Name: development of a colloidal gold-based immunochromatographic test strip for detection of cetacean myoglobin
Uploaded: 2016-07-13T13:00:00
Description: Watch this Scientific Journal Video about Development of a Colloidal Gold-based Immunochromatographic Test Strip for Detection of Cetacean Myoglobin at JoVE.com

We appreciate the colleagues in Taiwan Cetacean Society, Marine Biology and Cetacean Research Center of National Cheng Kung Univerisy, Farglory Ocean Park, and Animal Disease Diagnostic Center of National Chiayi Universiy for sample collection. This project was funded by grant to WCY from the Council of Agriculture of Taiwan (100AS-02.1-FB99).

Ethics Statement: The study was performed in accordance with international guidelines and approved by the Institutional Animal Care and Use Committee (IACUC) of National Chiayi University, approval ID: 99022. The cetacean sample use was permitted by Council of Agriculture of Taiwan (Research Permit 100M-02.1-C-99).
1. Muscle Sample Preparation and SDS-PAGE
Note: Muscle samples from 23 species including 16 species of marine mammals, 5 species of terres...

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Using a synthetic peptide conjugated to carrier protein is remarkably more effective compared to its cognate protein. For a sandwich-based technique, because the mAb is developed using epitopes with known relative locations, the two mAbs in this study are not likely to interfere with each other&#39;s interaction with the target antigen epitope. Moreover, the reactivity between the native protein and the antibody of mice immunized with the synthetic peptide-conjugate may be stronger than the reactivity between the native ...

Historically, cetacean meat has been consumed in many parts of the world and this consumption continues today1. Due to the trophic level of cetaceans, high levels of mercury and other toxins are known to be present in their meat2. Therefore, the consumption of cetacean meat could lead to a health problem not only for high-risk groups such as pregnant women but also for the general population3. Furthermore, the contamination of cetacean meat with zoonotic or potentially zoonotic pathogens can also occur during its processing and storage4. It is difficult even for experienced agents to identify cetacean meats by their appearance alone. Therefore, a reliable scientific method of identification is required to differentiate cetacean meat from other meats. This would help to limit the consumption of cetacean meat.
Current methods of species identification include molecular techniques and immunological methods. Molecular techniques, such as polymerase chain reaction (PCR) and DNA sequencing, can be used to identify samples not only from raw meat5 and decomposed samples6 but also from processed foods such as cooked sausage and feedstuffs7,8. Immunological methods, such as enzyme-linked immunosorbent assay (ELISA), are commonly applied in food production to detect the meat content of, for example, pork9, beef10 and catfish11. PCR-based DNA analysis for the identification of cetacean meat is available12, and has helped prevent the illegal international trade of cetacean meat in Japan, South Korea, the Philippines, Taiwan, Hong Kong, Russia, Norway, and the United States1. These methods are effective and reliable, but they can take hours or days to complete and involve laborious steps. The identification of cetacean meats is usually based on molecular techniques and there is currently no immunological method available. For regulatory agencies, it is highly desirable to develop a dependable and rapid technique that can be used in the field to identify cetacean meats. 
Immunochromatographic strips are used as detection tools with the advantage of producing rapid result via a simple protocol that is suitable for use in the field. The principles of the immunochromatographic strip and ELISA are very similar, and includes antibodies, antigens and labels. Many different labels such as colloidal gold, carbon and latex have been used in the development of immunochromatographic strips. At present, this method is commonly used for detecting antibiotics, toxin, bacteria and viruses13, but it is rarely used for identifying proteins in meat14,15. Here we propose a lateral-flow chromatographic enzyme immunoassay for rapid detection of cetacean myoglobin (Mb).

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	<tbody>
		<tr height="21">
			<td height="21" style="height:21px;width:512px;">Phosphate buffered saline</td>
			<td style="width:183px;">AMRESCO</td>
			<td style="width:148px;">J373</td>
			<td style="width:164px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:512px;">Protein G HP SpinTrap&#160;</td>
			<td>GE&#160;Healthcare</td>
			<td>28-9031-34</td>
			<td>spin column containing Protein G Sepharose</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:512px;">IsoStrip Mouse Monoclonal Antibody Isotyping Kit</td>
			<td>Roche</td>
			<td>11493027001</td>
			<td>Isotyping Strips, precoated with subclass- and light-chain-specific anti-mouse-Ig antibodies</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Mini Trans-Blot</td>
			<td>Bio-Rad</td>
			<td>170-3935</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Nitrocellulose membrane</td>
			<td>Whatman</td>
			<td>Z613630</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Antibody blocker solution&#160;</td>
			<td>LTK BioLaboratories</td>
			<td style="width:148px;"></td>
			<td>To minimize nonspecific binding interactions of nonspecific IgG in the samples</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:512px;">BCIP/NBT phosphatase substrate&#160;</td>
			<td>KPL</td>
			<td>50-81-00</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Protein Detector HRP Microwell Kit, Anti-Mouse</td>
			<td style="width:183px;">KPL</td>
			<td>54-62-18</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Nunc Immunoplate MaxiSorp ELISA plate</td>
			<td>Thermo&#160;Fisher Scientific</td>
			<td>EW-01928-08</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Multiskan&#160;EX ELISA reader&#160;</td>
			<td>Thermo&#160;Electron&#160;Corporation</td>
			<td>51118170</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Colloid gold (40 nm) solution&#160;</td>
			<td>REGA biotechnology Inc.</td>
			<td style="width:148px;"></td>
			<td>40-50 nm is appropriate for immunostrip</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Bovine serum albumin</td>
			<td>Gibco</td>
			<td>15561-020</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Rapid test immno-strip printer</td>
			<td>REGA biotechnology Inc.</td>
			<td>AGISMART RP-1000&#160;</td>
			<td>Only suited for small scale production of immunostrips for research and development purposes</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:512px;">Strip components (NC membranes, sample pads (#33 glass, S&#38;S), conjugate pads (#16S, S&#38;S) and absorbent pads (CF6, Whatman))</td>
			<td>REGA biotechnology Inc.</td>
			<td style="width:148px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Freund&#8217;s adjuvant and incomplete Freund&#8217;s adjuvant&#160;</td>
			<td style="width:183px;">Sigma-Aldrich</td>
			<td style="width:148px;">F5881, F5506</td>
			<td>Used to produce water-in-oil emulsions of immunogens</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:512px;">Acrylamide, gel buffer, ammonium persulfate (APS), tetramethylethylenediamine (TEMED)&#160;</td>
			<td style="width:183px;">Protech</td>
			<td style="width:148px;"></td>
			<td>Gel preparation for SDS-PAGE</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Coomassie brilliant blue R-250</td>
			<td style="width:183px;">Bio-Rad</td>
			<td style="width:148px;">1610436</td>
			<td>Protein staining in SDS-PAGE gels</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Laemmli sample buffer and &#946;-mercaptoethanol</td>
			<td style="width:183px;">Bio-Rad</td>
			<td style="width:148px;">1610737, 1610710</td>
			<td>Dilute protein samples before loading on SDS-PAGE gels</td>
		</tr>
	</tbody>
</table>

development of a colloidal gold-based immunochromatographic test strip for detection of cetacean myoglobin

This protocol describes the development of a colloidal gold immunochromatographic test strip based on the sandwich format that can be used to differentiate the myoglobin (Mb) of cetaceans from that of seals and other animals. The strip provides rapid and on-the-spot screening for cetacean meat, thereby restraining its illegal trade and consumption. Two monoclonal antibodies (mAbs) with reactivity toward the Mb of cetaceans were developed. The amino acid sequences of Mb antigenic reactive regions from various animals were analyzed in order to design two synthetic peptides (a general peptide and a specific peptide) and thereafter raise the mAbs (subclass IgG1). The mAbs were selected from hybridomas screened by indirect ELISA, western blot and dot blot. CGF5H9 was specific to the Mbs of rabbits, dogs, pigs, cows, goats, and cetaceans while it showed weak to no affinity to the Mbs of chickens, tuna and seals. CSF1H13 can bind seals and cetaceans with strong affinity but showed no affinity to other animals. Cetacean samples from four families (Balaenopteridae, Delphinidae, Phocoenidae and Kogiidae) were used in this study, and the results indicated that these two mAbs have broad binding ability to Mbs from different cetaceans. These mAbs were applied on a sandwich-type colloidal gold immunochromatographic test strip. CGF5H9, which recognizes many species, was colloid gold-labeled and used as the detection antibody. CSF1H13, which was coated on the test zone, detected the presence of cetacean and seal Mbs. Muscle samples from tuna, chicken, seal, five species of terrestrial mammals and 15 species of cetaceans were tested in triplicate. All cetacean samples showed positive results and all the other samples showed negative results.

Monoclonal antibody characteristics 
We developed two IgG1 mAbs (CGF5H9 and CSF1H13) recognizing two synthetic peptides (MKASEDLKKHGNTVLC and AIIHVLHSRHPAEFGC), respectively, of cetacean Mb, and these were used to construct a sandwich-type colloidal gold immunochromatographic test strip for the rapid detection of cetacean Mb. Figure 2 shows that CGF5H9 detects cetaceans and other mammals as a single stained band at a predicted molecular weight of ap...

Watch this Scientific Journal Video about Development of a Colloidal Gold-based Immunochromatographic Test Strip for Detection of Cetacean Myoglobin at JoVE.com

Development of a Colloidal Gold-based Immunochromatographic Test Strip for Detection of Cetacean Myoglobin

This protocol describes the development of two IgG class monoclonal antibodies (mAbs) strongly reactive to myoglobin of cetaceans. These mAbs are applied on a colloidal gold immunochromatographic test strip based on the sandwich format to differentiate the Mb of cetaceans from seal and other animals.

This protocol describes the development of a colloidal gold immunochromatographic test strip based on the sandwich format that can be used to ...

The overall goal of this colloidal gold immunochromatographic test strip is to differentiate the myoglobin of cetaceans from that of seals and other animals. This method can provide rapid and on-the-spot screening for cetacean meat, thereby restraining its illegal trade and consumption. The main advantage of this technique is that a successful result can be observed directly in five to ten minutes after homogenizing 03 gram of muscle, with outstanding specificity and sensitivity.So this method can provide rapid detection of cetacean meat in the field. It can also be applied to other meat such as horse meat, or pork. To design synthetic peptides for raising monoclonal antibodies with reactivity toward the myoglobin of cetaceans, the amino acid sequences of myoglobin antigenic reactive regions from various animals are analyzed.Begin by retrieving from GenBank the amino acid sequences of myoglobin from tuna, chicken, ostrich, domestic mammals, seal, and 18 species of cetaceans. Next, align the sequences using the proper software. Launch the Alignment Explorer by selecting the Align Edit/Build Alignment on the launch bar.Select Create New Alignment, and click OK.A dialog will appear asking, are you building a DNA or Protein Sequence alignment? Click the button labeled Protein, select Data Open Retrieve sequences from File, and select sequence file. Select the Edit Select All menu command to select all sites for every sequence in the data set for creating a multiple sequence alignment.Select Alignment Align by ClustalW from the main menu. Select BLOSUM as the protein weight matrix and then click the OK button. The third step is to analyze the sequence alignment.Focus on five antigenic reactive sites and find the fragment conserved among cetaceans. An asterisk symbolizes consensus in the alignment and indicates a position that has a single, fully-conserved residue. Two conserved fragments in cetaceans were found.Candidate sequence fragments are then synthesized and used to raise monoclonal antibodies. Begin this procedure by determining the optimal pH for the colloidal gold solution defined as the minimum pH that keeps the monoclonal antibody and colloidal gold solution mixture red in color for two hours. Add 0.15 micrograms of purified detecting monoclonal antibody to 100 microliters of colloidal gold solution with pH values varying from five to nine.For the purposes of this demonstration, pH six and pH eight are tested. pH eight was considered the optimal pH by this optimization step. Next, determine the optimal concentration of the monoclonal antibody by adding various amounts of purified detecting monoclonal antibody to 100 microliters of colloidal gold solution at pH eight.The optimum concentration, which is six micrograms per milliliter in this study, will keep the color of the mixture red with no black precipitate. Based on the results from the optimization steps, add 60 micrograms of purified detecting monoclonal antibody drop-wise to 10mL of colloidal gold solution. Emulsify the mixture gently at room temperature for ten minutes.Add two milliliters of a 5%BSA solution in PBS to the mixture and emulsify gently at room temperature for 15 minutes to reduce background interference. Centrifuge the mixture at 10, 000 times g for 30 minutes at four degrees Celsius. After centrifugation, carefully remove the supernatant with unconjugated antibody and suspend the resulting pellet in 4mL of PBS-T containing 1%BSA and 0.1%Tween-20.Repeat the centrifugation and suspension once or twice. Suspend the final precipitates in 1mL of PBS-T and store at four degrees Celsius until use. A graphic of the immune strip design is shown here.The dimensions of the cardboard, pads, and nitrocellulose membrane are listed in the protocol text. To prolong storage life, the immune strips should be prepared and assembled in a low-humidity laboratory environmental condition. Use a micropipette to add the colloid gold-labeled monoclonal antibody solution to the conjugate pad to saturate it and then dry the pad at 37 degrees Celsius for one hour before assembling.Once the conjugate pad is dry, use double-sided tape to first paste the nitrocellulose membrane onto the cardboard. Using an immunostrip printer, distribute the specific antigen capturing monoclonal antibody and the rapid anti-mouse IGG on the test zone and the control zone, respectively, on the nitrocellulose membrane. Maintain a distance of greater than five millimeters between the two zones.Then paste the conjugate pad on one side of the nitrocellulose membrane, and the absorbent pad on the other side, overlapping the pads on each side by about two millimeters. Place the sample pad over the conjugate pad by two millimeters and paste it on the cardboard. Use a paper cutter to create six-millimeter-wide strips.Pack the strips in an aluminum foil bag with dessicant and store at four degrees Celsius until use. To prepare a sample for the cross-reactivity test, add 1mL of PBS containing 0.1%BSA to 0.03 grams of raw muscle. And use a bamboo stick or a grinding rod to homogenize the sample.Hold the immune strip by the end opposite to the test area and dip the sample pad part into the specimen for five to ten minutes. Observe the result directly. Test various muscle samples in triplicate.The T test line is designed to show a positive signal when both monoclonal antibodies detect cetacean myoglobin. Because the myoglobin from non-cetacean animals can only be detected by one of these two monoclonal antibodies, the test line shows a negative result when muscle samples from other animals are tested. The C control line should always show a positive result because rapid anti-mouse IGG binds the colloid gold-labeled detection antibody.A failed result in the Control line indicates that the quality of the materials on the strip is poor. Western blood analysis using hybridoma supernatants shows that the CGF5H9 monoclonal antibody detects cetaceans and other mammals as a single stained band at a predicted molecular weight of approximately 17kDa. The common Minke whale shows a comparatively fainter band than the bands of other cetaceans.Bands are absent for tuna, seal, and chicken. Whereas a band at about 50kDa is observed for pig. Identical results are obtained by dot blood analysis.Although Western blood analysis using the CSF1H13 monoclonal antibody shows multiple nonspecific bands for pig and tuna, CSF1H13 is highly specific because it reacts only with cetaceans. And seal has a band at a predicted molecular weight of approximately 17kDa. Identical results are obtained by dot blood analysis.Results from Indirect ELISA of muscle extracts of different species using purified CGF5H9 demonstrate positive signals for cow, goat, dog, rabbit and cetaceans, a weak positive signal for pig, and negative signals for tuna, chicken, and seal. CSF1H13 shows high affinity towards cetaceans and seals. Both monoclonal antibodies can react strongly with all four cetacean species which are from different families, indicating their broad reactivity to diverse cetacean species.The specificity of the immune colloidal gold strip is shown by these representative results. The use of non-cetacean muscle samples results in only a single band at the control line. However, when cetacean muscle samples are used, the signal bands are present at both the test line and control line.Once mastered, the preparation of labeled antibodies and this construction of strips can be done in four hours if it's performed properly. When attempting this procedure, it's important to remember to design the peptide carefully. Use several methods for screening suitable monoclonal antibodies.And use a high quality of colloidal gold to prepare labeled antibodies. Following these procedures, other methods like PCR-based DNA analysis can be performed in order to answer additional questions, like the cetacean species and from where it came. The CSF1H13 monoclonal antibody which is strong and exhibits an affinity towards only marine mammals can be employed in various formats of ELISA that offer many other opportunities for studying the biological, physiological and chemical aspects of myoglobin in marine mammals.After watching this video, you should have a good understanding of how to develop specific monoclonal antibodies and subsequently apply them over quick test strip.

development-colloidal-gold-based-immunochromatographic-test-strip-for

Research

JoVE Journal

Biology

A Neuronal and Astrocyte Co-Culture Assay for High Content Analysis of Neurotoxicity

High Content Analysis (HCA) assays combine cells and detection reagents with automated imaging and powerful image analysis algorithms, allowing measurement of multiple cellular phenotypes within a single assay. In this study, we utilized HCA to develop a novel assay for neurotoxicity. Neurotoxicity assessment represents an important part of drug safety evaluation, as well as being a significant focus of environmental protection efforts. Additionally, neurotoxicity is also a well-accepted in vitro marker of the development of neurodegenerative diseases such as Alzheimer's and Parkinson's diseases. Recently, the application of HCA to neuronal screening has been reported. By labeling neuronal cells with &beta;III-tubulin, HCA assays can provide high-throughput, non-subjective, quantitative measurements of parameters such as neuronal number, neurite count and neurite length, all of which can indicate neurotoxic effects. However, the role of astrocytes remains unexplored in these models. Astrocytes have an integral role in the maintenance of central nervous system (CNS) homeostasis, and are associated with both neuroprotection and neurodegradation when they are activated in response to toxic substances or disease states. GFAP is an intermediate filament protein expressed predominantly in the astrocytes of the CNS. Astrocytic activation (gliosis) leads to the upregulation of GFAP, commonly accompanied by astrocyte proliferation and hypertrophy. This process of reactive gliosis has been proposed as an early marker of damage to the nervous system. The traditional method for GFAP quantitation is by immunoassay. This approach is limited by an inability to provide information on cellular localization, morphology and cell number. We determined that HCA could be used to overcome these limitations and to simultaneously measure multiple features associated with gliosis - changes in GFAP expression, astrocyte hypertrophy, and astrocyte proliferation - within a single assay. In co-culture studies, astrocytes have been shown to protect neurons against several types of toxic insult and to critically influence neuronal survival. Recent studies have suggested that the use of astrocytes in an in vitro neurotoxicity test system may prove more relevant to human CNS structure and function than neuronal cells alone. Accordingly, we have developed an HCA assay for co-culture of neurons and astrocytes, comprised of protocols and validated, target-specific detection reagents for profiling &beta;III-tubulin and glial fibrillary acidic protein (GFAP). This assay enables simultaneous analysis of neurotoxicity, neurite outgrowth, gliosis, neuronal and astrocytic morphology and neuronal and astrocytic development in a wide variety of cellular models, representing a novel, non-subjective, high-throughput assay for neurotoxicity assessment. The assay holds great potential for enhanced detection of neurotoxicity and improved productivity in neuroscience research and drug discovery.

This article describes a novel protocol and reagent set designed for sensitive measurement of neurotoxic effects of compounds and treatments on co-cultures of neurons and astrocytes using high content analysis. Results demonstrate that high content analysis represents an exciting novel technology for neurotoxicity assessment.

High Content Analysis (HCA) assays combine cells and detection reagents with automated imaging and powerful image analysis algorithms, allowing ...

Detection of Protein Ubiquitination

Ubiquitination, the covalent attachment of the polypeptide ubiquitin to target proteins, is a key posttranslational modification carried out by a set of three enzymes. They include ubiquitin-activating enzyme E1, ubiquitin-conjugating enzyme E2, and ubiquitin ligase E3. Unlike to E1 and E2, E3 ubiquitin ligases display substrate specificity. On the other hand, numerous deubiquitylating enzymes have roles in processing polyubiquitinated proteins. Ubiquitination can result in change of protein stability, cellular localization, and biological activity. Mutations of genes involved in the ubiquitination/deubiquitination pathway or altered ubiquitin system function are associated with many different human diseases such as various types of cancer, neurodegeneration, and metabolic disorders. The detection of altered or normal ubiquitination of target proteins may provide a better understanding on the pathogenesis of these diseases. &nbsp;Here, we describe protocols to detect protein ubiquitination in cultured cells in vivo and test tubes in vitro. These protocols are also useful to detect other ubiquitin-like small molecule modification such as sumolyation and neddylation.

Ubiquitination is a key posttranslational modification carried out by a set of three enzymes. Mutations of genes involved in this modification are associated with many different human diseases. Here, we describe protocols to detect protein ubiquitination in cultured cells in vivo and test tubes in vitro.

Ubiquitination, the covalent attachment of the polypeptide ubiquitin to target proteins, is a key posttranslational modification carried out by a set of ...

Preparation of Rat Brain Aggregate Cultures for Neuron and Glia Development Studies

An in vitro system that recapitulates the development and differentiation of progenitors into mature neurons and glia in the central nervous system (CNS) would provide a powerful platform for neuroscientists to investigate axo-glial interactions, properties and differentiation of multipotent progenitors, and progression of oligodendroglial lineage cells at the cellular and molecular level.  We describe here a CNS aggregate culture system from embryonic rat forebrains, which can be maintained in a serum-free medium up to 3-4 weeks and is used in our laboratory as a model to study neuron-glia interaction and CNS myelination.  This video clip will demonstrate how to isolate and grow these CNS aggregate cultures from E16 rat brain.  Furthermore, from the same brain dissection, highly enriched regular dissociated neuronal cultures can be readily obtained and used for various studies on CNS neurons or used for co-cultures with other cells. 

A protocols for an embryonic rat brain aggregate culture system is described. Multipotent progenitors in the aggregates can develop and differentiate into neurons, astrocytes and oligodendrocytes.

An in vitro system that recapitulates the development and differentiation of progenitors into mature neurons and glia in the central nervous system (CNS) ...

Analysis of the Development of a Morphological Phenotype as a Function of Protein Concentration in Budding Yeast

Gene deletion and protein overexpression are common methods for studying functions of proteins. In this article, we describe a protocol for analysis of phenotype development as a function of protein concentration at population and single-cell levels in Saccharomyces cerevisiae. Although this protocol is based on the overexpression of a protein, it can easily be adapted for morphological phenotypes dependent on suppression of protein expression. Our lab is interested in studying the signaling properties of the endocytic adaptor protein epsin. To that purpose we used a dominant negative approach in which we over-expressed the conserved Epsin N-Terminal Homology (ENTH) domain in order to interfere with the functions of endogenous epsin-2 (Ent2 or YLR206W). We observed that overexpression of the ENTH domain of Ent2 (ENTH2) in wild type cells led to a cell division defect that is dependent on the mislocalization of a family of scaffolding proteins, septins.

Gene deletion and protein overexpression are common methods for studying functions of proteins. In this article, we describe a protocol for analysis of phenotype development as a function of protein concentration at population and single-cell levels in Saccharomyces cerevisiae.

Gene deletion and protein overexpression are common methods for studying functions of proteins. In this article, we describe a protocol for analysis of ...

Development of automated imaging and analysis for zebrafish chemical screens.

We demonstrate the application of image-based high-content screening (HCS) methodology to identify small molecules that can modulate the FGF/RAS/MAPK pathway in zebrafish embryos. The zebrafish embryo is an ideal system for in vivo high-content chemical screens. The 1-day old embryo is approximately 1mm in diameter and can be easily arrayed into 96-well plates, a standard format for high throughput screening. During the first day of development, embryos are transparent with most of the major organs present, thus enabling visualization of tissue formation during embryogenesis. The complete automation of zebrafish chemical screens is still a challenge, however, particularly in the development of automated image acquisition and analysis. We previously generated a transgenic reporter line that expresses green fluorescent protein (GFP) under the control of FGF activity and demonstrated their utility in chemical screens 1. To establish methodology for high throughput whole organism screens, we developed a system for automated imaging and analysis of zebrafish embryos at 24-48 hours post fertilization (hpf) in 96-well plates 2. In this video we highlight the procedures for arraying transgenic embryos into multiwell plates at 24hpf and the addition of a small molecule (BCI) that hyperactivates FGF signaling 3. The plates are incubated for 6 hours followed by the addition of tricaine to anesthetize larvae prior to automated imaging on a Molecular Devices ImageXpress Ultra laser scanning confocal HCS reader. Images are processed by Definiens Developer software using a Cognition Network Technology algorithm that we developed to detect and quantify expression of GFP in the heads of transgenic embryos. In this example we highlight the ability of the algorithm to measure dose-dependent effects of BCI on GFP reporter gene expression in treated embryos.

We report the development of a system for automated imaging and analysis of zebrafish transgenic embryos in multiwell plates. This demonstrates the ability to measure dose dependent effects of a small molecule, BCI, on Fibroblast Growth Factor reporter gene expression and provide technology for establishing high-throughput zebrafish chemical screens.

We demonstrate the application of image-based high-content screening (HCS) methodology to identify small molecules that can modulate the FGF/RAS/MAPK ...

Western Blotting: Sample Preparation to Detection

Western blotting is an analytical technique used to detect specific proteins in a given sample of tissue homogenate or extract. It uses gel electrophoresis to separate native or denatured proteins by the length of the polypeptide (denaturing conditions) or by the 3-D structure of the protein (native/ non-denaturing conditions). The proteins are then transferred to a membrane (typically nitrocellulose or PVDF), where they are probed (detected) using antibodies specific to the target protein.

Western blotting is an analytical technique used to detect specific proteins in a given sample of tissue homogenate or extract.

Western blotting is an analytical technique used to detect specific proteins in a given sample of tissue homogenate or extract. It uses gel ...

A System for ex vivo Culturing of Embryonic Pancreas

The pancreas controls vital functions of our body, including the production of digestive enzymes and regulation of blood sugar levels1. Although in the past decade many studies have contributed to a solid foundation for understanding pancreatic organogenesis, important gaps persist in our knowledge of early pancreas formation2. A complete understanding of these early events will provide insight into the development of this organ, but also into incurable diseases that target the pancreas, such as diabetes or pancreatic cancer. Finally, this information will generate a blueprint for developing cell-replacement therapies in the context of diabetes.
 During embryogenesis, the pancreas originates from distinct embryonic outgrowths of the dorsal and ventral foregut endoderm at embryonic day (E) 9.5 in the mouse embryo3,4. Both outgrowths evaginate into the surrounding mesenchyme as solid epithelial buds, which undergo proliferation, branching and differentiation to generate a fully mature organ2,5,6. Recent evidences have suggested that growth and differentiation of pancreatic cell lineages, including the insulin-producing &beta;-cells, depends on proper tissue-architecture, epithelial remodeling and cell positioning within the branching pancreatic epithelium7,8. However, how branching morphogenesis occurs and is coordinated with proliferation and differentiation in the pancreas is largely unknown. This is in part due to the fact that current knowledge about these developmental processes has relied almost exclusively on analysis of fixed specimens, while morphogenetic events are highly dynamic.
 Here, we report a method for dissecting and culturing mouse embryonic pancreatic buds ex vivo on glass bottom dishes, which allow direct visualization of the developing pancreas (Figure 1). This culture system is ideally devised for confocal laser scanning microscopy and, in particular, live-cell imaging. Pancreatic explants can be prepared not only from wild-type mouse embryos, but also from genetically engineered mouse strains (e.g. transgenic or knockout), allowing real-time studies of mutant phenotypes. Moreover, this ex vivo culture system is valuable to study the effects of chemical compounds on pancreatic development, enabling to obtain quantitative data about proliferation and growth, elongation, branching, tubulogenesis and differentiation. In conclusion, the development of an ex vivo pancreatic explant culture method combined with high-resolution imaging provides a strong platform for observing morphogenetic and differentiation events as they occur within the developing mouse embryo.

A System for ex vivo Culturing of Embryonic Pancreas

Here, we describe a method for isolation, culture and manipulation of mouse embryonic pancreas. This represents an excellent ex vivo system for studying various aspects of pancreatic development, including morphogenesis, differentiation and growth. Pancreatic bud explants can be cultured for several days and used in a range of different applications, including whole-mount immunofluorescence and live imaging.

The pancreas controls vital functions of our body,  including the production of digestive enzymes and regulation of blood sugar  levels1. Although in the ...

Tangential Flow Ultrafiltration: A  &ldquo;Green&rdquo; Method for the Size Selection and Concentration of Colloidal Silver Nanoparticles

Nowadays, AgNPs are extensively used in the manufacture of consumer products,1 water disinfectants,2 therapeutics,1, 3 and biomedical devices4 due to their powerful antimicrobial properties.3-6 These nanoparticle applications are strongly influenced by the AgNP size and aggregation state. Many challenges exist in the controlled fabrication7 and size-based isolation4,8 of unfunctionalized, homogenous AgNPs that are free from chemically aggressive capping/stabilizing agents or organic solvents.7-13 Limitations emerge from the toxicity of reagents, high costs or reduced efficiency of the AgNP synthesis or isolation methods (e.g., centrifugation, size-dependent solubility, size-exclusion chromatography, etc.).10,14-18 To overcome this, we recently showed that TFU permits greater control over the size, concentration and aggregation state of Creighton AgNPs (300 ml of 15.3 &mu;g ml-1 down to 10 ml of 198.7 &mu;g ml-1) than conventional methods of isolation such as ultracentrifugation.19
TFU is a recirculation method commonly used for the weight-based isolation of proteins, viruses and cells.20,21 Briefly, the liquid sample is passed through a series of hollow fiber membranes with pore size ranging from 1,000 kD to 10 kD. Smaller suspended or dissolved constituents in the sample will pass through the porous barrier together with the solvent (filtrate), while the larger constituents are retained (retentate). TFU may be considered a "green" method as it neither damages the sample nor requires additional solvent to eliminate toxic excess reagents and byproducts. Furthermore, TFU may be applied to a large variety of nanoparticles as both hydrophobic and hydrophilic filters are available.
The two main objectives of this study were: 1) to illustrate the experimental aspects of the TFU approach through an invited video experience and 2) to demonstrate the feasibility of the TFU method for larger volumes of colloidal nanoparticles and smaller volumes of retentate. First, unfuctionalized AgNPs (4 L, 15.2 &mu;g ml-1) were synthesized using the well-established Creighton method22,23 by the reduction of AgNO3 with NaBH4. AgNP polydispersity was then minimized via a 3-step TFU using a 50-nm filter (460 cm2) to remove AgNPs and AgNP-aggregates larger than 50 nm, followed by two 100-kD (200 cm2 and 20 cm2) filters to concentrate the AgNPs. Representative samples were characterized using transmission electron microscopy, UV-Vis absorption spectrophotometry, Raman spectroscopy, and inductively coupled plasma optical emission spectroscopy. The final retentate consisted of highly concentrated (4 ml, 8,539.9 &mu;g ml-1) yet lowly aggregated and homogeneous AgNPs of 1-20 nm in diameter. This corresponds to a silver concentration yield of about 62%.

Tangential flow ultrafiltration (TFU) is a recirculation method used for the weight-based separation of biosamples. TFU was adapted to size-select (1-20 nm diameter) and highly concentrate a large volume of polydisperse silver nanoparticles (4 L of 15.2 &mu;g ml-1 down to 4 ml of 8,539.9 &mu;g ml-1) with minimal aggregation.

Nowadays, AgNPs are extensively used in the manufacture of consumer products,1 water disinfectants,2 therapeutics,1, 3 and biomedical devices4 due to ...

Cell Tracking Using Photoconvertible Proteins During Zebrafish Development

Embryogenesis is a dynamic process that is best studied by using techniques that allow the documentation of developmental changes in vivo. The use of genetically-encoded fluorescent proteins has proven a valuable strategy for elucidating dynamic morphogenetic processes as they occur in the intact organism. During the past decade, the development of photoactivatable and photoconvertible fluorescent proteins has opened the possibility to investigate the fate of discrete subpopulations of tagged proteins1. Unlike photoactivatable proteins, photoconvertible fluorescent proteins (PCFPs) are readily tracked and imaged in their native emission state prior to photoconversion, making it easier to identify and select regions by optical inspection. PCFPs, such as Kaede2, KikGR3, Dendra4 and EosFP5, can be shifted from green to red upon exposure to UV or blue light due to a His-Tyr-Gly tripeptide sequence which forms a green chromophore that can be photoconverted to a red one by a light-catalyzed &beta;-elimination and subsequent extension of a &pi;-conjugated system3. PCFPs and their monomeric variants are useful tools for tracking cells6-10 and studying protein dynamics11-14, respectively. During recent years, PCFPs have been expressed in different animal model, such as zebrafish6, chicken7,8 and mouse9,10 for cell fate tracking. Here we report a protocol for cell-specific photoconversion of PCFPs in the living zebrafish embryo and further tracking of photoconverted proteins at later developmental stages. This methodology allows studying, in a tissue-specific manner, cell biological events underlying morphogenesis in the zebrafish animal model.

Here, we present a method for the photoactivated switch of photoconvertible fluorescent proteins (PCFPs) in the living zebrafish embryo and further tracking of photoconverted protein at specific time points during development. This methodology allows monitoring of cell biological events underlying different developmental processes in a live vertebrate organism.

Embryogenesis is a dynamic process that is best studied by using techniques that allow the documentation of developmental changes in vivo. The use of ...

Blastomere Explants to Test for Cell Fate Commitment During Embryonic Development

Fate maps, constructed from lineage tracing all of the cells of an embryo, reveal which tissues descend from each cell of the embryo. Although fate maps are very useful for identifying the precursors of an organ and for elucidating the developmental path by which the descendant cells populate that organ in the normal embryo, they do not illustrate the full developmental potential of a precursor cell or identify the mechanisms by which its fate is determined. To test for cell fate commitment, one compares a cell's normal repertoire of descendants in the intact embryo (the fate map) with those expressed after an experimental manipulation. Is the cell's fate fixed (committed) regardless of the surrounding cellular environment, or is it influenced by external factors provided by its neighbors? Using the comprehensive fate maps of the Xenopus embryo, we describe how to identify, isolate and culture single cleavage stage precursors, called blastomeres. This approach allows one to assess whether these early cells are committed to the fate they acquire in their normal environment in the intact embryo, require interactions with their neighboring cells, or can be influenced to express alternate fates if exposed to other types of signals.

The fate of an individual embryonic cell can be influenced by inherited molecules and/or by signals from neighboring cells. Utilizing fate maps of the cleavage stage Xenopus embryo, single blastomeres can be identified for culture in isolation to assess the contributions of inherited molecules versus cell-cell interactions.

Fate maps, constructed from lineage tracing all of the cells of an embryo, reveal  which tissues descend from each cell of the embryo.  Although fate maps ...