Name: immunofluorescence staining of drosophila brains for the single-cell imaging of glial cells
Uploaded: 2025-03-31T15:00:41.000+00:00
Duration: 1 min 20 s
Description: Source: Batelli, S., et al. Application of MultiColor FlpOut Technique to Study High Resolution Single Cell Morphologies and Cell Interactions of Glia in ...

immunofluorescence staining of drosophila brains for the single-cell imaging of glial cells

Immunofluorescence Staining of Drosophila Brains for the Single-Cell Imaging of Glial Cells

Transfer the isolated brains using a P10 pipette tip into a 200-microliter microcentrifuge tube with fixative solution. Never handle the brains using forceps. Incubate the tissues protected from light. Avoid aspirating the brains during solution transfers.
To remove the fixative, use three or more 15-minute washes with washing solution. Then, block the tissues with blocking solution for 30 minutes or longer. Next, replace the blocking solution with primary antibodies diluted in wash solution, and incubate the brains overnight at 4 degrees Celsius.
To remove the primary antibodies, use three 1-hour washes in wash solution. Next, add secondary fluorophore conjugated antibodies in wash solution, and incubate the brains overnight at 4 degrees Celsius, or for 4 hours at room temperature. To completely wash off the unbound antibodies, use three 1-hour washes in wash solution, followed by a longer wash with PBS.
Then, mount the brains. Prepare two coverslips with an imaging spacer. In the spacer, and on the extra coverslip, apply 10 microliters of mounting medium with an anti-fade agent. Next, using a P10 pipette, transfer the brains to the coverslip, depositing them next to the medium along with some PBS. Do not let the tissue dry out.
Now, carefully move the brains into the mounting medium, using the pipette. And finally, move them to the medium in the spacer and arrange them with forceps. Then, remove the adhesive liner on the spacers and attach a coverslip. Secure the coverslip with a little pressure using forceps and proceed immediately with imaging.

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1. Preparing Flies for MultiColor FlpOut (MCFO) Experiments
NOTE: The MCFO technique refers to a modified version of the so called Flp-mediated stop cassette excision (FlpOut). Transgenic MCFO flies carry a heat shock promoter (hsp)-Flp recombinase and different reporters under upstream activation sequence (UAS) control. Each reporter consists of a common backbone of a myristoylated (myr) super folder green fluorescent protein (sfGFP), in which 10 copies of an epitope tag (e.g., HA, FLAG or V5) have been inserted. The resulting non-fluorescent proteins are named &#34;spaghetti monster GFPs&#34; (smGFPs)&#160;and can be detected using specific antibodies against the different epitope tags.
<ol>
	<li>Cross flies with the MCFO cassette and the hsp-Flp (hsp-Flp; 10XUAS-FRT-stop-FRT-myr-smGFP-HA,10XUAS-FRT-stop-FRT-myr-smGFP-FLAG, 10XUAS-FRT-stop-FRT-myr-smGFP-V5) to the appropriate glial GAL4 driver lines (see Table of Materials).
	<ol>
		<li>As the hsp is already active at 25 &#176;C and few cells may undergo recombination leading to an unspecific labeling, set up crosses at 18 &#176;C in order to avoid leakiness of the system. Wait around 20 days at 18 &#176;C to obtain the F1 generation. After the heat shock (see step 2), maintain flies at 25 &#176;C (Figure 1).</li>
	</ol>
	</li>
</ol>
2. Heat Shock
NOTE: Depending on the insertion site, the efficiency of the hsp-Flp may differ; therefore, the optimal heat shock time has to be optimized. For this protocol, a MCFO fly stock in which the hsp-Flp was inserted on the X chromosome has been used (see&#160;Table of Materials).
<ol>
	<li>Transfer the progeny of the cross in step 1.1 (F1 generation flies, 3-4 days old) into new vials containing food and heat shock them at 37 &#176;C in a water bath. 
	NOTE: Young flies (1-2 days old) are very sensitive to heat shock. Wait 1 or 2 more days before performing the heat shock in order to reduce the mortality rate caused by the treatment. Use some of the F1 generation flies as a control, without heat shock.</li>
	<li>During the heat shock, maintain flies in normal vials with food in order to decrease the rate of stress-induced mortality. Put females and males in separate vials.</li>
	<li>Make sure to immerse the entire vial in the water to ensure a homogeneous heat shock. Use a 5-8 min shock as a suitable starting point for sparse labeling of glia cells with many GAL4 driver lines; the shock duration must be optimized for each driver and experiment (shorter or longer heat shock times may be necessary).</li>
	<li>After the heat shock, lay the vials horizontally on the bench for a few minutes in order to allow the flies to recover from the heat shock. 
	NOTE: It is not necessary to change the vials.</li>
	<li>Maintain the flies at 25 &#176;C and dissect (see step 3 and 4) them 2 or more days after the heat shock for optimal reporter expression.</li>
</ol>
3. Dissection Preparation and Solutions
<ol>
	<li>The day of the dissection, prepare fresh fixative solution in 200 &#181;L PCR tubes by mixing 180 &#181;L of S2 cell culture medium with 20 &#181;L of 20% paraformaldehyde (PFA) to obtain a 2% PFA solution. Maintain the fixative solution on ice before and during the dissection. 
	Caution: PFA is toxic and must be handled with care. 
	NOTE: Mix 160 &#181;L of S2 cell culture medium with 40 &#181;L of 20% paraformaldehyde (PFA) in a 200 &#181;L polymerase chain reaction (PCR) tube to prepare a 4% PFA solution instead of a 2% solution.</li>
	<li>Use one PCR tube per genotype with a maximum of 8-10 brains per tube for optimal staining results.</li>
	<li>Prepare the adult brain washing solution: 0.5% bovine serum albumin, 0.5% Triton X-100 in phosphate-buffered saline (PBS). 
	NOTE: Depending on the staining, a solution containing 1% Triton X-100 may be needed. A higher concentration of Triton X-100 increases the penetration of the antibody into the tissue and it is necessary to stain regions that lie deep inside the tissue (e.g.,&#160;synaptic regions in the adult&#160;Drosophila&#160;brain).</li>
	<li>Prepare the blocking solution: 3% normal goat serum, 3% normal donkey serum, and 0.5% Triton X-100 in PBS.</li>
	<li>The adult brain washing solution and the blocking solution can be stored at 4 &#176;C for a few weeks.</li>
	<li>Put deep depression wells glass plate on ice and fill each well with the following solutions: one with 70% ethanol, one with PBS, and one with S2 cell culture medium.</li>
</ol>
4. Adult Brain Dissection
<ol>
	<li>Position a 3 cm dissecting dish on the stage of a stereomicroscope and fill it with cold S2 cell culture medium. Conduct all the dissections in this medium to ensure that the tissue remains healthy during the dissection procedure. 
	NOTE: Use a dissecting dish lined with several millimeters of black silicone which provides a good background contrast (in the images), and preserve the forceps during the dissection.</li>
	<li>Anesthetize the flies of the desired genotype with CO2.</li>
	<li>With forceps, grab the fly by the wings and wash it in cold 70 % ethanol for 30 s, then with cold PBS for an additional 30 s.</li>
	<li>Transfer the fly into the deep depression well that is filled with S2 cell culture medium.</li>
	<li>Repeat the same procedure for all flies of the same genotype and maintain them in cold S2 cell culture medium until dissection, which will preserve the tissue. 
	NOTE: Anesthetize only the number of flies that can be dissected in a time period of about 30 min. Long incubation times in S2 cell culture medium may damage the tissue.</li>
	<li>Grab the fly with forceps and, under a stereomicroscope, submerge the fly in S2 cell culture medium.</li>
	<li>Detach the head from the rest of the body. Discard the body and keep the head submerged in S2 cell culture medium. It is extremely important to hold the head with forceps for the entire duration of the dissection. If the head starts to float, it will be difficult to retrieve it without damaging the tissue.</li>
	<li>Begin the dissection by pulling out one eye, while holding the head with at least one forceps at all times. Make sure that the tip of the forceps is just below the retina to avoid damaging the tissue underneath. Pull out the other eye and begin removing the cuticle until the brain appears.</li>
	<li>Remove all tracheal tissue and cuticle around the brain until the tissue appears clean. Make sure to remove all tracheal tissue around the brain for optimal staining results; the tissues are now ready to be fixed and stained.</li>
	<li>Maintain all the dissected brains in cold S2 cell culture medium before transferring them into the PFA solution in order to time the fixation step.</li>
</ol>
5. Adult Brain Staining
<ol>
	<li>Transfer the isolated brain with a P10 pipette into the PFA solution at room temperature (RT). To avoid tissue damage, never use forceps for transferring the brains after the dissection. Perform all steps in 200 &#181;L PCR tubes on a nutator.</li>
	<li>For all steps, before discarding the old solution with a P200 pipette, allow the brains to settle on the bottom of the tube. Try to remove the supernatant without aspirating the tissue. Protect the tissue from light exposure.</li>
	<li>Fix the brains in 200 &#181;L of 2% PFA in S2 cell culture medium for 1 h or in 4% PFA for 30 minutes. Keep fixation times identical between samples in order to increase reproducibility.</li>
	<li>After 3 (or more) washes of 15 minutes each in 200 &#181;L of adult brain washing solution, block the tissues with 200 &#181;L of blocking solution for 30 minutes. Longer incubation times in blocking solution are possible.</li>
	<li>Incubate the brains overnight at 4 &#176;C with primary antibodies diluted in adult brain washing solution in a total volume of 200 &#181;L. 
	NOTE: The incubation times may vary depending on the type of antibody used. Longer incubations may be necessary.
	<ol>
		<li>For labeling of the three MCFO markers, incubate the brains with anti-HA (1:500), anti-FLAG (DYKDDDDK epitope) (1:100), and anti-V5 primary antibodies.</li>
		<li>Primary directly-conjugated antibodies could be used instead of the normal primary + secondary combination (e.g., anti-V5:DyLight 549 (1:200)). In this case, treat the directly-conjugated antibodies as secondary antibodies. 
		NOTE: For each genotype, keep some brains as controls to verify the specificity of the staining. Skip the primary antibody incubation and go directly to the next step.</li>
	</ol>
	</li>
	<li>Wash the tissues 3 times for 1 h in 200 &#181;L of adult brain washing solution (step 3.3) and incubate them with secondary fluorophore-conjugates/primary directly-conjugated antibodies diluted in adult brain washing solution overnight at 4 &#176;C or for 4 h at RT, in a total volume of 200 &#181;L 
	NOTE: Examples of appropriate antibodies: AlexaFluor 488 (1:250), anti-V5:DyLight 549 (1:200) and DyLight 647 (1:100)-conjugated antibodies.</li>
	<li>Wash the brains 3 times for 1 h in 200 &#181;L of adult brain washing solution, followed by a final wash in 200 &#181;L of PBS overnight at 4 &#176;C or for 1-2 h at RT; the final washing step in PBS removes any traces of Triton X-100 and is necessary for optimal staining results. Mount the brains in mounting medium with an anti-fade agent on glass coverslips.</li>
</ol>
6. Mounting of Brains for Imaging
<ol>
	<li>Trim an imaging spacer to the appropriate size using scissors. For high-resolution microscopy, sandwich the specimen and imaging spacer between two glass coverslips. 
	NOTE: Imaging spacers are thin (0.12 mm thick) adhesive spacers that peel and stick to glass coverslips or microscope slides, allowing the mounting of specimens without compression.</li>
	<li>Using forceps, remove the adhesive liner from one surface and apply the spacer, adhesive side down, on the surface of a glass coverslip (22 mm x 60 mm). Apply 10 &#181;L of mounting medium to a new glass coverslip.</li>
	<li>With a P10 pipette, transfer the brains from the 200 &#181;L tube to the coverslip, next to the drop of mounting medium. Together with the tissues, transfer some PBS in order to maintain the brains in solution.</li>
	<li>With a P10 pipette, move the brains from the PBS to the drop of mounting medium trying to limit the amount of PBS. Transfer the specimens in mounting medium on the coverslip with the imaging spacer. Use enough mounting media to cover the specimen.</li>
	<li>Remove the other adhesive liner from the upper side of the spacer and add a glass coverslip on top of the specimens. With the tip of a forceps, apply a gentle pressure over the adhesive area to seal. Image the mounted tissues immediately or store the slides at -20 &#176;C for later analysis.</li>
</ol>

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>Water bath</td>
			<td>Grant</td>
			<td>GD100</td>
			<td></td>
		</tr>
		<tr>
			<td>PCR tubes</td>
			<td>Sarstedt</td>
			<td>72.737.002</td>
			<td></td>
		</tr>
		<tr>
			<td>Forceps</td>
			<td>Dumont</td>
			<td>11251-20</td>
			<td></td>
		</tr>
		<tr>
			<td>Dissecting dish 30 mm x 12 mmm</td>
			<td>Electron Microscopy Sciences</td>
			<td>70543-30</td>
			<td>Glass dissection dish</td>
		</tr>
		<tr>
			<td>Pyrex 3 Depression Glass Spot Plate</td>
			<td>Corning</td>
			<td>7223-34</td>
			<td>Glass dissection plates</td>
		</tr>
		<tr>
			<td>Sylgard Black</td>
			<td>SYLGARD, Sigma-Aldrich</td>
			<td>805998</td>
			<td>home made with charcoal</td>
		</tr>
		<tr>
			<td>ExpressFive S2 cell culture medium</td>
			<td>Invitrogen</td>
			<td>10486-025</td>
			<td></td>
		</tr>
		<tr>
			<td>20% PFA</td>
			<td>Electron Microscopy Sciences</td>
			<td>15713</td>
			<td></td>
		</tr>
		<tr>
			<td>Triton X-100</td>
			<td>Roth</td>
			<td>3051.3</td>
			<td></td>
		</tr>
		<tr>
			<td>Normal goat serum</td>
			<td>Jackson Laboratories</td>
			<td>005-000-121</td>
			<td></td>
		</tr>
		<tr>
			<td>Normal donkey serum</td>
			<td>Jackson Laboratories</td>
			<td>017-000-121</td>
			<td></td>
		</tr>
		<tr>
			<td>Bovine Serum Albumin</td>
			<td>Sigma</td>
			<td>A9647</td>
			<td></td>
		</tr>
		<tr>
			<td>Rabbit HA-tag</td>
			<td>Cell Signaling</td>
			<td>C29F4</td>
			<td>Primary antibody, dilution 1:500</td>
		</tr>
		<tr>
			<td>Rat FLAG-tag</td>
			<td>Novus Biologicals</td>
			<td>NBP1-06712</td>
			<td>Primary antibody, dilution 1:100</td>
		</tr>
		<tr>
			<td>Mouse V5-tag:DyLight 549</td>
			<td>AdSerotec</td>
			<td>411</td>
			<td>Conjugated antibody, dilution 1:200</td>
		</tr>
		<tr>
			<td>anti-rabbit AlexaFluor 488</td>
			<td>Invitrogen</td>
			<td>A11034</td>
			<td>Secondary antibody, dilution 1:250</td>
		</tr>
		<tr>
			<td>anti-rat DyLight 647</td>
			<td>Jackson Laboratories</td>
			<td>712-605-153</td>
			<td>Secondary antibody, dilution 1:100</td>
		</tr>
		<tr>
			<td>Vecta Shield</td>
			<td>Vector Laboratories</td>
			<td>H-1000</td>
			<td></td>
		</tr>
		<tr>
			<td>SlowFate Gold</td>
			<td>Invitrogen</td>
			<td>S36937</td>
			<td></td>
		</tr>
		<tr>
			<td>Secure Seal Spacer</td>
			<td>Grace Biolabs</td>
			<td></td>
			<td>Contact company for ordering</td>
		</tr>
		<tr>
			<td>Microscope cover glass 22 X 60 mm</td>
			<td>Marienfeld</td>
			<td>101152</td>
			<td></td>
		</tr>
		<tr>
			<td>Microscope cover glass 22 x 22 mm</td>
			<td>Roth</td>
			<td>H874</td>
			<td></td>
		</tr>
		<tr>
			<td>Stereo Microscope, Leica MZ6</td>
			<td>Leica</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Confocal laser scanning microscope LSM710</td>
			<td>Zeiss</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Immersol</td>
			<td>Zeiss</td>
			<td>518 F</td>
			<td>Immersion oil for fluorescence-microscopy, halogen free</td>
		</tr>
		<tr>
			<td>Immersol</td>
			<td>Zeiss</td>
			<td>W 2010</td>
			<td>Immersion fluid for water-immersion objectives, halogen free</td>
		</tr>
		<tr>
			<td>R56F03-GAL4 (EG)</td>
			<td>Bloomington Stock Center</td>
			<td>39157</td>
			<td>GAL4 driver</td>
		</tr>
		<tr>
			<td>R86E01-GAL4 (ALG)</td>
			<td>Bloomington Stock Center</td>
			<td>45914</td>
			<td>GAL4 driver</td>
		</tr>
		<tr>
			<td>hspFlpPestOpt; UAS-FRT-stop-FRT-myr-smGFP-HA, UAS-FRT-stop-FRT-myr-smGFP-FLAG, UAS-FRT-stop-FRT-myr-smGFP-V5</td>
			<td>Bloomington Stock Center</td>
			<td>64085</td>
			<td>UAS reporter (https://bdscweb.webtest.iu.edu/stock/misc/mcfo.php)</td>
		</tr>
		<tr>
			<td>Multi Time Macro</td>
			<td>Zeiss</td>
			<td></td>
			<td>Software for automated scanning</td>
		</tr>
	</tbody>
</table>

Source: Batelli, S., et al. <a href="https://app.jove.com/v/56177">Application of MultiColor FlpOut Technique to Study High Resolution Single Cell Morphologies and Cell Interactions of Glia in Drosophila.</a>&#160;J. Vis. Exp. (2017).
This video demonstrates the immunofluorescence staining of a transgenic Drosophila brain for single-cell imaging of glial cells. The brain expresses membrane-targeted proteins fused with different combinations of antigenic epitopes under the control of a glial-specific recombinase system. The isolated and fixed brains are stained with primary antibodies specific to the antigenic epitopes, followed by fluorophore-conjugated secondary antibodies. This labeling enables the simultaneous imaging of different glial cell subpopulations across various brain regions.

<img alt="Figure 1" src="/files/ftp_upload/23204/23204_Figure1.jpg" /> 
Figure 1: Crossing scheme for the MCFO technique.&#160;Schematic of the MCFO technique. Homozygousvirgins carrying the MCFO cassette and the hsp-Flp (hsp-Flp; 10XUAS-FRT-stop-FRT-myr-smGFP-HA,10XUAS-FRT-stop-FRT-myr-smGFP-FLAG, 10XUAS-FRT-stop-FRT-myr-smGFP-V5) are crossed with specific homozygous GAL4 driver males. The F1 generation is then heat shocked. According to the number of FRT-stop-FRT c...

Source: Batelli, S., et al. Application of MultiColor FlpOut Technique to Study High Resolution Single Cell Morphologies and Cell Interactions of Glia in ...

Begin with brains from transgenic Drosophila flies, containing different glial cell types harboring a cell-specific recombinase system.
It drives the expression of a cell surface protein fused to different antigenic epitopes on the same type of cells.
Treat the tissue with a fixative to cross-link proteins and preserve the tissue architecture.
Wash to remove excess fixative.
Add blocking proteins to mask non-specific binding sites to reduce background staining.
Incubate the tissue with a primary antibody cocktail that binds to the different epitopes expressed on glial cells.
Wash to remove unbound primary antibodies.
Incubate with fluorophore-conjugated secondary antibodies that bind to the primary antibodies.
Wash to remove unbound secondary antibodies.
Mount the brain inside an imaging spacer and place a coverslip. The spacer creates a chamber for the tissue, preserving its three-dimensional structure.
Different cells of the same glial type labeled with different fluorophore-conjugated antibodies allow an understanding of cell-cell interactions.

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视频: Immunofluorescence Staining of Drosophila Brains for the Single-Cell Imaging of Glial Cells - 实验

Sequential Immunofluorescence and Immunohistochemistry on Cryosectioned Zebrafish Embryos

Investigation of intercellular interactions often requires discrete labeling of specific cell populations and precise protein localization. The zebrafish embryo is an excellent tool for examining such interactions with an in vivo model. Whole-mount immunohistochemical and immunofluorescence assays are frequently applied in zebrafish embryos to assess protein expression. However, it can be difficult to achieve accurate mapping of co-localized proteins in three-dimensional space. In addition, some studies may require the use of two antibodies that are not compatible with the same technique (e.g., antibody 1 is only suitable for immunohistochemistry and antibody 2 is only suitable for immunofluorescence). The purpose of the method described herein is to perform sequential immunofluorescence and/or immunohistochemistry on individual cryosections derived from early-stage zebrafish embryos. Here we describe the use of sequential rounds of immunofluorescence, imaging, immunohistochemistry, imaging for a single cryosection in order to achieve precise identification of protein expression at the single-cell level. This methodology is suitable for any study in early-stage zebrafish embryos that requires accurate identification of multiple protein targets in individual cells.

This protocol demonstrates sequential immunofluorescence and immunohistochemistry on cryosections from early-stage zebrafish embryos enabling precise colocalization analyses in specific cell populations.

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Investigation of intercellular interactions often requires discrete labeling of specific cell populations and precise protein localization. The zebrafish ...

Immunofluorescence Staining of Drosophila Brains for the Single-Cell Imaging of Glial Cells

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Immunofluorescence Staining of Drosophila Brains for the Single-Cell Imaging of Glial Cells