We would like to thank William A. Eimer for imaging technical assistance. This work was supported by the Cure Alzheimer's Fund [to R.E.T], the National Institute of Health [R01AG014713 and R01MH60009 to R.E.T; R03AR063271 and R15EB019704 to A.L.], and the National Science Foundation [NSF1455613 to A.L.].

1. Experimental Preparation
<ol>
	<li>Prepare the following reagents: Dulbecco&#39;s phosphate buffered saline (PBS); Triton X-100; 0.2% PBST (PBS + 0.2% Triton X-100); 32% paraformaldehyde (PFA), diluted into 4% before use; silicone elastomer base and curing agent; antifade mounting medium (e.g., ProLong Gold); and fingernail polish.</li>
	<li>Prepare the following equipment: dissection microscope, two sharp forceps and a pair of scissors for microdissection, a number of pins for microdissection, a Petri dish for making the dissection dish, microscope slides and coverslips, a confocal microscope, and a computer with Fiji ImageJ software installed.</li>
</ol>
2. Larvae Collection
<ol>
	<li>Mate UAS-Sox102F-RNAi flies with UAS-GFP, ppk-GAL4, or W1118 wild type flies, respectively. Culture flies in standard conditions at 25 &#176;C.</li>
	<li>In ~5 - 6 days, collect the third instar larvae of UAS-Sox102F-RNAi/ ppk-GAL4, UAS-GFP or UAS-GFP, and ppk-GAL4 /+ control carefully with forceps for dissection.</li>
</ol>
3. Dissection of Larvae
NOTE: All procedures in this section are operated under a microdissection microscope. The magnification is up to the investigators. Try to adjust to the optimal sight view. ~4 - 6X magnification is recommended.
<ol>
	<li>Place a larva on a dissection dish made of silicone elastomer base and a tissue culture Petri dish.</li>
	<li>Pin the larva mouth hook to allow the dorsal side to face up, and then pin the tail of larva. Place the dorsal side in the middle as much as possible to expose the midline, which will be the open-up marker.</li>
	<li>Add 200 &#181;L of PBS to the larva to maintain body moisture.</li>
	<li>Make a cut with a pair of scissors along the dorsal midline between the two tracheas, from caudal to rostral. Make a small cut at each of the four corners of the larva body.</li>
	<li>Place a pin at each of the four corners of the body so the body lies flat.</li>
	<li>Fix the larva body wall in 4% PFA for 25 min at room temperature.</li>
	<li>Wash in PBST for 5 min. Repeat twice more.</li>
	<li>Remove the pins from the tissue. Then transfer the tissue onto a glass slide, cover with antifade mounting medium, and mount with a cover slip. Air dry for 1 h and seal the edges with fingernail polish.</li>
</ol>
4. Imaging Processing
NOTE: Images were taken using an inverted confocal microscope system. The user can photograph the sample using a 20X objective (recommended).
<ol>
	<li>Capture Z-series images. Open the &#34;Capture Z-series&#34; dialog box in the confocal microscope software. Determine the range for capturing the Z series images.
	<ol>
		<li>Click the &#34;Top and Bottom&#34; button. Determine the top and bottom position and input the values to &#34;Bottom:&#34; and &#34;Top:&#34; boxes. Set the &#34;Step&#34; in &#34;Capture Z-series&#34; dialog box as 0.5 &#181;m. Then click the &#34;Run now&#34; button to acquire the Z-series images.</li>
	</ol>
	</li>
	<li>Save the obtained images as *.tiff or *.nd2 files.</li>
	<li>Store the slides in a dark holder at 4 &#176;C after imaging.</li>
</ol>
5. Dendrite Evaluation
Note: GFP protein was co-overexpressed in UAS-GFP and ppk-GAL4 flies in the da neurons for GFP fluorescence imaging analysis. The length, branching, and structure of da neurons in the third instar larvae were quantified. Analysis parameters include length of dendrites (&#181;m), surface area (&#181;m2), total number of branches, and branching structure (%). Figure 1 shows the analysis parameters in detail.
<ol>
	<li>Length of Dendrites 
	NOTE: The length of dendrites is the sum of all dendrites labeled in tracer plugin.
	<ol>
		<li>Setup and run Fiji ImageJ (https://fiji.sc/)20&#160;software. Then split images into separate channels, if there are several channels of images. 
		&#8203;NOTE: The image in this protocol only has one channel of GFP.</li>
		<li>Run &#34;Image | Stacks | Z project&#34; to get a Z projection; a new window will appear with the name &#39;Z-projection.&#39;&#160;Click &#34;max intensity&#34; for projection type, and organize numbers between start slice and stop slice depending upon individual preferences. Click &#34;OK.&#34;&#160;A Z-projection image will appear presenting the dendrite projection clearly.</li>
		<li>Trace the neurites.
		<ol>
			<li>Select &#34;Plugins | Segmentation | Simple Neurites Tracer&#34; in the window to trace the dendrites. Find the neuron soma, and then click one point at a dendrite starting from the cell body, and another point at the tip of this dendrite. 
			NOTE: The program will connect the two points with a blue line.</li>
			<li>Press &#34;Y&#34; in the plug-in window if the path is clear; the dendrite path is traced until the endpoints of the selected path in the visible images. Click &#34;complete path&#34; on the same plugin window; the segment is completed (Figure 2). 
			NOTE: Some dendrites ended farther from the starting points, in which the pathway was divided into smaller segments. The segments were combined to provide a complete path for the tracer.</li>
		</ol>
		</li>
		<li>After a path is completed, go back to a new point where the branches are. The new path can be built on; the &#34;All paths&#34; window box will show the length values of all the paths (Figure 3). Save the tracing file, and continue with unfinished traces as shown in Figure 2.</li>
		<li>Export the dendrite length data by clicking, &#34;File | Export as *.cvs&#34; in the &#39;Plugin&#39; window. Then sum up all the path lengths, and export the data to a data analysis/spreadsheet software. (Figure 3).</li>
	</ol>
	</li>
	<li>Surface Area of the da Neurons
	<ol>
		<li>Select the Freehand drawing tool in the &#39;Fiji ImageJ&#39; window. Trace the path, and then connect the endpoints. From the &#39;Analyze&#39; menu, select &#34;Set Measurements | Area.&#34;&#160;Click &#34;measure&#34; from the &#39;Analyze&#39; menu. The result appears in a new box with the value for the area selected (Figure 4). Copy it to the data analysis software.</li>
	</ol>
	</li>
	<li>Total Number of Branches and Branching Structure of the da Neurons
	<ol>
		<li>Calculate the total number of branches by opening &#34;Analysis&#34; and then &#34;Render | Analyze Skeletonized Paths&#34; in the plugin window of tracing (Figure 5). 
		NOTE: The structure of the arbor is the sum of the levels of branches. The path was defined between the cell body and the dendrite tips, and one path can include multiple branches, such as the primary arbors are the dendrites from the neuron cell body. The secondary arbors are branches from the primary and so on with the tertiary, quaternary, and quinary arbors. The structure of dendrite branching is separated depending on the levels of branches. For instance, the primary % is the number of branches divided by total number of branching, and so on.</li>
	</ol>
	</li>
</ol>

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The authors have nothing to disclose.

Dendrites that innervate the epidermis are the input regions of neurons, and their morphologies determine how information is received and processed by individual neurons. Development dendrite morphology reflects gene modulation of dendrite organization. The Drosophila larval da neuron of the peripheral nervous system is an important model for studying dendrite development because of: 1) the functional similarity with mammals11,12; 2) four class distincti...

Dendrites, which are the branched projections of a neuron, cover the field that encompasses the neuron&#39;s sensory and synaptic inputs from other neurons1,2. Dendrites are an important component of synapse formation and play a critical role in integrating synaptic inputs, as well as propagating the electrochemical stimulation in a neuron. Dendritic arborization (da) is a process by which neurons form new dendritic trees and branches to create new synapses. The development and morphology of da, such as branch density and grouping patterns, result from multi-step biological processes and are highly correlated to neuronal function. The goal of this protocol is to provide a method for quantitative analysis of neuronal dendritric arborization complexity in Drosophila. 
The complexity of dendrites determines the synaptic types, connectivity, and inputs from partner neurons. Branching patterns and the density of dendrites are involved in processing the signals that converge onto the dendritic field3,4. Dendrites have the flexibility for adjustment in development. For instance, synaptic signaling has an effect on dendrite organization in the somatosensory neuron during the developmental phase and in the mature nervous system5. The establishment of neuronal connectivity relies on the morphogenesis and maturation of dendrites. Malformation of dendrites is associated with impaired neuronal function. Studies have shown that the abnormality of da neuron morphogenesis might contribute to the etiologies of multiple neurodegenerative diseases, including Alzheimer&#39;s disease (AD), Parkinson&#39;s disease (PD), Huntington&#39;s disease (HD), and Lou Gehrig&#39;s disease/Amyotrophic lateral sclerosis (ALS)6,7,8. Synaptic alterations appear in the early stage of AD, in concert with the decline and impairment of neuron function7,8. However, the specifics of how dendrite pathology contributes to pathogenesis in these neurodegenerative diseases remains elusive.
The development of dendrites is regulated by genes that encode a complex network of regulators, such as the Wnt family of proteins9,10, transcription factors, and ligands on cell surface receptors11,12. Drosophila da neurons consist of four classes (Class I, II III, IV), of which class IV da neurons have the most complex branching patterns and have been employed as a powerful experimental system for better understanding morphogenesis13,14. During early morphogenesis, overexpression and/or RNAi silencing of genes in class IV da neurons result in changes in branching patterns and dendrite pruning13. It is important to develop a practical method for quantitative analysis of the neuronal dendritic arborization.
We have previously shown that silencing of the Drosophila ortholog of SOX5, Sox102F, led to shorter dendrites of da neurons and reduced complexity in class IV da neurons15. Here, we present the procedure of quantitative analysis for the neuronal dendritic arborization complexity (NDAC) in Drosophila. This protocol, adapted from the previous described methodology, provides a brief method to assay the development of da sensory neurons. It illustrates the robust image labeling and the da neuron in the third instar larval body wall16,17,18,19. It is a valuable protocol for researchers who wish to investigate the NDAC and developmental differences in vivo.

<table><tbody><tr><td>Phosphate buffered saline(PBS)</td><td>Gibco Life Sciences</td><td>10010-023</td><td></td></tr><tr><td>TritonX-100</td><td>Fisher Scientific</td><td>9002-93-1</td><td></td></tr><tr><td>Paraformaldehyde(PFA)</td><td>Electron Microscopy Sciences</td><td>15714-S</td><td></td></tr><tr><td>Sylgard 184 silicone elastomer base and curing agent</td><td>Dow Corning Corportation</td><td>3097366-0516;3097358-1004</td><td></td></tr><tr><td>ProLong Gold Antifade Mountant</td><td>Thermo Fisher Scientific</td><td>P36931</td><td></td></tr><tr><td>Fingernail polish&amp;nbsp;</td><td>CVS</td><td>72180</td><td></td></tr><tr><td>Stereo microscope</td><td>Nikon</td><td>SMZ800</td><td></td></tr><tr><td>Confocal microscope</td><td>Nikon</td><td>Eclipse Ti-E</td><td></td></tr><tr><td>Petri dish</td><td>Falcon</td><td>353001</td><td></td></tr><tr><td>Forceps</td><td>Dumont</td><td>11255-20</td><td></td></tr><tr><td>Scissors&amp;nbsp;</td><td>Roboz Surgical Instrument Co</td><td>RS-5611</td><td></td></tr><tr><td>Insect Pins&amp;nbsp;</td><td>Roboz Surgical Instrument Co</td><td>RS-6082-25</td><td></td></tr><tr><td>Microscope slides and cover slips</td><td>Fisher Scientific</td><td>15-188-52</td><td></td></tr></tbody></table>

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.

The dendrites of da neurons were labeled by co-overexpressing GFP (UAS-GFP; ppk-GAL4) in the da neural soma and dendritic arbors for GFP fluorescence imaging analysis. The morphology of da neuron dendrites was imaged by an inverted confocal microscope (Figure 2).
The dendrites of da neurons were traced using Fiji ImageJ software. The file was used to estimate the dendrite length (<strong class="xfig...

Watch this Scientific Journal Video about Quantitative Analysis of Neuronal Dendritic Arborization Complexity in Drosophila at JoVE.com

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.

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. ...

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14.0K Views.  Mass General Institute of Neurodegenerative Disease. Het algemene doel van deze procedure is om de impact van het SOX5-gen op de complexiteit van de dendritische arborisatieneuronen tijdens de neuronale ontwikkeling in Drosophila te observeren. Deze methode kan helpen bij het bestuderen van morfogenese van neuro-dendrieten, en de genfunctie in de ontwikkeling van het zenuwstelsel, om neurodegeneratieve ziektegenen beter te begrijpen. Uiteindelijk biedt deze techniek een kwantitatieve analyse van de complexiteit van dendrieten, die kan worden ge...

Video: Quantitative Analysis of Neuronal Dendritic Arborization Complexity in Drosophila

Morphological Analysis of Drosophila Larval Peripheral Sensory Neuron Dendrites and Axons Using Genetic Mosaics

Nervous system development requires the correct specification of neuron position and identity, followed by accurate neuron class-specific dendritic development and axonal wiring. Recently the dendritic arborization (DA) sensory neurons of the Drosophila larval peripheral nervous system (PNS) have become powerful genetic models in which to elucidate both general and class-specific mechanisms of neuron differentiation.
There are four main DA neuron classes (I-IV)1. They are named in order of increasing dendrite arbor complexity, and have class-specific differences in the genetic control of their differentiation2-10. The DA sensory system is a practical model to investigate the molecular mechanisms behind the control of dendritic morphology11-13 because: 1) it can take advantage of the powerful genetic tools available in the fruit fly, 2) the DA neuron dendrite arbor spreads out in only 2 dimensions beneath an optically clear larval cuticle making it easy to visualize with high resolution in vivo, 3) the class-specific diversity in dendritic morphology facilitates a comparative analysis to find key elements controlling the formation of simple vs. highly branched dendritic trees, and 4) dendritic arbor stereotypical shapes of different DA neurons facilitate morphometric statistical analyses.
DA neuron activity modifies the output of a larval locomotion central pattern generator14-16. The different DA neuron classes have distinct sensory modalities, and their activation elicits different behavioral responses14,16-20. Furthermore different classes send axonal projections stereotypically into the Drosophila larval central nervous system in the ventral nerve cord (VNC)21. These projections terminate with topographic representations of both DA neuron sensory modality and the position in the body wall of the dendritic field7,22,23. Hence examination of DA axonal projections can be used to elucidate mechanisms underlying topographic mapping7,22,23, as well as the wiring of a simple circuit modulating larval locomotion14-17.
We present here a practical guide to generate and analyze genetic mosaics24 marking DA neurons via MARCM (Mosaic Analysis with a Repressible Cell Marker)1,10,25 and Flp-out22,26,27 techniques (summarized in Fig. 1).

Morphological Analysis of Drosophila Larval Peripheral Sensory Neuron Dendrites and Axons Using Genetic Mosaics

The dendritic arborization sensory neurons of the Drosophila larval peripheral nervous system are useful models to elucidate both general and neuron class-specific mechanisms of neuron differentiation. We present a practical guide to generate and analyze dendritic arborization neuron genetic mosaics.

Nervous system development requires the correct specification of neuron position and identity, followed by accurate neuron class-specific dendritic ...

Immunohistological Labeling of Microtubules in Sensory Neuron Dendrites, Tracheae, and Muscles in the Drosophila Larva Body Wall

To understand how differences in complex cell shapes are achieved, it is important to accurately follow microtubule organization. The Drosophila larval body wall contains several cell types that are models to study cell and tissue morphogenesis. For example tracheae are used to examine tube morphogenesis1, and the dendritic arborization (DA) sensory neurons of the Drosophila larva have become a primary system for the elucidation of general and neuron-class-specific mechanisms of dendritic differentiation2-5 and degeneration6.
The shape of dendrite branches can vary significantly between neuron classes, and even among different branches of a single neuron7,8. Genetic studies in DA neurons suggest that differential cytoskeletal organization can underlie morphological differences in dendritic branch shape4,9-11. We provide a robust immunological labeling method to assay in vivo microtubule organization in DA sensory neuron dendrite arbor (Figures 1, 2, Movie 1). This protocol illustrates the dissection and immunostaining of first instar larva, a stage when active sensory neuron dendrite outgrowth and branching organization is occurring 12,13.
In addition to staining sensory neurons, this method achieves robust labeling of microtubule organization in muscles (Movies 2, 3), trachea (Figure 3, Movie 3), and other body wall tissues. It is valuable for investigators wishing to analyze microtubule organization in situ in the body wall when investigating mechanisms that control tissue and cell shape.

Immunohistological Labeling of Microtubules in Sensory Neuron Dendrites, Tracheae, and Muscles in the Drosophila Larva Body Wall

To understand how complex cell shapes, such as neuronal dendrites, are achieved during development, it is important to be able to accurately assay microtubule organization. Here we describe a robust immunohistological labeling method to examine microtubule organization of dendritic arborization neuron sensory dendrites, trachea, muscle, and other Drosophila larva body wall tissues.

To understand how differences in complex cell shapes are achieved, it is important to accurately follow microtubule organization. The Drosophila larval ...

Assessment of Dendritic Arborization in the Dentate Gyrus of the Hippocampal Region in Mice

Dendritic arborization has been shown to be a reliable marker for examination of structural and functional integrity of neurons. Indeed, the complexity and extent of dendritic arborization correlates well with the synaptic plasticity in these cells. A reliable method for assessment of dendritic arborization is needed to characterize the deleterious effects of neurological disorders on these structures and to determine the effects of therapeutic interventions. However, quantification of these structures has proven to be a formidable task given their complex and dynamic nature. Fortunately, sophisticated imaging techniques can be paired with conventional staining methods to assess the state of dendritic arborization, providing a more reliable and expeditious means of assessment. Below is an example of how these imaging techniques were paired with staining methods to characterize the dendritic arborization in wild type mice. These complementary imaging methods can be used to qualitatively and quantitatively assess dendritic arborization that span a rather wide area within the hippocampal region.

We describe two methods for visualization and quantification of dendritic arborization in the hippocampus of mouse models: real-time and extended depth of field imaging. While the former method allows sophisticated topographical tracing and quantification of the extent of branching, the latter allows speedy visualization of the dendritic tree.

Dendritic arborization has been shown to be a reliable marker for examination of structural and functional integrity of neurons. Indeed, the complexity ...

Removal of Drosophila Muscle Tissue from Larval Fillets for Immunofluorescence Analysis of Sensory Neurons and Epidermal Cells

Drosophila larval dendritic arborization (da) neurons are a popular model for investigating mechanisms of neuronal morphogenesis. Da neurons develop in communication with the epidermal cells they innervate and thus their analysis benefits from in situ visualization of both neuronally and epidermally expressed proteins by immunofluorescence. Traditional methods of preparing larval fillets for immunofluorescence experiments leave intact the muscle tissue that covers most of the body wall, presenting several challenges to imaging neuronal and epidermal proteins. Here we describe a method for removing muscle tissue from Drosophila larval fillets. This protocol enables imaging of proteins that are otherwise obscured by muscle tissue, improves signal to noise ratio, and facilitates the use of super-resolution microscopy to study da neuron development.

Removal of Drosophila Muscle Tissue from Larval Fillets for Immunofluorescence Analysis of Sensory Neurons and Epidermal Cells

Studies of neuronal morphogenesis using Drosophila larval dendritic arborization (da) neurons benefit from in situ visualization of neuronal and epidermal proteins by immunofluorescence. We describe a procedure that improves immunofluorescence analysis of da neurons and surrounding epidermal cells by removing muscle tissue from the larval body wall.

Drosophila larval dendritic arborization (da) neurons are a popular model for investigating mechanisms of neuronal morphogenesis. Da neurons develop in ...

Analyzing Synaptic Modulation of Drosophila melanogaster Photoreceptors after Exposure to Prolonged Light

The nervous system has the remarkable ability to adapt and respond to various stimuli. This neural adjustment is largely achieved through plasticity at the synaptic level. The Active Zone (AZ) is the region at the presynaptic membrane that mediates neurotransmitter release and is composed of a dense collection of scaffold proteins. AZs of Drosophila melanogaster (Drosophila) photoreceptors undergo molecular remodeling after prolonged exposure to natural ambient light. Thus the level of neuronal activity can rearrange the molecular composition of the AZ and contribute to the regulation of the functional output.
Starting from the light exposure set-up preparation to the immunohistochemistry, this protocol details how to quantify the number, the spatial distribution, and the delocalization level of synaptic molecules at AZs in Drosophila photoreceptors. Using image analysis software, clusters of the GFP-fused AZ component Bruchpilot were identified for each R8 photoreceptor (R8) axon terminal. Detected Bruchpilot spots were automatically assigned to individual R8 axons. To calculate the distribution of spot frequency along the axon, we implemented a customized software plugin. Each axon&#39;s start-point and end-point were manually defined and the position of each Bruchpilot spot was projected onto the connecting line between start and end-point. Besides the number of Bruchpilot clusters, we also quantified the delocalization level of Bruchpilot-GFP within the clusters. These measurements reflect in detail the spatially resolved synaptic dynamics in a single neuron under different environmental conditions to stimuli.

Analyzing Synaptic Modulation of Drosophila melanogaster Photoreceptors after Exposure to Prolonged Light

Here we show how to quantify the number and spatial distribution of synaptic active zones in Drosophila melanogaster&#160;photoreceptors, highlighted with a genetically encoded molecular marker, and their modulation after prolonged exposure to light.

The nervous system has the remarkable ability to adapt and respond to various stimuli. This neural adjustment is largely achieved through plasticity at ...

Two Algorithms for High-throughput and Multi-parametric Quantification of Drosophila Neuromuscular Junction Morphology

Synaptic morphology is tightly related to synaptic efficacy, and in many cases morphological synapse defects ultimately lead to synaptic malfunction. The Drosophila larval neuromuscular junction (NMJ), a well-established model for glutamatergic synapses, has been extensively studied for decades. Identification of mutations causing NMJ morphological defects revealed a repertoire of genes that regulate synapse development and function. Many of these were identified in large-scale studies that focused on qualitative approaches to detect morphological abnormalities of the Drosophila NMJ. A drawback of qualitative analyses is that many subtle players contributing to NMJ morphology likely remain unnoticed. Whereas quantitative analyses are required to detect the subtler morphological differences, such analyses are not yet commonly performed because they are laborious. This protocol describes in detail two image analysis algorithms "Drosophila NMJ Morphometrics" and "Drosophila NMJ Bouton Morphometrics", available as Fiji-compatible macros, for quantitative, accurate and objective morphometric analysis of the Drosophila NMJ. This methodology is developed to analyze NMJ terminals immunolabeled with the commonly used markers Dlg-1 and Brp. Additionally, its wider application to other markers such as Hrp, Csp and Syt is presented in this protocol. The macros are able to assess nine morphological NMJ features: NMJ area, NMJ perimeter, number of boutons, NMJ length, NMJ longest branch length, number of islands, number of branches, number of branching points and number of active zones in the NMJ terminal.

Two Algorithms for High-throughput and Multi-parametric Quantification of Drosophila Neuromuscular Junction Morphology

Two image analysis algorithms, "Drosophila NMJ Morphometrics" and "Drosophila NMJ Bouton Morphometrics" were created, to automatically quantify nine morphological features of the Drosophila neuromuscular junction (NMJ).

Synaptic morphology is tightly related to synaptic efficacy, and in many cases morphological synapse defects ultimately lead to synaptic malfunction. The ...

Analyzing Dendritic Morphology in Columns and Layers

In many regions of the central nervous systems, such as the fly optic lobes and the vertebrate cortex, synaptic circuits are organized in layers and columns to facilitate brain wiring during development and information processing in developed animals. Postsynaptic neurons elaborate dendrites in type-specific patterns in specific layers to synapse with appropriate presynaptic terminals. The fly medulla neuropil is composed of 10 layers and about 750 columns; each column is innervated by dendrites of over 38 types of medulla neurons, which match with the axonal terminals of some 7 types of afferents in a type-specific fashion. This report details the procedures to image and analyze dendrites of medulla neurons. The workflow includes three sections: (i) the dual-view imaging section combines two confocal image stacks collected at orthogonal orientations into a high-resolution 3D image of dendrites; (ii) the dendrite tracing and registration section traces dendritic arbors in 3D and registers dendritic traces to the reference column array; (iii) the dendritic analysis section analyzes dendritic patterns with respect to columns and layers, including layer-specific termination and planar projection direction of dendritic arbors, and derives estimates of dendritic branching and termination frequencies. The protocols utilize custom plugins built on the open-source MIPAV (Medical Imaging Processing, Analysis, and Visualization) platform and custom toolboxes in the matrix laboratory language. Together, these protocols provide a complete workflow to analyze the dendritic routing of Drosophila medulla neurons in layers and columns, to identify cell types, and to determine defects in mutants.

Here, we show how to analyze dendritic routing of Drosophila medulla neurons in columns and layers. The workflow includes a dual-view imaging technique to improve the image quality and computational tools for tracing, registering dendritic arbors to the reference column array and for analyzing the dendritic structures in 3D space.

In many regions of the central nervous systems, such as the fly optic lobes and the vertebrate cortex, synaptic circuits are organized in layers and ...

Assessment of Hippocampal Dendritic Complexity in Aged Mice Using the Golgi-Cox Method

Dendritic spines are the protuberances from the neuronal dendritic shafts that contain&#160; excitatory synapses. The morphological and branching variations of the neuronal dendrites within the hippocampus are implicated in cognition and memory formation. There are several approaches to Golgi staining, all of which have been useful for determining the morphological characteristics of dendritic arbors and produce a clear background. The present Golgi-Cox method, (a slight variation of the protocol that is provided with a commercial Golgi staining kit), was designed to assess how a relatively low dose of the chemotherapeutic drug 5-flurouracil (5-Fu) would affect dendritic morphology, the number of spines, and the complexity of arborization within the hippocampus. The 5-Fu significantly modulated the dendritic complexity and decreased the spine density throughout the hippocampus in a region-specific manner. The data presented show that the Golgi staining method effectively stained the mature neurons in the CA1, the CA3, and the dentate gyrus (DG) of the hippocampus. This protocol reports the details for each step so that other researchers can reliably stain tissue throughout the brain with high quality results and minimal troubleshooting.

Here we present a Golgi-Cox protocol in extensive detail. This reliable tissue stain method allows for a high-quality assessment of the cytoarchitecture in the hippocampus, and throughout the entire brain, with minimal troubleshooting.

Dendritic spines are the protuberances from the neuronal dendritic shafts that contain&#160; excitatory synapses. The morphological and branching ...

Visualization of Motor Axon Navigation and Quantification of Axon Arborization In Mouse Embryos Using Light Sheet Fluorescence Microscopy

Spinal motor neurons (MNs) extend their axons to communicate with their innervating targets, thereby controlling movement and complex tasks in vertebrates. Thus, it is critical to uncover the molecular mechanisms of how motor axons navigate to, arborize, and innervate their peripheral muscle targets during development and degeneration. Although transgenic Hb9::GFP mouse lines have long served to visualize motor axon trajectories during embryonic development, detailed descriptions of the full spectrum of axon terminal arborization remain incomplete due to the pattern complexity and limitations of current optical microscopy. Here, we describe an improved protocol that combines light sheet fluorescence microscopy (LSFM) and robust image analysis to qualitatively and quantitatively visualize developing motor axons. This system can be easily adopted to cross genetic mutants or MN disease models with Hb9::GFP lines, revealing novel molecular mechanisms that lead to defects in motor axon navigation and arborization.

Here, we describe a protocol for visualizing motor neuron projection and axon arborization in transgenic Hb9::GFP mouse embryos. After immunostaining for motor neurons, we used light sheet fluorescence microscopy to image embryos for subsequent quantitative analysis. This protocol is applicable to other neuron navigation processes in the central nervous system.

Spinal motor neurons (MNs) extend their axons to communicate with their innervating targets, thereby controlling movement and complex tasks in ...

Time-lapse Live Imaging and Quantification of Fast Dendritic Branch Dynamics in Developing Drosophila Neurons

Highly motile dendritic filopodia are widely present in neurons at early developmental stages. These exploratory dynamic branches sample the surrounding environment and initiate contacts with potential synaptic partners. Although the connection between dendritic branch dynamics and synaptogenesis is well established, how developmental and activity-dependent processes regulate dendritic branch dynamics is not well understood. This is partly due to the technical difficulties associated with the live imaging and quantitative analyses of these fine structures using an in vivo system. We established a method to study dendrite dynamics using Drosophila larval ventral lateral neurons (LNvs), which can be individually labeled using genetic approaches and are accessible for live imaging. Taking advantage of this system, we developed protocols to capture branch dynamics of the whole dendritic arbor of a single labeled LNv through time-lapse live imaging. We then performed post-processing to improve image quality through drift correction and deconvolution, followed by analyzing branch dynamics at the single-branch level by annotating spatial positions of all branch terminals. Lastly, we developed R scripts (Supplementary File) and specific parameters to quantify branch dynamics using the coordinate information generated by the terminal tracing. Collectively, this protocol allows us to achieve a detailed quantitative description of branch dynamics of the neuronal dendritic arbor with high temporal and spatial resolution. The methods we developed are generally applicable to sparsely labeled neurons in both in vitro and in vivo conditions.

Time-lapse Live Imaging and Quantification of Fast Dendritic Branch Dynamics in Developing Drosophila Neurons

Here, we describe the method we employed to image highly motile dendritic filopodia in a live preparation of the Drosophila larval brain, and the protocol we developed to quantify time-lapse 3D imaging datasets for quantitative assessments of dendrite dynamics in developing neurons.

Highly motile dendritic filopodia are widely present in neurons at early developmental stages. These exploratory dynamic branches sample the surrounding ...

Quantitative Analysis of Neuronal Dendritic Arborization Complexity in Drosophila

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