Project description:We have developed a total RNA amplification and labeling strategy for use with Affymetrix GeneChips. Our protocol, which we denote BIIB, employs two rounds of linear T7 amplification followed by Klenow labeling to generate a biotinylated cDNA. In benchmarking studies using a titration of mouse universal total RNA, BIIB outperformed commercially available kits in terms of sensitivity, accuracy, and amplified target length, while providing equivalent results for technical reproducibility. BIIB maintained 50 and 44% present calls from 100 and 50 pg of total RNA, respectively. Inter- and intrasample precision studies indicated that BIIB produces an unbiased and complete expression profile within a range of 5 ng to 50 pg of starting total RNA. From a panel of spiked exogenous transcripts, we established the BIIB linear detection limit to be 20 absolute copies. Additionally, we demonstrate that BIIB is sensitive enough to detect the stochastic events inherent in a highly diluted sample. Using RNA isolated from whole tissues, we further validated BIIB accuracy and precision by comparison of 224 expression ratios generated by quantitative real-time PCR. The utility of our method is ultimately illustrated by the detection of biologically expected trends in a T cell/B cell titration of 100 primary cells flow sorted from a healthy mouse spleen. Keywords: Development and validation of an amplification and labeling protocol for transcriptional profiling on Affymetrix GeneChips, cDNA target on Affymetrix Genechip, small or limiting total RNA samples
Project description:We have developed a total RNA amplification and labeling strategy for use with Affymetrix GeneChips. Our protocol, which we denote BIIB, employs two rounds of linear T7 amplification followed by Klenow labeling to generate a biotinylated cDNA. In benchmarking studies using a titration of mouse universal total RNA, BIIB outperformed commercially available kits in terms of sensitivity, accuracy, and amplified target length, while providing equivalent results for technical reproducibility. BIIB maintained 50 and 44% present calls from 100 and 50 pg of total RNA, respectively. Inter- and intrasample precision studies indicated that BIIB produces an unbiased and complete expression profile within a range of 5 ng to 50 pg of starting total RNA. From a panel of spiked exogenous transcripts, we established the BIIB linear detection limit to be 20 absolute copies. Additionally, we demonstrate that BIIB is sensitive enough to detect the stochastic events inherent in a highly diluted sample. Using RNA isolated from whole tissues, we further validated BIIB accuracy and precision by comparison of 224 expression ratios generated by quantitative real-time PCR. The utility of our method is ultimately illustrated by the detection of biologically expected trends in a T cell/B cell titration of 100 primary cells flow sorted from a healthy mouse spleen. Experiment Overall Design: Various experimental designs were used as part of the validation process for this total RNA amplification and labeling protocol. 103 samples were analyzed on Affymetrix GeneChips as part of this GEO series. Details of the BIIB protocol and supporting experiments are published in Genomics. 2006 Jul;88(1):111-21
Project description:For more than a decade, microarrays have been a powerful and widely used tool to explore the transcriptome of biological systems. However, the amount of biological material from cell sorting or laser capture microdissection is much too small to perform microarray studies. To address this issue, RNA amplification methods have been developed to generate sufficient targets from picogram amounts of total RNA to perform microarray hybridisation. In this study, four commercial protocols for amplification of picograms amounts of input RNA for microarray expression profiling were evaluated and compared. The quantitative and qualitative performances of the methods were assessed. Microarrays were hybridised with the amplified targets and the amplification protocols were compared with respect to the quality of expression profiles, reproducibility within a concentration range of input RNA, and sensitivity. Four commercial protocols for amplification of picograms amounts of input RNA for microarray expression profiling were evaluated and compared. For each protocol, one RNA amplification was performed from 250 pg, and one from 500 pg of human universal RNA by two operators in two independent laboratories and compared to the amplified aRNA obtained from 2 µg and 100 ng RNA inputs following the standard protocol proposed by Affymetrix. A negative control (amplification without total RNA) and a positive control (if available) were included in each experimental batch. Samples indicating 50, 100, and 1000 pg RNA inputs correspond to 3 additional quantities of total RNA used to synthesise the cDNA target using the nugen protocol for comparison (250, 500 pg + 50, 100, 1000 pg).
Project description:We have performed analyses of murine primary bone marrow derived neutrophils challenged with either ultra-low dose or high dose of LPS. Neutrophils can be differentially programmed to distinct states by varying dosages of LPS. Purified bone marrow neutrophils were treated with PBS, 100 pg/ml LPS or 100 ng/ml LPS overnight, and harvested for scRNAseq analysis to examine their profiles of gene expression.
Project description:We conducted a large-scale control experiment to assess the transfer function of three scRNA-seq methods and factors modulating the function. Our approach was to dilute bulk total RNA (from a single source) to levels bracketing single-cell levels of total RNA (10 pg and 100 pg) in replicates and amplifying the RNA to levels sufficient for RNA sequencing.
Project description:<p>The sample to be tested was fully ground into powder in the grinder, 50 mg of the sample was freeze-dried, 1000 μL of the extraction solution containing the inner target was added (methanol:acetonitrile:water, 2:2:1, v/v/v, internal standard concentration 20 mg/L) and vortex mixed for 30 s; then add the steel ball to the 45 Hz grinder for 10 min, ultrasonic 10 min; the sample to be tested is obtained after filtration. When detecting metabolites, metabolite determination was performed based on the LC-MS system, which mainly consists of Waters Acquity I-Class PLUS ultra-high performance liquid tandem and Waters Xevo G2-XS QTof high-resolution mass spectrometer. Meanwhile, the Waters Acquity UPLC HSS T3 column (1.8 um 2.1 x 100 mm) was used as the chromatographic column. Positive and negative ion modes were used to determine the metabolites. Mobile phase A: 0.1% formic acid aqueous solution; Mobile phase B: 0.1% acetonitrile formate. The mobile phase conditions of liquid chromatography were as follows: the flow rate was 400 μL/min, 0.0 min: 98% flow A, 2% flow B; 0.25 min: 98% flow A, 2% flow B, 10.0 min: 2% flow A, 98% flow B; 13.0 min: 2% flow A, 98% flow B; 13.1 min: 98% flow A, 2% flow B; 15.0 min: 98% flow A, 2% flow B. MSe mode controlled by acquisition software (MassLynx v4.2, Waters) was used for primary and secondary mass spectrum data acquisition. ESI ion source parameters are as follows: Capillary voltage, 2500 V (positive ion mode) or -2000 V (negative ion mode); Cone hole voltage, 30 V; Ion source temperature, 100 °C; Desolvent temperature, 500 °C; Air flow rate, 50 L/h; Desolvent gas flow rate, 800 L/h; Plastic-nucleus ratio (m/z) collection range 50-1200 m/z. In the qualitative and quantitative analysis of metabolites, the original data collected by MassLynx v4.2 were processed by the Progenesis QI software for peak extraction, peak alignment, and other data, and the metabolites were identified based on the Progenesis QI software online METLIN database. Then, based on the results of the total score, MS2 score, and mass error (ppm), the metabolites were qualitatively determined.</p>
Project description:ChIP-seq is used to map transcription factor occupancy and generate epigenetic profiles genome-wide. The requirement of nano-scale ChIP DNA for generation of sequencing libraries has impeded ChIP-seq on in vivo tissues of low cell numbers. We describe a robust, simple and scalable methodology for ChIP-seq of low-abundant cell populations, reliably amplifying 50 pg of ChIP DNA, corresponding to ~30,000 input cells for transcription factor ChIP (CEBPA) and 3,000 cells for histone mark ChIP (H3K27me3). This represents a significant advance compared to existing technologies, which involve complex and time-consuming steps of pre-amplification, making them susceptible to experimental biases. ChIP-seq of histone modifications H3K27me3 (2 biological replicates (I+II) , 2 ng input), H3K4me3 (2 biological replicates (II+III), 2 ng input), transcription factor CEBPA (2 biological replicates (I+II), 300 pg input), 4 diluted CEBPA libraries (pool of ChIP from 3 biol. replicates (I+II+III) 3x 100 pg input, 1x 50 pg). Additonal ChIP-seq using 10,000 cells, 1 biological replicate of each H3K4me3 and CEBPA.
Project description:We have generated immune-enhancing neutrophils by culturing murine primary bone marrow derived neutrophils with either super-low dose of LPS. Immune-enhancing neutrophils preferentially express co-stimulatory molecules such as CD74, CD44 and CD86, and exhibit reduced expression of CD11b. Purified bone marrow neutrophils were treated with PBS or 100 pg/ml LPS overnight in the presence of GM-CSF, and harvested for scRNAseq analysis to examine their profiles of gene expression.
Project description:A systems-level understanding of a small but essential population of cells in development or adulthood (e.g., somatic stem cells) requires accurate quantitative monitoring of genome-wide gene expression, ideally from single cells. We report here a strategy to globally amplify mRNAs from single cells for highly quantitative high-density oligonucleotide microarray analysis that combines a small number of directional PCR cycles with subsequent linear amplification. Using this strategy, both the representation of gene expression profiles and reproducibility between individual experiments are unambiguously improved from the original method, along with high coverage and accuracy. Experiment Overall Design: To verify the ability of the developed method, we prepared total RNA from ES cells and diluted it to the single-cell level (10 pg). Eight array data from the cDNA samples amplified independently from the 10 pg RNA (amplified samples) were compared to each other, and to eight array data from the undiluted 5 ug RNA (nonamplified controls). Since all the materials were the same, all of the observed variations were attributable to the methodogoly.
Project description:ATMs, which can constitute up to 50% of the cells in adipose tissue of obese mice 5, play a pivotal role in both metabolic and immune regulation of adipose tissue. This is particularly evident in both healthy states and in conditions associated with metabolic syndrome. To delve into the precise mechanisms of the ATMs in response to exercise, we utilized exercise-induced primary ATMs and miRNAs microarray to investigate the effects of an 8-week aerobic exercise training on ATMs. Following the exercise regimen, ATMs were sorted using flow cytometer and subsequently analyzed through bioinformatics analysis to identify changes in miRNA expression.