Name: an efficient method for the isolation of highly purified rna from seeds for use in quantitative transcriptome analysis
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Description: Watch this Scientific Journal Video about An Efficient Method for the Isolation of Highly Purified RNA from Seeds for Use in Quantitative Transcriptome Analysis at JoVE.com

We thank the staff of Functional Genomics Facility and&#160; Spectrography and Bioimaging Facility, NIBB Core Research Facilities, and Model Plant Research Facility, NIBB Bioresource Center.

1. Extraction of Total RNA from Plant Seeds
<ol>
	<li>Prepare buffer sets, spin columns, 1.5 and 2.0 mL polypropylene tubes, and nuclease-free 1.5 mL polypropylene tubes.</li>
	<li>Add 1% (w/v) molecular biology grade polyvinylpyrrolidone (hereafter referred to as PVP) to cell lysis buffer for RNA extraction and vortex vigorously. Incubate for 20 min at 25 &#176;C to dissolve completely. After 20 min incubation, mix the buffer gently by turning the tube upside down to prevent the formation of bubbles. Store at room tem...

<ol>
	<li>Hills, M. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Control+of+storage-product+synthesis+in+seeds.">Control of storage-product synthesis in seeds.</a> Curr Opin Plant Biol. 7 (3), 302-308 (2004).</li><li>Li-Beisson, Y., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Acyl-lipid+metabolism.">Acyl-lipid metabolism.</a> Arabidopsis Book. 11, e0161 (2013).</li><li>Bates, P. D., Stymne, S., Ohlrogge, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Biochemical+pathways+in+seed+oil+synthesis.">Biochemical pathways in seed oil synthesis.</a> Curr Opin Plant Biol. 16 (3), 358-364 (2013).</li><li>Santos-Mendoza, M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Deciphering+gene+regulatory+networks+that+control+seed+development+and+maturation+in+Arabidopsis.">Deciphering gene regulatory networks that control seed development and maturation in Arabidopsis.</a> Plant J. 54 (4), 608-620 (2008).</li><li>Durrett, T. P., Benning, C., Ohlrogge, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Plant+triacylglycerols+as+feedstocks+for+the+production+of+biofuels.">Plant triacylglycerols as feedstocks for the production of biofuels.</a> Plant J. 54 (4), 593-607 (2008).</li><li>Kanai, M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+Plastidic+DEAD-box+RNA+helicase+22,+HS3,+is+essential+for+plastid+functions+both+in+seed+development+and+in+seedling+growth.">The Plastidic DEAD-box RNA helicase 22, HS3, is essential for plastid functions both in seed development and in seedling growth.</a> Plant Cell Physiol. 54 (9), 1431-1440 (2013).</li><li>Kanai, M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Extension+of+oil+biosynthesis+during+the+mid-phase+of+seed+development+enhances+oil+content+in+Arabidopsis+seeds.">Extension of oil biosynthesis during the mid-phase of seed development enhances oil content in Arabidopsis seeds.</a> Plant Biotechnol J. 14 (5), 1241-1250 (2016).</li><li>Dekkers, B. J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Identification+of+reference+genes+for+RT-qPCR+expression+analysis+in+Arabidopsis+and+tomato+seeds.">Identification of reference genes for RT-qPCR expression analysis in Arabidopsis and tomato seeds.</a> Plant Cell Physiol. 53 (1), 28-37 (2012).</li><li>Salzman, R. A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=An+improved+RNA+isolation+method+for+plant+tissues+containing+high+levels+of+phenolic+compounds+or+carbohydrates.">An improved RNA isolation method for plant tissues containing high levels of phenolic compounds or carbohydrates.</a> Plant Mol Biol Rep. 17 (1), 11-17 (1999).</li><li>Vicient, C. M., Delseny, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Isolation+of+total+RNA+from+Arabidopsis+thaliana+seeds.">Isolation of total RNA from Arabidopsis thaliana seeds.</a> Anal Biochem. 268 (2), 412-413 (1999).</li><li>Wang, G. F., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Isolation+of+high+quality+RNA+from+cereal+seeds+containing+high+levels+of+starch.">Isolation of high quality RNA from cereal seeds containing high levels of starch.</a> Phytochem Analysis. 23 (2), 159-163 (2012).</li><li>Birtic, S., Kranner, I. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Isolation+of+high-quality+RNA+from+polyphenol-,+polysaccharide-+and+lipid-rich+seeds.">Isolation of high-quality RNA from polyphenol-, polysaccharide- and lipid-rich seeds.</a> Phytochem Analysis. 17 (3), 144-148 (2006).</li></ol>

Gene expression profiles contribute to our understanding of plant physiology; therefore, specific RNA isolation methods have been developed for each sample condition9-12. We investigated the processes that were inhibited during RNA isolation from seeds and found that RNA binding to silica membranes was severely inhibited. Large amounts of oil, proteins, and polyphenols inhibit RNA isolation. We modified the RNA extraction process to remove these compounds with a lysis solution before the process of RNA binding...

Plants produce seeds, which give rise to the next generation. Seeds accumulate large amounts of storage reserves, such as oils, carbohydrates, and proteins, for post-germinative growth. Humans utilize seed storage reserves as sources of food and animal feed, and thus plant seeds are one of the major suppliers of edible organic matter worldwide. Increasing seed yields is an important challenge in plant science.
Since seed storage reserves are commercially valuable sources of food and industrial materials, the molecular mechanisms underlying the regulation of the metabolism of these reserves have been widely investigated1-6. Further elucidating these mechanisms will be useful for increasing seed yields in crops. Seeds develop in plant ovaries after fertilization, and they mature through a series of developmental stages1,6,7. Further understanding the molecular mechanism underlying seed development requires detailed, precise gene expression profiles from a series of developing seeds to be produced. However, the high amounts of oils, proteins, carbohydrates, and polyphenols in plant seeds make it difficult to isolate highly purified RNA, which precludes precise profiling of gene expression.
Here, we introduce an efficient method for RNA isolation from oilseeds containing large amounts of oils, proteins, and polyphenols. Using this method, researchers will be able to prepare highly purified RNA. Such RNA will be useful for monitoring transcriptional changes in key genes controlling the metabolic regulation of seed storage reserves in developing and mature oilseeds.

<table border="0" cellpadding="0" cellspacing="0" width="655">
	<tbody>
		<tr height="21">
			<td height="21" style="height:21px;width:247px;">RNeasy Plant Mini Kit</td>
			<td style="width:81px;">QIAGEN</td>
			<td style="width:136px;">74904</td>
			<td style="width:191px;"></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:247px;">polyvinylpyrrolidone</td>
			<td style="width:81px;">Sigma-Aldrich</td>
			<td style="width:136px;">P5288-100G</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:247px;">HOMOGENIZER S-303</td>
			<td style="width:81px;">AS ONE</td>
			<td style="width:136px;">1-1133-02</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:247px;">NanoDrop Lite</td>
			<td style="width:81px;">Thermo Scientific</td>
			<td style="width:136px;">ND-NDL-US-CAN</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:247px;">PrimeScript RT reagent Kit (Perfect Real Time)</td>
			<td style="width:81px;">TAKARA</td>
			<td style="width:136px;">RR037A</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:247px;">KAPA SYBR Fast qPCR kit</td>
			<td style="width:81px;">Kapa biosystems</td>
			<td style="width:136px;">KK4601</td>
			<td></td>
		</tr>
	</tbody>
</table>

an efficient method for the isolation of highly purified rna from seeds for use in quantitative transcriptome analysis

Plant seeds accumulate large amounts of storage reserves comprising biodegradable organic matter. Humans rely on seed storage reserves for food and as industrial materials. Gene expression profiles are powerful tools for investigating metabolic regulation in plant cells. Therefore, detailed, accurate gene expression profiles during seed development are required for crop breeding. Acquiring highly purified RNA is essential for producing these profiles. Efficient methods are needed to isolate highly purified RNA from seeds. Here, we describe a method for isolating RNA from seeds containing large amounts of oils, proteins, and polyphenols, which have inhibitory effects on high-purity RNA isolation. Our method enables highly purified RNA to be obtained from seeds without the use of phenol, chloroform, or additional processes for RNA purification. This method is applicable to Arabidopsis, rapeseed, and soybean seeds. Our method will be useful for monitoring the expression patterns of low level transcripts in developing and mature seeds.

We first investigated the optimal concentration of PVP using Arabidopsis mature seeds. Total RNA was isolated from approximately 1,000 seeds according to the protocol described above using cell lysis buffer containing 0%, 0.25%, 0.5%, 1.0% or 2.0% PVP. After homogenization and centrifugation, the supernatant was collected while avoiding the oil layer and seed debris (Figure 1A).
<img alt="Figure 1" src=...

Watch this Scientific Journal Video about An Efficient Method for the Isolation of Highly Purified RNA from Seeds for Use in Quantitative Transcriptome Analysis at JoVE.com

An Efficient Method for the Isolation of Highly Purified RNA from Seeds for Use in Quantitative Transcriptome Analysis

We have succeeded in establishing a method for RNA isolation from plant seeds containing large amounts of oils, proteins, and polyphenols, which have inhibitory effects on high-purity RNA isolation. Our method is suitable for monitoring the expression of genes with low level transcripts in seeds.

Plant seeds accumulate large amounts of storage reserves comprising biodegradable organic matter. Humans rely on seed storage reserves for food and as ...

The overall goal of this procedure is to extract high purity RNA from plant seeds. This method can help answer key questions in the cereal biology field, such as understanding gene profiles, containing the original transcripts in seeds. The main advantage of this technique is that researchers are able to prepare high-purified RNA with slight modification to the spin column-based method.Generally, individuals new to this method will struggle because the high amount of oils, proteins, carbohydrates and polyphenols in front sieve make it difficult to isolate highly purified RNA;demonstrating the procedure will be Kazumi Hikino, a technician from our laboratory. To begin the experiment, add one percent weight per volume molecular biology grade PVP to cell lysis buffer for RNA extraction, and vortex the mixture vigorously. Incubate the PVP for 20 minutes at 25 degrees celsius to dissolve it completely.After 20 minutes of incubation, mix the buffer gently by turning the tube upside down to prevent bubbles from forming. Harvest fruits from Arabidopsis thaliana plants and place them into two 1.5 millimeter polypropylene tubes on ice, then place the fruits on aluminum plates kept at four degrees celsius and isolate seeds from the fruits under a stereo microscope. Next, place approximately 200 isolated seeds into 1.5 milliliter polypropylene tubes that have been previously stored in an aluminum rack on ice, and immediately place the tubes in liquid nitrogen.Remove the tubes from the liquid nitrogen and return them to the aluminum rack on ice. Add 100 microliters of the one percent PVP buffer to each tube and centrifuge the tubes for one minute at 1000 times G, at four degrees celsius. After centrifugation, homogenize the sample with a stainless steel pestle using a motor grinder for 60 seconds while keeping the tube in the aluminum rack on ice;next, add 550 microliters of the 100%PVP buffer and gently turn the tube upside down to mix and incubate the tube.After incubation, centrifuge the solution then transfer 550 microliters of the supernatant to a new 1.5 millimeter polypropylene tube and centrifuge the supernatant. Transfer 450 microliters of the supernatant to a new 1.5 millimeter polypropylene tube. Use the supernatant as the cell lysate for RNA extraction using a commercially available kit.Prepare an aluminum rack on ice, and thaw the total RNA mix by gently tapping, then place the tube on the rack. Measure the RNA concentration using a microvolume spectrophotometer. Then dilute the total RNA in RNase-free water.Thaw the total RNA and buffer sets from the commercial kit, keep the enzymes from the kit on ice after gentle tapping. Prepare sterilized nuclease free 0.2 milliliter polypropylene tubes for subsequent analysis. On ice, combine five microliters of total RNA, one microliter or 50 micromolar of oligo DT primer and one microliter, or 50 micromolar random six-mer in the 0.2 milliliter polypropylene tube.Incubate the mixture for 15 minutes at 37 degrees celsius, then place the tube on ice. Adjust the plasmid concentrations for DNA templates for the standard curves. Next, dilute the CDNA solutions at one to 100 with distilled water, then add two microliters of the diluted CDNA solutions and the previously prepared plasmids for the standard curves to the master mix from the quantitative realtime PCR kit.Finally, set up the realtime PCR and insert the samples. Total RNA was isolated from approximately 1, 000 seeds using varying concentrations of cell lysis buffer, PVP. The quantities and purity of the isolated RNAs demonstrate that 1.0%PVP is the most effective concentration to isolate large amounts of purified RNA from seeds.The concentrations, A260 and A280 ratios, and A260 A230 ratios of RNA isolated from 200 seeds showed that this method was best at isolating highly-purified RNA from eight and 12 days after flowering, or DAF seeds. Although the amounts of wrinkled one and sugar-dependent one transcripts are relatively low in developing seeds, it was possible to detect expression changes between seeds at different developmental stages via realtime PCR;this method is also suitable for other oil seeds, as demonstrated in this table. After its development, this technique paved the way for researchers in the field of plant biology to explore gene expression profiles in high concentration of stored reserves, such as seeds and fruits.

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Biochemistry

Isolation of High-density Lipoproteins for Non-coding Small RNA Quantification

The diversity of small non-coding RNAs (sRNA) is rapidly expanding and their roles in biological processes, including gene regulation, are emerging. Most interestingly, sRNAs are also found outside of cells and are stably present in all biological fluids. As such, extracellular sRNAs represent a novel class of disease biomarkers and are likely involved in cell signaling and intercellular communication networks. To assess their potential as biomarkers, sRNAs can be quantified in plasma, urine, and other fluids. Nevertheless, to fully understand the impact of extracellular sRNAs as endocrine signals, it is important to determine which carriers are transporting and protecting them in biological fluids (e.g., plasma), which cells and tissues contribute to extracellular sRNA pools, and cells and tissues capable of accepting and utilizing extracellular sRNA. To accomplish these goals, it is critical to isolate highly pure populations of extracellular carriers for sRNA profiling and quantification. We have previously demonstrated that lipoproteins, particularly high-density lipoproteins (HDL), transport functional microRNAs (miRNA) between cells and HDL-miRNAs are significantly altered in disease. Here, we detail a new protocol that utilizes tandem HDL isolation with density-gradient ultracentrifugation (DGUC) and fast-protein-liquid chromatography (FPLC) to obtain highly pure HDL for downstream profiling and quantification of all sRNAs, including miRNAs, using both high-throughput sequencing and real-time PCR approaches. This protocol will be a valuable resource for the investigation of sRNAs on HDL.

This protocol describes the isolation and quantification of high-density lipoprotein small RNAs.

The diversity of small non-coding RNAs (sRNA) is rapidly expanding and their roles in biological processes, including gene regulation, are emerging. Most ...

An Efficient Method for the Synthesis of Peptoids with Mixed Lysine-type/Arginine-type Monomers and Evaluation of Their Anti-leishmanial Activity

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A protocol to synthesize peptoids with mixed cationic functionality in the same sequence is presented (lysine- and arginine-type monomers). Subsequent testing of these compounds against Leishmania mexicana, the protozoan parasites that cause cutaneous leishmaniasis, is also described.

This protocol describes the manual solid-phase synthesis of linear peptoids that contain two differently functionalized cationic monomers. In this ...

Experimental Design for Laser Microdissection RNA-Seq: Lessons from an Analysis of Maize Leaf Development

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Many developmentally important genes have cell- or tissue-specific expression patterns. This paper describes LM RNA-seq experiments to identify genes that are differentially expressed at the maize leaf blade-sheath boundary and in lg1-R mutants compared to wild-type. The experimental considerations discussed here apply to transcriptomic analyses of other developmental phenomena.

Genes with important roles in development frequently have spatially and/or temporally restricted expression patterns. Often these gene transcripts are not ...

Lipid Droplet Isolation for Quantitative Mass Spectrometry Analysis

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Lipid droplets are important organelles for the replication of several pathogens, including the Hepatitis C Virus (HCV). We describe a method to isolate lipid droplets for quantitative mass spectrometry of associated proteins; it can be used under a variety of conditions, such as virus infection, environmental stress, or drug treatment.

Lipid droplets are vital to the replication of a variety of different pathogens, most prominently the Hepatitis C Virus (HCV), as the putative site of ...

Highly Sensitive and Quantitative Detection of Proteins and Their Isoforms by Capillary Isoelectric Focusing Method

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Capillary isoelectric focusing is an antibody-based, ultrasensitive, high throughput technique, enabling detailed characterization of proteins and their isoforms from extremely small biological samples. The following describes a protocol for detection and quantification of specific proteins and their isoforms in an automated and robotized manner.

Immunoblotting has become a routine technique in many laboratories for protein characterization from biological samples. The following protocol provides ...

A Colorimetric Method for Measuring Iron Content in Plants

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We present a simple and reliable protocol for measuring iron content in plant tissues using the colorimetric Prussian Blue method.

Iron, one of the most important micronutrients in living organisms, is involved in basic processes, such as respiration and photosynthesis. Iron content ...

Toeprinting Analysis of Translation Initiation Complex Formation on Mammalian mRNAs

Translation initiation is the rate-limiting step of protein synthesis and represents a key point at which cells regulate their protein output. Regulation of protein synthesis is the key to cellular stress-response, and dysregulation is central to many disease states, such as cancer. For instance, although cellular stress leads to the inhibition of global translation by attenuating cap-dependent initiation, certain stress-response proteins are selectively translated in a cap-independent manner. Discreet RNA regulatory elements, such as cellular internal ribosome entry sites (IRESes), allow for the translation of these specific mRNAs. Identification of such mRNAs, and the characterization of their regulatory mechanisms, have been a key area in molecular biology. Toeprinting is a method for the study of RNA structure and function as it pertains to translation initiation. The goal of toeprinting is to assess the ability of in vitro transcribed RNA to form stable complexes with ribosomes under a variety of conditions, in order to determine which sequences, structural elements, or accessory factors are involved in ribosome binding&#8212;a pre-cursor for efficient translation initiation. Alongside other techniques, such as western analysis and polysome profiling, toeprinting allows for a robust characterization of mechanisms for the regulation of translation initiation.

Toeprinting aims to measure the ability of in vitro transcribed RNA to form translation initiation complexes with ribosomes under a variety of conditions. This protocol describes a method for toeprinting mammalian RNA and can be used to study both cap-dependent and IRES-driven translation.

Translation initiation is the rate-limiting step of protein synthesis and represents a key point at which cells regulate their protein output. Regulation ...

Rapid Isolation of the Mitoribosome from HEK Cells

The human mitochondria possess a dedicated set of ribosomes (mitoribosomes) that translate 13 essential protein components of the oxidative phosphorylation complexes encoded by the mitochondrial genome. Since all proteins synthesized by human mitoribosomes are integral membrane proteins, human mitoribosomes are tethered to the mitochondrial inner membrane during translation. Compared to the cytosolic ribosome the mitoribosome has a sedimentation coefficient of 55S, half the rRNA content, no 5S rRNA and 36 additional proteins. Therefore, a higher protein-to-RNA ratio and an atypical structure make the human mitoribosome substantially distinct from its cytosolic counterpart.
Despite the central importance of the mitoribosome to life, no protocols were available to purify the intact complex from human cell lines. Traditionally, mitoribosomes were isolated from mitochondria-rich animal tissues that required kilograms of starting material. We reasoned that mitochondria in dividing HEK293-derived human cells grown in nutrient-rich expression medium would have an active mitochondrial translation, and, therefore, could be a suitable source of material for the structural and biochemical studies of the mitoribosome. To investigate its structure, we developed a protocol for large-scale purification of intact mitoribosomes from HEK cells. Herein, we introduce nitrogen cavitation method as a faster, less labor-intensive and more efficient alternative to traditional mechanical shear-based methods for cell lysis. This resulted in preparations of the mitoribosome that allowed for its structural determination to high resolution, revealing the composition of the intact human mitoribosome and its assembly intermediates. Here, we follow up on this work and present an optimized and more cost-effective method requiring only ~1010 cultured HEK cells. The method can be employed to purify human mitoribosomal translating complexes, mutants, quality control assemblies and mitoribosomal subunits intermediates. The purification can be linearly scaled up tenfold if needed, and also applied to other types of cells.

Mitochondria have specialized ribosomes that diverged from their bacterial and cytoplasmic counterparts. Here we show how mitoribosomes can be obtained from their native compartment in HEK cells. The method involves isolation of mitochondria from suspension cells and consequent purification of mitoribosomes.

The human mitochondria possess a dedicated set of ribosomes (mitoribosomes) that translate 13 essential protein components of the oxidative ...

Translating Ribosome Affinity Purification (TRAP) for RNA Isolation from Endothelial Cells In Vivo

Many studies have been limited to using in vitro cellular assays and whole tissues or isolating of specific cell types from animals for in vitro analysis of transcriptome and gene expression by qPCR and RNA sequencing. Comprehensive transcriptome and gene expression analysis of specific cell types in complex tissues and organs will be critical to understand cellular and molecular mechanisms by which genes are regulated and their association with tissue homeostasis and organ functions. In this article, we demonstrate the methodology for isolation of ribosome-bound RNA directly in vivo in the vascular endothelia of animal lungs as an example. The specific materials and procedures for tissue processing and RNA purification will be described, including the assessment of RNA quality and yield as well as real time qPCR for arteriogenic gene assays. This approach, known as translating ribosome affinity purification (TRAP) technique, can be utilized for characterization of gene expression and transcriptome analysis of certain cell types directly in vivo in any specific type in complex tissues.

Translating Ribosome Affinity Purification TRAP for RNA Isolation from Endothelial Cells In Vivo

We present an approach to purify ribosome-bound mRNA from vascular endothelial cells (ECs) directly in mouse brain, lung and heart tissues via EC-specific genetic tag of enhanced green fluorescence protein (EGFP)in ribosomes in combination with RNA purification.

Many studies have been limited to using in vitro cellular assays and whole tissues or isolating of specific cell types from animals for in vitro analysis ...

Obtaining High-Quality Transcriptome Data from Cereal Seeds by a Modified Method for Gene Expression Profiling

The characterization of gene expression is dependent on RNA quality. In germinating, developing and mature cereal seeds, the extraction of high-quality RNA is often hindered by high starch and sugar content. These compounds can reduce both the yield and the quality of the extracted total RNA. The deterioration in quantity and quality of total RNA can subsequently have a significant impact on the downstream transcriptomic analyses, which may not accurately reflect the spatial and/or temporal variation in the gene expression profile of the samples being tested. In this protocol, we describe an optimized method for extraction of total RNA with sufficient quantity and quality to be used for whole transcriptome analysis of cereal grains. The described method is suitable for several downstream applications used for transcriptomic profiling of developing, germinating, and mature cereal seeds. The method of transcriptome profiling using a microarray platform is shown. This method is specifically designed for gene expression profiling of cereals with described genome sequences. The detailed procedure from microarray handling to final quality control is described. This includes cDNA synthesis, cRNA labelling, microarray hybridization, slide scanning, feature extraction, and data quality validation. The data generated by this method can be used to characterize the transcriptome of cereals during germination, in various stages of grain development, or at different biotic or abiotic stress conditions. The results presented here exemplify high-quality transcriptome data amenable for downstream bioinformatics analyses, such as the determination of differentially expressed genes (DEGs), characterisation of gene regulatory networks, and conducting transcriptome-wide association study (TWAS).

A method for transcriptome profiling of cereals is presented. The microarray-based gene expression profiling starts with the isolation of high-quality total RNA from cereal grains and continues with the generation of cDNA. After cRNA labelling and microarray hybridization, recommendations are given for signal detection and quality control.

The characterization of gene expression is dependent on RNA quality. In germinating, developing and mature cereal seeds, the extraction of high-quality ...