Inhibition Of Deoxyribonucleic Acid Synthesis Research Articles

Rate stimulation of deoxyribonucleic acid synthesis after inhibition.

The degree to which the rate of deoxyribonucleic acid synthesis in thy- cultures of Escherichia coli is stimulated after a period of thymine starvation is shown to be a function of the concentration of thymine present as well as of the culture doubling time. Inhibition of deoxyribonucleic acid synthesis by nalidixic acid yields comparable results. Periods of thymine starvation exceeding one doubling time appear to cause an irreversible inactivation of a fraction of the replication forks in the culture.

Inhibition of an early event in the cell division cycle of Escherichia coli by FL1060, an amidinopenicillanic acid

Analysis of exponential and synchronous cultures of Escherichia coli B/r after the addition of FL1060 indicates a block point for division by this agent some 15 to 20 min before the end of the preceding cell division cycle, a time corresponding to the beginning of the C period of the cell division cycle. Morphological examination of FL1060-treated synchronous cultures of E. coli /r was consistent with inhibition by FL1060 of a very early event in the cell division cycle. This event appears to be essential for normal cell surface elongation in a rod configuration. Temporary treatment of synchronous cultures of E. coli B/r with FL1060 resulted in division delay, the extent of which was a function of the duration of exposure to FL1060. However, even after relatively long times of FL1060 treatment the delayed divisions were still synchronous. Although FL1060 had no direct effect on deoxyribonucleic acid (DNA) synthesis, the synchronous delayed division occuring after temporary treatment with FL1060 were accompanied by a delay in the attainment of resistance of cell division to inhibitors of DNA, ribonucleic acid, and protein synthesis. These results suggest aht an FL1060-sensitive event initiates at the beginning of the C period of the cell division cycle of E. coli and is responsible for normal cell elongation. This cell elongation pathway procedes independently of DNA synthesis, but there is an interaction between this pathway and termination of a round of DNA replication in which a normal rod configuration is necessary to allow a signal for cell division to be generated upon completion of DNA replication.

Location of the Escherichia coli K-12 ruv gene affecting septum formation after inhibition of deoxyribonucleic acid synthesis.

Escherichia coli ruv gene was located at 36.1 min on the chromosome by P1 transduction experiments and the gene order his - supD - uvrC, dar4 - ruv - eda - fadD - pps was proposed. Complementation analysis by an F' factor carrying genes in the his region indicated that ultraviolet light sensitivity genes, ruv and uvrC, consist of different cistrons and wild-type alleles of these genes are dominant over the mutant alleles.

Cyclic adenosine 3′:5′-monophosphate and inhibition of deoxyribonucleic acid synthesis in vitro

Results are presented which suggest that inhibition of tritiated thymidine incorporation into the deoxyribonucleic acid of bone marrow in vitro by high concentrations of cyclic adenosine 3':5'-monophosphate is pharmacological in nature, and thus apparently unrelated to the physiological actions of cAMP.

Temperature-sensitive deoxyribonucleic acid replication in a dnaC mutant of Bacillus subtilis.

A temperature-sensitive mutant of Bacillus subtilis is defective in deoxyribonucleic acid (DNA) synthesis, contains a lesion in the dnaC locus, and is not primarily an initiation mutant. The amount of DNA synthesized by this mutant at temperatures above 40 C decreases with increasing temperature. DNA synthesis resumes within 20 min after the temperature is lowered to 30 C. In the presence of chloramphenical, DNA synthesis begins at a reduced rate after the temperature is lowered to 30 C. Spores germinated at 46 C cannot initiate DNA replication. The capacity for residual DNA synthesis is stable at the restrictive temperature during inhibition of DNA synthesis. When the temperature is lowered to 30 C after a period of incubation at 43 C, DNA synthesis starts at the origin of the chromosome as well as at preexisting growing points. Similar DNA synthesis patterns are found in mutant cells in vivo and after toluene treatment.

Antitumor effects of bis-thiosemicarbazones— inhibition of deoxyribonucleic acid synthesis in vitro

A group of bis-thiosemicarbazones was evaluated for potential antitumor activity, using the L1210 murine leukemia in cell culture. Drug levels required to inhibit DNA synthesis by 50 per cent, under standard conditions, were determined. The most potent of the agents examined had the structure X[CH 2CR 1=NNHCSNHR 2] 2 where X = C or S and R 1 = R 2 = CH 3. Optimal activity was also obtained with R 1 = H and R 2 = CH 3 only when X = S. The most potent derivatives inhibited DNA synthesis by 50 per cent within 10 min at 10 −6 M levels ( id 50). Metal chelates of several compounds tested were extremely potent inhibitors of DNA synthesis ( id 50 = 10 −7 M or less ). Insolubility in water and short duration of action in vivo may limit effectiveness of the bis-thiosemicarbazones.

Replication of the bacteriocinogenic plasmid Clo DF13 in thermosensitive Escherichia coli mutants defective in initiation or elongation of deoxyribonucleic acid replication.

The replication of the bacteriocinogenic plasmid Clo DF13 has been studied in the seven temperature-sensitive Escherichia coli mutants defective in deoxyribonucleic acid (DNA) replication (dnaA-dnaG). Experiments with dna initiation mutants revealed that the replication of the Clo DF13 plasmid depends to a great extent on the host-determined dnaC (dnaD) gene product, but depends slightly on the dnaA gene product. The synthesis of Clo DF13 plasmid DNA also requires the dnaF and dnaG gene products, which are involved in the elongation of chromosomal DNA replication. In contrast, the Clo DF13 plasmid is able to replicate in the dnaB and dnaE elongation mutants at the restrictive temperature. When de novo protein synthesis is inhibited by chloramphenicol in wild-type cells, the Clo DF13 plasmid continues to replicate for at least 12 h, long after chromosomal DNA synthesis has ceased, resulting in an accumulation of Clo DF13 DNA molecules of about 500 copies per cell. After 3 h of chloramphenicol treatment, the Clo DF13 plasmid replicates at a rate approximately five times the rate in the absence of chloramphenicol. Inhibition of protein synthesis by chloramphenicol does not influence the level of Clo DF13 DNA synthesis at the restrictive temperature in the dna mutants, except for the dnaA mutant. Chloramphenicol abolishes the inhibition of Clo DF13 DNA synthesis in the dnaA mutant at the nonpermissive temperature. Under these conditions, Clo DF13 DNA synthesis was slightly stimulated in the first 30 min after the temperature shift, and continued for more than 3 h at an almost uninhibited level.

On the characteristics of inhibition of deoxyribonucleic acid synthesis by 2,2′-anhydro-1-β-D-arabinofuranosylcytosine

Anhydro-ara-C, a cyclic anhydride of cytosine arabinoside, is initially a very weak inhibitor of DNA synthesis in L1210 murine leukemia cells. With increasing incubation times, such inhibition markedly increases. No evidence could be found to indicate uptake of unaltered anhydro-ara-C, although the drug appears to be a weak inhibitor of the uptake of cytosine arabinoside. Anhydro-ara-C is, however, gradually hydrolyzed, apparently by a non enzymatic process, to form cytosine arabinoside in the extracellular space. Rapid uptake of the latter compound then results in progressive inhibition of DNA synthesis.

Preferential Accumulation of Cytoplasmic Protein Species during Inhibition of Deoxyribonucleic Acid Synthesis in Temperature-Sensitive Chinese Hamster Cells in Culture

Preferential Accumulation of Cytoplasmic Protein Species during Inhibition of Deoxyribonucleic Acid Synthesis in Temperature-Sensitive Chinese Hamster Cells in Culture

Effect of Inhibition of Deoxyribonucleic Acid and Protein Synthesis on the Direction of Cell Wall Growth in Streptococcus faecalis

Selective inhibition of protein synthesis in Streptococcus faecalis (ATCC 9790) was accompanied by a rapid and severe inhibition of cell division and a reduction of enlargement of cellular surface area. Continued synthesis of cell wall polymers resulted in rapid thickening of the wall to an extent not seen in exponential-phase populations. Thus, the normal direction of wall growth was changed from a preferential feeding out of new wall surface to that of thickening existing cell surfaces. However, the overall manner in which the wall thickened, from nascent septa toward polar regions, was the same in both exponential-phase and inhibited populations. In contrast, selective inhibition of deoxyribonucleic acid (DNA) synthesis using mitomycin C was accompanied by an increase in cellular surface area and by division of about 80% of the cells in random populations. Little or no wall thickening was observed until the synthesis of macromolecules other than DNA was impaired and further cell division ceased. Concomitant inhibition of both DNA and protein synthesis inhibited cell division but permitted an increase in average cell volume. In such doubly inhibited cells, walls thickened less than in cells inhibited for protein synthesis only. On the basis of the results obtained, a model for cell surface enlargement and cell division is presented. The model proposes that: (i) each wall enlargement site is influenced by an individual chromosome replication cycle; (ii) during chromosome replication peripheral surface enlargement would be favored over thickening (or septation); (iii) a signal associated with chromosome termination would favor thickening (and septation) at the expense of surface enlargement; and (iv) a factor or signal related to protein synthesis would be required for one or more of the near terminal stages of cell division or cell separation, or both.

Cytochemical and Biochemical Studies on Progesterone-induced Maturation in Amphibian Oocytes: 2. DNA synthesis

During the maturation of amphibian oocytes, Feulgen positive bodies originating from the nucleoli (nucleolar organizers, or ‘cores’) appear in the cytoplasm. The possibility that their deoxyribonucleicacid (DNA) might be replicated in the cytoplasm (rDNA) has been studied, following three different lines of approach: effects of inhibitors of DNA synthesis; cyto-photometric analysis of the DNA content of the Feulgen stained cytoplasmic bodies; characterization, in CsCI gradients, of the DNA which is synthesized after injection of 3H-thymidine into Xenopus laevis oocytes. The results can be summarized as follows: (1) None of the inhibitors used(hydroxyurea, 2′-deoxyadenosine(dA), cytosine arabinoside (Ara-C), bromodeoxyuridine, dimethylbenzylrifampicine, ethidium bromide, X-rays) inhibits progesterone-induced maturation in Rana pipiens and X. laevis oocytes. Only dA (10−2M) and Ara-C (10−2M) slowed down or arrested maturation; but this is probably due to the acidity of the drugs rather than to an inhibition of DNA synthesis. Experiments in which the inhibitors were injected into the oocytes show that the appearance of Feulgen-positive bodies in the cytoplasm is not influenced by agents which block DNA synthesis. (2) Quantitative cytophotometric measurements of the DNA content of the Feulgen positive cytoplasmic bodies rule out the possibility of a large rDN A synthesis during maturation. (3) There is a small DNA synthesis during maturation in x. laevis oocytes. However, this synthesis is merely the continuation of the slow DNA synthesis during oogenesis: it is not increased by progesterone-treatment. No radioactive peak is detectable at the density of rDNA. Enucleation experiments and autoradiography observations show that DNA synthesis takes place in the cytoplasm of the oocytes. Experiments on homogenates and characterization of the radioactive DNA strongly suggest that the neo-synthesized DNA is of mitochondrial origin. It is concluded that there is no other DNA synthesis, during maturation, than the continuation of the mitochondrial DNA synthesis which is already taking place during oogenesis, and that DNA synthesis is not required for successful maturation.

Control of deoxyribonucleic acid synthesis in a Bacillus subtilis mutant temperature sensitive for initiation of chromosome replication.

We used a Bacillus subtilis mutant described previously, which is temperature sensitive for initiation of replication. The inhibition of deoxyribonucleic acid synthesis occurring at 45 C was shown to be reversed when the temperature is lowered even in the absence of protein synthesis. If the bacteria are returned to 30 C, after a prior period at 45 C, they are able to initiate the first round of replication in the presence of chloramphenicol, but the initiation of the second round still requires protein synthesis. This paper shows that the proteins necessary to initiate the second round of replication can be present in bacteria long before this round is initiated. In addition, the appearance of these proteins seems to be influenced by the length of the previous 45 C period. Although similar reinitiation kinetics are observed at 30 C after prior 45 C periods of 30 or 65 min, the ability to initiate the second round without further protein synthesis appears much earlier after a longer exposure at 45 C. To explain these results, a hypothesis is presented which assumes that two different proteins are both necessary for initiation. Only one of these proteins could be accumulated at 45 C during the inhibition of deoxyribonucleic acid synthesis. A peculiarity of initiation material in mutant Ts 37 is that it may be active at 45 C if it has been exposed previously at 30 C.

Combined effects of phytohemagglutinin and staphylococcal enterotoxin B on deoxyribonucleic acid synthesis during blast transformation in human lymphocytes.

Three mitogenic agents, phytohemagglutinin (PHA), staphylococcal enterotoxin B (SEB), and concanavalin A (Con A) were tested for their effects on deoxyribonucleic acid (DNA) synthesis in the normal human lymphocyte. When optimal concentrations of PHA and SEB were combined, tritiated thymidine incorporation in lymphocytes derived from several donors was enhanced significantly. In the presence of graded concentrations of one of these mitogens added to fixed optimal concentrations of the other, this enhancement was shown to be additive. By contrast, when PHA or SEB were combined with Con A, the resulting thymidine incorporation was slightly lower than for either mitogen alone. An inhibition of further thymidine incorporation when puromycin was added to lymphocytes incubated with PHA and SEB suggested that the additive effect of these mitogens was due to increased enzyme synthesis. To define potential differences in mechanisms of action underlying the additive effect of SEB and PHA, the relative contribution of the de novo and salvage pathways for pyrimidine biosynthesis was tested with cytidine, a specific salvage pathway inhibitor. Cytidine (10(-3) M) inhibited synthesis through the salvage pathway, but did not significantly alter induction of carbamyl phosphate synthetase II, the rate-limiting enzyme for the de novo pathway. An inhibition of DNA synthesis by millimolar cytidine concentrations in lymphocytes incubated with PHA or SEB, singly or in combination, suggested that pyrimidines for the observed enhancement of DNA synthesis were derived largely via the salvage pathway.

The effect of inhibition of deoxyribonucleic acid synthesis on histone phosphorylation.

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTEffect of inhibition of deoxyribonucleic acid synthesis on histone phosphorylationRod Balhorn, Nongnuj Tanphaichitr, Roger Chalkley, and D. K. GrannerCite this: Biochemistry 1973, 12, 25, 5146–5150Publication Date (Print):December 1, 1973Publication History Published online1 May 2002Published inissue 1 December 1973https://doi.org/10.1021/bi00749a019RIGHTS & PERMISSIONSArticle Views29Altmetric-Citations23LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (1 MB) Get e-Alerts Get e-Alerts

Inhibition of deoxyribonucleic acid synthesis and bud formation by nalidixic acid in Hyphomicrobium neptunium.

The relationship between chromosome replication and morphogenesis in the budding bacterium Hyphomicrobium neptunium has been investigated. Nalidixic acid was found to completely inhibit deoxyribonucleic acid synthesis, but not ribonucleic acid synthesis. The antibiotic was bacteriostatic to the organism for the initial 5 h of exposure; thereafter it was bacteriocidal. Observation of inhibited cultures revealed cells that had produced abnormally long stalks, but no buds. These results indicate that bud formation is coupled to chromosome replication in H. neptunium. They do not exclude the possibilities that cross wall formation and bud separation may also be coupled to chromosome replication.

Coupling between chromosome completion and cell division in Escherichia coli.

The relationship between termination of chromosome replication and cell division was investigated in Escherichia coli B/r. Synchronous cultures of E. coli B/r growing in glucose minimal medium or subjected to a nutritional shift-up were exposed to chloramphenicol, rifampin, mitomycin C, or nalidixic acid, and the ability of cells to divide in the presence of the inhibitors was measured. It was found that cell division became resistant to inhibitors of ribonucleic acid (RNA) and deoxyribonucleic acid (DNA) synthesis at approximately the same stage in the division cycle in all situations investigated. When the synchronous glucose-grown cultures were temporarily exposed to chloramphenicol early in the division cycle and then exposed to mitomycin C or nalidixic acid immediately after removal of chloramphenicol, the cells did not divide. In contrast, when DNA synthesis was inhibited by thymine starvation immediately after temporary exposure to chloramphenicol, cells divided. The results suggest that DNA chain elongation is completed in some cells in the absence of protein synthesis, but that additional steps involving specific RNA or protein synthesis, or both, may be required for processing the chromosomal structures to the form which is necessary for division. This processing, which normally occurs concurrent with DNA synthesis and is prevented by inhibitors of DNA synthesis, may trigger division. Alternatively, in the absence of protein synthesis, all aspects of chromosome formation may be completed, but final transcriptional events which are essential for division cannot take place until the complete synthesis of a critical amount of specific proteins.

Analysis of cell division in rapidly growing synchronous cultures of Escherichia coli recovering from an inhibition of deoxyribonucleic acid synthesis

Kinetics of cell division in cultures of Escherichia coli grown in casamino acids – glucose and recovering from short pulses of inhibition of DNA synthesis by nalidixic acid clearly demonstrates that preexisting cycles of chromosome replication continue to their ends.

Studies on the developmental cycle of Chlamydia trachomatis: selective inhibition by hydroxyurea.

Hydroxyurea, a potent inhibitor of deoxyribonucleic acid synthesis, inhibits the development of trachoma agent when applied at a concentration of 5 x 10(-2) M. At a lower concentration, 5 x 10(-4) M, hydroxyurea permits the development of the trachoma inclusion bodies and initial bodies, but arrests the formation of elementary bodies, the infectious entity of the agent. The inhibitory effect of 5 x 10(-4) M hydroxyurea is reversible and can be used to synchronize the development of the agent. The synthesis of deoxyribonucleic acid, ribonucleic acid, and proteins takes place in the initial bodies after the removal of the inhibitor.

Regulation of intracellular proteolysis in Escherichia coli.

Individual nitrogenous metabolites have been examined as regulating agents for the breakdown of intracellular proteins in Escherichia coli. Generally, NH(4) (+) is the most effective regulator. Its depletion progressively increases the basal proteolytic rate to maximum in most strains when the doubling time is increased to 2 h. In E. coli 9723, the rate is further increased at longer doubling times. Amino acids have individual effects on intracellular proteolysis. The basal rate in amino acid-requiring auxotrophs of E. coli 9723 is stimulated weakly by starvation for histidine, tryptophan, or tyrosine, moderately by four other amino acid depletions, and more strongly by eight others. The degree of stimulation roughly correlates with the frequency of the amino acid in the cell proteins. Amino acid analogues that incorporate extensively into protein generally slightly inhibit intracellular proteolysis, except for selenomethionine, which is slightly stimulatory. Metabolic inhibitors were studied at graded concentrations. Chloramphenicol inhibits the basal level of intracellular proteolysis when protein synthesis is slightly or moderately inhibited, and stimulates proteolysis slightly at higher levels. Graded inhibition of ribonucleic acid synthesis with rifampin progressively stimulates intracellular proteolysis. Uracil depletion is also stimulatory. Inhibition of deoxyribonucleic acid synthesis with mitomycin C or by thymine starvation slightly inhibits intracellular proteolysis. Intracellular proteolysis is postulated to be regulated primarily by active ribosomal function. At 43 to 45 C, intracellular proteolysis becomes maximally induced and unresponsive to normal regulatory control by metabolites. Most regulation is directed towards the breakdown of the more stable cell proteins. Total proteolysis in all cell proteins is no more than doubled by the most effective conditions of starvation.

Physiology of Escherichia coli K-12 during conjugation: altered recipient cell functions associated with lethal zygosis.

The number of viable F(-) cells decreases when Escherichia coli recipient cells are mixed with an excess of Hfr cells. Evidence is presented showing that lethal zygosis was accompanied by changes in the physiology of the recipient cells, including (i) inhibition of deoxyribonucleic acid synthesis, (ii) inhibition of beta-galactosidase induction, (iii) altered transport and accumulation of galactosides, and (iv) leakage of beta-galactosidase into the supernatant fluid. The results are discussed in terms of possible conjugation-associated changes that, at high Hfr to F(-) ratios, lead to lethal zygosis.