Solid-state 87Rb NMR signatures for rubidium cations bound to a G-quadruplex

ABSTRACTG-quadruplexes (Gq) are guanine-rich DNA structures formed by single-stranded DNA. They are of paramount significance to gene expression regulation, but also drug targets for cancer and human viruses. Current ensemble and single-molecule methods require fluorescent labels, which can affect Gq folding kinetics. Here we introduce, a single-molecule Gq nanopore assay (smGNA) to detect Gqs and kinetics of Gq formation. We use ~5 nm solid-state nanopores to detect various Gq structural variants attached to designed DNA carriers. Gqs can be identified by localizing their positions along designed DNA carriers establishing smGNA as a tool for Gq mapping. In addition, smGNA allows for discrimination of (un-)folded Gq structures, provides insights into single-molecule kinetics of G-quadruplex folding, and probes quadruplex-to-duplex structural transitions. smGNA can elucidate the formation of G-quadruplexes at the single-molecule level without labelling and has potential implications on the study of these structures both in single-stranded DNA and in genomic samples.

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Preparation of Thin Cadmium Telluride Samples for Electron Microscope Studies

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100052754 ◽

1974 ◽

Vol 32 ◽

pp. 548-549

Author(s):

T. J. Magee ◽

J. Peng ◽

J. Bean

Keyword(s):

Electron Microscope ◽

Sulfuric Acid ◽

Solid State ◽

Sample Preparation ◽

Cadmium Telluride ◽

Potassium Dichromate ◽

Optical Components ◽

The Past ◽

Solid State Devices

Cadmium telluride has become increasingly important in a number of technological applications, particularly in the area of laser-optical components and solid state devices, Microstructural characterizations of the material have in the past been somewhat limited because of the lack of suitable sample preparation and thinning techniques. Utilizing a modified jet thinning apparatus and a potassium dichromate-sulfuric acid thinning solution, a procedure has now been developed for obtaining thin contamination-free samples for TEM examination.

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The Collagenic Molecular Structural Unit of Solid State Complexes

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100066449 ◽

1971 ◽

Vol 29 ◽

pp. 478-479

Author(s):

Kenneth M. Richter ◽

John A. Schilling

Keyword(s):

Molecular Weight ◽

Solid State ◽

Structural Unit ◽

X Ray Diffraction ◽

X Ray ◽

Naoh Treatment

The structural unit of solid state collagen complexes has been reported by Porter and Vanamee via EM and by Cowan, North and Randall via x-ray diffraction to be an ellipsoidal unit of 210-270 A. length by 50-100 A. diameter. It subsequently was independently demonstrated by us in dog tendon, dermis, and induced complexes. Its detailed morphologic, dimensional and molecular weight (MW) aspects have now been determined. It is pear-shaped in long profile with m diameters of 57 and 108 A. and m length of 263 A. (Fig. 1, tendon, KMnO4 fixation, Na-tungstate; Fig. 2a, schematic of unit in long, C, and x-sectional profiles of its thin, xB, and bulbous, xA portions; Fig. 2b, tendon essentially unmodified by ether and 0.4 N NaOH treatment, Na-tungstate). The unit consists of a uniquely coild cable, c, of ṁ 22.9 A. diameter and length of 2580-3316 A. The cable consists of three 2nd-strands, s, each of m 10.6 A.

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