Abstract: The present disclosure relates in some aspects to methods and compositions for assessing performance of in situ analyte detection and/or platforms (e.g., methods, assays, workflows, and/or instruments for in situ analyte detection and/or sequencing). In some aspects, performance can be assessed for an individual platform, or the performance of two or more different platforms can be compared. In some aspects, assessing performance comprises a standardized in situ analyte detection workflow and analysis on a test biological sample comprising defined cell populations.

Abstract: Methods and compositions for performing base-by-base sequencing in situ in a cell or tissue sample that minimize optical crowding are described. In some embodiments, a sequencing primer hybridizes to a priming site 3? to an identifier sequence (e.g., a barcode sequence) in the sample such that the sequencing primer can be extended by a polymerase in a base-by-base fashion using the identifier sequence as a template. The sample can be contacted with nucleotides in a cyclic series of nucleotide incorporation or binding steps, and signals indicative of the incorporation or binding events can be detected to generate signal code sequences comprising a series of signal codes (corresponding to signals (ON signals), absence of signals (OFF signals), or a combination thereof) detected in the sequential cycles. Decoding of the identifier sequences based at least in part of the signal code sequences can be used to detect and locate the corresponding analytes.

Abstract: The present disclosure in some aspects relates to methods and compositions for accurately detecting and quantifying multiple analytes present in a biological sample. In some aspects, the methods and compositions provided herein address one or more issues associated with the stability and/or size of nucleic acid structures, such as RCPs, in the biological sample without the use of exogenously added oligonucleotide compaction probes. In some embodiments, provided herein are methods involving the use of self-hybridizing hybridizing regions for compacting and/or stabilizing nucleic acid concatemers (e.g., RCPs). In some embodiments, dynamic inter-strand annealing between tandem units of an RCP is used for compaction and/or stabilization. In some embodiments, short palindromic regions in an RCP are used for compaction and/or stabilization.

Abstract: The present disclosure in some aspects relates to methods and compositions for accurately detecting and quantifying multiple analytes present in a biological sample. In some aspects, the methods and compositions provided herein address issues associated with the heterogeneity of analyte abundance (e.g., gene expression levels) and variations among reactions at different locations of a sample (e.g., amplification reaction starting earlier at one location than another location). In some aspects, a method disclosed herein provides a tighter distribution of signal spot size and intensity in a sample, as compared to methods that result in a wide and heterogeneous size and intensity distribution of signal spots.

Abstract: Methods for index hopping sequence read filtering are provided. Each read in a plurality of reads from a multiplexed reaction comprises an insert portion, and first (molecular identifier) and second (sample index) non-insert portions. For each of a plurality of hashes, a hash data structure is formed with a representation of each read. Each representation comprises a hash of the first non-insert portion of the corresponding read. Read pairs are identified in the hash data structures. Each pair includes a first and second read sharing a common hash value but differing index values. An entry is added into a heterogeneous data structure, for each such pair, that includes the first and second non-insert portions of the first and second reads of the pair. Reads with first non-insert portion values appearing more than a threshold number of times in the heterogeneous data structure are removed from the plurality of reads.

Abstract: Provided herein are methods for analyzing a target nucleic acid, comprising contacting a target nucleic acid with a first polynucleotide and a second polynucleotide, and optionally one or more other polynucelotides such as a splint and/or a primer, to form a hybridization complex. In some embodiments, the first polynucleotide and the second polynucleotide are ligated to form a circular polynucleotide hybridized to the target nucleic acid, e.g., using DNA-templated ligation reaction(s). The circular polynucleotide and/or a product thereof (e.g., an RCA product) can be analyzed to analyze the target nucleic acid or a sequence thereof.