The authors thank members of the Veraksa laboratory for helpful comments on the manuscript and suggestions for protocol improvements. A.V. was supported by the NIH grants GM105813 and NS096402. L.Y. was supported by the University of Massachusetts Boston Sanofi Genzyme Doctoral Fellowship.

1. Preparation of 5 L Fly Cages (to Fit 15 cm Plates)
<ol>
	<li>Obtain the materials needed: 5-quart (4.7-L) container with lid (Figure 1A), nylon mesh, and a razor blade.</li>
	<li>Mark a 12 cm diameter circle and cut a hole in the bottom of the container using the razor blade (Figure 1B). Cut a 15 cm diameter hole in the lid (Figure 1C).</li>
	<li>Cut nylon mesh into 25 x 25 cm squares.</li>
	<li>Place the mesh over the top rim ...

<ol>
	<li>Veraksa, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Regulation+of+developmental+processes:+insights+from+mass+spectrometry-based+proteomics.">Regulation of developmental processes: insights from mass spectrometry-based proteomics.</a> Wiley Interdiscip Rev Dev Biol. 2 (5), 723-734 (2013).</li><li>Gavin, A. C., Maeda, K., Kuhner, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Recent+advances+in+charting+protein-protein+interaction:+mass+spectrometry-based+approaches.">Recent advances in charting protein-protein interaction: mass spectrometry-based approaches.</a> Curr Opin Biotechnol. 22 (1), 42-49 (2011).</li><li>Arbeitman, M. N., 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=Gene+expression+during+the+life+cycle+of+Drosophila+melanogaster.">Gene expression during the life cycle of Drosophila melanogaster.</a> Science. 297 (5590), 2270-2275 (2002).</li><li>Soeller, W. C., Poole, S. J., Kornberg, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=In+vitro+transcription+of+the+Drosophila+engrailed+gene.">In vitro transcription of the Drosophila engrailed gene.</a> Genes Dev. 2 (1), 68-81 (1988).</li><li>Kamakaka, R. T., Kadonaga, J. T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+soluble+nuclear+fraction,+a+highly+efficient+transcription+extract+from+Drosophila+embryos.">The soluble nuclear fraction, a highly efficient transcription extract from Drosophila embryos.</a> Methods Cell Biol. 44, 225-235 (1994).</li><li>Kyriakakis, P., Tipping, M., Abed, L., Veraksa, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Tandem+affinity+purification+in+Drosophila:+The+advantages+of+the+GS-TAP+system.">Tandem affinity purification in Drosophila: The advantages of the GS-TAP system.</a> Fly (Austin). 2 (4), 229-235 (2008).</li><li>Shaffer, C. D., Wuller, J. M., Elgin, S. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Raising+large+quantities+of+Drosophila+for+biochemical+experiments.">Raising large quantities of Drosophila for biochemical experiments.</a> Methods Cell Biol. 44, 99-108 (1994).</li><li>Sisson, J. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Culturing+large+populations+of+Drosophila+for+protein+biochemistry.">Culturing large populations of Drosophila for protein biochemistry.</a> CSH Protoc. 2007, (2007).</li><li>Caravaca, J. M., Lei, E. P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Maintenance+of+a+Drosophila+melanogaster+Population+Cage.">Maintenance of a Drosophila melanogaster Population Cage.</a> J Vis Exp. (109), (2016).</li><li>Yang, L., 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=Minibrain+and+Wings+apart+control+organ+growth+and+tissue+patterning+through+down-regulation+of+Capicua.">Minibrain and Wings apart control organ growth and tissue patterning through down-regulation of Capicua.</a> Proc Natl Acad Sci U S A. 113 (38), 10583-10588 (2016).</li><li>Neumuller, R. A., 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=Stringent+analysis+of+gene+function+and+protein-protein+interactions+using+fluorescently+tagged+genes.">Stringent analysis of gene function and protein-protein interactions using fluorescently tagged genes.</a> Genetics. 190 (3), 931-940 (2012).</li><li>Veraksa, A., Bauer, A., Artavanis-Tsakonas, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Analyzing+protein+complexes+in+Drosophila+with+tandem+affinity+purification-mass+spectrometry.">Analyzing protein complexes in Drosophila with tandem affinity purification-mass spectrometry.</a> Dev Dyn. 232 (3), 827-834 (2005).</li><li>Mukherjee, A., 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=Regulation+of+Notch+signalling+by+non-visual+beta-arrestin.">Regulation of Notch signalling by non-visual beta-arrestin.</a> Nat Cell Biol. 7 (12), 1191-1201 (2005).</li><li>Gilbert, M. M., Tipping, M., Veraksa, A., Moberg, K. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+Screen+for+Conditional+Growth+Suppressor+Genes+Identifies+the+Drosophila+Homolog+of+HD-PTP+as+a+Regulator+of+the+Oncoprotein+Yorkie.">A Screen for Conditional Growth Suppressor Genes Identifies the Drosophila Homolog of HD-PTP as a Regulator of the Oncoprotein Yorkie.</a> Dev Cell. 20 (5), 700-712 (2011).</li><li>Anjum, S. G., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Regulation+of+Toll+Signaling+and+Inflammation+by+beta-Arrestin+and+the+SUMO+Protease+Ulp1.">Regulation of Toll Signaling and Inflammation by beta-Arrestin and the SUMO Protease Ulp1.</a> Genetics. 195 (4), 1307-1317 (2013).</li><li>Degoutin, J. L., 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=Riquiqui+and+minibrain+are+regulators+of+the+hippo+pathway+downstream+of+Dachsous.">Riquiqui and minibrain are regulators of the hippo pathway downstream of Dachsous.</a> Nat Cell Biol. 15 (10), 1176-1185 (2013).</li><li>Zhang, C., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+ecdysone+receptor+coactivator+Taiman+links+Yorkie+to+transcriptional+control+of+germline+stem+cell+factors+in+somatic+tissue.">The ecdysone receptor coactivator Taiman links Yorkie to transcriptional control of germline stem cell factors in somatic tissue.</a> Dev Cell. 34 (2), 168-180 (2015).</li><li>Lemmon, M. A., Schlessinger, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cell+signaling+by+receptor+tyrosine+kinases.">Cell signaling by receptor tyrosine kinases.</a> Cell. 141 (7), 1117-1134 (2010).</li><li>Vincent, J. P., Girdham, C. H., O'Farrell, P. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+cell-autonomous,+ubiquitous+marker+for+the+analysis+of+Drosophila+genetic+mosaics.">A cell-autonomous, ubiquitous marker for the analysis of Drosophila genetic mosaics.</a> Dev Biol. 164 (1), 328-331 (1994).</li><li>Zhai, B., Villen, J., Beausoleil, S. A., Mintseris, J., Gygi, S. P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Phosphoproteome+analysis+of+Drosophila+melanogaster+embryos.">Phosphoproteome analysis of Drosophila melanogaster embryos.</a> J Proteome Res. 7 (4), 1675-1682 (2008).</li><li>Franco, M., Seyfried, N. T., Brand, A. H., Peng, J., Mayor, U. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+novel+strategy+to+isolate+ubiquitin+conjugates+reveals+wide+role+for+ubiquitination+during+neural+development.">A novel strategy to isolate ubiquitin conjugates reveals wide role for ubiquitination during neural development.</a> Mol Cell Proteomics. 10 (5), (2011).</li><li>Ramirez, 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=Proteomic+Analysis+of+the+Ubiquitin+Landscape+in+the+Drosophila+Embryonic+Nervous+System+and+the+Adult+Photoreceptor+Cells.">Proteomic Analysis of the Ubiquitin Landscape in the Drosophila Embryonic Nervous System and the Adult Photoreceptor Cells.</a> PLoS One. 10 (10), 0139083 (2015).</li></ol>

The protocol presented here is a simple and general procedure for setting up Drosophila population cages at medium scale and making whole-cell protein extracts from embryos. The resulting extracts can be used in a variety of downstream applications, such as purification of protein complexes on affinity resins. It is critical to perform the extraction steps on ice and use strong protease inhibition, to minimize protein degradation. As described, the protocol is suitable for isolation of most cytoplasmic and some ...

Genetic screens and, more recently, genomic approaches have revolutionized the study of biological functions. However, important cellular information is encoded in proteins and their ensemble of interacting partners. While traditional genetic modifier screens can identify rate-limiting pathway components and recover indirect interactions, the strength of the proteomic approaches lies in their ability to identify complete immediate interaction networks of proteins of interest. Proteomics is thus a valuable orthogonal method to study biological systems, and complements genomics, transcriptomics, and traditional genetic screens. Affinity purification-mass spectrometry (AP-MS) has proven to be a powerful approach to study protein-protein interactions (PPIs) in their native environment in cells and tissues1,2. This method allows for the identification of direct or indirect interactions at specific developmental stages or tissue contexts, and has been successfully used to identify multiple novel PPIs in a variety of developmental pathways (reviewed in reference1). Despite the undisputed success of PPI studies, most of them have been carried out in cultured cells, in which the &#34;bait&#34; proteins of interest were overexpressed. There are two issues with studying PPIs in cell culture: first, a specific cell line may not provide a full complement of interactions due to lack of expression of certain proteins. Second, high overexpression usually employed in such analyses might lead to artefacts such as protein misfolding or identification of false positive interactions.
Both of these limitations can be overcome by analyzing PPIs in vivo. A limiting step in such experiments is the availability of the starting material for purifying protein complexes. Drosophila melanogaster has long been used as a model for functional analysis, and recently it has also been shown to be an excellent system for studying PPIs in vivo. Drosophila embryogenesis represents a particularly attractive tissue type to study PPIs, because embryos can be easily collected in large quantities, and also because most genes (&#62;88%) are expressed over the course of embryogenesis, thus providing a rich in vivo environment for detecting relevant PPIs3.
Traditionally, biochemical studies in flies utilized very large-scale embryo collections (100-150 g), such as those necessary for purifying functional transcriptional lysates4,5. Previous AP-MS studies in Drosophila also needed large amounts of embryos (5-10 g), because they relied on a two-step purification approach such as tandem affinity purification (TAP), with the associated loss of material at each step6. Large amounts of starting material necessitated setting up embryo collections in large population cages, which can be both expensive (when purchased commercially) and time-consuming to maintain and clean7,8,9.
Recent advances in the development of single-step affinity purification approaches, as well as the increasing sensitivity of mass spectrometers, have reduced the necessary amount of starting material by an order of magnitude. Using tags such as the streptavidin-binding peptide (SBP) or green fluorescent protein (GFP) and starting from less than 1 g of embryos, it is possible to isolate the amounts of the bait protein and interacting components that would be sufficient for identification by mass spectrometry10,11.
The goal of the protocol presented here is to help the researchers overcome a perceived barrier to biochemical analysis of PPIs in vivo. To that end, we provide a simple and inexpensive procedure to collect Drosophila embryos at medium scale (0.5-1 g), followed by one-step preparation of whole-cell protein extracts that are suitable for subsequent analysis by AP-MS or other approaches. Our method relies on the use of custom-made 1-L or 5-L population cages that can be easily produced by any laboratory. Furthermore, the extraction conditions presented here have been validated in several studies, both in cultured cells and in vivo10,12,13,14,15,16,17.

<table border="0" cellpadding="0" cellspacing="0" width="1384">
	<tbody>
		<tr height="21">
			<td height="21" style="height:21px;width:439px;">Leaktite 5-Qt. Natural Multi Mix Container (Pack of 3)</td>
			<td style="width:183px;">Home Depot</td>
			<td style="width:119px;">209330</td>
			<td style="width:644px;">For making 5-L cages.</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:439px;">Leaktite 5-Qt. Natural Multi Mix Lid (Pack of 3)</td>
			<td style="width:183px;">Home Depot</td>
			<td style="width:119px;">209320</td>
			<td style="width:644px;">Diameter 8.37 in. Lids for 5-L cages.</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:439px;">Fisherbrand Petri dishes with clear lid, 100 x 15 mm</td>
			<td style="width:183px;">Fisher Scientific</td>
			<td style="width:119px;">FB0875712</td>
			<td style="width:644px;">Material: Polystyrene. To be used with 1-L cages.</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:439px;">Fisherbrand Petri dishes with clear lid, 150 x 15 mm</td>
			<td style="width:183px;">Fisher Scientific</td>
			<td style="width:119px;">FB0875714</td>
			<td style="width:644px;">Material: Polystyrene. To be used with 5-L cages.</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:439px;">Fisherbrand Petri dishes with clear lid, 60 x 15 mm</td>
			<td style="width:183px;">Fisher Scientific</td>
			<td style="width:119px;">FB0875713A</td>
			<td style="width:644px;">Material: Polystyrene. Used during embryo dechorionation.</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:439px;">Sefar NITEX nylon mesh</td>
			<td style="width:183px;">Sefar</td>
			<td style="width:119px;">03-180/44</td>
			<td style="width:644px;">180 micron, 44% open area, used for fly cages.</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:439px;">Milwaukee 3 in. Hole Dozer Hole Saw with Arbor</td>
			<td style="width:183px;">Home Depot</td>
			<td style="width:119px;">49-56-9670</td>
			<td style="width:644px;">3 inch cutting tool for making 1-L cages.</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:439px;">Nalgene Wide-Mouth Straight-Sided PMP Jars with White Polypropylene Screw Closure</td>
			<td style="width:183px;">Fisher Scientific</td>
			<td style="width:119px;">11-823-33</td>
			<td style="width:644px;">For making 1-L cages. Thermo Scientific cat # 21171000. Alternative 1-L containers can be used.</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:439px;">Red Star Active Dry Yeast, 2 pound pouch</td>
			<td style="width:183px;">Red Star&#160;</td>
			<td style="width:119px;"></td>
			<td style="width:644px;">can be purchased from Amazon.com or other suppliers.</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:439px;">Frozen 100% Apple Juice Concentrate&#160;</td>
			<td style="width:183px;"></td>
			<td style="width:119px;"></td>
			<td style="width:644px;">can be purchased from a grocery store. Has to say &#34;100% apple juice&#34; on the can.</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:439px;">Methyl 4-hydroxybenzoate</td>
			<td style="width:183px;">Acros Organics</td>
			<td style="width:119px;">AC126965000</td>
			<td style="width:644px;">also known as methylparaben or Tegosept. Used as a preservative in AJ plates.</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:439px;">IGEPAL CA-630 for molecular biology, 100 ml</td>
			<td style="width:183px;">Sigma</td>
			<td style="width:119px;">I8896</td>
			<td style="width:644px;">used for preparing lysis buffer.</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:439px;">Nalgene Rapid-Flow Sterile Disposable Filter Units with CN Membrane&#160;</td>
			<td style="width:183px;">Fisher Scientific</td>
			<td style="width:119px;">09-740-2A</td>
			<td style="width:644px;">0.2 &#956;m pore size. Used for filtering 5x lysis buffer. Thermo Scientific cat # 1260020.</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:439px;">CO-RO ROCHE cOmplete Protease Inhibitor Cocktail</td>
			<td style="width:183px;">Sigma</td>
			<td style="width:119px;">11697498001</td>
			<td style="width:644px;">Vial of 20 tablets. Used for protease inhibition in lysis buffer.</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:439px;">Corning SFCA syringe filters&#160;</td>
			<td style="width:183px;">Fisher Scientific</td>
			<td style="width:119px;">09-754-21</td>
			<td style="width:644px;">SFCA membrane, diameter 26 mm, pore size 0.45 &#956;m. Used for filtering final extract samples.</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:439px;">BD&#160;Luer-Lok Disposable Syringes without Needles</td>
			<td style="width:183px;">Fisher Scientific</td>
			<td style="width:119px;">14-823-2A</td>
			<td style="width:644px;">for filtering final extract samples. BD cat # 309604.</td>
		</tr>
		<tr height="63">
			<td height="63" style="height:63px;width:439px;">Bleach</td>
			<td style="width:183px;">Clorox</td>
			<td style="width:119px;"></td>
			<td style="width:644px;">used for embryo dechorionation at 50% (vol/vol) in water, can be purchased at any supermarket. It is important to use the Clorox brand, as other brands may result in incomplete dechorionation or may be toxic for embryos.</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:439px;">Corning Costar Netwell Plates</td>
			<td style="width:183px;">Fisher Scientific</td>
			<td style="width:119px;">07-200-213</td>
			<td style="width:644px;">mesh containers for embryo collections. 74 &#956;m mesh size, 6-well.</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:439px;">Wheaton Dounce Tissue Grinders, capacity 15 ml</td>
			<td style="width:183px;">Fisher Scientific</td>
			<td style="width:119px;">06-435B</td>
			<td style="width:644px;">homogenizer for embryos, with loose and tight pestles. Wheaton cat # 357544.</td>
		</tr>
	</tbody>
</table>

medium-scale preparation of drosophila embryo extracts for proteomic experiments

Analysis of protein-protein interactions (PPIs) has become an indispensable approach to study biological processes and mechanisms, such as cell signaling, organism development, and disease. It is often desirable to obtain PPI information using in vivo material, to gain the most natural and unbiased view of the interaction networks. The fruit fly Drosophila melanogaster is an excellent platform to study PPIs in vivo, and lends itself to straightforward approaches to isolating material for biochemical experiments. In particular, fruit fly embryos represent a convenient type of tissue to study PPIs, due to the ease of collecting animals at this developmental stage and the fact that the majority of proteins are expressed in embryogenesis, thus providing a relevant environment to reveal most PPIs. Here we present a protocol for collection of Drosophila embryos at medium scale (0.5-1 g), which is an ideal amount for a wide range of proteomic applications, including analysis of PPIs by affinity purification-mass spectrometry (AP-MS). We describe our designs for 1 L and 5 L cages for embryo collections that can be easily and inexpensively set up in any laboratory. We also provide a general protocol for embryo collection and protein extraction to generate lysates that can be directly used in downstream applications such as AP-MS. Our goal is to provide an accessible means for all researchers to carry out the analyses of PPIs in vivo.

To illustrate the use of this protocol in a protein complex purification experiment, we generated a homozygous viable fly line, arm-EGFP-ERK, expressing EGFP-tagged Drosophila extracellular signal-regulated kinase (ERK, encoded by the rolled gene) under the control of a ubiquitously expressed armadillo (arm) promoter18,19. The arm promoter is active during most stages of Dr...

Watch this Scientific Journal Video about Medium-scale Preparation of Drosophila Embryo Extracts for Proteomic Experiments at JoVE.com

Medium-scale Preparation of Drosophila Embryo Extracts for Proteomic Experiments

The goal of this protocol is to provide a straightforward and inexpensive approach to collecting Drosophila embryos at medium scale (0.5-1 g) and preparing protein extracts that can be used in downstream proteomic applications, such as affinity purification-mass spectrometry (AP-MS).

Medium-scale Preparation of Drosophila Embryo Extracts for Proteomic Experiments

Analysis of protein-protein interactions (PPIs) has become an indispensable approach to study biological processes and mechanisms, such as cell signaling, ...

The overall goal of this experiment, is to provide a straightforward and inexpensive approach to collecting Drosophilia Embryos at medium scale. And preparing protein extracts that can be used in downstream Proteomic applications, such as affinity purification mass spectrometry. This method can help answer key questions in the fields of cell signaling and developmental biology.For example, how specific protein, protein interactions carry out cell communication during organism development. The main advantage of this technique, is that it's an easy and inexpensive method to generate a Drosophila embryo Lysis. Which can be used for downstream applications like protein affinity purification.Traditionally, researchers collected Drosophila embryos in very large population cages. But we present a user friendly procedure to collect embryos in medium sized cages that can be easily set up in any lab. After preparing five liter containers and cutting 25 by 25 centimeter squares of nylon mesh, according to the text protocol, place the mesh over the container and press down with the lid.Ensure the mesh is tight and the lid is not tilted. The cage is now ready to be populated with flies. Following the preparation of one liter plastic jars and 18 by 18 centimeter nylon mesh squares, place the mesh over the top rim of the jar and screw on the lid to tighten.Make sure the mesh is tight and the lid is not tilted. Amplify the transgenic fly lines carry the typed protein of interest. And transfer the bottles every two days until 25 to 30 bottles are accumulated for each fly line.Amplify a control stock in a similar manner. Next, warm apple juice plates to room temperature. Then using a gloved finger, spread some wet yeast paste in the center of the plates.Making an approximately six centimeter circle for a 15 centimeter plate. And a four centimeter circle for a 10 centimeter plate. After anesthetizing the flies, and transferring them into the prepared cages with the mesh facing down, cover the cages with apple juice plates.Allow the flies to wake up. Then turn the cages over and incubate the flies at room temperature for two to three days. Change the plates twice per day, by turning the cage upside down, and while holding the plate to the cage, peel the tape from the plate.Gently tap the whole cage on the bench and quickly swap the old plate for a new one, trying not to allow the flies to escape. Allow flies to lay embryos on fresh apple juice plates overnight, or for any other desired length of time. The following morning, mark and weigh mesh containers for embryo collection.One for each fly line used. Prepare 1x Lysis Buffer in a 50 milliliter tube using previously made reagents, by adding 40 milliliters of water to 10 milliliters of 5x concentrated Lysis Buffer in a 50 milliliter tube. Add 50 microliters of one molar DTT at a final concentration of one mili molar.Mix well and divide the solution between two 50 milliliter tubes. To one of the tubes add one protease inhibitor tablet. And place the tube on a rotator at four degrees Celsius for 30 minutes.While the tablet is dissolving, start collecting the embryos by marking the apple juice plates on the cages, with the genotypes of fly lines used. And swap the plates for fresh ones. Add enough water to cover each apple juice plate.Then with a soft paintbrush, gently dislodge the embryos from the plate. Pour the embryos into the previously weighed and marked mesh container and drain the excess water. Then briefly blot the mesh on paper towels to remove the excess water.To dechorionate the embryos, half fill a six centimeter Petri dish with 50%bleach. Then prepare two larger Petri dishes with water. Immerse the mesh container with embryos, in 50%bleach for 90 seconds.Gently tap the mesh during incubation a couple of times, to suspend the embryos in the bleach solution. At the end of the incubation, use water to wash the mesh container in each of the two dishes, for about 10 seconds. Then use 18.2 megohm centimeter water in a squirt bottle, to thoroughly rinse the mesh container, including the sides and the outside.No smell of bleach should be detected after a thorough wash. Blot the mesh container on paper towels. Then weigh the mesh container, with the embryos and subtract the weight of the empty container.Record the resulting weight of the embryos. To prepare embryo extract, add one milliliter of Lysis Buffer with protease inhibitors, to a Dounce glass homogenizer and keep it on ice. Then transfer the embryos from the mesh container into the homogenizer.Use one milliliter of Lysis Buffer to wash off the remaining embryos on the mesh. And add the embryos and buffer to the material in the homogenizer. Then let the embryos settle down to the bottom of the homogenizer and carefully aspirate the supernatant.Next, add Lysis Buffer with protease inhibitors to the homogenizer, aiming for five to six milliliters of Lysis Buffer per gram of embryos. Then insert a loose fitting pestle to homogenize the embryos with four to six strokes. During the first strokes, there will be more resistance.Try to move the pestle in a continuous motion, to avoid splashing the solution. Then switch to a tight fitting pestle. And homogenize the embryos with eight to 10 strokes.Incubate the homogenid on ice for 20 minutes. Then transfer the homogenid into micro centrifuge tubes. And centrifuge at 13, 000 time G and four degrees Celsius for 15 minutes.While avoiding the pellets in the very top lipid layer, transfer the supernatants into fresh micro centrifuge tubes on ice. After repeating the centrification use a one milliliter tip to carefully collect the supernatants. And transfer them into chilled, 10 milliliter syringes, with 045 micrometer filters attached.Push all of the solution into labeled two milliliter micro centrifuge tubes on ice. Snap freeze the samples in liquid Nitrogen and store them at negative 80 degrees Celsius. Or use immediately for protein purification experiments.Using the protocol described in this video, Lysates were prepared from Drosophila embryos ubiquitously expressing the EGFP-ERK protein, under control of the arm-odillo promoter. The expression of protein was confirmed by Western Blotting for total ERK protein to simultaneously detect the levels of endogenous and transgenic EGFP-ERK, migrating at 42 kilodaltons and 69 kilodaltons respectively. A single band, corresponding to untagged endogenous ERK was detected in the yellow white control line, confirming a successful extraction of ERK and EGFP-ERK from embryos.To test whether the extraction protocol is suitable for subsequent purification of tagged protein, extracts from the yellow white, and arm-EGFP-ERK flies, were subjected to affinity purification, using GFP Agarose Beads. Silver staining of samples run on a gradient SDS-PAGE, show successful purification of the bait protein EGFP-ERK. Besides EGFP-ERK, the experimental lane contained additional bands, not observed in the control sample, suggesting that the purification recovered potential ERK interacting proteins.Once mastered, the embryo collection and the extraction steps, can be done in approximately two hours. While attempting this procedure it's important to remember to perform the extraction steps on ice. And to use protease inhibitors to minimize protein degradation.After watching this video, you should have a good understanding of how to set up Drosophila population cages at medium scale. And make whole cell protein extracts from embryos.

medium-scale-preparation-drosophila-embryo-extracts-for-proteomic

Research

JoVE Journal

Developmental Biology

7.8K visualizações.  University of Massachusetts Boston. The overall goal of this experiment, is to provide a straightforward and inexpensive approach to collecting Drosophilia Embryos at medium scale. And preparing protein extracts that can be used in downstream Proteomic applications, such as affinity purification mass spectrometry. This method can help answer key questions in the fields of cell signaling and developmental biology.For example, how specific protein, protein interactions carry out cell communication during organism developme...