Improved compositions and methods for using modified non-retroviral reverse transcriptase to perform 3′ extension of a nucleic acid, employ non-templated deoxynucleotide addition to a single-stranded nucleic acid and/or synthesis of complementary DNA using non-complementary nucleic acids as primer and template (RNA- or DNA-templated DNA polymerase activity.

Improved compositions and methods for using modified non-retroviral reverse transcriptase to perform 3′ extension of a nucleic acid, employ non-templated deoxynucleotide addition to a single-stranded nucleic acid and/or synthesis of complementary DNA using non-complementary nucleic acids as primer and template (RNA- or DNA-templated DNA polymerase activity.

Provided herein, among other things, is a method for synthesizing spatially addressed nucleic acid barcodes in or on a cellular sample in situ. In some embodiments, the method may comprise: obtaining a cellular sample comprising nucleic acid molecules that are protected by a reversible terminator, deprotecting the nucleic acid molecules in a set of areas of the sample by selectively applying an external stimulus to the set of areas to produce deprotected nucleic acid molecules in the areas, applying a reversible terminator nucleotide to the cellular sample, resulting in addition of a reversible terminator onto the deprotected nucleic acid molecules, optionally removing any unreacted reversible terminator nucleotide from the sample, and repeating the steps one or more times.

Provided herein, among other things, is a method for synthesizing spatially addressed nucleic acid barcodes in or on a cellular sample in situ. In some embodiments, the method may comprise: obtaining a cellular sample comprising nucleic acid molecules that are protected by a reversible terminator, deprotecting the nucleic acid molecules in a set of areas of the sample by selectively applying an external stimulus to the set of areas to produce deprotected nucleic acid molecules in the areas, applying a reversible terminator nucleotide to the cellular sample, resulting in addition of a reversible terminator onto the deprotected nucleic acid molecules, optionally removing any unreacted reversible terminator nucleotide from the sample, and repeating the steps one or more times.

A minimal-copy-ratio of templates is a problem in detecting early stage cancer where minimal copies of somatic cancer-specific mutations are targeted in the presence of large copies of wildtype genome DNA, commonly a 1/10,000 or even less minimal-copy-ratios between the mutant target and wildtype control templates. To overcome this problem, delayed pyrophosphorolysis activated polymerization (delayed-PAP) was developed which can delay product accumulation of the wildtype control to a much later time or cycle, such as by 15 cycles or by 30,000 folds. In the multiplex format, delayed-PAP is particularly useful to amplify not only the wildtype control but also mutant target templates accurately and consistently in the minimal-copy-ratio situation.

Provided herein are compositions and methods for accurate and scalable Primary Template-Directed Amplification (PTA) nucleic acid amplification and sequencing methods, and their applications for research, diagnostics, and treatment.

Provided herein are compositions and methods for accurate and scalable Primary Template-Directed Amplification (PTA) nucleic acid amplification and sequencing methods, and their applications for research, diagnostics, and treatment.

A method for determining the presence of an allele, including (a) binding a polymerase to a double stranded nucleic acid that includes a primer hybridized to a template, the template including a first allele of a locus; (b) adding a nucleotide to the primer via catalytic activity of the polymerase, thereby producing an extended nucleic acid; (c) dissociating the polymerase from the extended nucleic acid; (d) detecting dissociation of the polymerase from the extended nucleic acid; and (e) comparing the dissociation of the polymerase from the extended nucleic acid to dissociation of the polymerase from a second double stranded nucleic acid, the second double stranded nucleic acid including a primer hybridized to the same position of the locus as the primer of the extended nucleic acid.

A method for determining the presence of an allele, including (a) binding a polymerase to a double stranded nucleic acid that includes a primer hybridized to a template, the template including a first allele of a locus; (b) adding a nucleotide to the primer via catalytic activity of the polymerase, thereby producing an extended nucleic acid; (c) dissociating the polymerase from the extended nucleic acid; (d) detecting dissociation of the polymerase from the extended nucleic acid; and (e) comparing the dissociation of the polymerase from the extended nucleic acid to dissociation of the polymerase from a second double stranded nucleic acid, the second double stranded nucleic acid including a primer hybridized to the same position of the locus as the primer of the extended nucleic acid.

Provided herein are oligomers, compositions, kits, and methods for capturing target polynucleotides, e.g., for downstream applications such as amplification, library preparation, or sequencing. In some embodiments, a capture oligomer is provided or used that comprises a capture sequence that is annealed to a complement that prevents capture until the complement is displaced in a target-polynucleotide dependent manner. In some embodiments, an amount of target polynucleotide is captured that is less than or equal to a predetermined amount.