This research was supported by the National Institutes of Health CounterACT Program Interagency Agreement# AOD13015-001. We would like to thank Stephanie Froberg and Peter Hurst for their efforts and expertise on video production.

<ol>
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The authors have nothing to disclose.
DISCLAIMER: The views expressed in this article are those of the author(s) and do not reflect the official policy of the Department of Army, Department of Defense, or the U.S. Government. This research was supported by an interagency agreement between NIH/NIAID and the USAMRICD, and in part by an appointment to the Postgraduate Research Participation Program at the U.S. Army Medical Research Institute of Chemical Defense administered by the Oak Ridge Institute for Science and Education through an interagency agreement between the U.S. Department of Energy and USAMRMC.

Herein we describe our methods and results on the development of a high throughput cornea epithelial cell screening model for the study of HF and CP injuries. We also present the results from the primary siRNA screen for HF injury. There were many challenges to the development of HTS models for the study of TIC injuries. Methods that we could find in the literature related to the study of HF, HFA or CP in cell culture models were of little help. Most in vitro studies on the fluoride ion involve oral cells and utilized sodium fluoride and not HF or HFA (for some examples, see28,29). Some methodology on the in vitro exposure of bronchial epithelial cells to CP has been published by Pesonen et al.30. Ultimately, we found no specific methods in the literature related to the HTS study of HF, HFA or CP, and the vast majority of challenges and variables related to the study of these toxicants in HTS required development. Particular attention was paid to achieving the high degree of exposure consistency across time and numerous screening plates necessary for a successful HTS study.
One type of challenge encountered was related to the application of toxicant to cell culture systems. Some toxicants are either reactive with or unstable in aqueous solutions. The toxicants we selected for study are not regarded as having these instability issues. An agricultural study investigating photohydrolysis of CP showed that a 0.001 M solution of CP in water had a half-life of 31.1 h when exposed to an 1100 lux xenon light source (sunlight intensity of an overcast day) for 10 days, 12 h per day31. There was no measurable hydrolysis over the same 10 day period when the solution was stored in the dark. The proton and fluoride ion of HFA are clearly stable in water. There are, however, additional stability considerations with regard to toxicant dilutions made in cell culture medium. We found that there was an initial change of cytotoxicity to some degree when the toxicants were first diluted in cell culture medium that then stabilizes after a brief period of time. We believe that this is due to the toxicant binding or complexing with constituents in the medium. Cell medium contains calcium, magnesium, protein, etc. that are known to interact with the fluoride ion32,33. CP is known to have oxidative reactions with biological thiols, but it may also bind DNA, proteins, and other nucleophiles34,35. Once these reactions and interactions have completed or reached equilibrium, the amount of available toxicant stabilizes and thus the apparent cytotoxicity stabilizes. We initially explored the use of saline and water dilutions of toxicants for working stocks used for exposures to avoid toxicant interactions with medium constituents in working dilutions. The use of saline would also preserve the acid component of HFA injury for exposures performed by medium exchange. We found that the cell death responses to toxicants in water and saline dilutions were more variable than the method that used cell culture medium dilutions with medium exchange (data not shown). Regarding the spike exposure method with HFA, the variability may be due to inconsistency in the spike dispersing in the well leading to cellular targets competing with medium constituents for the available fluoride ion. The reasons for the variability in HFA exposures by medium exchange with HFA saline dilutions are entirely unclear. In any event, exposure methods using saline dilutions for HFA were abandoned and not explored for CP. The toxicity of our HFA dilutions in medium probably closely mimics studies using sodium fluoride because the cell medium buffers the free proton in our HFA dilutions.
Other challenges we encountered were related to refinement of the cell culture models for use in HTS. We found it necessary to modify the cell culture medium constituents for cells in experimentation, specifically hydrocortisone and antibiotics. We utilized a low level of hydrocortisone (0.5 &#181;g/mL) during exposure studies to suppress the occasional spike in cytokine production seen in naive SV40-HCEC. This low amount of hydrocortisone did not adversely affect the responses of the cells to toxicant and was below levels typically used to suppress cytokine production by cultured cells in response to stimulant36,37. The exact reasons why naive SV40-HCEC cells occasionally produce excess cytokines are not known, but it is possible that the cells are variably sensitive to the minor stressors that occur during cell passaging and plating. Many labs routinely include antibiotics in cell culture maintenance medium, but some antibiotics, tetracyclines in particular, have been shown to exhibit anti-inflammatory effects on cultured cells including corneal epithelial cells38. In general, our laboratory avoids the use of antibiotics whenever possible since these can potentially confound studies. We also investigated the phenotypic drift over multiple passages of our cells in culture. It is common for immortalized cells to undergo genetic and/or phenotypic drift over multiple passages, if not maintained in the exponential phase, if allowed to reach confluency, or if exposed to certain environmental stressors39,40,41. Therefore, it is critical during a high throughput screen that cell lines are properly maintained and that the screen is completed using cell passage numbers that maintain the known phenotypic response. Multi-well plate edge effects is the phenomenon that cells grown in the outer perimeter wells of multi-well plates often do not respond the same or with the same consistency as cells grown in interior wells42. There are statistical exercises, such as median polish, that can be utilized to minimize edge effects on a data set43. However, there is no statistical exercise that can eliminate edge effects on a particular target or control if it is always tested in an edge well, and varying the plate layout between replicates to move targets or controls off of edge wells is not logistically practical or cost effective. It is our opinion that the decision to include the use of edge wells in cell-based HTS assays should be made cautiously. We found it necessary to eliminate the use of cells grown in edge wells for controls and targets.
Our HTS cell model and exposure methodology for in vitro HF injury was used to successfully complete the primary siRNA screen of 3120 targets. SSMD was used for hit selection because it was proposed specifically to measure the magnitude of difference between a control and an siRNA27. Our results for cell viability show that there was a linear relationship in the dual-flashlight plot between SSMD and fold-change for virtually all targets. For this reason, we used the single criterion of SSMD for hit selection for this endpoint. The IL-8 data differed in that some targets had weak but consistent effects while others showed strong but inconsistent effects. Therefore, we used both fold-change and SSMD for hit selection criteria for this endpoint. The SSMD values used for hit selection for both cell viability and IL-8 data were chosen because cutoffs between 1 and 1.645 (or -1 and -1.65) achieve low false discovery and non-discovery rates44. There were some targets that were hits in both the cell viability and IL-8 data. In these cases, preference for inclusion in the deconvolution library was given to those targets that exerted their effects in the same direction of improving overall health (improved viability and decreased IL-8) or exacerbating injury (increased cell death and increased IL-8). Overall, we selected a total of 250 targets between the cell viability and IL-8 endpoints to make up the deconvolution library for HF injury. The primary screen for in vitro CP injury is in progress.
In summary, we have developed exposure and culture conditions suitable for the HTS study of ocular injury by HF and CP. Several variables in exposure and culture conditions were refined and optimized, and the models were validated to be suitable for HTS studies by Z&#39; factor analysis. We have further proven the utility of these models by completing the primary screen of an siRNA library in the HF model. There are many injuries and diseases that are of no or limited interest to the pharmaceutical or biotech industry, toxicant injury by CP and HF included, and the advent of benchtop robotics facilitates the HTS study of injuries and diseases in virtually any laboratory. High throughput genomic data sets can greatly contribute to the understanding of the roles that specific genes play in injury or disease which can help to more efficiently focus follow on in vitro or in vivo studies.

Toxicant-induced ocular injury is a true ocular emergency because chemicals have the potential to rapidly inflict significant tissue damage. Unfortunately, treatments for toxicant-induced corneal injury are only generally supportive as no specific therapeutics exist to treat these injuries. The current treatment strategy is non-specific and primarily includes topical therapeutic treatments such as lubricants, antibiotics, and cycloplegics followed by anti-inflammatories (e.g., steroids) once the cornea has re-epithelialized1,2. Despite the best current therapeutic treatment options available, long-term prognosis is generally poor due to progressive corneal clouding and neovascularization2,3.
Animal models have traditionally been used to investigate chemical toxicity and understand mechanisms of injury. However, animal studies are time consuming and expensive. There are also efforts to reduce animal testing. For example, REACH legislation (EC 1907/2006) in the European Union has provisions intended to reduce animal testing. The provisions include a requirement that companies share data in order to avoid animal testing and obtaining approval from the European Chemicals Agency prior to performing proposed tests on animals. Under the provisions of REACH, animal testing should be a last resort. There is also the European Cosmetics Regulation (EC 1223/2009) that phased out the testing of cosmetics in animals. When animal studies are conducted, they are guided by the principles of 3Rs (Refinement, Reduction, and Replacement), which provide a framework for performing more humane animal research, reducing the number of animals used, and using non-animal alternatives where possible. For these reasons, the field of toxicology has sought to adopt in vitro assays that can provide insight into molecular mechanisms of toxicity and can be done in higher throughput4. This is a functional toxicology approach where toxicants are defined by their function rather than solely by their chemistry. Taken a step further, functional toxicogenomics seek to understand the role(s) that specific genes play in the effects of toxicants5. With the application of siRNA technology, screens to investigate gene function in the molecular and cellular responses to toxicants can be done at high throughput. siRNA are double stranded RNA molecules that are 19-25 nucleotides long that take advantage of the post transcriptional gene silencing pathway present in all mammalian cells6. These are synthetically made and designed to target a specific gene. When introduced into a cell, the siRNA is processed and one strand, the guide strand, is loaded into the RNA-induced silencing complex (RISC). The siRNA directs the RISC to a complementary region in an mRNA molecule, and the RISC degrades the mRNA. This results in the reduction of expression of the specific gene. The resulting reduction of expression of the specific gene can then be studied in toxicant exposed cells to ascertain the function of that gene in the cellular response to the toxicant. Such an approach has been used to further understand the mechanisms of ricin susceptibility and the AHR-dependent induction of CYP1A17,8.
The Chemical Terrorism Risk Assessment (CTRA) list and the toxic industrial chemicals (TIC) listings have itemized select chemicals based on their toxicity and potential to be released during a terrorist, warfare, or industrial accident event9. We are applying an siRNA high throughput screening (HTS) toxicogenomic approach to the study of CTRA list toxicants, which have been identified to be at high risk of use in a terrorist incident. Traditional toxicology seeks to understand the adverse effects that chemicals have on living organisms; however, we have a further desire to understand the mechanisms of injury for the purpose of informing the development of therapeutics and therapeutic approaches, and possibly, to discover molecules which can be targeted for therapeutic development. This effort in some ways may be considered analogous to the use of high throughput siRNA screening and cell based assays in the drug discovery process10. A major difference would be that drug discovery typically seeks a singular target for therapeutic discovery whereas in our approach it is somewhat unlikely that there would be a singular target with high therapeutic value for the treatment of toxicant exposure. We anticipate that any effective treatment paradigm for toxicant exposure would require a multi-faceted approach to achieve high therapeutic value, and toxicogenomic data may vitally inform an effective treatment paradigm.
Benchtop automation brings high throughput methodology to laboratories outside the pharmaceutical or biotech industries. The in vitro studies at our institute have historically been traditional assays which are low throughput11,12,13. In the past few years, our laboratory has transitioned to the use of benchtop robotics to perform high throughput siRNA screening. Herein, we present the refinement of ocular cell models and the development of in vitro exposure methods for hydrogen fluoride (HF) and chloropicrin (CP) suitable for high throughput siRNA screening. Our goal is to identify molecules that regulate cellular injury in response to these toxicants. The targets of the siRNA library we selected include G protein-coupled receptors, protein kinases, proteases, phosphatases, ion channels, and other potentially druggable targets. HF and CP were selected for study by cross-referencing CTRA list agents with the ToxNet reports of industrial accidents to find those that present the greatest risk of ocular injury via vapor exposure9,14. CP (chemical formula Cl3CNO2, CAS number 76-06-2) was originally used as a tear gas in WWI15. It is currently used as an agricultural fumigant and functions as a nematicide, fungicide, and insecticide16. Hydrogen Fluoride (HF) is used in processes including alkylation in oil refineries and electrochemical fluorination of organic compounds17. HF (chemical formula HF, CAS number 62778-11-4) is a gas but in its aqueous form is hydrofluoric acid (HFA, CAS number 7664-39-3). Therefore, we elected to use HFA in our in cell exposure models. The SV40 large T antigen immortalized human corneal epithelial cell line SV40-HCEC was selected for study. Cell viability and the inflammatory marker IL-8 were selected as endpoints because targets that are involved in cellular injury should be reflected in the cell death and the inflammatory response. Specifically, if a target were to play a protective role in toxicant exposure, cell death and/or inflammatory cytokine production should increase when the target expression is inhibited by siRNA. The opposite would be true for targets that play a negative role. Also, chronic inflammation appears to play a role in cornea pathology after exposure, and intervention in cell death pathways may improve clinical outcome2,18.

<table border="0" cellpadding="0" cellspacing="0" style="width:879px;" width="880">
	<tbody>
		<tr height="21">
			<td height="21" style="height:21px;width:347px;">Bravo liquid handing platform</td>
			<td style="width:247px;">Agilent or equivalent</td>
			<td style="width:119px;">G5409A</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:347px;">Bravo plate shaker</td>
			<td style="width:247px;">Agilent or equivalent</td>
			<td style="width:119px;">Option 159</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:347px;">Bravo 96LT disposable tip head</td>
			<td style="width:247px;">Agilent or equivalent</td>
			<td style="width:119px;">Option 178</td>
			<td>96-channel large tip pipetting head unit</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:347px;">Bravo 96ST disposable tip head</td>
			<td style="width:247px;">Agilent or equivalent</td>
			<td style="width:119px;">Option 177</td>
			<td>96-channel small tip pipetting head unit</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:347px;">Bravo 384ST disposable tip head</td>
			<td style="width:247px;">Agilent or equivalent</td>
			<td style="width:119px;">Option 179</td>
			<td>384-channel small tip pipetting head unit</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:347px;">Bravo 96 250 &#956;L sterile barrier tips</td>
			<td style="width:247px;">Agilent or equivalent</td>
			<td style="width:119px;">19477-022</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:347px;">Bravo 384 30 &#956;L sterile barrier tips</td>
			<td style="width:247px;">Agilent or equivalent</td>
			<td style="width:119px;">19133-212</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:347px;">Bravo 384 70 &#956;L sterile barrier tips</td>
			<td style="width:247px;">Agilent or equivalent</td>
			<td style="width:119px;">19133-212</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:347px;">EnSpire multimode plate reader</td>
			<td style="width:247px;">Perkin Elmer or equivalent</td>
			<td style="width:119px;">2300-0000</td>
			<td>AlphaLISA assay detector with high power laser excitation</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:347px;">IL-8 (human) AlphaLISA Detection Kit&#160;</td>
			<td style="width:247px;">Perkin Elmer or equivalent</td>
			<td style="width:119px;">AL224F</td>
			<td>no-wash bead-based assay</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:347px;">ProxiPlate-384 Plus white 384-shallow well microplates</td>
			<td style="width:247px;">Perkin Elmer or equivalent</td>
			<td>6008359</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:347px;">Lipofectamine RNAiMAX</td>
			<td style="width:247px;">Invitrogen or equivalent</td>
			<td style="width:119px;">13778500</td>
			<td>Transfection reagent</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:347px;">Opti-MEM 1 Reduced Serum Medium</td>
			<td style="width:247px;">Invitrogen or equivalent</td>
			<td style="width:119px;">31985070</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:347px;">TrypLE Express</td>
			<td style="width:247px;">Gibco or equivalent</td>
			<td style="width:119px;">12605010</td>
			<td>Cell detachment solution</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:347px;">IncuCyte Zoom</td>
			<td style="width:247px;">Essen Instruments or equivalent</td>
			<td style="width:119px;">ESSEN BIOSCI 4473</td>
			<td>Incubator-housed automated microscope</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:347px;">Chloropicrin</td>
			<td style="width:247px;">Trinity Manufacturing or equivalent</td>
			<td style="width:119px;">N/A</td>
			<td>Acute toxicity and irritant</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:347px;">DMEM-F12 cell culture medium</td>
			<td style="width:247px;">Invitrogen or equivalent</td>
			<td>11330-057</td>
			<td>Contains HEPES</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:347px;">Fetal bovine serum</td>
			<td style="width:247px;">Invitrogen or equivalent</td>
			<td>1891471</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:347px;">Human epidermal growth factor (cell culture grade)</td>
			<td style="width:247px;">Invitrogen or equivalent</td>
			<td>E9644-.2MG</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:347px;">Recombinant human insulin (cell culture grade)</td>
			<td style="width:247px;">Invitrogen or equivalent</td>
			<td>12585-014</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:347px;">Penicillin-Streptomycin solution (cell culture grade)</td>
			<td style="width:247px;">Invitrogen or equivalent</td>
			<td>15140122</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:347px;">Hydrocortisone (cell culture grade)</td>
			<td style="width:247px;">Sigma or equivalent</td>
			<td>H0888-10G</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:347px;">Glucose&#160; (cell culture grade)</td>
			<td style="width:247px;">Sigma or equivalent</td>
			<td style="width:119px;">G7021</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:347px;">PBS&#160; (cell culture grade)</td>
			<td style="width:247px;">Sigma or equivalent</td>
			<td style="width:119px;">P5493</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:347px;">siRNA</td>
			<td style="width:247px;">Dharmacon or equivalent</td>
			<td style="width:119px;">various</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Thiazolyl blue tetrazolium bromide</td>
			<td style="width:247px;">Sigma or equivalent</td>
			<td style="width:119px;">M5655</td>
			<td>MTT assay substrate</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:347px;">siRNA buffer</td>
			<td style="width:247px;">Thermo or equivalent</td>
			<td style="width:119px;">B002000</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:347px;">96-well cell culture plates</td>
			<td style="width:247px;">Corning or equivalent</td>
			<td style="width:119px;">CLS3595</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:347px;">T150 cell culture flasks</td>
			<td style="width:247px;">Corning or equivalent</td>
			<td style="width:119px;">CLS430825</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:347px;">BSL-2 cell culture hood</td>
			<td style="width:247px;">Nuaire or equivalent</td>
			<td style="width:119px;">NU-540</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:347px;">300 mL robotic reservoirs</td>
			<td style="width:247px;">Thermo or equivalent</td>
			<td style="width:119px;">12-565-572&#160;</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:347px;">96 baffled automation reservoirs</td>
			<td style="width:247px;">Thermo or equivalent</td>
			<td style="width:119px;">1064-15-8</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:347px;">500 mL sterile disposable storage bottles</td>
			<td style="width:247px;">Corning or equivalent</td>
			<td style="width:119px;">CLS430282</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:347px;">Microplate heat sealer</td>
			<td style="width:247px;">Thermo or equivalent</td>
			<td style="width:119px;">AB-1443A</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:347px;">Microplate heat sealing foil</td>
			<td style="width:247px;">Thermo or equivalent</td>
			<td style="width:119px;">AB-0475</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:347px;">Cardamonin</td>
			<td style="width:247px;">Tocris or equivalent</td>
			<td style="width:119px;">2509</td>
			<td>Anti-inflammatory, used as positive control</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:347px;">SKF 86002&#160;</td>
			<td style="width:247px;">Tocris or equivalent</td>
			<td style="width:119px;">2008</td>
			<td>Anti-inflammatory, used as positive control</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:347px;">DMSO</td>
			<td style="width:247px;">Sigma or equivalent</td>
			<td style="width:119px;">D8418</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:347px;">48% hydrofluoric acid</td>
			<td style="width:247px;">Sigma or equivalent</td>
			<td style="width:119px;">339261</td>
			<td>Corrosive and acute toxicity</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:347px;">1000 &#956;L Single channel pipettors</td>
			<td style="width:247px;">Rainin or equivalent</td>
			<td style="width:119px;">17014382</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:347px;">200 &#956;L Single channel pipettors</td>
			<td style="width:247px;">Rainin or equivalent</td>
			<td style="width:119px;">17014391</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:347px;">20 &#956;L Single channel pipettors</td>
			<td style="width:247px;">Rainin or equivalent</td>
			<td style="width:119px;">17014392</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:347px;">1000 &#956;L 12-channel pipettors</td>
			<td style="width:247px;">Rainin or equivalent</td>
			<td style="width:119px;">17014497</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:347px;">200 &#956;L 12-channel pipettors</td>
			<td style="width:247px;">Rainin or equivalent</td>
			<td style="width:119px;">17013810</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:347px;">20 &#956;L 12-channel pipettors</td>
			<td style="width:247px;">Rainin or equivalent</td>
			<td style="width:119px;">17013808</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:347px;">Pipettor tips 1000 &#956;L</td>
			<td style="width:247px;">Rainin or equivalent</td>
			<td style="width:119px;">17002920</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:347px;">Pipettor tips 200 &#956;L</td>
			<td style="width:247px;">Rainin or equivalent</td>
			<td style="width:119px;">17014294</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:347px;">Pipettor tips 20 &#956;L</td>
			<td style="width:247px;">Rainin or equivalent</td>
			<td style="width:119px;">17002928</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:347px;">Chemical fume hood</td>
			<td style="width:247px;">Jamestown Metal Products</td>
			<td style="width:119px;">MHCO_229</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:347px;">384-well sample storage plates</td>
			<td style="width:247px;">Thermo or equivalent</td>
			<td style="width:119px;">262261</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:347px;">Sodium chloride</td>
			<td style="width:247px;">Sigma or equivalent</td>
			<td style="width:119px;">S6191</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:347px;">50 mL conical tubes</td>
			<td style="width:247px;">Thermo or equivalent</td>
			<td style="width:119px;">14-959-49A</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:347px;">Serological pipettes 50 mL</td>
			<td style="width:247px;">Corning or equivalent</td>
			<td style="width:119px;">07-200-576</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:347px;">Serological pipettes 25 mL</td>
			<td style="width:247px;">Corning or equivalent</td>
			<td style="width:119px;">07-200-575</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:347px;">Serological pipettes 10 mL</td>
			<td style="width:247px;">Corning or equivalent</td>
			<td style="width:119px;">07-200-574</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:347px;">Serological pipettes 5 mL</td>
			<td style="width:247px;">Corning or equivalent</td>
			<td style="width:119px;">07-200-573</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:347px;">SV40-HCEC immortalized human corneal epithelial cells</td>
			<td style="width:247px;">N/A</td>
			<td style="width:119px;">N/A</td>
			<td>These cells are not commercially available, but can be obtained from the investigators cited in the article</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:347px;">Sceptor Handheld Automated Cell Counter</td>
			<td style="width:247px;">Millipore or equivalent</td>
			<td style="width:119px;">PHCC20060</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:347px;">GeneTitan Multi-Channel (MC) Instrument</td>
			<td style="width:247px;">Affymetrix or equivalent</td>
			<td style="width:119px;">00-0372</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:347px;">Affymetrix 24- and 96-array plates</td>
			<td style="width:247px;">Affymetrix or equivalent</td>
			<td style="width:119px;">901257; 901434</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:347px;">Draegger tube HF</td>
			<td style="width:247px;">Draeger or equivalent</td>
			<td style="width:119px;">8103251</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:347px;">Draegger tube CP</td>
			<td style="width:247px;">Draeger or equivalent</td>
			<td style="width:119px;">8103421</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:347px;">Draegger pump</td>
			<td style="width:247px;">Draeger or equivalent</td>
			<td style="width:119px;">6400000</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:347px;">Clear Plate seals</td>
			<td style="width:247px;">Resesarch Products International or Equivalent</td>
			<td style="width:119px;">202502</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:347px;">Reagent reservoirs</td>
			<td style="width:247px;">VistaLab Technologies or equivalent</td>
			<td style="width:119px;">3054-1000</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:347px;">Xlfit</td>
			<td style="width:247px;">IDBS or equivalent</td>
			<td style="width:119px;">N/A</td>
			<td>Excel add-in used for automated curve fitting</td>
		</tr>
	</tbody>
</table>

high throughput sirna screening for chloropicrin and hydrogen fluoride-induced cornea epithelial cell injury

Toxicant-induced ocular injury is a true ocular emergency because chemicals have the potential to rapidly inflict significant tissue damage. Treatments for toxicant-induced corneal injury are generally supportive as no specific therapeutics exist to treat these injuries. In the efforts to develop treatments and therapeutics to care for exposure, it can be important to understand the molecular and cellular mechanisms of these injuries. We propose that utilization of high throughput small inhibitory RNA (siRNA) screening can be an important tool that could help to more rapidly elucidate the molecular mechanisms of chemical cornea epithelial injury. siRNA are double stranded RNA molecules that are 19-25 nucleotides long and utilize the post-transcriptional gene silencing pathway to degrade mRNA which have homology to the siRNA. The resulting reduction of expression of the specific gene can then be studied in toxicant exposed cells to ascertain the function of that gene in the cellular response to the toxicant. The development and validation of in vitro exposure models and methods for the high throughput screening (HTS) of hydrogen fluoride- (HF) and chloropicrin- (CP) induced ocular injury are presented in this article. Although we selected these two toxicants, our methods are applicable to the study of other toxicants with minor modifications to the toxicant exposure protocol. The SV40 large T antigen immortalized human corneal epithelial cell line SV40-HCEC was selected for study. Cell viability and IL-8 production were selected as endpoints in the screening protocol. Several challenges associated with the development of toxicant exposure and cell culture methods suitable for HTS studies are presented. The establishment of HTS models for these toxicants allows for further studies to better understand the mechanism of injury and to screen for potential therapeutics for chemical ocular injury.

Watch this Scientific Journal Video about High Throughput SiRNA Screening for Chloropicrin and Hydrogen Fluoride-Induced Cornea Epithelial Cell Injury at JoVE.com

High Throughput SiRNA Screening for Chloropicrin and Hydrogen Fluoride-Induced Cornea Epithelial Cell Injury

High throughput small inhibitory RNA screening is an important tool that could help to more rapidly elucidate the molecular mechanisms of chemical cornea epithelial injury. Herein, we present the development and validation of exposure models and methods for the high throughput screening of hydrogen fluoride- and chloropicrin-induced cornea epithelial injury.

Toxicant-induced ocular injury is a true ocular emergency because chemicals have the potential to rapidly inflict significant tissue damage. Treatments ...

high-throughput-sirna-screening-for-chloropicrin-hydrogen-fluoride

Nanyang Technological University

Research

JoVE Journal

Biology

5.8K Views.  US Army Medical Research Institute of Chemical Defense. High throughput small inhibitory RNA screening is an important tool that could help to more rapidly elucidate the molecular mechanisms of chemical cornea epithelial injury. Herein, we present the development and validation of exposure models and methods for the high throughput screening of hydrogen fluoride- and chloropicrin-induced cornea epithelial injury.

Video: High Throughput SiRNA Screening for Chloropicrin and Hydrogen Fluoride-Induced Cornea Epithelial Cell Injury

High-throughput Screening and Biosensing with Fluorescent C. elegans Strains

High-throughput screening (HTS) is a powerful approach for identifying chemical modulators of biological processes. However, many compounds identified in screens using cell culture models are often found to be toxic or pharmacologically inactive in vivo1-2. Screening in whole animal models can help avoid these pitfalls and streamline the path to drug development.
C. elegans is a multicellular model organism well suited for HTS. It is small (&lt;1 mm) and can be economically cultured and dispensed in liquids. C. elegans is also one of the most experimentally tractable animal models permitting rapid and detailed identification of drug mode-of-action3.
We describe a protocol for culturing and dispensing fluorescent strains of C. elegans for high-throughput screening of chemical libraries or detection of environmental contaminants that alter the expression of a specific gene. Large numbers of developmentally synchronized worms are grown in liquid culture, harvested, washed, and suspended at a defined density. Worms are then added to black, flat-bottomed 384-well plates using a peristaltic liquid dispenser. Small molecules from a chemical library or test samples (e.g., water, food, or soil) can be added to wells with worms. In vivo, real-time fluorescence intensity is measured with a fluorescence microplate reader. This method can be adapted to any inducible gene in C. elegans for which a suitable reporter is available. Many inducible stress and developmental transcriptional pathways are well defined in C. elegans and GFP transgenic reporter strains already exist for many of them4. When combined with the appropriate transgenic reporters, our method can be used to screen for pathway modulators or to develop robust biosensor assays for environmental contaminants. 
We demonstrate our C. elegans culture and dispensing protocol with an HTS assay we developed to monitor the C. elegans cap &#x2018;n&#x2019; collar transcription factor SKN-1. SKN-1 and its mammalian homologue Nrf2 activate cytoprotective genes during oxidative and xenobiotic stress5-10. Nrf2 protects mammals from numerous age-related disorders such as cancer, neurodegeneration, and chronic inflammation and has become a major chemotherapeutic target11-13.Our assay is based on a GFP transgenic reporter for the SKN-1 target gene gst-414, which encodes a glutathione-s transferase6. The gst-4 reporter is also a biosensor for xenobiotic and oxidative chemicals that activate SKN-1 and can be used to detect low levels of contaminants such as acrylamide and methyl-mercury15-16.

High-throughput Screening and Biosensing with Fluorescent C. elegans Strains

A procedure for liquid-based culturing and dispensing of C. elegans strains expressing fluorescent reporter proteins is described that does not require expensive sorting equipment. This approach can be applied to numerous inducible C. elegans genes for drug discovery or biosensing of contaminants.

High-throughput screening (HTS) is a powerful approach for identifying chemical modulators of biological processes.  However, many compounds identified in ...

High-throughput Yeast Plasmid Overexpression Screen

The budding yeast, Saccharomyces cerevisiae, is a powerful model system for defining fundamental mechanisms of many important cellular processes, including those with direct relevance to human disease. Because of its short generation time and well-characterized genome, a major experimental advantage of the yeast model system is the ability to perform genetic screens to identify genes and pathways that are involved in a given process. Over the last thirty years such genetic screens have been used to elucidate the cell cycle, secretory pathway, and many more highly conserved aspects of eukaryotic cell biology 1-5. In the last few years, several genomewide libraries of yeast strains and plasmids have been generated 6-10. These collections now allow for the systematic interrogation of gene function using gain- and loss-of-function approaches 11-16. Here we provide a detailed protocol for the use of a high-throughput yeast transformation protocol with a liquid handling robot to perform a plasmid overexpression screen, using an arrayed library of 5,500 yeast plasmids. We have been using these screens to identify genetic modifiers of toxicity associated with the accumulation of aggregation-prone human neurodegenerative disease proteins. The methods presented here are readily adaptable to the study of other cellular phenotypes of interest.

Here we describe a plasmid overexpression screen in Saccharomyces cerevisiae, using an arrayed plasmid library and a high-throughput yeast transformation protocol with a liquid handling robot.

The budding yeast, Saccharomyces cerevisiae, is a powerful model system for defining fundamental mechanisms of many important cellular processes, ...

High Throughput Screening of Fungal Endoglucanase Activity in Escherichia coli

Cellulase enzymes (endoglucanases, cellobiohydrolases, and &beta;-glucosidases) hydrolyze cellulose into component sugars, which in turn can be converted into fuel alcohols1. The potential for enzymatic hydrolysis of cellulosic biomass to provide renewable energy has intensified efforts to engineer cellulases for economical fuel production2. Of particular interest are fungal cellulases3-8, which are already being used industrially for foods and textiles processing.
Identifying active variants among a library of mutant cellulases is critical to the engineering process; active mutants can be further tested for improved properties and/or subjected to additional mutagenesis. Efficient engineering of fungal cellulases has been hampered by a lack of genetic tools for native organisms and by difficulties in expressing the enzymes in heterologous hosts. Recently, Morikawa and coworkers developed a method for expressing in E. coli the catalytic domains of endoglucanases from H. jecorina3,9, an important industrial fungus with the capacity to secrete cellulases in large quantities. Functional E. coli expression has also been reported for cellulases from other fungi, including Macrophomina phaseolina10 and Phanerochaete chrysosporium11-12. 
We present a method for high throughput screening of fungal endoglucanase activity in E. coli. (Fig 1) This method uses the common microbial dye Congo Red (CR) to visualize enzymatic degradation of carboxymethyl cellulose (CMC) by cells growing on solid medium. The activity assay requires inexpensive reagents, minimal manipulation, and gives unambiguous results as zones of degradation (&#x201C;halos&#x201D;) at the colony site. Although a quantitative measure of enzymatic activity cannot be determined by this method, we have found that halo size correlates with total enzymatic activity in the cell. Further characterization of individual positive clones will determine , relative protein fitness. 
Traditional bacterial whole cell CMC/CR activity assays13 involve pouring agar containing CMC onto colonies, which is subject to cross-contamination, or incubating cultures in CMC agar wells, which is less amenable to large-scale experimentation. Here we report an improved protocol that modifies existing wash methods14 for cellulase activity: cells grown on CMC agar plates are removed prior to CR staining. Our protocol significantly reduces cross-contamination and is highly scalable, allowing the rapid screening of thousands of clones. In addition to H. jecorina enzymes, we have expressed and screened endoglucanase variants from the Thermoascus aurantiacus and Penicillium decumbens (shown in Figure 2), suggesting that this protocol is applicable to enzymes from a range of organisms.

High Throughput Screening of Fungal Endoglucanase Activity in Escherichia coli

We describe a low cost, high throughput method to screen for fungal endoglucanase activity in E. coli. The method relies on a simple visual readout of substrate degradation, does not require enzyme purification, and is highly scalable. This allows for the rapid screening of large libraries of enzyme variants.

Cellulase enzymes (endoglucanases, cellobiohydrolases, and &beta;-glucosidases) hydrolyze cellulose into component sugars, which in turn can be converted ...

High-throughput Screening for Small-molecule Modulators of Inward Rectifier Potassium Channels

Specific members of the inward rectifier potassium (Kir) channel family are postulated drug targets for a variety of disorders, including hypertension, atrial fibrillation, and pain1,2. For the most part, however, progress toward understanding their therapeutic potential or even basic physiological functions has been slowed by the lack of good pharmacological tools. Indeed, the molecular pharmacology of the inward rectifier family has lagged far behind that of the S4 superfamily of voltage-gated potassium (Kv) channels, for which a number of nanomolar-affinity and highly selective peptide toxin modulators have been discovered3. The bee venom toxin tertiapin and its derivatives are potent inhibitors of Kir1.1 and Kir3 channels4,5, but peptides are of limited use therapeutically as well as experimentally due to their antigenic properties and poor bioavailability, metabolic stability and tissue penetrance. The development of potent and selective small-molecule probes with improved pharmacological properties will be a key to fully understanding the physiology and therapeutic potential of Kir channels.
The Molecular Libraries Probes Production Center Network (MLPCN) supported by the National Institutes of Health (NIH) Common Fund has created opportunities for academic scientists to initiate probe discovery campaigns for molecular targets and signaling pathways in need of better pharmacology6. The MLPCN provides researchers access to industry-scale screening centers and medicinal chemistry and informatics support to develop small-molecule probes to elucidate the function of genes and gene networks. The critical step in gaining entry to the MLPCN is the development of a robust target- or pathway-specific assay that is amenable for high-throughput screening (HTS).
Here, we describe how to develop a fluorescence-based thallium (Tl+) flux assay of Kir channel function for high-throughput compound screening7,8,9,10.The assay is based on the permeability of the K+ channel pore to the K+ congener Tl+. A commercially available fluorescent Tl+ reporter dye is used to detect transmembrane flux of Tl+ through the pore. There are at least three commercially available dyes that are suitable for Tl+ flux assays: BTC, FluoZin-2, and FluxOR7,8. This protocol describes assay development using FluoZin-2. Although originally developed and marketed as a zinc indicator, FluoZin-2 exhibits a robust and dose-dependent increase in fluorescence emission upon Tl+ binding. We began working with FluoZin-2 before FluxOR was available7,8 and have continued to do so9,10. However, the steps in assay development are essentially identical for all three dyes, and users should determine which dye is most appropriate for their specific needs. We also discuss the assay's performance benchmarks that must be reached to be considered for entry to the MLPCN. Since Tl+ readily permeates most K+ channels, the assay should be adaptable to most K+ channel targets.

Methods for developing and validating a quantitative fluorescence assay for measuring the activity of inward rectifier potassium (Kir) channels for high-throughput compound screening is presented.

Specific members of the inward rectifier potassium (Kir) channel family are postulated drug targets for a variety of disorders, including hypertension, ...

High-throughput Functional Screening using a Homemade Dual-glow Luciferase Assay

We present a rapid and inexpensive high-throughput screening protocol to identify transcriptional regulators of alpha-synuclein, a gene associated with Parkinson&#39;s disease. 293T cells are transiently transfected with plasmids from an arrayed ORF expression library, together with luciferase reporter plasmids, in a one-gene-per-well microplate format. Firefly luciferase activity is assayed after 48 hr to determine the effects of each library gene upon alpha-synuclein transcription, normalized to expression from an internal control construct (a hCMV promoter directing Renilla luciferase). This protocol is facilitated by a bench-top robot enclosed in a biosafety cabinet, which performs aseptic liquid handling in 96-well format. Our automated transfection protocol is readily adaptable to high-throughput lentiviral library production or other functional screening protocols requiring triple-transfections of large numbers of unique library plasmids in conjunction with a common set of helper plasmids. We also present an inexpensive and validated alternative to commercially-available, dual luciferase reagents which employs PTC124, EDTA, and pyrophosphate to suppress firefly luciferase activity prior to measurement of Renilla luciferase. Using these methods, we screened 7,670 human genes and identified 68 regulators of alpha-synuclein. This protocol is easily modifiable to target other genes of interest.

We present a rapid and inexpensive screening method for identifying transcriptional regulators using high-throughput robotic transfections and a homemade dual-glow luciferase assay. This protocol rapidly generates direct side-by-side functional data for thousands of genes and is easily modifiable to target any gene of interest.

We present a rapid and inexpensive high-throughput screening protocol to identify transcriptional regulators of alpha-synuclein, a gene associated with ...

Recovery of Adult Zebrafish Hearts for High-throughput Applications

Use of the zebrafish model system for studying development, regeneration, and disease is expanding toward use of adult hearts for cell dissociation and purification of RNA, DNA, and proteins. All of these applications demand the rapid recovery of significant numbers of zebrafish hearts to avoid gene regulatory, metabolic, and other changes that begin after death. Adult zebrafish hearts are also required for studying heart structure for a variety of mutants and for studying heart regeneration. However, the traditional zebrafish heart dissection is slow and difficult and requires specialized tools, making large-scale dissection of adult zebrafish hearts tedious. Traditional methods also harbor the risk of damaging the heart during the dissection. Here, we describe a method for dissection of adult zebrafish hearts that is fast, reproducible, and preserves heart architecture. Furthermore, this method does not require specialized tools, is painless for the zebrafish, can be performed on fresh or fixed specimens, and can be performed on zebrafish as young as one month old. The approach described expands the use of adult zebrafish for cardiovascular research.

Use of zebrafish for cardiovascular research is expanding towards research on adult hearts. For these applications, quick and simple isolation of cardiac tissues is key to avoid post-mortem changes and to obtain an adequate number of samples. Here, we describe a fast and reproducible method for dissecting adult zebrafish hearts.

Use of the zebrafish model system for studying development, regeneration, and disease is expanding toward use of adult hearts for cell dissociation and ...

High-throughput Screening for Chemical Modulators of Post-transcriptionally Regulated Genes

Both transcriptional and post-transcriptional regulation have a profound impact on genes expression. However, commonly adopted cell-based screening assays focus on transcriptional regulation, being essentially aimed at the identification of promoter-targeting molecules. As a result, post-transcriptional mechanisms are largely uncovered by gene expression targeted drug development. Here we describe a cell-based assay aimed at investigating the role of the 3&#39; untranslated region (3&#8217; UTR) in the modulation of the fate of its mRNA, and at identifying compounds able to modify it. The assay is based on the use of a luciferase reporter construct containing the 3&#8217; UTR of a gene of interest stably integrated into a disease-relevant cell line. The protocol is divided into two parts, with the initial focus on the primary screening aimed at the identification of molecules affecting luciferase activity after 24 hr of treatment. The second part of the protocol describes the counter-screening necessary to discriminate compounds modulating luciferase activity specifically through the 3&#8217; UTR. In addition to the detailed protocol and representative results, we provide important considerations about the assay development and the validation of the hit(s) on the endogenous target. The described cell-based reporter gene assay will allow scientists to identify molecules modulating protein levels via post-transcriptional mechanisms dependent on a 3&#8217; UTR.

Here we describe a cell-based reporter gene assay as a valuable tool to screen chemical libraries for compounds modulating post-transcriptional control mechanisms exerted through 3&#8217; UTR.

Both transcriptional and post-transcriptional regulation have a profound impact on genes expression. However, commonly adopted cell-based screening assays ...

Identification of Kinase-substrate Pairs Using High Throughput Screening

We have developed a screening platform to identify dedicated human protein kinases for phosphorylated substrates which can be used to elucidate novel signal transduction pathways. Our approach features the use of a library of purified GST-tagged human protein kinases and a recombinant protein substrate of interest. We have used this technology to identify MAP/microtubule affinity-regulating kinase 2 (MARK2) as the kinase for a glucose-regulated site on CREB-Regulated Transcriptional Coactivator 2 (CRTC2), a protein required for beta cell proliferation, as well as the Axl family of tyrosine kinases as regulators of cell metastasis by phosphorylation of the adaptor protein ELMO. We describe this technology and discuss how it can help to establish a comprehensive map of how cells respond to environmental stimuli.

Protein phosphorylation is a central feature of how cells interpret and respond to information in their extracellular milieu. Here, we present a high throughput screening protocol using kinases purified from mammalian cells to rapidly identify kinases that phosphorylate a substrate(s) of interest.


We have developed a screening platform to identify dedicated human protein kinases for phosphorylated substrates which can be used to elucidate novel ...

Multi-enzyme Screening Using a High-throughput Genetic Enzyme Screening System

The recent development of a high-throughput single-cell assay technique enables the screening of novel enzymes based on functional activities from a large-scale metagenomic library1. We previously proposed a genetic enzyme screening system (GESS) that uses dimethylphenol regulator activated by phenol or p-nitrophenol. Since a vast amount of natural enzymatic reactions produce these phenolic compounds from phenol deriving substrates, this single genetic screening system can be theoretically applied to screen over 200 different enzymes in the BRENDA database. Despite the general applicability of GESS, applying the screening process requires a specific procedure to reach the maximum flow cytometry signals. Here, we detail the developed screening process, which includes metagenome preprocessing with GESS and the operation of a flow cytometry sorter. Three different phenolic substrates (p-nitrophenyl acetate, p-nitrophenyl-&#946;-D-cellobioside, and phenyl phosphate) with GESS were used to screen and to identify three different enzymes (lipase, cellulase, and alkaline phosphatase), respectively. The selected metagenomic enzyme activities were confirmed only with the flow cytometry but DNA sequencing and diverse in vitro analysis can be used for further gene identification.

This work presents a method of high-throughput screening using a universal genetic enzyme screening system that can be theoretically applied to over 200 enzymes. Here, the single screening system identifies three different enzymes (lipase, cellulase, and alkaline phosphatase) by simply changing the substrate used (p-nitrophenyl acetate, p-nitrophenyl-&#946;-D-cellobioside, and phenyl phosphate).

The recent development of a high-throughput single-cell assay technique enables the screening of novel enzymes based on functional activities from a ...

High-throughput Screening for Protein-based Inheritance in S. cerevisiae

The encoding of biological information that is accessible to future generations is generally achieved via changes to the DNA sequence. Long-lived inheritance encoded in protein conformation (rather than sequence) has long been viewed as paradigm-shifting but rare. The best characterized examples of such epigenetic elements are prions, which possess a self-assembling behavior that can drive the heritable manifestation of new phenotypes. Many archetypal prions display a striking N/Q-rich sequence bias and assemble into an amyloid fold. These unusual features have informed most screening efforts to identify new prion proteins. However, at least three known prions (including the founding prion, PrPSc) do not harbor these biochemical characteristics. We therefore developed an alternative method to probe the scope of protein-based inheritance based on a property of mass action: the transient overexpression of prion proteins increases the frequency at which they acquire a self-templating conformation. This paper describes a method for analyzing the capacity of the yeast ORFeome to elicit protein-based inheritance. Using this strategy, we previously found that &gt;1% of yeast proteins could fuel the emergence of biological traits that were long-lived, stable, and arose more frequently than genetic mutation. This approach can be employed in high throughput across entire ORFeomes or as a targeted screening paradigm for specific genetic networks or environmental stimuli. Just as forward genetic screens define numerous developmental and signaling pathways, these techniques provide a methodology to investigate the influence of protein-based inheritance in biological processes.

High-throughput Screening for Protein-based Inheritance in S. cerevisiae

This protocol describes a high-throughput methodology to functionally screen for protein-based inheritance in S. cerevisiae.

High Throughput SiRNA Screening for Chloropicrin and Hydrogen Fluoride-Induced Cornea Epithelial Cell Injury

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High-throughput Screening and Biosensing with Fluorescent C. elegans Strains

High-throughput Yeast Plasmid Overexpression Screen

High Throughput Screening of Fungal Endoglucanase Activity in Escherichia coli

High-throughput Screening for Small-molecule Modulators of Inward Rectifier Potassium Channels

High-throughput Functional Screening using a Homemade Dual-glow Luciferase Assay

Recovery of Adult Zebrafish Hearts for High-throughput Applications

High-throughput Screening for Chemical Modulators of Post-transcriptionally Regulated Genes

Identification of Kinase-substrate Pairs Using High Throughput Screening

Multi-enzyme Screening Using a High-throughput Genetic Enzyme Screening System

High-throughput Screening for Protein-based Inheritance in S. cerevisiae