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At least 19 recordsLinked to original sources
PubMed1979

[Cytochemical study of free-living flagellates of suborder Bodonina. I. Morphology and nucleic acids].

Nucleic acids (DNA and RNA) have been discovered in the kinetoplast of free-living Bodonina: Bodo caudatus, Pleuromonas jaculans, Rhynchomonas nasuta--by means of cytochemical methods. The kinetoplast has variable contents of nucleic acids whose chemoarchitectonics is due to their non-homogeneous distribution within the kinetoplast. The Feulgen reaction in the kinetoplast is more intensive than in the nucleus. Kinetoplast is closely connected with the cytoplasmic RNA metabolism. Many individuals of R. nasuta were found to have two kinetoplasts, no other signs of cell division being observed. P. jaculans has up to 45% of dyskinetoplastic forms.

Animals↗
PubMed1978

Breaking action of reductones related to ascorbic acid on nucleic acids.

The action of two types of ascorbate-related reductones on nucleic acids was investigated by comparison with that of ascorbic acid (AsA). Amino reductone (ScA) and thiol reductone (MHC) caused strandscissions in nucleic acids. This was confirmed by the fact that reductones lowered the viscosity of DNA solution and shifted the peaks of DNA and RNA to the low molecular side in centrifugal profile. Cu2+ strengthened their action as in the case of enediol reductones. The braking activity of thiol reductone is relatively wesk compared with those of amino and enediol reductones. The preferential degradation of spurinic acid was caused with amino and thiol reductones, suggesting that pyrimidine clusters in nucleic acids were susceptible to breakage.

4-Hydroxycoumarins↗
PubMed1978

Cytofluorometry of lymphocytes infected with Epstein-Barr virus: effect of phosphonoacetic acid on nucleic acid.

DNA synthesis in Epstein-Barr virus (EBV)-infected lymphocytes was inhibited by phosphonoacetic acid (PAA) as measured by [3H]thymidine incorporation. PAA, at a concentration of 200 microgram/ml, inhibited [3H]thymidine incorporation by human umbilical cord lymphocytes infected with EBV strain P94 but had little effect on DNA synthesis in mitogen-stimulated cells. Transformed cell lines did not develop from infected cord cell cultures treated with 100 microgram of PAA per ml. Cytofluorometric analysis showed marked increases in cellular nucleic acid content (RNA plus DNA) as early as 9 days after infection of cord cells in the absence of PAA and before significant enhancement of [3H]thymidine incorporation became apparent. Moreover, EBV led to increases in cellular nucleic acid even when 200 microgram of PAA per ml was added to cell cultures before infection. The apparent discrepancy between results obtained by [3H]thymidine incorporation and cytofluorometry is explained either by significant inhibition of cellular DNA polymerases by PAA or by a block at the G2 + M phase of the cell cycle. The data suggest that EBV initiates alterations in cellular nucleic acid synthesis or cell division without prior replication of viral DNA by virus-induced DNA polymerases.

Cell Transformation, Viral↗
PubMed1975

Uptake in vitro of nucleic acid precursors and nucleic acids by Zajdela ascitic hepatoma cells.

Zajdela ascitic hepatoma cells are shown to take up pyrimidine bases at much lower rates than obtained in slices from normal rat liver. The rates of uptake of adenine and uridine by the Zajdela cells are, however, as high as in the slices. Like the slices, again, the Zajdela cells take up E. coli RNA and DNA at very low rates but, unlike the slices, thses cells degrade rapidly the RNA taken up. The Zajdela cells resemble parenchymal cell suspensions derived from normal rat liver in regard to the uptake of pyrimidine bases and the ability to degrade heterologous RNA.

Adenine↗
PubMed1976

Utilization of dietary nucleic acid purines for nucleotide and nucleic acid synthesis in the mouse.

Three preparations of radioactive yeast nucleic acids were fed to mice. One was labeled predominantly in the guanine moiety, one was labeled predominantly in the adenine moiety, and in one adenine and guanine were labeled equally. Most of the nucleic acid purines produced by digestion were excreted in the urine. However, a small amount was utilized for nucleotide and nucleic acid synthesis in the mouse tissues. Small intestine, liver and skeletal muscle contained most of the purines that were retained in the tissues. Dietary nucleic acid adenine appeared to be utilized somewhat more efficiently than was dietary nucleic acid guanine.

Adenine↗
PubMed1977

Transport of amino acids and nucleic acid precursors in malarial parasites.

In vitro studies have shown that exogenously supplied amino acids are transferred into the malaria-infected cell, where they are incorporated into proteins. Most amino acids appear to enter the cell by facilitated or simple diffusion; however, the high distribution ratios seen in Plasmodium knowlesi-infected cells are difficult to explain on this basis. The changes (leakiness) observed in amino acid transport in P. lophurae infected cells are probably the result of ATP depletion in the host cell as well as the elaboration of plasmodial substances. Depletion of isoleucine, methionine, and cysteine from the medium strikingly depresses the in vitro growth of P. knowlesi. The degree of amino acid incorporation into the malaria-infected cell is not correlated with the amount of a particular amino acid in the host cell haemoglobin, the decline of that amino acid in the plasma of infected animals, or the ratio of free amino acids of the erythrocyte to those of the plasma. In erythrocyte-"free" P. lophurae, carrier-mediated transport is apparently limited to a small number of amino acids; all others seem to enter by simple diffusion.Malaria-infected erythrocytes transport exogenously supplied purines at substantially higher rates than uninfected red cells. The preferred purines are adenosine, hypoxanthine, and inosine. The only pyrimidine incorporated is orotic acid. Thymidine, cytidine, and uridine do not readily enter the red cell, and incorporation does not take place because the parasites lack the appropriate enzyme for conversion to nucleotides. Erythrocyte-"free" P. berghei and P. lophurae take up purines and orotic acid. It has been suggested that in vivo the preferred purines are hypoxanthine and inosine, and that the transport locus for erythrocytes is specific for 6-oxopurines. Similar results of purine incorporation are reported for the insect stages of P. cynomolgi and P. berghei, although transport studies have not been carried out.

Amino Acids↗
PubMed1978

Amino acid-directed nucleic acid synthesis. A possible mechanism in the origin of life.

The fact that proteins contain only alpha-amino acids and that protein structure is determined by 3' leads to 5' linked ribonucleotides is postulated to be the result of the copolymerization of these molecules in the prebiotic environment. Ribonucleotides therefore represent partial degradation products and proteins represent a side reaction developing from copolymerization. The basic structural unit of copolymerization is a nucleotide substituted with an amino acid at the 2' postion. Characteristics of modern amino and ribonucleic acid structure are all consistent with and necessary for this hypothesis. The characteristics and individual base assignemnts of the code also provide strong support for origin from the postulated copolymers. All characteristics of the code can be accounted for by this single hypothesis.

Amino Acids↗
PubMed1979

Nucleic acid homology studies of viral nucleic acids in idiopathic Parkinson's disease.

Reassociation kinetics analyses with radioiodinated herpes simplex type 1 DNA and influenza A/NWS RNA were performed in the presence of tissue nucleic acids from defined loci of the brains of nine patients with idiopathic Parkinson's disease, one normal control brain, and the brains of uninfected mice or mice infected with either herpes simplex type 1 virus or influenza A/NWS virus. Herpes simplex type 1 DNA was detected by an increased reassociation rate in the herpes simplex type 1 virus-infected mouse brains. Influenza A/NWS RNA was detected by reassociation in the influenza A/NWS virus-infected mouse brains. Experimental limits for the detection of homologous nucleic acids are given for each separate experiment with human or mouse tissue. Within these detection limits, nucleic acids complementary to herpes simplex type 1 DNA or influenza A/NWS RNA were not detected in any of the brains of patients with idiopathic Parkinson's disease.

Brain↗
PubMed1979

The role of tyrosine in the association of proteins and nucleic acids. Specific recognition of single-stranded nucleic acids by tyrosine-containing peptides.

Oligopeptides containing tyrosyl, lysyl, and alanyl residues bind to polynucleotides and nucleic acids as shown by proton magnetic resonance, fluorescence spectroscopy, and difference absorption spectroscopy. Proton magnetic resonance data indicate that stacking of tyrosyl residues with nucleic acid bases takes place only in single-stranded structures (such as poly(A) or denatured DNA). Stacking interactions lead to a quenching of tyrosine fluorescence. However, the tyrosyl fluorescence of the peptides is quenched in their complexes with both single-stranded and double-stranded nucleic acids. A comparison of the behavior of homologous peptides containing Tyr, methoxytyrosine, and Phe leads to the conclusion that hydrogen bonding of tyrosine with bases or phosphates is not involved in the investigated complexes. An energy transfer mechanism from tyrosine to nucleic acid bases is proposed to account for fluorescence quenching in oligopeptide complexes with double-stranded DNAs. Due to the specificity of its stacking interaction for single-stranded nucleic acid structures, tyrosine might be involved through such interactions in the selective recognition of single strands by proteins.

Alanine↗
PubMed1979

Model studies of interactions between nucleic acids and proteins: hydrogen bonding of amides with nucleic acid bases.

The formation of hydrogen bonded complexes between nucleic acid bases and acetamide has been studied by nuclear magnetic resonance in CDC13 at different temperatures. Pairs of hydrogen bonds are formed when acetamide binds to nucleic acid bases. Thermodynamic parameters have been computed and compared to those obtained for the association of carboxylic acids with nucleic acid bases. The role of hydrogen bonded complexes in the association of proteins with nucleic acids is discussed.

Acetamides↗
PubMed1979

Models of interaction between nucleic acids and proteins. Hydrogen bonding of arginine with nucleic acid bases, phosphate groups and carboxylic acids.

Complex formation between the side chain of arginine and nucleic acid bases has been investigated by proton magnetic resonance in dimethylsulfoxide. Simultaneous formation of two hydrogen bonds leads to a selectivity of arginine interaction towards cytosine and guanine. A comparison is made of the interaction of arginine side chain with nucleic acid bases, phosphate and carboxylate anions. It is shown that interaction between carboxylate and arginine is stronger than between phosphate and arginine. These results are discussed with respect to the selective recognition of nucleic acid bases by arginine side chains and by the arginyl-glutamyl ion pair which could form in proteins interacting with nucleic acids.

Arginine↗