We thank Dr. Antonio Quesada from the Universidad Aut&#243;noma de Madrid for providing cyanobacterial strains. This work was funded by the Subdirecci&#243;n General de Proyectos de Investigaci&#243;n of the Spanish Ministerio de Econom&#237;a y Competitividad (MINECO), grants no. AYA2011-24803 and ESP2014-58494-R.

1. Preparation of the Immunogens
<ol>
	<li>Grow each cyanobacterial strain in the corresponding culture medium under conditions described in Table 1. 
	NOTE: Growth medium and culture conditions for each cyanobacteria strain are listed in Table 1. All the cyanobacterial strains, with the exception of K17, belong to Antonio Quesada&#39;s group from Autonoma University (Madrid, Spain). The antibody against Planktothrix rubescens was generated from a natural sample ...

<ol>
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D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Evaluation+of+methods+for+the+isolation,+detection+and+quantification+of+cyanobacterial+hepatotoxins.">Evaluation of methods for the isolation, detection and quantification of cyanobacterial hepatotoxins.</a> Aquat. Toxicol. 78 (4), 382-397 (2006).</li><li>Weller, M. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Immunoassays+and+biosensors+for+the+detection+of+cyanobacterial+toxins+in+water.">Immunoassays and biosensors for the detection of cyanobacterial toxins in water.</a> Sensors. 13 (11), 15085-15112 (2013).</li><li>Baker, J. A., Neilan, B. A., Entsch, B., McKay, D. B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Identification+of+cyanobacteria+and+their+toxigenicity+in+environmental+samples+by+rapid+molecular+analysis.">Identification of cyanobacteria and their toxigenicity in environmental samples by rapid molecular analysis.</a> Environ. Toxicol. 16 (6), 472-482 (2001).</li><li>Li, H., Singh, A. K., McIntyre, L. M., Sherman, L. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Differential+gene+expression+in+response+to+hydrogen+peroxide+and+the+putative+PerR+regulon+of+Synechocystis+sp.+Strain+PCC+6803.">Differential gene expression in response to hydrogen peroxide and the putative PerR regulon of Synechocystis sp. Strain PCC 6803.</a> J. Bacteriol. 186 (11), 3331-3345 (2004).</li><li>Anderson, D. M., Cembella, A. D., Hallegraeff, G. 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A., Garc&#237;a-Villadangos, M., Moreno-Paz, M., Patricia Cruz-Gil, P., G&#243;mez-Elvira, J., Parro, V. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+200-Antibody+microarray+biochip+for+environmental+monitoring:+Searching+for+universal+microbial+biomarkers+through+immunoprofiling.">A 200-Antibody microarray biochip for environmental monitoring: Searching for universal microbial biomarkers through immunoprofiling.</a> Anal. Chem. 80 (21), 7970-7979 (2008).</li><li>Delehanty, J. B., Ligler, F. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+microarray+immunoassay+for+simultaneous+detection+of+proteins+and+bacteria.">A microarray immunoassay for simultaneous detection of proteins and bacteria.</a> Anal. Chem. 74 (21), 5681-5687 (2002).</li><li>Ligler, F. S., Taitt, C. R., Shriver-Lake, L. 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The authors have nothing to disclose.

Here, a multiplex fluorescent sandwich immunoassay using the CYANOCHIP, a 17-antibody microarray for the detection and identification of a wide range of cyanobacterial genera, is described22. These cyanobacteria represent the most frequent benthic and planktonic genera in freshwater habitats, some of them being toxin producers. Recently, the fluorescent sandwich immunoassay format has been used to identify microorganisms and/or bioanalytes in environmental applications26...

The detection and monitoring of microorganisms in complex natural microbial communities are crucial in many fields, including biomedicine, environmental ecology, and astrobiology. Cyanobacteria are prokaryotic microorganisms well-known for their ability to form blooms (excessive proliferation) of cells in fresh water. They are ubiquitous, and many species are able to produce toxins, leading not only to a potential risk for human health, but also to an ecological impact. In this regard, it is essential to develop rapid and sensitive methods for the early detection of cyanobacteria and/or their toxins in soil and water. For this purpose, a multiplex fluorescent sandwich microarray immunoassay (FSMI) has been developed as a tool for water managers to help them in making decisions and, consequently, in implementing proper water management programs.
A diverse range of methods has been developed to detect and identify cyanobacterial cells and cyanotoxins in soil and water, including optical microscopy, molecular biology, and immunological techniques. These methods can vary greatly in the information they provide. Microscopic techniques are based on cell morphology and the detection of in vivo fluorescence from cyanobacterial pigments, such as phycocyanin or chlorophyll a1. Although they are quick and cheap methods for real-time and frequent monitoring that inform about the type and number of cyanobacteria present in a sample, they do not give information about the potential toxicity. In addition, they require a certain level of expertise, considering that it is often very difficult to distinguish between closely related species2. To overcome these limitations, light microscopy must be accompanied by both biological and biochemical screening assays and physicochemical methods for the identification and quantification of cyanotoxins.
Enzyme-linked immunosorbent assays (ELISA), protein phosphate inhibition assays (PPIA), and neurochemical tests in mice are examples of biochemical screening assays for the detection of cyanotoxins. While the first two are rapid and sensitive methodologies, false positives have been described when using ELISA and PPIA tests are restricted to three types of toxins. The mouse bioassay is a qualitative technique with low sensitivity and precision, and special licensing and training is required. In addition, it does not give information about the type of toxins present in a sample. Cyanotoxins can be identified and quantified by other analytical methods, such as high-performance liquid chromatography (HPLC), liquid chromatography-mass spectrometry (LC-MS), gas chromatography (GC), gas chromatography-mass spectrometry (GC-MS), or matrix-assisted laser desorption/ionization time of flight (MALDI-TOF). However, this is only possible if reference standards, which are needed to determine individual toxin concentrations in complex samples, are available3,4. Moreover, these methods are time-consuming; require costly equipment, supplies, and sample preparation; and must be performed by experienced and specialized staff.
Molecular-based methods have been applied for decades to detect, identify, and quantify cyanobacteria and their corresponding cyanotoxins thanks to the sequence information published in the genome databases (e.g., National Center for Biotechnology Information, NCBI). Among these methods are those based on the polymerase chain reaction (PCR), which requires the design of sets of primers for DNA amplification and depend on previous knowledge of DNA sequences of different cyanobacterial species. While gene detection, like the phycocyanin operon, leads to accurate identification at the genus level, some species or strains are undetected with this method. However, toxin-encoding genes, such as those belonging to the microcystin operon, facilitate the identification of toxins in samples where the producers are scarce5. Nonetheless, the detection of toxin markers by PCR does not necessarily imply toxicity in the environment. Furthermore, the set of primers developed to analyze the whole range of species of cyanobacteria and toxin producers present in a sample is still incomplete, and further studies must be done to identify unknown species. Other molecular techniques are non-PCR-based, such as fluorescence in situ hybridization (FISH) and DNA microarrays.
In the last two decades, microarray technology has gained importance in many fields of application, particularly in environmental monitoring. DNA microarrays allow for discrimination between species and analytes4,6,7,8,9,10, but they are considered very laborious and time-consuming tasks that involve multiple steps (e.g., microarray performance, DNA extraction, PCR amplification, and hybridization). For that reason, less time-consuming assays based on antibodies, such as sandwich and competitive immunological microarrays, have become an essential and reliable high-throughput method for the detection of multiple environmental analytes11,12,13. The capability of antibodies to specifically recognize their target compounds and to detect small amounts of analytes and proteins, along with the possibility of producing antibodies against almost any substance, make antibody microarrays a powerful technique for environmental purposes. In addition, the capability of achieving multiple analyses in a single assay, with limits of detection ranging from ppb to ppm, is one of the main advantages of this method14.
Antibody-based biosensors have proved to be sensitive and rapid tools for the detection of a wide range of pathogens and toxins in environmental monitoring15,16,17,18,19,20,21. While DNA methods involve several steps, the antibody-based microarrays only require a small sample preparation that is mainly based on a short lysis step in an appropriate solution buffer. Delehanty and Ligler15 reported the simultaneous detection of proteins and bacterial analytes in complex mixtures based on an antibody sandwich immunoassay capable of detecting a protein concentration of 4 ppb and 104 cfu/mL of cells. Szkola et al.21 have developed a cheap and reliable multiplex microarray for the simultaneous detection of proteotoxins and small toxins, compounds that might be used in biological warfare. They detected concentrations of ricin toxin, with a limit of detection of 3 ppb, in less than 20 min. Recently, the CYANOCHIP, an antibody microarray-based biosensor for the in situ detection of toxic and nontoxic cyanobacteria, has been described22. This microarray allows for the identification of potential cyanobacterial blooms, mostly in aquatic environments, which are difficult to identify microscopically. The limit of detection of the microarray is 102 - 103 cells for most species, turning this biosensor into a cost-effective tool for the multiplex detection and identification of cyanobacteria, even at the species level. All these properties make the antibody microarray technique, and particularly the method presented in this work, a quicker and simpler method compared to the aforementioned techniques.
This work presents two examples of experiments that use an antibody microarray-based biosensor to detect the presence of cyanobacteria in soil and water samples. It is a simple and reliable method based on a sandwich immunoassay format that requires very small sample volumes and very basic sample preparation. The method requires a short time and can be easily performed in the field.

<table border="0" cellpadding="0" cellspacing="0" width="1143">
	<tbody>
		<tr height="25">
			<td height="25" style="height:25px;width:351px;">0.22 mm pore diameter filters</td>
			<td style="width:248px;">Millipore</td>
			<td style="width:119px;">GSWP04700</td>
			<td style="width:427px;">For preparation of immunogens</td>
		</tr>
		<tr height="25">
			<td height="25" style="height:25px;width:351px;">Eppendorf&#160; 5424R microcentrifuge</td>
			<td style="width:248px;">Fisher Scientific</td>
			<td style="width:119px;"></td>
			<td>For preparation of immunogens</td>
		</tr>
		<tr height="25">
			<td height="25" style="height:25px;width:351px;">Phosphate buffer saline (PBS) pH 7.4 (10X)</td>
			<td style="width:248px;">Thermofisher Scientific</td>
			<td style="width:119px;">70011036</td>
			<td>50 mM potassium phosphate, 150 mM NaCl, pH 7.4</td>
		</tr>
		<tr height="25">
			<td height="25" style="height:25px;width:351px;">Ultrasonic processor UP50H</td>
			<td style="width:248px;">Hielscher</td>
			<td style="width:119px;"></td>
			<td>For preparation of immunogens</td>
		</tr>
		<tr height="25">
			<td height="25" style="height:25px;width:351px;">Complete Freund&#39;s adjuvant&#160;</td>
			<td style="width:248px;">Sigma-Aldrich</td>
			<td style="width:119px;">F5881</td>
			<td>Immunopotentiator</td>
		</tr>
		<tr height="25">
			<td height="25" style="height:25px;width:351px;">Incomplete Freud&#39;s adjuvant</td>
			<td style="width:248px;">Sigma-Aldrich&#160;</td>
			<td style="width:119px;">F5506</td>
			<td>For boost injections</td>
		</tr>
		<tr height="25">
			<td height="25" style="height:25px;width:351px;">Protein A antibody purification kit&#160;&#160;</td>
			<td style="width:248px;">Sigma-Aldrich</td>
			<td style="width:119px;">PURE1A&#160;</td>
			<td>For isolation of IgG</td>
		</tr>
		<tr height="25">
			<td height="25" style="height:25px;width:351px;">Centrifugal filter devices MWCO&#60;100 KDa</td>
			<td style="width:248px;">Millipore</td>
			<td style="width:119px;">UFC510096-96K</td>
			<td>For isolation of IgG</td>
		</tr>
		<tr height="25">
			<td height="25" style="height:25px;width:351px;">Dialysis tubings, benzoylated</td>
			<td style="width:248px;">Sigma-Aldrich</td>
			<td style="width:119px;">D7884-10FT</td>
			<td>For isolation of IgG</td>
		</tr>
		<tr height="25">
			<td height="25" style="height:25px;width:351px;">Illustra Microspin G-50 columns&#160;</td>
			<td style="width:248px;">GE-HealthCare</td>
			<td style="width:119px;">GE27-5330-02</td>
			<td>For isolation of IgG</td>
		</tr>
		<tr height="25">
			<td height="25" style="height:25px;width:351px;">Bradford reagent</td>
			<td style="width:248px;">Sigma-Aldrich</td>
			<td style="width:119px;">B6916-500 mL</td>
			<td>To quantify the antibody concentration</td>
		</tr>
		<tr height="25">
			<td height="25" style="height:25px;width:351px;">MicroBCA protein assay kit&#160;</td>
			<td style="width:248px;">Thermo Scientific</td>
			<td style="width:119px;">23235</td>
			<td>To quantify the antibody concentration</td>
		</tr>
		<tr height="25">
			<td height="25" style="height:25px;width:351px;">Protein arraying buffer 2X</td>
			<td style="width:248px;">Whatman (Sigma Aldrich)&#160;</td>
			<td style="width:119px;">S00537</td>
			<td>Printing buffer; 30-40% glycerol in 1X PBS with 0.01% Tween 20</td>
		</tr>
		<tr height="25">
			<td height="25" style="height:25px;width:351px;">Tween 20&#160;</td>
			<td style="width:248px;">Sigma-Aldrich&#160;</td>
			<td style="width:119px;">P9416</td>
			<td>Non-ionic detergent</td>
		</tr>
		<tr height="25">
			<td height="25" style="height:25px;">Bovine serum albumin (BSA)</td>
			<td style="width:248px;">Sigma-Aldrich&#160;</td>
			<td style="width:119px;">A9418</td>
			<td>Control&#160; for printing; blocking reagent</td>
		</tr>
		<tr height="25">
			<td height="25" style="height:25px;width:351px;">384-wells microplate</td>
			<td style="width:248px;">Genetix</td>
			<td style="width:119px;">X6004</td>
			<td>For antibody printing</td>
		</tr>
		<tr height="25">
			<td height="25" style="height:25px;width:351px;">Robot arrayer for multiple slides</td>
			<td style="width:248px;">MicroGrid II TAS arrayer from Digilab</td>
			<td style="width:119px;"></td>
			<td>For antibody printing</td>
		</tr>
		<tr height="25">
			<td height="25" style="height:25px;">Epoxy substrate glass slides</td>
			<td style="width:248px;">Arrayit corporation</td>
			<td style="width:119px;">VEPO25C</td>
			<td>Solid support for antibody printing</td>
		</tr>
		<tr height="25">
			<td height="25" style="height:25px;width:351px;">Alexa Fluor-647 Succinimidyl-ester&#160;</td>
			<td style="width:248px;">Molecular probes</td>
			<td style="width:119px;">A20006</td>
			<td>Fluorochrome</td>
		</tr>
		<tr height="25">
			<td height="25" style="height:25px;">DMSO&#160;</td>
			<td style="width:248px;">Sigma-Aldrich&#160;</td>
			<td style="width:119px;">D8418</td>
			<td>Fluorochrome dissolvent</td>
		</tr>
		<tr height="25">
			<td height="25" style="height:25px;">Heidolph Titramax vibrating platform shaker</td>
			<td style="width:248px;">Fisher Scientific</td>
			<td style="width:119px;"></td>
			<td>For antibody labeling&#160;</td>
		</tr>
		<tr height="24">
			<td height="24" style="height:24px;">Illustra Microspin G-50 columns&#160;</td>
			<td style="width:248px;">Healthcare</td>
			<td style="width:119px;">27-5330-01</td>
			<td>For purification of labeled antibodies</td>
		</tr>
		<tr height="25">
			<td height="25" style="height:25px;">Safe seal brown 0,5 ml tubes</td>
			<td style="width:248px;">Sarstedt</td>
			<td style="width:119px;">72,704,001</td>
			<td>For labeled antibodies storage&#160;</td>
		</tr>
		<tr height="25">
			<td height="25" style="height:25px;">Nanodrop 1000 spectrophotometer</td>
			<td style="width:248px;">Thermo Scientific</td>
			<td style="width:119px;"></td>
			<td>To quantify antibody concentration and labeling efficiency</td>
		</tr>
		<tr height="25">
			<td height="25" style="height:25px;width:351px;">3 &#181;m pore size polycarbonate 47 mm diameter filter</td>
			<td style="width:248px;">Millipore</td>
			<td style="width:119px;">TMTP04700</td>
			<td>To concentrate cells</td>
		</tr>
		<tr height="25">
			<td height="25" style="height:25px;width:351px;">1M Trizma hydrochloride solution pH 8</td>
			<td style="width:248px;">Sigma-Aldrich&#160;</td>
			<td style="width:119px;">T3038</td>
			<td>For TBSTRR preparation; to block slides</td>
		</tr>
		<tr height="25">
			<td height="25" style="height:25px;">Sodium chloride</td>
			<td style="width:248px;">Sigma-Aldrich&#160;</td>
			<td style="width:119px;">S7653</td>
			<td>For TBSTRR preparation</td>
		</tr>
		<tr height="25">
			<td height="25" style="height:25px;">20 &#181;m nylon filters&#160;</td>
			<td style="width:248px;">Millipore</td>
			<td style="width:119px;">NY2004700</td>
			<td>For environmental extract preparation</td>
		</tr>
		<tr height="25">
			<td height="25" style="height:25px;">10-12 mm filter holders</td>
			<td style="width:248px;">Millipore</td>
			<td style="width:119px;">SX0001300</td>
			<td>For environmental extract preparation</td>
		</tr>
		<tr height="25">
			<td height="25" style="height:25px;width:351px;">Protease inhibitor cocktail</td>
			<td style="width:248px;">Sigma-Aldrich&#160;</td>
			<td style="width:119px;">P8340</td>
			<td>For environmental extract storage</td>
		</tr>
		<tr height="25">
			<td height="25" style="height:25px;width:351px;">1M Trizma hydrochloride solution pH 9</td>
			<td style="width:248px;">Sigma-Aldrich&#160;</td>
			<td style="width:119px;">T2819</td>
			<td>To block slides</td>
		</tr>
		<tr height="25">
			<td height="25" style="height:25px;">Heidolph Duomax 1030 rocking platform shaker</td>
			<td style="width:248px;">VWR</td>
			<td style="width:119px;"></td>
			<td>To block slides; for incubation processes&#160;</td>
		</tr>
		<tr height="25">
			<td height="25" style="height:25px;width:351px;">VWR Galaxy miniarray microcentrifuge</td>
			<td style="width:248px;">VWR</td>
			<td style="width:119px;">C1403-VWR</td>
			<td>To dry slides</td>
		</tr>
		<tr height="25">
			<td height="25" style="height:25px;width:351px;">Multi-Well microarray hybridization cassette</td>
			<td style="width:248px;">Arrayit corporation</td>
			<td>AHC1X24</td>
			<td>Cassette for 24 assays per slide</td>
		</tr>
		<tr height="25">
			<td height="25" style="height:25px;width:351px;">GenePix 4100A microarray scanner&#160;</td>
			<td style="width:248px;">Molecular Devices</td>
			<td style="width:119px;"></td>
			<td>Scanner for fluorescence</td>
		</tr>
		<tr height="25">
			<td height="25" style="height:25px;width:351px;">GenePix Pro Software</td>
			<td style="width:248px;">Molecular Devices</td>
			<td style="width:119px;"></td>
			<td>Software for image analysis and quantification</td>
		</tr>
	</tbody>
</table>

experimental protocol for detecting cyanobacteria in liquid and solid samples with an antibody microarray chip

Global warming and eutrophication make some aquatic ecosystems behave as true bioreactors that trigger rapid and massive cyanobacterial growth; this has relevant health and economic consequences. Many cyanobacterial strains are toxin producers, and only a few cells are necessary to induce irreparable damage to the environment. Therefore, water-body authorities and administrations require rapid and efficient early-warning systems providing reliable data to support their preventive or curative decisions. This manuscript reports an experimental protocol for the in-field detection of toxin-producing cyanobacterial strains by using an antibody microarray chip with 17 antibodies (Abs) with taxonomic resolution (CYANOCHIP). Here, a multiplex fluorescent sandwich microarray immunoassay (FSMI) for the simultaneous monitoring of 17 cyanobacterial strains frequently found blooming in freshwater ecosystems, some of them toxin producers, is described. A microarray with multiple identical replicates (up to 24) of the CYANOCHIP was printed onto a single microscope slide to simultaneously test a similar number of samples. Liquid samples can be tested either by direct incubation with the antibodies (Abs) or after cell concentration by filtration through a 1- to 3-&#956;m filter. Solid samples, such as sediments and ground rocks, are first homogenized and dispersed by a hand-held ultrasonicator in an incubation buffer. They are then filtered (5 - 20 &#956;m) to remove the coarse material, and the filtrate is incubated with Abs. Immunoreactions are revealed by a final incubation with a mixture of the 17 fluorescence-labeled Abs and are read by a portable fluorescence detector. The whole process takes around 3 h, most of it corresponding to two 1-h periods of incubation. The output is an image, where bright spots correspond to the positive detection of cyanobacterial markers.

This work describes a multiplex immunoassay test for the simultaneous identification of the most relevant freshwater cyanobacterial species (Table 1) using the CYANOCHIP antibody microarray. The microarray can be a 3 x 8 microarray format printed onto microscope slides. Each microarray is made up of a set of 17 antibodies printed in a triplicate spot pattern, their corresponding pre-immune antibodies and BSA as negative controls. The microarrays also include a fluorescent...

Watch this Scientific Journal Video about Experimental Protocol for Detecting Cyanobacteria in Liquid and Solid Samples with an Antibody Microarray Chip at JoVE.com

Experimental Protocol for Detecting Cyanobacteria in Liquid and Solid Samples with an Antibody Microarray Chip

The presence of cyanobacterial toxins in fresh water reservoirs for human consumption is a major concern for water management authorities. To evaluate the risk of water contamination, this article describes an protocol for the in-field detection of cyanobacterial strains in liquid and solid samples by using an antibody microarray chip.

Experimental Protocol for Detecting Cyanobacteria in Liquid and Solid Samples with an Antibody Microarray Chip

Global warming and eutrophication make some aquatic ecosystems behave as true bioreactors that trigger rapid and massive cyanobacterial growth; this has ...

The overall goal of this procedure is to determine the presence of multiple cyanobacterial strains in liquid and solid samples using a fluorescence microarray immunoassay. This method can help answer key questions in the environmental, monitoring and water management fields, such as the presence of toxins produced protoxin-producing bacteria before the blooms become visible to the naked eyes. The main advantage of this technique is that multiple cyanobacterial strains and multiple samples can be monitored simultaneously in a three, four-hour period, both in situ or in the laboratory.So, these method can provide insight into biodiversity. It can also be applied to other fields, such as monitoring agricultural installations, life detection in strain environments or planetary exploration. Generally, individuals new to this method will not struggle.Because of the simplicity in the sample processing and the easier the interpretation of the results. After producing and purifying antibodies according to the text protocol, add 100 microliters of DMSO into a commercial vial containing dye for labeling, one milligram of protein. Once the dye is dissolved, label the purified antibodies by adding two microliters of the dye to 50 microliters of each antibody preparation.Maintain the labeling reactions at ambient temperature under continuous agitation on a vibrating platform for one hour. After purifying the labeled antibodies according to the text protocol, load a small aliquot into a spectrophotometer and measure the absorbance at 280 and 650 nanometers. Calculate the labeling efficiencies by following the supplier recommendations.To make a CYANOCHIP, prepare 30 microliters of each purified antibody by mixing one milligram per milliliter of antibody in a 1X protein printing buffer with 01%volume per volume of Tween 20. Prepare 30 microliters of the following printing solutions as controls. 1X protein printing buffer with 01%of volume per volume of Tween 20.Each protein A purified preimmune serum at one milligram per milliliter in 1X protein printing buffer with 01%Tween 20 and one millgram per milliliter of BSA and 1X protein printing buffer with 01%Tween 20. Add 30 microliters per well of the prepared printing solutions to the high-quality 384 well microplates. After setting up the printing robot and slide substrates according to the text protocol, spot all the antibodies and the controls onto the slides in a triplicate spot pattern approximately 180 to 200 micron spot diameter.For sampling in the environment, use a sterile syringe to collect one to 100 milliliters of liquids and concentrate the cells by passing the sample through a three micron pore size filter. If needed, collect solid samples from rocks or soils and keep them in sterile tubes. Samples can be assayed in a small field lab.Add one milliliter of extraction incubation buffer to recover the biomass collected in the filter and use a spatular to scrape the filter into a 15 milliliter tube. With a handheld ultrasonic processor, or by pipetting up and down several times, this aggregate and homogenize the sample. In addition, weigh up to 0.5 grams of the solid sample in a separate 10 milliliter tube and add up to two milliliters of extraction buffer.Immerse a sonicator probe into the tube and sonicate with a handheld ultrasonic processor or other ultrasonication device. While keeping the sample on ice, perform at least five 30 second cycles at 30 kilohertz, stopping for 30 seconds in between sonications. To prepare a filtrate extract for the immunoassay, use a 10 milliliter syringe coupled to a five to 20 micron pore size nylon filter holder to filter the solution into a 1.5 milliliter tube to remove sand, clay and other coarse material.With the microarray spots facing down, lay the slide onto a 100 to 200 microliter drop of blocking solution and incubate for three to five minutes. Using plastic-tipped forceps, and avoiding the microarray zones, carefully pick up the slide. Immerse the slide into a fresh blocking solution and incubate the slide with mild agitation for 30 minutes.To dry the slide, place it in a centrifuge adapted for microscope slides and briefly spin it. Set up the slide in a three by eight well microarray hybridization cassette following the provider's instructions. Alternatively, after modifying the antibody printing pattern, set up a custom-made cassette, such as the one shown here, or simply use cover slides for the setup.Following slide and cassette assembly, pipette up to 50 microliters of each sample extract or dilution of it in extraction incubation buffer into each well of the cassette. Alternatively, load samples into other incubation devices or simply use cover slides. As a blank control, pipette 50 microliters of TBSTRR buffer into at least two separate wells of the cassette.Incubate the samples at ambient temperature for one hour and mix by pipetting every 15 minutes, or incubate at four degrees Celsius for 12 hours. To wash the microarrays, place the cassette down and carefully tap it onto clean absorbent paper. Then wash the wells by adding 150 microliters of extraction incubation buffer to each one and remove the buffer by tapping on absorbent paper as before.Repeat the wash three more times. To each well, add 50 microliters of the fluorescent antibody mixture that contains the 17 anti-cyanobacterial strain antibodies. Incubate the samples at ambient temperature for one hour or at four degrees Celsius for 12 hours.To wash the microarrays, carefully place the cassette down and gently tap it onto clean absorbent paper. Then add 150 microliters of extraction incubation buffer before removing it by tapping onto a paper towel. Repeat the wash three times.Then disassemble the cassette and immerse the slide in 0.1X PBS solution for a quick rinse. Quickly centrifuge as before to dry the slide. Using a fluorescent scanner, scan the slide for fluorescence at the maximum emission peak for far red fluorescent dye.Take several images of the microarrays at different scanning parameters by changing the gain value. Finally, load the grid, quantify, then process and analyze the data according to the text protocol. The CYANOCHIP multiplex immunoassay demonstrated in this video, was used to test for the simultaneous identification of the most relevant freshwater cyanobacterial species as listed in this table.Water samples collected at the shore of a freshwater reservoir, were analyzed using the microarray assay. The main positive immuno reactions corresponded to antibodies to planktonic cyanobacteria microcystis species and to the benthic leptolyngbya species. Lower fluorescent signals were obtained for planktonic nostocales aphanizomenon species, anabaena species, microcystis flos-aquae and the benthic rivularia species.The microarray was also validated by assaying an antarctic dry microbial mat to test for the presence of cyanobacterial markers. Positive reactions in the antibodies were produced to the benthic cyanobacteria, anabaena species and leptolyngbya species. Additional positive immuno reactions were detected with antibodies to planktonic cyanobacteria, such as microcystis species, aphanizomenon species and planktothrix rubescens species.Finally, those signals were obtained from antibodies to other benthic species, including tolypothrix species and anabaena species. Once mastered, this technique can be done in three, four hours, if it is performed properly, excluding antibody production and leveling. By simultaneous incubation of sample, and fluorescent antibodies, it can be save one hour.While attempting these procedures, it is important to remember to get the fluorescent antibody mixture ready with its antibody at its optimal working dilution. Following these procedures, other methods, like optical microscopy or DNA extraction and a specific PCR amplification, can be perform in order to answer additional questions, like the soil concentration or to confirm the type of strain detected. After its development, this technique will pave the way for researchers in the field of environmental monitoring to explore water bodies, in a biculture processes, fresh water management or microbial ecology studies, regardless of the type of the sample.After watching this video, you should have a good understanding of how to label antibodies with fluorescence, manipulate antibody microarrays, perform multiplex immunoassay and analyze and interpret microarray immunoassay results. Don't forget that working with ultrasounds can hazardous and precautions such as wearing ear-protection devices or other specific care measures should always be taken while performing these procedures.

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9.0K vues.  Centro de Astrobiología (CAB, INTA-CSIC). The overall goal of this procedure is to determine the presence of multiple cyanobacterial strains in liquid and solid samples using a fluorescence microarray immunoassay. This method can help answer key questions in the environmental, monitoring and water management fields, such as the presence of toxins produced protoxin-producing bacteria before the blooms become visible to the naked eyes. The main advantage of this technique is that multiple cyanobacterial strains and multiple samples can...