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Gale N, French DJ, Howard RL, McDowell DG, Debenham PG, Brown T. Rapid typing of STRs in the human genome by HyBeacon melting. Org Biomol Chem 2008; 6:4553-9. [PMID: 19039363 DOI: 10.1039/b813431f] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
A new method based on DNA melting has been developed for the rapid analysis of STRs in the human genome. The system is based on homogeneous PCR followed by fluorescence melting analysis and utilises a HyBeacon probe combined with a PCR primer-blocker oligonucleotide. The use of blockers of different length permits identification of the full range of common D16S539 repeats enabling detection of 99.8% of known alleles. The interrogation of STRs can be carried out on standard genetic analysis platforms and could be applied to other loci to form the basis of a bespoke high-throughput system for use in forensic analysis, particularly as fluorescent genetic analysis platforms are now available for high-resolution melting. This methodology may be suitable for rapid forensic DNA analysis at the point-of-arrest or in a custody suite where it is important to identify an individual from a small group of suspects/detainees.
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Affiliation(s)
- Nittaya Gale
- School of Chemistry, University of Southampton, Southampton, SO17 1BJ, UK
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52
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Astakhova IV, Korshun VA, Jahn K, Kjems J, Wengel J. Perylene attached to 2'-amino-LNA: synthesis, incorporation into oligonucleotides, and remarkable fluorescence properties in vitro and in cell culture. Bioconjug Chem 2008; 19:1995-2007. [PMID: 18771303 DOI: 10.1021/bc800202v] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
During recent years, fluorescently labeled oligonucleotides have been extensively investigated within diagnostic approaches. Among a large variety of available fluorochromes, the polyaromatic hydrocarbon perylene is an object of increasing interest due to its high fluorescence quantum yield, long-wave emission compared to widely used pyrene, and photostability. These properties make perylene an attractive label for fluorescence-based detection in vitro and in vivo. Herein, the synthesis of 2'- N-(perylen-3-yl)carbonyl-2'-amino-LNA monomer X and its incorporation into oligonucleotides is described. Modification X induces high thermal stability of DNA:DNA and DNA:RNA duplexes, high Watson-Crick mismatch selectivity, red-shifted fluorescence emission compared to pyrene, and high fluorescence quantum yields. The thermal denaturation temperatures of duplexes involving two modified strands are remarkably higher than those for double-stranded DNAs containing modification X in only one strand, suggesting interstrand communication between perylene moieties in the studied 'zipper' motifs. Fluorescence of single-stranded oligonucleotides having three monomers X is quenched compared to modified monomer (quantum yields Phi F = 0.03-0.04 and 0.67, respectively). However, hybridization to DNA/RNA complements leads to Phi F increase of up to 0.20-0.25. We explain it by orientation of the fluorochrome attached to the 2'-position of 2'-amino-LNA in the minor groove of the nucleic acid duplexes, thus protecting perylene fluorescence from quenching with nucleobases or from the environment. At the same time, the presence of a single mismatch in DNA or RNA targets results in up to 8-fold decreased fluorescence intensity of the duplex. Thus, distortion of the duplex geometry caused by even one mismatched nucleotide induces remarkable quenching of fluorescence. Additionally, a perylene-LNA probe is successfully applied for detection of mRNA in vivo providing excitation wavelength, which completely eliminates cell autofluorescence.
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Affiliation(s)
- Irina V Astakhova
- Nucleic Acid Center, Department of Physics and Chemistry, University of Southern Denmark, DK-5230 Odense M, Denmark
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53
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French DJ, Howard RL, Gale N, Brown T, McDowell DG, Debenham PG. Interrogation of short tandem repeats using fluorescent probes and melting curve analysis: a step towards rapid DNA identity screening. Forensic Sci Int Genet 2008; 2:333-9. [PMID: 19083844 DOI: 10.1016/j.fsigen.2008.04.007] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2008] [Revised: 03/31/2008] [Accepted: 04/23/2008] [Indexed: 10/22/2022]
Abstract
Current forensic DNA profiling methods rely on the analysis of samples at specialised laboratories with an average turnaround time of several days. The ability to rapidly determine a partial profile of short tandem repeats at the point-of-arrest would be of great benefit to police forces around the world, for example enabling a suspect to be rapidly included or excluded from an investigation. We have developed a homogeneous PCR method for the interrogation of STR loci utilising fluorescent oligonucleotide probes and melting curve analysis. Alleles of the D18S51, TH01 and D8S1179 loci were differentiated and identified on the basis of target length and probe melting temperature. Assay performance was evaluated by comparing melting peak data with the AmpFlSTR SGM Plus system. The method is compatible with direct analysis of unpurified buccal swab samples, enabling a partial STR profile to be generated within 1h.
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Affiliation(s)
- D J French
- Innovation and Support Team, LGC, Middlesex, UK.
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54
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Molecular probes: insights into design and analysis from computational and physical chemistry. Biochem Soc Trans 2008; 36:46-50. [PMID: 18208383 DOI: 10.1042/bst0360046] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The application of new molecular diagnostics to probe cellular process in vivo is leading to a greater understanding of molecular cytology at a sub-nanoscale level and is opening the way to individualized medicines. We review here three distinct fluorescence-based molecular probes, HyBeacons, split-probe exciplexes and GFP (green fluorescent protein)-based FRET (fluorescence resonance energy transfer) systems. Through this, we highlight the insights into the mechanism and design that a combined computational and experimental approach can yield.
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55
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Abstract
Scorpion probes, specific DNA probe sequences maintained in a hairpin–loop, can be modified to carry the components of an exciplex for use as a novel fluorescence-based method for specific detection of DNA. The exciplex partners (5′-pyrenyl and 3′-naphthalenyl) were attached to oligonucleotides via phosphoramidate links to terminal phosphate groups. Hybridization of the probe to a complementary target in a buffer containing trifluoroethanol produced an obvious fluorescence change from blue (pyrene locally excited state emission) to green (exciplex emission).
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56
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Socher E, Jarikote DV, Knoll A, Röglin L, Burmeister J, Seitz O. FIT probes: peptide nucleic acid probes with a fluorescent base surrogate enable real-time DNA quantification and single nucleotide polymorphism discovery. Anal Biochem 2008; 375:318-30. [PMID: 18249184 DOI: 10.1016/j.ab.2008.01.009] [Citation(s) in RCA: 83] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2007] [Revised: 01/08/2008] [Accepted: 01/08/2008] [Indexed: 11/19/2022]
Abstract
The ability to accurately quantify specific nucleic acid molecules in complex biomolecule solutions in real time is important in diagnostic and basic research. Here we describe a DNA-PNA (peptide nucleic acid) hybridization assay that allows sensitive quantification of specific nucleic acids in solution and concomitant detection of select single base mutations in resulting DNA-PNA duplexes. The technique employs so-called FIT (forced intercalation) probes in which one base is replaced by a thiazole orange (TO) dye molecule. If a DNA molecule that is complementary to the FIT-PNA molecule (except at the site of the dye) hybridizes to the probe, the TO dye exhibits intense fluorescence because stacking in the duplexes enforces a coplanar arrangement even in the excited state. However, a base mismatch at either position immediately adjacent to the TO dye dramatically decreases fluorescence, presumably because the TO dye has room to undergo torsional motions that lead to rapid depletion of the excited state. Of note, we found that the use of d-ornithine rather than aminoethylglycine as the PNA backbone increases the intensity of fluorescence emitted by matched probe-target duplexes while specificity of fluorescence signaling under nonstringent conditions is also increased. The usefulness of the ornithine-containing FIT probes was demonstrated in the real-time PCR analysis providing a linear measurement range over at least seven orders of magnitude. The analysis of two important single nucleotide polymorphisms (SNPs) in the CFTR gene confirmed the ability of FIT probes to facilitate unambiguous SNP calls for genomic DNA by quantitative PCR.
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Affiliation(s)
- Elke Socher
- Institut für Chemie, Humboldt-Universität zu Berlin, D-12489 Berlin, Germany
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57
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French DJ, McDowell DG, Debenham P, Gale N, Brown T. HyBeacon probes for rapid DNA sequence detection and allele discrimination. Methods Mol Biol 2008; 429:171-185. [PMID: 18695966 DOI: 10.1007/978-1-60327-040-3_12] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
HyBeacon probes are single-stranded oligonucleotides with one or more internal base(s) labeled with a fluorescent dye. When a probe forms a duplex with its target sequence, the level of fluorescence emission increases considerably. HyBeacons have been developed as new tools for rapid sequence detection and discrimination and have been employed in a wide variety of applications including infectious diagnostics and analysis of human polymorphisms. Single-labeled (FVG1) and dual-labeled (FVG11) probes were designed to analyze the factor V Leiden (R506Q) polymorphism which causes an increased risk of deep vein thrombosis and pulmonary embolism. Detection and identification of factor V alleles is performed by melting curve analysis and determination of probe melting temperature (T(m)). HyBeacon hybridization to the glutamine allele (Q) causes the formation of mismatched DNA duplexes that are detected through decreases in T(m). HyBeacon probes are included in homogeneous PCR assays to genotype samples with respect to the factor V polymorphism within 20 min, using purified DNAs and unpurified saliva/blood samples. This paper describes the preparation of homogeneous PCR assays, LightCycler target amplification, and subsequent melting curve analysis. This chapter also describes the use of homologous oligonucleotides and melting curve analysis as a method for probe evaluation.
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58
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Marras SAE. Interactive fluorophore and quencher pairs for labeling fluorescent nucleic acid hybridization probes. Mol Biotechnol 2007; 38:247-55. [PMID: 17985254 DOI: 10.1007/s12033-007-9012-9] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2007] [Accepted: 10/15/2007] [Indexed: 01/08/2023]
Abstract
The use of fluorescent nucleic acid hybridization probes that generate a fluorescence signal only when they bind to their target enables real-time monitoring of nucleic acid amplification assays. Real-time nucleic acid amplification assays markedly improves the ability to obtain qualitative and quantitative results. Furthermore, these assays can be carried out in sealed tubes, eliminating carryover contamination. Fluorescent nucleic acid hybridization probes are available in a wide range of different fluorophore and quencher pairs. Multiple hybridization probes, each designed for the detection of a different nucleic acid sequence and each labeled with a differently colored fluorophore, can be added to the same nucleic acid amplification reaction, enabling the development of high-throughput multiplex assays. In order to develop robust, highly sensitive and specific real-time nucleic acid amplification assays it is important to carefully select the fluorophore and quencher labels of hybridization probes. Selection criteria are based on the type of hybridization probe used in the assay, the number of targets to be detected, and the type of apparatus available to perform the assay. This article provides an overview of different aspects of choosing appropriate labels for the different types of fluorescent hybridization probes used with different types of spectrofluorometric thermal cyclers currently available.
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Affiliation(s)
- Salvatore A E Marras
- Public Health Research Institute and the Department of Microbiology and Molecular Genetics, UMDNJ-New Jersey Medical School, 225 Warren Street, Newark, NJ, 07103, USA.
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59
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Huang S, Salituro J, Tang N, Luk KC, Hackett J, Swanson P, Cloherty G, Mak WB, Robinson J, Abravaya K. Thermodynamically modulated partially double-stranded linear DNA probe design for homogeneous real-time PCR. Nucleic Acids Res 2007; 35:e101. [PMID: 17693434 PMCID: PMC2018630 DOI: 10.1093/nar/gkm551] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Real-time PCR assays have recently been developed for diagnostic and research purposes. Signal generation in real-time PCR is achieved with probe designs that usually depend on exonuclease activity of DNA polymerase (e.g. TaqMan probe) or oligonucleotide hybridization (e.g. molecular beacon). Probe design often needs to be specifically tailored either to tolerate or to differentiate between sequence variations. The conventional probe technologies offer limited flexibility to meet these diverse requirements. Here, we introduce a novel partially double-stranded linear DNA probe design. It consists of a hybridization probe 5′-labeled with a fluorophore and a shorter quencher oligo of complementary sequence 3′-labeled with a quencher. Fluorescent signal is generated when the hybridization probe preferentially binds to amplified targets during PCR. This novel class of probe can be thermodynamically modulated by adjusting (i) the length of hybridization probe, (ii) the length of quencher oligo, (iii) the molar ratio between the two strands and (iv) signal detection temperature. As a result, pre-amplification signal, signal gain and the extent of mismatch discrimination can be reliably controlled and optimized. The applicability of this design strategy was demonstrated in the Abbott RealTime HIV-1 assay.
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Affiliation(s)
- Shihai Huang
- Abbott Molecular Inc., Des Plaines, IL, USA and Abbott Diagnostics, AIDS Research and Retrovirus Discovery, Abbott Park, IL, USA
| | - John Salituro
- Abbott Molecular Inc., Des Plaines, IL, USA and Abbott Diagnostics, AIDS Research and Retrovirus Discovery, Abbott Park, IL, USA
| | - Ning Tang
- Abbott Molecular Inc., Des Plaines, IL, USA and Abbott Diagnostics, AIDS Research and Retrovirus Discovery, Abbott Park, IL, USA
| | - Ka-Cheung Luk
- Abbott Molecular Inc., Des Plaines, IL, USA and Abbott Diagnostics, AIDS Research and Retrovirus Discovery, Abbott Park, IL, USA
| | - John Hackett
- Abbott Molecular Inc., Des Plaines, IL, USA and Abbott Diagnostics, AIDS Research and Retrovirus Discovery, Abbott Park, IL, USA
| | - Priscilla Swanson
- Abbott Molecular Inc., Des Plaines, IL, USA and Abbott Diagnostics, AIDS Research and Retrovirus Discovery, Abbott Park, IL, USA
| | - Gavin Cloherty
- Abbott Molecular Inc., Des Plaines, IL, USA and Abbott Diagnostics, AIDS Research and Retrovirus Discovery, Abbott Park, IL, USA
| | - Wai-Bing Mak
- Abbott Molecular Inc., Des Plaines, IL, USA and Abbott Diagnostics, AIDS Research and Retrovirus Discovery, Abbott Park, IL, USA
| | - John Robinson
- Abbott Molecular Inc., Des Plaines, IL, USA and Abbott Diagnostics, AIDS Research and Retrovirus Discovery, Abbott Park, IL, USA
| | - Klara Abravaya
- Abbott Molecular Inc., Des Plaines, IL, USA and Abbott Diagnostics, AIDS Research and Retrovirus Discovery, Abbott Park, IL, USA
- *To whom correspondence should be addressed. +1 224 361 7310+1 224 361 7507
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60
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French DJ, Jones D, McDowell DG, Thomson JA, Debenham PG. Analysis of multiple single nucleotide polymorphisms closely positioned in the ovine PRNP gene using linear fluorescent probes and melting curve analysis. BMC Infect Dis 2007; 7:90. [PMID: 17683552 PMCID: PMC1994165 DOI: 10.1186/1471-2334-7-90] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2006] [Accepted: 08/03/2007] [Indexed: 11/17/2022] Open
Abstract
Background Resistance and susceptibility to scrapie has been associated with single nucleotide polymorphisms located within codons 136, 154 and 171 of the ovine prion protein gene (PRNP). Dual-labelled HyBeacon probes were developed to analyse single and clustered polymorphisms within these and neighbouring codons. Methods Extracted DNAs and unpurified blood samples were genotyped with respect to polymorphisms in PRNP codons 136, 141, 154 and 171. PCR amplicons were investigated using a LightTyper instrument, measuring the stability of probe/target hybridisation through peak melting temperatures and determining the sequence of nucleotides at polymorphic sites. Results The performance of HyBeacon assays was evaluated in a validation study comparing genotypes with those obtained using a primer extension assay (Sequenom MassEXTEND) analysed on a MALDI-ToF mass spectrometer. Over 12,000 sheep samples were successfully genotyped, reliably detecting A136, V136, T136, T137, L141, F141 R154, H154, L168, R171, Q171, H171 and K171 sequence variants using only 4 HyBeacon probes. Conclusion HyBeacon assays provide an extremely robust and accurate method for the analysis of single and clustered PRNP polymorphisms in a high-throughput format. The flexibility of the diagnostic tests ensures that samples are correctly genotyped even in the presence of additional sequence variations that flank the polymorphisms of interest. Such sequence variations may also be neutralised using universal bases such as 5-nitroindole if required.
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Affiliation(s)
| | - Dominic Jones
- LGC, Queens Road, Teddington, Middlesex, TW11 0LY, UK
| | | | - Jim A Thomson
- LGC, Queens Road, Teddington, Middlesex, TW11 0LY, UK
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61
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Grossmann T, Röglin L, Seitz O. Triplex-basierte “molecular beacons” als modulare Sonden zur DNA-Detektion. Angew Chem Int Ed Engl 2007. [DOI: 10.1002/ange.200700289] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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62
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Grossmann TN, Röglin L, Seitz O. Triplex Molecular Beacons as Modular Probes for DNA Detection. Angew Chem Int Ed Engl 2007; 46:5223-5. [PMID: 17535003 DOI: 10.1002/anie.200700289] [Citation(s) in RCA: 129] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- Tom N Grossmann
- Institut für Chemie der Humboldt-Universität zu Berlin, Brook-Taylor-Strasse 2, 12489 Berlin, Germany
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63
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Dose C, Seitz O. Single nucleotide specific detection of DNA by native chemical ligation of fluorescence labeled PNA-probes. Bioorg Med Chem 2007; 16:65-77. [PMID: 17499998 DOI: 10.1016/j.bmc.2007.04.059] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2006] [Revised: 04/05/2007] [Accepted: 04/27/2007] [Indexed: 10/23/2022]
Abstract
DNA-directed chemical ligations provide the opportunity to diagnose DNA sequences with very high sequence specificity. Fluorescent labels have been attached to reactive probes to enable the homogeneous detection of DNA and RNA. However, it has frequently been found that the attachment of fluorescent labels results in decreases of ligation fidelity. Herein we describe the development of a fluorogenic ligation reaction that provides for 10(2)-fold to perfect sequence selectivity. The reaction is based on the isocysteine-mediated native chemical PNA ligation. It is shown that DNA-induced rate accelerations of approximately 43.000-fold can be obtained through subtle variations of the ligation conditions. PNA-thioesters and isocysteine-PNA conjugates were labeled with FAM and TMR fluorophores, respectively. For gaining rapid synthetic access, a convenient on-resin labeling approach was developed. A new PNA monomer featuring an Alloc-protected lysine side chain was synthesized and coupled in solid-phase PNA synthesis. In the event of a ligation reaction the two fluorophores are brought into proximity. It is shown that fluorescence resonance energy transfer provides a positive fluorescence signal which is specific for product formation rather than for loss of starting materials. Single base mutations can be detected within minutes and with very high sequence selectivity at optimized conditions.
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Affiliation(s)
- Christian Dose
- Institut für Chemie der Humboldt-Universität zu Berlin, Brook-Taylor-Strasse 2, 12489 Berlin, Germany
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64
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Naphthalenyl- and anthracenyl-ethynyl dT analogues as base discriminating fluorescent nucleosides and intramolecular energy transfer donors in oligonucleotide probes. Tetrahedron 2007. [DOI: 10.1016/j.tet.2006.10.090] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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65
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Bethge L, Jarikote DV, Seitz O. New cyanine dyes as base surrogates in PNA: forced intercalation probes (FIT-probes) for homogeneous SNP detection. Bioorg Med Chem 2007; 16:114-25. [PMID: 17981472 DOI: 10.1016/j.bmc.2006.12.044] [Citation(s) in RCA: 70] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2006] [Accepted: 12/22/2006] [Indexed: 10/23/2022]
Abstract
Forced intercalation probes (FIT-probes) are nucleic acid probes, in which an intercalator cyanine dye such as thiazole orange (TO) serves as a replacement of a canonical nucleobase. These probes signal hybridization by showing strong increases of fluorescence. TO in FIT-probes responds to adjacent base mismatches by attenuation of fluorescence intensities at conditions where both matched and mismatched target DNA are bound. The interesting features of TO labeled FIT-probes posed the question whether the forced intercalation concept can be extended to other cyanine dyes of the thiazole orange family. Herein, we present the synthesis of three asymmetrical cyanine dyes and their incorporation into PNA-conjugates by means of both divergent and linear solid-phase synthesis. Melting analysis revealed that the DNA affinity of PNA probes remained high irrespective of the replacement of a nucleobase by the cyanines YO (oxazole yellow), MO or JO. Of the three new tested dye-PNA-conjugates, the YO-containing PNA has properties useful for homogeneous SNP detection. YO-PNA is demonstrated to signal the presence of fully complementary DNA by up to 20-fold enhancement of fluorescence. In addition, YO emission discriminates against single base mismatches by attenuation of fluorescence. Oxazole yellow (YO) as a base surrogate in PNA may prove useful in the multiplex detection of single base mutations at non-stringent conditions.
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Affiliation(s)
- Lucas Bethge
- Humboldt-Universität zu Berlin, Institut für Chemie, Brook-Taylor-Str. 2, 12489 Berlin, Germany
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66
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67
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Marras SAE, Tyagi S, Kramer FR. Real-time assays with molecular beacons and other fluorescent nucleic acid hybridization probes. Clin Chim Acta 2006; 363:48-60. [PMID: 16111667 DOI: 10.1016/j.cccn.2005.04.037] [Citation(s) in RCA: 178] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2005] [Revised: 04/22/2005] [Accepted: 04/27/2005] [Indexed: 10/25/2022]
Abstract
BACKGROUND A number of formats for nucleic acid hybridization have been developed to identify DNA and RNA sequences that are involved in cellular processes and that aid in the diagnosis of genetic and infectious diseases. METHODS The introduction of hybridization probes with interactive fluorophore pairs has enabled the development of homogeneous hybridization assays for the direct identification of nucleic acids. A change in the fluorescence of these probes indicates the presence of a target nucleic acid, and there is no need to separate unbound probes from hybridized probes. CONCLUSIONS The advantages of homogeneous hybridization assays are their speed and simplicity. In addition, homogeneous assays can be combined with nucleic acid amplification, enabling the detection of rare target nucleic acids. These assays can be followed in real time, providing quantitative determination of target nucleic acids over a broad range of concentrations.
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Affiliation(s)
- Salvatore A E Marras
- Department of Molecular Genetics, Public Health Research Institute, Newark, NJ 07103, USA
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68
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Hiratsuka M, Sasaki T, Mizugaki M. Genetic testing for pharmacogenetics and its clinical application in drug therapy. Clin Chim Acta 2006; 363:177-86. [PMID: 16126184 DOI: 10.1016/j.cccn.2005.05.047] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2005] [Accepted: 05/05/2005] [Indexed: 11/26/2022]
Abstract
There is wide individual variation in drug responses and adverse effects. As the main causes of the variation in drug responses, attention has focused on the genetic polymorphisms that encode metabolic enzymes regulating pharmacodynamics and receptors modulating the affinity with the responsive sites. Tailor-made drug therapy analyzes genetic polymorphisms involved in drug responses before drug administration and selects drugs and doses suitable for the individual genetic background. Establishment of tailor-made drug therapy is expected to contribute to medical economy by avoiding wasteful drug administration. To promote such medical practice, it is necessary to use simple genetic testing that is clinically convenient. Currently, genetic testing using real-time PCR has been frequently employed at laboratories with its clinical application anticipated. As to the many genes involved in drug responses, to date, the application of patient genetic information to tailor-made drug therapy has been achieved at the practical level. Information on pharmacogenetics will be a critical factor in medical practice in the near future.
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Affiliation(s)
- Masahiro Hiratsuka
- Department of Clinical Pharmaceutics, Tohoku Pharmaceutical University, Aoba-ku, Sendai, Japan
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69
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Hrdlicka PJ, Babu BR, Sørensen MD, Harrit N, Wengel J. Multilabeled pyrene-functionalized 2'-amino-LNA probes for nucleic acid detection in homogeneous fluorescence assays. J Am Chem Soc 2005; 127:13293-9. [PMID: 16173760 DOI: 10.1021/ja052887a] [Citation(s) in RCA: 123] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Homogeneous fluorescence assays for detection of nucleic acids are widely used in biological sciences. Typically, probes such as molecular beacons that rely on distance-dependent fluorescence quenching are used for such assays. Less attention has been devoted to tethering a single kind of fluorophores to oligonucleotides and exploiting hybridization-induced modulation of fluorescence intensity for nucleic acid detection. Herein, thermal denaturation experiments and fluorescence properties of oligodeoxyribonucleotides containing one or more 2'-N-(pyren-1-yl)carbonyl-2'-amino-LNA monomer(s) X are described. These pyrene-functionalized 2'-amino-LNAs display large increases in thermal stability against DNA/RNA complements with excellent Watson-Crick mismatch discrimination. Upon duplex formation of appropriately designed 2'-N-(pyren-1-yl)carbonyl-2'-amino-LNA probes and complementary DNA/RNA, intensive fluorescence emission with quantum yields between 0.28 and 0.99 are observed. Quantum yields of such magnitudes are unprecedented among pyrene-labeled oligonucleotides. Molecular modeling studies suggest that the dioxabicyclo[2.2.1]heptane skeleton and amide linkage of monomer X fix the orientation of the pyrene moiety in the minor groove of a nucleic acid duplex. Interactions between pyrene and nucleobases, which typically lead to quenching of fluorescence, are thereby reduced. Duplexes between multiple modified probes and DNA/RNA complements exhibit additive increases in fluorescence intensity, while the fluorescence of single stranded probes becomes increasingly quenched. Up to 69-fold increase in fluorescence intensity (measured at lambda(em) = 383 nm) is observed upon hybridization to DNA/RNA. The emission from duplexes of multiple modified probes and DNA/RNA at concentrations down to less than 500 nM can easily be seen by the naked eye using standard illumination intensities.
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Affiliation(s)
- Patrick J Hrdlicka
- Nucleic Acid Center, Department of Chemistry, University of Southern Denmark, DK-5230 Odense M, Denmark
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70
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Holland CA, Kiechle FL. Point-of-care molecular diagnostic systems — past, present and future. Curr Opin Microbiol 2005; 8:504-9. [PMID: 16098787 DOI: 10.1016/j.mib.2005.08.001] [Citation(s) in RCA: 122] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2005] [Accepted: 08/01/2005] [Indexed: 11/18/2022]
Abstract
The field of molecular diagnostics has greatly decreased the time it takes to identify infectious agents and to test their antimicrobial resistance. Portable devices are currently in development that can easily identify a variety of nucleic acid targets (either DNA or RNA) from multiple sample types in under an hour. This is done by a variety of methods including real-time polymerase chain reaction, probe-based assays, bioluminescence real-time amplification, and microarray or micro-pump technologies. These self-contained systems require only minimal training and perform all steps of the assay from extraction through detection with little or no operator intervention.
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Affiliation(s)
- Carol A Holland
- William Beaumont Hospital, Department of Clinical Pathology, Royal Oak, MI 48073-6769, USA.
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71
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Marks AHR, Bhadra PK, McDowell DG, French DJ, Douglas KT, Bichenkova EV, Bryce RA. Molecular basis of action of HyBeacon fluorogenic probes: a spectroscopic and molecular dynamics study. J Biomol Struct Dyn 2005; 23:49-62. [PMID: 15918676 DOI: 10.1080/07391102.2005.10507046] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
Abstract
HyBeacons, novel DNA probes for ultra-rapid detection of single nucleotide polymorphisms, contain a fluorophore covalently attached via a linker group to an internal nucleotide. As the probe does not require a quencher or self-complementarity to function, this study investigates the molecular-level mechanism underlying the increase of fluorescence intensity on hybridization of HyBeacons with target DNA. Spectroscopic ultraviolet-visible and fluorimetric studies, combined with molecular dynamics simulations, indicate projection of the fluorophore moiety away from the target-probe duplex into aqueous solution, although specific linker-DNA interactions are populated. Based on evidence from this study, we propose that for HyBeacons, the mechanism of increased fluorescence on hybridization is due to disruption of quenching interactions in the single-stranded probe DNA between the fluorophore and nucleobases. Hybridization leads to an extended linker conformation, removing the fluorophore from the immediate vicinity of the DNA bases.
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Affiliation(s)
- Abigail H R Marks
- Wolfson Centre for Structure-Based Rational Design of Molecular Diagnostics, School of Pharmacy and Pharmaceutical Sciences, University of Manchester, Manchester M13 9PL, UK
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72
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Csako G. Present and future of rapid and/or high-throughput methods for nucleic acid testing. Clin Chim Acta 2005; 363:6-31. [PMID: 16102738 DOI: 10.1016/j.cccn.2005.07.009] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2005] [Revised: 07/03/2005] [Accepted: 07/03/2005] [Indexed: 12/21/2022]
Abstract
BACKGROUND Behind the success of 'completing' the human genome project was a more than 30-year history of technical innovations for nucleic acid testing. METHODS Discovery of specific restriction endonucleases and reverse transcriptase was followed shortly by the development of the first diagnostic nucleic acid tests in the early 1970s. Introduction of Southern, Northern and dot blotting and DNA sequencing later in the 1970s considerably advanced the diagnostic capabilities. Nevertheless, it was the discovery of the polymerase chain reaction (PCR) in 1985 that led to an exponential growth in molecular biology and the introduction of practicable nucleic acid tests in the routine laboratory. The past two decades witnessed a continuing explosion of technological innovations in molecular diagnostics. In addition to classic PCR and reverse transcriptase PCR, numerous variations of PCR and alternative amplification techniques along with an ever-increasing variety of detection chemistries, closed tube (homogeneous) assays, and automated systems were developed. Discovery of real-time quantitative PCR and the development of oligonucleotide microarrays, the 'DNA chip', in the 1990s heralded the beginning of another revolution in molecular biology and diagnostics that is still in progress.
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Affiliation(s)
- Gyorgy Csako
- Department of Laboratory Medicine, W.G. Magnuson Clinical Center, National Institutes of Health, Bethesda, MD 20892-1508, USA.
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73
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Jarikote DV, Köhler O, Socher E, Seitz O. Divergent and Linear Solid-Phase Synthesis of PNA Containing Thiazole Orange as Artificial Base. European J Org Chem 2005. [DOI: 10.1002/ejoc.200500201] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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74
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Köhler O, Jarikote DV, Seitz O. Forced intercalation probes (FIT Probes): thiazole orange as a fluorescent base in peptide nucleic acids for homogeneous single-nucleotide-polymorphism detection. Chembiochem 2005; 6:69-77. [PMID: 15584015 DOI: 10.1002/cbic.200400260] [Citation(s) in RCA: 193] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Fluorescent base analogues in DNA are versatile probes of nucleic acid-nucleic acid and nucleic acid-protein interactions. New peptide nucleic acid (PNA) based probes are described in which the intercalator dye thiazole orange (TO) serves as a base surrogate. The investigation of six TO derivatives revealed that the linker length and the conjugation site decided whether a base surrogate conveys sequence-selective DNA binding and whether fluorescence is increased or decreased upon single-mismatched hybridization. One TO derivative conferred universal PNA-DNA base pairing while maintaining duplex stability and hybridization selectivity. TO fluorescence increased up to 26-fold upon hybridization. In contrast to most other probes, in which fluorescence is invariant once hybridization had occurred, the emission of TO-containing PNA probes is attenuated when forced to intercalate next to a mismatched base pair. The specificity of DNA detection is therefore not limited by the selectivity of probe-target binding and a DNA target can be distinguished from its single-base mutant under nonstringent hybridization conditions. This property should be of advantage for real-time quantitative PCR and nucleic acid detection within living cells.
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Affiliation(s)
- Olaf Köhler
- Institut für Chemie, Humboldt-Universität zu Berlin, Brook-Taylor-Strasse 2, 12489 Berlin, Germany
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75
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Abstract
Synthetic chemistry has been central to the design of modern methods of genetic analysis. In this article, we discuss the underlying chemistry and biophysical principles that have been used in the development of robust methods for the analysis of DNA in the diagnostic laboratory.
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Affiliation(s)
- Rohan T Ranasinghe
- School of Chemistry, University of Southampton, Highfield, Southampton, UK SO17 1BJ
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76
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Mackay IM, Arden KE, Nitsche A. Real-time Fluorescent PCR Techniques to Study Microbial-Host Interactions. METHODS IN MICROBIOLOGY 2004; 34:255-330. [PMID: 38620210 PMCID: PMC7148886 DOI: 10.1016/s0580-9517(04)34010-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
This chapter describes how real-time polymerase chain reaction (PCR) performs and how it may be used to detect microbial pathogens and the relationship they form with their host. Research and diagnostic microbiology laboratories contain a mix of traditional and leading-edge, in-house and commercial assays for the detection of microbes and the effects they impart upon target tissues, organs, and systems. The PCR has undergone significant change over the last decade, to the extent that only a small proportion of scientists have been able or willing to keep abreast of the latest offerings. The chapter reviews these changes. It discusses the second-generation of PCR technology-kinetic or real-time PCR, a tool gaining widespread acceptance in many scientific disciplines but especially in the microbiology laboratory.
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Affiliation(s)
- Ian M Mackay
- Clinical Virology Research Unit, Sir Albert Sakzewski Virus Research Centre, Royal Children's Hospital, Brisbane, Qld, Australia
- Clinical Medical Virology Centre, University of Queensland, Brisbane, Qld, Australia
| | - Katherine E Arden
- Clinical Virology Research Unit, Sir Albert Sakzewski Virus Research Centre, Royal Children's Hospital, Brisbane, Qld, Australia
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77
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Köhler O, Seitz O. Thiazole orange as fluorescent universal base in peptide nucleic acids. Chem Commun (Camb) 2004:2938-9. [PMID: 14680250 DOI: 10.1039/b308299g] [Citation(s) in RCA: 82] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Thiazole orange is shown to possess characteristics of a universal base while maintaining duplex stability. Its fluorescence properties allowed distinction between matched and single mismatched hybridisation.
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Affiliation(s)
- Olaf Köhler
- Institut für Chemie, Humboldt-Universität zu Berlin, Brook-Taylor-Str. 2, D-12489 Berlin, Germany
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78
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Abstract
Use of PCR in the field of molecular diagnostics has increased to the point where it is now accepted as the standard method for detecting nucleic acids from a number of sample and microbial types. However, conventional PCR was already an essential tool in the research laboratory. Real-time PCR has catalysed wider acceptance of PCR because it is more rapid, sensitive and reproducible, while the risk of carryover contamination is minimised. There is an increasing number of chemistries which are used to detect PCR products as they accumulate within a closed reaction vessel during real-time PCR. These include the non-specific DNA-binding fluorophores and the specific, fluorophore-labelled oligonucleotide probes, some of which will be discussed in detail. It is not only the technology that has changed with the introduction of real-time PCR. Accompanying changes have occurred in the traditional terminology of PCR, and these changes will be highlighted as they occur. Factors that have restricted the development of multiplex real-time PCR, as well as the role of real-time PCR in the quantitation and genotyping of the microbial causes of infectious disease, will also be discussed. Because the amplification hardware and the fluorogenic detection chemistries have evolved rapidly, this review aims to update the scientist on the current state of the art. Additionally, the advantages, limitations and general background of real-time PCR technology will be reviewed in the context of the microbiology laboratory.
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Affiliation(s)
- I M Mackay
- Clinical Virology Research Unit, Sir Albert Sakzewski Virus Research Centre and Department of Paediatrics, Royal Children's Hospital, Brisbane, Queensland, Australia.
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79
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Dobson N, McDowell DG, French DJ, Brown LJ, Mellor JM, Brown T. Synthesis of HyBeacons and dual-labelled probes containing 2'-fluorescent groups for use in genetic analysis. Chem Commun (Camb) 2003:1234-5. [PMID: 12809207 DOI: 10.1039/b302855k] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
An FMOC-protected 2'-hydroxyethyl uridine phosphoramidite has been used to synthesise fluorescein-labelled HyBeacon probes and "FAM-ROX" dual-labelled fluorogenic oligonucleotides.
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Affiliation(s)
- Neil Dobson
- Department of Chemistry, University of Southampton, Highfield, Southampton, UK SO17 1BJ
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80
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French DJ, Archard CL, Andersen MT, McDowell DG. Ultra-rapid DNA analysis using HyBeacon probes and direct PCR amplification from saliva. Mol Cell Probes 2002; 16:319-26. [PMID: 12477435 DOI: 10.1006/mcpr.2002.0425] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
We describe a novel probe technology, termed HyBeacons, which provides a new homogeneous method for fluorescence-based sequence detection and allele discrimination. Employing a single nucleotide polymorphism located in the N-acetyltransferase 2 gene as a model system, we demonstrate the utility of HyBeacon probes for rapid and reliable sequence analysis. We also demonstrate that homozygous and heterozygous samples may be accurately identified using a single HyBeacon oligonucleotide. Polymorphic DNA sequences were detected and differentiated by real-time PCR and melt peak methodologies, without performing extraction of genomic DNA prior to target amplification. Employing a combination of homogeneous HyBeacon analysis, the rapid thermal cycling conditions of the LightCycler and direct amplification from saliva, allowed samples to be genotyped within 30 min. Such rapid non-invasive diagnostic technologies may permit 'point-of-care' genetic testing to be performed in hospitals and doctor's surgeries.
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Affiliation(s)
- D J French
- BioAnalytical Innovations, LGC (Teddington) Ltd, Queens Road, Teddington, TW11 0LY, UK.
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