Effect of uridine on the incorporation of thymine and thymidine in Escherichia coli

1973 ◽  
Vol 19 (4) ◽  
pp. 485-490 ◽  
Author(s):  
R. M. Behki ◽  
S. M. Lesley
Keyword(s):  
Escherichia Coli ◽  
Dna Synthesis ◽  
Cell Cultures ◽  
Inhibitory Effect ◽  
High Rate ◽  
Simple Method ◽  
Initial Concentration ◽  
Intact Molecule

Uridine inhibits the incorporation of thymine in Escherichia coli 15T− cells but the duration of this inhibition is dependent upon the initial concentration of uridine and its rate of degradation. Uridine is rapidly degraded to uracil and the completion of this degradation coincides with the release of the inhibitory effect. However, uridine, by preventing the phosphorolysis of thymidine, allows the continued incorporation of the intact molecule at the initial high rate for as long as the concentration of undegraded uridine remains above a certain level. In resuspended 15T− cells, this rate is the same, irrespective of the presence or absence of uridine. The results presented here provide a simple method of controlling DNA synthesis, as represented by thymine incorporation, without the addition of inhibitors or other manipulations of the cell cultures.

scholarly journals DNA synthesis by ovine mammary alveolar epithelial cells: effects of heparin, epidermal growth factor-related peptides and interaction with stage of pregnancy

1998 ◽  
Vol 156 (2) ◽  
pp. 283-290 ◽  
Author(s):  
IA Forsyth ◽  
JA Taylor ◽  
CD Moorby
Keyword(s):  
Growth Factor ◽  
Epidermal Growth Factor ◽  
Epithelial Cells ◽  
Dna Synthesis ◽  
Cell Cultures ◽  
Inhibitory Effect ◽  
Alveolar Epithelial Cells ◽  
Alveolar Epithelial ◽  
Pregnant Sheep ◽  
Epidermal Growth

Amphiregulin is a heparin-binding member of the epidermal growth factor (EGF) family, which we have recently shown to be expressed in sheep mammary gland. Uniquely among known EGF-like growth factors, its mitogenic activity is inhibited by soluble heparin, but heparin-like molecules on the cell surface and/or in extracellular matrix appear to be necessary for amphiregulin to exert its biological effect. In primary cultures of sheep mammary alveolar epithelial cells, heparin (1-20 mg/l) inhibited DNA synthesis in a dose-dependent manner. The extent of the inhibition was influenced by physiological state, being greater (P < 0.05) in mammary cell cultures derived from 5- to 10-week pregnant sheep (63.1 +/- 8.2%, mean +/- S.E.M., n = 8) than in cultures derived from sheep which were non-pregnant (35.8 +/- 8.3% inhibition, n = 6) or late, 20-week, pregnant (39.8 +/- 5.6%, n = 6). Both EGF and transforming growth factor-alpha (TGF-alpha) significantly (P < 0.001) increased DNA synthesis in the presence of heparin. The effect of TGF-alpha was dose-related, wholly reversing the inhibitory effect of heparin in cell cultures from non-pregnant and 20-week pregnant sheep. DNA synthesis was stimulated by amphiregulin and TGF-alpha increased the maximum response. The heparin antagonist, hexadimethrine, inhibited DNA synthesis, but, in the presence of amphiregulin, approximately equivalent concentrations of heparin overcame this inhibitory effect. In the presence of heparin, TGF-alpha showed synergistic interactions with insulin or IGF-I. The results indicate interactive effects of EGF and IGF growth factor families in sheep mammary growth.

scholarly journals Inhibition of DNA synthesis in SV3T3 cultures by isolated 3T3 plasma membranes.

1983 ◽  
Vol 97 (1) ◽  
pp. 276-279 ◽  
Author(s):  
S W Peterson ◽  
V Lerch
Keyword(s):  
Plasma Membrane ◽  
Dna Synthesis ◽  
Cell Cultures ◽  
Plasma Membranes ◽  
Inhibitory Effect ◽  
Density Dependent ◽  
Inhibition Of Growth ◽  
Dependent Inhibition ◽  
Membrane Components ◽  
Inhibition Of Dna Synthesis

3T3 plasma membranes were added to subconfluent cultures of SV3T3 cells in the presence of fusogens. If this protocol results in the introduction into the SV3T3 cell membrane of 3T3 plasma membrane components responsible for density-dependent inhibition of growth, then the SV3T3 cell cultures would be expected to show decreased rates of DNA synthesis as they approach confluence. Results of these experiments indicate that rates of DNA synthesis in SV3T3 cultures so treated were as much as 63% less than in untreated controls. This effect could not be attributed to the fusogens or to the 3T3 plasma membranes alone. This growth-inhibitory effect is specific for 3T3 membranes and is not observed when SV3T3 plasma membranes are fused with SV3T3 cell cultures. These data support the hypothesis that one aspect of the loss of density-dependent inhibition of growth in SV3T3 cells is a deletion or alteration in plasma membrane components and, further, that density-dependent inhibition of growth can be in part restored to SV3T3 cell cultures by fusing the cells with 3T3 plasma membranes.

Rotary Beveling for In Situ Thin-Section Microscopy of Cell Cultures

1981 ◽  
Vol 39 ◽  
pp. 550-551
Author(s):  
Dean A. Handley ◽  
Jack T. Alexander ◽  
Shu Chien
Keyword(s):  
Cell Growth ◽  
Cell Cultures ◽  
Molecular Interactions ◽  
Convenient Method ◽  
Petri Dish ◽  
Simple Method ◽  
Thin Section Microscopy ◽  
Thin Sectioning ◽  
Organic Fluids

In situ preparation of cell cultures for ultrastructural investigations is a convenient method by which fixation, dehydration and embedment are carried out in the culture petri dish. The in situ method offers the advantage of preserving the native orientation of cell-cell interactions, junctional regions and overlapping configurations. In order to section after embedment, the petri dish is usually separated from the polymerized resin by either differential cryo-contraction or solvation in organic fluids. The remaining resin block must be re-embedded before sectioning. Although removal of the petri dish may not disrupt the native cellular geometry, it does sacrifice what is now recognized as an important characteristic of cell growth: cell-substratum molecular interactions. To preserve the topographic cell-substratum relationship, we developed a simple method of tapered rotary beveling to reduce the petri dish thickness to a dimension suitable for direct thin sectioning.

Finite Element Model to Predict the Bioconversion Rate of Glucose to Fructose using Escherichia coli K12 for Sugar Production from Date

2015 ◽  
Vol 11 (1) ◽  
pp. 105-113 ◽  
Author(s):  
Maher Trigui ◽  
Karim Gabsi ◽  
Walid Zneti ◽  
Suzelle Barrington ◽  
Ahmed Noureddine Helal
Keyword(s):  
Escherichia Coli ◽  
Induction Time ◽  
Volume Fraction ◽  
Element Model ◽  
Initial Concentration ◽  
Computational Fluids Dynamics ◽  
Date Syrup ◽  
Computational Fluids ◽  
Two Phases ◽  
Inoculum Volume

Abstract In this study, Bioconversion process of glucose to fructose from date syrup using Escherichia coli K12 is modeled using a commercial computational fluids dynamics (CFD) code fluent FLUENT 6.3.23 [8] which we implemented a user-defined functions (UDF) to simulate the interrelationships at play between various phases. A two phases CFD model was developed using an Eulerian – Eulerian approach to calculate the fructose volume fraction produced during time. The bioconversion process was studied as function of three initial concentration of glucose (0.14, 0.242 and 0.463gL–1), three induction time (60, 120 and 180 mn) and three inoculum volume (100, 120 and 150mL). The numerical results are compared with experimental data for bioconversion rate and show good agreement (R2= 0.894). The optimal condition of diffusion was obtained by applying an initial concentration of glucose less than 0.2gL–1 and induction time great than 100 minutes.

scholarly journals Growth of Nosema cuniculi in established cell lines

1975 ◽  
Vol 9 (1) ◽  
pp. 61-68 ◽  
Author(s):  
T. Waller
Keyword(s):  
Cell Lines ◽  
Cell Cultures ◽  
Growth Patterns ◽  
Rabbit Kidney ◽  
Kidney Cells ◽  
Scale Production ◽  
Simple Method ◽  
Established Cell Lines ◽  
Established Cell ◽  
Canine Kidney

Growth patterns of Nosema cuniculi ( Encephalitozoon cuniculi) in cell cultures of bovine kidney, canine kidney, feline lung, and rabbit kidney were studied. All cell cultures used were easy to manage and the last 3 are commercially-available established cell lines. The dog kidney cells were the most suitable for large-scale production of Nosema. When grown in plastic flasks with a bottom area of 75 cm2, the weekly yield from Nosema-infected canine kidney cells during the 10th to 17th week after inoculation was between 4·1 x 107 and 9·9 x 107 spores per flask. An equilibrium was obtained between the Nosema infection and the kidney cells during this time. A simple method for estimating the numbel of harvested spores is also described.

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