Methods. 6:279-­‐81.

Ruiz A, Campanac E, Scott RS, Rusakov DA, Kullmann DM (2010). Presynaptic GABAA receptors enhance transmission and LTP induction at hippocampal mossy fiber synapses. Nat Neurosci. 13(4):431-­‐8.

Zhang J, Diamond JS (2009). Subunit-­‐ and pathway-­‐specific localization of NMDA receptors and scaffolding proteins at ganglion cell synapses in rat retina. J Neurosci. 29(13):4274-­‐86.

Contact details:
Dimitri M Kullmann, Ph.D. - d.kullmann@ucl.ac.uk
Kirill Volynski, Ph.D. - k.volynski@ucl.ac.uk
Jeffery Diamond, Ph.D. - diamondj@ninds.nih.gov