Abstract: Described herein is a complex comprising multiple nucleic acid molecules that are hybridized together, each comprising, from 5? to 3?, a first complementary sequence, a spacer sequence and a second complementary sequence, and either/or a 5? end sequence that is 5? of the first complementary sequence and terminates in a 5? phosphate and a 3? end sequence that is 3? of the second complementary sequence and terminates in a 3? hydroxyl. In this complex: the first complementary sequence of one molecule is directly or indirectly hybridized with the second complementary sequence of another molecule in the complex and the spacer sequence and the 3? and/or 5? end sequences are single-stranded. Methods of making and using the complex are also provided.

Abstract: 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).

Abstract: Provided herein is probe system comprising: a population of nucleic acid molecules that have an extendible end, a first set of barcoded particles that each have a nucleotide sequence comprising: (i) a binding sequence that is complementary to the extendible end of the nucleic acid molecules, (ii) a unique particle identifier sequence, and (iii) a first template sequence, and a second set of barcoded particles that each have a nucleotide sequence comprising: (i) the first template sequence and (ii) a unique particle identifier sequence. In use, extension of the nucleic acid molecules using the first set of barcoded particles of as a template produces extensions products that contain the complement of a unique particle identifier sequence of a particle and the complement of the first template sequence. Methods of using the probe system to map binding events in or on a cellular sample are also provided.