scholarly journals Factors Determining Conformation of Nucleic Acids : With Special Reference to Effects of Glycosidic Conformation on Handedness of the Helix

1983 ◽  
Vol 103 (7) ◽  
pp. 701-718 ◽  
Author(s):  
SEIICHI UESUGI
1968 ◽  
Vol 109 (1) ◽  
pp. 75-78 ◽  
Author(s):  
Valda M. Craddock ◽  
A. R. Mattocks ◽  
P. N. Magee

1. To assess the significance of the methylation of nucleic acids known to be caused by certain carcinogens, the metabolic fate of 7[14C]-methylguanine was studied, with special reference to its possible incorporation into RNA and DNA. 2. The major part (approx. 95%) of the dose was excreted unchanged in the urine. A small amount of N-demethylation took place, as evidenced by the formation of radioactive adenine and guanine, and expiration of 14C-labelled carbon dioxide. No evidence was obtained for the direct incorporation of 7-methylguanine into systems synthesizing nucleic acids, i.e. RNA in liver, DNA in intestine or in the foetus.


Author(s):  
Norman Davidson

The basic protein film technique for mounting nucleic acids for electron microscopy has proven to be a general and powerful tool for the working molecular biologist in characterizing different nucleic acids. It i s possible to measure molecular lengths of duplex and single-stranded DNAs and RNAs. In particular, it is thus possible to as certain whether or not the nucleic acids extracted from a particular source are or are not homogeneous in length. The topological properties of the polynucleotide chain (linear or circular, relaxed or supercoiled circles, interlocked circles, etc. ) can also be as certained.


Author(s):  
J. A. Pollock ◽  
M. Martone ◽  
T. Deerinck ◽  
M. H. Ellisman

Localization of specific proteins in cells by both light and electron microscopy has been facilitate by the availability of antibodies that recognize unique features of these proteins. High resolution localization studies conducted over the last 25 years have allowed biologists to study the synthesis, translocation and ultimate functional sites for many important classes of proteins. Recently, recombinant DNA techniques in molecular biology have allowed the production of specific probes for localization of nucleic acids by “in situ” hybridization. The availability of these probes potentially opens a new set of questions to experimental investigation regarding the subcellular distribution of specific DNA's and RNA's. Nucleic acids have a much lower “copy number” per cell than a typical protein, ranging from one copy to perhaps several thousand. Therefore, sensitive, high resolution techniques are required. There are several reasons why Intermediate Voltage Electron Microscopy (IVEM) and High Voltage Electron Microscopy (HVEM) are most useful for localization of nucleic acids in situ.


Author(s):  
Dimitrij Lang

The success of the protein monolayer technique for electron microscopy of individual DNA molecules is based on the prevention of aggregation and orientation of the molecules during drying on specimen grids. DNA adsorbs first to a surface-denatured, insoluble cytochrome c monolayer which is then transferred to grids, without major distortion, by touching. Fig. 1 shows three basic procedures which, modified or not, permit the study of various important properties of nucleic acids, either in concert with other methods or exclusively:1) Molecular weights relative to DNA standards as well as number distributions of molecular weights can be obtained from contour length measurements with a sample standard deviation between 1 and 4%.


Author(s):  
Stephen D. Jett

The electrophoresis gel mobility shift assay is a popular method for the study of protein-nucleic acid interactions. The binding of proteins to DNA is characterized by a reduction in the electrophoretic mobility of the nucleic acid. Binding affinity, stoichiometry, and kinetics can be obtained from such assays; however, it is often desirable to image the various species in the gel bands using TEM. Present methods for isolation of nucleoproteins from gel bands are inefficient and often destroy the native structure of the complexes. We have developed a technique, called “snapshot blotting,” by which nucleic acids and nucleoprotein complexes in electrophoresis gels can be electrophoretically transferred directly onto carbon-coated grids for TEM imaging.


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