@article {65657, title = {Growth cone-localized microtubule organizing center establishes microtubule orientation in dendrites.}, journal = {eLife}, volume = {9}, year = {2020}, month = {2020 Jul 13}, abstract = {

A polarized arrangement of neuronal microtubule arrays is the foundation of membrane trafficking and subcellular compartmentalization. Conserved among both invertebrates and vertebrates, axons contain exclusively {\textquoteright}plus-end-out{\textquoteright} microtubules while dendrites contain a high percentage of {\textquoteright}minus-end-out{\textquoteright} microtubules, the origins of which have been a mystery. Here we show that in the dendritic growth cone contains a non-centrosomal microtubule organizing center, which generates minus-end-out microtubules along outgrowing dendrites and plus-end-out microtubules in the growth cone. RAB-11-positive endosomes accumulate in this region and co-migrate with the microtubule nucleation complex γ-TuRC. The MTOC tracks the extending growth cone by kinesin-1/UNC-116-mediated endosome movements on distal plus-end-out microtubules and dynein clusters this advancing MTOC. Critically, perturbation of the function or localization of the MTOC causes reversed microtubule polarity in dendrites. These findings unveil the endosome-localized dendritic MTOC as a critical organelle for establishing axon-dendrite polarity.

}, issn = {2050-084X}, doi = {10.7554/eLife.56547}, author = {Liang, Xing and Kokes, Marcela and Fetter, Richard D and Sallee, Maria Danielle and Moore, Adrian W and Feldman, Jessica L and Shen, Kang} } @article {6502, title = {GFP Reconstitution Across Synaptic Partners (GRASP) defines cell contacts and synapses in living nervous systems.}, journal = {Neuron}, volume = {57}, year = {2008}, month = {2008 Feb 7}, pages = {353-63}, abstract = {

The identification of synaptic partners is challenging in dense nerve bundles, where many processes occupy regions beneath the resolution of conventional light microscopy. To address this difficulty, we have developed GRASP, a system to label membrane contacts and synapses between two cells in living animals. Two complementary fragments of GFP are expressed on different cells, tethered to extracellular domains of transmembrane carrier proteins. When the complementary GFP fragments are fused to ubiquitous transmembrane proteins, GFP fluorescence appears uniformly along membrane contacts between the two cells. When one or both GFP fragments are fused to synaptic transmembrane proteins, GFP fluorescence is tightly localized to synapses. GRASP marks known synaptic contacts in C. elegans, correctly identifies changes in mutants with altered synaptic specificity, and can uncover new information about synaptic locations as confirmed by electron microscopy. GRASP may prove particularly useful for defining connectivity in complex nervous systems.

}, keywords = {Animal, Animals, Behavior, Biological, Caenorhabditis elegans, Caenorhabditis elegans Proteins, Carrier Proteins, Cells, Cultured, Electron, Genetically Modified, Green Fluorescent Proteins, Microscopy, Models, Mutation, Nervous System, Neurons, Synapses}, issn = {0896-6273}, doi = {10.1016/j.neuron.2007.11.030}, author = {Feinberg, Evan H and Vanhoven, Miri K and Bendesky, Andres and Wang, George and Fetter, Richard D and Shen, Kang and Bargmann, Cornelia I} } @article {68488, title = {Single-synapse ablation and long-term imaging in live C. elegans.}, journal = {J Neurosci Methods}, volume = {173}, year = {2008}, month = {09/2008}, pages = {20-6}, abstract = {

Synapses are individually operated, computational units for neural communication. To manipulate physically individual synapses in a living organism, we have developed a laser ablation technique for removing single synapses in live neurons in C. elegans that operates without apparent damage to the axon. As a complementary technique, we applied microfluidic immobilization of C. elegans to facilitate long-term fluorescence imaging and observation of neuronal development. With this technique, we directly demonstrated the existence of competition between developing synapses in the HSNL motor neuron.

}, keywords = {Animals, Axons, Behavior, Animal, Caenorhabditis elegans, Diagnostic Imaging, Laser Therapy, Microfluidic Analytical Techniques, Movement, Neurons, Synapses, Time Factors}, issn = {0165-0270}, doi = {10.1016/j.jneumeth.2008.05.007}, author = {Allen, Peter B and Sgro, Allyson E and Chao, Daniel L and Doepker, Byron E and Scott Edgar, J and Shen, Kang and Chiu, Daniel T} }