• Molecules and Cells
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• 제42권10호
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• pp.711-720
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• 2019

Sink strength optimizes sucrose import, which is fundamental to support developing seed grains and increase crop yields, including those of rice (Oryza sativa). In this regard, little is known about the function of vacuolar invertase (VIN) in controlling sink strength and thereby seed size. Here, in rice we analyzed mutants of two VINs, OsVIN1 and OsVIN2, to examine their role during seed development. In a phenotypic analysis of the T-DNA insertion mutants, only the OsVIN2 mutant osvin2-1 exhibited reduced seed size and grain weight. Scanning electron microscopy analysis revealed that the small seed grains of osvin2-1 can be attributed to a reduction in spikelet size. A significant decrease in VIN activity and hexose level in the osvin2-1 spikelets interfered with spikelet growth. In addition, significant reduction in starch and increase in sucrose, which are characteristic features of reduced turnover and flux of sucrose due to impaired sink strength, were evident in the pre-storage stage of osvin2-1 developing grains. In situ hybridization analysis found that expression of OsVIN2 was predominant in the endocarp of developing grains. A genetically complemented line with a native genomic clone of OsVIN2 rescued reduced VIN activity and seed size. Two additional mutants, osvin2-2 and osvin2-3 generated by the CRISPR/Cas9 method, exhibited phenotypes similar to those of osvin2-1 in spikelet and seed size, VIN activity, and sugar metabolites. These results clearly demonstrate an important role of OsVIN2 as sink strength modulator that is critical for the maintenance of sucrose flux into developing seed grains.

• Journal of Microbiology and Biotechnology
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• 제27권5호
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• pp.939-942
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• 2017

The cellular composition and metabolic compounds of Leuconostoc mesenteroides ATCC 8293 were analyzed after cultivation in an anaerobic chemostat. The macromolecular composition was 24.4% polysaccharide, 29.7% protein, 7.9% lipid, 2.9% DNA, and 7.4% RNA. Its amino acid composition included large amounts of lysine, glutamic acid, alanine, and leucine. Elements were in the order of C > O > N > H > S. The metabolites in chemostat culture were lactic acid (73.34 mM), acetic acid (7.69 mM), and mannitol (9.93 mM). These data provide a first view of the cellular composition of L. mesenteroides for use in metabolic flux analysis.

• Journal of Plant Biotechnology
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• 제37권2호
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• pp.205-211
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• 2010

Yield productivity of staple crops must be increased at least 50% by 2050, in order to feed the world population which is expected to reach 90 billions. Photosynthetic carbon assimilation and carbohydrate metabolism leading to the production of starch would be the final frontier to quest for new sources of technology enabling such a drastic increase of crop productivity. In this review, attempts to genetically engineer plant photosynthetic carbon reduction cycle and metabolic pathways to increase starch production are introduced.

• Korean Journal of Radiology
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• 제25권5호
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• pp.459-472
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• 2024

Hyperpolarized (HP) carbon-13 (¹³C) MRI represents an innovative approach for noninvasive, real-time assessment of dynamic metabolic flux, with potential integration into routine clinical MRI. The use of [1-¹³C]pyruvate as a probe and its conversion to [1-¹³C]lactate constitute an extensively explored metabolic pathway. This review comprehensively outlines the establishment of HP ¹³C-MRI, covering multidisciplinary team collaboration, hardware prerequisites, probe preparation, hyperpolarization techniques, imaging acquisition, and data analysis. This article discusses the clinical applications of HP ¹³C-MRI across various anatomical domains, including the brain, heart, skeletal muscle, breast, liver, kidney, pancreas, and prostate. Each section highlights the specific applications and findings pertinent to these regions, emphasizing the potential versatility of HP ¹³C-MRI in diverse clinical contexts. This review serves as a comprehensive update, bridging technical aspects with clinical applications and offering insights into the ongoing advancements in HP ¹³C-MRI.

• 대한핵의학회지
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• 제27권1호
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• pp.104-111
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• 1993

Trace elements are important components in the biological system, as a structural material and metabolic controller. Neutron activation analysis (NAA) with high neutron flux and high energy resolution Ge (Li) detector coupled to multichannel analyzer (MCA) has been one of the most accurate method for the determination of ultra-trace level components, and is applicable to biological material. In human body, the NAA can be used for quantitation of trace elements in various organs and tissue with endocrinological and metabolic disease and industrial metal poisoning. In this study, Triga Mark III nuclear reactor in Korea Atomic Research Institute was used for quantitation of trace eleement in human lung cancer tissues by neutron activation analysis. In the squamous cell carcinoma tissues, Br, Hg, La, Sb, Sc, Cl, Fe and I content were lower than normal lung tissues, and K, Rb and Se content were higher. In the adenocarcinoma tissues, Fe, Au, La, Sc and Zn content were lower than normal lung tissues, and Rb, Co and Se content were higher. Rb content was higher in the adenocarcinoma tissues than in the squamous cell carcinoma tissues. Fe and Na content were higher in the squamous cell carcinoma tissues than in the adenocarcinoma tissues.

• Journal of Microbiology and Biotechnology
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• 제16권6호
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• pp.993-998
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• 2006

We earlier suggested a hierarchical regulatory network using defined modeling symbols and weights in order to improve the flux balance analysis (FBA) with regulatory events that were represented by if-then rules and Boolean logic. In the present study, the simulation results of the models, which were developed and improved from the previou model by incorporating a hierarchical regulatory network into the FBA, were compared with the experimental outcome of an aerobic batch growth of E. coli on glucose and tryptophan. From the experimental result, a diauxic growth curve was observed, reflecting growth resumption, when tryptophan was used as an alternativee after the supply of glucose was exhausted. The model parameters, the initial concentration of substrates (0.92 mM glucose and 1 mM tryptophan), cell density (0.0086 g biomass/1), the maximal uptake rates of substrates (5.4 mmol glucose/g DCW h and 1.32 mmol tryptophan/g DCW h), and lag time (0.32 h) were derived from the experimental data for more accurate prediction. The simulation results agreed with the experimental outcome of the temporal profiles of cell density and glucose, and tryptophan concentrations.

• Journal of Microbiology and Biotechnology
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• 제15권3호
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• pp.551-559
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• 2005

The recent rapid increase in genomic data related to many microorganisms and the development of computational tools to accurately analyze large amounts of data have enabled us to design several kinds of simulation approaches for the complex behaviors of cells. Among these approaches, dFBA (dynamic flux balance analysis), which utilizes FBA, differential equations, and regulatory events, has correctly predicted cellular behaviors under given environmental conditions. However, until now, dFBA has centered on substrate concentration, cell growth, and gene on/off, but a detailed hierarchical structure of a regulatory network has not been taken into account. The use of Boolean rules for regulatory events in dFBA has limited the representation of interactions between specific regulatory proteins and genes and the whole transcriptional regulation mechanism with environmental change. In this paper, we adopted the operon as the basic structure, constructed a hierarchical structure for a regulatory network with defined fundamental symbols, and introduced a weight between symbols in order to solve the above problems. Finally, the total control mechanism of regulatory elements (operons, genes, effectors, etc.) with time was simulated through the linkage of dFBA with regulatory network modeling. The lac operon, trp operon, and tna operon in the central metabolic network of E. coli were chosen as the basic models for control patterns. The suggested modeling method in this study can be adopted as a basic framework to describe other transcriptional regulations, and provide biologists and engineers with useful information on transcriptional regulation mechanisms under extracellular environmental change.

• Journal of Ginseng Research
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• 제38권2호
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• pp.97-105
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• 2014

Background: Understanding what causes changes in the flux of free fatty acids (FFA) is important to elucidate the etiology of metabolic syndrome. The first aim of this study was to test whether or not hormones and the autonomic nervous system influence blood FFA levels. A secondary aim was to test by means of a multiple group path analysis whether the consumption of fermented red ginseng (FRG; Panax ginseng) would influence those causal relationships. Methods: Ninety-three postmenopausal women (age 50e73 yr) were randomly divided into two groups. One group (44 women; age, $58.4{\pm}5.9yr$; body mass index, $3.6{\pm}2.5kg/m^2$) was supplied place capsules and the other group (49 women, age $58.4{\pm}5.5yr$; body mass index, $22.9{\pm}2.4kg/m^2$) was supplied FRG capsules. Both prior to and after the study (2 wk), blood samples were collected from the participants and several blood variables were measured and analyzed. Results: Squared multiple correlations of FFA were 0.699 in the placebo group and 0.707 in the FRG group. The unstandardized estimate of estradiol (E2) for FFA was 0.824 in both groups. Conclusion: The path coefficients of cortisol and the branchial pulse for FFA were significantly different between the FRG group and the placebo group.

• 한국미생물·생명공학회지
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• 제26권5호
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• pp.387-392
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• 1998

B. lactofermentum의 lysine 생합성에 있어서 DDH경로 및 ddh gene이 지닌 중요성을 조사하기 위하여, site-specific mutagenesis technique를 통하여 B. lactofermentum의 ddh gene을 disruption함으로서 DDH 경로를 차단시켰다. B. lactofermentum ddh mutant는 wild type 및 AEC내성 균주보다 성장이 매우 저조하였으며 lysine 생산량에서도 급격한 저하를 가져왔다. 이와 같이 B. lactofermentum이 DAP 경로만을 가졌을 때 세포의 성장 및 lysine 생산량에 있어서 극적인 저하를 가져왔기 때문에 B. lactofermentum에서의 DDH 경로는 meso-DAP 및 lysine 생합성에 있어 필수적인 경로로 작용한다는 것을 확인하였다. 그러므로 C. glutamicum과 B. lactofermentum과 같은 corynebacteria가 lysine을 많이 생산하는 것은 DDH 경로가 부가적으로 존재하기 때문이며, 이러한 DDH 경로는 metabolic flux가 증가되면 중간 대사물을 lysine으로 변화시키는 중요한 경로로 작용할 것이라 사료된다.

• Molecules and Cells
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• 제27권6호
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• pp.641-649
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• 2009

Pyrophosphate:fructose-6-phosphate 1-phosphotransferase (PFP) catalyzes the reversible interconversion of fructose-6-phosphate and fructose-1,6-bisphosphate, a key step in the regulation of the metabolic flux toward glycolysis or gluconeogenesis. To examine the role of PFP in plant growth, we have generated transgenic Arabidopsis plants that either overexpress or repress Arabidopsis PFP subunit genes. The overexpressing lines displayed increased PFP activity and slightly faster growth relative to wild type plants, although their photosynthetic activities and the levels of metabolites appeared not to have significantly changed. In contrast, the RNAi lines showed significantly retarded growth in parallel with the reduced PFP activity. Analysis of photosynthetic activity revealed that the growth retardation phenotype of the RNAi lines was accompanied by the reduced rates of $CO_2$ assimilation. Microarray analysis of our transgenic plants further revealed that the altered expression of $AtPFP{\beta}$ affects the expression of several genes involved in diverse physiological processes. Our current data thus suggest that PFP is important in carbohydrate metabolism and other cellular processes.