EVIDENCE FOR NEGATIVE FEEDBACK IN THE CONTROL OF ETHANOLAMINE BIOSYNTHESIS IN EXCISED TOMATO ROOTS

1959 ◽  
Vol 37 (5) ◽  
pp. 1071-1083 ◽  
Author(s):  
William G. Boll
Keyword(s):  
Amino Acids ◽  
Yeast Extract ◽  
Negative Feedback ◽  
Culture Media ◽  
Vitamin B ◽  
Tomato Roots ◽  
Carry Over

The isolation of a clone of excised tomato roots (clone R3), and the modifications of White's medium necessary for successful culture of this clone, are described. The medium includes pyridoxin. Either ethanolamine, dimethylethanolamine, glycine, L-serine, L-valine, DL-norleucine, or L-isoleucine (and possibly L-tryptophane) replaced pyridoxin to a greater or lesser extent. L-Alanine, L-lysine, and L-threonine did not replace pyridoxin. The replacement of pyridoxin by ethanolamine is not dependent upon the carry-over of pyridoxin in the inoculum and clone R3 has been subcultured for over a year in a medium containing ethanolamine but no added pyridoxin. Explanations of this fact are given.Nutritional experiments are described in which ethanolamine and amino acids, which will also partly replace pyridoxin, were supplied together in the absence of pyridoxin. The results support the hypothesis that exogenous ethanolamine leads to the loss of a vitamin B6 dependent enzyme necessary for the biosynthesis of ethanolamine. The results are of incidental interest when considering the use of complex additives (e.g. yeast extract) in culture media, and to the explanation of toxicity of natural metabolites.

DECOMPOSITION OF CHLORO-SUBSTITUTED ALIPHATIC ACIDS BY SOIL BACTERIA

1957 ◽  
Vol 3 (2) ◽  
pp. 151-164 ◽  
Author(s):  
H. L. Jensen
Keyword(s):  
Amino Acids ◽  
Yeast Extract ◽  
Soil Bacteria ◽  
Basal Medium ◽  
Soil Extract ◽  
Taxonomic Position ◽  
Vitamin B ◽  
Selective Media ◽  
Aliphatic Acids

Three groups of bacteria capable of decomposing chloro-substituted aliphatic acids were isolated from soil by means of selective media. A group of Pseudomonas-like bacteria (A) decomposed monochloroacetate (and monobromoacetate) readily in media with yeast extract, peptone, or amino acids. They also decomposed α-monochloropropionate with moderate vigor, but had little effect on dichloro-acetate and -propionate, and none on trichloroacetate. A non-sporeforming bacterium of uncertain taxonomic position (B) was able to decompose trichloroacetate in media containing soil extract or vitamin B12, and also in basal medium when associated with vitamin B12-producing strains of Streptomyces. Dichloroacetate was only slightly attacked, and monochloroacetate and α-dichloropropionate not at all. A group of bacteria (C) apparently belonging to Agrobacterium decomposed α-dichloropropionate and dichloroacetate, but was less active towards α-monochloropropionate, and did not attack mono- and tri-chloroacetate. The organisms of groups B and C grew only feebly in ordinary media. The decomposition of monochloroacetate, trichloroacetate, and α-dichloropropionate in soil was accelerated by addition of cell suspensions of groups A, B, and C, respectively. The organisms seemed to be more active in the soil than in vitro.

Roquefortine C Occurrence in Blue Cheese

2001 ◽  
Vol 64 (2) ◽  
pp. 246-251 ◽  
Author(s):  
CARLO FINOLI ◽  
ANGELA VECCHIO ◽  
ANTONIETTA GALLI ◽  
IVAN DRAGONI
Keyword(s):  
Yeast Extract ◽  
Culture Media ◽  
Penicillium Roqueforti ◽  
Blue Cheese ◽  
Penicillium Crustosum ◽  
Sucrose Medium ◽  
Low Toxicity ◽  
Yeast Extract Sucrose ◽  
Roquefortine C

Several strains of Penicillium are used for the production of mold-ripened cheeses, and some of them are able to produce mycotoxins. The aims of the research were the determination of roquefortine C and PR toxin in domestic and imported blue cheeses, the identification of the penicillia used as starter, and the investigation of their capacity for producing toxins in culture media. Roquefortine C was always found in the cheeses at levels ranging from 0.05 to 1.47 mg/kg, whereas the PR toxin was never found. The identification of the fungal strains present in the domestic cheeses included Penicillium glabrum, Penicillium roqueforti, and Penicillium cyclopium in the Gorgonzola “dolce” and Penicillium roqueforti in the Gorgonzola “naturale”; in one case, the presence of Penicillium crustosum was observed. The strains isolated from the foreign cheeses belonged to P. roqueforti. The strains were able to produce between 0.18 and 8.44 mg/liter of roquefortine in yeast extract sucrose medium and between 0.06 and 3.08 mg/liter and less than 0.05 mg/liter when inoculated in milk at 20°C for 14 days and 4°C for 24 days, respectively. Linear relations between production of roquefortine in culture media and cheeses did not emerge. PR toxin ranged from less than 0.05 to 60.30 mg/liter in yeast extract sucrose medium and was produced in milk at 20°C from only one strain. The low levels and the relatively low toxicity of roquefortine make the consumption of blue cheese safe for the consumer.

Effect of Amino Acids, of Vitamin B Complex and Other Compounds on Respiration of Bakers'Yeast

1940 ◽  
Vol 44 (2) ◽  
pp. 547-551 ◽  
Author(s):  
E. S. Cook ◽  
E. M. Walter ◽  
S. M. R. Eilert
Keyword(s):  
Amino Acids ◽  
Vitamin B

Amino acid metabolism of myeloma cells in culture

1976 ◽  
Vol 21 (3) ◽  
pp. 609-615
Author(s):  
R.S. Roberts ◽  
H.W. Hsu ◽  
K.D. Lin ◽  
T.J. Yang
Keyword(s):  
Amino Acids ◽  
Acid Metabolism ◽  
Culture Media ◽  
Growth Yield ◽  
Media Analysis ◽  
Sodium Pyruvate ◽  
Isoleucine Leucine ◽  
Myeloma Protein ◽  
Simple Modification ◽  
Myeloma Cells

The growth of myeloma cells in Leibovitz medium supplemented with 20% serum was limited by the depletion of glutamine. A simple modification of the Leibovitz medium by increasing the concentrations of glutamine, lysine, isoleucine, leucine, sodium pyruvate, galactose, and vitamins resulted in over 100% increase in cell growth yield. The total myeloma protein produced by the cells was increased by approximately 90% in modified Leibovitz media. Analysis of spent culture media for 19 amino acids showed that the concentrations of 8 amino acids were reduced; those of 5 amino acids were increased and the other 6 did not change significantly.

A noble extended stochastic logistic model for cell proliferation with density-dependent parameters

2021 ◽  
Author(s):  
Trina Roy ◽  
Sinchan Ghosh ◽  
Bapi Saha ◽  
Sabyasachi Bhattacharya
Keyword(s):  
Cell Proliferation ◽  
Cell Density ◽  
Negative Feedback ◽  
Deterministic Model ◽  
Culture Media ◽  
Logistic Growth ◽  
Density Dependent ◽  
Proposed Model ◽  
Dependent Cell ◽  
Growth Inhibiting

Abstract Cell proliferation often experiences a density-dependent intrinsic proliferation rate (IPR) and negative feedback from growth-inhibiting molecules in culture media. The lack of flexible models with explanatory parameters fails to capture such a proliferation mechanism. We propose an extended logistic growth law with the density-dependent IPR and additional negative feedback. The extended parameters of the proposed model can be interpreted as density-dependent cell-cell cooperation and negative feedback on cell proliferation. Moreover, we incorporate further density regulation for flexibility in the model through environmental resistance on cells. The proposed growth law has similarities with the strong Allee model and harvesting phenomenon. We also develop the stochastic analog of the deterministic model by representing possible heterogeneity in growth-inhibiting molecules and environmental perturbation of the culture setup as correlated multiplicative and additive noises. The model provides a maximum sustainable stable cell density (MSSCD) and a new fitness measure for proliferative cells. The proposed model shows superiority to the logistic law after fitting to real cell culture datasets. We illustrate both MSSCD and the new cell fitness for a range of parameters. The cell density distributions reveal the chance of overproliferation, underproliferation, or decay for different parameter sets under the deterministic and stochastic setups.

scholarly journals Visualizing Cancer Cell Metabolic Dynamics Regulated With Aromatic Amino Acids Using DO-SRS and 2PEF Microscopy

2021 ◽  
Vol 8 ◽  
Author(s):  
Pegah Bagheri ◽  
Khang Hoang ◽  
Anthony A. Fung ◽  
Sahran Hussain ◽  
Lingyan Shi
Keyword(s):  
Oxidative Stress ◽  
Amino Acids ◽  
Protein Synthesis ◽  
Spatial Distribution ◽  
Lipid Droplets ◽  
De Novo ◽  
Culture Media ◽  
Aromatic Amino Acids ◽  
Unsaturated Lipids ◽  
Metabolic Activities

Oxidative imbalance plays an essential role in the progression of many diseases that include cancer and neurodegenerative diseases. Aromatic amino acids (AAA) such as phenylalanine and tryptophan have the capability of escalating oxidative stress because of their involvement in the production of Reactive Oxygen Species (ROS). Here, we use D2O (heavy water) probed stimulated Raman scattering microscopy (DO-SRS) and two Photon Excitation Fluorescence (2PEF) microscopy as a multimodal imaging approach to visualize metabolic changes in HeLa cells under excess AAA such as phenylalanine or trytophan in culture media. The cellular spatial distribution of de novo lipogenesis, new protein synthesis, NADH, Flavin, unsaturated lipids, and saturated lipids were all imaged and quantified in this experiment. Our studies reveal ∼10% increase in de novo lipogenesis and the ratio of NADH to flavin, and ∼50% increase of the ratio of unsaturated lipids to saturated lipid in cells treated with excess phenylalanine or trytophan. In contrast, these cells exhibited a decrease in the protein synthesis rate by ∼10% under these AAA treatments. The cellular metabolic activities of these biomolecules are indicators of elevated oxidative stress and mitochondrial dysfunction. Furthermore, 3D reconstruction images of lipid droplets were acquired and quantified to observe their spatial distribution around cells’ nuceli under different AAA culture media. We observed a higher number of lipid droplets in excess AAA conditions. Our study showcases that DO-SRS imaging can be used to quantitatively study how excess AAA regulates metabolic activities of cells with subcellular resolution in situ.

scholarly journals The Capsid (ORF2) Protein of Hepatitis E Virus in Feces Is C-Terminally Truncated

Pathogens ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 24
Author(s):  
Takashi Nishiyama ◽  
Koji Umezawa ◽  
Kentaro Yamada ◽  
Masaharu Takahashi ◽  
Satoshi Kunita ◽  
...  
Keyword(s):  
Amino Acids ◽  
Cell Culture ◽  
Structure Prediction ◽  
Hepatitis E Virus ◽  
Culture Media ◽  
Molecular Size ◽  
Hepatitis E ◽  
Terminal Region ◽  
Translation Product ◽  
Orf2 Protein

The hepatitis E virus (HEV) is a causative agent of hepatitis E. HEV virions in circulating blood and culture media are quasi-enveloped, while those in feces are nonenveloped. The capsid (ORF2) protein associated with an enveloped HEV virion is reported to comprise the translation product of leucine 14/methionine 16 to 660 (C-terminal end). However, the nature of the ORF2 protein associated with fecal HEV remains unclear. In the present study, we compared the molecular size of the ORF2 protein among fecal HEV, cell-culture-generated HEV (HEVcc), and detergent-treated protease-digested HEVcc. The ORF2 proteins associated with fecal HEV were C-terminally truncated and showed the same size as those of the detergent-treated protease-digested HEVcc virions (60 kDa), in contrast to those of the HEVcc (68 kDa). The structure prediction of the ORF2 protein (in line with previous studies) demonstrated that the C-terminal region (54 amino acids) of an ORF2 protein is in flux, suggesting that proteases target this region. The nonenveloped nondigested HEV structure prediction indicates that the C-terminal region of the ORF2 protein moves to the surface of the virion and is unnecessary for HEV infection. Our findings clarify the maturation of nonenveloped HEV and will be useful for studies on the HEV lifecycle.

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