• The Korean Journal of Food And Nutrition
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• v.15 no.2
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• pp.112-118
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• 2002

Sporulation in the fission yeast Schizosaccharomyces pombe has been regarded as an important model of cellular development and differentiation. S. pombe cells proliferate by mitosis and binary fission on growth medium. Deprivation of nutrients especially nitrogen sources, causes the cessation of mitosis and initiates sexual reproduction by matting between two sexually compatible cell types. Meiosis is then followed in a diploid cell in the absence of nitrogen source. DNA fragment complemented with the mutations of sporulation gene was isolated from the S. pombe gene library constructed in the vector, pDB 248' and designated as pDB(spo5)1. We futher analyzed six recombinant plasmids, pDB(spo5)2, pDB(spo5)3, pDB(spo5)4, pDB(spo5)5, pDB (spo5)6, pDB(spo5)7 and found each of these plasmids is able to rescue the spo5-2, spo5-3, spo5-4, spo5-5, spo5-6, spo5-7 mutations, respectively. Mapping of the integrated plasmid into the homologous site of the S. pombe chromosomes demonstrated that pDB(spo5)1, and pDB(spu5)Rl contained the spo5 gene. Transcripts of spo5 gene were analyzed by Northern hybridization. Two transcripts of 3.2 kb and 2.5kb were detected with 5kb Hind Ⅲ fragment containing a part of the spo5 gene as a probe. The small mRNA(2.5kb) appeared only when a wild-type strain was cultured in the absence of nitrogen source in which condition the large mRNA (3.2kb) was produced constitutively. Appearance of a 2.5kb spo5-mRNA depends upon the function of the meil, mei2 and mei3 genes.

• Korean Journal of Microbiology
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• v.52 no.3
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• pp.278-285
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• 2016

The bifunctional PheA protein, having chorismate mutase and prephenate dehydratase (CMPD) activities, is one of the key regulatory enzymes in the aromatic amino acid biosynthesis in Escherichia coli, and is negatively regulated by an end-product, phenyalanine. Therefore, PheA protein has been thought as useful for protein engineering to utilize mass production of essential amino acid phenylalanine. To obtain feedback resistant PheA protein against phenylalanine, we mutated by using random mutagenesis, extensively screened, and obtained $pheA^{FBR}$ gene encoding a feedback resistant PheA protein. The mutant PheA protein contains substitution of Leu to Phe at the position of 118, displaying that higher affinity (about $290{\mu}M$) for prephenate in comparison with that (about $850{\mu}M$) of wild type PheA protein. Kinetic analysis showed that the saturation curve of $PheA^{FBR}$ against phenyalanine is hyperbolic rather than that of $PheA^{WT}$, which is sigmoidal, indicating that the L118F mutant enzyme has no cooperative effects in prephenate binding in the presence of phenylalanine. In vitro enzymatic assay showed that the mutant protein exhibited increased activity by above 3.5 folds compared to the wild type enzyme. Moreover, L118F mutant protein appeared insensitive to feedback inhibition with keeping 40% of enzymatic activity even in the presence of 10 mM phenylalanine at which the activity of wild type $PheA^{WT}$ was not observed. The substitution of Leu to Phe in CMPD may induce significant conformational change for this enzyme to acquire feedback resistance to end-product of the pathway by modulating kinetic properties.

• Food Science and Preservation
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• v.24 no.2
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• pp.168-180
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• 2017

This study was performed to determine the rapid thawing method for reducing the thawing time of frozen pork loins and to examine the effects of supercooling on the microbiological, physicochemical, and sensory qualities of fresh and frozen-thawed pork during storage at -1.5, 4, and $15^{\circ}C$. Forced-air thawing at $4^{\circ}C$ was the most time-consuming process, whereas radio frequency thawing time was the shortest by dielectric heating. The supercooling storage temperature was chosen to be $-1.5^{\circ}C$ because microstructural damages were not observed in the pork sample after cooling at $-1.5^{\circ}C$ for 24 h. Fresh or frozen-thawed pork loins stored at $-1.5^{\circ}C$ had lower drip loss and total volatile base nitrogen, thiobarbituric acid-reactive substance, and Hunter b* levels than loins stored at 4 and $15^{\circ}C$. In addition, the least degree of increase in preexisting microorganisms counts of the fresh or frozen-thawed pork loin samples was obtained during supercooled storage at $-1.5^{\circ}C$. Sensory quality results of fresh and frozen-thawed pork loin samples stored at $-1.5^{\circ}C$ showed higher scores than the samples stored at 4 and $15^{\circ}C$. These data indicate that supercooling at $-1.5^{\circ}C$ in the meat processing industry would be effective for maintaining the quality of pork meats without ice crystal nucleation and formation.

• Journal of Plant Biotechnology
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• v.46 no.3
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• pp.236-245
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• 2019

Fruit ripening is a genetically programmed process involving a number of biochemical and physiological processes assisted by variations in gene expression and enzyme activities. This process generally affects the phytochemical profile and the bioactive principles in fruits and vegetables. To appraise the variation in bioactive principles of fruits from Rosa rugosa during its ripening process, we analyzed the changes in antioxidant and anti-elastase activities and polyphenolic compounds during the four ripening stages of fruits. Overall, an extract of unripe fruits contained the highest levels of total phenolic and flavonoid contents, radical scavenging activity, reducing power, oxygen radical antioxidant capacity, and elastase inhibitory activity, compared with the extracts of fruits at other stages of ripening. Additionally, we found that the reduction of flavonoid content occurs because of decreased transcriptional levels of genes involved in flavonoid biosynthesis pathway during the ripening process. Based on HPLC analysis, we found that the extract of unripe fruits contained the highest amount of myricetin, caffeic acid, chlorogenic acid, syringic acid, and p-coumaric acid and suggested that the antioxidant and anti-elastase activities of the extract obtained from stage 1, should be mediated by the presence of these compounds. Additionally, we analyzed the interaction sites and patterns between these compounds and elastase using the structure-based molecular docking approach, and suggested that chlorogenic acid strongly interacted with elastase. Together, these findings suggest that the maturity of fruits has profound effects on the pharmaceutical value of R. rugosa.

• Journal of Korean Society of Forest Science
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• v.86 no.3
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• pp.378-390
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• 1997

Ten total populations of Korean fir (Abies koreana Wilson) and Manshurian fir [A. nephrolepis (Traut.) Maxim.] were sampled from south Korea to investigate patterns of intraspecific variation in these species and to evaluate a recognition of the two species. Principal components analysis and cluster analysis were performed both on seed-cone data and on needle morphology data. The characters that contributed most to the separation between A. koreana and A. nephrolepis along three principal components axis were leaf width, length of seed, width of seed wing, length of seed wing, cone width, width of scale, and length of bract tip, but these characters were not diagnostic because of overlap in reality. Therefore, all these characters were not reliable in distinguishing these two taxa including bract position (exerted and recurved vs. exerted and straight). The individuals of A. koreana from Mt. Chi-ri appeared quite unique probably on account of its larger cone size and longer scale tip, while those from Mt. Hal-la of A. koreana were generally distinct from others in terms of their larger seed and seed wing and longer scale width. The Mt. Duk-yu specimens of A. korecana appeared somewhat smaller but more data were needed due to the small sampling size. Generally, the gradual clinal geographic trends made evident by the position of resin ducts in leaves of A. koreana can be detected. The southern populations, Mt. Hal-la (an insular population) were generally distinct from the northern populations (Mt. Chi-ri, Mt. Ga-ya and Mt. Duk-yu) in terms of their position of resin duct (medial, within mesophyll vs marginal, close to epidermis : 100% vs 75 or 50%). Although no sharp boundary separating these two species could be detected based on cone and needle morphology, the observed clinal pattern was distinct in northern populations of A. koreana and southern population of A. nephrnlepis. In a preceding study of the flavonoids variation of 20 species in eastern Asia, flavanone (5-deoxyflavanone) was found to be characteristic of A. faxoniana Rehder et Wilson, A. georgei Orr of China and A. koreana of Korea. A. faxoniana, which is assumed to be primitive species, has position of resin duct relative to both the medial and the marginal, while A. georgei and A. koreana are identified by marginal position of resin duct. With respect of foliar flavonoids chemistry, A. koreana was distinct from A. nephrolepis : the southmost samples (Mt. Hal-la and Mt. Chi-ri) contained additional flavonoids derivatives (mainly flavanone) that were not found in the northmost samples of A. nephrolepis except a few individuals from Mts. Seo-rak and Tae-bak populations of Kwang-won province. The presence of A. koreana type flavonoids in two Chinese species suggested that position of resin duct may be a phyletic character. Abies koreana including two Chinese taxa, exhibited the most elaborate and specialized flavonoids profile within the Abies in eastern Asia. Contrary to our initial expectations, the apparent intermediates between A. nephrolepis and A. koreana in Duk-yu and Ga-ya mountains were found. The pattern of variation on position of resin duct and flavonoids chemistry in these populations of A. kareana suggested that genetic interchange or natural hybridization had occurred between these two species. The evidence needed to resolve the status of this taxon is still inconclusive in our opinion until intermediate individuals from Mts. Duk-yu and Ga-ya show indication of hybridization between the two species.

• Korean Journal of Plant Taxonomy
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• v.41 no.1
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• pp.66-80
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• 2011

This study investigated the environmental factors and conducted a RAPD analysis for a better understanding of the environmental characteristics and regional genetic variation in samples from 18 different areas of Viola diamantiaca. The habitats are mostly located on the slopes of mountains facing north at an altitude ranging from 614 m to 1,462 m above sea level with angles of inclination ranging from 3 degrees to 30 degrees. A total of 268 vascular plant taxa are identified in 35 quadrates of 18 habitats. The importance value of V. diamantiaca is 11.58%, and four highly ranked species, Sasa borealis (5.61%), Meehania urticifolia (5.21%), Ainsliaea acerifolia (3.62%), Pseudostellaria palibiniana (3.60%) are considered to have an affinity with V. diamantiaca in their habitats. The degree of their average species diversity is 1.36, while this metric for their evenness and dominance are 0.89 and 0.07, respectively. The average field capacity of the soil is 25.99%, with organic matter at 17.47%, and the pH is 5.19. The soil texture was confirmed as sandy loam of eleven and loam of seven. The result of the RAPD analysis, among 78 bands amplified with a primer, 64 (84.6%) showed polymorphism. Eighteen populations could be classified into five groups with similarity coefficient values ranging from 0.53 to 0.86. The Mt. Jiri population, which is geographically segregated, shows basal branching within the 18 populations. Five populations, including two in the southern district in Gangwon-do and three in Chungcheongbuk-do, form a distinct clade. Four populations in the central district of Gangwon-do and Mt. Bohyeon in the Gyeongsangbuk-do clade form a sister to the clade containing two populations in Gyeonggi-do and five populations of the northern district in Gangwon-do. The Mt. Gariwang population is placed between the southern district and the central district in the Gangwon-do clades.

• Journal of Korea Water Resources Association
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• v.34 no.6
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• pp.659-672
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• 2001

Generally, design flood for a hydraulic structure is estimated using statistical analysis of runoff data. However, due to the lack of runoff data, it is difficult that the statistical method is applied for estimation of design flood. In this case, the synthetic unit hydrograph method is used generally and the models such as NYMO method, Snyder method, SCS method, and HYMO method have been widely used in Korea. In this study, these methods and KICT method, which is developed in year 2000, are compared and analyzed in 10 study areas. Firstly, peak flow and peak time of representative unit hydrograph and synthetic unit hydrograph in study area are compared, and secondly, the shape of unit hydrograph is compared using a root mean square error(RMSE). In Nakayasu method developed in Japan, synthetic unit hydrograph is very different from peak flow, peak time, and the shape of representative unit hydrograph, and KICT method(2000) is superior to others. Also, KICT method(2000) is superior to others in the aspects of using hydrologic and topographical data. Therefore, Nakayasu method is not a proper in hydrological practice. Moreover, it is considered that KICT model is a better method for the estimation of design flood. However, if other model, i.e. SCS method, Nakayasu method, and HYMO method, is used, parameters or regression equations must be adjusted by analysis of real data in Korea.

• Journal of Plant Biotechnology
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• v.38 no.2
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• pp.176-185
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• 2011

Rice is one of the most important crop in the world, in particular for food resources. With its small genome size of 383 Mb, the Oryza sativa is a model plant for genome research. Indeed, it's grain provides human with a source of carbohydrates and proteins. Rice grain has relatively low protein contents (around 8%) compared to other legume seeds (around 40%). Osborne classified seed proteins into water soluble albumin, salt soluble globulin, alcohol soluble prolamin and acidic/alkaline solution soluble glutelin. Glutelin and prolamin are the major storage proteins in rice. For the gene expression study of seed storage proteins, we analyzed 33,192 EST clones at immature stages in a rice cultivar (Oryza sativa L. cv. 'Ilpum'). Based on the expression analysis, we cloned 11 glutelin genes and figured out the 8 genes are located on Chromosome 2. The expression of glutelin genes appears to be about 28.2% of total level in immature seeds. Interestingly, glu-04 is duplicated as inverted sequences on the same chromosomes as far 4.5 kb. Our results indicate that glutelin genes, evolutionarily, were replicated on the chromosome and thus expressed as specific manners. In a whole protein composition analysis, glu05 (type B7) contains the highest lysin contents (4.51%) among the 11 rice glutelin genes. It will be an interesting future work to increase lysin contents by the gene overexpressor strategy with the aim of improved diet nutritionally fortified.

• Journal of Life Science
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• v.17 no.1 s.81
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• pp.82-90
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• 2007

In an attempt to establish the appropriate ventilation device for the bottle culture of king oyster mushroom (Pleurotus eryngii), we investigated carbon dioxide concentration and fruiting body formation according to the various ventilation systems within the mushroom house. In addition to, the efficiency of air circulation and growth rate as well as the appearance of physiologically abnormal phenotypes during their growth stage were also evaluated. four different ventilation devices, parallel-pressure type, positive-pressure type, negative-pressure type, and positive- and negative-pressure type were applied in this study. The positive-and negative-pressure type showed the highest efficiency of air circulation as $CO_2$ concentration was 800 ppm and the level of air current was relatively low compared to the other types (the $CO_2$ concentration of parallel-pressure type was 1,400 ppm). Moreover, the stipe length, the cap diameter, yield, and general quality grown in positive- and negative type ventilation device were also better than in the other three devices though it took slightly longer period for harvesting (18.4 days) than the others (17.6, 17.9 and 18.3 days). The appearance of physiologically abnormal phenotypes such as fruiting body lump, soft rot, and brown rot were significantly decreased in positive-and negative type compared to other types, while the appearance rates were not much different for other symptoms of bacterial ooze, stipe limb and stipe bumpy. In summary, we propose that the optimal ventilation system for the bottle culture of king oyster mushroom is positive- and negative type, and this device is expected to increase the total quality as well as yield all year around.

• Journal of Life Science
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• v.20 no.8
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• pp.1254-1260
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• 2010

Microorganisms near the plant rhizosphere usually inhabit the surface or the inside of the plant roots and have a direct effect on plant growth by secreting plant growth promoters or antagonistic materials which protect the root zone system from various pathogens. This study was carried out to identify and isolate the antagonistic materials after isolation of microorganisms showing high antagonistic activities, in hopes of contributing to the development of sustainable agriculture and the preservation of agricultural environments. A number of antagonistic bacteria were isolated from paddy soil. Among isolates, RRj 228 showed plant growth promotion and antagonistic activity. RRj 228 was identified as Pseudomonas sp. according to the results of physiological properties and genetic methods. On the basis of the results of anti-fungal spectrum against several pathogens by RRj 228, the antagonistic effect of the isolate against Botrytis cinerea, Pythium ultimum, Phytopthola capsici, and Rhizoctonia solani, especially against red-pepper anthracnose caused by Colletotrichum acutatum, was remarkable. The experiment evaluating the biological control effect by RRj 228 revealed that the $ED_{50}$ value by the RRj 228 culture against C. acutatum, R. solani and P. ultimum were 0.14 mg/ml, 0.16 mg/ml and 0.29 mg/ml, respectively. An antagonistic substance was isolated and purified by several chromatographies from the RRj 228 culture. The $^1H$ and $^{13}C$ assignment of the antagonistic substance was achieved from two-dimensional $^1H-^1H$ COSY, HMQC, and HMBC. Finally, the antagonistic substance was identified as Phenazine-1-carboxylic acid ($C_{13}H_8N_2O_2$, M.W.=224).