This study was supported by the Astellas Foundation for Research on Metabolic Disorders (HT), Takeda Science Foundation (HT), and MEXT-Supported Program for the Strategic Research Foundation at Private Universities (HT).

NOTE: The transgenic flies used in this study include the following: DE-cad::GFP 10.
1. Preparation of Apple Plate
<ol>
	<li>Prepare a mixture of 12.5 g agar, 125 mL 100% commercially available apple juice, 12.5 g glucose, and 375 mL H2O. Heat the mixture in a microwave and pour it into a 3 cm cell culture dish. Store the mixture at 4 &#176;C for future use.</li>
	<li>After preparing the apple plate, add a thin layer of kneaded yeast paste on top of it to allow the flies to lay egg.</li>
</ol>
2. Embryo Preparation and Live Imaging Protocol
<ol>
	<li>Place approximately 50 flies (25 males and 25 females) in a bottle to mate and subsequently lay eggs overnight on an apple plate covered in kneaded yeast. Set the apple juice plate at the mouth of the bottle. Keep the bottle upside down in an incubator. Wrap the plastic Drosophila stock bottles with aluminum foil to prompt the flies to lay more eggs.</li>
	<li>The next morning, replace the old apple juice plate with a new one.</li>
	<li>Let the flies lay eggs for 3 to 4 h by wrapping the bottle with aluminum foil.</li>
	<li>Three to four hours later, collect the embryos in an embryo strainer from the apple juice plate using a brush or cotton bad and wash them with PBS. Wash the embryos 2 to 3 more times with PBS in 12-well culture dishes.</li>
	<li>Dechorionate the embryos with 50% bleach for 5 min in 12-well culture dishes.</li>
	<li>Following the dechorionation process, wash the embryos 2 to 3 more times with PBS.</li>
	<li>Transfer the embryos to a 3 cm cell culture dish containing PBS and select stage 5 embryos under the microscope based on the level of transparency at their borders. Pipette the staged embryos using a 200 &#181;L pipette tip.</li>
	<li>Next, place two selected embryos on a glass coverslip, and remove excess PBS with finely twisted tissue paper. Orient the embryos dorsal side up&#160;on the coverslip using a finely twisted tissue paper. After that, attach the embryos to the glass coverslip with silicon grease using a fine needle and twisted tissue paper.</li>
	<li>Add a small drop of halocarbon oil 700 on the embryos and place the coverslip containing the embryos upside down on the indented slide, leaving some space at the bottom of the slide.</li>
	<li>Examine the embryos using a confocal imaging system, an Argon/488 laser, and an oil-immersion objective (63X). 
	NOTE: Identifying the embryo at the appropriate developmental stage is important to capture images of the gastrulation event. Under these conditions, observe almost all embryos develop normally up to at least stage 14. The analyzed embryo can be cultured further to develop as an adult.</li>
</ol>

<ol>
	<li>Haruta, T., Warrior, R., Yonemura, S., Oda, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+proximal+half+of+the+Drosophila+E-cadherin+extracellular+region+is+dispensable+for+many+cadherin-dependent+events+but+required+for+ventral+furrow+formation.">The proximal half of the Drosophila E-cadherin extracellular region is dispensable for many cadherin-dependent events but required for ventral furrow formation.</a> Genes Cells. 15 (3), 193-208 (2010).</li><li>Oda, H., Takeichi, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Evolution:+structural+and+functional+diversity+of+cadherin+at+the+adherens+junction.">Evolution: structural and functional diversity of cadherin at the adherens junction.</a> J. Cell Biol. 193 (7), 1137-1146 (2011).</li><li>Fernandez-Sanchez, M. E., Serman, F., Ahmadi, P., Farge, E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mechanical+induction+in+embryonic+development+and+tumor+growth+integrative+cues+through+molecular+to+multicellular+interplay+and+evolutionary+perspectives.">Mechanical induction in embryonic development and tumor growth integrative cues through molecular to multicellular interplay and evolutionary perspectives.</a> Methods Cell Biol. 98, 295-321 (2010).</li><li>Alderton, G. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Metastasis:+Epithelial+to+mesenchymal+and+back+again.">Metastasis: Epithelial to mesenchymal and back again.</a> Nat. Rev. Cancer. 13 (1), 3 (2013).</li><li>Fabregat, I., Malfettone, A., Soukupova, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=New+Insights+into+the+Crossroads+between+EMT+and+Stemness+in+the+Context+of+Cancer.">New Insights into the Crossroads between EMT and Stemness in the Context of Cancer.</a> J. Clin. Med. 5 (3), (2016).</li><li>Serrano-Gomez, S. J., Maziveyi, M., Alahari, S. K. <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+epithelial-mesenchymal+transition+through+epigenetic+and+post-translational+modifications.">Regulation of epithelial-mesenchymal transition through epigenetic and post-translational modifications.</a> Mol. Cancer. 15, (2016).</li><li>Yu, A. Q., Ding, Y., Li, C. L., Yang, Y., Yan, S. R., Li, D. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=TALEN-induced+disruption+of+Nanog+expression+results+in+reduced+proliferation,+invasiveness+and+migration,+increased+chemosensitivity+and+reversal+of+EMT+in+HepG2+cells.">TALEN-induced disruption of Nanog expression results in reduced proliferation, invasiveness and migration, increased chemosensitivity and reversal of EMT in HepG2 cells.</a> Oncol. Rep. 35 (3), 1657-1663 (2016).</li><li>Zheng, X., 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=Epithelial-to-mesenchymal+transition+is+dispensable+for+metastasis+but+induces+chemoresistance+in+pancreatic+cancer.">Epithelial-to-mesenchymal transition is dispensable for metastasis but induces chemoresistance in pancreatic cancer.</a> Nature. 527 (7579), 525-530 (2015).</li><li>Kalluri, R., Weinberg, 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=The+basics+of+epithelial-mesenchymal+transition.">The basics of epithelial-mesenchymal transition.</a> J. Clin. Invest. 119 (6), 1420-1428 (2009).</li><li>Huang, J., Zhou, W., Dong, W., Watson, A. M., Hong, Y. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Directed,+efficient,+and+versatile+modifications+of+the+Drosophila+genome+by+genomic+engineering.">Directed, efficient, and versatile modifications of the Drosophila genome by genomic engineering.</a> Proc. Natl. Acad. Sci. U.S.A. 106 (20), 8284-8289 (2009).</li></ol>

The authors have nothing to disclose.

Although we have previously reported a similar procedure to capture live images of the gastrulation process in Drosophilla1, the method we describe here is detailed and easy to trace endogenous cadherin expression and thus is quite useful for genetic screening of key factors involved in gastrulation. To maximize success with this imaging procedure, it is essential to use an indented slide. Mechanical pressure sometimes causes embryonic death. Therefore, it is also important to handle the embryos as gently as possible since any mechanical stress could disrupt the process of embryonic gastrulation. Using the proper amount of grease during embryo fixation will further improve the results of the live imaging procedure. 
Ensuring that both the dechorionation and selection of the embryos are performed quickly is a key factor in achieving success with this protocol. Using a fine needle to glue the embryos before completely drying is also vital to maximizing results with this procedure. After fixing the embryo, GFP labeled DE-cadherin is examined with a confocal microscope. During live imaging experiments, images were taken every 10 s for less than 30 min1. Under these conditions, almost all embryos develop normally up to at least stage 14. The laser power should also be optimized. It is also important to perform the embryo treatment properly to reduce the potential autofluorescence from the vitelline membrane.
Gastrulation is a dynamic event that occurs during stage 6 of the developmental process. This stage of development is directly controlled by inherited genetic patterning. Using our established Drosophila gastrulation live imaging procedure with DE-cadherin GFP transgenic lines, we will be able to further understand the molecular mechanisms underlying Drosophila gastrulation as well as the epithelial-to-mesenchymal transition involved in cancer metastasis.

Gastrulation is the first set of morphologically dynamic events that occur during embryonic development of multicellular animals such as Drosophila1,2. Interestingly, emerging evidence suggests that this process is regulated through the interplay between mechanical and molecular mechanisms3. Moreover, the epithelial to mesenchymal transition (EMT), which is a crucial process in gastrulation, is also implicated in human disease processes such as cancer metastasis4-8. As such, many genes that control apical constriction are also known to be key factors in the EMT observed in cancer metastasis9. Thus, apical constriction at the time of gastrulation is an excellent model to investigate the aforementioned regulatory mechanisms and to enhance our understanding of cancer metastasis. The advantage of this technique is that we can observe cell movement at the time of gastrulation in real-time and therefore, we will be able to screen genes involved in gastrulation as well as cancer metastasis.
Although relatively unknown, cell-to-cell adhesion is thought to play a central role in apical constriction1. Drosophila genetics is well suited for single cell level investigations exploring regulatory molecular mechanisms. This model will enable us to uncover the importance of apical constriction during gastrulation. Moreover, this method can be used to screen genes involved in cancer metastasis. Capturing live images of Drosophila gastrulation has further enabled us to understand in greater detail the molecular mechanisms governing tissue rearrangement. Herein, we provide a comprehensive description of a simple method to achieve this.

<table><tbody><tr><td>Halocarbon oil 700</td><td>Sigma</td><td>MKBH 5726</td><td></td></tr><tr><td>Vacuum grease Silicone</td><td>Beckman</td><td>335148</td><td></td></tr><tr><td>Glass coverslip&amp;nbsp;</td><td>Matsunami glass</td><td>Thickness No1</td><td>24 - 36 mm</td></tr><tr><td>Embryo stariner</td><td>Corning</td><td>Corning3477</td><td></td></tr><tr><td>Plastic Drosophilla Stock Bottles</td><td>Hitec</td><td>MKC-100</td><td></td></tr><tr><td>DE-Cadherin knock-in flies</td><td></td><td></td><td>REF (10)</td></tr></tbody></table>

imaging of cell shape alteration and cell movement in drosophila gastrulation using de-cadherin reporter transgenic flies

Gastrulation is the first set of morphologically dynamic events that occur during the embryonic development of multicellular animals such as Drosophila. This morphological alteration is also recognized as epithelial to mesenchymal transition (EMT). Dysregulation of EMT is associated with fibrosis and cancer metastasis. There is emerging evidence that EMT is controlled by a number of molecular mechanisms. As such, many key genes that control apical constriction are also known to be important factors in the EMT observed in cancer metastasis. Like EMT during Drosophila gastrulation, epithelial cells can be induced to change their shape and be reprogrammed to redirect cell fate towards various other cell types. Here we provide a robust imaging method of Drosophila gastrulation to assay the initiation of morphogenetic cellular movements and cell fate identification during this stage of embryonic development. Using this method, we identify cell rearrangement at the time of gastrulation and demonstrate the importance of apical constriction during gastrulation using GFP labeled DE-cadherin.

Here, we show the gastrulation events of the Drosophila embryo and a general overview of the embryo preparation procedure (Figure 1). Cell membranes are labeled using DE-cadherin::GFP and live imaging of cell movements is performed at the time of gastrulation in Drosophila (Figure 2). Since DE-cadherin GFP flies allow us to visualize cell adherence junctions, we are able to trace apical cell shape and movements using this system. More importantly, this system also allows us to trace endogenous DE-cadherin expression patterns.
<img alt="Figure 1" src="/files/ftp_upload/54764/54764fig1.jpg" /> 
Figure 1: General Overview of the Embryo Preparation Procedure. A) Set up flies for egg laying. B) Collect embryos and place them in an embryo strainer. C) After washing the embryos with PBS, dechorionate them immediately. D) Transfer the embryos to a 3 cm cell culture dish using PBS. E) Pipet the embryos that are at the correct developmental stage and place them on a coverslip. F) Attach the embryos to the coverslip using vacuum grease. G) Next add a drop of halocarbon oil onto the coverslip. H) Finally place the coverslip upside down on the indented slide. The embryos are now ready for time-lapse imaging. <a href="https://cloudflare-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/54764/54764fig1large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<img alt="Figure 2" src="/files/ftp_upload/54764/54764fig2.jpg" /> 
Figure 2: The Result of an Experimental Procedure utilizing DE-cad::GFP-based Live Imaging During Gastrulation. Cell membranes were labeled using DE-cadherin::GFP and live imaging of cell movement was then captured for approximately 500 s during gastrulation of Drosophila. Apical cell perimeters were visualized using the GFP fluorescence of DE-Cad in order to trace the apical areas of individual cells using a representative set of time-lapse images; Scale bar = 20 &#181;m. The arrowheads show where apical constriction and invagination occur. <a href="https://cloudflare-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/54764/54764fig2large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>

Watch this Scientific Journal Video about Imaging of Cell Shape Alteration and Cell Movement in Drosophila Gastrulation Using DE-cadherin Reporter Transgenic Flies at JoVE.com

Imaging of Cell Shape Alteration and Cell Movement in Drosophila Gastrulation Using DE-cadherin Reporter Transgenic Flies

Herein we describe a procedure to capture live images of Drosophila gastrulation. This has enabled us to better understand the apical constriction involved in early development and further analyze mechanisms governing cellular movements during tissue structure modification.

Imaging of Cell Shape Alteration and Cell Movement in Drosophila Gastrulation Using DE-cadherin Reporter Transgenic Flies

Gastrulation is the first set of morphologically dynamic events that occur during the embryonic development of multicellular animals such as Drosophila. ...

imaging-cell-shape-alteration-cell-movement-drosophila-gastrulation

Nanyang Technological University

Research

JoVE Journal

Developmental Biology

7.0K Views.  Jahangirnagar University. Herein we describe a procedure to capture live images of Drosophila gastrulation. This has enabled us to better understand the apical constriction involved in early development and further analyze mechanisms governing cellular movements during tissue structure modification.

Video: Imaging of Cell Shape Alteration and Cell Movement in Drosophila Gastrulation Using DE-cadherin Reporter Transgenic Flies

Live-imaging of the Drosophila Pupal Eye

Inherent processes of Drosophila pupal development can shift and distort the eye epithelium in ways that make individual cell behavior difficult to track during live cell imaging. These processes include: retinal rotation, cell growth and organismal movement. Additionally, irregularities in the topology of the epithelium, including subtle bumps and folds often introduced as the pupa is prepared for imaging, make it challenging to acquire in-focus images of more than a few ommatidia in a single focal plane. The workflow outlined here remedies these issues, allowing easy analysis of cellular processes during Drosophila pupal eye development. Appropriately-staged pupae are arranged in an imaging rig that can be easily assembled in most laboratories. Ubiquitin-DE-Cadherin:GFP and GMR-GAL4&#8211;driven UAS-&#945;-catenin:GFP are used to visualize cell boundaries in the eye epithelium 1-3. After deconvolution is applied to fluorescent images captured at multiple focal planes, maximum projection images are generated for each time point and enhanced using image editing software. Alignment algorithms are used to quickly stabilize superfluous motion, making individual cell behavior easier to track.

Live-imaging of the Drosophila Pupal Eye

This protocol presents an efficient method for imaging the live Drosophila pupal eye neuroepithelium. This method compensates for tissue movement and uneven topology, enhances visualization of cell boundaries through the use of multiple GFP-tagged junction proteins, and uses an easily-assembled imaging rig.

Inherent processes of Drosophila pupal development can shift and distort the eye epithelium in ways that make individual cell behavior difficult to track ...

The Drosophila Imaginal Disc Tumor Model: Visualization and Quantification of Gene Expression and Tumor Invasiveness Using Genetic Mosaics

Drosophila melanogaster has emerged as a powerful experimental system for functional and mechanistic studies of tumor development and progression in the context of a whole organism. Sophisticated techniques to generate genetic mosaics facilitate induction of visually marked, genetically defined clones surrounded by normal tissue. The clones can be analyzed through diverse molecular, cellular and omics approaches. This study describes how to generate fluorescently labeled clonal tumors of varying malignancy in the eye/antennal imaginal discs (EAD) of Drosophila larvae using the Mosaic Analysis with a Repressible Cell Marker (MARCM) technique. It describes procedures how to recover the mosaic EAD and brain from the larvae and how to process them for simultaneous imaging of fluorescent transgenic reporters and antibody staining. To facilitate molecular characterization of the mosaic tissue, we describe a protocol for isolation of total RNA from the EAD. The dissection procedure is suitable to recover EAD and brains from any larval stage. The fixation and staining protocol for imaginal discs works with a number of transgenic reporters and antibodies that recognize Drosophila proteins. The protocol for RNA isolation can be applied to various larval organs, whole larvae, and adult flies. Total RNA can be used for profiling of gene expression changes using candidate or genome-wide approaches. Finally, we detail a method for quantifying invasiveness of the clonal tumors. Although this method has limited use, its underlying concept is broadly applicable to other quantitative studies where cognitive bias must be avoided.

The Drosophila Imaginal Disc Tumor Model: Visualization and Quantification of Gene Expression and Tumor Invasiveness Using Genetic Mosaics

This protocol demonstrates how to generate fluorescently marked, genetically defined clonal tumors in the Drosophila eye/antennal imaginal discs (EAD). It describes how to dissect the EAD and brain from the third instar larvae and how to process them to visualize and quantify gene expression changes and tumor invasiveness.

Drosophila melanogaster has emerged as a powerful experimental system for functional and mechanistic studies of tumor development and progression in the ...

Cancer Research

Upright Imaging of Drosophila Egg Chambers

Drosophila melanogaster oogenesis provides an ideal context for studying varied developmental processes since the ovary is relatively simple in architecture, is well-characterized, and is amenable to genetic analysis. Each egg chamber consists of germ-line cells surrounded by a single epithelial layer of somatic follicle cells. Subsets of follicle cells undergo differentiation during specific stages to become several different cell types. Standard techniques primarily allow for a lateral view of egg chambers, and therefore a limited view of follicle cell organization and identity. The upright imaging protocol describes a mounting technique that enables a novel, vertical view of egg chambers with a standard confocal microscope. Samples are first mounted between two layers of glycerin jelly in a lateral (horizontal) position on a glass microscope slide. The jelly with encased egg chambers is then cut into blocks, transferred to a coverslip, and flipped to position egg chambers upright. Mounted egg chambers can be imaged on either an upright or an inverted confocal microscope. This technique enables the study of follicle cell specification, organization, molecular markers, and egg development with new detail and from a new perspective.

Upright Imaging of Drosophila Egg Chambers

The upright imaging method described in this protocol allows for the detailed visualization of the poles of a developing Drosophila melanogaster egg. This end-on view provides a new perspective into the arrangements and morphologies of multiple cell types in the follicular epithelium.

Drosophila melanogaster oogenesis provides an ideal context for studying varied developmental processes since the ovary is relatively simple in ...

Using Microfluidics Chips for Live Imaging and Study of Injury Responses in Drosophila Larvae

Live imaging is an important technique for studying cell biological processes, however this can be challenging in live animals. The translucent cuticle of the Drosophila larva makes it an attractive model organism for live imaging studies. However, an important challenge for live imaging techniques is to noninvasively immobilize and position an animal on the microscope. This protocol presents a simple and easy to use method for immobilizing and imaging Drosophila larvae on a polydimethylsiloxane (PDMS) microfluidic device, which we call the 'larva chip'. The larva chip is comprised of a snug-fitting PDMS microchamber that is attached to a thin glass coverslip, which, upon application of a vacuum via a syringe, immobilizes the animal and brings ventral structures such as the nerve cord, segmental nerves, and body wall muscles, within close proximity to the coverslip. This allows for high-resolution imaging, and importantly, avoids the use of anesthetics and chemicals, which facilitates the study of a broad range of physiological processes. Since larvae recover easily from the immobilization, they can be readily subjected to multiple imaging sessions. This allows for longitudinal studies over time courses ranging from hours to days. This protocol describes step-by-step how to prepare the chip and how to utilize the chip for live imaging of neuronal events in 3rd instar larvae. These events include the rapid transport of organelles in axons, calcium responses to injury, and time-lapse studies of the trafficking of photo-convertible proteins over long distances and time scales. Another application of the chip is to study regenerative and degenerative responses to axonal injury, so the second part of this protocol describes a new and simple procedure for injuring axons within peripheral nerves by a segmental nerve crush.

Using Microfluidics Chips for Live Imaging and Study of Injury Responses in Drosophila Larvae

Drosophila larvae are an attractive model system for live imaging due to their translucent cuticle and powerful genetics. This protocol describes how to utilize a single-layer PDMS device, called the &#39;larva chip&#39; for live imaging of cellular processes within neurons of 3rd instar Drosophila larvae.

Live imaging is an important technique for studying cell biological processes, however this can be challenging in live animals. The translucent cuticle of ...

Bioengineering

Live Imaging of Glial Cell Migration in the Drosophila Eye Imaginal Disc

Glial cells of both vertebrate and invertebrate organisms must migrate to final target regions in order to ensheath and support associated neurons. While recent progress has been made to describe the live migration of glial cells in the developing pupal wing (1), studies of Drosophila glial cell migration have typically involved the examination of fixed tissue. Live microscopic analysis of motile cells offers the ability to examine cellular behavior throughout the migratory process, including determining the rate of and changes in direction of growth. Paired with use of genetic tools, live imaging can be used to determine more precise roles for specific genes in the process of development. Previous work by Silies et al. (2) has described the migration of glia originating from the optic stalk, a structure that connects the developing eye and brain, into the eye imaginal disc in fixed tissue. Here we outline a protocol for examining the live migration of glial cells into the Drosophila eye imaginal disc. We take advantage of a Drosophila line that expresses GFP in developing glia to follow glial cell progression in wild type and in mutant animals.

Here we describe a protocol to examine the migration of glial cells into the developing Drosophila eye using live microscopic analysis paired with GFP tagged glial cells.

Glial cells of both vertebrate and invertebrate organisms must migrate to final target regions in order to ensheath and support associated neurons.  While ...

Biology

A Cell-based Assay to Investigate Non-muscle Myosin II Contractility via the Folded-gastrulation Signaling Pathway in Drosophila S2R+ Cells

We have developed a cell-based assay using Drosophila cells that recapitulates apical constriction initiated by folded gastrulation (Fog), a secreted epithelial morphogen. In this assay, Fog is used as an agonist to activate Rho through a signaling cascade that includes a G-protein-coupled receptor (Mist), a G&#945;12/13 protein (Concertina/Cta), and a PDZ-domain-containing guanine nucleotide exchange factor (RhoGEF2). Fog signaling results in the rapid and dramatic reorganization of the actin cytoskeleton to form a contractile purse string. Soluble Fog is collected from a stable cell line and applied ectopically to S2R+ cells, leading to morphological changes like apical constriction, a process observed during developmental processes such as gastrulation. This assay is amenable to high-throughput screening and, using RNAi, can facilitate the identification of additional genes involved in this pathway.

A Cell-based Assay to Investigate Non-muscle Myosin II Contractility via the Folded-gastrulation Signaling Pathway in Drosophila S2R+ Cells

Here we describe a contractility assay using Drosophila S2R+ cells. The application of an exogenous ligand, folded gastrulation (Fog), leads to the activation of the Fog signaling pathway and cellular contractility. This assay can be used to investigate the regulation of cellular contractility proteins in the Fog signaling pathway.

We have developed a cell-based assay using Drosophila cells that recapitulates apical constriction initiated by folded gastrulation (Fog), a secreted ...

Live Imaging Of Drosophila melanogaster Embryonic Hemocyte Migrations

Many studies address cell migration using in vitro methods, whereas the physiologically relevant environment is that of the organism itself. Here we present a protocol for the mounting of Drosophila melanogaster embryos and subsequent live imaging of fluorescently labeled hemocytes, the embryonic macrophages of this organism. Using the Gal4-uas system1 we drive the expression of a variety of genetically encoded, fluorescently tagged markers in hemocytes to follow their developmental dispersal throughout the embryo. Following collection of embryos at the desired stage of development, the outer chorion is removed and the embryos are then mounted in halocarbon oil between a hydrophobic, gas-permeable membrane and a glass coverslip for live imaging. In addition to gross migratory parameters such as speed and directionality, higher resolution imaging coupled with the use of fluorescent reporters of F-actin and microtubules can provide more detailed information concerning the dynamics of these cytoskeletal components.

Live Imaging Of Drosophila melanogaster Embryonic Hemocyte Migrations

Drosophila hemocytes disperse over the entirety of the developing embryo. This protocol demonstrates how to mount and image these migrations using embryos with fluorescently labelled hemocytes.

Many studies address cell migration using in vitro methods, whereas the physiologically relevant environment is that of the organism itself. Here we ...

Imaging and Analysis of Tissue Orientation and Growth Dynamics in the Developing Drosophila Epithelia During Pupal Stages

Within multicellular organisms, mature tissues and organs display high degrees of order in the spatial arrangements of their constituent cells. A remarkable example is given by sensory epithelia, where cells of the same or distinct identities are brought together via cell-cell adhesion showing highly organized planar patterns. Cells align to one another in the same direction and display equivalent polarity over large distances. This organization of the mature epithelia is established over the course of morphogenesis. To understand how the planar arrangement of the mature epithelia is achieved, it is crucial to track cell orientation and growth dynamics with high spatiotemporal fidelity during development in vivo. Robust analytical tools are also essential to identify and characterize local-to-global transitions. The Drosophila pupa is an ideal system to evaluate oriented cell shape changes underlying epithelial morphogenesis. The pupal developing epithelium constitutes the external surface of the immobile body, allowing long-term imaging of intact animals. The protocol described here is designed to image and analyze cell behaviors at both global and local levels in the pupal abdominal epidermis as it grows. The methodology described can be easily adapted to the imaging of cell behaviors at other developmental stages, tissues, subcellular structures, or model organisms.

Imaging and Analysis of Tissue Orientation and Growth Dynamics in the Developing Drosophila Epithelia During Pupal Stages

This protocol is designed for the imaging and analysis of the dynamics of cell orientation and tissue growth in the Drosophila abdominal epithelia as the fruit fly undergoes metamorphosis. The methodology described here can be applied to the study of different developmental stages, tissues, and subcellular structures in Drosophila or other model organisms.

Within multicellular organisms, mature tissues and organs display high degrees of order in the spatial arrangements of their constituent cells. A ...

Imaging Cell Shape Change in Living Drosophila Embryos

The developing Drosophila melanogaster embryo undergoes a number of cell shape changes that are highly amenable to live confocal imaging. Cell shape changes in the fly are analogous to those in higher organisms, and they drive tissue morphogenesis. So, in many cases, their study has direct implications for understanding human disease (Table 1)1-5. On the sub-cellular scale, these cell shape changes are the product of activities ranging from gene expression to signal transduction, cell polarity, cytoskeletal remodeling and membrane trafficking. Thus, the Drosophila embryo provides not only the context to evaluate cell shape changes as they relate to tissue morphogenesis, but also offers a completely physiological environment to study the sub-cellular activities that shape cells.
The protocol described here is designed to image a specific cell shape change called cellularization. Cellularization is a process of dramatic plasma membrane growth, and it ultimately converts the syncytial embryo into the cellular blastoderm. That is, at interphase of mitotic cycle 14, the plasma membrane simultaneously invaginates around each of ~6000 cortically anchored nuclei to generate a sheet of primary epithelial cells. Counter to previous suggestions, cellularization is not driven by Myosin-2 contractility6, but is instead fueled largely by exocytosis of membrane from internal stores7. Thus, cellularization is an excellent system for studying membrane trafficking during cell shape changes that require plasma membrane invagination or expansion, such as cytokinesis or transverse-tubule (T-tubule) morphogenesis in muscle.
Note that this protocol is easily applied to the imaging of other cell shape changes in the fly embryo, and only requires slight adaptations such as changing the stage of embryo collection, or using "embryo glue" to mount the embryo in a specific orientation (Table 1)8-19. In all cases, the workflow is basically the same (Figure 1). Standard methods for cloning and Drosophila transgenesis are used to prepare stable fly stocks that express a protein of interest, fused to Green Fluorescent Protein (GFP) or its variants, and these flies provide a renewable source of embryos. Alternatively, fluorescent proteins/probes are directly introduced into fly embryos via straightforward micro-injection techniques9-10. Then, depending on the developmental event and cell shape change to be imaged, embryos are collected and staged by morphology on a dissecting microscope, and finally positioned and mounted for time-lapse imaging on a confocal microscope.

Imaging Cell Shape Change in Living Drosophila Embryos

Early development of the fruit fly, Drosophila melanogaster, is characterized by a number of cell shape changes that are well suited for imaging approaches. This article will describe basic tools and methods required for live confocal imaging of Drosophila embryos, and will focus on a cell shape change called cellularization.

The developing Drosophila melanogaster embryo undergoes a number of cell shape changes that are highly amenable to live confocal imaging.  Cell shape ...

Extended Live Imaging of Drosophila Pupal Leg Morphogenesis Without Puparium

Long-Term Live Imaging of Drosophila Pupal Leg Development After Puparium Removal

Over the past decades, significant progress has been made in understanding the mechanisms of cell fate determination. However, the process by which fate-determined cells form three-dimensional organismal shapes remains unclear. Recent advances in confocal microscopy have facilitated efforts to observe cell dynamics during development through live imaging. The Drosophila melanogaster pupa is ideal for live imaging due to its immobility, transparent pupal cuticle, and the availability of fluorescent reporter lines. A primary challenge for imaging is the puparium, the cuticle surrounding the pupa, which obstructs optical imaging. While previous methods involved either partial or complete removal of the puparium, maintaining pupal viability for extended periods after this procedure has remained challenging. Here, a simple method is presented for days-long live imaging of the Drosophila leg during the pupal stage, involving complete puparium removal. The method includes removing the puparium from a pupa adhered to double-sided tape, followed by assembling a small chamber on a glass-bottom dish to enclose the pupa and a drop of water. This setup is straightforward, reliable, and supports extended pupal survival by preventing desiccation. Long-term live imaging of the Drosophila pupa has significantly contributed to capturing how the adult leg undergoes dramatic three-dimensional structural changes over 2-3 days. These changes include the transient formation of an intriguing structure (the Parthenon-like structure) by epithelial cells, rapid tissue narrowing, joint formation, and bristle elongation. This method is applicable to the observation of various tissues and can potentially be combined with other techniques, such as optical gene induction, to advance the understanding of cell dynamics during the final shape formation of tissues in the pupal stage.

Long-Term Live Imaging of Drosophila Pupal Leg Development After Puparium Removal

Here, a protocol is presented for long-term live imaging of the Drosophila leg during the pupal stage, involving complete removal of the puparium. This protocol can also be applied to other tissues.

Over the past decades, significant progress has been made in understanding the mechanisms of cell fate determination. However, the process by which ...

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