• KOREAN JOURNAL OF CROP SCIENCE
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• v.32 no.2
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• pp.201-207
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• 1987

This experiment was conducted to identify the superior corn hybrids for silage production and to determine the combining ability of their parental inbred lines. A 7-entry diallel cross was evaluated for grain and stover yields, and agronomic characters under 3 different seasons. Hybrids Hi34 x Tx601, Hi26 x Hi34, and Hi29 x Hi34 showed high total dry matter yields. In general, late maturing hybrids had higher grain and silage yields than early maturing hybrids. Leaf area index was correlated with grain and stover yields. Rust rating was negatively correlated with yields and all characters, indicating that rust (Puccinia sorghi) was one of the major factors affecting yields. Diallel analysis showed that inbred Hi34 which was late in maturity and resistant to rust was the best combiner for both grain and silage yields. General combining ability (GCA) and specific com-bining ability (SCA) effects for yields and other characters were significant, suggesting that both additive and non-additive gene effects are involved for those characters. Ratio of GCA/SCA mean squares showed that GCA effects were more important than SCA effects for yields and other characters. GCA x season and SCA x season interactions were significant for grain and stover yields, revealing that gene effects were not stable for those yields under dissimilar environments.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.60 no.4
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• pp.448-457
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• 2015

Developing rice lines with various amylose contents is necessary to diverse usages of rice in terms of raw materials for processed food production, and thereby to promote rice consumption in Korea. A rice mutant line, 'Namil(SA)-dull1' was established through sodium azide mutagenesis on 'Namil', a non-glutinous Korean Japonica rice cultivar. Namil(SA)-dull1' had dull endosperm characteristics and the evaluated amylose content was 12.2%. A total of 94 F2 progenies from a cross between 'Namil(SA)-dull1' and 'Milyang23', a non-glutinous Tongil-type rice cultivar, was used for genetic studies on the endosperm amylose content. Association analyses, between marker genotypes of 53 SSR anchor markers and evaluated amylose contents of each 94 F2:3 seeds, initially localized rice chromosome 6 as the harboring place for the modified allele(s) directing low amylose content of 'Namil(SA)-dull1'. By increasing SSR marker density on the putative chromosomal region followed by association analyses, the target region was narrowed down 0.94 Mbp segment, expanding from 28.95 Mbp to 29.89 Mbp, on rice chromosome 6 pseudomolecule. Among the SSR loci, RM7555 explained 84.2% of total variation of amylose contents in the $F_2$ population. Further physical mapping on the target region directing low amylose content of 'Namil(SA)-dull1' would increase the breeding efficiency in developing promising rice cultivars with various endosperm characteristics.

• Journal of Food Hygiene and Safety
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• v.35 no.5
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• pp.438-446
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• 2020

Meju and nuruk (respectively soybean and malt) are traditional Korean fermentation starters that are vulnerable to contamination by harmful microorganisms such as aflatoxigenic fungi and their associated aflatoxins (AFs). In this study, Aspergillus spp. were isolated and identified from a total of 57 meju and 18 nuruk samples collected from Korean markets. Their potential aflatoxigenicity was investigated by examining the presence of three aflatoxin biosynthetic genes (aflO, aflP, and aflR) using multiplex polymerase chain reaction (mPCR) assays. Thereafter, aflatoxin production of isolates and the natural occurrence of AFs in meju and nuruk samples were analyzed by high-performance liquid chromatography (HPLC). A total of 177 Aspergillus isolates were identified and 130 isolates were obtained from meju samples. Of these, 25 isolates (19.2%) contained all three aflatoxin biosynthetic genes, and five (20%) of these isolates produced aflatoxins. Forty-seven of the Aspergillus isolates were obtained from nuruk samples, five of which (10.6%) expressed all three AF biosynthetic genes; however, none of these strains produced AFs. HPLC analysis showed that 88% (51/58) of the meju samples and 39% (7/18) of nuruk samples were not contaminated with AFs (below limit of detection). Among the isolates isolated from meju and nuruk, there were aflatoxigenic strains containing all three aflatoxin biosynthetic genes or producing aflatoxin in medium, but the frequency of aflatoxin contamination was low in the meju and nuruk samples.

• Horticultural Science & Technology
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• v.34 no.6
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• pp.818-829
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• 2016

This study evaluated the responses of 18 potato cultivars to three levels of salinity stress (electrical conductivity, EC: 1.0, 4.0, and $8.0dS{\cdot}m^{-1}$). Stem, leaf, root, chlorophyll, tuber yield, and proline content were investigated and statistically analyzed using analysis of variance (ANOVA) and correlations. Stem number and stem diameter were not affected by salinity, but stem length and aerial weight showed highly significant responses to salinity. Aerial weight decreased with increasing salinity levels in most cultivars, while it increased in some the cultivars 'Daejima', 'Goun', 'Haryeong', and 'LT-8'. Leaf number, leaf area index, and leaf weight were most significantly affected by salinity and the cultivar ${\times}$ salinity interaction. Root length, root weight, total chlorophyll and chlorophyll a were affected by salinity, but not by the cultivar ${\times}$ salinity interaction. The opposite trend was shown in chlorophyll b. Although there was great variability among cultivars, tuber yield decreased in all cultivars, and was most significantly influenced by salinity and the cultivar ${\times}$ salinity interaction. 'Superior', 'Kroda', 'Romana', and 'Duback' gave better tuber yields under salinity at EC 4.0 and $8.0dS{\cdot}m^{-1}$ than the cultivars with better aerial weights. Proline content was increased by salinity in all cultivars, and was more remarkable in the cultivars with better aerial weights than in cultivars such as 'Superior' and 'Kroda' with better tuber yields. Leaf number, leaf area index, leaf weight, and root length parameters were considered to be useful criteria in the evaluation of salt tolerance because of their high positive correlation with tuber yield; however, given its negative correlation with tuber yield under high salinity, proline content was not. Salinity tolerances varied greatly among potato cultivars. The low correlation between growth and yields of aerial parts under high salinity suggests that, in commercial agriculture, it might be more practical to compare relative yields to controls. Additionally, 'Superior', 'Kroda', 'Romana', and 'Duback' might be very useful cultivars to use in breeding programs to develop salinity-tolerant potatoes, as well as for sustainable potato production in saline areas.

• Horticultural Science & Technology
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• v.34 no.6
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• pp.871-877
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• 2016

Recycling nutrient solutions in closed hydroponic production systems is usually accompanied by an imbalance of nutrient solutions when concentration is controlled according to electrical conductivity (EC) levels. This study investigated whether it was possible to automatically control the concentrations of five essential elements nitrogen (N), phosphorus (P), potassium (K), calcium (Ca) and magnesium (Mg) using only N, K and Ca ion sensors. N, P, K, Ca, and Mg uptake was measured in the nutrient solution, and relationships between absorbed ions were analyzed through twice-repeated experiments in lettuce. Results confirmed that the pattern of $PO_4$ ion uptake was similar that of N, and the pattern of Mg ion uptake was similar that of Ca. $PO_4$ ion uptake was most highly correlated with N, and Mg was most highly correlated with Ca. Regression coefficients of N and $PO_4$ were significantly different at 1.04 and 0.55, respectively, but were similar between Ca and Mg at 0.35 and 0.40, respectively. Additional experiments were conducted to measure nutrient uptake in pak choi and rose plants, both to confirm the results from the first experiment in lettuce, and to assess possible application to other crops. Coefficients of determination both for N and $PO_4$, and Ca and Mg were considerably high ($R^2=0.86$) in cultured pak choi, and similar results were observed in cultured rose ($R^2=0.87$ and 0.73, respectively). Regression coefficients for cultured pak choi were 0.56 and 0.24, respectively, and for rose were 0.51 and 0.16, respectively. Although the results obtained for N and $PO_4$ were not consistent between the lettuce experiments, N and $PO_4$ have similar regression coefficients for all crops. No common coefficient was found between Ca and Mg.

• Korean Journal of Ecology and Environment
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• v.50 no.1
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• pp.137-147
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• 2017

The identity of toxin producers remains only hypothesis unless there were identified by strain isolation and analytical confirmation of both the cyanotoxin production and the genetic identity of the monoculture. The purposes of this study were to identify a morphologic and phylogenetic classification in Aphanizomenon flos-aquae strains isolated from the Nakdong River and to investigate the potential ability of the strains to produce toxins such as saxitoxin and cylindrospermopsin using target genes. The 16S rRNA and sxtA, sxtI, cyrA, cyrJ genes were analyzed on two strains (DGUC001, DGUC003) isolated from the Nakdong River. Morphological features of the strains were observed a shape of aggregated trichomes in parallel fascicles which can reach up to macroscopic size and a hyaline terminal cell without aerotope. In addition, the 16S rRNA phylogenetic analyses showed that the strains were identified as the same species with high genetic similarity of 98.4% and grouped within a monospecific andsupported cluster I of Aphanizomenon flos-aquae selected from GenBank of the NCBI. The cyrA and cyrJ genes encoding for the cylindrospermopsin-biosynthesis were not detected in the present study. The sxtA gene was in detected both the two strains, whereas the sxtI gene which had been suggested as a suitable molecular marker to detect saxitoxin-producing cyanobacteria was not found both the strains. Thus, the two strains isolated from Nakdong River were identified as the same species of Aphanizomenon flos-aquae Ralfs ex Bornet et Flahault 1888, the two strains were confirmed as potential non-producing strains of the saxitoxin and cylindrospermopsin.

• Journal of Life Science
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• v.15 no.3 s.70
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• pp.415-422
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• 2005

library of the mutants was prepared by transposon mutagenesis of the Mycobacterium bovis BCG. We screened this library for the resistance to an anti-tuberculosis antibiotic, PA-824. Most of the mutants resistant to the PA-824 were not able to synthesize the coenzyme $F_{420}$ which is normally produced by the wild type M. bovis BCG strains. HPLC analysis of the cellular extract showed that one of those mutants which lost the ability to synthesize $F_{420}$ still produced F0. The insertion site of the transposon in this mutant was determined by an inverse PCR and the transposon was found to be inserted in the Rv2435c open reading frame (ORF). Rv2435c ORF is predicted to encode an 80.3 kDa protein. Rv2435c protein appears to be bound to the cytoplasmic membrane, its N-terminal present in the periplasm and C-terminal in the cytoplasm. The C-terminal portion of this protein is highly homologous with the adenylyl cyclases of both prokaryotes and eukaryotes. There are 15 ORFs which have homology with the class III AC proteins in the genome of the M. tuberculosis and M. bovis. Two of those, Rv1625c and Rv2435c, are highly homologous with the mammalian ACs. We cloned the cytoplasmic domain of the Rv2435c ORF and expressed it with six histidine residues attached on its C-terminal in Escherichia coli to find out if this protein is a genuine AC. Production of that protein in E. coli was proved by purifying the histidine-tagged protein by using the Ni-NTA resin. This protein, however, failed to complement the cya mutation in E. coli, indicating that this protein lacks the AC activity. All of the further attempts to convert this protein to a functional AC by a mutagenesis with UV or hydroxylamine, or construction of several different fusion proteins with Rv1625c failed. It is, therefore, possible that Rv2435c protein might affect the conversion of F0 to $F_{420}$ not by synthesizing cAMP but by some other way.

• Korean Journal of Food Science and Technology
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• v.41 no.2
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• pp.173-178
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• 2009

Epidemiological studies showed that high trans-fat consumption is closely associated with getting the risks of cardiovascular disease. The objective of this study was to produce trans-free fat through lipase-catalyzed interesterification, as a substitute for the cream margarine commonly used in industry. Optimum conditions for interesterification in a packed bed enzyme bioreactor (PBEB) were determined using response surface methodology (RSM) based on central composite design. Three kinds of reaction variables were chosen, such as substrate flow rate (0.4-1.2 mL/min), reaction temperature (60-70$^{\circ}C$), and ratio of fully hydrogenated canola oil (FHCO, 35-45%) to evaluate their effects on the degree of interesterification. Optimum conditions from the standpoint of solid fat content (SFC) were found to be as follows: 0.4 mL/min flow rate, 64.7$^{\circ}C$ reaction temperate, and 42.8% (w/w) ratio of FHCO, respectively. The half-life of immobilized lipase in PBEB with two stages at 60$^{\circ}C$ ($1^{st}$ stage) and 55$^{\circ}C$ ($2^{nd}$ stage) was about more than 30 days as estimated by extrapolating the incubation time course of tristearoyl glycerol (TS) conversion, whereas the half-life of the enzyme in PBEB with single stage at 65$^{\circ}C$ was only about 15 days. Finally, the results from SFC analysis suggest that trans-free fat produced in this study seems to be a suitable substitute for the cream margarine commonly used in industry.

• Korean Journal of Food Science and Technology
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• v.42 no.1
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• pp.103-108
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• 2010

To obtain the best yield of the beneficial ingredients in green tea, such as catechins, green tea powder is most often prepared by ethyl alcohol extraction. However, the taste, cost and composition of ethyl alcohol extract is different from aqueous spray-dried green tea extract (aq-GTE). Specifically, aq-GTE has a better flavor, lower production costs and higher purity when compared to ethyl alcohol extract. In this study, we elucidated the effect of aq-GTE on diet-induced obesity in male C57BL/6J mice following dose-dependent oral administration of aq-GTE. After eight weeks, the body weight was reduced by 13-17% in mice fed 200 mg/kg bw aq-GTE ($12.468{\pm}0.45\;g$; p<0.05) and 20-25% in mice fed 400 mg/kg bw aq-GTE ($11.259{\pm}0.61\;g$; p<0.05) when compared with the high-fat diet (HFD) control group mice ($14.714{\pm}0.95\;g$; p<0.05). The correlation between epididymal fat accumulation and body weight also decreased by approximately 26.6% (p<0.05) in mice fed a HFD with aq-GTE 400 mg/kg bw. Finally, serum parameters such as the triglyceride, glucose and cholesterol levels in the HFD groups were reduced by the aq-GTE 400 mg/kg bw diet. Analysis on glutamic-pyruvic transaminase, blood urea nitrogen and development of hepatic steatosis revealed no histologic evidence of hepatotoxicity in HFD mice fed aq-GTE. Overall, our results imply that aq-GTE is able to regulate body weight and fat accumulation in mice.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.5 no.2
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• pp.141-149
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• 2004

The aim of this study was to test the validity of the hypothesis that the karyotypes of four species of Lepilemuridae were formed spontaneously from their ancestral hybrid karyotype. Hypothetical ancestral haploid Karyotype of Lepilemuridae is composed of 18 autosomes and X chromosomes. Lepilemur mustelinus karyotype has four tandem fused chromosomes and one Robertsonian translocated chromosome pairs. Lepilemur septentrionalis septentrionalis karyotype has only two pairs of translocated chromosomes. We reconstruct and suggest ancestral karyotype of LMU(ancLMU) and LSS(ancLSS), from which all four studied species were derived. Hybrids of ancLMU and ancLSS were formed and produce differently fused equilibrated gametes via circular form arrangement during gametogenesis. Five unit of trivalent homologous chromosome pairs were engaged in a circular form to give new gamete corresponding to the karyotype of L. dorsalis, orientation of one unit of trivalent was inversed in the circle to gave new gamete corresponding to the karyotype of L. leucopus. Seven homologous chromosome pairs were engaged in circular form to give haploid karyotype of Lepilemur ruficaudatus. Only one homologous chromosome pair is dissociated and the other chromosome pairs rearranged in the circle to form haploid karyotype of Lepilemur edwardsi. The new gametes could be produced from these circular forms. When the new gamete fertilized with the same type of gamete, The new homozygote is produced as existing L. dorsalis, L. leucopus, L. edwardsi and L. ruficaudatus. These results support the theory that new species could be formed in hybrid population through activated chromosome fusion, chromosome rearrangement in circular from at zygotene stage and production of equilibrated gametes to form homozygote new species.