Project description:<p>Untargeted features from the Bermuda Atlantic Time-series Study (BATS) site collected during the time period spanning 2016 to 2019. Metabolites were sampled from surface seawater to 1000 m deep and throughout the year. Dissolved organic matter extracts were analyzed in positive and negative ion mode with an ultra-high performance liquid chromatography system (Vanquish UHPLC, Thermo Scientific) coupled with an Orbitrap Fusion Lumos Tribid mass spectrometer.</p>
Project description:Despite the overwhelming information about sRNAs, one of the biggest challenges in the sRNA field is characterizing sRNA targetomes. Thus, we develop a novel method to identify RNAs that interact with a specific sRNA, regardless of the type of regulation (positive or negative) or targets (mRNA, tRNA, sRNA). This method is called MAPS: MS2 affinity purification coupled with RNA sequencing. As proof of principle, we identified RNAs bound to RybB, a well-characterized E. coli sRNA. Identification of RNAs co-purified with MS2-RybB in a rne131 ΔrybB strain. RybB (without MS2) was used as control
Project description:Despite the overwhelming information about sRNAs, one of the biggest challenges in the sRNA field is characterizing sRNA targetomes. Thus, we develop a novel method to identify RNAs that interact with a specific sRNA, regardless of the type of regulation (positive or negative) or targets (mRNA, tRNA, sRNA). This method is called MAPS: MS2 affinity purification coupled with RNA sequencing. As proof of principle, we identified RNAs bound to RyhB, a well-characterized E. coli sRNA. Identification of RNAs co-purified with MS2-RyhB in a rne131 ?ryhB strain. RyhB (without MS2) was used as control
Project description:Genome-wide gene expression in 33 fusion-positive and 25 fusion-negative rhabdomyosarcoma cases was studied using GeneChip Human Genome U133 Plus2 (Affymetrix) Fusion-positive versus fusion-negative rhabdomyosarcoma tumors
Project description:Protein abundance profiling using isobaric labeling is a well-established quantitative mass spectrometry technique. However, ratio distortion resulting from co-isolated and co-fragmented ions - commonly referred to as interference - remains a caveat of this technique. Tribrid mass spectrometers, such as the Orbitrap Fusion and the Orbitrap Fusion Lumos with a triple mass analyzer configuration, facilitate methods (namely SPS-MS3) that can help alleviate interference. Yet, few standards are available to measure interference. Here we introduce the TKO6 standard that assesses ion interference and is designed specifically for data acquired at low (unit) mass resolution. We use TKO6 to compare the degree of interference in MS2 versus MS3-based quantitation methods, data acquisition methods of different lengths, and ion trap-based TMT reporter ion analysis (IT-MS3). We show that the TKO6 standard is a valuable tool for assessing data quality and is particularly useful for benchmarking ion trap-based SPS-MS3 analyses.
Project description:Nearly every step of RNA regulation is mediated by binding proteins (RBPs). The most common method to identify specific RBP target transcripts in vivo is by crosslinking (“CLIP” and its variants), which rely on protein-RNA crosslinking and specific antibodies. Another recently introduced method exploits RNA editing, with the hyperactive mutant catalytic domain of ADAR covalently attached to a specific RBP (“HyperTRIBE”). Both CLIP and TRIBE approaches suffer from difficulties in distinguishing real RNA targets from false negative and especially false positive signals. To critically evaluate this problem, we used fibroblasts from a mouse where every endogenous β-actin mRNA molecule was tagged with the bacteriophage MS2 RNA stem loops in the β-actin 3’ UTR; hence there is only a single bona fide target mRNA for the MS2 capsid protein (MCP). CLIP and HyperTRIBE (hereafter referred to as TRIBE) could both detect the single RNA target, albeit with some false positives (transcripts lacking the MS2 stem loops). Consistent false positive CLIP signals could be attributed to nonspecific antibody interactions. However, to our surprise the putative false positive TRIBE targets correlated with the location of genes spatially proximal to the β-actin gene. This result indicates that MCP-ADAR bound to β-actin mRNA contacted and edited nearby nascent transcripts, as evidenced by frequent intronic editing. Importantly, nascent transcripts on nearby chromosomes were also edited, agreeing with the interchromosomal contacts observed in chromosome paint and Hi-C. These results were repeated in human osteosarcoma cells with a randomly integrated and inducible MS2 reporter and indicated that MS2-TRIBE can be applied to a broad array of cells and transcripts. The identification of nascent RNA-RNA contacts imply that RNA-regulatory proteins such as splicing factors can associate with multiple nascent transcripts and thereby form domains of post-transcriptional activity, which increase their local concentrations. These results indicate that TRIBE combined with the MS2 system, MS2-TRIBE, is a new tool to study nuclear RNA organization and regulation.