Profiling gene expression in whole blood samples following an in-vitro challenge.

Genomics tools (gene- and protein-expression studies) can be used to find possible target genes involved in a quantifiable trait or disease state. However in many instances, cells and tissues directly involved in the trait's expression, for example, brain tissue, are not amenable for gene expression analysis. Whole blood cells share a molecular make-up for cellular communication and gene regulation systems with many other cell types, for example, neuronal cells, and have the advantage of being very accessible for gene profiling. We investigated the feasibility of nationwide blood sample collection for lymphocyte RNA isolation and real-time PCR analysis to quantify genomic responses. We tested several designs for blood collection and storage: blood sampling in PAXgene blood collection tubes and storage at -20 degrees C, blood sampling in heparin tubes and decanting the samples (with or without in-vitro stimulus) into either PAXgene blood collection tubes and storage at -20 degrees C, or polypropylene tubes followed by snap-freezing and storage at -80 degrees C. The latter procedure is the best cost-wise when only small amounts of total RNA are needed for downstream applications. Lymphocyte gene expression studies are most likely hampered by the quality of isolated RNA rather than the sampling method. We show that large-scale nationwide sample collections did not alter RNA quality or gene expression levels when compared to sampling and processing in a more controlled way. To this end, we present an optimized protocol for easy and standardized isolation of high quality RNA using the PAXgene isolation kit. Based on these results, we suggest that whole blood genomic data can be used as a genomic probe in experimental and clinical research.     

A Modified Protocol for RNA Extraction from Different Peach Tissues Suitable for Gene Isolation and Real-Time PCR Analysis

RNA extraction is the first step in the study of gene isolation and expression. However, it is difficult to extract high quantity and quality RNA from tissues containing large quantities of polysaccharides and polyphenols. Peach (Prunus persica), in addition to containing high levels of polysaccharides and polyphenols, is a challenging starting material for RNA isolation using a single method because of different amounts of those substances in diverse tissues. Based on three reported methods, we developed a modified RNA isolation protocol to solve this problem, leading to high quality and quantity of total RNA from peach mesocarp tissues of fruits which were sampled from all developmental stages and different storage periods, as well as from other tissues including flowers, leaves, stems, and roots. With our modified method, 28–650 μg of total RNA was routinely obtained from per gram of fresh material, gave at least a 1.16-fold improvement by compared with those isolated by other seven methods. The RNA extracts were successfully used in downstream applications such as RT-PCR, RACE, and real-time PCR.     

Total RNA content in sheep oocytes and developing embryos produced in vitro,a comparative study between spectrophotometric and fluorometric assay

Isolation of total RNA from limited number of oocytes and embryos is a big challenge. DNA free RNA and assessment of RNA integrity are crucial to the success of gene expression studies because poor quality RNA give misleading results. The objective of the present study was to establish a suitable protocol to isolate good quality total RNA from a minimal number of sheep oocytes and embryos that enables the downstream applications, as well as to estimate RNA content in oocytes and developmental stages of embryos. Five protocols were approached to isolate total RNA from oocytes and embryos. Four methods were by standard Trizol protocols and its modification whereas fifth method was by commercial kit (RNeasy mini kit, Quiagen). Total RNA isolated by modified Trizol protocol with coprecipitants (acrylamide and glycogen) showed significantly (P < 0.05) more spectrophotometric reading of RNA concentration than by modified Trizol protocol without coprecipitant followed by commercial kit and conventional Trizol protocol. RNA quality, purity, concentration, RNA per oocyte and expression of GAPDH (house keeping gene) were compared to find the best RNA isolated by different protocols. Spectrophotometric and fluorometric assay were compared to quantify the total RNA concentration in sheep oocytes and different stages of developing embryos. RNA yield by spectrophotometer analysis showed 5–100 times more reading than fluorometer. Significant (P < 0.05) reduction in RNA content was observed in matured oocytes than that of immature oocytes. There was significant (P < 0.05) increase in RNA content after fertilization upto 2–4 cells stage followed by significant (P < 0.05) decrease at 8–16 cells and increased at morula. RNA concentration at blastocyst was significantly low than at morula. From the protocols approached modified Trizol protocol with coprecipitant was most efficient and suitable method over other protocols approached to isolate RNA from few sheep oocytes and embryos for gene expression study.     

Comparison of DNA extraction methods for PCR amplification of mitochondrial cytochrome c oxidase subunit II (COII) DNA from primate fecal samples

Mitochondrial COII DNA was amplified by PCR from total DNA extracted from field collected primate fecal samples (n=24) which had been stored without refrigeration for over 30 days. High molecular weight DNA total DNA was obtained from samples stored in 70% (v/v) ethanol, SDS lysis buffer (LB) and guanidine isothiocyanate buffer (GTB) than from samples stored in 10% formalin. Fecal DNA quality and COII amplification varied according to storage solution (formalin, ethanol, LB and GTB), extraction method (LB-based and GTB-based) and primate species (chimpanzee, baboon, human). It is recommended that fecal samples be collected in LB for DNA analysis. However, GTB-based protocols are suitable when total RNA is needed for epidemiological studies of viral diseases or gene expression analysis.     

Enhanced sensitivity RNA gel loading buffer that enables efficient RNA separation on native gels

RNA gel analysis is essential for quality assessment of RNA preparations for subsequent analysis such as microarrays and real-time PCRs. The routinely used standard electrophoresis of RNA through formaldehyde-containing agarose gels is not only labor-intensive and time-consuming, but also involves sizeable quantities of hazardous materials. Above all, it is not sensitive, requiring more than 1 microgram of RNA for the assay. Current gene expression profiling with microarrays and real-time PCR often involves limiting amounts of RNA. It is therefore important to have a more sensitive way to analyze RNA. Here we report an improved ethidium bromide-based RNA gel analysis system with our Superload buffer that increases sensitivity to 12.5 ng of total RNA and allows RNA analysis on a regular native Tris-acetate EDTA (TAE) agarose gel.     

从少量转染细胞中同时快速提取总RNA和基因组DNA

采用4mol / L LiCl将DNA和RNA分相,建立了同时从少量转染细胞中快速提取细胞总RNA和大分子基因组DNA的方法.与以前的方法相比,本法快速、简便、经济,尤其适合应用在哺乳动物细胞基因表达与调控的研究中．     

Optimized procedures for microarray analysis of histological specimens processed by laser capture microdissection

Analysis of cell-specific gene expression patterns using microarrays can reveal genes that are differentially expressed in diseased and normal tissue, as well as identify genes associated with specialized cellular functions. However, the cellular heterogeneity of the tissues precludes the resolution of expression profiles of specific cell types. While laser capture microdissection (LCM) can be used to obtain purified cell populations, the limited quantity of RNA isolated makes it necessary to perform an RNA amplification step prior to microarray analysis. The linearity and reproducibility of two RNA amplification protocols--the Baugh protocol (Baugh et al., 2001, Nucleic Acids Res 29:E29) and an in-house protocol have been assessed by conducting microarray analyses. Cy3-labeled total RNA from the colorectal cell line Colo-205 was compared to Cy5-labeled Colo-205 amplified RNA (aRNA) generated with each of the two protocols, using a human 10K cDNA array. The correlation of the gene intensities between amplified and total RNA measured in the two channels of each microarray was 0.72 and 0.61 for the Baugh protocol and the in-house protocol, respectively. The two protocols were further evaluated using aRNA obtained from normal colonic crypt cross-sections isolated via LCM. In both cases a microarray profile representative of colonic mucosa was obtained; statistically, the Baugh protocol was superior. Furthermore, a substantial overlap between highly expressed genes in the Colo-205 cells and colonic crypts underscores the reliability of the microarray analysis of LCM-derived material. Taken together, these results demonstrate that LCM-derived tissue from histological specimens can generate abundant amounts of high-quality aRNA for subsequent microarray analysis.     

A convenient and efficient protocol for isolating high-quality RNA from latex of Hevea brasiliensis (para rubber tree)

Isolating high-quality RNA from latex of H. brasiliensis is a prerequisite to elucidating the molecular mechanisms of rubber biosynthesis and its regulation. Here, an improved protocol was developed for latex collection, transportation, storage, and RNA isolation. Compared with existing ones, our protocol eliminated liquid nitrogen for latex collection and subsequent low-temperature (-70 degrees C) condition for latex storage, making it more convenient and feasible when latex was collected in remote sampling sites, and latex storage and RNA isolation were conducted in poorly-equipped laboratories. Different methods (UV absorbance scans, denaturing gel electrophoresis, autoradiograph monitoring of cDNA synthesis) were used to confirm the high quality of the RNA prepared with this protocol, whose usefulness was further verified by several practical applications, including construction of one high-quality cDNA library, cloning of the full-length cDNAs of 3 novel Hevea sucrose transporter genes, and semi-quantitative RT-PCR analysis of two rubber-biosynthesis essential genes and one sucrose transporter gene.     

Evaluation of procedures for amplification of small-size samples for hybridization on microarrays

Various approaches have been developed for the preparation of samples for gene expression monitoring. For Affymetrix chips, a standard protocol is widely used; however, this is inefficient for small samples such as laser capture microdissections. Several amplification procedures for such samples already exist, and our goal was to test two of them: the first is based on random PCR amplification, and the second, linear amplification, involves performing the standard protocol twice. We analyzed a dilution of a commercially available mouse brain total RNA preparation and microdissections from mouse hippocampus and striatum. We evaluated the quality of microarray data by analyzing several chip parameters and performing multiple comparisons. At the biological level, brain microdissections prepared with either method gave similar expression results. At the technical level, analysis of the commercial sample showed that random PCR amplification is more reproducible, requires smaller RNA input, and generates cRNA of higher quality than linear amplification.     

RNA extraction from various recalcitrant plant tissues with a cethyltrimethylammonium bromide-containing buffer followed by an acid guanidium thiocyanate-phenol-chloroform treatment

High-quality total RNA was extracted using a cethyltrimethylammonium bromide-containing buffer followed by an acid guanidium thiocyanate-phenol-chloroform treatment from recalcitrant plant tissues such as tree leaves (pine, Norway spruce, ginkgo, Japanese cedar, rose), flowers (rose, Lotus japonicus) and storage tissues (seeds of Lotus japonicus and rice, sweet potato tuber, banana fruit). This protocol greatly reduced the time required for RNA extraction.     

Effects of mRNA amplification on gene expression ratios in cDNA experiments estimated by analysis of variance

Background  

A limiting factor of cDNA microarray technology is the need for a substantial amount of RNA per labeling reaction. Thus, 20–200 micro-grams total RNA or 0.5–2 micro-grams poly (A) RNA is typically required for monitoring gene expression. In addition, gene expression profiles from large, heterogeneous cell populations provide complex patterns from which biological data for the target cells may be difficult to extract. In this study, we chose to investigate a widely used mRNA amplification protocol that allows gene expression studies to be performed on samples with limited starting material. We present a quantitative study of the variation and noise present in our data set obtained from experiments with either amplified or non-amplified material.     

一种用于基因芯片可靠的双轮RNA线性扩增技术

DNA微阵列能在一次实验中检测成千上万个基因的表达情况, 有助于阐明疾病发生的分子机制及发现新的诊治靶标.但常规方法需要大量RNA, 因而基于T7 RNA线性扩增技术逐渐成为微阵列表达谱实验中最常用的探针制备方法.本方法将实验步骤进一步改进,增加额外的一轮体外转录,并结合Klenow酶标记技术来制备cDNA靶标和寡核苷酸芯片杂交.从纳克量级的总RNA起始,本方法和常规的RNA单轮线性扩增法相比,仍然准确地保留了约70%的基因表达信息.同一RNA样本的自身比较实验及重复实验结果也显示,该方法具有较高的可靠性和重复性.RNA双轮体外扩增法需要的起始RNA相对于常规的单轮扩增法减少了很多（10 ng甚至更少）,因而非常适合分析那些只能提供微量RNA的样本.     

A convenient and efficient protocol for isolating high-quality RNA from latex of Hevea brasiliensis (para rubber tree)

Isolating high-quality RNA from latex of H. brasiliensis is a prerequisite to elucidating the molecular mechanisms of rubber biosynthesis and its regulation. Here, an improved protocol was developed for latex collection, transportation, storage, and RNA isolation. Compared with existing ones, our protocol eliminated liquid nitrogen for latex collection and subsequent low-temperature (− 70 °C) condition for latex storage, making it more convenient and feasible when latex was collected in remote sampling sites, and latex storage and RNA isolation were conducted in poorly-equipped laboratories. Different methods (UV absorbance scans, denaturing gel electrophoresis, autoradiograph monitoring of cDNA synthesis) were used to confirm the high quality of the RNA prepared with this protocol, whose usefulness was further verified by several practical applications, including construction of one high-quality cDNA library, cloning of the full-length cDNAs of 3 novel Hevea sucrose transporter genes, and semi-quantitative RT-PCR analysis of two rubber-biosynthesis essential genes and one sucrose transporter gene.     

Increased yield of total RNA from fine-needle aspirates for use in expression microarray analysis

Fine-needle aspirate samples hold the potential for gaining valuable insight into the molecular details and prognostic indicators for certain types of cancer in a limited volume of relatively pure tumor cells. Although limited, such clinical samples can be used with high efficiency when analyzed in conjunction with gene-dense expression microarrays. For this reason, it is essential to retrieve as much high-quality genetic material as possible from each fine-needle aspirate sample. We have conducted a study to improve the efficiency of extracting high quality total RNA to use in microarray analysis from single ex vivo fine-needle aspirate samples of 11 breast cancers added to RNAlater RNA Stabilization Reagent immediately upon collection. Approximately half the total RNA from fine-needle aspirate samples of breast cancers was isolated from the supernatant, and that RNA had similar quality and gene expression profile to the RNA that was isolated from the corresponding cell pellet. We recommend that the supernatant not be discarded when extracting RNA from fine-needle aspirate samples stored in RNAlater.     

麦冬根中总RNA的快速提取

目的:从富含多糖、多酚的麦冬根部组织中快速提取总RNA。方法:采用改进的苯酚法,提取液的配制为5%SDS、1mol/LNaAc(pH4.1)、20%HAC、0.1%PVP。结果:采用该方法提取的麦冬总RNA纯度高、完整性好,电泳条带清晰。通过琼脂糖凝胶电泳与紫外吸光度测定产量与纯度,麦冬根部组织总RNA的吸光值D260nm/D280nm值大于1.8,D260nm/D230nm值大于2.0,麦冬块根与不定根RNA的平均产量分别为79.716和76.144μg/g(鲜重)。结论:用本方法提取的RNA可用于后继的抑制消减杂交试验。