We would like to convey our appreciation for the input and comments from members of the Padilla Lab. Nematode strains in this work were provided by the Caenorhabditis Genetics Center, which is funded by the NIH National Center for Research Resources (NCRR). We acknowledge and thank Dr. Lon Turnbull for technical assistance with confocal microscopy. This work has been supported by a grant from the National Science Foundation (NSF-IOS, CAREER) to P.A.P.

1. Sample Preparation
<ol>
	<li>Produce or obtain appropriate transgenic C. elegans strain of interest using transgenic methodologies or from Caenorhabditis Genetics Stock Center (CGC) or colleague. In this case we are using strain TH32 (pie-1::tbg-1::GFP; pie-1::GFP::H2B)5 to visualize chromosomes and centrosomes as markers for cell division.</li>
	<li>Generate a synchronized population by using one of three methods: 1) disintegrate gravid adults in hypochlorite solution and use remaining embryos6, 2) pick gravid adults onto a seeded plate and let them lay embryos for 1-2 hr, or 3) pick L4 larvae from a mixed population and move to a new seeded plate.</li>
	<li>Grow nematodes at 20 &deg;C to gravid young adulthood, which will take approximately 96 hr from hatching, 72 hr from L1 larvae or 24 hr post L4 molt. Embryos (2-20 cell) in utero contain large blastomeres and nuclei that are optimal for imaging sub-cellular and sub-nuclear changes, respectively. This methodology provides a means to generate a population of young adults that contain an abundant number of early embryos.</li>
</ol>
2. Slide Preparation and Anoxia Chamber Set Up
<ol>
	<li>Make a humid chamber to hold prepared slides by placing a damp paper towel inside a large Petri dish or bin covered with a lid of sufficient size.</li>
	<li>Prepare molten 2% agarose in deionized H2O by heating mixture in glassware via microwave or water bath.</li>
	<li>Place 1-3 drops of warm agarose on a clean glass microscope slide. Immediately place a second slide inverted perpendicularly on top of the agarose drop(s), press slightly so that the resulting pad will be thin and free of air bubbles.</li>
	<li>Allow time to cool and slowly take apart the two microscope slides leaving the agarose pad intact on one of the slides. It is important to ensure the agarose pad is thin enough to not interfere with the ability to focus the microscope later. Ability to visualize sample is also dependent upon the specific optical distance of the objective in use, which can vary between microscopes.</li>
	<li>Use a clean razor blade to shape agarose pad into a small square. Store in the prepared humid chamber until ready to use.</li>
	<li>Carefully, using the same clean razor blade, take the edge of the agarose pad and transfer it from the slide onto a round 25 mm micro coverglass, avoiding the accumulation of air bubbles underneath the pad. The round coverglass selected to use fits appropriately in the microincubator.</li>
	<li>Add a drop of anesthetic (0.5% tricaine, 0.05% tetramisole in M9 buffer) onto the agarose pad for use as an anesthetic. Pick 5-10 worms and place into the drop of anesthetic. Allow 1-3 min for worms to cease movement.</li>
	<li>The rationale for observing embryos within the adult uterus, instead of dissected embryos, is to minimize the potential of embryo desiccation and movement due to the flow of nitrogen gas across the embryo.</li>
	<li>Immediately add a drop of halocarbon oil on top of the worms to prevent the worms from dehydration as gas is flowed through the chamber. Since the halocarbon oil is viscous one may use a pipet tip or tip of a worm pick to collect oil and drop onto the worms.</li>
	<li>Once the circular coverglass containing the worms is ready, the two halves of the Leiden closed perfusion microincubator are separated, and the coverglass is then carefully placed upright onto the bottom ring. The two sides of the chamber are then closed tightly together.</li>
	<li>The chamber is then connected to the nitrogen gas tank via flexible plastic tubing and placed into the appropriate spot on the microscope stage (Figure 1C). At this time the tubing and microincubator should be carefully checked for any leaks by ensuring secure attachment of the tubing and of the port plugs along the side of the chamber. One can also lightly spread a small amount of soap water over the tubing to look for bubbles, which will form if a leak is present.</li>
</ol>
3. Microscopy in Anoxia
<ol>
	<li>Locate animals at lower magnification, then, move to the appropriate higher magnification (64x for this application) to image tissue or cells of interest such as embryonic blastomeres or oocytes in adults. Turn on the 488 nm laser to view GFP signal and locate GFP fusion protein in the cell(s) of interest.</li>
	<li>To visualize the arrest at specific stage of cell cycle arrest (e.g. late prophase) identify a blastomere at a prior stage of cell division (e.g. late interphase or early prophase). Cellular markers such as centriole position, initiation of chromosome condensation, chromosome location and presence or absence of the nuclear envelope will help identify cell cycle stage (Figure 2A).</li>
	<li>The chamber is then perfused with nitrogen gas (99.999% N2; &lt;2 ppm O2). In this case we use a pressure of 6 psi, however pressure may need to be adjusted and optimized depending on size of each microincubator and diameter of tubing in use. Continue to monitor the blastomere(s) as the nitrogen fills the chamber, adjusting the focal plane as necessary.</li>
	<li>At this point, time-lapse imaging has begun. Imaging is conducted for as long as necessary to capture phenomenon of interest, in this case prophase arrest and docking of chromosomes to the inner nuclear membrane. Images are taken once every 10 sec for no longer than 30 min. Frequencies of image capture and settings such as gain and laser power should be adjusted as necessary.</li>
	<li>The time in which the embryos respond to the anoxic environment can vary depending on cell cycle stage upon anoxia exposure. Typically anoxia-induced prophase arrest occurs within 20-30 min of beginning nitrogen gas flow. We have observed anoxia-induced cell cycle arrest occurring in &lt;20 min. Images can be obtained during this time frame, or specific images can be isolated later from a time-lapse series. An additional option is to use video microscopy to visualize sub-cellular structures in embryos.</li>
	<li>To document recovery from the anoxia-induced arrested state, the gas is turned off and the chamber is allowed to return to normoxia by diffusion while recording a time-lapse series. Resumption of cell cycle progression and undocking of chromosomes typically occurs within 5-20 min of turning the nitrogen gas off.</li>
	<li>Note that in separate experiments an anoxia indicator, resazurin, was placed in the flow-through microchamber; it was determined that the chamber becomes anoxic on average of approximately 19 min after nitrogen gas flow has started.</li>
	<li>Images and videos are processed using Imaris, Image J or Photoshop and imported into QuickTime for display.</li>
</ol>

<ol>
	<li>Powell-Coffman, J. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Hypoxia+signaling+and+resistance+in+C.+elegans.">Hypoxia signaling and resistance in C. elegans.</a> Trends Endocrinol. Metab. 21 (10), 435-440 (2010).</li><li>Padilla, P. A., Ladage, M. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Suspended+animation,+diapause+and+quiescence:+Arresting+the+cell+cycle+in+C.+elegans.">Suspended animation, diapause and quiescence: Arresting the cell cycle in C. elegans.</a> Cell Cycle. 11, (2012).</li><li>Hu, P. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Dauer.">Dauer.</a> WormBook. , 1-19 (2007).</li><li>Zhou, K. I., Pincus, Z., Slack, F. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Longevity+and+stress+in+Caenorhabditis+elegans.">Longevity and stress in Caenorhabditis elegans.</a> Aging (Albany NY). 3, 733-753 (2011).</li><li>Schmidt, D. J., Rose, D. J., Saxton, W. M., Strome, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Functional+analysis+of+cytoplasmic+dynein+heavy+chain+in+Caenorhabditis+elegans+with+fast-acting+temperature-sensitive+mutations.">Functional analysis of cytoplasmic dynein heavy chain in Caenorhabditis elegans with fast-acting temperature-sensitive mutations.</a> Mol. Biol. Cell. 16, 1200-1212 (2005).</li><li>Sulston, J., Hodgkin, J., Wood, W. B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> The Nematode Caenorhabditis elegans. , 587-606 (1988).</li><li>Padilla, P. A., Nystul, T. G., Zager, R. A., Johnson, A. C., Roth, M. B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Dephosphorylation+of+Cell+Cycle-regulated+Proteins+Correlates+with+Anoxia-induced+Suspended+Animation+in+Caenorhabditis+elegans.">Dephosphorylation of Cell Cycle-regulated Proteins Correlates with Anoxia-induced Suspended Animation in Caenorhabditis elegans.</a> Mol. Biol Cell. 13, 1473-1483 (2002).</li><li>Hajeri, V. A., Trejo, J., Padilla, P. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Characterization+of+sub-nuclear+changes+in+Caenorhabditis+elegans+embryos+exposed+to+brief,+intermediate+and+long-term+anoxia+to+analyze+anoxia-induced+cell+cycle+arrest.">Characterization of sub-nuclear changes in Caenorhabditis elegans embryos exposed to brief, intermediate and long-term anoxia to analyze anoxia-induced cell cycle arrest.</a> BMC Cell Biol. 6, 1471-2121 (2005).</li><li>Padilla, P. A., Goy, J. M., Hajeri, P. A., Padilla, <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Anoxia. , (2012).</li><li>Hajeri, V. A., Little, B. A., Ladage, M. L., Padilla, P. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=NPP-16/Nup50+function+and+CDK-1+inactivation+are+associated+with+anoxia-induced+prophase+arrest+in+Caenorhabditis+elegans.">NPP-16/Nup50 function and CDK-1 inactivation are associated with anoxia-induced prophase arrest in Caenorhabditis elegans.</a> Mol. Biol. Cell. 21, 712-724 (2010).</li><li>Nystul, T. G., Goldmark, J. P., Padilla, P. A., Roth, M. B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Suspended+animation+in+C.+elegans+requires+the+spindle+checkpoint.">Suspended animation in C. elegans requires the spindle checkpoint.</a> Science. 302, 1038-1041 (2003).</li><li>Margalit, A., Vlcek, S., Gruenbaum, Y., Foisner, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Breaking+and+making+of+the+nuclear+envelope.">Breaking and making of the nuclear envelope.</a> J. Cell Biochem. 95, 454-465 (2005).</li><li>Maddox, A. S., Maddox, P. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=High-resolution+imaging+of+cellular+processes+in+Caenorhabditis+elegans.">High-resolution imaging of cellular processes in Caenorhabditis elegans.</a> Methods Cell Biol. 107, 1-34 (2012).</li><li>Miller, D. L., Roth, M. B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=C.+elegans+are+protected+from+lethal+hypoxia+by+an+embryonic+diapause.">C. elegans are protected from lethal hypoxia by an embryonic diapause.</a> Curr. Biol. 19, 1233-1237 (2009).</li></ol>

No conflicts of interest declared.

Oxygen Deprivation and Suspended Animation
Although exposure to severe oxygen deprivation can be fatal for some organisms, some organisms are able to survive exposure to anoxia. In the case of C. elegans, survival of anoxia exposure depends on developmental stage and response to anoxia is entry into a reversible state of suspended animation in which a number of observable biological processes are arrested. Cell division, development, movement, eating and reproductive processes cease unt...

<table border="1">
	<tbody>
		<tr>
			<td>Reagents/Equipment</td>
			<td></td>
			<td></td>
			<td>Composition</td>
		</tr>
		<tr>
			<td>Hypochlorite solution</td>
			<td>&nbsp;</td>
			<td>&nbsp;</td>
			<td>0.7 g KOH, 12 ml 5% NaOCl, bring to 50 ml with ddH20</td>
		</tr>
		<tr>
			<td>M9 buffer</td>
			<td>&nbsp;</td>
			<td>&nbsp;</td>
			<td>3 g KH2PO4, 11 g Na2HPO4, 5 g NaCl, 1 ml (1 M) MgSO4 per 1 L ddH2O</td>
		</tr>
		<tr>
			<td>Glass microscope slides</td>
			<td>Fisher Scientific</td>
			<td>12-550-343</td>
			<td>3"x1"x1.0 mm</td>
		</tr>
		<tr>
			<td>Round micro coverglass</td>
			<td>Electron Microscopy Sciences</td>
			<td>72223-01</td>
			<td>25 mm Diameter</td>
		</tr>
		<tr>
			<td>Halocarbon oil 700</td>
			<td>Sigma</td>
			<td>H8898-100ml</td>
			<td>&nbsp;</td>
		</tr>
		<tr>
			<td>Anesthetic</td>
			<td>&nbsp;</td>
			<td>&nbsp;</td>
			<td>0.5% tricaine, 0.05% tetramisole</td>
		</tr>
		<tr>
			<td>Leiden Closed Perfusion Microincubator</td>
			<td>Harvard Apparatus</td>
			<td>650041</td>
			<td>&nbsp;</td>
		</tr>
		<tr>
			<td>UHP Nitrogen</td>
			<td>Calgaz (Air Liquide)</td>
			<td>&nbsp;</td>
			<td>&gt;99.9990% N2 &lt;2 ppm O2</td>
		</tr>
		<tr>
			<td>Plastic tubing</td>
			<td>VWR</td>
			<td>89068-468</td>
			<td>0.062" ID x 0.125" OD</td>
		</tr>
		<tr>
			<td>Spinning Disk Confocal Microscope</td>
			<td>McBain Systems</td>
			<td>&nbsp;</td>
			<td>Zeiss inverted optical microscope, epifluorescence illumination system, CSU-10 Yokogawa confocal scanner, Hamamatsu electron multiplier CCD camera.</td>
		</tr>
	</tbody>
</table>

use of time lapse microscopy to visualize anoxia-induced suspended animation in c. elegans embryos

Caenorhabdits elegans has been used extensively in the study of stress resistance, which is facilitated by the transparency of the adult and embryo stages as well as by the availability of genetic mutants and transgenic strains expressing a myriad of fusion proteins1-4. In addition, dynamic processes such as cell division can be viewed using fluorescently labeled reporter proteins. The study of mitosis can be facilitated through the use of time-lapse experiments in various systems including intact organisms; thus the early C. elegans embryo is well suited for this study. Presented here is a technique by which in vivo imaging of sub-cellular structures in response to anoxic (99.999% N2; &lt;2 ppm O2) stress is possible using a simple gas flow through setup on a high-powered microscope. A microincubation chamber is used in conjunction with nitrogen gas flow through and a spinning disc confocal microscope to create a controlled environment in which animals can be imaged in vivo. Using GFP-tagged gamma tubulin and histone, the dynamics and arrest of cell division can be monitored before, during and after exposure to an oxygen-deprived environment. The results of this technique are high resolution, detailed videos and images of cellular structures within blastomeres of embryos exposed to oxygen deprivation.

C. elegans embryos exposed to severe oxygen deprivation (anoxia) are able to survive by arresting biological processes including development and cell division7. The anoxia-induced arrest of cell division can be monitored, at a sub-cellular level, by using a microincubation chamber in conjunction with nitrogen gas flow through and a spinning disc confocal microscope to create a controlled environment in which animals can be imaged in vivo (Figure 1). Cellular structures of int...

Watch this Scientific Journal Video about Use of Time Lapse Microscopy to Visualize Anoxia-induced Suspended Animation in C. elegans Embryos at JoVE.com

 University of North Texas.  Described here is an in vivo technique to image sub-cellular structures in animals exposed to anoxia using a gas flow through microincubation chamber in conjunction with a spinning disc confocal microscope. This method is straightforward and flexible enough to suit a variety of experimental parameters and model systems.

Use of Time Lapse Microscopy to Visualize Anoxia-induced Suspended Animation in C. elegans Embryos

11.5K Views.  University of North Texas. Described here is an in vivo technique to image sub-cellular structures in animals exposed to anoxia using a gas flow through microincubation chamber in conjunction with a spinning disc confocal microscope. This method is straightforward and flexible enough to suit a variety of experimental parameters and model systems.

Video: Use of Time Lapse Microscopy to Visualize Anoxia-induced Suspended Animation in C. elegans Embryos

Described here is an in vivo technique to image sub-cellular structures in animals exposed to anoxia using a gas flow through microincubation chamber in conjunction with a spinning disc confocal microscope. This method is straightforward and flexible enough to suit a variety of experimental parameters and model systems.

Use of Time Lapse Microscopy to Visualize Anoxia-induced Suspended Animation in C. elegans Embryos

Caenorhabdits elegans has been used extensively in the study of stress resistance, which is facilitated by the transparency of the adult and embryo stages ...

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Biology

Monitoring Actin Disassembly with Time-lapse Microscopy

Two-photon axotomy and time-lapse confocal imaging in live zebrafish embryos

Zebrafish have long been utilized to study the cellular and molecular mechanisms of development by time-lapse imaging of the living transparent embryo. Here we describe a method to mount zebrafish embryos for long-term imaging and demonstrate how to automate the capture of time-lapse images using a confocal microscope. We also describe a method to create controlled, precise damage to individual branches of peripheral sensory axons in zebrafish using the focused power of a femtosecond laser mounted on a two-photon microscope. The parameters for successful two-photon axotomy must be optimized for each microscope. We will demonstrate two-photon axotomy on both a custom built two-photon microscope and a Zeiss 510 confocal/two-photon to provide two examples.

Zebrafish trigeminal sensory neurons can be visualized in a transgenic line expressing GFP driven by a sensory neuron specific promoter 1. We have adapted this zebrafish trigeminal model to directly observe sensory axon regeneration in living zebrafish embryos. Embryos are anesthetized with tricaine and positioned within a drop of agarose as it solidifies. Immobilized embryos are sealed within an imaging chamber filled with phenylthiourea (PTU) Ringers. We have found that embryos can be continuously imaged in these chambers for 12-48 hours. A single confocal image is then captured to determine the desired site of axotomy. The region of interest is located on the two-photon microscope by imaging the sensory axons under low, non-damaging power. After zooming in on the desired site of axotomy, the power is increased and a single scan of that defined region is sufficient to sever the axon. Multiple location time-lapse imaging is then set up on a confocal microscope to directly observe axonal recovery from injury.

Here we describe a method for mounting zebrafish embryos for long-term imaging, two-photon imaging and tissue-damage techniques, and time-lapse confocal imaging.

Zebrafish have long been utilized to study the cellular and molecular mechanisms of development by time-lapse imaging of the living transparent embryo.  ...

Time-lapse Imaging of Mitosis After siRNA Transfection

Changes in cellular organization and chromosome dynamics that occur during mitosis are tightly coordinated to ensure accurate inheritance of genomic and cellular content. Hallmark events of mitosis, such as chromosome movement, can be readily tracked on an individual cell basis using time-lapse fluorescence microscopy of mammalian cell lines expressing specific GFP-tagged proteins. In combination with RNAi-based depletion, this can be a powerful method for pinpointing the stage(s) of mitosis where defects occur after levels of a particular protein have been lowered. In this protocol, we present a basic method for assessing the effect of depleting a potential mitotic regulatory protein on the timing of mitosis. Cells are transfected with siRNA, placed in a stage-top incubation chamber, and imaged using an automated fluorescence microscope. We describe how to use software to set up a time-lapse experiment, how to process the image sequences to make either still-image montages or movies, and how to quantify and analyze the timing of mitotic stages using a cell-line expressing mCherry-tagged histone H2B. Finally, we discuss important considerations for designing a time-lapse experiment. This strategy is complementary to other approaches and offers the advantages of 1) sensitivity to changes in kinetics that might not be observed when looking at cells as a population and 2) analysis of mitosis without the need to synchronize the cell cycle using drug treatments. The visual information from such imaging experiments not only allows the sub-stages of mitosis to be assessed, but can also provide unexpected insight that would not be apparent from cell cycle analysis by FACS.

Here we describe a basic protocol to image and quantify the mitotic timing of live mammalian tissue culture cells after siRNA transfection.

Changes in cellular organization and chromosome dynamics that occur during mitosis are tightly coordinated to ensure accurate inheritance of genomic and ...

Imaging C. elegans Embryos using an Epifluorescent Microscope and Open Source Software

Cellular processes, such as chromosome assembly, segregation and cytokinesis,are inherently dynamic. Time-lapse imaging of living cells, using fluorescent-labeled reporter proteins or differential interference contrast (DIC) microscopy, allows for the examination of the temporal progression of these dynamic events which is otherwise inferred from analysis of fixed samples1,2. Moreover, the study of the developmental regulations of cellular processes necessitates conducting time-lapse experiments on an intact organism during development. The Caenorhabiditis elegans embryo is light-transparent and has a rapid, invariant developmental program with a known cell lineage3, thus providing an ideal experiment model for studying questions in cell biology4,5and development6-9. C. elegans is amendable to genetic manipulation by forward genetics (based on random mutagenesis10,11) and reverse genetics to target specific genes (based on RNAi-mediated interference and targeted mutagenesis12-15). In addition, transgenic animals can be readily created to express fluorescently tagged proteins or reporters16,17. These traits combine to make it easy to identify the genetic pathways regulating fundamental cellular and developmental processes in vivo18-21. In this protocol we present methods for live imaging of C. elegans embryos using DIC optics or GFP fluorescence on a compound epifluorescent microscope. We demonstrate the ease with which readily available microscopes, typically used for fixed sample imaging, can also be applied for time-lapse analysis using open-source software to automate the imaging process.

Imaging C. elegans Embryos using an Epifluorescent Microscope and Open Source Software

The C. elegans embryo is a powerful system for studying cell biology and development. We present a protocol for live imaging of C. elegans embryos utilizing DIC optics or fluorescence using readily available epifluorescent microscopes and open-source software.

Cellular processes, such as chromosome assembly, segregation and cytokinesis,are inherently dynamic. Time-lapse imaging of living cells, using ...

Determining Genetic Expression Profiles in C. elegans Using Microarray and Real-time PCR

Synapses are composed of a presynaptic active zone in the signaling cell and a postsynaptic terminal in the target cell. In the case of chemical synapses, messages are carried by neurotransmitters released from presynaptic terminals and received by receptors on postsynaptic cells. Our previous research in Caenorhabditis elegans has shown that VSM-1 negatively regulates exocytosis. Additionally, analysis of synapses in vsm-1 mutants showed that animals lacking a fully functional VSM-1 have increased synaptic connectivity. Based on these preliminary findings, we hypothesized that C. elegans VSM-1 may play a crucial role in synaptogenesis. To test this hypothesis, double-labeled microarray analysis was performed, and gene expression profiles were determined. First, total RNA was isolated, reversely transcribed to cDNA, and hybridized to the DNA microarrays. Then, in-silico analysis of fluorescent probe hybridization revealed significant induction of many genes coding for members of the major sperm protein family (MSP) in mutants with enhanced synaptogenesis. MSPs are the major component of sperm in C. elegans and appear to signal nematode oocyte maturation and ovulation . In fruit flies, Chai and colleagues 1 demonstrated that MSP-like molecules regulate presynaptic bouton number and size at the neuromuscular junction. Moreover, analysis performed by Tsuda and coworkers 2 suggested that MSPs may act as ligands for Eph receptors and trigger receptor tyrosine kinase signaling cascades. Lastly, real time PCR analysis corroborated that the gene coding for MSP-32 is induced in vsm-1(ok1468) mutants. Taken together, research performed by our laboratory has shown that vsm-1 mutants have a significant increase in synaptic density, which could be mediated by MSP-32 signaling.

Determining Genetic Expression Profiles in C. elegans Using Microarray and Real-time PCR

Microarray analysis was conducted to determine genetic expression profiles in C. elegans, and real-time PCR was used to validate and quantify microarray data.

Synapses are composed of a presynaptic active zone in the signaling cell and a postsynaptic terminal in the target cell. In the case of chemical synapses, ...

Time-lapse Microscopy of Early Embryogenesis in Caenorhabditis elegans

Caenorhabditis elegans has often been used as a model system in studies of early developmental processes. The transparency of the 
embryos, the genetic resources, and the relative ease of transformation are qualities that make C. elegans an excellent model for early embryogenesis. Laser-based 
confocal microscopy and fluorescently labeled tags allow researchers to follow specific cellular structures and proteins in the developing embryo. For example, 
one can follow specific organelles, such as lysosomes or mitochondria, using fluorescently labeled dyes. These dyes can be delivered to the early embryo by means 
of microinjection into the adult gonad. Also, the localization of specific proteins can be followed using fluorescent protein tags. Examples are presented here 
demonstrating the use of a fluorescent lysosomal dye as well as fluorescently tagged histone and ubiquitin proteins. The labeled histone is used to visualize 
the DNA and thus identify the stage of the cell cycle. GFP-tagged ubiquitin reveals the dynamics of ubiquitinated vesicles in the early embryo. Observations 
of labeled lysosomes and GFP:: ubiquitin can be used to determine if there is colocalization between ubiquitinated vesicles and lysosomes. A technique for 
the microinjection of the lysosomal dye is presented. Techniques for generating transgenenic strains are presented elsewhere (1, 2). For imaging, embryos 
are cut out of adult hermaphrodite nematodes and mounted onto 2% agarose pads followed by time-lapse microscopy on a standard laser scanning confocal 
microscope or a spinning disk confocal microscope. This methodology provides for the high resolution visualization of early embryogenesis.

Time-lapse Microscopy of Early Embryogenesis in Caenorhabditis elegans

This article describes a technique for the visualization of the early events of embryogenesis in the nematode Caenorhabditis elegans.

Caenorhabditis elegans has often been used as a model system in studies of early developmental processes.  The transparency of the 
embryos, the genetic ...

RNAi Screening to Identify Postembryonic Phenotypes in C. elegans

C. elegans has proven to be a valuable model system for the discovery and functional characterization of many genes and gene pathways1. More sophisticated tools and resources for studies in this system are facilitating continued discovery of genes with more subtle phenotypes or roles. 
Here we present a generalized protocol we adapted for identifying C. elegans genes with postembryonic phenotypes of interest using RNAi2. This procedure is easily modified to assay the phenotype of choice, whether by light or fluorescence optics on a dissecting or compound microscope. This screening protocol capitalizes on the physical assets of the organism and molecular tools the C. elegans research community has produced. As an example, we demonstrate the use of an integrated transgene that expresses a fluorescent product in an RNAi screen to identify genes required for the normal localization of this product in late stage larvae and adults. First, we used a commercially available genomic RNAi library with full-length cDNA inserts. This library facilitates the rapid identification of multiple candidates by RNAi reduction of the candidate gene product. Second, we generated an integrated transgene that expresses our fluorecently tagged protein of interest in an RNAi-sensitive background. Third, by exposing hatched animals to RNAi, this screen permits identification of gene products that have a vital embryonic role that would otherwise mask a post-embryonic role in regulating the protein of interest. Lastly, this screen uses a compound microscope equipped for single cell resolution.

RNAi Screening to Identify Postembryonic Phenotypes in C. elegans

We describe a sensitized method to identify postembryonic regulators of protein expression and localization in C. elegans using an RNAi-based genomic screen and an integrated transgene that expresses a functional, fluorescently tagged protein.

C. elegans has proven to be a valuable model system for the discovery and functional characterization of many genes and gene pathways1. More sophisticated ...

Quantitative Analysis of Random Migration of Cells Using Time-lapse Video Microscopy

Cell migration is a dynamic process, which is important for embryonic development, tissue repair, immune system function, and tumor invasion 1, 2. During directional migration, cells move rapidly in response to an extracellular chemotactic signal, or in response to intrinsic cues 3 provided by the basic motility machinery. Random migration occurs when a cell possesses low intrinsic directionality, allowing the cells to explore their local environment.
Cell migration is a complex process, in the initial response cell undergoes polarization and extends protrusions in the direction of migration 2. Traditional methods to measure migration such as the Boyden chamber migration assay is an easy method to measure chemotaxis in vitro, which allows measuring migration as an end point result. However, this approach neither allows measurement of individual migration parameters, nor does it allow to visualization of morphological changes that cell undergoes during migration.
Here, we present a method that allows us to monitor migrating cells in real time using video - time lapse microscopy. Since cell migration and invasion are hallmarks of cancer, this method will be applicable in studying cancer cell migration and invasion in vitro. Random migration of platelets has been considered as one of the parameters of platelet function 4, hence this method could also be helpful in studying platelet functions. This assay has the advantage of being rapid, reliable, reproducible, and does not require optimization of cell numbers. In order to maintain physiologically suitable conditions for cells, the microscope is equipped with CO2 supply and temperature thermostat. Cell movement is monitored by taking pictures using a camera fitted to the microscope at regular intervals. Cell migration can be calculated by measuring average speed and average displacement, which is calculated by Slidebook software.

This method allows monitoring of cells in real time and quantitative measurements of different cell migration parameters such as speed, displacement, and velocity. Unlike the traditional methods, this real time approach is not based on endpoint quantitative migration measurements; instead it allows monitoring and calculating different parameters continuously.

Cell migration is a dynamic process, which is important for embryonic development, tissue repair, immune system function, and tumor invasion 1, 2. During ...

Visualization of Craniofacial Development in the sox10: kaede Transgenic Zebrafish Line Using Time-lapse Confocal Microscopy

Vertebrate palatogenesis is a highly choreographed and complex developmental process, which involves migration of cranial neural crest (CNC) cells, convergence and extension of facial prominences, and maturation of the craniofacial skeleton. To study the contribution of the cranial neural crest to specific regions of the zebrafish palate a sox10: kaede transgenic zebrafish line was generated. Sox10 provides lineage restriction of the kaede reporter protein to the neural crest, thereby making the cell labeling a more precise process than traditional dye or reporter mRNA injection. Kaede is a photo-convertible protein that turns from green to red after photo activation and makes it possible to follow cells precisely. The sox10: kaede transgenic line was used to perform lineage analysis to delineate CNC cell populations that give rise to maxillary versus mandibular elements and illustrate homology of facial prominences to amniotes. This protocol describes the steps to generate a live time-lapse video of a sox10: kaede zebrafish embryo. Development of the ethmoid plate will serve as a practical example. This protocol can be applied to making a time-lapse confocal recording of any kaede or similar photoconvertible reporter protein in transgenic zebrafish. Furthermore, it can be used to capture not only normal, but also abnormal development of craniofacial structures in the zebrafish mutants.

Visualization of experimental data has become a key element in presenting results to the scientific community. Generation of live time-lapse recording of growing embryos contributes to better presentation and understanding of complex developmental processes. This protocol is a step-by-step guide to cell labeling via photoconversion of kaede protein in zebrafish.

Vertebrate palatogenesis is a highly choreographed and complex developmental process, which involves migration of cranial neural crest (CNC) cells, ...

Methods to Assess Subcellular Compartments of Muscle in C. elegans

Muscle is a dynamic tissue that responds to changes in nutrition, exercise, and disease state. The loss of muscle mass and function with disease and age are significant public health burdens. We currently understand little about the genetic regulation of muscle health with disease or age. The nematode C. elegans is an established model for understanding the genomic regulation of biological processes of interest. This worm&#8217;s body wall muscles display a large degree of homology with the muscles of higher metazoan species. Since C. elegans is a transparent organism, the localization of GFP to mitochondria and sarcomeres allows visualization of these structures in vivo. Similarly, feeding animals cationic dyes, which accumulate based on the existence of a mitochondrial membrane potential, allows the assessment of mitochondrial function in vivo. These methods, as well as assessment of muscle protein homeostasis, are combined with assessment of whole animal muscle function, in the form of movement assays, to allow correlation of sub-cellular defects with functional measures of muscle performance. Thus, C. elegans provides a powerful platform with which to assess the impact of mutations, gene knockdown, and/or chemical compounds upon muscle structure and function. Lastly, as GFP, cationic dyes, and movement assays are assessed non-invasively, prospective studies of muscle structure and function can be conducted across the whole life course and this at present cannot be easily investigated in vivo in any other organism.

Methods to Assess Subcellular Compartments of Muscle in C. elegans

Skeletal muscle is essential for locomotion and is the bodies&#8217; main protein store. Muscle health measurements within C. elegans are described. Prospective changes to muscle structure and function are assessed using localized GFP and cationic dyes.

Muscle is a dynamic tissue that responds to changes in nutrition, exercise, and disease state. The loss of muscle mass and function with disease and age ...