Name: in vivo assessment of microtubule dynamics and orientation in caenorhabditis elegans neurons
Uploaded: 2021-11-20T13:00:00
Description: Watch this Scientific Journal Video about In vivo Assessment of Microtubule Dynamics and Orientation in Caenorhabditis elegans Neurons at JoVE.com

We thank Yishi Jin and Andrew Chisholm for the initial support and the strain used in the study. The bacterial strain OP50 was commercially availed from Caenorhabditis Genetics Center (CGC) funded by NIH Office of Research Infrastructure Programs (P40 OD010440). We also thank Dharmendra Puri for the standardization of the experimental procedures. The study is funded by the core grant of National Brain Research Centre (supported by Department of Biotechnology, Govt. of India), DBT/Wellcome Trust India Alliance Early Career Grant (Grant # IA/E/18/1/504331) to S.D., Wellcome Trust-DBT India Alliance Intermediate Grant (Grant # IA/I/13/1/500874) to A.G.-R and a grant from Science and Engineering Research Board (SERB: CRG/2019/002194) to A.G.-R.

1. Reporter strain: Culture and maintenance
NOTE: To measure the microtubule dynamics and orientation in the PLM neurons, we used the worm strain expressing EBP-2::GFP under the touch neuron specific promoter mec-4 (juIs338 allele)18,25,26. We use standard worm culture and maintenance methods for this strain27.
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Understanding the microtubule dynamics has been a key focus in the field of cytoskeletal research over the years. Microtubules undergo nucleation and catastrophe along with a continuous process of dynamic instability44,45,46,47. Much of this information has been obtained through in vitro assays like light scattering readouts of free vs polymerized tubulin, microtubu...

Neurons have an elaborate architecture with specialized compartments like dendrites, cell bodies, axons, and synapses. The neuronal cytoskeleton is constituted of the microtubules, microfilaments, and neurofilaments and their distinct organization supports the neuronal compartments structurally and functionally1,2,3,4,5,6,7,8,9,10. Over the years, microtubule organization has been identified as a key determinant of neuronal polarity and function. As neurons undergo structural remodeling during development or regeneration, the microtubule dynamics and orientation determine the identity, polarized transport, growth, and development of various neuronal compartments7. It is, therefore, imperative to assess the microtubule dynamics and orientation in vivo to correlate with the neuronal remodeling process.
Microtubules are composed of protofilaments of &#945; and &#946; Tubulin heterodimers with dynamic plus ends and relatively stable minus ends11,12. The discovery of the plus tip complex and associated end binding proteins have enabled a platform to assess the microtubule organization13. End binding proteins (EBP) transiently associate with the growing plus ends of the microtubule and their association dynamics are correlated to the growth of the microtubule protofilaments14,15. Due to frequent association and dissociation of plus tip complex with the microtubule, the point spread function of GFP-tagged EBP appears as a &#34;comet&#34; in a timelapse movie15,16. Since the pioneering observation in mammalian neurons16, end binding proteins tagged with fluorescent proteins have been used to determine microtubule dynamics across different model systems and neuron types17,18,19,20,21,22,23.
Due to its simple nervous system and transparent body, C. elegans has proven to be an excellent model system to study neuronal remodeling during development and regeneration in vivo. Here we describe methods to label, image, and analyze the microtubule dynamics and growth during the development and regeneration of touch neurons in C. elegans. Using genetically encoded EBP-2::GFP, we imaged the microtubules in the PLM neuron, which allowed us to determine the polarity of the microtubules in two different neurites of this neuron24. This method allows observation and quantification of the EBP comets as a measure of microtubule dynamics in different cellular contexts, for example, the local changes in microtubule behavior that initiates axon regeneration following axotomy can be assessed using our protocol. This assay can be adapted to investigate the regulation of microtubule dynamics in various cellular processes in diverse cell types and genetic backgrounds.

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	<tbody>
		<tr>
			<td>CZ18975 worm strain</td>
			<td>Yishi Jin lab</td>
			<td>CZ18975</td>
			<td>Generated by Anindya Ghosh-Roy</td>
		</tr>
		<tr>
			<td>Agarose</td>
			<td>Sigma</td>
			<td>A9539</td>
			<td>Mounting worms</td>
		</tr>
		<tr>
			<td>Coverslip (18 mm x 18 mm)</td>
			<td>Zeiss</td>
			<td>474030-9010-000</td>
			<td>Mounting worms</td>
		</tr>
		<tr>
			<td>Dry bath with heating block</td>
			<td>Neolab</td>
			<td></td>
			<td>Mounting worms</td>
		</tr>
		<tr>
			<td>Glass slides (35 mm x 25 mm)</td>
			<td>Blue Star</td>
			<td></td>
			<td>Mounting worms</td>
		</tr>
		<tr>
			<td>Polystyrene bead solution (4.55 x 10^13 particles/ml in aqueous medium with minimal surfactant)</td>
			<td>Polysciences Inc.</td>
			<td>00876</td>
			<td>Mounting worms</td>
		</tr>
		<tr>
			<td>Test tubes</td>
			<td></td>
			<td></td>
			<td>Mounting worms</td>
		</tr>
		<tr>
			<td>OP50 bacterial strain</td>
			<td>Caenorhabditis Genetics Center (CGC)</td>
			<td>OP50</td>
			<td>Worm handling</td>
		</tr>
		<tr>
			<td>60mm petri plates</td>
			<td>Praveen Scientific</td>
			<td>20440</td>
			<td>Worm handling</td>
		</tr>
		<tr>
			<td>Aspirator/Capillary</td>
			<td>VWR</td>
			<td>53432-921</td>
			<td>Worm handling</td>
		</tr>
		<tr>
			<td>Incubator</td>
			<td>Panasonic</td>
			<td>MIR554E</td>
			<td>Worm handling</td>
		</tr>
		<tr>
			<td>Platinum wire</td>
			<td></td>
			<td></td>
			<td>Worm handling</td>
		</tr>
		<tr>
			<td>Stereomicroscope with fluorescence attachment</td>
			<td>Leica</td>
			<td>M165FC</td>
			<td>Worm handling</td>
		</tr>
		<tr>
			<td>0.3% Sodium Chloride</td>
			<td>Sigma</td>
			<td>71376</td>
			<td>Nematode Growth Medium</td>
		</tr>
		<tr>
			<td>0.25% Peptone</td>
			<td>T M Media</td>
			<td>1506</td>
			<td>Nematode Growth Medium</td>
		</tr>
		<tr>
			<td>10mg/mL Cholesterol</td>
			<td>Sigma</td>
			<td>C8667</td>
			<td>Nematode Growth Medium</td>
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		<tr>
			<td>1mM Calcium chloride dihydrate</td>
			<td>Sigma</td>
			<td>223506</td>
			<td>Nematode Growth Medium</td>
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		<tr>
			<td>1mM Magnesium sulphate heptahydrate</td>
			<td>Sigma</td>
			<td>M2773</td>
			<td>Nematode Growth Medium</td>
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		<tr>
			<td>2% Agar</td>
			<td>T M Media</td>
			<td>1202</td>
			<td>Nematode Growth Medium</td>
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		<tr>
			<td>25mM Monobasic Potassium dihydrogen phosphate</td>
			<td>Sigma</td>
			<td>P9791</td>
			<td>Nematode Growth Medium</td>
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		<tr>
			<td>0.1M Monobasic Potassium dihydrogen phosphate</td>
			<td>Sigma</td>
			<td>P9791</td>
			<td>1X M9 buffer</td>
		</tr>
		<tr>
			<td>0.04M Sodium chloride</td>
			<td>Sigma</td>
			<td>71376</td>
			<td>1X M9 buffer</td>
		</tr>
		<tr>
			<td>0.1M Ammonium chloride</td>
			<td>Fisher Scientific</td>
			<td>21405</td>
			<td>1X M9 buffer</td>
		</tr>
		<tr>
			<td>0.2M Dibasic Disodium hydrogen phosphate heptahydrate</td>
			<td>Sigma</td>
			<td>S9390</td>
			<td>1X M9 buffer</td>
		</tr>
		<tr>
			<td>Glass bottles</td>
			<td>Borosil</td>
			<td></td>
			<td>Buffer storage</td>
		</tr>
		<tr>
			<td>488 nm laser</td>
			<td>Zeiss</td>
			<td></td>
			<td>Imaging</td>
		</tr>
		<tr>
			<td>5X objective</td>
			<td>Zeiss</td>
			<td></td>
			<td>Imaging</td>
		</tr>
		<tr>
			<td>63X objective</td>
			<td>Zeiss</td>
			<td></td>
			<td>Imaging</td>
		</tr>
		<tr>
			<td>Camera</td>
			<td>Photometrics</td>
			<td>Evolve 512 Delta</td>
			<td>Imaging</td>
		</tr>
		<tr>
			<td>Computer system for Spinning Disk unit</td>
			<td>HP</td>
			<td>Intel &#174; Xeon CPU E5-2623 3.00GHz</td>
			<td>Imaging</td>
		</tr>
		<tr>
			<td>Epifluorescence microscope</td>
			<td>Zeiss</td>
			<td>Observer.Z1</td>
			<td>Imaging</td>
		</tr>
		<tr>
			<td>Halogen lamp</td>
			<td>Zeiss</td>
			<td></td>
			<td>Imaging</td>
		</tr>
		<tr>
			<td>Mercury Arc Lamp</td>
			<td>Zeiss</td>
			<td></td>
			<td>Imaging</td>
		</tr>
		<tr>
			<td>Spinning Disk Unit</td>
			<td>Yokogawa</td>
			<td>CSU-X1</td>
			<td>Imaging</td>
		</tr>
		<tr>
			<td>ZEN2 software</td>
			<td>Zeiss</td>
			<td></td>
			<td>Imaging</td>
		</tr>
		<tr>
			<td>Image J (Fiji Version)</td>
			<td></td>
			<td></td>
			<td>Image analysis and processing</td>
		</tr>
		<tr>
			<td>Adobe Creative Cloud</td>
			<td>Adobe</td>
			<td></td>
			<td>Image analysis and processing</td>
		</tr>
		<tr>
			<td>Computer system for Image Analysis</td>
			<td>Dell</td>
			<td>Intel &#174; Core &#8482; i7-9700 CPU 3.00GHz</td>
			<td>Image processing/Representation</td>
		</tr>
	</tbody>
</table>

in vivo assessment of microtubule dynamics and orientation in caenorhabditis elegans neurons

In neurons, microtubule orientation has been a key assessor to identify axons that have plus-end out microtubules and dendrites that generally have mixed orientation. Here we describe methods to label, image, and analyze the microtubule dynamics and growth during the development and regeneration of touch neurons in C. elegans. Using genetically encoded fluorescent reporters of microtubule tips, we imaged the axonal microtubules. The local changes in microtubule behavior that initiates axon regeneration following axotomy can be quantified using this protocol. This assay is adaptable to other neurons and genetic backgrounds to investigate the regulation of microtubule dynamics in various cellular processes.

As a representative example, we have described in vivo observation of the EBP comets in the steady-state and regenerating axons of the PLM neurons. PLM neurons are located in the tail region of the worm with a long anterior process that forms a synapse and a short posterior process. PLM neurons grow in the anterior-posterior direction close to the epidermis and are responsible for the gentle touch sensation in the worms. Due to their simplified structure, and amenability to imaging and microsurgery, PLM neurons have been...

Watch this Scientific Journal Video about In vivo Assessment of Microtubule Dynamics and Orientation in Caenorhabditis elegans Neurons at JoVE.com

In vivo Assessment of Microtubule Dynamics and Orientation in Caenorhabditis elegans Neurons

A protocol for imaging the dynamic microtubules in vivo using fluorescently labeled End binding protein has been presented. We described the methods to label, image, and analyze the dynamic microtubules in the Posterior lateral microtubule (PLM) neuron of C. elegans.

In vivo Assessment of Microtubule Dynamics and Orientation in Caenorhabditis elegans Neurons

In neurons, microtubule orientation has been a key assessor to identify axons that have plus-end out microtubules and dendrites that generally have mixed ...

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