scholarly journals MEMBRANES OF ANIMAL CELLS

1968 ◽  
Vol 37 (3) ◽  
pp. 729-746 ◽  
Author(s):  
L. Warren ◽  
M. C. Glick
Keyword(s):  
Culture Medium ◽  
Surface Membrane ◽  
Particulate Material ◽  
Metabolic Inhibitors ◽  
Plateau Phase ◽  
Animal Cells ◽  
Growing Cell ◽  
Specific Activities ◽  
Cell Fractions ◽  
High Level

Turnover studies of the surface membrane and of cell particulate matter of L cells in tissue culture in logarithmic and plateau phase of growth have been made. The rate of incorporation of isotope into these fractions and the rate of fall of specific activities of labeled L-cell fractions have been observed. The following interpretation of the data appears most likely although other interpretations are possible. Growing and nongrowing cells synthesize approximately similar amounts of surface membrane and particulate material. In the growing cell the material is incorporated with net increases in substance. There is relatively little turnover. In the nongrowing cell newly synthesized material is incorporated, but a corresponding amount of material is eliminated so that there is turnover without net increase of substance. Our results suggest that there is no gross differential turnover between the protein, lipid, and carbohydrate of the surface membrane under the conditions of our experiments. Metabolic inhibitors or omission of amino acids in the culture medium lead to a decrease in synthesis of surface membrane and cell particulates and cause an equivalent decrease in the rate of degradation of surface membrane and of particulates; therefore the synthetic and degradative aspects of turnover appear to be coupled. As cultures of nongrowing cells in suspension or on a glass surface age, their synthetic and turnover capacities diminish. Our results suggest that the cell may exist in a nongrowing state with a level of synthesis similar to that of a growing cell. It can exist in this state with a high level of turnover.

Effect of Some Metabolic Inhibitors on Vinblastine-Induced Ribosomal-Granular Material Complexes

1971 ◽  
Vol 29 ◽  
pp. 548-549
Author(s):  
Awtar Krishan ◽  
Dora Hsu
Keyword(s):  
Granular Material ◽  
Rna Synthesis ◽  
Culture Medium ◽  
Actinomycin D ◽  
Metabolic Inhibitors ◽  
Protein And Rna Synthesis ◽  
Apparent Reduction ◽  
Plant Alkaloids ◽  
In Cells

Cells exposed to antitumor plant alkaloids, vinblastine and vincristine sulfate have large proteinacious crystals and complexes of ribosomes, helical polyribosomes and electron-dense granular material (ribosomal complexes) in their cytoplasm, Binding of H3-colchicine by the in vivo crystals shows that they contain microtubular proteins. Association of ribosomal complexes with the crystals suggests that these structures may be interrelated.In the present study cultured human leukemic lymphoblasts (CCRF-CEM), were incubated with protein and RNA-synthesis inhibitors, p. fluorophenylalanine, puromycin, cycloheximide or actinomycin-D before the addition of crystal-inducing doses of vinblastine to the culture medium. None of these compounds could completely prevent the formation of the ribosomal complexes or the crystals. However, in cells pre-incubated with puromycin, cycloheximide, or actinomycin-D, a reduction in the number and size of the ribosomal complexes was seen. Large helical polyribosomes were absent in the ribosomal complexes of cells treated with puromycin, while in cells exposed to cycloheximide, there was an apparent reduction in the number of ribosomes associated with the ribosomal complexes (Fig. 2).

The Calorimetric-respirometric Ratio: Its Potential as a Cytotoxicity Test

1994 ◽  
Vol 22 (5) ◽  
pp. 364-376
Author(s):  
Richard B. Kemp ◽  
Catherine Stephansen ◽  
Sajid Mohamed ◽  
R.W. John Meredith
Keyword(s):  
Heat Flux ◽  
Salt Solution ◽  
Krebs Cycle ◽  
Cytotoxicity Test ◽  
Antimycin A ◽  
Rich Medium ◽  
Animal Cells ◽  
Normal Input ◽  
High Level ◽  
L929 Mouse

The ratio between heat flux and oxygen flux, the calorimetric ratio, is an enthalpy budget device used to identify anaerobic pathways in the presence of respiration. Ratios that are more exothermic (i.e. more negative) than the average for catabolic substrates (-450kJ mol O2 ± 5%; Thornton's rule), are usual for cells established in culture, including suspension-adapted LS-L929 mouse fibroblasts. A common reason for this is a high level of glycolysis, to produce lactate, simultaneously with aerobic pathways. To test the idea that the calorimetric-respirometric (CR) ratio is a revealing cytotoxic endpoint, LS cells grown in serum-rich medium were insulted with known metabolic poisons. Malonate, 2,4-dinitrophenol (2,4-DNP) and a mixture of antimycin A and rotenone increased the CR ratio to degrees largely explained by greater lactate flux, the CR700 values being 22μM malonate, 56μM 2,4-DNP and, for the mixture, 2μM antimycin A and 5μM rotenone. Higher concentrations of 2,4-DNP gave an “exothermic gap” for which there was no explained pathway. Iodoacetate decreased the CR ratio while inhibiting glycolysis, a result which can be explained by the hypothesis that substrates available in the serum were degraded by mitochondrial pathways and thereby substituted for the normal input from the Krebs cycle, which had been arrested by pyruvate starvation. In a balanced salt solution containing only 5.5mM glucose, the metabolic rate slowed and the CR ratio was more exothermic (CR700 = 6μM), giving a “gap” for which there was no explanation. Ten MEIC chemicals gave CR700 endpoints which closely corresponded to the order of toxicity for a battery of tests using animal cells. The CR method thus provides a good basis for investigating the mechanisms by which chemicals have toxic effects on cells.

scholarly journals RamB, a Novel Transcriptional Regulator of Genes Involved in Acetate Metabolism of Corynebacterium glutamicum

2004 ◽  
Vol 186 (9) ◽  
pp. 2798-2809 ◽  
Author(s):  
Robert Gerstmeir ◽  
Annette Cramer ◽  
Petra Dangel ◽  
Steffen Schaffer ◽  
Bernhard J. Eikmanns
Keyword(s):  
Corynebacterium Glutamicum ◽  
Isocitrate Lyase ◽  
Transcriptional Regulator ◽  
Regulatory Elements ◽  
Malate Synthase ◽  
Acetate Kinase ◽  
Acetate Metabolism ◽  
Peptide Mass ◽  
Specific Activities ◽  
High Level

ABSTRACT The adaptation of Corynebacterium glutamicum to acetate as a carbon and energy source involves transcriptional regulation of the pta-ack operon coding for the acetate-activating enzymes phosphotransacetylase and acetate kinase and of the aceA and aceB genes coding for the glyoxylate cycle enzymes isocitrate lyase and malate synthase, respectively. Deletion and mutation analysis of the respective promoter regions led to the identification of highly conserved 13-bp motifs (AA/GAACTTTGCAAA) as cis-regulatory elements for expression of the pta-ack operon and the aceA and aceB genes. By use of DNA affinity chromatography, a 53-kDa protein specifically binding to the promoter/operator region of the pta-ack operon was purified. Mass spectrometry and peptide mass fingerprinting identified the protein as a putative transcriptional regulator (which was designated RamB). Purified His-tagged RamB protein was shown to bind specifically to both the pta-ack and the aceA/aceB promoter/operator regions. Directed deletion of the ramB gene in the genome of C. glutamicum resulted in mutant strain RG1. Whereas the wild type of C. glutamicum showed high-level specific activities of acetate kinase, phosphotransacetylase, isocitrate lyase, and malate synthase when grown on acetate and low-level specific activities when grown on glucose as sole carbon and energy sources, mutant RG1 showed high-level specific activities with all four enzymes irrespective of the substrate. Comparative transcriptional cat fusion experiments revealed that this deregulation takes place at the level of transcription. The results indicate that RamB is a negative transcriptional regulator of genes involved in acetate metabolism of C. glutamicum.

Numerical Simulation and Experimental Study on Light Scattering by Biological Cells with Discrete Dipole Approximation

2013 ◽  
Vol 760-762 ◽  
pp. 105-109 ◽  
Author(s):  
Jian Bin Liu ◽  
Hai Li ◽  
Ying Xin Zeng ◽  
Jia Wen Weng ◽  
Chu Ping Yang
Keyword(s):  
Cell Culture ◽  
Light Scattering ◽  
Culture Medium ◽  
Dipole Approximation ◽  
Spherical Particles ◽  
Biological Cells ◽  
Cell Culture Medium ◽  
Animal Cells ◽  
Experimental Apparatus ◽  
Liquid Suspensions

An experimental apparatus for the analysis of biological cells light scattering in liquid suspensions has been presented. Characterization is based on the scattering of a monochromatic laser beam by particles [which can be inorganic, organic, or biological (such as animal cells and bacteria)] and on the strong relation between the light-scattering pattern and the morphology and refractive index of the particles. In order to study light scattering in biological cells close to the actual situation, we focus on non-spherical particles in the cell-culture medium. Finally, we demonstrate the light scattering results of bovine kidney cells suspended in the cell-culture medium, and compares then with the simulated results.

scholarly journals Evaluation of antibiotics as a methodological procedure to inhibit free-living and biofilm bacteria in marine zooplankton culture

2016 ◽  
Vol 88 (suppl 1) ◽  
pp. 733-746 ◽  
Author(s):  
Vanessa O. Agostini ◽  
Alexandre J. Macedo ◽  
Erik Muxagata
Keyword(s):  
Half Life ◽  
Culture Medium ◽  
Metabolic Inhibitors ◽  
Penicillin G ◽  
Streptomycin Sulphate ◽  
Free Living ◽  
Marine Zooplankton ◽  
Scientific Experiments ◽  
Biofilm Bacteria

There is a problem with keeping culture medium completely or partially free from bacteria. The use of prokaryotic metabolic inhibitors, such as antibiotics, is suggested as an alternative solution, although such substances should not harm non-target organisms. Thus, the aim of this study was to assess the effectiveness of antibiotic treatments in inhibiting free-living and biofilm bacteria and their half-life in artificial marine environment using the copepod Acartia tonsa as bioindicador of non-harmful antibiotic combinations. Regarding to results, the application of 0.025 g L-1 penicillin G potassium + 0.08 g L-1 streptomycin sulphate + 0.04 g L-1 neomycin sulphate showed great potential for use in marine cultures and scientific experiments without lethal effects to non-target organisms. The effect of this combination starts within the first six hours of exposure and reduces up to 93 % the bacterial density, but the half-life is short, requiring replacement. No adverse changes in water quality were observed within 168 hours of exposure. As a conclusion, we can infer that this treatment was an effective procedure for zooplankton cultures and scientific experiments with the aim of measuring the role of free-living and biofilm in the marine community.

scholarly journals In vitro answer of Bulgarian pepper (Capsicum annuum L.)

Genetika ◽  
2006 ◽  
Vol 38 (2) ◽  
pp. 129-136
Author(s):  
Velichka Rodeva ◽  
Stanislava Grozeva ◽  
Velichka Todorova
Keyword(s):  
Culture Medium ◽  
Culture Media ◽  
Casein Hydrolysate ◽  
Basal Medium ◽  
Regeneration Ability ◽  
Stem Explants ◽  
Media Composition ◽  
Breeding Lines ◽  
High Level

Callusogenesis and regeneration ability of cotyledon and hypocotyl explants from three Bulgarian pepper varieties in MS basal medium supplemented with l-3mg/l BAP. l.0mg/1 IAA and 0.5mg/l GA3 was studied. In the different variants of culture medium was registered high level of callusogenesis and organogenesis in both type of explants from the all varieties. The highest percentage of plant-regenerants is established in cotyledon explants (from 3.3 to 18.3) in variant 3 of the culture medium containing 3mg/l BA. In the process of micropropagation by stem explants of the same studied pepper varieties the addition of the vitamins C. B12. Casein hydrolysate and Ferulic acid had a stimulation effect on the plant growth in height and rooting. In result of anther cultivation from three pepper varieties and four breeding lines the highest percentage of embryo structure formation was registered in varieties Albena and Strjama (12.0 and 13.8 respectively). The Bulgarian peppers are recalcitrant and their in vitro answer is different depending from the explants type, genotype and the culture media composition.

scholarly journals Evidence That Runt Acts as a Counter-Repressor of Groucho During Drosophila melanogaster Primary Sex Determination

2020 ◽  
Vol 10 (7) ◽  
pp. 2487-2496
Author(s):  
Sharvani Mahadeveraju ◽  
Young-Ho Jung ◽  
James W. Erickson
Keyword(s):  
Drosophila Melanogaster ◽  
Sex Determination ◽  
Transcriptional Repression ◽  
Biological Effects ◽  
Regulatory Gene ◽  
Animal Cells ◽  
Interaction Domain ◽  
Link Type ◽  
High Level ◽  
Runx Proteins

Runx proteins are bifunctional transcription factors that both repress and activate transcription in animal cells. Typically, Runx proteins work in concert with other transcriptional regulators, including co-activators and co-repressors to mediate their biological effects. In Drosophila melanogaster the archetypal Runx protein, Runt, functions in numerous processes including segmentation, neurogenesis and sex determination. During primary sex determination Runt acts as one of four X-linked signal element (XSE) proteins that direct female-specific activation of the establishment promoter (Pe) of the master regulatory gene Sex-lethal (Sxl). Successful activation of SxlPe requires that the XSE proteins overcome the repressive effects of maternally deposited Groucho (Gro), a potent co-repressor of the Gro/TLE family. Runx proteins, including Runt, contain a C-terminal peptide, VWRPY, known to bind to Gro/TLE proteins to mediate transcriptional repression. We show that Runt’s VWRPY co-repressor-interaction domain is needed for Runt to activate SxlPe. Deletion of the Gro-interaction domain eliminates Runt-ability to activate SxlPe, whereas replacement with a higher affinity, VWRPW, sequence promotes Runt-mediated transcription. This suggests that Runt may activate SxlPe by antagonizing Gro function, a conclusion consistent with earlier findings that Runt is needed for Sxl expression only in embryonic regions with high Gro activity. Surprisingly we found that Runt is not required for the initial activation of SxlPe. Instead, Runt is needed to keep SxlPe active during the subsequent period of high-level Sxl transcription suggesting that Runt helps amplify the difference between female and male XSE signals by counter-repressing Gro in female, but not in male, embryos.

scholarly journals Role of Four Calcium Transport Proteins, Encoded bynca-1,nca-2,nca-3, andcax, in Maintaining Intracellular Calcium Levels in Neurospora crassa

2011 ◽  
Vol 10 (5) ◽  
pp. 654-661 ◽  
Author(s):  
Barry J. Bowman ◽  
Stephen Abreu ◽  
Emilio Margolles-Clark ◽  
Marija Draskovic ◽  
Emma Jean Bowman
Keyword(s):  
Neurospora Crassa ◽  
Calcium Transport ◽  
High Speed ◽  
Transport Proteins ◽  
Cell Fractionation ◽  
Animal Cells ◽  
Normal Medium ◽  
Content Type ◽  
Cell Fractions

ABSTRACTWe have examined the distribution of calcium inNeurospora crassaand investigated the role of four predicted calcium transport proteins. The results of cell fractionation experiments showed 4% of cellular calcium in mitochondria, approximately 11% in a dense vacuolar fraction, 40% in an insoluble form that copurifies with microsomes, and 40% in a high-speed supernatant, presumably from large vacuoles that had broken. Strains lacking NCA-1, a SERCA-type Ca2+-ATPase, or NCA-3, a PMC-type Ca2+-ATPase, had no obvious defects in growth or distribution of calcium. A strain lacking NCA-2, which is also a PMC-type Ca2+-ATPase, grew slowly in normal medium and was unable to grow in high concentrations of calcium tolerated by the wild type. Furthermore, when grown in normal concentrations of calcium (0.68 mM), this strain accumulated 4- to 10-fold more calcium than other strains, elevated in all cell fractions. The data suggest that NCA-2 functions in the plasma membrane to pump calcium out of the cell. In this way, it resembles the PMC-type enzymes of animal cells, not the Pmc1p enzyme inSaccharomyces cerevisiaethat resides in the vacuole. Strains lacking thecaxgene, which encodes a Ca2+/H+exchange protein in vacuolar membranes, accumulate very little calcium in the dense vacuolar fraction but have normal levels of calcium in other fractions. Thecaxknockout strain has no other observable phenotypes. These data suggest that “the vacuole” is heterogeneous and that the dense vacuolar fraction contains an organelle that is dependent upon the CAX transporter for accumulation of calcium, while other components of the vacuolar system have multiple calcium transporters.

scholarly journals Stimulierung von Kulturen embryonaler Rattenzellen durch eine Proteinfraktion aus fötalem Kälberserum / Stimulation of Embryonic Rat Cells in Culture by a Protein Fraction Isolated from Fetal Calf Serum

1971 ◽  
Vol 26 (10) ◽  
pp. 1045-1048 ◽  
Author(s):  
Dieter F. Hülser ◽  
Werner Frank
Keyword(s):  
Cell Cycle ◽  
Culture Medium ◽  
Fetal Calf Serum ◽  
Surface Membrane ◽  
Calf Serum ◽  
Serum Free Medium ◽  
Free Medium ◽  
Serum Free ◽  
Membrane Potential Difference ◽  
Stimulation Of

Normal embryonic rat cells incubated in serum-free medium accumulate in G1-phase of the cell cycle. On addition of a growth-stimulating protein isolated from fetal calf serum they are triggered to proceed through the cycle, and they resume DNA-synthesis 15 to 20 hours later. In this paper it is demonstrated that the surface membrane potential difference (PD) decreases immediately after changing serum-free medium against culture medium containing either calf serum or the isolated serum protein; the original PD is restored 2 to 3 hours later. Serumprotein without growthstimulating activity does not affect the PD.A permanent rat cell line which grows independently of serum also has been tested. The PD of these cells is not significantly influenced by calf serum.

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