1) Zebrafish Egg Collection
<ol>
	<li>On the afternoon prior to the day of the chemical screen, set up 10 to 20 zebrafish breeding tanks. Fill each tank with water from the aquaculture system. Using a fish net, transfer one adult male and one to two adult females to inner container in each breeding tank. Separate the male and female fish from each other with a divider. Label the cages and put a lid over them.</li>
	<li>On the morning of the screen, remove the dividers from breeding tanks and allow zebrafish to mate. Over the course of next 1 hour, allow fertilized eggs to fall through grid at the bottom of each inner container.</li>
	<li>After 1 hour, return adult zebrafish back to permanent storage tanks, remove the inner container and collect the eggs by straining the water in each breeding tank through a plastic tea strainer. </li>
	<li>Invert the strainer over a Petri dish and rinse the strainer gently to flush the eggs into the Petri dish by using a wash bottle containing the E3 medium. </li>
	<li>All unfertilized eggs, which appear opaque, should be removed using a disposable plastic pipette. Each mating cross should yield approximately 200 embryos.</li>
</ol>
2) Arraying Embryos in 96-well Plates
<ol>
	<li>Transfer about 5 embryos in E3 medium into each well of a 96-well plate by using a glass Pasteur pipette.</li>
	<li> Once embryos are arrayed onto the 96-well plate, remove as much of the E3 medium as possible out of the wells using a 12-channel (30 - 300 &mu;L) pipette, taking care not to puncture the embryo. Using the 12-channel pipette, deliver 250 &mu;L of E3 medium containing 0.5&mu;g/ml kanamycin to each well as quickly as possible so as not to allow embryos to dry up.</li>
	<li> Put the 96-well plates into 28.5&deg;C incubator until they reach the desired stage when the compounds to be added.</li>
</ol>
3) Transfer of Small Molecule Library
While compound transfer can be automated with robotic transfer methods, we will describe the manual transfer method.
<ol>
	<li>Small molecule libraries are typically supplied in a 96-well format, with each compound stored in DMSO as a 10 mM stock. About 60 minutes before the embryos reach the stage when the compounds are to be added, thaw a desired number of 96-well plates containing aliquots of small molecules (source plate). Take note of the serial or other identification number of the source plates. To minimize condensation on the plates, thawing can occur in a desiccation chamber containing Drierite (W.A. HAMMOND DRIERITE CO, Xenia, OH).</li>
	<li>Briefly spin down the plates in a tabletop centrifuge equipped with multi-well plate adaptor.</li>
	<li>Remove the aluminum sealing tape from source plate. Using a 12-channel pipette, dilute the compounds in the source plate to the concentration of 0.5 mM (for example, if starting with 250 nL aliquots of 10mM stock, add 4.75 &mu;L of DMSO to each well). </li>
	<li>When the embryos in the 96-well plate (recipient plate) reach the desired stage, use a 12-channel (2-20 &mu;L) pipette to transfer 2.5&mu;L of compounds (0.5mM) from the source plates into the recipient plates containing the embryos.</li>
	<li>Record the identification number of the source plates on the recipient embryo plates. Cover the recipient plates now containing the embryos and compounds with lids, gently mix the plates by gently swirling, and place them in a 28.5&deg;C incubator.</li>
	<li>Cover each source plate containing unused small molecules (0.5 mM) with an aluminum sealing tape and place in a -80&deg;C freezer for long-term storage.</li>
</ol>
4) Screening for Effects of Small Molecules by Visual Inspection of Phenotypes
<ol>
	<li>Prior to performing the screen, formulate a specific criterion for what would constitute a "hit".</li>
	<li>At desired times in development, remove the 96-well plates containing compound-treated embryos from incubator and examine each well under a stereomicroscope. For better visualization of subtle changes, such as changes in circulatory pattern, a phase-contrast inverted microscope can be used. Fluorescent microscopy can be used to examine perturbation of expression of GFP or DsRed proteins under a tissue-specific promoter.</li>
	<li>Quickly scan the 96-well plates for any well in which at least 3 out of 5 embryos exhibit the prescribed "hit" phenotype. Record the identity of the plate and the well location of each potential hit. </li>
	<li>Reconfirm a potential hit by retesting the effects of the compound at several doses (1 uM, 5 uM, 10 &mu;M and 50 &mu;M). For each dose, 10 embryos are tested in 0.5 mL of E3 media in a 48-well plate format. The timing of compound addition for retesting should be identical to that of the original screening. A hit is confirmed when the elicited phenotype is reproduced on retesting of the compound</li>
	<li>Identify the hit compound from the database of small molecules in the chemical library.</li>
</ol>

<ol>
	<li>Bayliss, P. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Chemical+modulation+of+receptor+signaling+inhibits+regenerative+angiogenesis+in+adult+zebrafish.">Chemical modulation of receptor signaling inhibits regenerative angiogenesis in adult zebrafish.</a> Nature chemical biology. 2, 265-273 (2006).</li><li>Burns, C. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=High-throughput+assay+for+small+molecules+that+modulate+zebrafish+embryonic+heart+rate.">High-throughput assay for small molecules that modulate zebrafish embryonic heart rate.</a> Nature chemical biology. 1, 263-264 (2005).</li><li>Hao, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=In+vivo+structure-activity+relationship+study+of+dorsomorphin+analogues+identifies+selective+VEGF+and+BMP+inhibitors.">In vivo structure-activity relationship study of dorsomorphin analogues identifies selective VEGF and BMP inhibitors.</a> ACS chemical biology. 5, 245-253 (2010).</li><li>Hong, C. C., Peterson, Q. P., Hong, J. Y., Peterson, R. T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Artery/vein+specification+is+governed+by+opposing+phosphatidylinositol-3+kinase+and+MAP+kinase/ERK+signaling.">Artery/vein specification is governed by opposing phosphatidylinositol-3 kinase and MAP kinase/ERK signaling.</a> Curr Biol. 16, 1366-1372 (2006).</li><li>Milan, D. J., Peterson, T. A., Ruskin, J. N., Peterson, R. T., MacRae, C. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Drugs+that+induce+repolarization+abnormalities+cause+bradycardia+in+zebrafish.">Drugs that induce repolarization abnormalities cause bradycardia in zebrafish.</a> Circulation. 107, 1355-1358 (2003).</li><li>Peterson, R. T., Link, B. A., Dowling, J. E., Schreiber, S. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Small+molecule+developmental+screens+reveal+the+logic+and+timing+of+vertebrate+development.">Small molecule developmental screens reveal the logic and timing of vertebrate development.</a> Proceedings of the National Academy of Sciences of the United States of America. 97, 12965-12969 (2000).</li><li>Yu, P. B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Dorsomorphin+inhibits+BMP+signals+required+for+embryogenesis+and+iron+metabolism.">Dorsomorphin inhibits BMP signals required for embryogenesis and iron metabolism.</a> Nature chemical biology. 4, 33-41 (2008).</li><li>Zon, L. I., Peterson, R. T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=In+vivo+drug+discovery+in+the+zebrafish.">In vivo drug discovery in the zebrafish.</a> Nature reviews. 4, 35-44 (2005).</li><li>Stern, H. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Small+molecules+that+delay+S+phase+suppress+a+zebrafish+bmyb+mutant.">Small molecules that delay S phase suppress a zebrafish bmyb mutant.</a> Nature chemical biology. 1, 366-370 (2005).</li><li>Peterson, R. T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Chemical+suppression+of+a+genetic+mutation+in+a+zebrafish+model+of+aortic+coarctation.">Chemical suppression of a genetic mutation in a zebrafish model of aortic coarctation.</a> Nature biotechnology. 22, 595-599 (2004).</li></ol>

No conflicts of interest declared.

When planning a zebrafish-based chemical screen, particular attention must be paid to the robustness of the phenotype under consideration and the background rate of such phenotype. This is particularly important for screens for chemical suppressors of an induced phenotype. For example, for a phenotype caused by heat-shock induction of a transgene, the condition that induces the phenotype reproducibly must be precisely mapped out prior to initiating the screen to avoid unacceptably high false positive rates. With care...

<ol>
	<li>Minimum of 20 pairs of adult zebrafish of desired genotype.</li>
	<li>Fish nets, Breeding tanks, with removable inner container and dividers (Aquatic Habitats).</li>
	<li>Petri dishes (10 cm).</li>
	<li>Plastic tea strainer.</li>
	<li>Wash bottle containg embryo water.</li>
	<li>Disposable polyethylene transfer pipettes.</li>
	<li>Polystyrene 96-well round-bottom assay plates (Corning COSTAR; Lowell, MA).</li>
	<li>Glass Pasteur pipette (Fisher Scientific).</li>
	<li>Manual pipette pump, 10 mL (Bel-Art Products, Pequannock, NJ).</li>
	<li>E3 embryo medium: 5 mM NaCl, 0.17 mM KCl, 0.33 mM CaCl2 , 0.33 mM MgSO4 , containing 0.003% PTU (phenylthio-carbamide, Sigma; St. Louis, MO). PTU can be prepared as a 10x solution by dissolving 0.3-g PTU in 1 L of E3 embryo media. Solutions containing PTU should be protected from light by covering with aluminum foil.</li>
	<li>12-channel pipettes, 2-20 &mu;L (Eppendorf).</li>
	<li>12-channel pipettes, 3-300 &mu;L (Eppendorf).</li>
	<li>Disposable polystyrene pipette basin, 50 mL (Fisher Scientific).</li>
	<li>Small molecule library of structurally diverse compounds arrayed in a 96-wll format at 10 mM stock in DMSO. Each master plate is aliquoted into 96-well polypropylene storage plates (Corning), and stored at -80&deg;C until use.</li>
	<li>Aluminum sealing tape for 96-well plates (Nunc, Rochester, NY).</li>
	<li>DMSO (Sigma, St. Louis, MO).</li>
	<li>Basic incubator, 28.5&deg;C (Fisher Scientific).</li>
	<li>Stereomicroscope with transmitted light base (Leica Microsystems, Bannockburn, IL).</li>
</ol>

large scale zebrafish-based in vivo small molecule screen

Given their small embryo size, rapid development, transparency, fecundity, and numerous molecular, morphological and physiological similarities to mammals, zebrafish has emerged as a powerful in vivo platform for phenotype-based drug screens and chemical genetic analysis. Here, we demonstrate a simple, practical method for large-scale screening of small molecules using zebrafish embryos.

Watch this Scientific Journal Video about Large Scale Zebrafish-Based In vivo Small Molecule Screen at JoVE.com

Large Scale Zebrafish-Based In vivo Small Molecule Screen

Zebrafish has emerged as a powerful in vivo platform for phenotype-based drug screens and chemical genetic analysis. Here, we demonstrate a simple, practical method for large-scale screening of small molecules using zebrafish embryos.

Large Scale Zebrafish-Based In vivo Small Molecule Screen

Given their small embryo size, rapid development, transparency, fecundity, and numerous molecular, morphological and physiological similarities to ...

large-scale-zebrafish-based-in-vivo-small-molecule-screen

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13.4K Views.  Vanderbilt University School of Medicine. Zebrafish has emerged as a powerful in vivo platform for phenotype-based drug screens and chemical genetic analysis. Here, we demonstrate a simple, practical method for large-scale screening of small molecules using zebrafish embryos.

Video: Large Scale Zebrafish-Based In vivo Small Molecule Screen

Large-Scale Screens of Metagenomic Libraries

Metagenomic libraries archive large fragments of contiguous genomic sequences from microorganisms without requiring prior cultivation. Generating a streamlined procedure for creating and screening metagenomic libraries is therefore useful for efficient high-throughput investigations into the genetic and metabolic properties of uncultured microbial assemblages. Here, key protocols are presented on video, which we propose is the most useful format for accurately describing a long process that alternately depends on robotic instrumentation and (human) manual interventions. First, we employed robotics to spot library clones onto high-density macroarray membranes, each of which can contain duplicate colonies from twenty-four 384-well library plates. Automation is essential for this procedure not only for accuracy and speed, but also due to the miniaturization of scale required to fit the large number of library clones into highly dense spatial arrangements. Once generated, we next demonstrated how the macroarray membranes can be screened for genes of interest using modified versions of standard protocols for probe labeling, membrane hybridization, and signal detection. We complemented the visual demonstration of these procedures with detailed written descriptions of the steps involved and the materials required, all of which are available online alongside the video.

Metagenomic libraries archive large fragments of contiguous genomic sequences from microorganisms without requiring prior cultivation.  Generating a ...

Batch Immunostaining for Large-Scale Protein Detection in the Whole Monkey Brain

Immunohistochemistry (IHC) is one of the most widely used laboratory techniques for the detection of target proteins in situ. Questions concerning the expression pattern of a target protein across the entire brain are relatively easy to answer when using IHC in small brains, such as those of rodents. However, answering the same questions in large and convoluted brains, such as those of primates presents a number of challenges. Here we present a systematic approach for immunodetection of target proteins in an adult monkey brain. This approach relies on the tissue embedding and sectioning methodology of NeuroScience Associates (NSA) as well as tools developed specifically for batch-staining of free-floating sections. It results in uniform staining of a set of sections which, at a particular interval, represents the entire brain. The resulting stained sections can be subjected to a wide variety of analytical procedures in order to measure protein levels, the population of neurons expressing a certain protein.

Large-scale immunodetection of target proteins across the entire primate brain is possible by employing novel tissue embedding and sectioning methods combined with the use of creative apparatus for batch staining of multiple free-floating sections at a given time.

Immunohistochemistry (IHC) is one of the most widely used laboratory techniques for the detection of target proteins in situ. Questions concerning the ...

Isolation and Large Scale Expansion of Adult Human Endothelial Colony Forming Progenitor Cells

This paper introduces a novel recovery strategy for endothelial colony forming progenitor cells (ECFCs) from heparinized but otherwise unmanipulated adult human peripheral blood within a mean of 12 days. After large scale expansion &gt;1x108 ECFCs can be obtained for further tests. Advantageously by using pHPL the contact of human cells with bovine serum antigens can be excluded. By flow cytometry and immunohistochemistry the isolated cells can be characterized as ECFC and their in vitro functionality to form vascular like structures can be tested in a matrigel assay. Further these cells can be subcutaneously injected in a mouse model to form functional, perfused vessels in vivo. After long term expansion and cryopreservation proliferation, function and genomic stability appear to be preserved. 3,4
This animal-protein free isolation and expansion method is easily applicable to generate a large quantity of ECFCs.

Endothelial colony forming progenitor cells (ECFCs) are a promising tool to study vascular homeostasis and repair.1,2 This paper introduces a novel animal-serum free method for isolation and expansion of ECFC from heparinised adult human peripheral blood with pooled human platelet lysate (pHPL) diminishing the risk of anti-bovine immunisation.

This paper introduces a novel recovery strategy for endothelial colony forming progenitor cells (ECFCs) from heparinized but otherwise unmanipulated adult ...

Efficient Derivation of Human Cardiac Precursors and Cardiomyocytes from Pluripotent Human Embryonic Stem Cells with Small Molecule Induction

To date, the lack of a suitable human cardiac cell source has been the major setback in regenerating the human myocardium, either by cell-based transplantation or by cardiac tissue engineering1-3. Cardiomyocytes become terminally-differentiated soon after birth and lose their ability to proliferate. There is no evidence that stem/progenitor cells derived from other sources, such as the bone marrow or the cord blood, are able to give rise to the contractile heart muscle cells following transplantation into the heart1-3. The need to regenerate or repair the damaged heart muscle has not been met by adult stem cell therapy, either endogenous or via cell delivery1-3. The genetically stable human embryonic stem cells (hESCs) have unlimited expansion ability and unrestricted plasticity, proffering a pluripotent reservoir for in vitro derivation of large supplies of human somatic cells that are restricted to the lineage in need of repair and regeneration4,5. Due to the prevalence of cardiovascular disease worldwide and acute shortage of donor organs, there is intense interest in developing hESC-based therapies as an alternative approach. However, how to channel the wide differentiation potential of pluripotent hESCs efficiently and predictably to a desired phenotype has been a major challenge for both developmental study and clinical translation. Conventional approaches rely on multi-lineage inclination of pluripotent cells through spontaneous germ layer differentiation, resulting in inefficient and uncontrollable lineage-commitment that is often followed by phenotypic heterogeneity and instability, hence, a high risk of tumorigenicity6-8 (see a schematic in Fig. 1A). In addition, undefined foreign/animal biological supplements and/or feeders that have typically been used for the isolation, expansion, and differentiation of hESCs may make direct use of such cell-specialized grafts in patients problematic9-11. To overcome these obstacles, we have resolved the elements of a defined culture system necessary and sufficient for sustaining the epiblast pluripotence of hESCs, serving as a platform for de novo derivation of clinically-suitable hESCs and effectively directing such hESCs uniformly towards clinically-relevant lineages by small molecules12 (see a schematic in Fig. 1B). After screening a variety of small molecules and growth factors, we found that such defined conditions rendered nicotinamide (NAM) sufficient to induce the specification of cardiomesoderm direct from pluripotent hESCs that further progressed to cardioblasts that generated human beating cardiomyocytes with high efficiency (Fig. 2). We defined conditions for induction of cardioblasts direct from pluripotent hESCs without an intervening multi-lineage embryoid body stage, enabling well-controlled efficient derivation of a large supply of human cardiac cells across the spectrum of developmental stages for cell-based therapeutics.

We have established a protocol for induction of cardioblasts direct from pluripotent human embryonic stem cells maintained under defined conditions with small molecules, which enables derivation of a large supply of human cardiac progenitors and functional cardiomyocytes for cardiovascular repair.

To date, the lack of a suitable human cardiac cell source has been the major setback in regenerating the human myocardium, either by cell-based ...

Small-scale Nuclear Extracts for Functional Assays of Gene-expression Machineries

A great deal of progress in understanding gene expression has been made using in vitro systems. For most studies, functional assays are carried out using extracts that are prepared in bulk from 10-50 or more liters of cells grown in suspension. However, these large-scale preparations are not amenable to rapidly testing in vitro effects that result from a variety of in vivo cellular treatments or conditions. This journal video article shows a method for preparing functional small-scale nuclear extracts, using HeLa cells as an example. This method is carried out using as few as three 150 mm plates of cells grown as adherent monolayers. To illustrate the efficiency of the small-scale extracts, we show that they are as active as bulk nuclear extracts for coupled RNA Polymerase II transcription/splicing reactions. To demonstrate the utility of the extract protocol, we show that splicing is abolished in extracts prepared from HeLa cells treated with the splicing inhibitor drug E7107. The small-scale protocol should be generally applicable to any process or cell type that can be investigated in vitro using cellular extracts. These include patient cells that are only available in limited quantities or cells exposed to numerous agents such as drugs, DNA damaging agents, RNAi, or transfection, which require the use of small cell populations. In addition, small amounts of freshly grown cells are convenient and/or required for some applications.

A protocol for preparation of robust, small-scale HeLa nuclear extracts is described. This protocol is valuable for assays that require use of small populations of cells, such as cells treated with drugs or RNAi. The method should be applicable to a wide variety of gene expression assays and other cell types, including patient cells.

A great deal of progress in understanding gene expression has been made using in vitro systems.  For most studies, functional assays are carried out using ...

Infinium Assay for Large-scale SNP Genotyping Applications

Genotyping variants in the human genome has proven to be an efficient method to identify genetic associations with phenotypes. The distribution of variants within families or populations can facilitate identification of the genetic factors of disease. Illumina&#39;s panel of genotyping BeadChips allows investigators to genotype thousands or millions of single nucleotide polymorphisms (SNPs) or to analyze other genomic variants, such as copy number, across a large number of DNA samples. These SNPs can be spread throughout the genome or targeted in specific regions in order to maximize potential discovery. The Infinium assay has been optimized to yield high-quality, accurate results quickly. With proper setup, a single technician can process from a few hundred to over a thousand DNA samples per week, depending on the type of array. This assay guides users through every step, starting with genomic DNA and ending with the scanning of the array. Using propriety reagents, samples are amplified, fragmented, precipitated, resuspended, hybridized to the chip, extended by a single base, stained, and scanned on either an iScan or Hi Scan high-resolution optical imaging system. One overnight step is required to amplify the DNA. The DNA is denatured and isothermally amplified by whole-genome amplification; therefore, no PCR is required. Samples are hybridized to the arrays during a second overnight step. By the third day, the samples are ready to be scanned and analyzed. Amplified DNA may be stockpiled in large quantities, allowing bead arrays to be processed every day of the week, thereby maximizing throughput.

A protocol is described that uses Illumina&#39;s Infinium assays to perform large-scale genotyping. These assays can reliably genotype millions of SNPs across hundreds of individual DNA samples in three days. Once generated, these genotypes can be used to check for associations with a variety of different diseases or phenotypes.

Genotyping variants in the human genome has proven to be an efficient method to identify genetic associations with phenotypes. The distribution of ...

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 ...

A Manual Small Molecule Screen Approaching High-throughput Using Zebrafish Embryos

Zebrafish have become a widely used model organism to investigate the mechanisms that underlie developmental biology and to study human disease pathology due to their considerable degree of genetic conservation with humans. Chemical genetics entails testing the effect that small molecules have on a biological process and is becoming a popular translational research method to identify therapeutic compounds. Zebrafish are specifically appealing to use for chemical genetics because of their ability to produce large clutches of transparent embryos, which are externally fertilized. Furthermore, zebrafish embryos can be easily drug treated by the simple addition of a compound to the embryo media. Using whole-mount in situ hybridization (WISH), mRNA expression can be clearly visualized within zebrafish embryos. Together, using chemical genetics and WISH, the zebrafish becomes a potent whole organism context in which to determine the cellular and physiological effects of small molecules. Innovative advances have been made in technologies that utilize machine-based screening procedures, however for many labs such options are not accessible or remain cost-prohibitive. The protocol described here explains how to execute a manual high-throughput chemical genetic screen that requires basic resources and can be accomplished by a single individual or small team in an efficient period of time. Thus, this protocol provides a feasible strategy that can be implemented by research groups to perform chemical genetics in zebrafish, which can be useful for gaining fundamental insights into developmental processes, disease mechanisms, and to identify novel compounds and signaling pathways that have medically relevant applications.

The zebrafish is an excellent experimental organism to study vertebrate developmental processes and model human disease. Here, we describe a protocol on how to perform a manual high-throughput chemical screen in zebrafish embryos with a whole-mount in situ hybridization (WISH) read-out.

Zebrafish have become a widely used model organism to investigate the mechanisms that underlie developmental biology and to study human disease pathology ...

Identification of Novel Regulators of Plant Transpiration by Large-Scale Thermal Imaging Screening in Helianthus Annuus

Plant adaptation to biotic and abiotic stresses is governed by a variety of factors, among which the regulation of stomatal aperture in response to water deficit or pathogens plays a crucial role. Identifying small molecules that regulate stomatal movement can therefore contribute to understanding the physiological basis by which plants adapt to their environment. Large-scale screening approaches that have been used to identify regulators of stomatal movement have potential limitations: some rely heavily on the abscisic acid (ABA) hormone signaling pathway, therefore excluding ABA-independent mechanisms, while others rely on the observation of indirect, long-term physiological effects such as plant growth and development. The screening method presented here allows the large-scale treatment of plants with a library of chemicals coupled with a direct quantification of their transpiration by thermal imaging. Since evaporation of water through transpiration results in leaf surface cooling, thermal imaging provides a non-invasive approach to investigate changes in stomatal conductance over time. In this protocol, Helianthus annuus seedlings are grown hydroponically and then treated by root feeding, in which the primary root is cut and dipped into the chemical being tested. Thermal imaging followed by statistical analysis of cotyledonary temperature changes over time allows for the identification of bioactive molecules modulating stomatal aperture. Our proof-of-concept experiments demonstrate that a chemical can be carried from the cut root to the cotyledon of the sunflower seedling within 10 minutes. In addition, when plants are treated with ABA as a positive control, an increase in leaf surface temperature can be detected within minutes. Our method thus allows the efficient and rapid identification of novel molecules regulating stomatal aperture.

Identification of Novel Regulators of Plant Transpiration by Large-Scale Thermal Imaging Screening in Helianthus Annuus

We provide a method for identifying modulators of foliar transpiration by large-scale screening of a compound library.

Plant adaptation to biotic and abiotic stresses is governed by a variety of factors, among which the regulation of stomatal aperture in response to water ...

A Semiautomated ChIP-Seq Procedure for Large-scale Epigenetic Studies

Chromatin immunoprecipitation followed by sequencing (ChIP-Seq) is a powerful and widely used approach to profile chromatin DNA associated with specific histone modifications, such as H3K27ac, to help identify cis-regulatory DNA elements. The manual process to complete a ChIP-Seq is labor intensive, technically challenging, and often requires large-cell numbers (&#62;100,000 cells). The method described here helps to overcome those challenges. A complete semiautomated, microscaled H3K27ac ChIP-Seq procedure including cell fixation, chromatin shearing, immunoprecipitation, and sequencing library preparation, for batch of 48 samples for cell number inputs less than 100,000 cells is described in detail. The semiautonomous platform reduces technical variability, improves signal-to-noise ratios, and drastically reduces labor. The system can thereby reduce costs by allowing for reduced reaction volumes, limiting the number of expensive reagents such as enzymes, magnetic beads, antibodies, and hands-on time required. These improvements to the ChIP-Seq method suit perfectly for large-scale epigenetic studies of clinical samples with limited cell numbers in a highly reproducible manner.

This paper describes a semiautomated, microscaled ChIP-Seq protocol of DNA regions associated with a specific histone modification (H3K27ac) using a ChIP liquid-handler platform, followed by library preparation using tagmentation. The procedure includes control assessment for quality and quantity purposes and can be adopted to other histone modifications or transcription factors.

Chromatin immunoprecipitation followed by sequencing (ChIP-Seq) is a powerful and widely used approach to profile chromatin DNA associated with specific ...