We appreciate and would like to thank the Howard Hughes Medical Institute for the HHMI Professor award to U.B. which made this project possible. We thank the college at the University of California, Los Angeles for providing facilities and teaching infrastructure support for this work. The work was also supported with funding from Midwestern University and a generous donation from the Charity Fidelity Gift Fund. We thank John VandenBrooks for comments on the manuscript and Krista Pearman for her technical assistance.

This procedure is a 2 day procedure.
Day 1 (2 hr + dissecting time)
1. Pupal Eye Disc Dissection
<ol>
	<li>Select a pupa for dissection. 
	NOTE: The age of the pupa to be dissected will be determined by the experimental needs. However, if examining cell morphology, this is frequently done at 42 hr after puparium formation (APF) at 25 &#176;C, which is the age of the pupae shown in the video. Collect white pupae (considered 0 hr APF) with a wetted paintbrush and arrange them in chronological order (based on collection time) in a new fly food vial maintained at 25 &#176;C. Dissect the aged pupae in this same chronological order to keep the time differences between pupae as close as possible.</li>
	<li>Transfer the pupa into a drop of phosphate-buffered saline (PBS, pH 7.4, see materials for recipe) on a silicone dissecting plate.</li>
	<li>Hold the top of the pupal case with forceps and pierce and open the lower portion of the pupal case with a pair of sharp forceps. Remove the pupa from the case in the newly formed hole.</li>
	<li>Make a diagonal cut with scissors, mid-thorax, in the pupa. Remove the debris or transfer the pupa head to a new drop of PBS. Clean using the pipette blower tube (see materials and Figure 1 for details) and add additional PBS as needed. Make sure to avoid dehydration.</li>
	<li>Securely grip the top of the pupal head cuticle with a pair of forceps. Using the tip of the blower tube, gently push on the pupal case to extrude the brain and other tissues, including the eye discs, out of the pupal case. Be sure to avoid grabbing any tissue within the cuticle.</li>
	<li>Using the blower tube filled with PBS, gently blow the fat body tissue and other debris out of the head case to clearly separate and identify the brain and eye discs. 
	NOTE: Keeping the brain attached to the pupal head case will allow the researcher to use the head case as a &#8220;handle&#8221; for future manipulation of the tissue without damaging the eye discs or brain. However, it is common to dislodge the brain and eye discs from the head case and this is not detrimental to the overall procedure and results. It often takes multiple attempts of blowing and pushing to successfully extract the eye discs and brain from within the pupal head case and so that they are clearly separate from surrounding tissue. The cleaner and more separate one can get the eye discs from the surrounding tissue will help prevent extraneous tissue from fixing to the eye discs.</li>
	<li>Following dissection, immediately transfer the tissue to a 3 well glass dish on ice with 0.5 ml of Fix solution (see materials). Float the tissue on the surface of the Fix solution for a few minutes (typically the time it takes to dissect the next set of eye discs). 
	NOTE: If this is not the first eye disc to be dissected in this round of dissection, completely submerge the previous eye disc into the Fix solution. If performing special staining procedures (e.g., reactive oxygen species, lysosomes, etc.) this must be done prior to fixation. In order to do this, store the dissected eye discs in ice-cold PBS prior to continuing with the appropriate staining protocol.</li>
	<li>Following dissection and submersion of all eye discs being dissected, move the 3 well glass dish to a rocker and rock at room temperature for 30 min.</li>
</ol>
2. Immunostaining
<ol>
	<li>Carefully remove the Fix solution and add 0.5 ml of PBS with 0.3% Triton X-100 (0.3% PBT, see materials) and wash the tissue on a rocker for 10 min. Repeat this step three more times for a total of 4 washes (10 min each). 
	NOTE: Careful removal of the solution from the well can be performed under a dissecting microscope to prevent tissue damage or loss. The solution can be aspirated carefully with a pipet; we prefer a fine-tipped, disposable transfer pipet that has had the opening flattened to reduce the chance of aspirating tissue.</li>
	<li>At the end of the 4th wash, remove the wash and add 0.5 ml block solution (see materials) to the well and incubate for 30 min. 
	NOTE: This time frame can be extended according to your needs.</li>
	<li>At the end of the 30 min block time, pipet 10 &#956;l of Primary Antibody Solution (diluted in Block solution) into the appropriate number of wells in a microwell plate. 
	NOTE: One well of a microwell plate will accommodate about 4 pairs of eye discs attached to the pupal case or 8 isolated pairs of eye discs with brains attached. The primary antibodies used in this protocol for the representative data are anti-phosphotyrosine (1:500 dilution) and anti-Cut (1:200 dilution).</li>
	<li>Transfer the dissected tissue into the microwell plate wells filled with the Primary Antibody Solution from the 3 well glass dish.</li>
	<li>Place the microwell plate on a wetted paper towel (to prevent dehydration) in an empty pipet tip box (or other similar container) and store at 4 &#176;C overnight.</li>
</ol>
Day 2 (4 hr + mounting time)&#160;
<ol start="6">
	<li>Transfer the tissue from the microwell plate to a new 3 well glass dish with 0.3% PBT (&#8776;0.5 ml) and wash the tissue for 10 min on the rocker. Repeat this step three more times for a total of 4 washes (10 min each)</li>
	<li>Remove the last wash and add 0.5 ml of Block solution to the well. Block for 30 min. 
	NOTE: This time frame can be extended according to your needs.</li>
	<li>Remove the Block solution and add 0.5 ml of the Secondary Antibody Solution (made from fluorescently labeled antibodies appropriate to your primary antibody and fluorescent wavelength, diluted in Block solution) to the well and protect the 3 well glass dish from light with a cover or aluminum foil and incubate for at least 2 hr at room temperature. 
	NOTE: All subsequent steps should be similarly protected from light exposure. This incubation can be extended to overnight at 4 &#176;C, in a setup similar to the Primary Antibody incubation, but it can also be performed in a 3 well glass dish covered with laboratory film, or a microwell plate if antibody conservation is desired.</li>
	<li>At end of the antibody incubation, remove the Secondary Antibody Solution and add 0.5 ml of 0.3% PBT to the well and wash on the rocker for 10 min. Repeat this step for a total of 4 washes (10 min each). 
	NOTE: If DAPI staining is desired, before starting the first wash, add 0.5 &#956;l of DAPI stock solution (see materials) to the 500 &#956;l of PBT that will be used for the first wash (1:1,000 dilution).</li>
</ol>
3. Mounting&#160;
<ol>
	<li>At the end of the last wash, mount the antennal/eye discs on a slide using 70% glycerol or PBS as a medium to remove the brain and other unwanted tissues in a pool on one side of the slide.</li>
	<li>Carefully move the tissue using hydrostatic pressure between the forceps, or very gently with a forceps tip, and line up the eye discs in a column towards the center of the slide.</li>
	<li>Remove all extraneous glycerol or PBS from around the tissue (using wicking action of a laboratory wipe or the forceps work for this).</li>
	<li>Place a small amount (&#8776;10 &#956;l) of mounting medium along one side of the eye disc column and place a coverslip on the tissue so as to spread the mounting medium onto the eye discs.</li>
	<li>Let slide sit for 1 to 2 min to allow the tissue/mounting medium to spread out completely.</li>
	<li>Wipe any extra mounting medium off from around the edges of the coverslip and seal it with clear nail polish.</li>
	<li>Capture fluorescent images of the eye discs using confocal microscopy.</li>
</ol>

<ol>
	<li>Ready, D. F., Hanson, T. E., Benzer, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Development+of+the+Drosophila+retina,+a+neurocrystalline+lattice.">Development of the Drosophila retina, a neurocrystalline lattice.</a> Dev Biol. 53 (2), 217-240 (1976).</li><li>Wolff, T., Ready, D. F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+beginning+of+pattern+formation+in+the+Drosophila+compound+eye:+the+morphogenetic+furrow+and+the+second+mitotic+wave.">The beginning of pattern formation in the Drosophila compound eye: the morphogenetic furrow and the second mitotic wave.</a> Development. 113 (3), 841-850 (1991).</li><li>Carthew, R. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Pattern+formation+in+the+Drosophila+eye.">Pattern formation in the Drosophila eye.</a> Curr Opin Genet Dev. 17 (4), 309-313 (2007).</li><li>Bao, S., Cagan, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Preferential+adhesion+mediated+by+Hibris+and+Roughest+regulates+morphogenesis+and+patterning+in+the+Drosophila+eye.">Preferential adhesion mediated by Hibris and Roughest regulates morphogenesis and patterning in the Drosophila eye.</a> Dev cell. 8 (6), 925-935 (2005).</li><li>Grzeschik, N. A., Knust, E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=IrreC/rst-mediated+cell+sorting+during+Drosophila+pupal+eye+development+depends+on+proper+localisation+of+DE-cadherin.">IrreC/rst-mediated cell sorting during Drosophila pupal eye development depends on proper localisation of DE-cadherin.</a> Development. 132 (9), 2035-2045 (2005).</li><li>Sprecher, S. G., Desplan, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Switch+of+rhodopsin+expression+in+terminally+differentiated+Drosophila+sensory+neurons.">Switch of rhodopsin expression in terminally differentiated Drosophila sensory neurons.</a> Nature. 454 (7203), 533-537 (2008).</li><li>Zuker, C. S., Cowman, A. F., Rubin, G. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Isolation+and+structure+of+a+rhodopsin+gene+from+D.+melanogaster.">Isolation and structure of a rhodopsin gene from D. melanogaster.</a> Cell. 40 (4), 851-858 (1985).</li><li>Voas, M. G., Rebay, I. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Signal+integration+during+development:+insights+from+the+Drosophila+eye.">Signal integration during development: insights from the Drosophila eye.</a> Dev Dyn. 229 (1), 162-175 (2004).</li><li>Hsiao, H. Y., 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=Dissection+and+immunohistochemistry+of+larval,+pupal+and+adult+Drosophila+retinas.">Dissection and immunohistochemistry of larval, pupal and adult Drosophila retinas.</a> J Vis Exp. , 4347 (2012).</li><li>Call, G. B., 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=Genomewide+clonal+analysis+of+lethal+mutations+in+the+Drosophila+melanogaster+eye:+comparison+of+the+X+chromosome+and+autosomes.">Genomewide clonal analysis of lethal mutations in the Drosophila melanogaster eye: comparison of the X chromosome and autosomes.</a> Genetics. 177 (2), 689-697 (2007).</li><li>Chen, 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=Discovery-based+science+education:+functional+genomic+dissection+in+Drosophila+by+undergraduate+researchers.">Discovery-based science education: functional genomic dissection in Drosophila by undergraduate researchers.</a> PLoS Biol. 3 (2), 59 (2005).</li><li>Wolff, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Dissection+techniques+for+pupal+and+larval+Drosophila+eyes.">Dissection techniques for pupal and larval Drosophila eyes.</a> CSH Protoc. 2007, (2007).</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> J Vis Exp. 37, 1936 (2010).</li><li>Xu, T., Rubin, G. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Analysis+of+genetic+mosaics+in+developing+and+adult+Drosophila+tissues.">Analysis of genetic mosaics in developing and adult Drosophila tissues.</a> Development. 117 (4), 1223-1237 (1993).</li><li>Duffy, J. B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=GAL4+system+in+Drosophila:+a+fly+geneticist's+Swiss+army+knife.">GAL4 system in Drosophila: a fly geneticist's Swiss army knife.</a> Genesis. 34 (1-2), 1-15 (2002).</li></ol>

The authors have nothing to disclose.

While it appears that the process is simple and easy to perform, in reality, this technique requires a great deal of practice to master. Routinely, we start students off by learning to dissect and mount third instar eye discs12, which are much easier to work with. This practice helps to develop an appropriate dissection position of the arms, hands and fingers13 so that manipulation of the forceps under the dissecting microscope is stable, easy and experienced. In essence, the practice period shou...

The fields of developmental and cell biology have been greatly impacted by the model organism: Drosophila melanogaster. Within this model, studies of the eye disc have contributed a great deal of knowledge concerning signaling, cell biology and other areas. The late third larval instar eye disc has been studied extensively and is a powerful model to utilize, as it gives a snapshot of a series of developmental periods, each with its own unique signaling molecules and processes, as the morphogenetic furrow progresses across the eye disc8. However, there is a need to further expand our understanding of developmental processes into the pupal phase of development. While there have been studies on the pupal eye disc3-7, our knowledge does not approach the breadth of work that has been performed on the third instar eye disc. This is due, in part, to the greater difficulty in dissecting the pupal eye disc. Therefore, a presentation of the proper method of dissection could greatly expand research in this area.
While there are stages within pupal eye disc development that are easily dissected, particularly around the mid-pupal period, other time periods are much more challenging to dissect. This protocol represents one method for dissecting pupal eye discs that can be universally used for all pupal developmental time frames. This protocol can be used as an alternative to another protocol9 that shows an easier and faster method to dissect eye discs from the midpupal time points. This protocol was originally filmed and developed for training advanced undergraduate students in the UCLA Undergraduate Research Consortium in Functional Genomics (URCFG)10,11 in the technique of pupal eye dissection. Many undergraduate students were able to utilize this video and method to learn this challenging technique.

<table border="0" cellpadding="0" cellspacing="0">
	<tbody>
		<tr>
			<td>Phosphate-buffered saline (PBS, pH 7.4)</td>
			<td></td>
			<td></td>
			<td>80g NaCl, 2g&#160; KCl, 14.4g Na2HPO4, 2.4g KH2PO4, Bring volume to 1 l, adjust the pH to 7.4, autoclave or filter sterilize, dilute to 1X PBS with autoclaved ddH2O before using.</td>
		</tr>
		<tr>
			<td>Triton X-100</td>
			<td>Promega</td>
			<td>H5142</td>
			<td>Caution: Irritant! Wear gloves.</td>
		</tr>
		<tr>
			<td>0.3% PBT</td>
			<td></td>
			<td></td>
			<td>1.5 ml of Triton X-100, 500 ml 1X PBS.</td>
		</tr>
		<tr>
			<td>37% formaldehyde solution</td>
			<td>Fisher Scientific</td>
			<td>F75P1GAL</td>
			<td>Caution: Toxic, probable human carcinogen! Wear gloves.&#160;</td>
		</tr>
		<tr>
			<td>Fix Solution</td>
			<td></td>
			<td></td>
			<td>(&#8776;4% Formaldehyde in PBS) 50 &#956;l of 37% Formaldehyde, 450 &#956;l 1XPBS, make fresh before use</td>
		</tr>
		<tr>
			<td>Normal goat serum</td>
			<td>Rockland antibodies &#38; assays</td>
			<td>B304</td>
			<td>Aliquot in 1 ml volumes and store at -80C</td>
		</tr>
		<tr>
			<td>Block Solution</td>
			<td></td>
			<td></td>
			<td>10% NGS in PBT.&#160; This can be made and stored at 4 &#176;C for a few days prior to use.</td>
		</tr>
		<tr>
			<td>DAPI stock solution</td>
			<td>Life Technologies</td>
			<td>D3571</td>
			<td>For coutnerstaining nuclei. Prepare a 1 mg/ml solution with ddH2O.</td>
		</tr>
		<tr>
			<td>VectaShield Mounting Medium</td>
			<td>Vector Labs</td>
			<td>H-1000</td>
			<td>Mounting medium</td>
		</tr>
		<tr>
			<td>Glycerol</td>
			<td>Sigma</td>
			<td>G5516</td>
			<td>For mounting. Prepare 70% dilution with ddH2O.</td>
		</tr>
		<tr>
			<td colspan="4">Equipment</td>
		</tr>
		<tr>
			<td>Nutating mixer</td>
			<td>VWR</td>
			<td>82007-202</td>
			<td>Used to rock tissue in 3 well glass dish</td>
		</tr>
		<tr>
			<td>SylGard 182 Silicone Elastomer Kit</td>
			<td>Krayden</td>
			<td>NC9897184</td>
			<td>Used to make silicone dissection dish</td>
		</tr>
		<tr>
			<td>Silicone dissecting dish</td>
			<td></td>
			<td></td>
			<td>Mix Sylgard elastomer kit (above) according to directions gently (to avoid bubbles). Pour mixture into Petri dish (any size). Allow SylGard to cure overnight in 37 &#176;C incubator.</td>
		</tr>
		<tr>
			<td>3 well glass dish</td>
			<td>Corning</td>
			<td>7220-85</td>
			<td>The 3 well variety of these are no longer available, this is the 9 well product.</td>
		</tr>
		<tr>
			<td>72 well microwell minitray</td>
			<td>Nunc</td>
			<td>438733</td>
			<td></td>
		</tr>
		<tr>
			<td>Sharp forceps (Dumont #55)</td>
			<td>Fine Science Tools</td>
			<td>11255-20</td>
			<td></td>
		</tr>
		<tr>
			<td><a name="RANGE!A19">Vannas-type Micro Scissors, Straight, 5mm blade</a></td>
			<td>Ted Pella</td>
			<td>1346</td>
			<td></td>
		</tr>
		<tr>
			<td>100 mm Borosilicate glass capillaries</td>
			<td>World Precision Instruments</td>
			<td>1B100-4</td>
			<td>Pull with needle puller to make fine point tip that allows a small stream of PBS to flow.</td>
		</tr>
		<tr>
			<td>Disposable Transfer Pipets, Fine Tip</td>
			<td>Samco Scientific</td>
			<td>231</td>
			<td></td>
		</tr>
		<tr>
			<td colspan="4">Tubing dimensions given are inner diameter (ID) x outer diameter (OD) x wall thickness in inches</td>
		</tr>
		<tr>
			<td>PVC tubing (1/8 x 3/16 x 1/32)</td>
			<td>Nalgene</td>
			<td>8000-0010</td>
			<td rowspan="3">Use these with pulled needle to assemble the blower tube as shown in Figure 2.</td>
		</tr>
		<tr>
			<td>Tygon Silicone tubing (3/32 x 5/32 x 1/32)</td>
			<td>Saint Gobain Performance Plastics</td>
			<td>ABW00004</td>
		</tr>
		<tr>
			<td>Tygon Silicone tubing (1/32 x 3/32 x 1/32)</td>
			<td>Saint Gobain Performance Plastics</td>
			<td>ABW00001</td>
		</tr>
	</tbody>
</table>

dissection and mounting of drosophila pupal eye discs

The Drosophila melanogaster eye disc is a powerful system that can be used to study many different biological processes. It contains approximately 800 separate eye units, termed ommatidia1. Each ommatidium contains eight neuronal photoreceptors that develop from undifferentiated cells following the passage of the morphogenetic furrow in the third larval instar2. Following the sequential differentiation of the photoreceptors, non-neuronal cells develop, including cone and pigment cells, along with mechanosensory bristle cells3. Final differentiation processes, including the structured arrangement of all the ommatidial cell types, programmed cell death of undifferentiated cell types and rhodopsin expression, occurs through the pupal phase4-7. This technique focuses on manipulating the pupal eye disc, providing insight and instruction on how to dissect the eye disc during the pupal phase, which is inherently more difficult to perform than the commonly dissected third instar eye disc. This technique also provides details on immunostaining to allow the visualization of various proteins and other cell components.

As an example of the use of this protocol, results illustrating midpupal (42 hrs APF at 25 &#176;C) eye discs immunostained with different antibodies are presented in Figure 2. By using an antibody directed against phosphotyrosine residues, the membrane of the cells can be observed (Figure 2A). This can be used to identify the regular arrangement of ommatidial cells in the pupal eye following the final patterning processes that occur prior to the midpupal stage. Another representative image depicts the n...

Watch this Scientific Journal Video about Dissection and Mounting of Drosophila Pupal Eye Discs at JoVE.com

Dissection and Mounting of Drosophila Pupal Eye Discs

The goal of this technique is to enable researchers to perform dissection, immunostaining and mounting of pupal eye discs from Drosophila melanogaster of any age.

Dissection and Mounting of Drosophila Pupal Eye Discs

The Drosophila melanogaster eye disc is a powerful system that can be used to study many different biological processes.  It contains approximately 800 ...

dissection-and-mounting-of-drosophila-pupal-eye-discs

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JoVE Journal

Biology

12.1K Views.  University of California at Los Angeles (UCLA). The goal of this technique is to enable researchers to perform dissection, immunostaining and mounting of pupal eye discs from Drosophila melanogaster of any age.

Video: Dissection and Mounting of Drosophila Pupal Eye Discs

Dissection of Drosophila Ovaries

Dissection of Imaginal Discs from 3rd Instar Drosophila Larvae

This protocol demonstrates the dissection technique used for isolating imaginal discs from drosophila larvae at the 3rd instar stage. Methods for fixing the tissue after saying and removing the wing, leg, and eye discs are demonstrated directly on a microscope slide for subsequent visualization.

Drosophila Larval NMJ Dissection

The Drosophila neuromuscular junction (NMJ) is an established model system used for the study of synaptic development and plasticity. The widespread use of the Drosophila motor system is due to its high accessibility. It can be analyzed with single-cell resolution. There are 30 muscles per hemisegment whose arrangement within the peripheral body wall are known. A total of 35 motor neurons attach to these muscles in a pattern that has high fidelity. Using molecular biology and genetics, one can create transgenic animals or mutants. Then, one can study the developmental consequences on the morphology and function of the NMJ. In order to access the NMJ for study, it is necessary to carefully dissect each larva. In this article we demonstrate how to properly dissect Drosophila larvae for study of the NMJ by removing all internal organs while leaving the body wall intact. This technique is suitable to prepare larvae for imaging, immunohistochemistry, or electrophysiology.

This protocol demonstrates how to dissect Drosophila larvae in preparation for immunohistochemistry and/or imaging of the neuromuscular junction.

The Drosophila neuromuscular junction (NMJ) is an established model system used for the study of synaptic development and plasticity. The widespread use ...

Dissection and Staining of Drosophila Larval Ovaries

Many organs depend on stem cells for their development during embryogenesis and for maintenance or repair during adult life. Understanding how stem cells form, and how they interact with their environment is therefore crucial for understanding development, homeostasis and disease. The ovary of the fruit fly Drosophila melanogaster has served as an influential model for the interaction of germ line stem cells (GSCs) with their somatic support cells (niche) 1, 2. The known location of the niche and the GSCs, coupled to the ability to genetically manipulate them, has allowed researchers to elucidate a variety of interactions between stem cells and their niches 3-12.
Despite the wealth of information about mechanisms controlling GSC maintenance and differentiation, relatively little is known about how GSCs and their somatic niches form during development. About 18 somatic niches, whose cellular components include terminal filament and cap cells (Figure 1), form during the third larval instar 13-17. GSCs originate from primordial germ cells (PGCs). PGCs proliferate at early larval stages, but following the formation of the niche a subgroup of PGCs becomes GSCs 7, 16, 18, 19. Together, the somatic niche cells and the GSCs make a functional unit that produces eggs throughout the lifetime of the organism.
Many questions regarding the formation of the GSC unit remain unanswered. Processes such as coordination between precursor cells for niches and stem cell precursors, or the generation of asymmetry within PGCs as they become GSCs, can best be studied in the larva. However, a methodical study of larval ovary development is physically challenging. First, larval ovaries are small. Even at late larval stages they are only 100&mu;m across. In addition, the ovaries are transparent and are embedded in a white fat body. Here we describe a step-by-step protocol for isolating ovaries from late third instar (LL3) Drosophila larvae, followed by staining with fluorescent antibodies. We offer some technical solutions to problems such as locating the ovaries, staining and washing tissues that do not sink, and making sure that antibodies penetrate into the tissue. This protocol can be applied to earlier larval stages and to larval testes as well.

Dissection and Staining of Drosophila Larval Ovaries

How niches and stem cells form during development is an important question with practical implications. In the Drosophila ovary, germ line stem cells and their somatic niches form during larval development. This video demonstrates how to dissect, stain and mount female gonads from late third instar (LL3) Drosophila larvae.

Many organs depend on stem cells for their development during embryogenesis and for maintenance or repair during adult life. Understanding how stem cells ...

Drosophila Pupal Abdomen Immunohistochemistry

The Drosophila pupal abdomen is an established model system for the study of epithelial morphogenesis and the development of sexually dimorphic morphologies 1-3. During pupation, which spans approximately 96 hours (at 25 &deg;C), proliferating populations of imaginal cells replace the larval epidermis to generate the adult abdominal segments. These imaginal cells, born during embryogenesis, exist as lateral pairs of histoblast nests in each abdominal segment of the larvae. Four pairs of histoblast nests give rise to the adult dorsal cuticle (anterior and posterior dorsal nests), the ventral cuticle (ventral nests) and the spiracles associated with each segment (spiracle nests) 4. Upon puparation, these diploid cells (distinguishable by size from the larger polyploid larval epidermal cells- LECs) begin a stereotypical process of proliferation, migration and replacement of the LECs. Various molecular and genetic tools can be employed to investigate the contributions of genetic pathways involved in morphogenesis of the adult abdomen. Ultimate adult phenotypes are typically analyzed following dissection of adult abdominal cuticles. However, investigation of the underlying molecular processes requires immunohistochemical analyses of the pupal epithelium, which present unique challenges. Temporally dynamic morphogenesis and the interactions of two distinct epithelial populations (larval and imaginal) generate a fragile tissue prone to excessive cell loss during dissection and subsequent processing. We have developed methods of dissection, fixation, mounting and imaging of the Drosophila pupal abdominem epithelium for immunohistochemical studies that generate consistent high quality samples suitable for confocal or standard fluorescent microscopy.

Drosophila Pupal Abdomen Immunohistochemistry

Antibody staining of the Drosophila pupae can enhance genetic analyses of adult abdominal developmental genetics. We present our protocol for dissection, fixation and antibody staining of staged Drosophila pupal abdomen.

The Drosophila pupal abdomen is an established model system for the study of epithelial morphogenesis and the development of sexually dimorphic ...

Imaging Through the Pupal Case of Drosophila melanogaster

The longstanding use of Drosophila as a model for cell and developmental biology has yielded an array of tools. Together, these techniques have enabled analysis of cell and developmental biology from a variety of methodological angles. Live imaging is an emerging method for observing dynamic cell processes, such as cell division or cell motility. Having isolated mutations in uncharacterized putative cell cycle proteins it became essential to observe mitosis in situ using live imaging. Most live imaging studies in Drosophila have focused on the embryonic stages that are accessible to manipulation and observation because of their small size and optical clarity. However, in these stages the cell cycle is unusual in that it lacks one or both of the gap phases. By contrast, cells of the pupal wing of Drosophila have a typical cell cycle and undergo a period of rapid mitosis spanning about 20 hr of pupal development. It is easy to identify and isolate pupae of the appropriate stage to catch mitosis in situ. Mounting intact pupae provided the best combination of tractability and durability during imaging, allowing experiments to run for several hours with minimal impact on cell and animal viability. The method allows observation of features as small as, or smaller than, fly chromosomes. Adjustment of microscope settings and the details of mounting, allowed extension of the preparation to visualize membrane dynamics of adjacent cells and fluorescently labeled proteins such as tubulin. This method works for all tested fluorescent proteins and can capture submicron scale features over a variety of time scales. While limited to the outer 20 &#181;m of the pupa with a conventional confocal microscope, this approach to observing protein and cellular dynamics in pupal tissues in vivo may be generally useful in the study of cell and developmental biology in these tissues.

Imaging Through the Pupal Case of Drosophila melanogaster

This paper demonstrates the use of a fast scanning confocal microscope to image cell behavior directly through the puparium. By leaving the pupal case intact, this method allows observation and measurement of dynamic cell processes at a stage of Drosophila development that is difficult to study directly.

The longstanding use of Drosophila as a model for cell and developmental biology has yielded an array of tools. Together, these techniques have enabled ...

Dissection and Immunostaining of Imaginal Discs from Drosophila melanogaster

A significant portion of post-embryonic development in the fruit fly, Drosophila melanogaster, takes place within a set of sac-like structures called imaginal discs. These discs give rise to a high percentage of adult structures that are found within the adult fly. Here we describe a protocol that has been optimized to recover these discs and prepare them for analysis with antibodies, transcriptional reporters and protein traps. This procedure is best suited for thin tissues like imaginal discs, but can be easily modified for use with thicker tissues such as the larval brain and adult ovary. The written protocol and accompanying video will guide the reader/viewer through the dissection of third instar larvae, fixation of tissue, and treatment of imaginal discs with antibodies. The protocol can be used to dissect imaginal discs from younger first and second instar larvae as well. The advantage of this protocol is that it is relatively short and it has been optimized for the high quality preservation of the dissected tissue. Another advantage is that the fixation procedure that is employed works well with the overwhelming number of antibodies that recognize Drosophila proteins. In our experience, there is a very small number of sensitive antibodies that do not work well with this procedure. In these situations, the remedy appears to be to use an alternate fixation cocktail while continuing to follow the guidelines that we have set forth for the dissection steps and antibody incubations.

Dissection and Immunostaining of Imaginal Discs from Drosophila melanogaster

The adult structures of Drosophila are derived from sac-like structures called imaginal discs. Analysis of these discs provides insight into many developmental processes including tissue determination, compartment boundary establishment, cell proliferation, cell fate specification, and planar cell polarity. This protocol is used to prepare imaginal discs for light/fluorescent microscopy.

A significant portion of post-embryonic development in the fruit fly, Drosophila melanogaster, takes place within a set of sac-like structures called ...

Ex vivo Culture of Drosophila Pupal Testis and Single Male Germ-line Cysts: Dissection, Imaging, and Pharmacological Treatment

During spermatogenesis in mammals and in Drosophila melanogaster, male germ cells develop in a series of essential developmental processes. This includes differentiation from a stem cell population, mitotic amplification, and meiosis. In addition, post-meiotic germ cells undergo a dramatic morphological reshaping process as well as a global epigenetic reconfiguration of the germ line chromatin&#8212;the histone-to-protamine switch.
Studying the role of a protein in post-meiotic spermatogenesis using mutagenesis or other genetic tools is often impeded by essential embryonic, pre-meiotic, or meiotic functions of the protein under investigation. The post-meiotic phenotype of a mutant of such a protein could be obscured through an earlier developmental block, or the interpretation of the phenotype could be complicated. The model organism Drosophila melanogaster offers a bypass to this problem: intact testes and even cysts of germ cells dissected from early pupae are able to develop ex vivo in culture medium. Making use of such cultures allows microscopic imaging of living germ cells in testes and of germ-line cysts. Importantly, the cultivated testes and germ cells also become accessible to pharmacological inhibitors, thereby permitting manipulation of enzymatic functions during spermatogenesis, including post-meiotic stages.
The protocol presented describes how to dissect and cultivate pupal testes and germ-line cysts. Information on the development of pupal testes and culture conditions are provided alongside microscope imaging data of live testes and germ-line cysts in culture. We also describe a pharmacological assay to study post-meiotic spermatogenesis, exemplified by an assay targeting the histone-to-protamine switch using the histone acetyltransferase inhibitor anacardic acid. In principle, this cultivation method could be adapted to address many other research questions in pre- and post-meiotic spermatogenesis.

Ex vivo Culture of Drosophila Pupal Testis and Single Male Germ-line Cysts: Dissection, Imaging, and Pharmacological Treatment

This protocol describes the dissection and cultivation of intact testes and germ-line cysts from Drosophila melanogaster pupae. This method allows microscopic observation of spermatogenesis ex vivo. Furthermore, we describe a pharmacological assay of the effect of inhibitors on specific stages of germ-cell development in pupal testes.

During spermatogenesis in mammals and in Drosophila melanogaster, male germ cells develop in a series of essential developmental processes. This includes ...

Dissection and Flat-mounting of the Threespine Stickleback Branchial Skeleton

The posterior pharyngeal segments of the vertebrate head give rise to the branchial skeleton, the primary site of food processing in fish. The morphology of the fish branchial skeleton is matched to a species' diet. Threespine stickleback fish (Gasterosteus aculeatus) have emerged as a model system to study the genetic and developmental basis of evolved differences in a variety of traits. Marine populations of sticklebacks have repeatedly colonized countless new freshwater lakes and creeks. Adaptation to the new diet in these freshwater environments likely underlies a series of craniofacial changes that have evolved repeatedly in independently derived freshwater populations. These include three major patterning changes to the branchial skeleton: reductions in the number and length of gill raker bones, increases in pharyngeal tooth number, and increased branchial bone lengths. Here we describe a detailed protocol to dissect and flat-mount the internal branchial skeleton in threespine stickleback fish. Dissection of the entire three-dimensional branchial skeleton and mounting it flat into a largely two-dimensional prep allows for the easy visualization and quantification of branchial skeleton morphology. This dissection method is inexpensive, fast, relatively easy, and applicable to a wide variety of fish species. In sticklebacks, this efficient method allows the quantification of skeletal morphology in genetic crosses to map genomic regions controlling craniofacial patterning.

The branchial skeleton, including gill rakers, pharyngeal teeth, and branchial bones, serves as the primary site of food processing in most fish. Here we describe a protocol to dissect and flat-mount this internal skeleton in threespine sticklebacks. This method is also applicable to a variety of other fish species.

The posterior pharyngeal segments of the vertebrate head give rise to the branchial skeleton, the primary site of food processing in fish. The morphology ...

Methods for Staging Pupal Periods and Measurement of Wing Pigmentation of Drosophila guttifera

Diversified species of Drosophila (fruit fly) provide opportunities to study mechanisms of development and genetic changes responsible for evolutionary changes. In particular, the adult stage is a rich source of morphological traits for interspecific comparison, including wing pigmentation comparison. To study developmental differences among species, detailed observation and appropriate staging are required for precise comparison. Here we describe protocols for staging of pupal periods and quantification of wing pigmentation in a polka-dotted fruit fly, Drosophila guttifera. First, we describe the method for detailed morphological observation and definition of pupal stages based on morphologies. This method includes a technique for removing the puparium, which is the outer chitinous case of the pupa, to enable detailed observation of pupal morphologies. Second, we describe the method for measuring the duration of defined pupal stages. Finally, we describe the method for quantification of wing pigmentation based on image analysis using digital images and ImageJ software. With these methods, we can establish a solid basis for comparing developmental processes of adult traits during pupal stages.

Methods for Staging Pupal Periods and Measurement of Wing Pigmentation of Drosophila guttifera

Protocols for staging pupal periods and measurement of wing pigmentation of Drosophila guttifera are described. Staging and quantification of pigmentation provide a solid basis for studying developmental mechanisms of adult traits and enable interspecific comparison of trait development.

Diversified species of Drosophila (fruit fly) provide opportunities to study mechanisms of development and genetic changes responsible for evolutionary ...