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PubMed1976

Cardiac and skeletal muscle acid-base composition during metabolic acidosis in dogs.

Nephrectomized, open chested dogs were infused with 25-30 ml.kg(-1) body weight of 0.15 M NaCl (group I), 0.15 MHCl (Group II) or 0.3 M lactic acid (Group) III). Pulmonary ventilation was maintained constant in the three groups. Intracellular pH was calculated with the CO2 method. No significant intracellular or extracellular acid-base changes were produced in Group I. A similar degree of extracellular acidosis was achieved in Groups II and III. In spite of constant arterial PCO2, the PCO2 of mixed, coronary sinus and femoral vanous blood increased moderately after the infusion in Groups II and III. It was calculated that less than half of the HCl acid infused remained in the extracellular space. However, no significant changes were observed in the acid-base composition of skeletal muscle in either Group II or III. Comparison of the cardiac muscle cell acid-base composition of Group I with that of Groups II and III whows that metabolic acidosis of the degree and duration produced in these experiments does not produce appreciable myocardial acidosis.

Acid-Base Equilibrium↗
PubMed1991

A simple and rapid experimental protocol for studies of nucleic acids metabolism and their base composition.

A suitable, simple and rapid protocol for metabolic studies of nucleic acids and determining their base composition, using reversed-phase high-performance liquid chromatography is described. Modified classic methods of isolation of the nucleic acids fraction from a biological material, in our particular case Artemia sp., were used. Then analysis of their constituents and the incorporated radioactivity, after hydrolytic processes, was performed by high-performance liquid chromatography under isocratic conditions, with 9 min total retention time. This method may be applied in several aspects of nucleic acids research, such as molecular cloning or metabolic and phylogenetic studies.

Animals↗
PubMedDate not supplied

[Base composition and DNA content in single-cell Cyanobacteria].

The base composition and DNA content were determined in 19 strains of cyanobacteria. The content of GC varied within the range of 33.6 to 70.7 mol%, and the content of DNA, from 1.05 X 10(-14) to 28.7 X 10(-14) g per cell. The latter parameter almost directly depended on the cell volume. The cultures were subdivided into six groups according to the results obtained.

Bacteria↗
PubMed1990

Rapid procedure to determine the DNA base composition from small amounts of gram-positive bacteria.

A universal rapid procedure to determine the DNA base composition (mol% guanine + cytosine) of Gram-positive bacteria is described. Cells of Gram-positive bacteria were lysed with achromo-peptidase and the mol% G + C of their DNAs were determined by using high performance liquid chromatography. One ml of a Gram-positive bacterial suspension which matched MacFarland No. 3 standard turbidity was sufficient to determine the mol% G + C within 3 h.

Base Composition↗
PubMed1979

DNA chain length markers and the influence of base composition on electrophoretic mobility of oligodeoxyribonucleotides in polyacrylamide-gels.

The specific influence of the four nucleobases on electrophoretic mobility of oligodeoxyribonucleotides in polyacrylamide-gels under denaturing and nondenaturing conditions has been investigated using homooligomers from the four deoxyribonucleotides as chain length standards. Homooligomers of same chain lengths exhibit remarkable differences in mobility. Specific retardation of any other oligonucleotide investigated was found to be mainly dependent on base composition but not on sequence. A simple procedure is presented for calculating mobilities relative to the standards on denaturing gels. This allows a reliable identification of oligonucleotides on acrylamide-gels by exact chain length determination with respect to base composition and furthermore a detailed interpretation of complex reaction mixtures. The homooligomers also show the same differences in mobility on nondenaturing gels. The significance of this effect for strand separation is discussed.

Base Sequence↗
PubMed1969

Deoxyribonucleic acid base composition in the taxonomy of Staphylococcus.

Twenty-four strains of Staphylococcus aureus, including eight known mutants of S. aureus and strains growing under a variety of environmental conditions or exposed to a number of physical and chemical agents, maintained a remarkably narrow range of guanine plus cytosine (GC) content (32.4 to 35.1%). The wide range of GC content (30.7 to 40%) reported in the literature was due to the variety of methods and calculations used rather than to any substantial variation in base composition. The UV-2 "mutant" (ATCC 13680) with a GC content of 67.6% reported to be derived from S. aureus (ATCC 13679) was a species of Corynebacterium. The data presented were consistent with the concept that base composition changes only to a very slight degree by mutation.

Bacteriological Techniques↗
PubMed1984

DNA base composition, DNA-DNA homology and long-chain fatty acid studies on streptococcus thermophilus and Streptococcus salivarius.

DNA base composition, DNA-DNA homology and long-chain fatty acid studies were performed on Streptococcus thermophilus and Streptococcus salivarius. These species possess similar mol % G + C values (about 37 to 41), long-chain fatty acid profiles and belong to a single DNA homology group. On the basis of the present and earlier studies it is proposed that Streptococcus thermophilus (Orla-Jensen) be reclassified as Streptococcus salivarius subsp. thermophilus comb. nov.

Base Composition↗
PubMed1985

A microanalytical procedure for determination of the base composition of DNA.

A new procedure for the determination of the percentage guanine plus cytosine (% G+C; mol/100 mol) values of microquantities of DNA is described. Its principle is a DNA-polymerase-I-directed nick translation of DNA in the presence of dGTP, dTTP, [3H]dCTP, and [alpha-32P]dATP. Kinetics experiments indicate that the plateau value is reached in about 20 min of incubation under our experimental conditions. Percentage G+C is obtained from the linear relation 1/(% G+C) = 0.01 K [32P]/[3H] + 0.01, where the ratio of trichloroacetic-acid-precipitable radioactivity is taken into account, the K value being determined for each experiment by using a few reference DNAs of known composition. This procedure has proven suitable for analysis of plasmidic, viral and cellular DNAs of different base composition (25-75% G+C), shape (linear and circular double-stranded DNA) and size (100-150 000 base pairs). Usual methods for % G+C analysis (buoyant density and melting temperature determinations) yield unreliable results in the presence of either modified or unusual bases: the double-labeling procedure is still valid under these conditions. The latter is, therefore, the method of choice for analysis or rare DNA species which are available in very small quantities (it requires amounts of DNA as low as 1 ng, i.e. several order of magnitude lower than those used for chromatographic analysis of DNA hydrolysates). Since the obtention of highly purified DNA is an essential prerequisite for the double-labeling procedure, a method for purification of bacterial DNA is detailed in the present work.

Base Composition↗
PubMed1984

23Na NMR relaxation study of the effects of conformation and base composition on the interactions of counterions with double-helical DNA.

NMR relaxation rates (T1(-1) and T2(-1)) have been determined for 23Na in aqueous salt solutions containing various types of helical double-stranded deoxyribonucleic acids. These measurements were performed on three synthetic polynucleotides having different overall conformations, poly-(dA-dT).poly(dA-dT) (alternating B-DNA), poly(dG-dC).poly(dG-dC) at low salt (B-DNA), and Br-poly(dG-dC).Br-poly(dG-dC) (left-handed Z-DNA), and on four types of natural DNA differing in base composition, Clostridium perfringens (26% GC), calf thymus (40% GC), Escherichia coli (50% GC), and Micrococcus lysodeikticus (72% GC). For all types of DNA investigated, except poly(dA-dT).poly(dA-dT), the 23Na NMR spectra measured at 21 degrees C and an applied field of 4.7 T are non-Lorentzian. These non-Lorentzian spectra were analyzed on the basis of the two-state model and the standard theory of nonexponential quadrupolar relaxation processes in order to obtain estimates of the correlation times (tau c) characteristic of the sodium nuclei associated with the various nucleic acids. All of the correlation times estimated in this way are in the range of nanoseconds. The magnitudes of these correlation times show a significant dependence on the overall conformation of the nucleic acid (B vs. Z) but not on its base composition. To investigate the concentration dependence of tau c, sodium or magnesium salts were added to solutions of Br-poly(dG-dC).Br-poly(dG-dC) (Z-DNA).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1978

Base composition changes in hepatocyte nuclei DNA of rats at different ages.

DNA extracted from isolated hepatic nuclei of rats at different aged (1 h, 6 and 30 days of life) has been characterized by (i) melting temperature, (ii) buoyant density, (iii) thermal denaturation on hydroxyapatite and (iv) nucleoside composition. The melting midpoint (Tm) determined spectrophotometrically in 0.1 X SSC (0.15 M NaCl/0.0015 M sodium citrate) is 71.9 +/- 0.4 for 1-h-old rats and decreases to 70.7 +/- 0.3 in 6-day-old animals. The buoyant densities of DNAs determined by CsCl on both native and alkaline-denaturated and reneutralized DNA were also found to decrease with age. Hydroxyapatite thermal denaturation of sonicated DNA confirmed the significant difference between the Tm values of 1-h-old and 6-day-old rats (86.5 +/- 0.5 and 85.2 +/- 0.1, respectively). The possibility that these differences in Tm values could be due to an increase in methyl bases, has been ruled out by the finding that the amount of [3H]methyl incorporated in relation to the DNA synthesis is constant at these two ages. The alternative possibility of a change in base composition has been tested by the chromatographic analysis of nucleosides. The dG + dC content is 0.433 +/- 0.003 in 1-h-old rats and decreases to 0.411 +/- 0.002 and to 0.403 +/- 0.005 in 6-day- and 30-day-old rats, respectively. The physiological significance of the different base composition is discussed in relation to the possibility that specific DNA sequences are synthesized during the non-premitotic synthesis which has been found to take place during the first 6 days of life.

Aging↗
PubMed1983

Effect of diet on plasma acid-base composition in normal humans.

Steady-state plasma and urine acid-base composition was assessed in 19 studies of 16 normal subjects who ingested constant amounts of one of three diets that resulted in different rates of endogenous noncarbonic acid production (EAP) within the normal range. Renal net acid excretion (NAE) was used to quantify EAP since the two variables are positively correlated in normal subjects. A significant positive correlation was observed between plasma [H+] and plasma PCO2, and between plasma [HCO3-] and plasma PCO2, among the subjects. Multiple correlation analysis revealed a significant interrelationship among plasma [H+], plasma PCO2, and NAE (r = 0.71, P less than 0.001), and among plasma [HCO3-], plasma PCO2, and NAE (r = 0.77, P less than 0.001). The partial correlation coefficients indicated a significant positive correlation between plasma [H+] and NAE, and a significant negative correlation between plasma [HCO3-] and NAE, when plasma PCO2 was held constant. These findings indicate that two factors influence the level at which plasma [H+] is maintained in normal subjects: (1) the steady-state rate of endogenous noncarbonic acid production, and (2) the setpoint at which plasma PCO2 is regulated by the respiratory system. Plasma [HCO3-] is also co-determined by these two factors. In disease states, therefore, both factors must be known before a disturbance in acid-base homeostasis can be excluded.

Acid-Base Equilibrium↗
PubMed1973

DNA base composition of rickettsiae.

There is a small but distinct difference in DNA base composition between the typhus and spotted fever groups of rickettsiae. The molar percentages of guanine plus cytosine for Rickettsia prowazeki, R. typhi, and R. canada are approximately 30, for R. rickettsi, R. conori, and R. akari they are about 32.5. The percentage for trench fever rickettsia, Rochalimaea quintana, is 38.6.

Animals↗
PubMed1991

Phenomenological theory of GC/AT pressure on DNA base composition.

We present a phenomenological theory expressing the constraints operating on the (G + C) contents of the three codon positions, i.e., first, second, and third bases of codons, by using the smallest number of constraint parameters having clear physical and genetic meaning. Theoretical curves displaying base composition at each of the three codon sites are given. The agreement between the theoretical curves and the data points of 1277 genes is quite good irrespective of the species from which the DNAs originated; the curves might be universal ones and the constraint parameters might have general biological meanings in relation to the DNA/RNA and protein functions.

Base Composition↗
PubMed1984

High performance liquid chromatography preparation of the molecular species of GM1 and GD1a gangliosides with homogeneous long chain base composition.

A semi-preparative, analytical high performance liquid chromatographic (HPLC) procedure is described for the isolation of molecular species of GM1 and GD1a gangliosides containing a single long chain base, C18 or C20 sphingosine, C18 or C20 sphinganine, each in its natural erythro or unnatural threo form. The threo forms were obtained from 2,3-dichloro-5,6-dicyanobenzoquinone/NaBH4 -treated gangliosides. The ganglioside molecular species separated by HPLC were analyzed for carbohydrate, fatty acid, and long chain base composition. In particular, long chain bases were submitted to gas-liquid chromatographic-mass spectrometric analyses as their trimethylsilyl (TMS) or N-acetyl-TMS derivatives, and chain length, presence or absence of C4-C5 double bond, and C-3 steric configuration were ascertained. The final preparations of individual molecular species of GM1 and GD1a gangliosides were more than 99% homogeneous in their saccharide moiety, contained a single long chain base (homogeneity higher than 99%), and had a fatty acid composition primarily of stearic acid (92 to 97%). All the individual molecular species of GM1 and GD1a gangliosides were also prepared in radioactive form by selective tritiation at C-3 of the long chain base. Their specific radioactivity ranged from 1.3 to 1.45 Ci/mmol. The availability of these molecular species of gangliosides is expected to facilitate studies aimed at ascertaining the role played by the hydrophobic portion in the functional behavior of gangliosides.

Chromatography, High Pressure Liquid↗
PubMed1970

Reexamination of the association between melting point, buoyant density, and chemical base composition of deoxyribonucleic acid.

The equations currently used for the calculation of the chemical base composition of deoxyribonucleic acid (DNA), expressed as moles per cent guanine plus cytosine (% GC), from either buoyant density (rho) or midpoint of thermal denaturation (T(m)) were recalculated by using only sets of data on DNA determined with the same strains. All available information from the literature was screened and supplemented by unpublished data. The results were calculated by regression and correlation analysis and treated statistically. From the data on 96 strains of bacteria, it was calculated that% GC = 2.44 (T(m) - 69.4). T(m) appears to be unaffected by the substitution of cytosine by hydroxymethylcytosine. This equation is also valid for nonbacterial DNA. From the data on 84 strains of bacteria, the relation% GC = 1038.47 (-1.6616) was calculated. The constants in this equation are slightly modified when data on nonbacterial DNA are included. Both correlations differ only slightly from those currently used, but now they lean on a statistically sound basis. As a control, the relation between rho and T(m) was calculated from data of 197 strains; it agrees excellently with the above two equations.

Bacteria↗