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Detection of nucleic acid targets using ramified rolling circle DNA amplification: a single nucleotide polymorphism assay model.

ABSTRACT: BACKGROUND: Isothermal amplification methods provide alternatives to PCR that may be preferable for some nucleic acid target detection tasks. Among current isothermal target detection methods, ramified rolling circle amplification (RAM) of single-stranded DNA circles that are formed by ligation of linear DNA probes (C-probes or padlock probes) offers a unique target detection system by linked primers and a simple amplification system that is unconstrained by the target's sequence context. Earlier implementations of RAM-based target detection were reported to be limited by background noise, due in part to unligated C-probe in the amplification reaction. We show here that a target-detection system using a biotinylated target-capture probe together with automated bead-handling reduces or eliminates background amplification noise. We demonstrate the system's performance by detection of a single-nucleotide polymorphism in human genomic DNA. METHODOLOGY: Target detection by RAM entails hybridization and ligation of a C-probe, followed by amplification and RAM signal detection. We evaluated RAM target detection in genomic DNA using recognition of a human Factor V gene single nucleotide polymorphism (G1691A) as a model. Locus-specific C-probes were annealed and ligated to genomic DNAs that represent the 3 possible genotypes at this locus, then ligated C-probes were amplified by real time RAM. The majority of the steps in the assay were performed with a magnetic bead-based chemistry on an automated platform. We show that the specificity of C-probe ligation permits accurate genotyping of this polymorphism. The assay as described here eliminates some of the background noise previously described for C-probe ligation, RAM amplification assays. CONCLUSION: The methods and results presented here show that a combination of C-probe detection, automated sample processing, and isothermal RAM amplification provide a practical approach for detecting DNA targets in complex mixtures.

SUBMITTER: Smith JH

PROVIDER: S-EPMC3664557 | biostudies-literature | 2013

REPOSITORIES: biostudies-literature

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Detection of nucleic acid targets using ramified rolling circle DNA amplification: a single nucleotide polymorphism assay model.

Smith James H JH Beals Thomas P TP

PloS one 20130527 5

<h4>Background</h4>Isothermal amplification methods provide alternatives to PCR that may be preferable for some nucleic acid target detection tasks. Among current isothermal target detection methods, ramified rolling circle amplification (RAM) of single-stranded DNA circles that are formed by ligation of linear DNA probes (C-probes or padlock probes) offers a unique target detection system by linked primers and a simple amplification system that is unconstrained by the target's sequence context. ...[more]

PMID: 23724122

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Project description:Nucleic acid amplification is a hugely important technology for biology and medicine. While the polymerase chain reaction (PCR) has been highly useful and effective, its reliance on heating and cooling cycles places some constraints on its utility. For example, the heating step of PCR can destroy biological molecules under investigation and heat/cool cycles are not applicable in living systems. Thus, isothermal approaches to DNA and RNA amplification are under widespread study. Perhaps the simplest of these are the rolling circle approaches, including rolling circle amplification (RCA) and rolling circle transcription (RCT). In this strategy, a very small circular oligonucleotide (e.g., 25-100 nucleotides in length) acts as a template for a DNA or an RNA polymerase, producing long repeating product strands that serve as amplified copies of the circle sequence. Here we describe the early developments and studies involving circular oligonucleotides that ultimately led to the burgeoning rolling circle technologies currently under development. This Account starts with our studies on the design of circular oligonucleotides as novel DNA- and RNA-binding motifs. We describe how we developed chemical and biochemical strategies for synthesis of well-defined circular oligonucleotides having defined sequence and open (unpaired) structure, and we outline the unusual ways in which circular DNAs can interact with other nucleic acids. We proceed next to the discovery of DNA and RNA polymerase activity on these very small cyclic DNAs. DNA polymerase "rolling circle" activities were discovered concurrently in our laboratory and that of Andrew Fire. We describe the surprising efficiency of this process even on shockingly small circular DNAs, producing repeating DNAs thousands of nucleotides in length. RNA polymerase activity on circular oligonucleotides was first documented in our group in 1995; especially surprising in this case was the finding that the process occurs efficiently even without promoter sequences in the circle. We describe how one can encode cleavable sites into the product DNAs and RNAs from RCA/RCT, which can then be resolved into large quantities of almost pure oligonucleotides. Our Account then proceeds with a summary describing a broad variety of tools and methods built in many laboratories around the rolling circle concept. Among the important developments are the discovery of highly efficient DNA polymerases for RCA; the invention of exponential ("hyperbranched") RCA amplification made possible by use of a second primer; the development of the "padlock" process for detection of nucleic acids and proteins coupled with RCA; the use of circular oligonucleotides as vectors in cells to encode biologically active RNAs via RCT; and the use of small DNA circles to encode and extend human telomeres. Finally, we finish with some ideas about where the field may go in the future.

Dataset Information

Detection of nucleic acid targets using ramified rolling circle DNA amplification: a single nucleotide polymorphism assay model.

Publications

Detection of nucleic acid targets using ramified rolling circle DNA amplification: a single nucleotide polymorphism assay model.

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