Provided are methods and systems for detecting formation of nucleotide-specific ternary complexes comprising a DNA polymerase, a nucleic acid, and a nucleotide complementary to the templated base of the primed template nucleic acid. The methods and systems facilitate determination of the next correct nucleotide without requiring chemical incorporation of the nucleotide into the primer. These results can even be achieved in procedures employing unlabeled, native nucleotides.

Provided are methods and systems for reducing the time needed for sequencing nucleic acids. The approach relies on detecting formation of nucleotide-specific ternary complexes comprising a polymerase (e.g., a DNA polymerizing enzyme), a primed template nucleic acid molecule, and a nucleotide complementary to the templated base of the primed template nucleic acid. The methods and systems facilitate determination of the next correct nucleotide, as well as the subsequent next correct nucleotide from a cycle of examining four different nucleotides without requiring chemical incorporation of any nucleotide into the primer.

Provided are methods and systems for reducing the time needed for sequencing nucleic acids. The approach relies on detecting formation of nucleotide-specific ternary complexes comprising a polymerase (e.g., a DNA polymerizing enzyme), a primed template nucleic acid molecule, and a nucleotide complementary to the templated base of the primed template nucleic acid. The methods and systems facilitate determination of the next correct nucleotide, as well as the subsequent next correct nucleotide from a cycle of examining four different nucleotides without requiring chemical incorporation of any nucleotide into the primer.

The present disclosure provides systems and methods for detecting components of an array of biological, chemical, or physical entities. In an aspect, the present disclosure provides a method for detecting an array of biological, chemical, or physical entities, comprising: (a) using one or more light sensing devices, acquiring pixel information from sites in an array, wherein the sites comprise biological, chemical, or physical entities that produce light; (b) processing the pixel information to identify a set of regions of interest (ROIs) corresponding to the sites in the array that produce the light; (c) classifying the pixel information for the ROIs into a categorical classification from among a plurality of distinct categorical classifications, thereby producing a plurality of pixel classifications; and (d) identifying one or more components of the array of biological, chemical, or physical entities based at least in part on the plurality of pixel classifications.

The present disclosure provides systems and methods for detecting components of an array of biological, chemical, or physical entities. In an aspect, the present disclosure provides a method for detecting an array of biological, chemical, or physical entities, comprising: (a) using one or more light sensing devices, acquiring pixel information from sites in an array, wherein the sites comprise biological, chemical, or physical entities that produce light; (b) processing the pixel information to identify a set of regions of interest (ROIs) corresponding to the sites in the array that produce the light; (c) classifying the pixel information for the ROIs into a categorical classification from among a plurality of distinct categorical classifications, thereby producing a plurality of pixel classifications; and (d) identifying one or more components of the array of biological, chemical, or physical entities based at least in part on the plurality of pixel classifications.

The invention provides compositions comprising nucleic acid complexes for use in monitoring binding interactions and in measuring association and/or dissociation kinetics, detecting analytes including low concentration analytes, and screening library members. In some instances, the nucleic acid complexes are double-stranded nicked nucleic acids comprising a scaffold nucleic acid hybridized to one or more oligonucleotides. In some instances, a first, a second, a third, and optionally a fourth oligonucleotide are linked to moieties that are known to interact with each other or which are suspected of interacting with each other or of interacting with a common moiety such as an analyte. Changes in topology of the complex are used to determine the binding interactions of the various binding partners.

The invention provides compositions comprising nucleic acid complexes for use in monitoring binding interactions and in measuring association and/or dissociation kinetics, detecting analytes including low concentration analytes, and screening library members. In some instances, the nucleic acid complexes are double-stranded nicked nucleic acids comprising a scaffold nucleic acid hybridized to one or more oligonucleotides. In some instances, a first, a second, a third, and optionally a fourth oligonucleotide are linked to moieties that are known to interact with each other or which are suspected of interacting with each other or of interacting with a common moiety such as an analyte. Changes in topology of the complex are used to determine the binding interactions of the various binding partners.

Provided herein, among other things, are various compositions and methods for analyzing chromatin. In some embodiments, the composition may comprise a mixture of a nicking enzyme, four dNTPs, at least one labeled dNTP and, optionally, a polymerase. In some embodiments, this method may comprise: obtaining a sample comprising chromatin, reacting the sample with the composition to selectively label the open chromatin in the sample, and analyzing the labeled sample.

Provided herein, among other things, are various compositions and methods for analyzing chromatin. In some embodiments, the composition may comprise a mixture of a nicking enzyme, four dNTPs, at least one labeled dNTP and, optionally, a polymerase. In some embodiments, this method may comprise: obtaining a sample comprising chromatin, reacting the sample with the composition to selectively label the open chromatin in the sample, and analyzing the labeled sample.

Very simple, highly sensitive detection or quantification of target nucleic acids of interest has been achieved by: hybridizing mask oligonucleotides to regions in a single-stranded region of a nucleic acid to be assayed between which a region to be hybridized by an oligonucleotide probe is positioned, thereby opening the probe-hybridizing region and keeping the single-stranded region of the target nucleic acid stable, and then subjecting this nucleic acid having the single-stranded region to nucleic acid chromatography.