Project description:Background: During the analysis of ripening related gene expression in tomato fruit, we observed a bias towards certain classes of messenger RNA based upon the type of buffer used in the initial step of the extraction procedure. We postulated that there was a functional association of the separated transcripts. To test this hypothesis, we carried out extractions from the same tissue sample where only the buffer varied. Transcripts were hybridised to Affymetrix oligo arrays and the data was analysed according to the predicted cellular component of the encoded proteins. Results: The use of an extraction buffer that lacked high levels of caeotropic agents resulted in a reduction of mRNAs encoding proteins that were either secreted or were predicted to be routed through the endomembrane system and hence could have been bound to the endoplasmic reticulum in polyribosomes. Extraction of the cell debris immediately following the initial buffer based extraction and subsequent micro array analysis revealed that the expected transcripts could be recovered. This demonstrated that the buffer was separating the mRNAs based on the cellular component of the encoded proteins. Analysis of selected transcripts by northern hybridisation again supported this theory. Conclusions: Some traditional buffers used for fruit RNA extraction selectively deplete for transcripts encoding proteins that are membrane-associated or secreted. This can be explained if polyribosomes that are bound to the endoplasmic reticulum (ER) are not effectively disrupted when the extraction buffer lacks either detergent or organic solvents. These findings have important implications with respect to experimental bias, as well as opportunities for message enrichment and protein characterisation. GeneChip analyses were performed to analyse the effect of using different extraction protocols on Solanum lycopersicum pericarp.
Project description:Background: During the analysis of ripening related gene expression in tomato fruit, we observed a bias towards certain classes of messenger RNA based upon the type of buffer used in the initial step of the extraction procedure. We postulated that there was a functional association of the separated transcripts. To test this hypothesis, we carried out extractions from the same tissue sample where only the buffer varied. Transcripts were hybridised to Affymetrix oligo arrays and the data was analysed according to the predicted cellular component of the encoded proteins. Results: The use of an extraction buffer that lacked high levels of caeotropic agents resulted in a reduction of mRNAs encoding proteins that were either secreted or were predicted to be routed through the endomembrane system and hence could have been bound to the endoplasmic reticulum in polyribosomes. Extraction of the cell debris immediately following the initial buffer based extraction and subsequent micro array analysis revealed that the expected transcripts could be recovered. This demonstrated that the buffer was separating the mRNAs based on the cellular component of the encoded proteins. Analysis of selected transcripts by northern hybridisation again supported this theory. Conclusions: Some traditional buffers used for fruit RNA extraction selectively deplete for transcripts encoding proteins that are membrane-associated or secreted. This can be explained if polyribosomes that are bound to the endoplasmic reticulum (ER) are not effectively disrupted when the extraction buffer lacks either detergent or organic solvents. These findings have important implications with respect to experimental bias, as well as opportunities for message enrichment and protein characterisation.
Project description:ADP-ribosylation is a posttranslational modification whose HCD products are dominated by complete or partial modification losses, complicating peptide sequencing and acceptor site localization efforts. We tested whether in-source CID performed on a quadrupole Orbitrap could convert ADPr to the smaller phosphoribose-H2O derivative to facilitate HCD-dependent peptide sequencing. Human macrophage like cell line THP-1-derived ADP-ribosyl (ADPr) peptides were analyzed on a quadrupole Orbitrap. We monitored the interconversion of ADPr (+541.061 Da) to phosphoribosyl-H2O (+193.997 Da) peptides while varying the source and high-field asymmetric waveform ion mobility mass spectrometry (FAIMS) compensation voltages. Xcorr and ptmRS were used to evaluate peptide sequencing and acceptor site confidence, respectively. In-source CID-HCD-derived phosphoribosyl-H2O acceptor sites were compared to those determined by EThcD, performed on a quadrupole ion trap Orbitrap. Interconversion of ADPr peptides to their phosphoribosyl-H2O derivatives increased with increasing source voltage (up to 50V), as judged by monitoring the corresponding modification loss ([adenosine monophosphate/AMP]+) and the number of identified phosphoribosyl-H2O peptide identifications. The average Xcorr increased from 1.36 (ADPr) to 2.26 (phosphoribosyl-H2O), similar to that achieved with EThcD for ADPr peptides (2.29). The number of high-confidence acceptor sites (>95%) also increased, from 31% (ADPr) to 70% (phosphoribosyl-H2O), which was comparable to EThcD (70%). In-source CID converts ADP-ribosyl to phosphoribosyl-H2O peptides that are more amenable to HCD-dependent peptide sequencing, providing an alternative method for acceptor site determination when ETD-based methods are not available.
Project description:Purpose: Description of a spike-adjusting-method (SAM) to normalize ChIP-seq data . Methods: We performed ChIP-seq of POLR3D and POLR2B with mouse liver supplemented with 2.5% of human DNA. Human DNA will be used as an internal control for ChIP-seq quantification. Results: We show that using the SAM for ChIP-seq quantification improve similarity of POLR3D and POLR2B ChIP-seq replicates samples and improve difference between samples originate from different conditions. Conclusions: The SAM improves comparison of ChIP-seq samples, either by increasing similarity between replicates or by emphasise differences between conditions. Chromatin Immuno-precipitations were performed with antibodies directed against POLR3D (Pol III) and POLR2B (Pol II) using mouse liver material supplemented with human DNA. Immuno-precipitated DNA was next sequenced using Illumina HiSeq. Three different concentrations of human spiked DNA were tested for the Pol III ChIP (2.5%, 5% and 10%). We also sequenced the corresponding inputs (crosslinked DNA from mouse liver). Two concentrations of human spiked DNA (5% and 10%) were tested for the Pol 2 ChIP. We also sequenced the corresponding inputs (crosslinked DNA from mouse liver).
Project description:There is growing scientific and regulatory interest in transcriptomic points of departure (tPOD) values from high-throughput in vitro experiments. To further help democratize tPOD research, here we outline ‘tPOD-seq’ which links microplate-based exposure methods involving cell lines for human (Caco-2, Hep G2) and environmental (rainbow trout RTgill-W1) health, with a commercially available RNA-seq kit, with a cloud-based bioinformatics tool (ExpressAnalyst.ca). To demonstrate tPOD-seq’s utility, we applied it to derive tPODs for solvents (dimethyl sulfoxide, DMSO; methanol) and positive controls (3,4-dichloroaniline, DCA; hydrogen peroxide, H2O2) commonly used in toxicity testing. The majority of reads mapped to protein coding genes (~10.5k for fish cells; ~7k for human cells), and about 50% of differentially expressed genes were curve-fitted from which 90% yielded gene benchmark doses. The most robust transcriptomic responses were caused by DMSO exposure, and tPOD values were 31-136.6 mM across the cell lines. OECD test guideline 249 (RTgill-W1 cells) recommends the use of DCA and here we calculated a tPOD of ~0.005 to ~0.076 mMmg/L. Finally, exposure of the two human cell lines to H2O2 resulted in similar tPOD values that ranged from 0.68-1.1 in Caco-2 cells and 0.0048-0.03 in Hep G2 cells. The methods outlined here are designed to be performed in laboratories with basic molecular and cell culture facilities, and the performance and scalability of the tPOD-seq approach can be determined with additional case studies.
Project description:Compared to using dispersive SPE (dSPE) based on the QuEChERS procedure, we found similar reproducibility using high purity MgSO4 to analyze standard reference material (SRM) of human serum and human plasma samples and slightly higher recovery of targeted chemicals using MgSO4. To avoid contamination by environmental chemicals in solvents and reagents used for QuEChERS, we chose to use high purity MgSO4 to remove water-soluble interferences.
Project description:Soil is an inherently complex matrix and as such, we believe when performing culture-independent microbial community analyses using the 'omics' suite of tools, all biomolecules investigated should be co-extracted from the same biological sample. To this end, we developed a robust, cost-effective DNA, RNA and protein co-extraction method for soil. The samples deposited here represent 3 biological replicates from one of eight soil types tested in this work.
Project description:Induced phase separation extraction (IPSE) is an efficient sample clean-up technique that can replace liquid-liquid extraction (LLE). The purpose of this study was to miniaturize IPSE by carrying it out in a microfluidic chip. An IPSE chip was designed and evaluated for its ability to separate and purify samples on a microscale. The 5 × 2 cm chip was fed with a solution of polar to non-polar model compounds in acetonitrile-water (1:1). In the 100 µm wide and 40 µm deep microchannels, the sample solution was efficiently separated into two immiscible phases by adding a hydrophobic solvent as inducer. Analytes present in the sample solution each migrated to their own favorable phase upon phase separation. After optimization, extraction and fractionation were easily and efficiently achieved. The behavior of analytes with a pH-dependent partitioning could be influenced by adjusting the pH of the sample solution. Scutellaria baicalensis extract, used in Traditional Chinese Medicine (TCM), was successfully separated in aglycones and glycosides. In this microscale system, the sample and solvent consumption is reduced to microliters, while the time needed for the sample pretreatment is less than one minute. Additionally, the extraction efficiency can reach up to 98.8%, and emulsion formation is avoided.
Project description:The aim of this study is to determine if, using antioxidant drugs, it is possible to interfere with the proliferative capabilities of the human glioblastoma (GBM) tumor-initiating cells (TICs). To establish which cellular processes are activated in GBM TICs by the antioxidants NAC, Tiron and Trolox, we generated and analyzed the gene expression profiles after treatment with these compounds and with H2O and EtOH (vehicles).