Heteroduplex mobility assay, single-stranded conformation polymorphism and nucleotide sequencing were utilised to genotype human parvovirus B19 samples from Brazil and Paraguay. Ninety-seven serum samples were collected from individuals presenting with abortion or erythema infectiosum, arthropathies, severe anaemia and transient aplastic crisis; two additional skin samples were collected by bio...

Human piebald trait is an autosomal dominant defect in melanocyte development characterized by patches of hypopigmented skin and hair. Although the molecular basis of piebaldism has been unclear, a phenotypically similar "dominant spotting" of mice is caused by mutations in the murine c-kit protooncogene. In this regard, one piebald case with a point mutation and another with a deletion of c-ki...

We herein report the real-time observation of G-quadruplex formation by monitoring the G-quadruplex-induced global change of two duplexes incorporated in a DNA nanoscaffold. The introduced G-rich strands formed an interstrand (3 + 1) G-quadruplex structure in the presence of K(+), and the formed four-stranded structure was disrupted by removal of K(+). These conformational changes were visualiz...

With the advantages of conformational polymorphism and programmable sequence recognition, DNA has now become a powerful tool in nanostructure fabrication and nanodevice design. In most reported cases, DNA-based nanodevices are associated with a conformational switch driven by external fuels, such as DNA/RNA strands, acids/bases, enzymes, or chemical oscillators, in contact mode. These driving m...

Single-molecule experiments on single- and double-stranded DNA have sparked a renewed interest in the force versus extension of polymers. The extensible freely jointed chain (FJC) model is frequently invoked to explain the observed behavior of single-stranded DNA, but this model does not satisfactorily describe recent high-force stretching data. We instead propose a model (the discrete persiste...

Computer-based molecular modeling of single stranded polysaccharide chains is capable of a quantitative description of the polymer chain dimensions in dilute aqueous solution. The influence of glycosidic linkage position and stereochemistry on the local chain trajectory is now well understood. Some illustrative results of modeling of this sort are reported here. More recent efforts to understan...

The conformational changes suffered by full-length double-stranded DNA molecules from bac­ teriophage T7, due to their binding with the mutagenic dye proflavine (PF), has been studied by electron microscopy. The dye-bound DNA showed a smoother contour and a more compact con­ figuration in comparison with the dye-free native DNA. These changes resulted from the stretching, extension and charge-n...

BACKGROUND Chronic progressive external ophthalmoplagia (CPEO) is a phenotypic mitochondrial disorder that affects external ocular and skeletal muscles and is associated with a single or multiple mitochondrial DNA (mtDNA) deletions and also nuclear gene mutations. There are also some reports about the relationship between CPEO and the nuclear Twinkle gene which encodes a kind of mitochondrial p...

Electron microscopic and crystallographic data have shown that the gene 4 primase/helicase encoded by bacteriophage T7 can form both hexamers and heptamers. After cross-linking with glutaraldehyde to stabilize the oligomeric protein, hexamers and heptamers can be distinguished either by negative stain electron microscopy or electrophoretic analysis using polyacrylamide gels. We find that hexame...