Improvements in sample preparation for ChIP-chip assays
Ontology highlight
ABSTRACT: We have improved the new protocol for ChIP-chip by using pooling method. The new method has produced reproducible binding patterns and low background signals. Keywords: ChIP-chip
Project description:We have improved the new protocol for ChIP-chip by using pooling method. The new method has produced reproducible binding patterns and low background signals. We have performed and compared three methods for ChIP-chip samples: LMPCR, 10 Pooled Samples and WGA.
Project description:A single chromatin immunoprecipitation (ChIP) sample does not provide enough DNA for hybridization to a genomic tiling array. A commonly used technique for amplifying the DNA obtained from ChIP assays is ligation-mediated PCR (LM-PCR). However; using this amplification method, we could not identify Oct4 binding sites on genomic tiling arrays representing 1% of the human genome (ENCODE arrays). In contrast, hybridization of a pool of 10 ChIP samples to the arrays produced reproducible binding patterns and low background signals. However the pooling method would greatly increase the number of ChIP reactions needed to analyze the entire human genome. Therefore, we have adapted the GenomePlex whole genome amplification (WGA) method for use in ChIP-chip assays; detailed ChIP and amplification protocols used for these analyses are provided as supplementary material. When applied to ENCODE arrays, the products prepared using this new method resulted in an Oct4 binding pattern similar to that from the pooled Oct4 ChIP samples. Importantly, the signal-to-noise ratio using the GenomePlex WGA method is superior to the LM-PCR amplification method.
Project description:Development and evaluation of nested nanowell (N2) chip in single-cell proteomics. The newly designed chip helps to improve the sensitivity and robustness of the tandem mass tag labeling approach by sizing down wells.
Project description:Single-cell RNA-Sequencing has led to many novel discoveries such as the detection of rare cell populations, microbial populations, and cancer mutations. The quality of single-cell transcriptomics relies heavily on sample preparation and cell sorting techniques that best preserve RNA quality while removing dead cells or debris prior to cDNA generation and library preparation. Magnetic bead cell enrichment is a simple process of cleaning up a sample but can only separate on a single-criterion. Droplet-based cell sorters, on the other hand, allows for higher purity of sorted cells gated on several fluorescent and scatter properties. The downside of traditional droplet-based sorters is their operational complexity, accessibility, and potential stress on cells due to their high-pressure pumps. The WOLF® Cell Sorter, and WOLF G2®, developed by NanoCellect Biomedical, are novel microfluidic-based cell sorters that use gentle sorting technology compatible with several RNA-sequencing platforms. The experiments highlighted here demonstrate how microfluidic sorting can be successfully used to remove debris and unwanted cells prior to genomic sample preparation resulting in more data per cell and improved library complexity.
Project description:In this work, we propose a new high-throughput ultrafast method for large scale proteomics approaches by speeding the classic filter aided sample preparation protocol, FASP. The new US-FASP method matches the analytical minimalism roles as time, cost, sample requirement, reagent consumption, energy requirements and production of waste products are reduced to a minimum while maintaining high sample throughput in a robust manner as all the advantages of the filter aided sample preparation protocol are maintained.
Project description:Chromatin immunoprecipitation followed by deep sequencing (ChIP-seq) and its ultra-high resolution cousin ChIP-exo are methods that identify where proteins bind along any genome in vivo. ChIP-exo achieves near-base pair resolution by creating exonuclease stop sites just 5’ to where formaldehyde-induced protein-DNA cross-links occur. Whereas construction of ChIP genomic libraries is straightforward and widely adopted for ChIP-seq, ChIP-exo is technically more involved which has resulted in limited adoption. Here we describe multiple ChIP-exo protocols, each with use-specific advantages and limitations. The new versions are greatly simplified through removal of multiple enzymatic steps. This is achieved in part through the use of Tn5 tagmentation and/or single-stranded DNA ligation. The result is greater library yields, lower processing time, and lower cost. A similar streamlined approach was developed for ChIP-seq, called ChIP-seq 1-step, where library construction is achieved in one-step.
Project description:Microfluidic devices coupled to MS promises low manufacturing costs, low sample consumption and channels with a high surface area to volume ratio and tailorable functional groups. Here, we describe a thiol-ene-based microfluidic chip that is capable of sample loading, desalting and on-chip reversed phase chromatography prior to on-chip electrospray ionization for the intact analysis of proteins and peptides, as well as, for on-chip bottom-up proteomics workflows coupled directly with mass spectrometry.
Project description:Chromatin immunoprecipitation followed by deep sequencing (ChIP-seq) and its ultra-high resolution cousin ChIP-exo are methods that identify where proteins bind along any genome in vivo. ChIP-exo achieves near-base pair resolution by creating exonuclease stop sites just 5’ to where formaldehyde-induced protein-DNA cross-links occur. Whereas construction of ChIP genomic libraries is straightforward and widely adopted for ChIP-seq, ChIP-exo is technically more involved which has resulted in limited adoption. Here we describe multiple ChIP-exo protocols, each with use-specific advantages and limitations. The new versions are greatly simplified through removal of multiple enzymatic steps. This is achieved in part through the use of Tn5 tagmentation and/or single-stranded DNA ligation. The result is greater library yields, lower processing time, and lower cost. A similar streamlined approach was developed for ChIP-seq, called ChIP-seq 1-step, where library construction is achieved in one-step.
Project description:DNA replication occurs in a defined temporal order known as the replication-timing (RT) program. RT is regulated during development in discrete chromosomal units, coordinated with transcriptional activity and 3D genome organization. Here, we developed a sample preparation method to measure RT genome-wide that does not require fixation.