• BMB Reports
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• v.32 no.2
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• pp.140-146
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• 1999

When murine fibrosarcoma L929 cells, a TNF-sensitive cell line, were treated with recombinant human tumor necrosis factor-$\alpha$ (rhTNF-$\alpha$), the activities of glycolytic regulatory enzymes and lactate dehydrogenase increased up to 100-150% compared to the control L929 cells after TNF treatment. By using various metabolic inhibitors and activators, it was found that cAMP-dependent protein kinase is responsible for the increase of activities of the glycolytic enzymes. The activities of glycolytic regulatory enzymes and lactate dehydrogenase of TNF-resistant A549 cells, a human lung carcinoma cell line, did not increase significantly compared to TNF-sensitive L929 cells upon TNF treatment. In contrast, the pyruvate carboxylase activities of A549 cells, but not L929 cells, increased up to 30~40% after TNF treatment. The data suggest that pyruvate carboxylase activity may contribute to the compensation of energy loss mediated by TNF treatment in TNF-resistant A549 cells.

• ALGAE
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• v.32 no.2
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• pp.161-170
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• 2017

Fourier Transform Infrared (FTIR) spectroscopy was used to study carbon allocation patterns in response to N-starvation in the nearly ubiquitous diatom Chaetoceros muellerii. The role of gene expression, protein synthesis and transamination on the organic composition of cells was tested by using specific inhibitors. The results show that inhibition of key processes in algal metabolism influence the macromolecular composition of cells and and prior cell nutritional state can influence a cell's response to changing nutrient availability. The allocation of C can thus lead to different organic composition depending on the nutritional context, with obvious repercussions for the trophic web. This also shows that C allocation in algal cells is highly flexible and that C (and the energy associated with its allocation) can be variably and rapidly partitioned in algal cells in response to relatively short term perturbations. Furthermore, the data confirm and extend the utility of infrared spectroscopy as a probe of the metabolic state of autotrophic cells.

• Microbiology and Biotechnology Letters
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• v.24 no.4
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• pp.385-392
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• 1996

Bacillus stearotheymophilus, a potent xylanolytic bacterium isolated from soil, was tested for the strain's strategies of pentose utilization and the evidence of substrate preferences. The strain metabolized glucose, xylose, ribose, maltose, cellobiose, sucrose, arabinose and xylitol. The efficacy of the sugars as a carbon and energy source in this strain was of the order named above. The organism, however, could not grow on glycerol as a sole growth substrate. During cultivation on a mixture of glucose and xylose or arabinose, the major hydrolytic products of xylan, B. stearothermophilus displayed classical diauxic growth in which glucose was utilized during the first phase. On the other hand, the pentose utilization was prevented immediately upon addition of glucose. Cellobiose was preferred over xylose or arabinose. In contrast, maltose and pentose were co-utilized, and also no preference on between xylose and arabinose. Enzymatic studies indicated that B. stearothermophilus possessed constitutive hexokinase, a key enzyme of the glucose metabolic system. While, the production of $^{D}$-xylose isomerase, $^{D}$-xylulokinase and $^{D}$-arabinose isomerase essential for pentose phosphate pathway were induced by xylose, xylan, and xylitol but repressed by glucose. Taken together, the results suggested that the sequential utilization of B. stearothermophilus would be mediated by catabolite regulatory mechanisms such as catabolite inhibition or inducer exclusion.

• Nutritional Sciences
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• v.5 no.4
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• pp.184-189
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• 2002

The effects of dietary Int levels on lipid metabolism under fixed P/S (1.3) and n-6/n-3 (5.1) fatty acid ratios were examined in rats using palm oil, soybean oil and perilla oil. These ratios correspond to the recommended composition of dietary fat for humans. The range of dietary fat levels was 5-20% by weight (11.8-39.3% of total energy). The levels of dietary fat did not influence the concentrations of serum and liver cholesterol, whereas the level of triglycerides was gradually elevated with increasing levels of dietary fat, especially in the liver. The fatty acid composition of tissue phosphatidylcholine seemed to vary with the different levels of fat. The ratio of linoleic acid to arachidonic acid was increased more significantly in the heart than in the liver. In adipose tissue total lipids, the percentages of saturated and monounsaturated fatty acids decreased, whereas the percentage of polyunsaturated fatty acid increased, with increasing dietary Int levels. In addition, though the level of aortic prostacyclin was not uniformly affected by increasing dietary fat levels, thromboxane A2 production by platelets tended to increase with higher levels of dietary fat, suggesting an increased risk of thrombosis in this situation. Thus, even though dietary fat may have desirable compositions of fatty acids, these excessive consumption can produce unfavorable metabolic responses.

• BMB Reports
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• v.39 no.4
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• pp.394-399
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• 2006

The transport of putrescine into a moderately salt tolerant cyanobacterium Synechocystis sp. PCC 6803 was characterized by measuring the uptake of radioactively-labeled putrescine. Putrescine transport showed saturation kinetics with an apparent $K_m$ of $92{\pm}10\;{\mu}M$ and $V_{max}$ of $0.33{\pm}0.05\;nmol/min/mg$ protein. The transport of putrescine was pH-dependent with highest activity at pH 7.0. Strong inhibition of putrescine transport was caused by spermine and spermidine whereas only slight inhibition was observed by the addition of various amino acids. These results suggest that the transport system in Synechocystis sp. PCC 6803 is highly specific for polyamines. Putrescine transport is energy-dependent as evidenced by the inhibition by various metabolic inhibitors and ionophores. Slow growth was observed in cells grown under salt stress. Addition of low concentration of putrescine could restore growth almost to the level observed in the absence of salt stress. Upshift of the external osmolality generated by either NaCl or sorbitol caused an increased putrescine transport with an optimum 2-fold increase at 20 mosmol/kg. The stimulation of putrescine transport mediated by osmotic upshift was abolished in chloramphenicol-treated cells, suggesting possible involvement of an inducible transport system.

• Journal of Microbiology and Biotechnology
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• v.19 no.5
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• pp.447-454
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• 2009

The transport of spermidine into a cyanobacterium, Synechocystis sp. pec 6803, was characterized by measuring the uptake of $^{14}C$-spermidine. Spermidine transport was shown to be saturable with an apparent affinity constant ($K_m$) value of $67{\mu}M$ and a maximal velocity ($V_{max}$) value of 0.45 nmol/min/mg protein. Spermidine uptake was pH-dependent with the pH optimum being 8.0. The competition experiment showed strong inhibition of spermidine uptake by putrescine and spermine, whereas amino acids were hardly inhibitory. The inhibition kinetics of spermidine transport by putrescine and spermine was found to be noncompetitive with $K_i$ values of 292 and $432{\mu}M$, respectively. The inhibition of spermidine transport by various metabolic inhibitors and ionophores suggests that spermidine uptake is energy-dependent. The diminution of cell growth was observed in cells grown at a high concentration of NaCl. Addition of a low concentration of spermidine at 0.5 mM relieved growth inhibition by salt stress. Upshift of the external osmolality generated by either NaCl or sorbitol caused an increased spermidine transport with about 30-40% increase at 10 mosmol/kg upshift.

• Journal of Microbiology and Biotechnology
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• v.13 no.1
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• pp.90-98
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• 2003

In vivo $^31p$ Nuclear Magnetic Resonance ($^31p$NMR) and metabolic studies were carried out on an acetic acid tolerant mutant, Zymomonas mobilis $ZM4/Ac^R$, and compared to those of the parent strain, Z. mobilis ZM4, to evaluate possible mechanisms of acetic acid resistance. This investigation was initiated to determine whether or not the mutant strain might be used as a suitable recombinant host far ethanol production from lignocellulose hydrolysates containing various inhibitory compounds. $ZM4/Ac^R$ showed multiple resistance to other lignocellulosic toxic compounds such as syringaldehyde, furfural, hydroxymethyl furfural, vanillin, and vanillic acid. The mutant strain was resistant to higher concentrations of ethanol or lower pH in the presence of sodium acetate, compared to ZM4 which showed more additive inhibition. in vivo $^31p$ NMR studies revealed that intracellular acidification and de-energization were two mechanisms by which acetic acid exerted its inhibitory effect. For $ZM4/Ac^R$, the internal pH and the energy status were less affected by sodium acetate compared to the parent strain. This resistance to pH change and de-energization caused by acetic acid is a possible explanation for the development of resistance by this strain.

• Microbiology and Biotechnology Letters
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• v.37 no.4
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• pp.306-315
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• 2009

Due to the depleting petroleum reserve, recurring energy crisis, and global warming, it is necessary to study the development of white biotech-based aromatic chemical feedstock from renewable biomass for replacing petroleum-based one. In particular, the production of aromatic intermediates and derivatives in biosynthetic pathway of aromatic amino acids from glucose might be replaced by the production of petrochemical-based aromatic chemical feedstock including benzene-derived aromatic compounds. In this review, I briefly described the production technology for hydroquinone, catechol, adipic acid, shikimic acid, gallic acid, pyrogallol, vanillin, p-hydroxycinnamic acid, p-hydroxystyrene, p-hydroxybenzoic acid, indigo, and indole 3-acetic acid using metabolic engineering, bioconversion, and chemical process. The problems and possible solutions regarding development of production technology for competitive white biotech-based aromatic compounds were also discussed.

• Journal of Applied Biological Chemistry
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• v.54 no.2
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• pp.101-107
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• 2011

Aging in females is associated with a reduced metabolic function, increased incidence of neurodegenerative diseases, and cognitive dysfunction, as a result of loss in gonadal function. The change can alter the states of phosphorylation on the proteins, which cause dramatic changes in the cellular location or activity of the proteins. In this study, the differential phosphorylation of the proteins responsible for the functions related to cognition was studied using the ovariectomized adult rats. Phosphoproteomic analysis using the cerebral and hippocampal tissues could identify 51 differentially phosphorylated proteins including 12 proteins for energy metabolism, 8 cytoskeletal proteins, 6 signaling proteins, and other functional proteins in the ovariectomized rats. Further, anti-oxidative enzymes, superoxide dismutase and peroxiredoxin-2, which are known to be inactivated by phosphorylation, were found to be differentially phosphorylated in the cerebellum and hippocampus of the ovariectomized rats, respectively. Many of the deactivated proteins by differential phosphorylation identified in this study were overlapped to those of Alzheimer's disease cases. These results will provide information for neurodegenerative learning and memory impairments in women as brought about by menopause.

• Journal of Microbiology and Biotechnology
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• v.2 no.2
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• pp.141-151
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• 1992

Physiological changes of the murine hybridoma cell line $S3H5/\gamma{2bA2}$ during adaptation to RPMI 1640 medium with 1%(v/v) fetal bovine serum were characterized in terms of cell growth, antibody production, morphology, and metabolic quotients. Cells adapted to 1% serum medium in T-flasks became sensitive to shear induced by mechanical agitation and required at least 5% serum in the medium or spent medium for cell growth in spinner flasks, while cells adapted to 10% serum medium in T-flasks could grow in 1% serum medium in spinner flasks. Consequently, long-term adaptation to low serum media may not give the expected growth enhancement. After adaptation to 1% serum medium, changes in cell morphology were observed. The cells in 10% serum medium were uniform and circular, while cells in 1% medium were irregularly shaped. The DNA contents, which were measured by flow cytometry, were almost constant among the cells in the range of 1% to 10%. Further, no significant changes in energy metabolism and specific monoclonal antibody production rate were observed among these cells.