			Home About us Contact

Individual DNA Molecules (individual + dna_molecule)

Distribution by Scientific Domains

Polymers and Materials Science	50%
Life Sciences	33%

Selected Abstracts

Self-assembled pearling structure of long duplex DNA with histone H1

FEBS JOURNAL, Issue 9 2001
Yuko Yoshikawa
We report that complexes of giant DNA molecules with histone H1 proteins form a pearl necklace-like structure when the complexes are prepared by natural dilution from a high-salt solution (2 m NaCl) to a low-salt solution (0.2 m and 50 mm NaCl). We performed real-time observations on the conformational changes of individual T4 phage DNA (166 kb) molecules in bulk solution by fluorescence microscopy. To identify H1-binding regions on individual DNA molecules, we also performed immunofluorescence microscopic observations on the DNA,H1 complex spread on a glass surface. It was found that histone H1 binds DNA in a highly co-operative manner and is accompanied by local folding of the DNA. On the basis of the experimental observations and a theoretical simulation, we propose a self-assembling mechanism for the pearling structure. [source]

Sensors: DNA Sensing Using Nanocrystalline Surface-Enhanced Al2O3 Nanopore Sensors (Adv. Funct.

ADVANCED FUNCTIONAL MATERIALS, Issue 8 2010
Mater.
R. Bashir and co-workers report on page 1266 the development of solid-state Al2O3 nanopore sensors with enhanced surface properties for the real-time detection and analysis of individual DNA molecules. The cover illustrates the extension of coiled double-stranded DNA in the high-field region surrounding a nanocrystalline Al2O3 nanopore, followed by DNA transport. Nanocrystallite nucleation during pore formation helps enhance the single-molecule sensitivity and surface-charge characteristics of these devices and enables the potential fabrication of nanometer-scale metallic contacts in the pore. This technology finds broad application in drug screening, medicine, and bio-nanotechnology. [source]

DNA Sensing Using Nanocrystalline Surface-Enhanced Al2O3 Nanopore Sensors

ADVANCED FUNCTIONAL MATERIALS, Issue 8 2010
Bala Murali Venkatesan
Abstract A new solid-state, Al2O3 nanopore sensor with enhanced surface properties for the real-time detection and analysis of individual DNA molecules is reported. Nanopore formation using electron-beam-based decomposition transforms the local nanostructure and morphology of the pore from an amorphous, stoichiometric structure (O to Al ratio of 1.5) to a heterophase crystalline network, deficient in O (O to Al ratio of ,0.6). Direct metallization of the pore region is observed during irradiation, thereby permitting the potential fabrication of nanoscale metallic contacts in the pore region with application to nanopore-based DNA sequencing. Dose-dependent phase transformations to purely , and/or ,-phase nanocrystallites are also observed during pore formation, allowing for surface-charge engineering at the nanopore/fluid interface. DNA transport studies reveal an order-of-magnitude reduction in translocation velocities relative to alternate solid-state architectures, accredited to high surface-charge density and the nucleation of charged nanocrystalline domains. The unique surface properties of Al2O3 nanopore sensors make them ideal for the detection and analysis of single-stranded DNA, double-stranded DNA, RNA secondary structures, and small proteins. These nanoscale sensors may also serve as useful tools in studying the mechanisms driving biological processes including DNA,protein interactions and enzyme activity at the single-molecule level. [source]

Determination of haplotypes from single DNA molecules: a method for single-molecule barcoding,,

HUMAN MUTATION, Issue 9 2007
Ming Xiao
Abstract Determining the haplotypes in a diploid individual is a major technical challenge in genetic studies of human complex traits. Here we report a method of molecular haplotyping by directly imaging multiple polymorphic sites on individual DNA molecules simultaneously. DNA fragments amplified by long-range PCR were labeled with fluorescent dyes at each polymorphic site using a modified gap-filled padlock probe ligation approach. The labeled DNA molecules were then stretched into linear form on a functionalized glass surface and imaged with multicolor total internal reflection fluorescence (TIRF) microscopy. By determining the colors and positions of the fluorescent labels with respect to the backbone at polymorphic sites, the haplotype can be inferred accurately, in a manner similar to reading a barcode, even when the DNA fragments are not fully labeled. The feasibility of this technology is demonstrated by the determination of the haplotype of a 9.3-kbp DNA fragment containing four SNPs. Hum Mutat 28(9), 913,921, 2007. Published 2007 Wiley-Liss, Inc. [source]

DNA Sensors: Highly Sensitive, Mechanically Stable Nanopore Sensors for DNA Analysis (Adv. Mater.

ADVANCED MATERIALS, Issue 27 2009
27/2009)
A new solid state nanopore biosensor for the analysis of individual DNA molecules is reported by Rashid Bashir and co-workers on p. 2771. The cover illustrates the passage of double-stranded DNA through an Al2O3 nanopore sensor fabricated using ALD and e-beam-induced sputtering processes. Hexagonal ,-phase Al2O3 nanocrystallites form during pore formation as shown, improving the mechanical stability and sensitivity of these nanopore sensors. The CMOS-compatible nature of this process establishes this technology as a potential candidate for next-generation DNA sequencing. [source]

Direct Visualization of Abasic Sites on a Single DNA Molecule Using Fluorescence Microscopy,

PHOTOCHEMISTRY & PHOTOBIOLOGY, Issue 2 2002
Tamaki Hirose
ABSTRACT A new method was developed to allow direct visualization of damaged sites on individual DNA molecules. Fluorescence in situ hybridization on extended DNA molecules was modified to detect a single abasic site. Abasic sites were specifically labeled with a biotinylated aldehyde-reactive probe and fluorochrome-conjugated streptavidin. The light emitted by a single fluorochrome,DNA complex was calibrated. The number of abasic sites on the DNA molecule was estimated by counting each fluorochrome,DNA complex. The present study directly visualized and characterized the abasic sites of single DNA molecules. [source]