The DNA content of single cells of Micrococcus radiodurans

1970 ◽  
Vol 16 (11) ◽  
pp. 1136-1137 ◽  
Author(s):  
A. A. Driedger
Keyword(s):  
Cell Wall ◽  
Dna Content ◽  
Deoxyribonucleic Acid ◽  
Single Cells ◽  
Phase Cell ◽  
Logarithmic Phase ◽  
Cell Counts ◽  
Controlled Treatment

Single cells of Micrococcus radiodurans may be liberated from their cell wall by a controlled treatment with lysozyme, thus making accurate cell counts possible. An average logarithmic phase cell contains 1.92 × 10−14 g of deoxyribonucleic acid (DNA).

The mechanism of action of griseofulvin

1968 ◽  
Vol 14 (2) ◽  
pp. 111-118 ◽  
Author(s):  
Floyd M. Huber ◽  
David Gottlieb
Keyword(s):  
Cell Wall ◽  
Botrytis Cinerea ◽  
Aspartic Acid ◽  
Mechanism Of Action ◽  
Dna Content ◽  
Ribonucleic Acid ◽  
Deoxyribonucleic Acid ◽  
Lipid Fraction ◽  
Acid Incorporation ◽  
Total Dna

Griseofulvin had no effect on the respiration of Botrytis cinerea but, nevertheless, inhibited growth and caused abnormal hyphal formations, including stunting, spiraling, thickening of the cell wall, and disorientation of growth. Treated cells had an increase in total deoxyribonucleic acid and phosphorus but not in protein, carbohydrate, lipid, and ribonucleic acid. Griseofulvin-treated cells synthesized DNA from labelled glucose and glycine continuously and for much longer periods than control cells so that their total DNA content was greater than that in untreated cells. However, the antibiotic allowed slightly less incorporation with aspartic acid -U-14C as the precursor than the controls. Griseofulvin caused 25 to 50% increased incorporation of carbon into RNA from glucose and glycine but the increases were not due to a prolongation of the synthetic period, and again aspartic acid incorporation was slightly decreased. Griseofulvin was bound to the particulate parts of the cell and was especially high in the lipid fraction of the cell. The antibiotic was not bound to DNA or to RNA.

Accumulation of DNA in the exopolymeric matrix of activated sludge and bacterial cultures

1996 ◽  
Vol 34 (5-6) ◽  
pp. 233-240 ◽  
Author(s):  
Rikke Palmgren ◽  
Per Halkjær Nielsen
Keyword(s):  
Activated Sludge ◽  
Metal Ions ◽  
Dna Content ◽  
Pure Culture ◽  
Deoxyribonucleic Acid ◽  
Cell Number ◽  
Sludge Flocs ◽  
Bacterial Cultures ◽  
Cell Counts ◽  
Very High

More deoxyribonucleic acid (DNA) was measured than could be accounted for by cell counts in activated sludge flocs, a mixed culture of sludge bacteria, and a pure culture of Pseudomonas putida. This means that estimations of cell number or biomass by measurement and correlation with DNA content will result in an overestimation of the cell number or biomass by up to a factor 10. There could be four reasons for the fact that the DNA was present: There were no specific enzymes present that degrade DNA (DNAses), DNAses were inhibited by humic or humic-like substances, the DNA was protected by coiling with metal ions or the turnover of DNA was very high. For activated sludge it is unlikely that there were no DNAses present but inhibition of DNAses and protection of DNA by metal ions are the most probable reasons why the DNA stays in the systems. The DNA was found in the activated sludge floc exopolymeric matrix whereas DNA from the bacterial cultures was found mainly in the bulk phase (in the slimes).

scholarly journals Anti-Human Immunodeficiency Virus Type 1 Activity, Intracellular Metabolism, and Pharmacokinetic Evaluation of 2′-Deoxy-3′-Oxa-4′-Thiocytidine

1999 ◽  
Vol 43 (8) ◽  
pp. 1835-1844 ◽  
Author(s):  
Jean-Marc de Muys ◽  
Henriette Gourdeau ◽  
Nghe Nguyen-Ba ◽  
Debra L. Taylor ◽  
Parvin S. Ahmed ◽  
...  
Keyword(s):  
Human Immunodeficiency Virus ◽  
Phase Cell ◽  
Logarithmic Phase ◽  
Thymidine Uptake ◽  
Immunodeficiency Virus ◽  
Drug Naïve ◽  
Intracellular Metabolism ◽  
Hiv 1

ABSTRACT The racemic nucleoside analogue 2′-deoxy-3′-oxa-4′-thiocytidine (dOTC) is in clinical development for the treatment of human immunodeficiency virus (HIV) type 1 (HIV-1) infection. dOTC is structurally related to lamivudine (3TC), but the oxygen and sulfur in the furanosyl ring are transposed. Intracellular metabolism studies showed that dOTC is phosphorylated within cells via the deoxycytidine kinase pathway and that approximately 2 to 5% of dOTC is converted into the racemic triphosphate derivatives, which had measurable half-lives (2 to 3 hours) within cells. Both 5′-triphosphate (TP) derivatives of dOTC were more potent than 3TC-TP at inhibiting HIV-1 reverse transcriptase (RT) in vitro. The Ki values for dOTC-TP obtained against human DNA polymerases α, β, and γ were 5,000-, 78-, and 571-fold greater, respectively, than those for HIV RT (28 nM), indicating a good selectivity for the viral enzyme. In culture experiments, dOTC is a potent inhibitor of primary isolates of HIV-1, which were obtained from antiretroviral drug-naive patients as well as from nucleoside therapy-experienced (3TC- and/or zidovudine [AZT]-treated) patients. The mean 50% inhibitory concentration of dOTC for drug-naive isolates was 1.76 μM, rising to only 2.53 and 2.5 μM for viruses resistant to 3TC and viruses resistant to 3TC and AZT, respectively. This minimal change in activity is in contrast to the more dramatic changes observed when 3TC or AZT was evaluated against these same viral isolates. In tissue culture studies, the 50% toxicity levels for dOTC, which were determined by using [3H]thymidine uptake as a measure of logarithmic-phase cell proliferation, was greater than 100 μM for all cell lines tested. In addition, after 14 days of continuous culture, at concentrations up to 10 μM, no measurable toxic effect on HepG2 cells or mitochondrial DNA replication within these cells was observed. When administered orally to rats, dOTC was well absorbed, with a bioavailability of approximately 77%, with a high proportion (approximately 16.5% of the levels in serum) found in the cerebrospinal fluid.

Ribosomal ribonucleic acid cistron homologies among Hyphomicrobium and various other bacteria

1977 ◽  
Vol 23 (4) ◽  
pp. 478-481 ◽  
Author(s):  
Richard L. Moore
Keyword(s):  
Cell Wall ◽  
Ribonucleic Acid ◽  
Deoxyribonucleic Acid ◽  
Gram Positive ◽  
Gram Negative ◽  
Group Iii ◽  
Hybrid Formation ◽  
Group I ◽  
Ribosomal Ribonucleic Acid ◽  
Taxonomic Implications

The extent of hybrid formation between the ribosomal ribonucleic acid (r-RNA) of Hyphomicrobium strain B-522 and deoxyribonucleic acid (DNA) from bacteria of 21 different genera was examined. Three generalized groupings were formed. Group I (72–100%) consisted entirely of other strains of Hyphomicrobium. Representatives of the genera Rhodopseudomonas, Chromatium, Caulobacter, Prosthecomicrobium, Rhodomicrobium, Hyphomonas, and Hyphomicrobium made up group II (49–69%). The remaining Gram-negative, Gram-positive, and cell wall – less bacteria fell into group III (12–40%). The taxonomic implications of these results are discussed.

Analysis of the Crushing Effect about Ultrasound on E. coli and B. subtilis

2012 ◽  
Vol 260-261 ◽  
pp. 1017-1021
Author(s):  
Xin Ying Wang ◽  
Yong Tao Liu ◽  
Min Hui ◽  
Ji Fei Xu
Keyword(s):  
Escherichia Coli ◽  
Cell Wall ◽  
Bacillus Subtilis ◽  
Bacterial Cell ◽  
Logarithmic Phase ◽  
Growth Stages ◽  
Bacterial Cells ◽  
E Coli ◽  
Different Growth Stages ◽  
Main Factor

Escherichia coli and Bacillus subtilis as objects of the study, ultrasonic fragmentation acted on the bacterial cells in different growth stages, results showed that, it’s similar to the crushing effect of ultrasound on E. coli and B. subtilis cells of different growth stages, the highest crushing rate in the logarithmic phase, reached to 95.8% and 94.3% respectively, the crushing rate of adjustment phase is lowest, maintained at around 60%, the crushing rate stability cell was centered, which can be achieved 90%. The structure of the bacterial cell wall didn’t the main factor to decide the ultrasonic fragmentation effect, but different growth periods of bacterial cells did the determinant.

Growth hormone and mammary gland lobule-alveolar development

1961 ◽  
Vol 201 (2) ◽  
pp. 259-263 ◽  
Author(s):  
Richard C. Moon
Keyword(s):  
Growth Hormone ◽  
Mammary Gland ◽  
Dna Content ◽  
Deoxyribonucleic Acid ◽  
Cellular Proliferation ◽  
Estradiol Benzoate ◽  
The Mean ◽  
Alveolar Formation ◽  
Inguinal Glands ◽  
Range Of Values

The effect of growth hormone on mammary gland lobule-alveolar growth in the ovariectomized rat was studied using deoxyribonucleic acid (DNA) of the abdominal-inguinal glands as an index of the degree of cellular proliferation. The administration of 1 mg growth hormone in combination with 2 µg estradiol benzoate for 19 days resulted in alveolar formation and an increase in mammary DNA content above that resulting from injections of either hormone alone. The mean DNA concentration of glands of rats treated with 2 µg estradiol, 6 mg progesterone, 3 µg/100 g l-thyroxine, and 0.5, 1.0, 1.5, and 2.0 mg growth hormone was significantly greater than that of animals receiving only the estradiol, progesterone, and thyroxine. The increase in the mean DNA content was due to a shift in the range of values to a higher plane and did not result from an elevated DNA in only a few animals. It is suggested that the administration of growth hormone during the growth phase of the mammary gland may have a beneficial effect on the subsequent lactation.

scholarly journals Response of Listeria monocytogenes to Disinfection Stress at the Single-Cell and Population Levels as Monitored by Intracellular pH Measurements and Viable-Cell Counts

2009 ◽  
Vol 75 (13) ◽  
pp. 4550-4556 ◽  
Author(s):  
Vicky G. Kastbjerg ◽  
Dennis S. Nielsen ◽  
Nils Arneborg ◽  
Lone Gram
Keyword(s):  
Listeria Monocytogenes ◽  
Single Cell ◽  
Intracellular Ph ◽  
Bacterial Population ◽  
Single Cells ◽  
Viable Cell ◽  
Population Subdivision ◽  
Single Cell Level ◽  
Cell Level ◽  
Cell Counts

ABSTRACT Listeria monocytogenes has a remarkable ability to survive and persist in food production environments. The purpose of the present study was to determine if cells in a population of L. monocytogenes differ in sensitivity to disinfection agents as this could be a factor explaining persistence of the bacterium. In situ analyses of Listeria monocytogenes single cells were performed during exposure to different concentrations of the disinfectant Incimaxx DES to study a possible population subdivision. Bacterial survival was quantified with plate counting and disinfection stress at the single-cell level by measuring intracellular pH (pHi) over time by fluorescence ratio imaging microscopy. pHi values were initially 7 to 7.5 and decreased in both attached and planktonic L. monocytogenes cells during exposure to sublethal and lethal concentrations of Incimaxx DES. The response of the bacterial population was homogenous; hence, subpopulations were not detected. However, pregrowth with NaCl protected the planktonic bacterial cells during disinfection with Incimaxx (0.0015%) since pHi was higher (6 to 6.5) for the bacterial population pregrown with NaCl than for cells grown without NaCl (pHi 5 to 5.5) (P < 0.05). The protective effect of NaCl was reflected by viable-cell counts at a higher concentration of Incimaxx (0.0031%), where the salt-grown population survived better than the population grown without NaCl (P < 0.05). NaCl protected attached cells through drying but not during disinfection. This study indicates that a population of L. monocytogenes cells, whether planktonic or attached, is homogenous with respect to sensitivity to an acidic disinfectant studied on the single-cell level. Hence a major subpopulation more tolerant to disinfectants, and hence more persistent, does not appear to be present.

scholarly journals Rapid cell expansion and cellulose synthesis regulated by plasmodesmata and sugar: insights from the single-celled cotton fibre

2007 ◽  
Vol 34 (1) ◽  
pp. 1 ◽  
Author(s):  
Yong-Ling Ruan
Keyword(s):  
Cell Wall ◽  
Cell Biology ◽  
Secondary Cell Wall ◽  
Higher Plants ◽  
Single Cells ◽  
Critical Role ◽  
Fibre Length ◽  
Cotton Fibre ◽  
Cellulose Synthesis ◽  
Temporary Closure

Higher plants comprise mixtures of some 40 different cell types, and this often complicates the interpretation of data obtained at the tissue level. Studies for a given cell type may provide novel insights into the mechanisms underlying defined cellular and developmental processes. In this regard, the cotton fibre represents an excellent single-cell model to study the control of rapid cell elongation and cellulose synthesis. These single cells, initiated from the ovule epidermis at anthesis, typically elongate to ~3–5 cm in the tetraploid species before they switch to intensive secondary cell wall cellulose synthesis. By maturity, more than 94% of fibre weight is cellulose. To unravel the mechanisms of fibre elongation and cellulose synthesis, two hypotheses have been examined: (a) that sucrose degradation and utilisation mediated by sucrose synthase (Sus) may play roles in fibre development and (b) that symplastic isolation of the fibre cells may be required for their rapid elongation. Reverse genetic and biochemical analyses have revealed the critical role that Sus plays in fibre initiation and early elongation. Late in development, plasma-membrane and cell wall association of Sus protein seems to be involved in rapid cellulose synthesis. Cell biology and gene expression studies showed a temporary closure of fibre plasmodesmata (PD), probably due to the deposition of callose, at the rapid phase of elongation. The duration of the PD closure correlates positively with the final fibre length attained. These data support the view that PD closure may be required for fibres to achieve extended elongation. The branching of PD towards the secondary cell wall stage is postulated to function as a molecule sieve for tight control of macromolecule trafficking into fibres to sustain intensive cellulose synthesis.

HISTOCHEMICAL CHANGES IN THE SHOOT TIP OF CAULIFLOWER DURING FLORAL INDUCTION

1967 ◽  
Vol 45 (7) ◽  
pp. 955-959 ◽  
Author(s):  
Sidki Sadik ◽  
J. L. Ozbun
Keyword(s):  
Shoot Apex ◽  
Dna Content ◽  
Deoxyribonucleic Acid ◽  
Floral Induction ◽  
Fold Increase ◽  
Bromophenol Blue ◽  
Shoot Apices ◽  
Fast Green ◽  
Floral Primordia ◽  
Histochemical Changes

Cauliflower plants were induced to flower after being grown at 42 °F for varying periods of time, depending on the cultivar. Some of the histochemical changes in the shoot apex at the beginning of, during, and after floral induction were studied. During floral induction there is about a 20-fold increase in the volume of nucleoli and about a 3-fold increase in volume of nuclei. Apices of vegetative plants stained with bromophenol blue at pH 2.3, show small and dense nucleoli, dense and granular nuclei, and a small amount of weakly staining cytoplasm. In contrast, cells of apices of induced plants stained with bromophenol blue at pH 2.3, show large and dense nucleoli, large and weakly staining nuclei; however, these cells contain more and denser cytoplasm. Sections of vegetative and induced apices stained with alkaline fast green stained differently from those stained with bromophenol blue. Nucleoli did not stain and cytoplasm stained faintly with fast green while chromosomes stained strongly. Deoxyribonucleic acid (DNA) content of vegetative and induced apices are similar. Shoot apices of vegetative plants contained little or no starch. However, shoot apices of plants grown at 42 °F accumulate large amounts of starch. Floral primordia which develop into functional flowers are glutted with starch, while floral primordia which abort are void of starch.

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