The present disclosure concerns embodiments related to methods of enriching particular DNA for analysis of methylation status and/or profiles, for example in the process of diagnosis of cancer. In particular embodiments, the methods utilize cell-free DNA as a source of DNA instead of genomic DNA and allow for focused enrichment of fragments having two or more enzyme digestion sites and containing at least one CpG site.

Provided herein are compositions and methods for preserving proximity data in nucleic acid samples, by embedding indexing information in the samples prior to fragmentation. Further provided herein are transposon libraries for generating such indexed nucleic acid samples.

A kit for use with a nucleic acid sequencing instrument can include a plurality of combinatorial barcodes sequences meeting the following criteria: each of the combinatorial barcode sequences comprise a plurality of iterations of a sequence motif, where the sequence motif comprises a first nucleotide base from a first group of nucleotide bases followed by a second nucleotide base from a second group of nucleotide bases, the first group and the second group differing from each other; and the plurality of combinatorial barcode sequences is at least 1,000,000 different barcode sequences.

A kit for use with a nucleic acid sequencing instrument can include a plurality of combinatorial barcodes sequences meeting the following criteria: each of the combinatorial barcode sequences comprise a plurality of iterations of a sequence motif, where the sequence motif comprises a first nucleotide base from a first group of nucleotide bases followed by a second nucleotide base from a second group of nucleotide bases, the first group and the second group differing from each other; and the plurality of combinatorial barcode sequences is at least 1,000,000 different barcode sequences.

Electrical detection methods are used to identify and further characterize single-molecule target analytes such as proteins and nucleic acids. A composition including a probe region and a tail region is contacted with a target analyte. The probe region specifically binds to the target analyte. The tail region is coupled to the probe region, and includes a nucleic acid template for polynucleotide synthesis. When conditions are such that polynucleotide synthesis occurs along the tail region, one hydrogen ion is released for every nucleotide that is incorporated into the tail region. A transistor such as an ISFET detects and measures changes in ion concentration, and these measurements can be used to identify the tail region and thus characterize the corresponding target analyte.

Compositions and methods are provided for rapid characterization of Cas endonuclease systems and the elements comprising such systems, including, but not limiting to, rapid characterization of PAM sequences, guide RNA elements and Cas endonucleases. Type II Cas9 endonuclease systems originating from Brevibacillus laterosporus, Lactobacillus reuteri Mlc3, Lactobacillus rossiae DSM 15814, Pediococcus pentosaceus SL4, Lactobacillus nodensis JCM 14932, Sulfurospirillum sp. SCADC, Bifidobacterium thermophilum DSM 20210, Loktanella vestfoldensis, Sphingomonas sanxanigenens NX02, Epilithonimonas tenax DSM 16811, Sporocytophaga myxococcoides are described herein. The present disclosure also describes methods for genome modification of a target sequence in the genome of a cell, for gene editing, and for inserting a polynucleotide of interest into the genome of a cell.

The invention is directed to methods for synthesizing oligonucleotides direction on biomolecules or cells living or fixed. In some embodiments, template-free enzymatic synthesis is implemented under biological conditions with successive cycles of (i) enzymatic addition of a 3′-O-blocked nucleoside triphosphate and (ii) enzymatic deblocking of the incorporated nucleotide to regenerate a free 3′ hydroxyl. The invention has applications in single-cell cDNA library construction and analysis.

Provided are methods and systems useful for screening large libraries of effector molecules. Such methods and systems are particularly useful in microfluidic systems and devices. The methods and systems provided herein utilize encoded effectors to screen large libraries of effectors.

Provided are methods and systems useful for screening large libraries of effector molecules. Such methods and systems are particularly useful in microfluidic systems and devices. The methods and systems provided herein utilize encoded effectors to screen large libraries of effectors.

Disclosed herein are methods for tracking solutions, (e.g., reaction conditions in solutions). In some embodiments, the method comprises: contacting a first lanthanide-chelator complex to a first solution to generate a first barcoded solution, wherein the first lanthanide-chelator complex comprises a first lanthanide chelated by a first chelator; contacting a second lanthanide-chelator complex to a second solution to generate a second barcoded solution, wherein the second lanthanide-chelator complex comprises a second lanthanide chelated by a second chelator; mixing the first barcoded solution and the second barcoded solution to form one or more mixtures; and identifying the first lanthanide ions in the mass spectrum and the second lanthanide ions in the mass spectrum to track the condition of each of the one or more mixtures.