Name: quantitative cell biology of neurodegeneration in drosophila through unbiased analysis of fluorescently tagged proteins using imagej
Uploaded: 2018-08-03T14:00:00
Description: Watch this Scientific Journal Video about Quantitative Cell Biology of Neurodegeneration in Drosophila Through Unbiased Analysis of Fluorescently Tagged Proteins Using ImageJ at JoVE.com

This work is supported by the Sheila and David Fuente Neuropathic Pain Research Program Graduate Fellowship (to J.M.B.), the Lois Pope LIFE Fellows Program (to C.L., Y.Z., and J.M.B.), the Snyder-Robinson Foundation Predoctoral Fellowship (to C.L.), the Dr. John T. Macdonald Foundation (to C.L.), contracts, grants from National Institutes of Health (NIH) HHSN268201300038C, R21GM119018, and R56NS095893 (to R.G.Z.), and by Taishan Scholar Project (Shandong Province, People&#39;s Republic of China) (to R.G.Z.).

1. Considerations and Preparations for Designing the Image Analysis Experiment
<ol>
	<li>Predetermine suitable anatomical, cellular, or subcellular markers to serve as landmarks for standardizing a region of interest (ROI) across different samples, for example 4&#39;,6-diamidino-2-phenylindole (DAPI), membrane markers, localized fluorescent protein, etc.</li>
	<li>Select a fluorescent marker that can delimit discrete puncta beyond background levels for the structure of interest. 
	NOTE: This protocol is o...

<ol>
	<li>Erkkinen, M. G., Kim, M. -. O., Geschwind, M. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Clinical+Neurology+and+Epidemiology+of+the+Major+Neurodegenerative+Diseases.">Clinical Neurology and Epidemiology of the Major Neurodegenerative Diseases.</a> Cold Spring Harbor perspectives in biology. , a033118 (2017).</li><li>Schindelin, J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Fiji:+an+open-source+platform+for+biological-image+analysis.">Fiji: an open-source platform for biological-image analysis.</a> Nature methods. 9 (7), 676-682 (2012).</li><li>Schneider, C. A., Rasband, W. S., Eliceiri, K. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=NIH+Image+to+ImageJ:+25+years+of+image+analysis.">NIH Image to ImageJ: 25 years of image analysis.</a> Nature methods. 9 (7), 671 (2012).</li><li>Mauvezin, C., Ayala, C., Braden, C. R., Kim, J., Neufeld, T. P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Assays+to+monitor+autophagy+in+Drosophila.">Assays to monitor autophagy in Drosophila.</a> Methods. 68 (1), 134-139 (2014).</li><li>Weiss, K. R., Kimura, Y., Lee, W. -. C. M., Littleton, J. T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Huntingtin+aggregation+kinetics+and+their+pathological+role+in+a+Drosophila+Huntington's+disease+model.">Huntingtin aggregation kinetics and their pathological role in a Drosophila Huntington's disease model.</a> Genetics. 190 (2), 581-600 (2012).</li><li>Babcock, D. T., Ganetzky, B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Transcellular+spreading+of+huntingtin+aggregates+in+the+Drosophila+brain.">Transcellular spreading of huntingtin aggregates in the Drosophila brain.</a> Proceedings of the National Academy of Sciences. 112 (39), E5427-E5433 (2015).</li><li>DeVorkin, L., Gorski, S. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Monitoring+autophagy+in+Drosophila+using+fluorescent+reporters+in+the+UAS-GAL4+system.">Monitoring autophagy in Drosophila using fluorescent reporters in the UAS-GAL4 system.</a> Cold Spring Harbor Protocols. 2014 (9), (2014).</li><li>Williamson, W. R., Hiesinger, P. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Preparation+of+developing+and+adult+Drosophila+brains+and+retinae+for+live+imaging.">Preparation of developing and adult Drosophila brains and retinae for live imaging.</a> Journal of visualized experiments: JoVE. (37), (2010).</li><li>Sweeney, S. T., Hidalgo, A., de Belle, J. S., Keshishian, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Dissection+of+adult+Drosophila+brains.">Dissection of adult Drosophila brains.</a> Cold Spring Harbor Protocols. (12), (2011).</li><li>Fox, C. H., Johnson, F. B., Whiting, J., Roller, P. P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Formaldehyde+fixation.">Formaldehyde fixation.</a> Journal of Histochemistry &amp; Cytochemistry. 33 (8), 845-853 (1985).</li><li>Lee, T., Luo, L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mosaic+analysis+with+a+repressible+cell+marker+(MARCM)+for+Drosophila+neural+development.">Mosaic analysis with a repressible cell marker (MARCM) for Drosophila neural development.</a> Trends in neurosciences. 24 (5), 251-254 (2001).</li><li>Fischbach, K. -. F., Dittrich, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+optic+lobe+of+Drosophila+melanogaster.+I.+A+Golgi+analysis+of+wild-type+structure.">The optic lobe of Drosophila melanogaster. I. A Golgi analysis of wild-type structure.</a> Cell and tissue research. 258 (3), 441-475 (1989).</li><li>Ruan, K., Zhu, Y., Li, C., Brazill, J. M., Zhai, R. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Alternative+splicing+of+Drosophila+Nmnat+functions+as+a+switch+to+enhance+neuroprotection+under+stress.">Alternative splicing of Drosophila Nmnat functions as a switch to enhance neuroprotection under stress.</a> Nature Communications. 6, 10057 (2015).</li><li>Zhai, R. G., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=NAD+synthase+NMNAT+acts+as+a+chaperone+to+protect+against+neurodegeneration.">NAD synthase NMNAT acts as a chaperone to protect against neurodegeneration.</a> Nature. 452 (7189), 887 (2008).</li><li>Li, C., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Spermine+synthase+deficiency+causes+lysosomal+dysfunction+and+oxidative+stress+in+models+of+Snyder-Robinson+syndrome.">Spermine synthase deficiency causes lysosomal dysfunction and oxidative stress in models of Snyder-Robinson syndrome.</a> Nat Commun. 8 (1), 1257 (2017).</li><li>Prokop, A., Meinertzhagen, I. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Development+and+structure+of+synaptic+contacts+in+Drosophila.">Development and structure of synaptic contacts in Drosophila.</a> Semin Cell Dev Biol. 17 (1), 20-30 (2006).</li><li>Maday, S., Holzbaur, E. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Autophagosome+biogenesis+in+primary+neurons+follows+an+ordered+and+spatially+regulated+pathway.">Autophagosome biogenesis in primary neurons follows an ordered and spatially regulated pathway.</a> Dev Cell. 30 (1), 71-85 (2014).</li><li>Mizushima, N., Yamamoto, A., Matsui, M., Yoshimori, T., Ohsumi, Y. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=In+vivo+analysis+of+autophagy+in+response+to+nutrient+starvation+using+transgenic+mice+expressing+a+fluorescent+autophagosome+marker.">In vivo analysis of autophagy in response to nutrient starvation using transgenic mice expressing a fluorescent autophagosome marker.</a> Molecular biology of the cell. 15 (3), 1101-1111 (2004).</li><li>Lee, S., Sato, Y., Nixon, R. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Primary+lysosomal+dysfunction+causes+cargo-specific+deficits+of+axonal+transport+leading+to+Alzheimer-like+neuritic+dystrophy.">Primary lysosomal dysfunction causes cargo-specific deficits of axonal transport leading to Alzheimer-like neuritic dystrophy.</a> Autophagy. 7 (12), 1562-1563 (2011).</li><li>Vincent, L., Soille, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Watersheds+in+digital+spaces:+an+efficient+algorithm+based+on+immersion+simulations.">Watersheds in digital spaces: an efficient algorithm based on immersion simulations.</a> IEEE Transactions on Pattern Analysis &amp; Machine Intelligence. (6), 583-598 (1991).</li><li>Najman, L., Schmitt, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Geodesic+saliency+of+watershed+contours+and+hierarchical+segmentation.">Geodesic saliency of watershed contours and hierarchical segmentation.</a> IEEE Transactions on pattern analysis and machine intelligence. 18 (12), 1163-1173 (1996).</li><li>Shiber, A., Breuer, W., Ravid, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Flow+cytometric+quantification+and+characterization+of+intracellular+protein+aggregates+in+yeast.">Flow cytometric quantification and characterization of intracellular protein aggregates in yeast.</a> Prion. 8 (3), 276-284 (2014).</li><li>Mizushima, N., Yoshimori, T., Levine, B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Methods+in+mammalian+autophagy+research.">Methods in mammalian autophagy research.</a> Cell. 140 (3), 313-326 (2010).</li></ol>

The protocol outlined here can be used to robustly and reproducibly quantitate cell biological processes visualized by fluorescence-based imaging. Biological context and technical limitations need to be carefully considered to guide the experimental design. Fluorescent markers of subcellular structures of interest, whether immunohistochemical, dye-based, or genetically expressed, need to be distinguishable above background by morphology and intensity. The UAS/GAL4 system is widely used to drive targeted gene exp...

Neurodegenerative diseases affect millions of people each year and the incidence is increasing with an aging population1. While each neurodegenerative disease has a unique etiology, aggregation of misfolded proteins and breakdown of the proteostasis network are common pathological hallmarks of many of these diseases. Elucidating how disruption of these fundamental and interrelated processes goes awry to contribute to neuronal dysfunction and cell death is critical for understanding neurodegenerative diseases as well as guiding therapeutic interventions. Fluorescence-based imaging allows for investigation of these complex and dynamic processes in neurons and has greatly contributed to our understanding of neuronal cell biology. Analysis of fluorescently tagged proteins is challenging, particularly when experiments are carried out in vivo, due to highly compact tissues, diverse cell types, and morphological heterogeneity. Manually assisted quantification is affordable and straightforward, but is often time-consuming and subject to human bias. Therefore, there is a need for unbiased, reproducible, and accessible approaches for extracting quantifiable data from imaging studies.
We have outlined a simple and adaptable workflow using Fiji/ImageJ, a powerful and freely accessible image processing software2,3, to extract quantitative data from fluorescence imaging studies in experimental models of neurodegeneration using Drosophila. By following this protocol to quantify protein aggregation and autophagic flux &#8212; two cell biological features that are highly relevant to neurodegenerative disease pathology &#8212; we demonstrated the sensitivity and reproducibility of this approach. Analysis of fluorescently tagged mutant huntingtin (Htt) proteins in the Drosophila optic lobe revealed the number, size, and intensity of protein aggregates. We visualized a tandem fluorescent reporter of autophagic flux within the Drosophila visual system, which displays different emission signals depending on the compartmental environment4. Ratiometric-based analysis of the tandem reporter allowed for a quantitative and comprehensive view of autophagy-lysosome flux from autophagosome formation, maturation, and transport to degradation in the lysosome, and additionally highlighted vulnerable compartments disrupted in neurodegenerative conditions. Importantly, in both analyses we implemented semi-automated thresholding and segmentation steps in our protocol to minimize unconscious bias, increase sampling power, and provide a standard to facilitate comparisons between similar studies. The straightforward workflow is intended to make powerful Fiji/ImageJ plugins (developed by computer scientists based on mathematic algorithms) more accessible to neurobiologists and the life sciences community at large.

<table border="0" cellpadding="0" cellspacing="0" width="1102">
	<tbody>
		<tr height="38">
			<td height="38" style="height:38px;width:347px;">SYLGARD(R) 184 Silicone Elastomer Kit</td>
			<td style="width:164px;">Dow Corning Corporation</td>
			<td style="width:243px;">PF184250</td>
			<td style="width:349px;">Dissection dish</td>
		</tr>
		<tr height="38">
			<td height="38" style="height:38px;width:347px;">Falcon 35 mm Not TC-Treated Easy-Grip Style Bacteriological Petri Dish</td>
			<td style="width:164px;">Corning</td>
			<td style="width:243px;">351008</td>
			<td style="width:349px;">Dissection dish</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:347px;">Dumont #5 Forceps</td>
			<td style="width:164px;">Fine Science Tools</td>
			<td style="width:243px;">11251-20</td>
			<td style="width:349px;">Dissection tool</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:347px;">Sodium Chloride</td>
			<td style="width:164px;">Sigma</td>
			<td style="width:243px;">S3014</td>
			<td style="width:349px;">PBS solution</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:347px;">Sodium Phosphate Dibasic&#160;</td>
			<td style="width:164px;">Sigma</td>
			<td style="width:243px;">S5136</td>
			<td style="width:349px;">PBS solution</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:347px;">Potassium Phosphate Monobasic</td>
			<td style="width:164px;">Sigma</td>
			<td style="width:243px;">P5655</td>
			<td style="width:349px;">PBS solution</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:347px;">Triton&#160;X-100</td>
			<td style="width:164px;">Sigma</td>
			<td style="width:243px;">T9284</td>
			<td style="width:349px;">Washing and antibody incubaton solution.&#160;</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:347px;">37% Formaldehyde</td>
			<td style="width:164px;">VWR</td>
			<td style="width:243px;">10790-710</td>
			<td style="width:349px;">Fixation</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:347px;">Disposable Microcentrifuge Tubes (0.5mL, blue)</td>
			<td style="width:164px;">VWR</td>
			<td style="width:243px;">89000-022</td>
			<td style="width:349px;">Fixation, washing, and antibody incubaton.&#160;</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:347px;">Plain and Frosted Micro Slides (25&#215;75mm)</td>
			<td style="width:164px;">VWR</td>
			<td style="width:243px;">48312-004</td>
			<td style="width:349px;">Slides for confocal imaging</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:347px;">Micro Cover Glasses, rectangular (22&#215;40mm)</td>
			<td style="width:164px;">VWR</td>
			<td style="width:243px;">48393-172</td>
			<td style="width:349px;">Slides for confocal imaging</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:347px;">Rubber Cement</td>
			<td style="width:164px;">Slime</td>
			<td style="width:243px;">1051-A</td>
			<td style="width:349px;">Mounting</td>
		</tr>
		<tr height="38">
			<td height="38" style="height:38px;width:347px;">VECTASHIELD Antifade Mounting Medium</td>
			<td style="width:164px;">Vector Laboratories, Inc.</td>
			<td style="width:243px;">H-1000</td>
			<td style="width:349px;">Mounting</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:347px;">Scotch Magic 810 Invisible Tape (19mm&#215;25.4m)</td>
			<td style="width:164px;">3M Company</td>
			<td style="width:243px;">810</td>
			<td style="width:349px;">Mounting</td>
		</tr>
		<tr height="38">
			<td height="38" style="height:38px;width:347px;">Normal Goat Serum</td>
			<td style="width:164px;">Thermo Fisher Scientific</td>
			<td style="width:243px;">PCN5000</td>
			<td style="width:349px;">Antibody incubaton</td>
		</tr>
		<tr height="76">
			<td height="76" style="height:76px;width:347px;">DAPI (4&#39;,6-Diamidino-2-Phenylindole, Dihydrochloride)&#160;</td>
			<td style="width:164px;">Thermo Fisher Scientific</td>
			<td style="width:243px;">D1306</td>
			<td style="width:349px;">Nucleic acid staining. Dissolve in deionized water to make a 5 mg/mL stock solution and store at -80&#176;C. Dilute to a working concentration of 10-20 &#956;g/mL in PBTx.</td>
		</tr>
		<tr height="38">
			<td height="38" style="height:38px;width:347px;">3.5X-90X Stereo Zoom Inspection Industrial Microscope</td>
			<td style="width:164px;">AmScope</td>
			<td style="width:243px;">SM-1BNZ</td>
			<td style="width:349px;">Dissection scope. Equipped with 6W LED Dual Gooseneck Illuminator</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:347px;">ImageJ/Fiji</td>
			<td style="width:164px;">NIH</td>
			<td style="width:243px;">v1.51u</td>
			<td style="width:349px;">With SCF_MPI_CBG plugins (version 1.1.2)</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:347px;">FV1000-IX81 Confocal-laser Scanning Microscope</td>
			<td style="width:164px;">Olympus</td>
			<td style="width:243px;"></td>
			<td style="width:349px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Recombinant Construct</td>
			<td>Bloomington Drosophila Stock Center</td>
			<td style="width:243px;">BL37749</td>
			<td style="width:349px;"></td>
		</tr>
	</tbody>
</table>

quantitative cell biology of neurodegeneration in drosophila through unbiased analysis of fluorescently tagged proteins using imagej

With the rising prevalence of neurodegenerative diseases, it is increasingly important to understand the underlying pathophysiology that leads to neuronal dysfunction and loss. Fluorescence-based imaging tools and technologies enable unprecedented analysis of subcellular neurobiological processes, yet there is still a need for unbiased, reproducible, and accessible approaches for extracting quantifiable data from imaging studies. We have developed a simple and adaptable workflow to extract quantitative data from fluorescence-based imaging studies using Drosophila models of neurodegeneration. Specifically, we describe an easy-to-follow, semi-automated approach using Fiji/ImageJ to analyze two cellular processes: first, we quantify protein aggregate content and profile in the Drosophila optic lobe using fluorescent-tagged mutant huntingtin proteins; and second, we assess autophagy-lysosome flux in the Drosophila visual system with ratiometric-based quantification of a tandem fluorescent reporter of autophagy. Importantly, the protocol outlined here includes a semi-automated segmentation step to ensure all fluorescent structures are analyzed to minimize selection bias and to increase resolution of subtle comparisons. This approach can be extended for the analysis of other cell biological structures and processes implicated in neurodegeneration, such as proteinaceous puncta (stress granules and synaptic complexes), as well as membrane-bound compartments (mitochondria and membrane trafficking vesicles). This method provides a standardized, yet adaptable reference point for image analysis and quantification, and could facilitate reliability and reproducibility across the field, and ultimately enhance mechanistic understanding of neurodegeneration.

Quantification of the number, area, and intensity of fluorescently tagged mutant Htt aggregates in the Drosophila optic lobe
To investigate misfolded protein aggregation in the central nervous system of a Drosophila model of Huntington&#39;s disease, RFP-tagged mutant human Htt with a non-pathological (UAS-RFP-hHttQ15) or pathological expansion (UAS-RFP-hHttQ138) and membrane GFP (UAS-mCD8::G...

Watch this Scientific Journal Video about Quantitative Cell Biology of Neurodegeneration in Drosophila Through Unbiased Analysis of Fluorescently Tagged Proteins Using ImageJ at JoVE.com

Quantitative Cell Biology of Neurodegeneration in Drosophila Through Unbiased Analysis of Fluorescently Tagged Proteins Using ImageJ

We have developed a simple and adaptable workflow to extract quantitative data from fluorescence-imaging-based cell biological studies of protein aggregation and autophagic flux in the central nervous system of Drosophila models of neurodegeneration.

Quantitative Cell Biology of Neurodegeneration in Drosophila Through Unbiased Analysis of Fluorescently Tagged Proteins Using ImageJ

With the rising prevalence of neurodegenerative diseases, it is increasingly important to understand the underlying pathophysiology that leads to neuronal ...

We developed this method to extract quantitative data from fluorescence-based imaging studies to extract complex and dynamic cell biological processes in Drosophila models of neurodegeneration. The main advantage of this technique is its an adaptable, semi-automated, image analysis workflow for minimizing selection bias, maximizing sampling power, and achieving reproducibility across the field. This approach can be extended for the analysis of other proteinaceous puncta and membrane-bound compartments implicated in neurodegeneration that ultimately will enhance our mechanistic understanding of neurodegenerative diseases.To keep the lamina intact during the dissection under a stereo microscope slide two forceps under the retina and gently tear through the middle of the eye to remove the retina. Keeping the forceps parallel to the lamina surface pull away any remaining retinal tissue attached to the lamina. Dissect three to five brains for each group and transfer the brains to a microcentrifuge tube containing an appropriate fixative for 15 minutes at room temperature with gentle rocking.After three 15-minute washes with PBS plus Triton X-100, or PBTx, replace the last wash with the primary antibody of interest diluted in PBTx with 5%normal goat serum for an overnight incubation in an aliquot mixer at four degrees Celsius. The next morning remove the excess antibody with three 15-minute washes in PBTx and incubate the brains in an appropriate secondary antibody diluted in PBTx with 5%normal goat serum for one hour at room temperature. At the end of the incubation wash the brains three times as demonstrated and place a drop of mounting medium between two pieces of clear tape in the center of one microscopy slide per tissue sample.Place the brains in the mounting media for one to two minutes. When the tissues become transparent use a pipette to carefully remove the mounting medium from each side. To image the stained tissues apply a drop of fresh mounting medium onto the brains and carefully overlay the samples with the a cover glass.Seal the cover glass edges with rubber cement and air dry the slides for 20 minutes at room temperature. Next view the specimen on the microscope and adjust the image detector controls on the fluorescence microscope to capture the highest signal-to-noise ratio in the highest a dynamic range of the specimen. Once the settings have been optimized view a specimen from another group to confirm the settings will be appropriate across the experiment.The first specimen can then be imaged taking care to save the image as a file type that can preserve metadata such as acquisition parameters and spatial calibration. To analyze the images open an image in Fiji select View Stack with Hyperstack from the Bio-formats Import Options dialog box and set the color mode to Grayscale. Identify an area based on the marker channels that can be used as a standardized region of interest across specimens using the C scroll bar to view the channels and the Z scroll bar to move through the focal planes.To simplify the image analysis generate a new image containing the channels and focal planes and select Image and Duplicate. Set the desired channels and slices and change the file name to reflect the selection. Manually select a standardized region of interest using a Selection Tool based on the previously determined selection criteria.Click Analyze, Tools, Region of Interest Manager, and Add to add the region of interest to the Region of Interest Manager. Then click More and Save and name the file to reflect the region of interest. For pre processing the images click Process in Filters and select an appropriate filter.Here select filter settings that reduce noise while preserving edges in order to aid in detection of the structures of interest during segmentation. With the pre processed image active in Fiji click SCF, Labeling, and Interactive H_Watershed. From the control panel adjust the Seed dynamics, Intensity threshold, and Peak flooding to optimize the segmentation.When the segmentation results have been optimized select Export Regions Mask and Export to generate a binary image of the watershed results. Open the saved standardized region of interest. From the Region of Interest Manager select the region of interest identifier to limit the feature extraction to the standardized region of interest in the image.With the region of interest active on the binary watershed mask select Analyze, Analyze Particles, and Add to Manager to extract the features to add a particle identifier for each structure delineated during the segmentation to the Region of Interest Manager. Then save the added particles taking care that the identifiers are deselected and that all of the particles are saved in a zip file. Now open the pre processed raw image and scroll to the channel used for capturing the structures of interest.Open the particles obtained from the feature extraction and select Show All in the Region of Interest Manager to overlay an outline of each particle onto the image. Click Analyze and Set Measurements and set the appropriate experimental measurements. Then from the Region of Interest Manager select Measure and copy and paste the results into an appropriate spreadsheet program for compilation and further calculations.Quantification of the number of semi-automatically segmented RFP huntingtin aggregates from standardized focal planes through the optic lobe of Drosophila reveals a diffuse expression of the non-pathogenic Huntington Q15 expansion in the accumulation of protein aggregates by the disease-causing Huntington Q138 expansion. Size and intensity profiles of all the aggregates from a standardized focal plane of five different optic lobes expressing Huntington Q138 illustrate the robustness and reproducibility of this workflow. When aggregates are over-exposed during image acquisition quantification of the size and number of aggregates is comparable to aggregates captured with ideal exposure.However the intensity of the over-exposed aggregates becomes a function of size as the saturated pixels exhibit the maximum intensity value. Visualization of mCherry and GFP intensity across several autophagy-related or Atg8 positive structures reveals differences in the reporter where the high intensity of both fluorophores indicates autophagosomes. High mCherry and low GFP indicates fusion with lysosome as GFP is quenched in this acidic compartment.And finally low mCherry reflects degradation within the lysosome. A scatterplot generated from the mean fluorophore intensity of each semi-automatically segmented mCherry Atg8 positive particle illustrates flux through the autophagy lysosome pathway that can be separated into discrete steps by quadrant analysis. While attempting this procedure it's important to remember that the user-defined parameters in image analysis steps are highly application dependent.So be careful to document the workflow to ensure consistency and comparability across specimens.

quantitative-cell-biology-neurodegeneration-drosophila-through

Research

JoVE Journal

Neuroscience

Assaying Locomotor, Learning, and Memory Deficits in Drosophila Models of Neurodegeneration

Advances in genetic methods have enabled the study of genes involved in human neurodegenerative diseases using Drosophila as a model system1. Most of these diseases, including Alzheimer's, Parkinson's and Huntington's disease are characterized by age-dependent deterioration in learning and memory functions and movement coordination2. Here we use behavioral assays, including the negative geotaxis assay3 and the aversive phototaxic suppression assay (APS assay)4,5, to show that some of the behavior characteristics associated with human neurodegeneration can be recapitulated in flies. In the negative geotaxis assay, the natural tendency of flies to move against gravity when agitated is utilized to study genes or conditions that may hinder locomotor capacities. In the APS assay, the learning and memory functions are tested in positively-phototactic flies trained to associate light with aversive bitter taste and hence avoid this otherwise natural tendency to move toward light. Testing these trained flies 6 hours post-training is used to assess memory functions. Using these assays, the contribution of any genetic or environmental factors toward developing neurodegeneration can be easily studied in flies.

Assaying Locomotor, Learning, and Memory Deficits in Drosophila Models of Neurodegeneration

Behavior assays for measuring locomotor functions, learning, and memory abilities in Drosophila.

Advances in genetic methods have enabled the study of genes involved in human neurodegenerative diseases using Drosophila as a model system1. Most of ...

Quantitative Analysis of Synaptic Vesicle Pool Replenishment in Cultured Cerebellar Granule Neurons using FM Dyes

After neurotransmitter release in central nerve terminals, SVs are rapidly retrieved by endocytosis. Retrieved SVs are then refilled with neurotransmitter and rejoin the recycling pool, defined as SVs that are available for exocytosis1,2. The recycling pool can generally be subdivided into two distinct pools - the readily releasable pool (RRP) and the reserve pool (RP). As their names imply, the RRP consists of SVs that are immediately available for fusion while RP SVs are released only during intense stimulation1,2. It is important to have a reliable assay that reports the differential replenishment of these SV pools in order to understand 1) how SVs traffic after different modes of endocytosis (such as clathrin-dependent endocytosis and activity-dependent bulk endocytosis) and 2) the mechanisms controlling the mobilisation of both the RRP and RP in response to different stimuli.
FM dyes are routinely employed to quantitatively report SV turnover in central nerve terminals3-8. They have a hydrophobic hydrocarbon tail that allows reversible partitioning in the lipid bilayer, and a hydrophilic head group that blocks passage across membranes. The dyes have little fluorescence in aqueous solution, but their quantum yield increases dramatically when partitioned in membrane9. Thus FM dyes are ideal fluorescent probes for tracking actively recycling SVs. The standard protocol for use of FM dye is as follows. First they are applied to neurons and are taken up during endocytosis (Figure 1). After non-internalised dye is washed away from the plasma membrane, recycled SVs redistribute within the recycling pool. These SVs are then depleted using unloading stimuli (Figure 1). Since FM dye labelling of SVs is quantal10, the resulting fluorescence drop is proportional to the amount of vesicles released. Thus, the recycling and fusion of SVs generated from the previous round of endocytosis can be reliably quantified.
Here, we present a protocol that has been modified to obtain two additional elements of information. Firstly, sequential unloading stimuli are used to differentially unload the RRP and the RP, to allow quantification of the replenishment of specific SV pools. Secondly, each nerve terminal undergoes the protocol twice. Thus, the response of the same nerve terminal at S1 can be compared against the presence of a test substance at phase S2 (Figure 2), providing an internal control. This is important, since the extent of SV recycling across different nerve terminals is highly variable11.
Any adherent primary neuronal cultures may be used for this protocol, however the plating density, solutions and stimulation conditions are optimised for cerebellar granule neurons (CGNs)12,13.

A live fluorescence imaging technique to quantify the replenishment and mobilisation of specific synaptic vesicle (SV) pools in central nerve terminals is described. Two rounds of SV recycling are monitored in the same nerve terminals providing an internal control.

After neurotransmitter release in central nerve terminals, SVs are rapidly retrieved by endocytosis.  Retrieved SVs are then refilled with ...

Spectral Confocal Imaging of Fluorescently tagged Nicotinic Receptors in Knock-in Mice with Chronic Nicotine Administration

Ligand-gated ion channels in the central nervous system (CNS) are implicated in numerous conditions with serious medical and social consequences. For instance, addiction to nicotine via tobacco smoking is a leading cause of premature death worldwide (World Health Organization) and is likely caused by an alteration of ion channel distribution in the brain1. Chronic nicotine exposure in both rodents and humans results in increased numbers of nicotinic acetylcholine receptors (nAChRs) in brain tissue1-3. Similarly, alterations in the glutamatergic GluN1 or GluA1 channels have been implicated in triggering sensitization to other addictive drugs such as cocaine, amphetamines and opiates4-6.

Consequently, the ability to map and quantify distribution and expression patterns of specific ion channels is critically important to understanding the mechanisms of addiction. The study of brain region-specific effects of individual drugs was advanced by the advent of techniques such as radioactive ligands. However, the low spatial resolution of radioactive ligand binding prevents the ability to quantify ligand-gated ion channels in specific subtypes of neurons. 

Genetically encoded fluorescent reporters, such as green fluorescent protein (GFP) and its many color variants, have revolutionized the field of biology7.By genetically tagging a fluorescent reporter to an endogenous protein one can visualize proteins in vivo7-10. One advantage of fluorescently tagging proteins with a probe is the elimination of antibody use, which have issues of nonspecificity and accessibility to the target protein. We have used this strategy to fluorescently label nAChRs, which enabled the study of receptor assembly using F&ouml;rster Resonance Energy Transfer (FRET) in transfected cultured cells11.More recently, we have used the knock-in approach to engineer mice with yellow fluorescent protein tagged &alpha;4 nAChR subunits (&alpha;4YFP), enabling precise quantification of the receptor ex vivo at submicrometer resolution in CNS neurons via spectral confocal microscopy12. The targeted fluorescent knock-in mutation is incorporated in the endogenous locus and under control of its native promoter, producing normal levels of expression and regulation of the receptor when compared to untagged receptors in wildtype mice. This knock-in approach can be extended to fluorescently tag other ion channels and offers a powerful approach of visualizing and quantifying receptors in the CNS.

In this paper we describe a methodology to quantify changes in nAChR expression in specific CNS neurons after exposure to chronic nicotine. Our methods include mini-osmotic pump implantation, intracardiac perfusion fixation, imaging and analysis of fluorescently tagged nicotinic receptor subunits from &alpha;4YFP knock-in mice (Fig. 1). We have optimized the fixation technique to minimize autofluorescence from fixed brain tissue.We describe in detail our imaging methodology using a spectral confocal microscope in conjunction with a linear spectral unmixing algorithm to subtract autofluoresent signal in order to accurately obtain &alpha;4YFP fluorescence signal. Finally, we show results of chronic nicotine-induced upregulation of &alpha;4YFP receptors in the medial perforant path of the hippocampus.

We have developed a novel technique of quantifying nicotinic acetylcholine receptor changes within subcellular regions of specific subtypes of CNS neurons to better understand the mechanisms of nicotine addiction by using a combination of approaches including fluorescent protein tagging of the receptor using the knock-in approach and spectral confocal imaging.

Ligand-gated ion channels in the central nervous system (CNS) are implicated in numerous conditions with serious medical and social consequences.  For ...

Quantitative Analysis of Climbing Defects in a Drosophila Model of Neurodegenerative Disorders

Locomotive defects resulting from neurodegenerative disorders can be a late onset symptom of disease, following years of subclinical degeneration, and thus current therapeutic treatment strategies are not curative. Through the use of whole exome sequencing, an increasing number of genes have been identified to play a role in human locomotion. Despite identifying these genes, it is not known how these genes are crucial to normal locomotive functioning. Therefore, a reliable assay, which utilizes model organisms to elucidate the role of these genes in order to identify novel targets of therapeutic interest, is needed more than ever. We have designed a sensitized version of the negative geotaxis assay that allows for the detection of milder defects earlier and has the ability to evaluate these defects over time. The assay is performed in a glass graduated cylinder, which is sealed with a wax barrier film. By increasing the threshold distance to be climbed to 17.5 cm and increasing the experiment duration to 2 min&#160;we have observed a greater sensitivity in detecting mild mobility dysfunctions. The assay is cost effective and does not require extensive training to obtain highly reproducible results. This makes it an excellent technique for screening candidate drugs in Drosophila mutants with locomotion defects.

We present an optimized inexpensive and reliable negative geotaxis assay in Drosophila melanogaster as a model for neurodegenerative disorders. Being more sensitive to mild locomotor defects, this assay will help screen for potential genetic interactions and drug targets.

Locomotive defects resulting from neurodegenerative disorders can be a late onset symptom of disease, following years of subclinical degeneration, and ...

In Vivo Gene Transfer to Schwann Cells in the Rodent Sciatic Nerve by Electroporation

The formation of the myelin sheath by Schwann cells (SCs) is essential for rapid conduction of nerve impulses along axons in the peripheral nervous system. SC-selective genetic manipulation in living animals is a powerful technique for studying the molecular and cellular mechanisms of SC myelination and demyelination in vivo. While knockout/knockin and transgenic mice are powerful tools for studying SC biology, these methods are costly and time consuming. Viral vector-mediated transgene introduction into the sciatic nerve is a simpler and less laborious method. However, viral methods have limitations, such as toxicity, transgene size constraints, and infectivity restricted to certain developmental stages. Here, we describe a new method that allows selective transfection of myelinating SCs in the rodent sciatic nerve using electroporation. By applying electric pulses to the sciatic nerve at the site of plasmid DNA injection, genes of interest can be easily silenced or overexpressed in SCs in both neonatal and more mature animals. Furthermore, this in vivo electroporation method allows for highly efficient simultaneous expression of multiple transgenes. Our novel technique should enable researchers to efficiently manipulate SC gene expression, and facilitate studies on SC development and function.

In Vivo Gene Transfer to Schwann Cells in the Rodent Sciatic Nerve by Electroporation

Here, we present an in vivo technique for gene transfer to Schwann cells (SCs) in the rodent sciatic nerve. This simple technique is useful for investigating signaling mechanisms involved in the development and maintenance of myelinating SCs.

The formation of the myelin sheath by Schwann cells (SCs) is essential for rapid conduction of nerve impulses along axons in the peripheral nervous ...

Mass Histology to Quantify Neurodegeneration in Drosophila

Progressive neurodegenerative diseases like Alzheimer&#39;s disease (AD) or Parkinson&#39;s disease (PD) are an increasing threat to human health worldwide. Although mammalian models have provided important insights into the underlying mechanisms of pathogenicity, the complexity of mammalian systems together with their high costs are limiting their use. Therefore, the simple but well-established Drosophila model-system&#160;provides an alternative for investigating the molecular pathways that are affected in these diseases. Besides behavioral deficits, neurodegenerative diseases are characterized by histological phenotypes such as neuronal death and axonopathy. To quantify neuronal degeneration and to determine how it is affected by genetic and environmental factors, we use a histological approach that is based on measuring the vacuoles in adult fly brains. To minimize the effects of systematic error and to directly compare sections from control and experimental flies in one preparation, we use the &#39;collar&#39; method for paraffin sections. Neurodegeneration is then assessed by measuring the size and/or number of vacuoles that have developed in the fly brain. This can either be done by focusing on a specific region of interest or by analyzing the entire brain by obtaining serial sections that span the complete head. Therefore, this method allows one to measure not only severe degeneration but also relatively mild phenotypes that are only detectable in a few sections, as occurs during normal aging.

Mass Histology to Quantify Neurodegeneration in Drosophila

Drosophila is widely used as a model system to study neurodegeneration. This protocol describes a method by which degeneration, as determined by vacuole formation in the brain, can be quantified. It also minimizes effects due to the experimental procedure by processing and sectioning control and experimental flies as one sample.

Progressive neurodegenerative diseases like Alzheimer&#39;s disease (AD) or Parkinson&#39;s disease (PD) are an increasing threat to human health ...

Using Linear Agarose Channels to Study Drosophila Larval Crawling Behavior

Drosophila larval crawling is emerging as a powerful model to study neural control of sensorimotor behavior. However, larval crawling behavior on flat open surfaces is complex,&#160;including: pausing, turning, and meandering. This complexity in the repertoire of movement hinders detailed analysis of the events occurring during a single crawl stride cycle. To overcome this obstacle, linear agarose channels were made that constrain larval behavior to straight, sustained, rhythmic crawling. In principle, because agarose channels and the Drosophila larval body are both optically clear, the movement of larval structures labeled by genetically-encoded fluorescent probes can be monitored in intact, freely-moving larvae. In the past, larvae were placed in linear channels and crawling at the level of whole organism, segment, and muscle were analyzed1. In the future, larvae crawling in channels can be used for calcium imaging to monitor neuronal activity. Moreover, these methods can be used with larvae of any genotype and with any researcher-designed channel. Thus the protocol presented below is widely applicable for studies using the Drosophila larva as a model to understand motor control.

Using Linear Agarose Channels to Study Drosophila Larval Crawling Behavior

The Drosophila larva is a powerful model system to study neural control of behavior. This publication describes the use of linear agarose channels to elicit sustained bouts of linear crawling and methods to quantify the dynamics of larval structures during repetitive crawling behavior.

Drosophila larval crawling is emerging as a powerful model to study neural control of sensorimotor behavior. However, larval crawling behavior on flat ...

Quantitative Analysis of Neuronal Dendritic Arborization Complexity in Drosophila

Dendrites are the branched projections of a neuron, and dendritic morphology reflects synaptic organization during the development of the nervous system. Drosophila larval neuronal dendritic arborization (da) is an ideal model for studying morphogenesis of neural dendrites and gene function in the development of nervous system. There are four classes of da neurons. Class IV is the most complex with a branching pattern that covers almost the entire area of the larval body wall. We have previously characterized the effect of silencing the Drosophila ortholog of SOX5 on class IV neuronal dendritic arborization complexity (NDAC) using four parameters: the length of dendrites, the surface area of dendrite coverage, the total number of branches, and the branching structure. This protocol presents the workflow of NDAC quantitative analysis, consisting of larval dissection, confocal microscopy, and image analysis procedures using ImageJ software. Further insight into da neuronal development and its underlying mechanisms will improve the understanding of neuronal function and provide clues about the fundamental causes of neurological and neurodevelopmental disorders.

Quantitative Analysis of Neuronal Dendritic Arborization Complexity in Drosophila

This protocol focuses on quantitative analysis of neuronal dendritic arborization complexity (NDAC) in Drosophila, which can be used for studies of dendritic morphogenesis.

Dendrites are the branched projections of a neuron, and dendritic morphology reflects synaptic organization during the development of the nervous system. ...

An Unbiased Approach of Sampling TEM Sections in Neuroscience

Investigations of the ultrastructural features of neurons and their synapses are only possible with electron microscopy. Especially for comparative studies of the changes in densities and distributions of such features, an unbiased sampling protocol is vital for reliable results. Here, we present a workflow for the image acquisition of brain samples. The workflow allows systematic uniform random sampling within a defined brain region, and the images can be analyzed using a disector. This technique is much faster than extensive examination of serial sections but still presents a feasible approach to estimate the densities and distributions of ultrastructure features. Before embedding, stained vibratome sections were used as a reference to identify the brain region under investigation, which helped speed up the overall specimen preparation process. This approach was used for comparative studies investigating the effect of an enriched-housing environment on several ultrastructural parameters in the mouse brain. Based on the successful use of the workflow, we adapted it for the purpose of elemental analysis of brain samples. We optimized the protocol in terms of the time of user-interaction. Automating all the time-consuming steps by compiling a script for the open source software SerialEM helps the user to focus on the main work of acquiring the elemental maps. As in the original workflow, we paid attention to the unbiased sampling approach to guarantee reliable results.

We introduce a novel workflow for electron microscopy investigations of brain tissue. The method allows the user to examine neuronal features in an unbiased fashion. For elemental analysis, we also present a script that automatizes most of the workflow for randomized sampling.

Investigations of the ultrastructural features of neurons and their synapses are only possible with electron microscopy. Especially for comparative ...

Light-Induced Molecular Adsorption of Proteins Using the PRIMO System for Micro-Patterning to Study Cell Responses to Extracellular Matrix Proteins

Cells sense a variety of extracellular cues, including the composition and geometry of the extracellular matrix, which is synthesized and remodeled by the cells themselves. Here, we present the method of Light-Induced Molecular Adsorption of Proteins (LIMAP) using the PRIMO system as a patterning technique to produce micro-patterned extracellular matrix (ECM) substrates using a single or combination of proteins. The method enables printing of ECM patterns in micron resolution with excellent reproducibility. We provide a step-by-step protocol and demonstrate how this can be applied to study the processes of neuronal pathfinding. LIMAP has significant advantages over existing micro-printing methods in terms of the ease of patterning more than one component and the ability to generate a pattern with any geometry or gradient. The protocol can easily be adapted to study the contribution of almost any chemical component towards cell fate and cell behavior. Finally, we discuss common issues that can arise and how these can be avoided.

Our overall aim is to understand how cells sense extracellular cues that lead to directed axonal growth. Here, we describe the methodology of Light-Induced Molecular Adsorption of Proteins, used to produce defined micro-patterns of extracellular matrix components in order to study specific events that govern axon outgrowth and pathfinding.

Cells sense a variety of extracellular cues, including the composition and geometry of the extracellular matrix, which is synthesized and remodeled by the ...