Incorporation Of Adenine Research Articles

Studies of metabolic alterations induced by steroids in murine lymphocytic leukemia cells in vitro

Triamcinolone acetonide, an effective inhibitor of the reproduction of L5178Y murine neoplastic lymphoblasts both in vivo and in minute amounts in cell culture, depressed in these cells: (a) the uptake of several amino acids into protein, (b) the incorporation of adenine into nucleic acids, and (c) the conversion of glucose to carbon dioxide. A study of the sequence of the inhibition of several metabolic events in steroid-treated cells in culture demonstrated that the conversion of glucose-U- 14C into 14CO 2 was depressed before significant alterations in the uptake of glycine into protein could be detected. The inhibitory effects appeared to be related to that type of steroid structure generally associated with anti-inflammatory and gluconeogenic, as well as anti-leukemic, activities. At comparable concentrations, steroids which exhibited primarily androgenic activity had no inhibitory effects on the reactions studied in these cells.

EFFECT OF RUST-INHIBITING COMPOUNDS ON THE METABOLISM OF WHEAT LEAVES

Healthy leaves of Little Club wheat (Triticum compactum Host.) and leaves infected by leaf rust (Puccinia recondita Rob. ex. Desm. race 5) were detached and floated for 3 days on solutions containing 10 p.p.m. canavanine, 0.1% azathymine, 0.125% dulcitol, and 0.1% methionine. Leaf samples were fed with uniformly labelled glucose for 24 hours, fractionated, and the C14-content of each fraction was determined. Compared with controls, canavanine slightly reduced the amount of C14in amino acids, nucleic acids, and proteins while 6-azathymine markedly reduced the amount of C14in nucleic acids and proteins. Treatment with dulcitol resulted in a lower recovery of C14from all fractions other than sugars while methionine had little effect on the distribution of C14from glucose. Quantitative analyses showed a marked increase in amino acids after canavanine, 6-azathymine, and methionine treatments and a reduced level of nucleic acids after treatment with canavanine and azathymine.Canavanine had no effect on the incorporation of arginine and glutamic acid into leaf proteins while 6-azathymine inhibited the incorporation of adenine into nucleic acids. It was not possible to relate the changes that occurred following these treatments to the in vivo metabolism of the rust fungus.

L’Action de l’irradiation ultraviolette sur le métabolisme des acides nucléiques dans l’embryon de Poulet

ABSTRACT The incorporation of labelled adenine in the neural plate of ultra-violet irradiated chick embryos has been studied. It has been confirmed that small doses of radiation inhibit the closure of the neural folds. The incorporation of adenine increases immediately after radiation and decreases one hour after the treatment. There is a significant increase of the mitotic index during this first hour. In the light of previous results it is possible to attribute the inhibition of closure of the neural folds to some alteration in the metabolism of nucleic acids or proteins.

Utilization of preformed purines by sarcoma 180 or hepatoma 134 cells treated with 6-chloropurine or a combination of 6-chloropurine and azaserine

The metabolism of preformed purines was compared in sarcoma 180 and hepatoma 134 ascites tumor cells exposed to either 6-chloropurine or a combination of chloropurine and azaserine. Marked alterations in purine utilization occurred in the drug-sensitive cells (sarcoma 180) treated with chloropurine. These were an increased incorporation of adenine and guanine into polynucleotide guanine, an increased conversion of guanine to acid-soluble adenine, and an increased conversion of hypoxanthine to both polynucleotide and acid-soluble adenine. Preformed purine metabolism of hepatoma 134, a neoplasm in which chloropurine did not enhance the growth-retarding properties of azaserine, proved to be relatively refractive to chloropurine. An increased conversion of preformed guanine to acid-soluble adenine occurred as a consequence of chloropurine treatment. Exposure of sarcoma 180 to a combination of chloropurine and azaserine increased the rate of conversion of preformed purines to adenine nucleotides over that found with chloropurine alone. Hepatoma 134 also responded to the drug combination by an increase in the rate of preformed purine conversion to adenine nucleotides. These reactions were interpreted as manifestations of compensatory responses to the stress of metabolic blocks on the pathway of purine synthesis de novo.

The metabolic characteristics of nucleolar, chromosonal, and cytoplasmic ribonucleic acid of Drosophila salivary glands.

Incorporation and retention of adenine-8-C(14) and of P(32)O(4) by nucleolar, chromosomal, and cytoplasmic RNA have been studied. Radioisotope concentrations were determined from autoradiographs, by grain counting, and RNA concentrations by microphotometry after basic staining. The relation between rates of RNA accumulation and rates of adenine incorporation was used to determine if synthesis was used to replace RNA which was lost from a fraction, and to obtain estimates of turnover rate. Nucleolar incorporation patterns indicate its incorporation is independent of growth, and there is complete turnover of the fraction in an hour or less. Nucleolar turnover is attributed to degradation of RNA within the nucleolus rather than to movement of intact molecules from the nucleolus. Chromosomal RNA reaches a much lower maximum specific activity than nucleolar, and a slightly higher maximum than cytoplasmic RNA. It showed faster incorporation than cytoplasmic RNA while accumulating RNA at the same rate as the cytoplasm, suggesting chromosomal RNA turnover. No evidence of cytoplasmic RNA turnover was found: rate of incorporation and rate of growth were correlated, and retention studies detected no decrease in amount of RNA-C(14), RNA-P(32), or RNA. Different ultimate precursors are indicated for nucleolar and non-nucleolar RNA by the observation that the nucleolar precursor is labeled before the precursor of non-nucleolar RNA.

Relation between cell growth and cell division: IV. The synthesis of DNA, RNA, and protein from division to division in Tetrahymena

The incorporation of 14C methionine into protein, 14C adenine into RNA, and tritium-thymidine into DNA has been followed autoradiographically over the cell cycle in small groups of Tetrahymena in synchrony. 14C methionine incorporation occurs at a constant rate through the entire interphase. The rate of 14C adenine incorporation into RNA is low during the first half of interphase and high during the last half. The synthesis of DNA, as indicated by tritium-thymidine incorporation, is restricted to the first half of interphase.

The effect of excess vitamin A on the uptake of labelled compounds by embryonic skin in organ culture

1. 1. The object of the experiments was to try to identify by autoradiography, some of the earliest metabolic changes that accompany the mucous metaplasia induced in explants of embryonic chicken skin by excess vitamin A. 2. 2. The incorporation of 35S- l-cystine and methionine, 14C-leucine and tyrosine, 3H-thymidine, 14C-adenine, and 35S-sulphate was studied in explants of skin from the shanks of 13-day embryos, grown in normal and in +A medium for 2–6 days. 3. 3. In both the +A and control explants, all the amino acids were incorporated in the epidermal nuclei as well as in the cytoplasm; this suggests that both nucleus and cytoplasm may be concerned in protein-synthesis, 4. 4. Vitamin A had no significant effect on the uptake of leucine and methionine by the epidermis, but it reduced the incorporation of tyrosine in the superficial layers and greatly diminished that of cystine throughout the epithelium. 5. 5. Vitamin A stimulated the incorporation of adenine and thymidine and probably also the synthesis of DNA in the differentiated (superficial) layers of the epidermis. 6. 6. In the deeper layers of the epidermis the uptake of 35SO 4 was the same in both +A and control explants. In the superficial layers of 2-day cultures, the uptake was very slight in the keratinising cells of the controls, but in the +A explants it was about the same as in the basal cells; after 6 days in culture, uptake remained very scanty in the upper layers of the control epidermis, but was intense in those of the +A skin where it was correlated with mucus-secretion. 7. 7. We suggest that ( a) basal and early differentiated cells in keratinising epithelium have a mechanism for producing sulphated mucopolysaccharides; this mechanism is blocked by keratinisation, but not when keratinisation is stopped by excess vitamin A. ( b) 2 days' treatment with excess vitamin A alters the composition of the proteins synthesized by the epidermis but does not grossly affect the total amount produced. 8. 8. It is not clear whether the reduction in uptake of cystine and/or the increase in that of precursors of DNA should be regarded as the primary effect of excess vitamin A leading to the mucous transformation.

Nucleotide and polynucleotide synthesis in Trypanosoma cruzi. II. In vitro effect of tioguanine and of the aminonucleoside of Stylomycin

The effects of tioguanine and aminonucleoside of Stylomycin on T. cruzi in vitro were studied. The rate of incorporation of C 14 adenine into the acid soluble adenine compounds and mixed nucleic acids purines was used as the test system for the study of the effect of the antagonist. Both compounds were shown to exert a marked inhibitory effect on the rate of adenine incorporation. T. cruzi is equally permeable for Stylomycin and its aminonucleoside moiety. The former compound is known to exert no effect on the synthesis of purine nucleotides by T. cruzi in vitro.

Biochemical studies on vaccinia virus in cultured cells: I. Incorporation of adenine- 8-C14 into normal and infected cells

The incorporation of adenine- 8-C 14 into the nucleic acids of virus-infected cells was studied in the system of vaccinia virus (strain V-MH) growing in monolayers of HeLa cells. All cells were infected and yielded an average of 100 pock-forming units of virus per cell in 30 hours. The tracer was incorporated into both nuclear and cytoplasmic RNA. During the early stages of infection the rate of incorporation of adenine into the microsomal fraction of infected cells was significantly greater than that into the corresponding fraction from normal cells. The maximum was reached at about the time when the first new virus particles appeared; as cellular damage became marked, the rate of incorporation decreased. The effect of certain variables such as the length of the infection period, the duration of exposure to adenine, the multiplicity of infection, and the composition of the medium were studied. No significant increase in either RNA or DNA could be demonstrated. The pattern of the incorporation in relation to the time scale of virus multiplication and the distribution of the label among cell fractions is discussed.

Ribonucleic acid metabolism in u.v.-irradiated Escherichia coli B

The effect of u.v.-irradiation on RNA was studied in cultures of Escherichia coli B during logarithmic growth. The incorporation of adenine was observed in subcellular fractions that can be isolated after subjecting protoplasts to osmotic shock. In the irradiated cultures the incorporation of adenine into RNA was found to occur in all fractions with a few minutes' delay. This incorporation was lower in the faster sedimenting ribonucleoprotein particles. On the other hand it was found to be higher in the supernatant fraction. It seems that the RNA synthesized by this fraction becomes soluble, a fact possibly resulting from the incomplete formation of a ribonucleoprotein.

Biochemical studies on vaccinia virus in cultured cells: II. Localization of adenine- 8-C14 incorporated in the course of infection

Infection with vaccinia virus strain V-MH raises the rate of incorporation of adenine- 8-C 14 into the microsomal fraction of HeLa cells. The increased amount of label incorporated has been shown to be located exclusively in RNA, and almost all of it can be recovered as adenylic acid after alkaline hydrolysis of microsomal RNA; the remainder resides in guanylic acid. Fractionation of the microsomal fraction did not lead to any one subfraction containing all the incorporated label.

ADENINE INCORPORATION AND CELL DIVISION IN SHOOT APICES

SummaryIncorporation of 14C labelled adenine into DNA has been used to investigate the rates of division among cells of shoot meristems. This technique shows that all the cells of a growing apex, including the axial cells of the outermost layers, synthesize DNA. There is no quiescent region such as is found in root meristems. This conclusion is at variance with some of the recent views on the behaviour of shoot meristems.

Early utilization of adenine and formate by mouse ascites tumor cells in vivo

A tracer dose of adenine-8- 14C injected intraperitoneally into mice with Ehrlich-Landschütz (hyperdiploid) ascites tumors was rapidly taken up by the tumor cells (89% after 2 minutes, 98% after 5 minutes). The adenine was equally rapidly incorporated into the nucleotide fraction of the cells, less than 5% of the total cellular activity remaining as free adenine after 2 minutes. A decrease in the radioactivity of the total acid-soluble and total nucleotide fractions occured over the interval of 2–40 minutes after injection, while during this time the total acid-insoluble, RNA and DNA activities increased. Neither barbiturate anesthesia of the host nor X-irradiation with 350 R 2 minutes before injection had any effect on the uptake or incorporation of adenine by the tumor cells when measured 10 minutes after the injection. Intraperitoneally-administered formate- 14C was taken up and utilized by the tumor cells more slowly than was adenine, but over the interval of 10–40 minutes after injection it was incorporated into all fractions investigated. Changes in the specific and total activities of adenine and guanine with time were measured in the various fractions and the metabolic pathways indicated by the above findings considered.

The assimilation of amino acids by bacteria. 26. The incorporation of adenine into the nucleic acid of disrupted staphylococcal cells.

The assimilation of amino acids by bacteria. 26. The incorporation of adenine into the nucleic acid of disrupted staphylococcal cells.

Nucleotide and polynucleotide synthesis in Trypanosoma cruzi. I. Precursors of purine compounds

The in vitro synthesis of acid soluble adenine compounds and nucleic acids purines was studied in T. cruzi. The protozoa can synthesize de novo their purine compounds as measured by the glycine incorporation into the acid soluble adenine nucleotide. However, the rate of this synthesis is very low and seems to be unaffected by azaserine and Stylomycin. At the same time glycine-C 14 is rapidly incorporated into the protein. On the other hand, radioactive adenine is incorporated at very high rate into the acid soluble adenine nucleotides as well as into the nucleic acids purines, probably indicating the preformed purine pathway as the preferential one used by T. cruzi in vitro to synthesize its purine nucleotides. The last process was studied in the presence of some antibiotics and purine inhibitors, with the following results: 1. 1) 6-Mercaptopurine seems to have a slight and brief inhibitory action on the adenine incorporation into both, acid-soluble and insoluble purine compounds and Stylomycin and azaserine possibly have no effect. 2. 2) The synthesis of the nucleic acids purines seems to proceed at equal rates in the presence or absence of d(-)threo-chloramphenicol. However, the specific activity of the acid-soluble adenine compounds is much lower when d(-)threo-chloramphenicol is acting on T. cruzi.

A new factor involved in amino acid incorporation and nucleic aced synthesis

AbstractTable II summarises the present situation concerning the activities of the incorporation factor preparation. If disrupted staphylococcal cells are treated so that the greater part of their nucleic acid is removed, then the incorporation of a single amino acid such as glycine or glutamic acid can be promoted by the IF preparation to the same extent as by nucleic acid. The synthesis of RNA, as measured by the incorporation of adenine into the RNA fraction, requires the presence of a complete mixture of amino acids, the natural purines and pyrimidines, DNA and the IF preparation. The synthesis of protein, as judged by the development of catalase and β‐galactosidase, requires a complete mixture of amino acids, DNA and, in the case of catalase, RNA or in the case of β‐galactosidase, the synthesis of RNA; in neither case does IF have any effect over and above that involved in the nucleic acid or its synthesis. This may mean that the factor is concerned in the synthesis of ribonucleic acid and the role of amino acids in that synthesis rather than in the formation of protein per se.

The effects of 6-mercaptopurine on Lactobacillus casei

The inhibitory action of 6-mercaptopurine has been shown to be manifested by an interference with purine interconversion. The incorporation of adenine and of adenylic acid are affected in different ways by 6-mercaptopurine. These facts have been fitted to a schematic representation of a purine interconversion cycle compatible with the known metabolic behavior of L. casei.

Effect of 20-methylcholanthrene on DNA synthesis in mouse prostates grown in vitro

Ventral prostate glands of C 3H mice were grown in vitro in normal medium and in medium containing 4 μg per ml of 20-methylcholanthrene. The explants were labelled with [8- 14C]-adenine after 4, 7 and 10 days' treatment and fixed 5 or 24 hours later. Autoradiographs of unextracted slides or slides from which the RNA had been removed with ribonuclease or cold perchloric acid were prepared. Untreated sections of controls show incorporation of adenine in both epithelium and fibroblasts. In explants exposed to the carcinogen the distribution of labelled cells in the alveolar epithelium is similar to that in the controls; labelled fibroblasts are still found after 4 days' treatment, but at 7 and 10 days they are unlabelled. Autoradiographs of sections treated with ribonuclease or cold perchloric acid can be assumed to be due to labelled DNA. In controls, epithelium and fibroblasts are labelled; in MC treated explants epithelial cells only are labelled while DNA synthesis by fibroblasts is inhibited after more than 4 days' treatment. Cell counts show that after 4 days' treatment with the carcinogen the percentage of epithelial cells synthesizing DNA is equal to that in controls although the mitotic index is doubled; after 7–10 days the percentage of synthesizing cells increases by 40 per cent in the treated explants, but the mitotic index rises to 3–4 times the control value. It is suggested that some cells in the controls synthesize DNA without proceeding to division and that these cells are forced into division by 20-methylcholanthrene.

Action de la ribonucléase sur la croissance néoplasique V. Aspects métaboliques de l'effet cancérostatique

In the cells of ascites tumours (Landschütz) ribonuclease causes, both in vivo and in vitro, a rapid alteration in the metabolism of ribonucleic acid. The rates of incorporation of adenine and of guanine are modified only slightly or not at all, whereas those of uracil and cytosine are considerably increased (more than 100%). Thus the metabolism of the pyrimidines is greatly accelerated in the presence of RNase. Moreover, the metabolism of the thymine of ADN is disturbed. It also seems that under these, conditions, i.e. during the first stage of the action, the metabolism of the proteins is not modified. Our results indicate that RNase causes the rapid appearance of an abnormal ribonucleic acid and that the carcinostatic action of this enzyme must be sought in the imbalance of the metabolism of the nucleic acids.

Metabolic changes in nucleic acids during the induction of enzymes by oxygen in resting yeast

The formation of catalase and of several other enzymes which are induced by oxygen in a respiratory-deficient mutant of yeast is accompanied by an increased incorporation of labeled adenine and uracil into RNA and DNA. Different RNA fractions isolated by ammonium sulfate fractionation do not show the same relative increase of adenine incorporation during adaptive enzyme formation. The results reported indicate that in resting yeast enzymatic adaptation is associated with changes in some RNA fractions and possibly in DNA.