This work was supported by a Marie Curie Reintegration Grant (IRG249084). We thank all members of the Kurant laboratory. We also thank E. Suss-Toby at the Interdepartmental Bioimaging facility for excellent technical support.

To follow the dynamics of apoptotic cell clearance in vivo two populations of cells must be labeled: phagocytic cells and apoptotic cells.
To mark phagocytic cell populations we use a Drosophila line containing the simu-cytGFP marker, which labels exclusively phagocytic cells in the embryo: macrophages, glia and ectoderm8. One can use different markers for phagocytic cells, including lines containing a hemocyte-specific Gal4 driver (crq-Gal4) or g...

<ol>
	<li>Kinchen, J. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+model+to+die+for:+signaling+to+apoptotic+cell+removal+in+worm,+fly+and+mouse.">A model to die for: signaling to apoptotic cell removal in worm, fly and mouse.</a> Apoptosis. 15, 998-1006 (2010).</li><li>Kinchen, J. M., Ravichandran, K. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Phagosome+maturation:+going+through+the+acid+test.">Phagosome maturation: going through the acid test.</a> Nat. Rev. Mol. Cell Biol. 9, 781-795 (2008).</li><li>Kinchen, J. M., Ravichandran, K. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Phagocytic+signaling:+you+can+touch,+but+you+can't+eat.">Phagocytic signaling: you can touch, but you can't eat.</a> Curr. Biol. 18, 521-524 (2008).</li><li>Stuart, L. M., Ezekowitz, R. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Phagocytosis:+elegant+complexity.">Phagocytosis: elegant complexity.</a> Immunity. 22, 539-550 (2005).</li><li>Lauber, K., Blumenthal, S. G., Waibel, M., Wesselborg, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Clearance+of+apoptotic+cells:+getting+rid+of+the+corpses.">Clearance of apoptotic cells: getting rid of the corpses.</a> Mol. Cell. 14, 277-287 (2004).</li><li>Henson, P. M., Hume, D. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Apoptotic+cell+removal+in+development+and+tissue+homeostasis.">Apoptotic cell removal in development and tissue homeostasis.</a> Trends Immunol. 27, 244-250 (2006).</li><li>Kurant, E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Keeping+the+CNS+clear:+glial+phagocytic+functions+in+Drosophila.">Keeping the CNS clear: glial phagocytic functions in Drosophila.</a> Glia. 59, 1304-1311 (2011).</li><li>Kurant, E., Axelrod, S., Leaman, D., Gaul, U. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Six-microns-under+acts+upstream+of+Draper+in+the+glial+phagocytosis+of+apoptotic+neurons.">Six-microns-under acts upstream of Draper in the glial phagocytosis of apoptotic neurons.</a> Cell. 133, 498-509 (2008).</li><li>Mergliano, J., Minden, J. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Caspase-independent+cell+engulfment+mirrors+cell+death+pattern+in+Drosophila+embryos.">Caspase-independent cell engulfment mirrors cell death pattern in Drosophila embryos.</a> Development. 130, 5779-5789 (2003).</li><li>van den Eijnde, S. M., 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=Cell+surface+exposure+of+phosphatidylserine+during+apoptosis+is+phylogenetically+conserved.">Cell surface exposure of phosphatidylserine during apoptosis is phylogenetically conserved.</a> Apoptosis. 3, 9-16 (1998).</li></ol>

The authors declare that they have no competing financial interests.

Apoptotic cell clearance is a critical last stage of apoptosis, which is highly dynamic. Therefore real time studies of the process are of utmost importance. Here we describe a protocol that enables monitoring of apoptotic cell clearance in living developing Drosophila embryos. In this procedure, two populations of cells must be marked using specific markers: apoptotic cells and phagocytes. The simu-cytGFP reporter is suitable for monitoring phagocytic macrophages, glia and ectoderm simultaneously ...

The proper elimination of unwanted or aberrant cells through apoptosis and subsequent phagocytosis is crucial for embryonic development as well as for tissue homeostasis in the adult. Phagocytosis of apoptotic cells or apoptotic cell clearance is a highly dynamic process which proceeds in four steps: (1) recruitment of phagocytes to the apoptotic cell ('find-me'), (2) recognition of the cell as a target for phagocytosis ('eat-me') and (3) engulfment, followed by (4) phagosome maturation and degradation of the apoptotic particle1-5. There are two types of phagocytes: 'professional' macrophages and immature dendritic cells, and the 'non-professional' tissue-resident neighboring cells, which are crucial for apoptotic cell clearance during metazoan development6,7 .
In Drosophila development, the elimination of superfluous cells through apoptosis occurs in three main phases, first in the mid to late embryo, then in the mid pupa, and again in the early adult. During embryogenesis apoptotic particles are removed by 'professional' phagocytes, macrophages, and by the 'non-professional' ectoderm and glia8,9 .
In our previous work we have identified a phagocytic receptor, Six-microns-under (SIMU), which is expressed exclusively in phagocytic cells during embryogenesis. Using the simu promoter we generated a specific marker for phagocytic cell populations (simu-cytGFP) which enables us to monitor macrophages, ectoderm and glia simultaneously in a live developing embryo8. In addition, by using specific markers for apoptotic cells in different stages of apoptosis, we are able to follow the dynamics of apoptotic cell clearance in vivo.

<table border="1">
 <tbody>
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 <td></td>
 <td>Reagent</td>
 </tr>
 <tr>
 <td>Annexin V </td>
 <td>Molecular Probes</td>
 <td>A35108</td>
 <td></td>
 </tr>
 <tr>
 <td>PhiPhiLux G2D2</td>
 <td>OncoImmunin</td>
 <td>A304R2G-5</td>
 <td></td>
 </tr>
 <tr>
 <td>LysoTracker</td>
 <td>Molecular Probes</td>
 <td>L-7528</td>
 <td></td>
 </tr>
 <tr>
 <td>Halocarbon oil 700</td>
 <td>Sigma</td>
 <td>H8898</td>
 <td></td>
 </tr>
 <tr>
 <td></td>
 <td></td>
 <td></td>
 <td>Material</td>
 </tr>
 <tr>
 <td>Capillary tubing</td>
 <td>FHC </td>
 <td>30-30-0</td>
 <td></td>
 </tr>
 <tr>
 <td>Cell Strainer</td>
 <td>SPL</td>
 <td>93100</td>
 <td></td>
 </tr>
 <tr>
 <td>Paintbrush</td>
 <td></td>
 <td></td>
 <td></td>
 </tr>
 </tbody>
</table>

live imaging of apoptotic cell clearance during drosophila embryogenesis

The proper elimination of unwanted or aberrant cells through apoptosis and subsequent phagocytosis (apoptotic cell clearance) is crucial for normal development in all metazoan organisms. Apoptotic cell clearance is a highly dynamic process intimately associated with cell death; unengulfed apoptotic cells are barely seen in vivo under normal conditions. In order to understand the different steps of apoptotic cell clearance and to compare 'professional' phagocytes - macrophages and dendritic cells to 'non-professional' - tissue-resident neighboring cells, in vivo live imaging of the process is extremely valuable. Here we describe a protocol for studying apoptotic cell clearance in live Drosophila embryos. To follow the dynamics of different steps in phagocytosis we use specific markers for apoptotic cells and phagocytes. In addition, we can monitor two phagocyte systems in parallel: 'professional' macrophages and 'semi-professional' glia in the developing central nervous system (CNS). The method described here employs the Drosophila embryo as an excellent model for real time studies of apoptotic cell clearance.

Representative frames from a movie in which apoptotic cells are labeled with Annexin V, and glia, ectoderm and macrophages are labeled with simu-cytGFP are shown in Figure 2. Each frame is a projection of 3 slices 2 &mu;m each.
The embryo of stage 15 is properly positioned showing the embryonic CNS in the middle with well labeled glia (g). Macrophages (m), which are mostly outside the CNS, show strong cytoplasmic GFP expression. Ectodermal cells are also labeled...

Watch this Scientific Journal Video about Live Imaging of Apoptotic Cell Clearance during Drosophila Embryogenesis at JoVE.com

Live Imaging of Apoptotic Cell Clearance during Drosophila Embryogenesis

Here we describe an effective method for studying dynamics of apoptotic cell clearance in vivo. This method employs live Drosophila embryos as a powerful model for monitoring phagocytosis of apoptotic cells using specific labeling of apoptotic cells and phagocytes.

Live Imaging of Apoptotic Cell Clearance during Drosophila Embryogenesis

The  proper elimination of unwanted or aberrant cells through apoptosis and  subsequent phagocytosis (apoptotic cell clearance) is crucial for normal  ...

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13.4K Views.  Technion-Israel Institute of Technology. Qui si descrive un metodo efficace per lo studio delle dinamiche di gioco cellulare per apoptosi In vivo. Questo metodo impiega vivere Drosophila Embrioni come un potente modello per il monitoraggio fagocitosi delle cellule apoptotiche mediante etichettatura specifica delle cellule apoptotiche e fagociti.