The present disclosure relates in some aspects to methods, probes, kits, and compositions for analysis of a target nucleic acid, such as in situ generation of a circular probe for detection of a target nucleic acid in a tissue sample.

Provided herein is a circular proximity ligation assay in which proximity-probes are employed as bridges to connect two free oligonucleotides via a dual ligation event, resulting in the formation of a circle. The circles are then quantified by, e.g., qPCR. The addition of an extra oligonucleotide is believed to enhance specificity by decreasing the probability of random background ligation events. In addition, circle formation may have selective advantages, as uncircularized DNA can be removed by a simple exonuclease treatment and it has streamlined the workflow by eliminating preamplification prior to qPCR.

Provided herein is a circular proximity ligation assay in which proximity-probes are employed as bridges to connect two free oligonucleotides via a dual ligation event, resulting in the formation of a circle. The circles are then quantified by, e.g., qPCR. The addition of an extra oligonucleotide is believed to enhance specificity by decreasing the probability of random background ligation events. In addition, circle formation may have selective advantages, as uncircularized DNA can be removed by a simple exonuclease treatment and it has streamlined the workflow by eliminating preamplification prior to qPCR.

The present invention relates to methods for determining endonuclease activity in a sample. In particular, the present invention relates to a method for determining viable pathogenic bacteria in a sample based on patterns of endonuclease activity.

There is provided a paper-based colorimetric sensor kit for quickly and simply diagnosing mercury in situ with a naked eye. The paper-based colorimetric sensor kit includes: a circular template for rolling circle amplification (RCA); a primer that does not hybridize to the circular template when a mercury ion is bonded to a primer that hybridizes to the circular template; a DNA polymerase; a sensing material kit including a nanoparticle probe labeled to a DNA coil formed in the circular template for RCA; and a radial chromatography paper.

There is provided a paper-based colorimetric sensor kit for quickly and simply diagnosing mercury in situ with a naked eye. The paper-based colorimetric sensor kit includes: a circular template for rolling circle amplification (RCA); a primer that does not hybridize to the circular template when a mercury ion is bonded to a primer that hybridizes to the circular template; a DNA polymerase; a sensing material kit including a nanoparticle probe labeled to a DNA coil formed in the circular template for RCA; and a radial chromatography paper.

The present disclosure relates in some aspects to methods for analyzing a target nucleic acid in a biological sample. In some aspects, the methods involve the use of a set of oligonucleotides, for example a set of two or more oligonucleotides, wherein one or more oligonucleotides comprises one or more photoreactive nucleotides, for analyzing target nucleic acids. In some aspects, the presence, amount, and/or identity of a target nucleic acid is analyzed in situ. Also provided are oligonucleotides, sets of oligonucleotides, compositions, and kits for use in accordance with the methods.

The present disclosure relates in some aspects to methods for analyzing a target nucleic acid in a biological sample. In some aspects, the methods involve the use of a set of oligonucleotides, for example a set of two or more oligonucleotides, wherein one or more oligonucleotides comprises one or more photoreactive nucleotides, for analyzing target nucleic acids. In some aspects, the presence, amount, and/or identity of a target nucleic acid is analyzed in situ. Also provided are oligonucleotides, sets of oligonucleotides, compositions, and kits for use in accordance with the methods.

This disclosure provides, inter alia, a probe system probe system for analyzing a nucleic acid sample. In some embodiments, the probe system may comprise: a set of identifier oligonucleotides of sequence B, a set of splint oligonucleotides of formula X′-A′-B′-Z′, wherein sequence A′ is complementary to a genomic fragment and sequence B′ is complementary to at least one member of the set of identifier oligonucleotides, and one or more probe sequences comprising X and Z. Each splint oligonucleotide is capable of hybridizing to the probe sequences, a member of the set of identifier oligonucleotides and a genomic fragment, thereby producing a ligatable complex of formula X-A-B-Z. The probe system can be used to identify a chromosome aneuploidy in cell free DNA, for example.

This disclosure provides, inter alia, a probe system probe system for analyzing a nucleic acid sample. In some embodiments, the probe system may comprise: a set of identifier oligonucleotides of sequence B, a set of splint oligonucleotides of formula X′-A′-B′-Z′, wherein sequence A′ is complementary to a genomic fragment and sequence B′ is complementary to at least one member of the set of identifier oligonucleotides, and one or more probe sequences comprising X and Z. Each splint oligonucleotide is capable of hybridizing to the probe sequences, a member of the set of identifier oligonucleotides and a genomic fragment, thereby producing a ligatable complex of formula X-A-B-Z. The probe system can be used to identify a chromosome aneuploidy in cell free DNA, for example.