OBJECTIVES: The present study was designed to systematically characterize the denaturation and the renaturation of double stranded DNA (dsDNA), which is suitable for DNA hybridization. METHODS: A series of physical and chemical denaturation methods were implemented on well-defined 86-bp dsDNA fragment. The degree of each denaturation was measured and the most suitable denaturation method was determined. DNA renaturation tendency was also investigated for the suggested denaturation method. RESULTS: Heating, beads mill, and sonication bath did not show any denaturation for 30 minutes. However probe sonication fully denatured DNA in 5 minutes. 1 mol/L sodium hydroxide (alkaline treatment) and 60% dimethyl sulfoxide (DMSO) treatment fully denatured DNA in 2-5 minutes. CONCLUSIONS: Among all the physical methods applied, the direct probe sonication was the most effective way to denature the DNA fragments. Among chemical methods, 60% DMSO was the most adequate denaturation method since it does not cause full renaturation during DNA hybridization.
Baths ; Dimethyl Sulfoxide ; DNA* ; Heating ; Hot Temperature ; Nucleic Acid Denaturation ; Sodium Hydroxide ; Sonication

High resolution melting (HRM), based on melting curve analysis, requires not only saturating dyes that fluoresce in the presence of double-stranded DNA, but also higher resolution detection equipment. The melting curve is a novel method for sequence matching, genotyping and mutation scanning. The technology is simple, accurate, rapid, closed-tube, low-cost, and high-throughput, which make it gain more and more applications. This review article presents the basic principles, key factors and both the advantage and limitations of HRM. The potential application is discussed in the study of molecular identity of traditional Chinese medicine.
DNA Mutational Analysis ; methods ; Drugs, Chinese Herbal ; classification ; Genotyping Techniques ; methods ; Medicine, Chinese Traditional ; Nucleic Acid Denaturation

OBJECTIVE: To develop the single-tube one-step methylation variable position (MVP) analysis technology-single-tube post-digestion PCR-melting curve analysis (PDP-MCA). METHODS: Based on differentially methylated region (DMR) reported previously as the model, a set of primers with different melting temperatures of products in the two sides of MVP were designed. By using the FastDigest methylation-sensitive restriction enzyme (MSRE), DNA digestion, multiplex amplification, MCA detection and MCA profiles were performed in a single reaction tube. Same samples (peripheral venous blood, semen, and vaginal fluid, 5 samples each type) were tested by single-tube one step MVP and traditional MSRE-PCR MCA technology. To verify the feasibility of this method, the results were compared with that of the traditional technology. The MCA/HRM profiles of different samples were analyzed and compared. RESULTS: When the melting temperature of the fragments had a differential of 2 degrees C, the MCA melting peaks separated well, and MCA detection after multiplex amplification was successful. The single-tube PDP-MCA assay was developed, which integrated multiple reactions (digestion, amplification and detection) into one tube. By this method, the sample-specific profiles and data were analyzed in 2 h, which is similar to that of the traditional method. The rapid classifications of the samples were also realized. CONCLUSION Multiplex MVPs can be analyzed in a single closed-tube. The single-tube PDP-MCA technology is a simple, fast, and automatable method. It can be used for detection of DNA methylation variations.
DNA/isolation & purification* ; DNA Methylation/genetics* ; DNA Primers/genetics* ; Humans ; Multiplex Polymerase Chain Reaction/standards* ; Nucleic Acid Denaturation

BACKGROUND: Nontuberculous mycobacteria (NTM) should be correctly identified to the species level, because of different treatment plans among NTM species. This study was performed to assess the usefulness of real-time PCR and melting curve analysis in the identification of NTM. METHODS: One hundred fifty-two clinical NTM isolates were identified to the species level by PCR-restriction fragment length polymorphism analysis (PRA). Those strains were then identified by multiplex real-time PCR and melting curve analysis on the 16S rRNA gene and hsp65 gene. RESULTS: In the 16S rRNA gene fragment analysis, M. abscessus-M. chelonae group showed melting point at temperatures above 65 degrees C and M. avium complex (MAC; M. avium and M. intracelluare) below 48 degrees C, which differentiated M. abscessus-M. chelonae group and MAC from other NTM. In the hsp65 gene fragment analysis, M. abscessus-M. chelonae group was clearly divided into M. abscessus type I, M. abscessus type II, and M. chelonae according to the melting points at 61.25 degrees C, 66.06 degrees C, and 57.58 degrees C, respectively. CONCLUSIONS: With the multiplex real-time PCR and melting curve analysis of 16S rRNA and hsp65 genes, M. abscessus and M. chelonae were readily identified and MAC were differentiated from other NTM. Especially, M. abscessus and M. chelonae, which were not differentiated from each other with the 16S rRNA gene fragment analysis, were identified with hsp65 gene fragment analysis.
Bacterial Proteins/genetics ; Chaperonins/genetics ; Computer Systems ; DNA, Bacterial/chemistry ; Mycobacteria, Atypical/genetics/*isolation & purification ; Nucleic Acid Denaturation ; Polymerase Chain Reaction/*methods ; RNA, Ribosomal, 16S/genetics

AIMTo examine the relationship between sperm DNA damage and sperm nuclear histone (H2B) staining.

METHODSWe evaluated sperm samples from 14 consecutive asthenoteratozoospermic infertile men and six consecutive fertile controls. Sperm nuclear histone (H2B) staining and sperm chromatin integrity (assessed by sperm chromatin structure assay and expressed using the percentage of (i) DNA fragmentation index [% DFI] and (ii) high DNA stainability [% HDS)]) were evaluated.

RESULTSHistone H2B immunocytochemistry demonstrated two nuclear staining patterns: (i) focal punctate staining; and (ii) diffuse staining. Infertile men had a higher mean percentage of spermatozoa exhibiting diffuse H2B staining than did fertile men (7.7% +/- 4.6% vs. 1.6% +/- 1.2%, respectively, P < 0.01). We observed significant relationships between the proportion of spermatozoa with diffuse nuclear histone staining and both sperm % DFI (r = 0.63, P < 0.01) and sperm %HDS (r = 0.63, P < 0.01).

CONCLUSIONThe data demonstrate that infertile men have a higher proportion of spermatozoa with diffuse histone H2B than do fertile men and suggest that sperm DNA damage might, at least in part, be due to abnormally high histone H2B levels.

Adult ; Chromatin ; chemistry ; metabolism ; DNA ; biosynthesis ; DNA Fragmentation ; Histones ; metabolism ; Humans ; Immunohistochemistry ; Infertility, Male ; metabolism ; Male ; Nucleic Acid Denaturation ; Sperm Motility ; physiology ; Spermatozoa ; metabolism

OBJECTIVETo establish a simple, rapid, inexpensive and sensitive method for detecting hot region for mutations in exon 7 of PAH gene.

METHODSHigh-resolution melting (HRM) technology was used to detect a c.728G>A mutation in exon 7 in 88 patients with classical type phenylketonuria. Suspected mutations were validated by direct DNA sequencing.

RESULTSThe results detected by HRM are in good agreement with the results obtained by direct sequencing.

CONCLUSIONHRM analysis is a simple, rapid, inexpensive and sensitive method for detecting hot mutational region in exon 7 of PAH gene.

Base Sequence ; Child ; Child, Preschool ; DNA Mutational Analysis ; methods ; Exons ; Female ; Humans ; Infant ; Infant, Newborn ; Male ; Mutation ; Nucleic Acid Amplification Techniques ; methods ; Nucleic Acid Denaturation ; Phenylalanine Hydroxylase ; genetics ; Phenylketonurias ; diagnosis ; genetics ; Transition Temperature

BACKGROUND: We developed and evaluated the utility of a multiplex real-time PCR assay that uses melting curve analysis and allows simultaneous identification of vancomycin-resistant genotypes and clinically relevant enterococci. METHODS: The specificity of the assay was tested using 4 reference strains of vancomycin-resistant enterococci (VRE) and 2 reference strains of vancomycin-susceptible enterococci. Ninety-three clinical isolates of enterococci with different glycopeptide-resistant phenotypes were genotyped and identified using a multiplex real-time PCR assay and melting curve analysis. RESULTS: Representative melting curves were obtained for Enterococcus faecium, Enterococcus faecalis, vanA-containing E. faecium, vanB-containing E. faecalis, Enterococcus gallinarum, and Enterococcus casseliflavus. Phenotypic and genotypic analysis of the isolates revealed same results for 82 enterococcal isolates, while in 4 isolates, the glycopeptide-resistant phenotypes were inconsistent with the glycopeptide-resistant genotypes and in the 4 other isolates, species could not be accurately identified. Three isolates with mixed strains, which were detected by the PCR assay, could not be correctly identified using phenotypic methods. CONCLUSIONS: VRE genotyping and identification of clinically relevant enterococci were rapidly and correctly performed using multiplex real-time PCR assay and melting curve analysis.
Bacterial Proteins/genetics ; Carbon-Oxygen Ligases/genetics ; DNA, Bacterial/genetics ; Enterococcus/genetics/*isolation &purification ; Enterococcus faecalis/genetics/isolation &purification ; Enterococcus faecium/genetics/isolation &purification ; Genotype ; Nucleic Acid Denaturation ; Peptide Synthases/genetics ; Phenotype ; *Polymerase Chain Reaction ; Vancomycin Resistance/*genetics

OBJECTIVETo detect the mutations of autosomal dominant polycystic kidney disease gene 2(PKD2)in Chinese.

METHODSThe white blood cell genomic DNA from patients of 94 Chinese autosomal dominant polycystic kidney disease(ADPKD) pedigrees was isolated and amplified by polymerase chain reaction(PCR). The PCR products were analyzed by denaturing high-performance liquid chromatography(DHPLC). The samples with abnormal profiles were sequenced.

RESULTSEight mutations were identified, including 2 nonsense mutations, 2 deletion mutations,1 insertion mutation and 3 missense mutations. Two nonsense mutations occurred in exon 5(1249C-->T) and exon 13(2407C-->T),both resulted in a stop codon. The insertion was in exon 2(636-637 ins T),and the deletion mutations were in exons 12(2348-2351 del AGAA) and 13(2401 delete A),resulting in the reading frame shift. Three missense mutations were in exons 1(G568-->A),4(C964-->T),and 5(G1168-->A), which caused amino acid changes (190Ala-->Thr,322Arg-->Trp,390Gly-->Ser).

CONCLUSIONThe method of DHPLC was used in detecting mutations successfully and 8 mutations in PKD2 were identified. It will be useful in the molecular diagnosis of ADPKD in advance of the cysts formation and birth.

Adolescent ; Adult ; Aged ; Aged, 80 and over ; Child ; Chromatography, High Pressure Liquid ; Female ; Humans ; Male ; Membrane Proteins ; genetics ; Middle Aged ; Mutation ; Nucleic Acid Denaturation ; Polycystic Kidney, Autosomal Dominant ; genetics ; TRPP Cation Channels

OBJECTIVETo assess the feasibility of high-resolution melting (HRM) analysis for screening patients with neonatal intrahepatic cholestasis caused by citrin deficiency (NICCD).

METHODSBased on previous studies on SLC25A13 gene in Chinese patients with NICCD, four hotspot mutations (851del4, 1638ins23, IVS6+5G>A and IVS16ins3kb) were selected. Results of the HRM analysis was validated using 50 negative controls and 20 patients with NICCD whose genotypes were confirmed previously by direct sequencing. With the established protocol, 171 suspected patients were enrolled. Samples with abnormal melting curves were further validated by DNA sequencing.

RESULTSHRM analysis can accurately determine the genotypes of all negative controls and patients. The sensitivity and specificity of the technique reached 100% (70/70). The melting curves of samples with the same genotype were highly reproducible. In 171 suspected patients, seven NICCD patients were detected by HRM. Identified mutations have included one case of 851del4 homozygote, one case of IVS6+5G>A heterozygote, 3 cases of 851del4 heterozygotes, one case of [IVS6+5G>A]+[ 851del4] and one case of [1638ins23+IVS16ins3kb]+[1638ins23]. All mutations were subsequently confirmed by DNA sequencing.

CONCLUSIONHRM analysis is a convenient, high-throughput and rapid technique for the screening of NICCD patients.

Anion Transport Proteins ; genetics ; Base Sequence ; Calcium-Binding Proteins ; deficiency ; China ; Citrullinemia ; diagnosis ; genetics ; metabolism ; DNA ; chemistry ; genetics ; Genetic Predisposition to Disease ; Genotype ; Humans ; Mitochondrial Proteins ; genetics ; Molecular Sequence Data ; Mutation ; Nucleic Acid Denaturation ; Organic Anion Transporters ; deficiency ; Sensitivity and Specificity

OBJECTIVETo establish a quantitative technique for assaying gene methylation in hepatocellular carcinoma (HCC) and evaluate its feasibility for clinical application.

METHODSFollowing bisulfite modification and PCR amplification, the fragments of CDKN2A and ACTB were cloned into plasmids to generate calibration curves using SYBR Green quantitative PCR, and then these two genes were quantitatively analyzed in 41 cases of HCC specimen.

RESULTSThe amplification curve, dissociation curve, calibration curve and electrophoresis analysis showed that SYBR Green fluorescent quantitative PCR could assay 10(2)-10(8) copies/microL of recombinant plasmids with high specificity, high sensitivity and a wide detection range. The tests on 41 cases of HCC specimens further confirmed its feasibility for quantitative analysis of methylation.

CONCLUSIONSYBR Green fluorescent PCR is an easy, fast and high-throughout quantitative tool, and it can be used for methylation analysis in basic research or clinical assay.

Actins ; genetics ; Biopsy ; Calibration ; Carcinoma, Hepatocellular ; genetics ; pathology ; DNA Methylation ; Feasibility Studies ; Female ; Fluorescence ; Genes, p16 ; Humans ; Luminescent Measurements ; Male ; Middle Aged ; Nucleic Acid Denaturation ; Polymerase Chain Reaction ; methods ; Sensitivity and Specificity ; Transition Temperature