Abstract: Methods, compositions, and systems are provided that allow for reliable sequencing of the initial sequence region of a sequence of interest. The methods of the invention allow for more reliable barcoding of subpopulations of nucleic acids to be sequenced.

Abstract: Methods and systems for single molecule sequencing using concatemers of copies of sense and antisense strands. Concatemers are provided, for example, by carrying out rolling circle amplification on a circular molecule having sense and antisense regions to produce repeated copies of the sense and antisense regions connected by linking regions. The circular molecules can be produced by ligating hairpin adapters to each end of a double-stranded nucleic acid having a sense and antisense strand. The ligations can be carried out, for example using blunt end ligation. In some cases, a single molecule consensus sequence for a single template molecule is obtained. A single read from each template molecule can be obtained by comparing the sequence information of the sense and antisense regions.

Abstract: Compositions, methods and systems are provided for isolating DNA having a modified or unnatural base. Circular DNA fragments, each comprising a double stranded DNA central region and single stranded regions on the ends of the double stranded regions, are obtained. Some of the fragments have one or more modified or unnatural base. The DNA fragments are treated with a primer and a polymerase such that the polymerase extends the primer to copy at least one of the strand of the double stranded region. This results in rendering the other strand single stranded. A binding protein or antibody that is specific to the modified or unnatural base is then used to isolate strands containing the modified or unnatural bases. Methods for loading such complexes onto substrates and for single molecule sequencing of such complexes 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. Methods are provided that include linking forward and reverse strands of a double stranded segment to form circular template molecules, and obtaining sequence data from the circular template molecule to identify modified bases, for example including the use of bisulfite treatment. 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 and systems for single molecule sequencing using concatemers of copies of sense and antisense strands. Concatemers are provided, for example, by carrying out rolling circle amplification on a circular molecule having sense and antisense regions to produce repeated copies of the sense and antisense regions connected by linking regions. The circular molecules can be produced by ligating hairpin adapters to each end of a double-stranded nucleic acid having a sense and antisense strand. The ligations can be carried out, for example using blunt end ligation. In some cases, a single molecule consensus sequence for a single template molecule is obtained. A single read from each template molecule can be obtained by comparing the sequence information of the sense and antisense regions.

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, 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 isolating DNA having a modified or unnatural base. Circular DNA fragments, each comprising a double stranded DNA central region and single stranded regions on the ends of the double stranded regions, are obtained. Some of the fragments have one or more modified or unnatural base. The DNA fragments are treated with a primer and a polymerase such that the polymerase extends the primer to copy at least one of the strand of the double stranded region. This results in rendering the other strand single stranded. A binding protein or antibody that is specific to the modified or unnatural base is then used to isolate strands containing the modified or unnatural bases. Methods for loading such complexes onto substrates and for single molecule sequencing of such complexes are also provided.

Abstract: Computer systems, computer readable media, and computer methods for obtaining, calling, and assembling nucleic acid sequences are presented. In some aspects the invention includes the sequencing of template constructs that comprise double stranded portions in partially contiguous constructs, to provide for single molecule consensus sequence determination through one or both of sequencing sense and antisense strands in the same molecule.

Abstract: Methods obtaining a single molecule consensus sequence for a single template molecule, and for obtaining a plurality of single molecule consensus sequences for a plurality of single template molecules is provided. Template molecules having two complementary regions connected with a linker are sequenced. A single read from each template molecule can be obtained, the read containing sequence information for each of the complementary regions. Single molecule consensus sequences can be determined from these reads by comparing the sequence information of the two complementary regions.

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. Methods are provided that include linking forward and reverse strands of a double stranded segment to form circular template molecules, and obtaining sequence data from the circular template molecule to identify modified bases, for example including the use of bisulfite treatment. 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 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: Methods, compositions, and systems are provided that allow for reliable sequencing of the initial sequence region of a sequence of interest. The methods of the invention allow for more reliable barcoding of subpopulations of nucleic acids to be sequenced.

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 and systems for single molecule sequencing using concatemers of copies of sense and antisense strands. Concatemers are provided, for example, by carrying out rolling circle amplification on a circular molecule having sense and antisense regions to produce repeated copies of the sense and antisense regions connected by linking regions. The circular molecules can be produced by ligating hairpin adapters to each end of a double-stranded nucleic acid having a sense and antisense strand. The ligations can be carried out, for example using blunt end ligation. In some cases, a single molecule consensus sequence for a single template molecule is obtained. A single read from each template molecule can be obtained by comparing the sequence information of the sense and antisense regions.

Abstract: Computer systems, computer readable media, and computer methods for obtaining, calling, and assembling nucleic acid sequences are presented. In some aspects the invention includes the sequencing of template constructs that comprise double stranded portions in partially contiguous constructs, to provide for single molecule consensus sequence determination through one or both of sequencing sense and antisense strands in the same molecule.

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. Hook oligonucleotides are used to capture polymerase nucleic acid complexes where the nucleic acids comprise circular nucleic acids having a double stranded central region with hairpin regions on each end. Methods for loading such complexes onto substrates and for single molecule sequencing of such complexes are also provided.

Abstract: Methods obtaining a single molecule consensus sequence for a single template molecule, and for obtaining a plurality of single molecule consensus sequences for a plurality of single template molecules is provided. Template molecules having two complementary regions connected with a linker are sequenced. A single read from each template molecule can be obtained, the read containing sequence information for each of the complementary regions. Single molecule consensus sequences can be determined from these reads by comparing the sequence information of the two complementary regions.

Abstract: Methods, compositions, and systems are provided that allow for reliable sequencing of the initial sequence region of a sequence of interest. The methods of the invention allow for more reliable barcoding of subpopulations of nucleic acids to be sequenced.

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.