Provided herein is a method for mapping rolling circle amplification (RCA) products that contain unique identifier sequences. The method generally involves (a) producing a complex comprising population of grid oligonucleotide molecules and a population of RCA products that each have a unique RCA product identifier sequence, wherein the grid oligonucleotides are hybridized directly or indirectly via a splint to complementary sites in the RCA products; (b) extending the grid oligonucleotide molecules that are hybridized to two RCA products to add the complements of the unique RCA product identifier sequences from the two RCA products to the grid oligonucleotide molecules; (c) sequencing the extended grid oligonucleotides; (d) analyzing the sequences to identify which pairs of unique RCA product identifier sequence complements have been added onto the grid oligonucleotides; and (e) making one or more physical maps of the immobilized RCA products using the pairs of sequences identified in (d).

Methods of labelling one or more subcellular components (e.g., an organelle and/or subcellular region) in vivo are provided. Methods of labelling a protein in vivo are provided. Methods of determining a nucleic acid sequence in situ are also provided.

Methods of labelling one or more subcellular components (e.g., an organelle and/or subcellular region) in vivo are provided. Methods of labelling a protein in vivo are provided. Methods of determining a nucleic acid sequence in situ are also provided.

The present application provides methods for detecting a target nucleic acid molecule in a sample comprising contacting said sample with a ligatable probe comprising one or more parts and allowing said probe to hybridise to the target nucleic acid molecule, ligating any probe which has hybridised to the target nucleic acid molecule, amplifying the ligated probe, and detecting the amplification product, thereby to detect the target nucleic acid molecule, wherein said probes comprise at least one ribonucleotide at or near to a ligation site and/or wherein the probe or a probe part comprises an additional sequence 5′ to a target-specific binding site which is not hybridised to the target nucleic acid molecule upon hybridisation of the probe to the target nucleic acid molecule and forms a 5′ flap containing one or more nucleotides at its 3′ end that is cleaved prior to ligation, and methods of synthesising a DNA molecule with Phi29 DNA polymerase using a template nucleic acid molecule comprising at least one ribonucleotide. Probes for use in the detection methods are provided.

The present application provides methods for detecting a target nucleic acid molecule in a sample comprising contacting said sample with a ligatable probe comprising one or more parts and allowing said probe to hybridise to the target nucleic acid molecule, ligating any probe which has hybridised to the target nucleic acid molecule, amplifying the ligated probe, and detecting the amplification product, thereby to detect the target nucleic acid molecule, wherein said probes comprise at least one ribonucleotide at or near to a ligation site and/or wherein the probe or a probe part comprises an additional sequence 5′ to a target-specific binding site which is not hybridised to the target nucleic acid molecule upon hybridisation of the probe to the target nucleic acid molecule and forms a 5′ flap containing one or more nucleotides at its 3′ end that is cleaved prior to ligation, and methods of synthesising a DNA molecule with Phi29 DNA polymerase using a template nucleic acid molecule comprising at least one ribonucleotide. Probes for use in the detection methods are provided.

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.

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.

Provided are immune cell RNA sequencing methods. In some embodiments, the methods comprise producing a circularized DNA comprising a complementary DNA (cDNA) and a known heterologous sequence, wherein the cDNA is produced from an immune cell RNA. Such methods further comprise performing rolling circle amplification using the circularized DNA as template to produce a concatemer comprising repeating segments comprising the cDNA and the known heterologous sequence. Such methods further comprise sequencing the concatemer or fragments thereof. Also provided are methods comprising producing immune cell RNA sequencing reads using a R2C2 sequencing method, extracting HLA reads from the sequencing reads, and producing allele-specific HLA sequences from the extracted HLA reads. Also provided are computer-readable media, systems, compositions and kits that find use, e.g., in practicing the methods of the present disclosure.

Provided are immune cell RNA sequencing methods. In some embodiments, the methods comprise producing a circularized DNA comprising a complementary DNA (cDNA) and a known heterologous sequence, wherein the cDNA is produced from an immune cell RNA. Such methods further comprise performing rolling circle amplification using the circularized DNA as template to produce a concatemer comprising repeating segments comprising the cDNA and the known heterologous sequence. Such methods further comprise sequencing the concatemer or fragments thereof. Also provided are methods comprising producing immune cell RNA sequencing reads using a R2C2 sequencing method, extracting HLA reads from the sequencing reads, and producing allele-specific HLA sequences from the extracted HLA reads. Also provided are computer-readable media, systems, compositions and kits that find use, e.g., in practicing the methods of the present disclosure.

In some aspects, the present disclosure relates to methods for reducing the crowding of signals, for example optical crowding, that can occur when nucleic acids are detected in a sample in multiplex, which can make it difficult to resolve individual signals and can lead to a reduced dynamic range. In some aspects, the present disclosure relates to methods for reducing signal crowding in the detection of multiple target nucleic acid sequences in a sample, e.g., using hybridization probes, wherein signal crowding from said hybridization probes is reduced. The methods herein have particular applicability in the detection of barcode sequences by sequencing-by-hybridization (SBH) methods, including those relying on combinatorial labelling schemes and decoding of the barcodes by sequential cycles of decoding using hybridization probes. Also provided are kits comprising probes for use in such methods.