scholarly journals A method for the selective extraction of histone fractions f2(a)1 and f2(a)2 from calf thymus deoxyribonucleoprotein at pH7

1967 ◽  
Vol 105 (2) ◽  
pp. 611-614 ◽  
Author(s):  
E W Johns
Keyword(s):  
Acid Solution ◽  
Selective Extraction ◽  
New Method ◽  
Guanidinium Chloride ◽  
Histone Fraction ◽  
Acetone Precipitation ◽  
Calf Thymus

1. A new method has been developed for the specific extraction of histone fraction f2(a) from calf thymus deoxyribonucleoprotein at pH7 by using a mixture of ethanol and guanidinium chloride. 2. Fraction f2(a) has been separated into the subfractions f2(a)1 and f2(a)2 by acetone precipitation from acid solution, and at pH7. 3. Modifications of existing electrophoretic methods are described that enable these fractions to be more easily characterized.

scholarly journals AMINOACRIDINE DYES AND THE SECONDARY STRUCTURE OF DNA IN SITU

1971 ◽  
Vol 19 (12) ◽  
pp. 761-765 ◽  
Author(s):  
MANUEL DIAZ ◽  
JOSE HIERRO ◽  
GRACIELA DEMICHELI DE DIAZ
Keyword(s):  
Secondary Structure ◽  
Acid Solution ◽  
Nitrous Acid ◽  
Deoxyribonucleic Acid ◽  
New Method ◽  
Green Fluorescence ◽  
Double Stranded Dna

A new method is proposed to study the secondary structure of deoxyribonucleic acid (DNA) in situ in fixed chromatin. It is based on acriflavine staining and on differentiation with a nitrous acid solution of the fixed cytologic preparation. The presence of green fluorescence after this treatment is regarded as indicative of double stranded DNA. Experiments are described with DNA-acriflavine mixtures in solution, DNA-agar models and cytologic preparations submitted to different pretreatments. The feasibility and limitations of the method are discussed in the light of the results reported upon.

The selective extraction of histones from rye chromatin

1976 ◽  
Vol 54 (9) ◽  
pp. 765-771 ◽  
Author(s):  
Hélène LaRue ◽  
Dominick Pallotta
Keyword(s):  
Selective Extraction ◽  
Histone H1 ◽  
The Other ◽  
Calf Thymus

The selective extraction of histones from rye chromatin was studied using three different methods. Extractions with NaCl–phosphate buffers atpH 5.5 gave results similar to those already obtained with other types of chromatin. Histone H1 was selectively extracted with 0.6 M NaCl –0.001 M PO4, while the selectivity of dissociation of the other fractions was reduced at higher NaCl concentrations. The use of phosphate–urea buffers at pH 5.5 also revealed that the histones were dissociated at the same concentrations as were calf thymus histones. Histone H1 was extracted with 0.5 M PO4 – 1 M urea; H1, H2A, and H2B were extracted with 0.8 M PO4 – 2 M urea; and all histones were removed with 0.8 M PO4 –5.3 M urea. It was, however, observed that the dissociated rye histones H2A and H2B were unstable in these buffers. This instability was maximum in the presence of 3 M urea, where both histones were absent from the extracted proteins and the residual nucleoproteins. Finally, a solution of 30% ethanol −0.35 M NaCl – 6 M urea produced a rye nucleoprotein fraction containing only histone H1.

Studies on nucleation from solution of some soluble inorganic salts

1970 ◽  
Vol 48 (18) ◽  
pp. 2896-2899 ◽  
Author(s):  
J. A. Velazquez ◽  
O. E. Hileman Jr
Keyword(s):  
Constant Temperature ◽  
Selective Extraction ◽  
New Method ◽  
Crystal Nucleation ◽  
Inorganic Salts ◽  
Nucleation Parameters ◽  
Solutions Of Electrolytes

Vonnegut's droplet technique in combination with selective extraction of solvent is reported as a new method for the study of nucleation from solution of soluble substances at constant temperature. The method is applied to studies on NH4Cl, NH4NO3, NH4SCN, (NH4)2Cr2O7, and K2Cr2O7,. The results are reported and various nucleation parameters are calculated and discussed in terms of the limitations of the Becker–Doring model of nucleation when it is applied to crystal nucleation from solutions of electrolytes.

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