Abstract: Methods, compositions, and systems are provided for characterization of modified nucleic acids. In certain preferred embodiments, single molecule sequencing methods are provided for identification of modified nucleotides within nucleic acid sequences. Modifications detectable by the methods provided herein include chemically modified bases, enzymatically modified bases, abasic sites, non-natural bases, secondary structures, and agents bound to a template nucleic acid.

Abstract: Compositions, methods and systems are provided for the isolation of polymerase-nucleic acid complexes. Complexes can be separated from free enzyme by using hook molecules to target single stranded regions on the nucleic acid. Active complexes can be isolated from mixtures having both active and inactive complexes by initiating nucleic acid synthesis so as to open up a portion of a double stranded region rendering that region single stranded. Hook molecules are targeted to bind the sequences that are thus exposed. The hook molecules bound to active polymerase-nucleic acid complex are isolated, and the active polymerase-nucleic acid complexes released.

Abstract: Provided are methods and compositions for the production of linear single-stranded nucleic acids, which can be used as templates in high-throughput sequencing systems. Also provided are methods and compositions for the production of closed single-stranded nucleic acid loops, which can be used as templates in high-throughput sequencing systems.

Abstract: Compositions and methods for nucleic acid sequencing include template constructs that comprise double stranded portions in a partially or completely contiguous constructs, to provide for redundant sequence determination through one or both of sequencing sense and antisense strands, and iteratively sequencing the entire construct multiple times. Additional sequence components are also optionally included within such template constructs. Methods are also provided for the use and preparation of these constructs as well as sequencing compositions for their application.

Abstract: Methods, substrates, and systems for diagnostic sequencing are provided. Small circles of nucleic acids from about 10 bases to about 200 bases can be sequenced, for example using template dependent sequencing by synthesis. The use of small circles of nucleic acids allows for repeated sequencing of the same portions of the nucleic acid, providing for higher accuracy sequence determinations.

Abstract: Provided are methods and compositions for the production of linear single-stranded nucleic acids, which can be used as templates in high-throughput sequencing systems. Also provided are methods and compositions for the production of closed single-stranded nucleic acid loops, which can be used as templates in high-throughput sequencing systems.

Abstract: Provided are methods for sequencing a nucleic acid with a sequencing enzyme, e.g., a polymerase or exonuclease. The sequencing enzyme can optionally be exchanged with a second sequencing enzyme, which continues the sequencing of the nucleic acid. In certain embodiments, a template is fixed to a surface through a template localizing moiety. The template localizing moiety can optionally anneal with the nucleic acid and/or associate with the sequencing enzyme. Also provided are compositions comprising a nucleic acid and a first sequencing enzyme, which can sequence the nucleic acid and optionally exchange with a second sequencing enzyme present in the composition. Compositions in which a template localizing moiety is immobilized on a surface are provided. Also provided are methods for using data from analytical reactions wherein two different enzymes are employed, e.g., at a same or different reaction regions.

Abstract: Compositions and methods for nucleic acid sequencing include template constructs that comprise double stranded portions in a partially or completely contiguous constructs, to provide for redundant sequence determination through one or both of sequencing sense and antisense strands, and iteratively sequencing the entire construct multiple times. Additional sequence components are also optionally included within such template constructs. Methods are also provided for the use and preparation of these constructs as well as sequencing compositions for their application.

Abstract: Methods, devices, and systems for performing intermittent detection during analytical reactions are provided. Such methods facilitate collection of reaction data from disparate reaction times. Further, such methods are useful for reducing photo-induced damage of one or more reactants in an illuminated analytical reaction at a given reaction time. In preferred embodiments, the reaction mixture is subjected to at least one illuminated and non-illuminated period and allowed to proceed such that the time in which the reaction mixture is illuminated is less than a photo-induced damage threshold period.

Abstract: Methods of separating tagged nucleic acid fragments from populations of fragments are provided. The fragments are produced from a population of tagged nucleic acids. In some cases, the population of tagged nucleic acids comprises a population of clonal nucleic acids.

Abstract: Methods, substrates, and systems for diagnostic sequencing are provided. Small circles of nucleic acids from about 10 bases to about 200 bases can be sequenced, for example using template dependent sequencing by synthesis. The use of small circles of nucleic acids allows for repeated sequencing of the same portions of the nucleic acid, providing for higher accuracy sequence determinations.

Abstract: Provided are methods of producing low copy number circularized nucleic acid variants that can be distributed to reaction volumes. The methods include providing a template nucleic acid; producing a population of clonal nucleic acids from the template nucleic acid; generating a set of partially overlapping nucleic acid fragments from the population of clonal nucleic acids; circularizing the partially overlapping nucleic acid fragments to produce circularized nucleic acid variants; and aliquotting the circularized nucleic acid variants into reaction volumes. Related compositions of nucleic acid templates are also provided.

Abstract: Methods, compositions, and systems are provided for characterization of modified nucleic acids. In certain preferred embodiments, single molecule sequencing methods are provided for identification of modified nucleotides within nucleic acid sequences. Modifications detectable by the methods provided herein include chemically modified bases, enzymatically modified bases, abasic sites, non-natural bases, secondary structures, and agents bound to a template nucleic acid.

Abstract: Methods, compositions, and systems are provided for characterization of modified nucleic acids. In certain preferred embodiments, single molecule sequencing methods are provided for identification of modified nucleotides within nucleic acid sequences. Modifications detectable by the methods provided herein include chemically modified bases, enzymatically modified bases, abasic sites, non-natural bases, secondary structures, and agents bound to a template nucleic acid.

Abstract: Provided are methods for sequencing a nucleic acid that include fixing a template to a surface through a template localizing moiety and sequencing the nucleic acid with a sequencing enzyme, e.g. a polymerase or exonuclease. The sequencing enzyme can optionally be exchanged with a second sequencing enzyme, which continues the sequencing of the nucleic acid. The template localizing moiety can optionally anneal with the nucleic acid and/or associate with the sequencing enzyme. Also provided are compositions comprising a nucleic acid fixed to a surface via a template localizing moiety, and a first sequencing enzyme, which can sequence the nucleic acid and optionally exchange with a second sequencing enzyme present in the composition. Compositions in which a template localizing moiety is immobilized on a surface are provided. Compositions for sequencing reactions are provided. Also provided are sequencing systems comprising reaction regions in which or near which template localizing moieties are immobilized.

Abstract: Methods, devices, and systems for performing intermittent detection during analytical reactions are provided. Such methods facilitate collection of reaction data from disparate reaction times. Further, such methods are useful for reducing photo-induced damage of one or more reactants in an illuminated analytical reaction at a given reaction time. In preferred embodiments, the reaction mixture is subjected to at least one illuminated and non-illuminated period and allowed to proceed such that the time in which the reaction mixture is illuminated is less than a photo-induced damage threshold period.

Abstract: Methods, devices, and systems for performing intermittent detection during analytical reactions are provided. Such methods facilitate collection of reaction data from disparate reaction times. Further, such methods are useful for reducing photo-induced damage of one or more reactants in an illuminated analytical reaction at a given reaction time. In preferred embodiments, the reaction mixture is subjected to at least one illuminated and non-illuminated period and allowed to proceed such that the time in which the reaction mixture is illuminated is less than a photo-induced damage threshold period.

Abstract: Compositions and methods for nucleic acid sequencing include template constructs that comprise double stranded portions in a partially or completely contiguous constructs, to provide for redundant sequence determination through one or both of sequencing sense and antisense strands, and iteratively sequencing the entire construct multiple times. Additional sequence components are also optionally included within such template constructs. Methods are also provided for the use and preparation of these constructs as well as sequencing compositions for their application.

Abstract: Provided are methods and compositions for the production of linear single-stranded nucleic acids, which can be used as templates in high-throughput sequencing systems. Also provided are methods and compositions for the production of closed single-stranded nucleic acid loops, which can be used as templates in high-throughput sequencing systems.

Abstract: Methods of preparing nucleic acid templates and providing the nucleic acid templates to low copy number reaction volumes are provided. Related compositions of nucleic acid templates are also provided.