Name: planarian scrunching as a quantitative behavioral readout for noxious stimuli sensing
Uploaded: 2020-07-30T14:30:00
Description: Watch this Scientific Journal Video about Planarian Scrunching as a Quantitative Behavioral Readout for Noxious Stimuli Sensing at JoVE.com

The authors thank Mr. Tapan Goel for comments on the manuscript. This work was funded by NSF CAREER Grant 1555109.

1. Quantitative planarian behavior assays
<ol>
	<li>Experimental setup
	<ol>
		<li>Place a dimmable LED panel upon a flat surface. The LED panel serves two purposes: (1) to provide a uniform white background and (2) to be used as an adjustable light source to obtain appropriate contrast. Place a 100 mm Petri dish arena upon the LED panel. 
		NOTE: To increase throughput, a multi-well plate may be used as an arena23,24, but larger arenas facilitate automate...

<ol>
	<li>Rink, 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=Stem+cell+systems+and+regeneration+in+planaria.">Stem cell systems and regeneration in planaria.</a> Development Genes and Evolution. 223, 67-84 (2013).</li><li>Reddien, P. W., Alvarado, A. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Fundamentals+of+Planarian+Regeneration.">Fundamentals of Planarian Regeneration.</a> Annual Review of Cell and Developmental Biology. 20, 725-757 (2004).</li><li>Cebri&#224;, F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Regenerating+the+central+nervous+system:+how+easy+for+planarians.">Regenerating the central nervous system: how easy for planarians.</a> Development Genes and Evolution. 217, 733-748 (2007).</li><li>Pearl, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Memoirs:+The+Movements+and+Reactions+of+Fresh-Water+Planarians:+A+Study+in+Animal+Behaviour.">Memoirs: The Movements and Reactions of Fresh-Water Planarians: A Study in Animal Behaviour.</a> Journal of Cell Science. , 2-46 (1903).</li><li>Mc Connell, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> A Manual of Psychological Experimentation on Planarians. , (1967).</li><li>Talbot, J., Sch&#246;tz, E. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Quantitative+characterization+of+planarian+wild-type+behavior+as+a+platform+for+screening+locomotion+phenotypes.">Quantitative characterization of planarian wild-type behavior as a platform for screening locomotion phenotypes.</a> Journal of Experimental Biology. 214, 1063-1067 (2011).</li><li>Cochet-Escartin, O., Mickolajczk, K. J., Collins, E. M. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Scrunching:+a+novel+escape+gait+in+planarians.">Scrunching: a novel escape gait in planarians.</a> Physical Biology. 12, 055001 (2015).</li><li>Inoue, T., 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=Planarian+shows+decision-making+behavior+in+response+to+multiple+stimuli+by+integrative+brain+function.">Planarian shows decision-making behavior in response to multiple stimuli by integrative brain function.</a> Zoological Letters. 1, 1-15 (2015).</li><li>Arenas, O. 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=Activation+of+planarian+TRPA1+by+reactive+oxygen+species+reveals+a+conserved+mechanism+for+animal+nociception.">Activation of planarian TRPA1 by reactive oxygen species reveals a conserved mechanism for animal nociception.</a> Nature Neuroscience. 20, 1686-1693 (2017).</li><li>Shomrat, T., Levin, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=An+automated+training+paradigm+reveals+long-term+memory+in+planarians+and+its+persistence+through+head+regeneration.">An automated training paradigm reveals long-term memory in planarians and its persistence through head regeneration.</a> Journal of Experimental Biology. 216, 3799-3810 (2013).</li><li>Blackiston, D., Shomrat, T., Nicolas, C. L., Granata, C., Levin, 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+Second-Generation+device+for+automated+training+and+quantitative+behavior+analyses+of+Molecularly-Tractable+model+organisms.">A Second-Generation device for automated training and quantitative behavior analyses of Molecularly-Tractable model organisms.</a> PLoS One. 5, 1-20 (2010).</li><li>Ross, K. G., Currie, K. W., Pearson, B. J., Zayas, R. 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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=SoxB1+Activity+Regulates+Sensory+Neuron+Regeneration,+Maintenance,+and+Function+in+Planarians.">SoxB1 Activity Regulates Sensory Neuron Regeneration, Maintenance, and Function in Planarians.</a> Developmental Cell. 47, 331-347 (2018).</li><li>Nishimura, K., 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=Reconstruction+of+Dopaminergic+Neural+Network+and+Locomotion+Function+in+Planarian+Regenerates.">Reconstruction of Dopaminergic Neural Network and Locomotion Function in Planarian Regenerates.</a> Developmental Neurobiology. 67, 1059-1078 (2007).</li><li>Birkholz, T. R., Beane, W. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+planarian+TRPA1+homolog+mediates+extraocular+behavioral+responses+to+near-ultraviolet+light.">The planarian TRPA1 homolog mediates extraocular behavioral responses to near-ultraviolet light.</a> Journal of Experimental Biology. 220, 2616-2625 (2017).</li><li>Currie, K. W., Molinaro, A. M., Pearson, B. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Neuronal+sources+of+hedgehog+modulate+neurogenesis+in+the+adult+planarian+brain.">Neuronal sources of hedgehog modulate neurogenesis in the adult planarian brain.</a> Elife. 5, (2016).</li><li>Talbot, J. A., Currie, K. W., Pearson, B. J., Collins, E. M. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Smed-dynA-1+is+a+planarian+nervous+system+specific+dynamin+1+homolog+required+for+normal+locomotion.">Smed-dynA-1 is a planarian nervous system specific dynamin 1 homolog required for normal locomotion.</a> Biology Open. , 1-8 (2014).</li><li>Currie, K. W., Pearson, B. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Transcription+factors+lhx1/5-1+and+pitx+are+required+for+the+maintenance+and+regeneration+of+serotonergic+neurons+in+planarians.">Transcription factors lhx1/5-1 and pitx are required for the maintenance and regeneration of serotonergic neurons in planarians.</a> Development. 140, 3577-3588 (2013).</li><li>Hagstrom, D., 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=Planarian+cholinesterase:+molecular+and+functional+characterization+of+an+evolutionarily+ancient+enzyme+to+study+organophosphorus+pesticide+toxicity.">Planarian cholinesterase: molecular and functional characterization of an evolutionarily ancient enzyme to study organophosphorus pesticide toxicity.</a> Archives of Toxicology. 92, 1161-1176 (2018).</li><li>Hagstrom, D., Cochet-Escartin, O., Collins, E. M. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Planarian+brain+regeneration+as+a+model+system+for+developmental+neurotoxicology.">Planarian brain regeneration as a model system for developmental neurotoxicology.</a> Regeneration. 3, 65-77 (2016).</li><li>Hagstrom, D., Cochet-Escartin, O., Zhang, S., Khuu, C., Collins, E. M. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Freshwater+planarians+as+an+alternative+animal+model+for+neurotoxicology.">Freshwater planarians as an alternative animal model for neurotoxicology.</a> Toxicological Sciences. 147, 270-285 (2015).</li><li>Zhang, S., Hagstrom, D., Hayes, P., Graham, A., Collins, E. M. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Multi-behavioral+endpoint+testing+of+an+87-chemical+compound+library+in+freshwater+planarians.">Multi-behavioral endpoint testing of an 87-chemical compound library in freshwater planarians.</a> Toxicological Sciences. , 26-44 (2019).</li><li>Zhang, S., Hagstrom, D., Siper, N., Behl, M., Collins, E. M. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Screening+for+neurotoxic+potential+of+15+flame+retardants+using+freshwater+planarians.">Screening for neurotoxic potential of 15 flame retardants using freshwater planarians.</a> Neurotoxicology and Teratology. 73, 54-66 (2019).</li><li>Wu, J. P., Li, M. 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+use+of+freshwater+planarians+in+environmental+toxicology+studies:+Advantages+and+potential.">The use of freshwater planarians in environmental toxicology studies: Advantages and potential.</a> Ecotoxicology and Environmental Safety. 161, 45-56 (2018).</li><li>Rompolas, P., Azimzadeh, J., Marshall, W. F., King, S. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Analysis+of+ciliary+assembly+and+function+in+planaria.">Analysis of ciliary assembly and function in planaria.</a> Methods in Enzymology. 525, 245-264 (2013).</li><li>Sabry, Z., 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=Pharmacological+or+genetic+targeting+of+Transient+Receptor+Potential+(TRP)+channels+can+disrupt+the+planarian+escape+response.">Pharmacological or genetic targeting of Transient Receptor Potential (TRP) channels can disrupt the planarian escape response.</a> PLoS One. , 753244 (2019).</li><li>Cochet-Escartin, O., Carter, J. A., Chakraverti-Wuerthwein, M., Sinha, J., Collins, E. M. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Slo1+regulates+ethanol-induced+scrunching+in+freshwater+planarians.">Slo1 regulates ethanol-induced scrunching in freshwater planarians.</a> Physical Biology. 13, 1-12 (2016).</li><li>Hagstrom, D., Truong, L., Zhang, S., Tanguay, R. L., Collins, E. M. S., 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=Comparative+analysis+of+zebrafish+and+planarian+model+systems+for+developmental+neurotoxicity+screens+using+an+87-compound+library.">Comparative analysis of zebrafish and planarian model systems for developmental neurotoxicity screens using an 87-compound library.</a> Toxicological Sciences. , (2019).</li><li>Schindelin, 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=Fiji:+an+open-source+platform+for+biological-image+analysis.">Fiji: an open-source platform for biological-image analysis.</a> Nature Methods. 9, 676-682 (2012).</li><li>Akiyama, Y., Agata, K., Inoue, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Spontaneous+Behaviors+and+Wall-Curvature+Lead+to+Apparent+Wall+Preference+in+Planarian.">Spontaneous Behaviors and Wall-Curvature Lead to Apparent Wall Preference in Planarian.</a> PLoS One. 10, 0142214 (2015).</li><li>Paskin, T. R., Jellies, J., Bacher, J., Beane, W. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Planarian+Phototactic+Assay+Reveals+Differential+Behavioral+Responses+Based+on+Wavelength.">Planarian Phototactic Assay Reveals Differential Behavioral Responses Based on Wavelength.</a> PLoS One. 9, 114708 (2014).</li><li>Petrus, 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=A+role+of+TRPA1+in+mechanical+hyperalgesia+is+revealed+by+pharmacological+inhibition.">A role of TRPA1 in mechanical hyperalgesia is revealed by pharmacological inhibition.</a> Molecular Pain. 3, 40 (2007).</li><li>Takano, T., 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=Regeneration-dependent+conditional+gene+knockdown+(Readyknock)+in+planarian:+Demonstration+of+requirement+for+Djsnap-25+expression+in+the+brain+for+negative+phototactic+behavior.">Regeneration-dependent conditional gene knockdown (Readyknock) in planarian: Demonstration of requirement for Djsnap-25 expression in the brain for negative phototactic behavior.</a> Development, Growth &amp; Differentiation. 49, 383-394 (2007).</li><li>Nishimura, K., 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=Identification+of+glutamic+acid+decarboxylase+gene+and+distribution+of+GABAergic+nervous+system+in+the+planarian+Dugesia+japonica.">Identification of glutamic acid decarboxylase gene and distribution of GABAergic nervous system in the planarian Dugesia japonica.</a> Neuroscience. 153, 1103-1114 (2008).</li><li>Inoue, T., Yamashita, T., Agata, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Thermosensory+signaling+by+TRPM+is+processed+by+brain+serotonergic+neurons+to+produce+planarian+thermotaxis.">Thermosensory signaling by TRPM is processed by brain serotonergic neurons to produce planarian thermotaxis.</a> Journal of Neuroscience. 34, 15701-15714 (2014).</li></ol>

Using this protocol, one can quantitatively study the effects of physical and chemical stimuli7,28,29 or genetic manipulation (RNAi)28,29 on planarian locomotion. To maximize spatial resolution, it is best to move the camera as close as possible to the arena while ensuring the entire arena is in the field of view. To increase throughput, the behavior of multiple planaria...

In addition to their popularity for stem cell and regeneration research1,2,3, freshwater planarians have long been used in behavioral studies4,5, taking advantage of their comparatively large size (a few millimeters in length), ease and low cost of laboratory maintenance, and broad spectrum of observable behaviors. The introduction of computer vision and automated tracking to planarian behavior studies6,7,8,9,10,11 have enabled quantitative differentiation of behavioral phenotypes. Animal behavior is a direct readout of neuronal function. Because the planarian nervous system is of medium size and complexity, but shares conserved key elements with the vertebrate brain12,13,14, studying planarian behavior can provide insight into conserved mechanisms of neuronal action which may be hard to directly probe in more complex organisms. Thus, planarians are a valuable model for comparative neurobiology studies8,12,15,16,17,18,19,20,21. In addition, the aquatic environment allows for rapid and facile exposure to chemicals to study their effect on brain function in regenerating and adult planarians, making them a popular system for neurotoxicology22,23,24,25,26.
Planarians possess three distinct gaits, referred to as gliding, peristalsis, and scrunching. Each gait is exhibited under specific circumstances: gliding is the default gait, peristalsis occurs when ciliary function is compromised7,27, and scrunching is an escape gait &#8211; independent of cilia function &#8211; in response to certain noxious stimuli7. We have shown that scrunching is a specific response, elicited by the sensation of certain chemical or physical cues, including extreme temperatures or pH, mechanical injury, or specific chemical inducers, and thus is not a general stress response7,28,29.
Because of its specificity and stereotypical parameters, which can easily be quantified using this protocol, scrunching is a powerful behavioral phenotype that enables researchers to perform mechanistic studies dissecting sensory pathways and neuronal control of behavior25,28. Additionally, scrunching has been shown to be a sensitive endpoint to assay adverse chemical effects on nervous system development and function in neurotoxicology studies22,24,25,30. As several different sensory pathways seem to converge to induce scrunching through various mechanisms28, scrunching differs from other planarian behaviors because various, but specific, stimuli can be used to dissect distinct neuronal circuits and study how different signals are integrated to produce the scrunching phenotype.
Importantly, species differences exist, wherein one chemical may elicit scrunching in one planarian species, but a different behavioral response in another. For example, we have found that anandamide induces scrunching in the planarian species Dugesia japonica but induces peristalsis in Schmidtea mediterranea28. This example highlights the importance of being able to reliably distinguish between the different gaits, because they are the phenotypic manifestations of distinct molecular mechanisms. However, distinction of scrunching from peristalsis is difficult using qualitative observational data, because both gaits are musculature-driven and share qualitative similarities7,28. Thus, to distinguish the gaits it is necessary to perform cilia imaging or a quantitative behavioral study, which allows distinction based on characteristic parameters7,28. Because cilia imaging is experimentally challenging and requires specialized equipment such as a high-magnification compound microscope and a high-speed camera7,28, it is not as broadly accessible to researchers as quantitative behavioral analysis.
Here, we present a protocol for (1) the induction of scrunching using various physical (noxious temperature, amputation, near-UV light) and chemical (allyl isothiocyanate (AITC), cinnamaldehyde) stimuli and (2) the quantitative analysis of planarian behavior using freely available software. By quantifying four parameters (frequency of body length oscillations, relative speed, maximum amplitude, and asymmetry of body elongation and contraction)7, scrunching can be differentiated from gliding, peristalsis, and other behavioral states reported in the literature, such as snake-like locomotion15 or epilepsies15. Furthermore, while scrunching is conserved among different planarian species7, each species has its own characteristic frequency and speed; therefore, once the gliding and scrunching speeds of a species have been determined, speed alone can be used as a means to distinguish scrunching from gliding and peristalsis29. The protocol assumes no prior training in computational image analysis or behavioral studies and thus can also be applied for planarian behavioral experiments in a teaching laboratory context at the undergraduate level. Example data to facilitate protocol adaptation is provided in the Supplemental Material.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>Allyl isothiocyanate, 95% (AITC)</td>
			<td>Sigma-Aldrich</td>
			<td>377430-5G</td>
			<td>CAUTION:&#160; Flammable and acutely toxic; handle in a fume hood with appropriate PPE.</td>
		</tr>
		<tr>
			<td>Camera lens, 2/3 25mm F/1.4&#160;</td>
			<td>Tamron</td>
			<td>23FM25SP</td>
			<td></td>
		</tr>
		<tr>
			<td>Cell culture plates, 6 well, tissue culture treated</td>
			<td>Genesee Scientific&#160;</td>
			<td>25-105</td>
			<td></td>
		</tr>
		<tr>
			<td>Centrifuge tubes, 50 mL polypropylene, sterile</td>
			<td>MedSupply Partners</td>
			<td>62-1019-2</td>
			<td></td>
		</tr>
		<tr>
			<td>Cinnamaldehyde, &#62;95%</td>
			<td>Sigma-Aldrich</td>
			<td>W228613-100G-K</td>
			<td></td>
		</tr>
		<tr>
			<td>Dimmable A4 LED Tracer Light Box</td>
			<td>Amazon</td>
			<td>B07HD631RP</td>
			<td></td>
		</tr>
		<tr>
			<td>Flea3 USB3 camera</td>
			<td>FLIR</td>
			<td>FL3-U3-13E4M</td>
			<td></td>
		</tr>
		<tr>
			<td>Heat resistant gloves</td>
			<td>Fisher Scientific</td>
			<td>11-394-298</td>
			<td></td>
		</tr>
		<tr>
			<td>Hot plate</td>
			<td>Fisher Scientific</td>
			<td>HP88854200</td>
			<td></td>
		</tr>
		<tr>
			<td>Instant Ocean Sea Salt, prepared in deionized water</td>
			<td>Instant Ocean</td>
			<td>SS15-10</td>
			<td>Prepare in deionized water at 0.5 g/L.</td>
		</tr>
		<tr>
			<td>Montj&#252;ic salts, prepared in Milli-Q water</td>
			<td>Sigma-Aldrich</td>
			<td>various</td>
			<td>Prepare in milli-Q water at 1.6 mM NaCl, 1.0 mM CaCl2, 1.0 mM MgSO4, 0.1 mM MgCl2, 0.1 mM KCl, 1.2 mM NaHCO3; adjust pH to 7.0 with HCl.</td>
		</tr>
		<tr>
			<td>Petri dishes, 100 mm x 20 mm, sterile polystyrene</td>
			<td>Simport</td>
			<td>D210-7</td>
			<td></td>
		</tr>
		<tr>
			<td>Pipette, 20-200 &#956;L range</td>
			<td>Rainin</td>
			<td>17008652</td>
			<td></td>
		</tr>
		<tr>
			<td>PYREX 150 mL beaker</td>
			<td>Sigma-Aldrich</td>
			<td>CLS1000150</td>
			<td></td>
		</tr>
		<tr>
			<td>Razor blade, 0.22 mm</td>
			<td>VWR</td>
			<td>55411-050</td>
			<td></td>
		</tr>
		<tr>
			<td>Roscolux color filter:&#160; Golden Amber</td>
			<td>Rosco</td>
			<td>R21</td>
			<td>Alternatively purchase the Roscolux Designer Color Selector (Musson Theatrical product #SBLUX0306) which includes all 3 color filters together.</td>
		</tr>
		<tr>
			<td>Roscolux color filter:&#160; Medium Red</td>
			<td>Rosco</td>
			<td>R27</td>
			<td></td>
		</tr>
		<tr>
			<td>Roscolux color filter:&#160; Storaro Red</td>
			<td>Rosco</td>
			<td>R2001</td>
			<td></td>
		</tr>
		<tr>
			<td>Samco transfer pipette, 62 &#181;L large aperture</td>
			<td>Thermo Fisher</td>
			<td>691TS</td>
			<td></td>
		</tr>
		<tr>
			<td>Support stand&#160;</td>
			<td>Fisher Scientific</td>
			<td>12-947-976</td>
			<td></td>
		</tr>
		<tr>
			<td>Thermometer</td>
			<td>VWR</td>
			<td>89095-600</td>
			<td></td>
		</tr>
		<tr>
			<td>UV laser pointer</td>
			<td>Amazon</td>
			<td>B082DGS86R</td>
			<td>This is a Class II laser (405nm &#177;10nm) with output power &#60;5 mW.</td>
		</tr>
	</tbody>
</table>

planarian scrunching as a quantitative behavioral readout for noxious stimuli sensing

Freshwater planarians normally glide smoothly through ciliary propulsion on their ventral side. Certain environmental conditions, however, can induce musculature-driven forms of locomotion: peristalsis or scrunching. While peristalsis results from a ciliary defect, scrunching is independent of cilia function and is a specific response to certain stimuli, including amputation, noxious temperature, extreme pH, and ethanol. Thus, these two musculature-driven gaits are mechanistically distinct. However, they can be difficult to distinguish qualitatively. Here, we provide a protocol for inducing scrunching using various physical and chemical stimuli. We detail the quantitative characterization of scrunching, which can be used to distinguish it from peristalsis and gliding, using freely available software. Since scrunching is a universal planarian gait, albeit with characteristic species-specific differences, this protocol can be broadly applied to all species of planarians, when using appropriate considerations. To demonstrate this, we compare the response of the two most popular planarian species used in behavioral research, Dugesia japonica and Schmidtea mediterranea, to the same set of physical and chemical stimuli. Furthermore, the specificity of scrunching allows this protocol to be used in conjunction with RNA interference and/or pharmacological exposure to dissect the molecular targets and neuronal circuits involved, potentially providing mechanistic insight into important aspects of nociception and neuromuscular communication.

Extraocular near-UV perception in S. mediterranea planarians is TRPA1-dependent and has been proposed to be linked to H2O2 release17. Because H2O2 exposure induces TRPA1-dependent scrunching in S. mediterranea and D. japonica planarians28, the steps in Section 2.1.4 can be used to test whether near-UV light exposure induces scrunching in both species. While D. japonica planarians scrunch (10/10)...

Watch this Scientific Journal Video about Planarian Scrunching as a Quantitative Behavioral Readout for Noxious Stimuli Sensing at JoVE.com

Planarian Scrunching as a Quantitative Behavioral Readout for Noxious Stimuli Sensing

Freshwater planarians exhibit three gaits (gliding, peristalsis, and scrunching) that are distinguishable by quantitative behavioral analysis. We describe a method to induce scrunching using various noxious stimuli, quantification thereof, and distinction from peristalsis and gliding. Using gene knockdown, we demonstrate the specificity of scrunching as a quantitative phenotypic readout.

Freshwater planarians normally glide smoothly through ciliary propulsion on their ventral side. Certain environmental conditions, however, can induce ...

This protocol allows researchers to clarify planarian behavior and the sec mechanisms underlying this behavior by combining quantitative behavioral analysis with molecular and chemical perturbations. This technique is easily accessible to all skill levels as it does not require advanced instruments or specialized software to get quantitative behavioral readouts of free moving planarians. Scrunching can be used to study exception in planarians, and serves as sensitive endpoint to assay, disrupting nervous system function caused by Xenobiotics and disease.Begin by placing a dimmable LED Panel upon a flat surface, which will provide a uniform white background and can be used as an adjustable light source to obtain appropriate contrast. Place a 100 millimeter Petri dish arena on the LED Panel. Mount a camera on a ring stand above the arena and adjust its position, height and focus as necessary so that the entire arena is centered within the field of view and is in focus.Fill the arena with approximately 25 milliliters of the appropriate exposure media to have maximum volume, turn on the LED Panel and turn off any other light sources that may negatively affect recording quality. Drop a planarian at the center of the arena using a transfer Pipette. When testing a chemical solution, transfer the planarian with as little of planarian water as possible, so that the concentration of the chemical is not significantly changed.Begin recording data as image sequences in a native Fiji format. For gliding experiments, record one to two minutes of gliding behavior, for scrunching or peristalsis experiments, record long enough to capture at least three consecutive oscillations occurring in a straight line. Once the experiment is completed, terminate the recording.If the planarian reaches the boundary of the arena without satisfying the termination criterion, pipette the planarian back to the center of the arena. Open the raw image sequence for an experiment in Fiji, convert it to eight bit and use the arrow tool or slider at the bottom of the image stack to pan through the image sequence. To extract a time period and region of interest, draw a region of interest encompassing the full path of a planarian using the rectangle tool.Right click on the image stack and select duplicate, check the box where duplicate stack. Enter the first and last frames of the sequence of interest and click okay. For gliding experiments, extract a period of gliding where the planarian moves at least twice its body length for scrunching or peristalsis experiments.Extract an instance when the planarian undergoes a minimum of three consecutive and complete body oscillations in a straight line. Apply a threshold to the duplicated image stack to binarize the image and extract the planarian from the background, adjust the sliding bars so that the entire planarian is highlighted in red. The exact values are dependent on imaging quality.Leave the boxes for dark background, stack histogram and don't reset range unchecked. Scroll through the image stack to ensure a good threshold range and then click apply. In the convert stack to binary window, set the method to default and the background to light.Uncheck all boxes in this window and then click okay. A binarized image showing a black planarian on a white background will appear. Make sure that the entire planarian is visible in all frames of the image sequence.Set measurements by clicking analyze and set measurements. Check the boxes for area, center of mass, stack position and fit ellipse, then click okay. Select the open image stack and select analyze, and analyze particles.In the analyze particles window, select show and masks to open a new stack showing all the objects that were detected with the chosen parameters. Set a size filter to remove unwanted noise by entering the approximate area of the planarian. Then check the boxes for display results and clear results and click okay.Pan through the mask image stack using the slider at the bottom of the Panel to make sure that there is no noise or frames without a planarian. On the results window, save the data using file and save as, add the CSV extension to the file name, to save the data as comma separated values. Once the data for the image stack is saved, close the respective image stack results and mask windows.To induce scrunching via noxious temperature, heat planarian water in a glass beaker to 65 degrees Celsius on a hot plate. Place a planarian in the center of the arena, and wait until it orients itself upright and begins gliding, then begin recording. Use a P 200 Pipette to slowly and consistently pipette 100 microliters of the preheated planarian water, post pharyngeal onto the tail end of the planarian to induce scrunching.Stop the recording, once scrunching has ceased. Place the planarian in a recovery container and exchange the media in the Petri dish with fresh room temperature planarian water, if running more experiments. To induce scrunching via amputation, transfer a planarian to the center of the arena and wait until the planarian orients itself upright and begins gliding.Then begin recording, amputate the planarian with a clean razor blade. Making sure that the cut location is consistent across experiments. Stop the recording once the anterior piece has ceased scrunching.Remove both pieces, place them in a separate container and allow them to regenerate for seven days. Amputated planarians can be reincorporated into the home container once they have regenerated. This protocol was used to test whether near UV light exposure, induces scrunching in S.mediterranea and D.japonica planarians, while D.japonica planarians scrunch, when exposed to near UV light, S.mediterranea planarians either exhibit tail thinning or no response.A quantification of the scrunching parameters for the D.japonica planarians that exhibited at least three consecutive straight line scrunches, reveals characteristics scrunching parameters for this species In contrast exposure to 250 micromolar cinnamaldehyde unknown TRPA one agonist in mice, causes scrunching and S.mediterranea. Whereas D.japonica planarians display a mixture of snake-like and oscillatory motion interrupted by gliding or vigorous head turns. A quantification of the samples with at least three consecutive oscillations, yielded significantly lower values for three out of four parameters then expected for scrunching in D.japonica, indicating that the observed oscillatory motion is not scrunching.RNAi confirms the specificity of scrunching and response to cinnamaldehyde exposure in S.mediterranea. Within 180 seconds of exposure in planarian water, all control RNAi planarian scrunched. Compared to none of the SMTRPA one RNAi planarians demonstrating that S.mediterranea scrunching in cinnamaldehyde requires SMTRPA one.It is essential to be consistent and how the animals are manipulated to reduce noise and ensure reproducibility in the behavioral measurements. This projects can be expanded to include body shape analysis, which would allow for identification and quantification of other planarian behaviors that are not captured here.

planarian-scrunching-as-quantitative-behavioral-readout-for-noxious

Research

JoVE Journal

Biology

Computer-Generated Animal Model Stimuli

Communication between animals is diverse and complex. Animals may communicate using auditory, seismic, chemosensory, electrical, or visual signals. In particular, understanding the constraints on visual signal design for communication has been of great interest. Traditional methods for investigating animal interactions have used basic observational techniques, staged encounters, or physical manipulation of morphology. Less intrusive methods have tried to simulate conspecifics using crude playback tools, such as mirrors, still images, or models. As technology has become more advanced, video playback has emerged as another tool in which to examine visual communication (Rosenthal, 2000). However, to move one step further, the application of computer-animation now allows researchers to specifically isolate critical components necessary to elicit social responses from conspecifics, and manipulate these features to control interactions. Here, I provide detail on how to create an animation using the Jacky dragon as a model, but this process may be adaptable for other species. In building the animation, I elected to use Lightwave  3D to alter object morphology, add texture, install bones, and provide comparable weight shading that prevents exaggerated movement. The animation is then matched to select motor patterns to replicate critical movement features. Finally, the sequence must rendered into an individual clip for presentation. Although there are other adaptable techniques, this particular method had been demonstrated to be effective in eliciting both conspicuous and social responses in staged interactions.

Computer-generated stimuli using the Jacky dragon as a model.

Communication between animals is diverse and complex. Animals may communicate using auditory, seismic, chemosensory, electrical, or visual signals. In ...

Use of Rotorod as a Method for the Qualitative Analysis of Walking in Rat

High speed videoanalysis of the details of movement can provide a source of information about qualitative aspects of walking movements. When walking on a rotorod, animals remain in approximately the same place making repetitive movements of stepping. Thus the task provides a rich source of information on the details of foot stepping movements. Subjects were hemi-Parkinson analogue rats, produced by injection of 6-hydroxydopamine (6-OHDA) into the right nigrostriatal bundle to deplete nigrostriatal dopamine (DA). The present report provides a video analysis illustration of animals previously were filmed from frontal, lateral, and posterior views as they walked (15). Rating scales and frame-by-frame replay of the video records of stepping behavior indicated that the hemi-Parkinson rats were chronically impaired in posture and limb use contralateral to the DA-depletion. The contralateral limbs participated less in initiating and sustaining propulsion than the ipsilateral limbs. These deficits secondary to unilateral DA-depletion show that the rotorod provides a use task for the analysis of stepping movements.

The rotorod test is used to assess motor status in the walking movement of hemi-Parkinson analogue rats.

High speed videoanalysis of the details of movement can provide a source of information about qualitative aspects of walking movements. When walking on a ...

Quantitative Phosphoproteomics in Fatty Acid Stimulated Saccharomyces cerevisiae

This protocol describes the growth and stimulation, with the fatty acid oleate, of isotopically heavy and light S. cerevisiae cells. Cells are ground using a cryolysis procedure in a ball mill grinder and the resulting grindate brought into solution by urea solubilization. This procedure allows for the lysis of the cells in a metabolically inactive state, preserving phosphorylation and preventing reorientation of the phosphoproteome during cell lysis.  Following reduction, alkylation, trypsin digestion of the proteins, the samples are desalted on C18 columns and the sample complexity reduced by fractionation using hydrophilic interaction chromatography (HILIC). HILIC columns preferentially retain hydrophilic molecules which is well suited for phosphoproteomics.  Phosphorylated peptides tend to elute later in the chromatographic profile than the non phosphorylated counterparts. After fractionation, phosphopeptides are enriched using immobilized metal chromatography, which relies on charge-based affinities for phosphopeptide enrichment. At the end of this procedure the samples are ready to be quantitatively analyzed by mass spectrometry.

Quantitative Phosphoproteomics in Fatty Acid Stimulated Saccharomyces cerevisiae

Description of a quantitative phosphorylation procedure using cryolysis, urea solubilziation, HILIC fractionation and IMAC enrichment of phosphorylated peptides.

This protocol describes the growth and stimulation, with the fatty acid oleate, of isotopically heavy and light S. cerevisiae cells. Cells are ground ...

A Quantitative Assay for Insulin-expressing Colony-forming Progenitors

The field of pancreatic stem and progenitor cell biology has been hampered by a lack of in vitro functional and quantitative assays that allow for the analysis of the single cell. Analyses of single progenitors are of critical importance because they provide definitive ways to unequivocally demonstrate the lineage potential of individual progenitors. Although methods have been devised to generate "pancreatospheres" in suspension culture from single cells, several limitations exist. First, it is time-consuming to perform single cell deposition for a large number of cells, which in turn commands large volumes of culture media and space. Second, numeration of the resulting pancreatospheres is labor-intensive, especially when the frequency of the pancreatosphere-initiating progenitors is low. Third, the pancreatosphere assay is not an efficient method to allow both the proliferation and differentiation of pancreatic progenitors in the same culture well, restricting the usefulness of the assay.
To overcome these limitations, a semi-solid media based colony assay for pancreatic progenitors has been developed and is presented in this report. This method takes advantage of an existing concept from the hematopoietic colony assay, in which methylcellulose is used to provide viscosity to the media, allowing the progenitor cells to stay in three-dimensional space as they undergo proliferation as well as differentiation. To enrich insulin-expressing colony-forming progenitors from a heterogeneous population, we utilized cells that express neurogenin (Ngn) 3, a pancreatic endocrine progenitor cell marker. Murine embryonic stem (ES) cell-derived Ngn3 expressing cells tagged with the enhanced green fluorescent protein reporter were sorted and as many as 25,000 cells per well were plated into low-attachment 24-well culture dishes. Each well contained 500 &mu;L of semi-solid media with the following major components: methylcellulose, Matrigel, nicotinamide, exendin-4, activin &beta;B, and conditioned media collected from murine ES cell-derived pancreatic-like cells. After 8 to 12 days of culture, insulin-expressing colonies with distinctive morphology were formed and could be further analyzed for pancreatic gene expression using quantitative RT-PCR and immunoflourescent staining to determine the lineage composition of each colony.
In summary, our colony assay allows easy detection and quantification of functional progenitors within a heterogeneous population of cells. In addition, the semi-solid media format allows uniform presentation of extracellular matrix components and growth factors to cells, enabling progenitors to proliferate and differentiate in vitro. This colony assay provides unique opportunities for mechanistic studies of pancreatic progenitor cells at the single cell level.

A three-dimensional clonogenic assay that allows pancreatic-like progenitors to differentiate into insulin-expressing colonies is described. This method takes advantage of semi-solid media containing methylcellulose, Matrigel and growth factors, in which single progenitors proliferate and differentiate in vitro, permitting quantification of the number of functional progenitors in a population.

The field of pancreatic stem and progenitor cell biology has been hampered by a lack of in vitro functional and quantitative assays that allow for the ...

Planarian Immobilization, Partial Irradiation, and Tissue Transplantation

The planarian, a freshwater flatworm, has proven to be a powerful system for dissecting metazoan regeneration and stem cell biology1,2. Planarian regeneration of any missing or damaged tissues is made possible by adult stem cells termed neoblasts3. Although these stem cells have been definitively shown to be pluripotent and singularly capable of reconstituting an entire animal4, the heterogeneity within the stem cell population and the dynamics of their cellular behaviors remain largely unresolved. Due to the large number and wide distribution of stem cells throughout the planarian body plan, advanced methods for manipulating subpopulations of stem cells for molecular and functional study in vivo are needed.
Tissue transplantation and partial irradiation are two methods by which a subpopulation of planarian stem cells can be isolated for further study. Each technique has distinct advantages. Tissue transplantation allows for the introduction of stem cells, into a na&iuml;ve host, that are either inherently genetically distinct or have been previously treated pharmacologically. Alternatively, partial irradiation allows for the isolation of stem cells within a host, juxtaposed to tissue devoid of stem cells, without the introduction of a wound or any breech in tissue integrity. Using these two methods, one can investigate the cell autonomous and non-autonomous factors that control stem cell functions, such as proliferation, differentiation, and migration.
Both tissue transplantation5,6 and partial irradiation7 have been used historically in defining many of the questions about planarian regeneration that remain under study today. However, these techniques have remained underused due to the laborious and inconsistent nature of previous methods. The protocols presented here represent a large step forward in decreasing the time and effort necessary to reproducibly generate large numbers of grafted or partially irradiated animals with efficacies approaching 100 percent. We cover the culture of large animals, immobilization, preparation for partial irradiation, tissue transplantation, and the optimization of animal recovery. Furthermore, the work described here demonstrates the first application of the partial irradiation method for use with the most widely studied planarian, Schmidtea mediterranea. Additionally, efficient tissue grafting in planaria opens the door for the functional testing of subpopulations of na&iuml;ve or treated stem cells in repopulation assays, which has long been the gold-standard method of assaying adult stem cell potential in mammals8. Broad adoption of these techniques will no doubt lead to a better understanding of the cellular behaviors of adult stem cells during tissue homeostasis and regeneration.

An effective method for grafting tissue of defined and consistent size between planaria is described. Also included is a description of how the immobilization technique used for transplantation can be adapted, in conjunction with lead shields, for the partial irradiation of live animals.

The planarian, a freshwater flatworm, has proven to be a powerful system for dissecting metazoan regeneration and stem cell biology1,2. Planarian ...

A Quantitative Fitness Analysis Workflow

Quantitative Fitness Analysis (QFA) is an experimental and computational workflow for comparing fitnesses of microbial cultures grown in parallel1,2,3,4. QFA can be applied to focused observations of single cultures but is most useful for genome-wide genetic interaction or drug screens investigating up to thousands of independent cultures. The central experimental method is the inoculation of independent, dilute liquid microbial cultures onto solid agar plates which are incubated and regularly photographed. Photographs from each time-point are analyzed, producing quantitative cell density estimates, which are used to construct growth curves, allowing quantitative fitness measures to be derived. Culture fitnesses can be compared to quantify and rank genetic interaction strengths or drug sensitivities. The effect on culture fitness of any treatments added into substrate agar (e.g. small molecules, antibiotics or nutrients) or applied to plates externally (e.g. UV irradiation, temperature) can be quantified by QFA.
The QFA workflow produces growth rate estimates analogous to those obtained by spectrophotometric measurement of parallel liquid cultures in 96-well or 200-well plate readers. Importantly, QFA has significantly higher throughput compared with such methods. QFA cultures grow on a solid agar surface and are therefore well aerated during growth without the need for stirring or shaking.
QFA throughput is not as high as that of some Synthetic Genetic Array (SGA) screening methods5,6. However, since QFA cultures are heavily diluted before being inoculated onto agar, QFA can capture more complete growth curves, including exponential and saturation phases3. For example, growth curve observations allow culture doubling times to be estimated directly with high precision, as discussed previously1.
Here we present a specific QFA protocol applied to thousands of S. cerevisiae cultures which are automatically handled by robots during inoculation, incubation and imaging. Any of these automated steps can be replaced by an equivalent, manual procedure, with an associated reduction in throughput, and we also present a lower throughput manual protocol. The same QFA software tools can be applied to images captured in either workflow.
We have extensive experience applying QFA to cultures of the budding yeast S. cerevisiae but we expect that QFA will prove equally useful for examining cultures of the fission yeast S. pombe and bacterial cultures.

Quantitative Fitness Analysis (QFA) is a complementary series of experimental and computational methods for estimating microbial culture fitnesses. QFA estimates the effect of genetic mutations, drugs or other applied treatments on microbe growth. Experiments scaling from focussed analysis of single cultures to thousands of parallel cultures can be designed.

Quantitative Fitness Analysis (QFA) is an experimental and computational workflow for comparing fitnesses of microbial cultures grown in parallel1,2,3,4. ...

A Strategy for Sensitive, Large Scale Quantitative Metabolomics

Metabolite profiling has been a valuable asset in the study of metabolism in health and disease. However, current platforms have different limiting factors, such as labor intensive sample preparations, low detection limits, slow scan speeds, intensive method optimization for each metabolite, and the inability to measure both positively and negatively charged ions in single experiments. Therefore, a novel metabolomics protocol could advance metabolomics studies. Amide-based hydrophilic chromatography enables polar metabolite analysis without any chemical derivatization. High resolution MS using the Q-Exactive (QE-MS) has improved ion optics, increased scan speeds (256 msec at resolution 70,000), and has the capability of carrying out positive/negative switching. Using a cold methanol extraction strategy, and coupling an amide column with QE-MS enables robust detection of 168 targeted polar metabolites and thousands of additional features simultaneously.&#160; Data processing is carried out with commercially available software in a highly efficient way, and unknown features extracted from the mass spectra can be queried in databases.

Metabolite profiling has been a valuable asset in the study of metabolism in health and disease. Utilizing normal-phased liquid chromatography coupled to high-resolution mass spectrometry with polarity switching and a rapid duty cycle, we describe a protocol to analyze the polar metabolic composition of biological material with high sensitivity, accuracy, and resolution.

Metabolite profiling has been a valuable asset in the study of metabolism in health and disease. However, current platforms have different limiting ...

Simple Bulk Readout of Digital Nucleic Acid Quantification Assays

Digital assays are powerful methods that enable detection of rare cells and counting of individual nucleic acid molecules. However, digital assays are still not routinely applied, due to the cost and specific equipment associated with commercially available methods. Here we present a simplified method for readout of digital droplet assays using a conventional real-time PCR instrument to measure bulk fluorescence of droplet-based digital assays.
We characterize the performance of the bulk readout assay using synthetic droplet mixtures and a droplet digital multiple displacement amplification (MDA) assay. Quantitative MDA particularly benefits from a digital reaction format, but our new method&#160;applies to any digital assay. For established digital assay protocols such as digital PCR, this method serves to speed up and simplify assay readout.
Our bulk readout methodology brings the advantages of partitioned assays without the need for specialized readout instrumentation. The principal limitations of the bulk readout methodology are reduced dynamic range compared with droplet-counting platforms and the need for a standard sample, although the requirements for this standard are less demanding than for a conventional real-time experiment. Quantitative whole genome amplification (WGA) is used to test for contaminants in WGA reactions and is the most sensitive way to detect the presence of DNA fragments with unknown sequences, giving the method great promise in diverse application areas including pharmaceutical quality control and astrobiology.

We describe an endpoint digital assay for quantifying nucleic acids with a simplified (analog) readout. We measure bulk fluorescence of droplet-based digital assays using a standard qPCR machine rather than specialized instrumentation and confirm our results by microscopy.

Digital assays are powerful methods that enable detection of rare cells and counting of individual nucleic acid molecules. However, digital assays are ...

FRET Imaging in Three-dimensional Hydrogels

Imaging of F&#246;rster resonance energy transfer (FRET)&#160;is a powerful tool for examining cell biology in real-time. Studies utilizing FRET commonly employ two-dimensional (2D) culture, which does not mimic the three-dimensional (3D) cellular microenvironment. A method to perform quenched emission FRET imaging using conventional widefield epifluorescence microscopy of cells within a 3D hydrogel environment is presented. Here an analysis method for ratiometric FRET probes that yields linear ratios over the probe activation range is described. Measurement of intracellular cyclic adenosine monophosphate (cAMP) levels is demonstrated in chondrocytes under forskolin stimulation using a probe for EPAC1 activation (ICUE1) and the ability to detect differences in cAMP signaling dependent on hydrogel material type, herein a photocrosslinking hydrogel (PC-gel, polyethylene glycol dimethacrylate) and a thermoresponsive hydrogel (TR-gel). Compared with 2D FRET methods, this method requires little additional work. Laboratories already utilizing FRET imaging in 2D can easily adopt this method to perform cellular studies in a 3D microenvironment. It can further be applied to high throughput drug screening in engineered 3D microtissues. Additionally, it is compatible with other forms of FRET imaging, such as anisotropy measurement and fluorescence lifetime imaging (FLIM), and with advanced microscopy platforms using confocal, pulsed, or modulated illumination.

F&#246;rster resonance energy transfer (FRET) imaging is a powerful tool for real-time cell biology studies. Here a method for FRET imaging cells in physiologic three-dimensional (3D) hydrogel microenvironments using conventional epifluorescence microscopy is presented. An analysis for ratiometric FRET probes that yields linear ratios over the activation range is described.

Imaging of F&#246;rster resonance energy transfer (FRET)&#160;is a powerful tool for examining cell biology in real-time. Studies utilizing FRET commonly ...

Discrimination and Characterization of Heterocellular Populations Using Quantitative Imaging Techniques

Cellular processes are complex and result from the interplay between multiple cell types and their environment. Existing cell biology techniques often do not allow for accurate interpretation of this interplay. Using a quantitative imaging-based approach, we present a high-content protocol for characterizing the dynamic phenotypic responses (i.e. morphology changes, proliferation, apoptosis) of heterogeneous cell populations to changes in environmental stimuli. We highlight our ability to distinguish between cell types based upon either fluorescence intensity or inherent morphology features depending on the application. This platform allows for a more comprehensive characterization of subpopulation response to perturbation while utilizing shorter time, smaller amounts of reagents, and lower likelihood of error than traditional cell biology assays. However, in some cases, cell populations may be difficult to identify and quantitate based on complex cellular features and will require additional troubleshooting; we highlight some of these circumstances in the protocol. We demonstrate this application using response to drug in a cancer model; however, it can easily be applied more broadly to other physiological processes. This protocol allows one to identify subpopulations within a co-culture system and characterize the particular response of each to external stimuli.

We have developed a novel protocol for studying heterocellular population dynamics in response to perturbations. This manuscript describes an imaging-based platform that produces quantitative datasets for simultaneous characterization of multiple cellular phenotypes of heterocellular populations in a robust manner.

Cellular processes are complex and result from the interplay between multiple cell types and their environment. Existing cell biology techniques often do ...