• Journal of the East Asian Society of Dietary Life
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• v.23 no.5
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• pp.546-560
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• 2013

In this study, a natural fermentation starter formulation was developed for manufacturing Korean bread products by substituting baker's yeast with naturally fermented blueberry starters. As the incubation time of the blueberry extracts increased, the pH and total titratable acidity increased. The sweetness (brix%) of blueberry extracts containing various amounts of sugar were higher than the other sample. The result of alcoholicity for naturally fermented blueberry extracts, the fermented blueberry extract containing 20% sugar was highest. Lactic acid bacteria counts increased until the 4th day; however, it decreased from the 5th day, and viable yeast counts increased consistently until the 5th day. The volume for naturally fermented blueberry extracts increased as the incubation time increased. As the fermentation time of blueberry starters increased, the pH of bread dough decreased. The RVA analysis conveyed that wheat flour retrogradation was retarded by increasing the blueberry starter content. The weight of pan breads containing blueberry starters were higher than that of the control, while the volume, specific volume and baking loss rate were lower than those of the control. The moisture content of pan breads containing blueberry starter decreased as storage time increased. In analyzing the visible mold colony during 7 days of storage at $28^{\circ}C$, mold growth in pan breads containing the blueberry starter was retarded. The hardness of breads containing blueberry starters were significantly increased as storage time increased. The breads containing 50% naturally fermented blueberry starter have acceptable sensory properties. In conclusion, these results indicated that 50% of natural fermentation blueberry starter could be very useful as a substitute for yeast when making naturally fermented bread.

• Transactions of the Korean hydrogen and new energy society
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• v.26 no.2
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• pp.164-169
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• 2015

Recent research has focused on alternative fuel to improve engine performance and to comply with emission regulation. Finding an alternative fuel and reducing environment pollution are the main goals for future internal combustion engines. The purpose of this study is to obtain low-emission and high-efficiency by hydrogen enriched CNG fuel in SI engine and is to clarify the effects of hydrogen enrichment in CNG fuelled engine on exhaust emission and performance. An experimental study was carried out to obtain fundamental data for performance and emission characteristics of hydrogen enrichment in SI engine. The experiment was conducted at 2500 rpm, bmep 2 bar, 4 bar conditions while CNG fuel was mixed with 10, 20 and 30% hydrogen blends. From the experimental results, combustion duration was shortened due to rapid flame propagation velocity of hydrogen and these were attributed to the burning velocity increasing exponentially with increasing hydrogen blending ratio. Hydrogen has much wider flammable limit than methane, gasoline and the minimum ignition energy is about an order of magnitude lower than for other combustion. By adding hydrogen, $CO_2$ and HC were reduced. However, $NO_X$ was increased dut to high rate of heat release for hydrogen substitutions.

• Biotechnology and Bioprocess Engineering:BBE
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• v.11 no.3
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• pp.262-267
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• 2006

The objective of this study was to develop new self-organized nanogels as a means of drug delivery in patients with cancer. Pullulan (PUL) and deoxycholic acid (DOCA) were conjugated through an ester linkage between the hydroxyl group in PUL and the carboxyl group in DOCA. Three types of PUL/DOCA conjugates were obtained, differing in the number of DOCA substitutions (DS; 5, 8, or 11) per 100 PUL anhydroglucose units. The physicochemical properties of the resulting nanogels were characterized by dynamic light scattering, transmission electron microscopy, and fluorescence spectroscopy. The mean diameter of DS 11 was the smallest (approx. 100 nm), and the size distribution was unimodal. To determine the organizing behavior of these conjugates, we calculated their critical aggregation concentrations (CACs) in a 0.01-M phosphate buffered saline solution. They were $10.5{\times}10^{-4}mg/mL,\;7.2{\times}10^{-4} mg/mL,\;and\;5.6{\times}10^{-4} mg/mL$ for DS 5, 8, and 11, respectively. This indicates that DOCA can serve as a hydrophobic moiety to create self-organized nanogels. To monitor the drug-releasing behavior of these nanogels, we loaded doxorubicin (DOX) onto the conjugates. The DOX-loading efficiency increased with the degree of DOCA substitution. The release rates of DOX from PUL/DOCA nanogels varied inversely with the DS. We concluded that the PUL/DOCA nanogel has some potential for use as an anticancer drug carrier because of its low CAC and satisfactory drug-loading capacity.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1993.05a
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• pp.134-136
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• 1993

Using the extended H$\ddot{u}$ckel molecular orbital method in connection with the tight binding model, we have studied electronic structure and related properties of superconducting $YBa_2Cu_3O_{7-x}$ crystals in which O-atoms in regular sites were selectively replaced with F atoms. The calculations are based on the crystal structure of Y-Ba-Cu-O obtained by Beno et al.. We use atomic coordinates that refer to the unrelaxed Y-Ba-Cu-O system. In analogy to the isomerism problem with molecules, we discuss all possible combinations of F-substitutions in O-sites with one, two, and four F atoms. The calculations are carried out within charged clusters model for the analogues of the YBa-free copperoxide. Our results suggest that the electronic structure of the symmetrically F-substituted or F-added compound is closer to that of the oxygen-deficient superconducting compound than that obtained from unsymmetrical substitution. This applies in particular if O is replaced with in an O(1) site. This suggests that superconductivity is very sensitive to the oxygen content of the $CuO_2$ layers.

• BMB Reports
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• v.32 no.1
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• pp.20-24
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• 1999

The first step of the branch pathway in tryptophan biosynthesis is catalyzed by anthranilate synthase, which is subjected to feedback inhibition by the end product of the pathway. The $trpE^{FBR}$ gene from a mutant Escherichia coli strain coding for anthranilate synthase that was insensitive to feedback inhibition by tryptophan has been cloned. To identify the amino acid changes involved in the feedback regulation of anthranilate synthase, the nucleotide sequence of the mutant $trpE^{FBR}$ gene was determined. Sequence analysis of the $trpE^{FBR}$ gene revealed that four bases were changed in the structural gene while alteration was not found in the 5' control region. Among these base changes, only two base substitutions caused the alterations in amino acid sequences. From the results of restriction fragment exchange mapping, the 61st nucleotide, C to A substitution, that changed $Pro^{21}{\rightarrow}Ser$ was identified as the cause of the desensitization to feedback inhibition by tryptophan. Additional feedback-resistant enzymes of the E. coli anthranilate synthases were constructed by site-directed mutagenesis to examine the effect of the $Ser^{40}\;{\rightarrow}\;Arg^{40}$ change found in the $trpE^{FBR}$ gene of Brevibacterium lactofermentum. From the feedback inhibition analysis, the $Pro^{21}{\rightarrow}Ser$ and $Ser^{40}{\rightarrow}Arg$ mutants maintained about 50% and 90% of their maximal activities, respectively, even at the extreme concentration of 10 mM tryptophan. From these results, we suggest that the $Pro^{21}$ and $Ser^{40}$ residues are involved in the tryptophan binding in the E. coli enzyme.

• BMB Reports
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• v.42 no.6
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• pp.315-323
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• 2009

In order to elucidate ultimate biological function of the genome, the model animal system carrying mutations is indispensable. Recently, large-scale mutagenesis projects have been launched in various species. Especially, the mouse is considered to be an ideal model to human because it is a mammalian species accompanied with well-established genetic as well as embryonic technologies. In 1990', large-scale mouse mutagenesis projects firstly initiated with a potent chemical mutagen, N-ethyl-N-nitrosourea (ENU) by the phenotype-driven approach or forward genetics. The knockout mouse mutagenesis projects with trapping/conditional mutagenesis have then followed as Phase II since 2006 by the gene-driven approach or reverse genetics. Recently, the next-generation gene targeting system has also become available to the research community, which allows us to establish and analyze mutant mice carrying an allelic series of base substitutions in target genes as another reverse genetics. Overall trends in the large-scale mouse mutagenesis will be reviewed in this article particularly focusing on the new advancement of the next-generation gene targeting system. The drastic expansion of the mutant mouse resources altogether will enhance the systematic understanding of the life. The construction of the mutant mouse resources developed by the forward and reverse genetic mutagenesis is just the beginning of the annotation of mammalian genome. They provide basic infrastructure to understand the molecular mechanism of the gene and genome and will contribute to not only basic researches but also applied sciences such as human disease modelling, genomic medicine and personalized medicine.

• Molecules and Cells
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• v.27 no.3
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• pp.365-381
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• 2009

The chloroplast DNA sequences of Megaleranthis saniculifolia, an endemic and monotypic endangered plant species, were completed in this study (GenBank FJ597983). The genome is 159,924 bp in length. It harbors a pair of IR regions consisting of 26,608 bp each. The lengths of the LSC and SSC regions are 88,326 bp and 18,382 bp, respectively. The structural organizations, gene and intron contents, gene orders, AT contents, codon usages, and transcription units of the Megaleranthis chloroplast genome are similar to those of typical land plant cp DNAs. However, the detailed features of Megaleranthis chloroplast genomes are substantially different from that of Ranunculus, which belongs to the same family, the Ranunculaceae. First, the Megaleranthis cp DNA was 4,797 bp longer than that of Ranunculus due to an expanded IR region into the SSC region and duplicated sequence elements in several spacer regions of the Megaleranthis cp genome. Second, the chloroplast genomes of Megaleranthis and Ranunculus evidence 5.6% sequence divergence in the coding regions, 8.9% sequence divergence in the intron regions, and 18.7% sequence divergence in the intergenic spacer regions, respectively. In both the coding and noncoding regions, average nucleotide substitution rates differed markedly, depending on the genome position. Our data strongly implicate the positional effects of the evolutionary modes of chloroplast genes. The genes evidencing higher levels of base substitutions also have higher incidences of indel mutations and low Ka/Ks ratios. A total of 54 simple sequence repeat loci were identified from the Megaleranthis cp genome. The existence of rich cp SSR loci in the Megaleranthis cp genome provides a rare opportunity to study the population genetic structures of this endangered species. Our phylogenetic trees based on the two independent markers, the nuclear ITS and chloroplast MatK sequences, strongly support the inclusion of the Megaleranthis to the Trollius. Therefore, our molecular trees support Ohwi's original treatment of Megaleranthis saniculifolia to Trollius chosenensis Ohwi.

• Fisheries and Aquatic Sciences
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• v.18 no.1
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• pp.99-107
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• 2015

A natural hybrid of a probable intergeneric mating between the striped shiner Pungtungia herzi and the stone morocco Pseudorasbora parva (Cypriniformes: Cyprinidae) was captured in the Geumho River, a tributary of the Nakdong River basin in Korea. Morphological characters and DNA sequences were analyzed to verify its hybrid state and identify the parentage of its parent species. The hybrid exhibited a phenotypic intermediacy between the two parent species in the number of vertebrae and the mouth shape. Out of 1,488 base pair (bp) positions of the nuclear recombination activating gene 1 gene (rag1), which has a biparental mode of inheritance, 41-bp substitutions were detected between the two parent species, whereas an electropherogram of the hybrid displayed polymorphic double peaks at all of the base positions, along with one additional one, strongly indicating its hybrid state. Meanwhile, sequence comparison of the mitochondrial cytochrome b gene (mt-cyb) (1,140 bp), which has a maternal mode of inheritance, showed only 5-22-bp differences (97.6-99.5% identities) between the hybrid and Pu. herzi, but as many as 158-168-bp differences (85.2-86.1% identities) between the hybrid and Ps. parva, clearly indicating Pu. herzi as the maternal species. Thus, combined analyses of independent data sets (i.e., morphology and nuclear and mitochondrial DNA sequences) offered convincing evidence for the hybrid state of a naturally occurring hybrid resulting from intergeneric mating between a female Pu. herzi and a male Ps. parva.

• Parasites, Hosts and Diseases
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• v.42 no.2
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• pp.61-66
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• 2004

The plasmepsins are the aspartic proteases of malaria parasites. Treatment of aspartic protease inhibitor inhibits hemoglobin hydrolysis and blocks the parasite development in vitro suggesting that these proteases might be exploited their potentials as antimalarial drug targets. In this study, we determined the genetic variations of the aspartic proteases of Plasmodium vivax (PvPMs) of wild isolates. Two plasmepsins (PvPM4 and PvPM5) were cloned and sequenced from 20 P. vivax Korean isolates and two imported isolates. The sequences of the enzymes were highly conserved except a small number of amino acid substitutions did not modify key residues for the function or the structure of the enzymes. The high sequence conservations between the plasmepsins from the isolates support the notion that the enzymes could be reliable targets for new antimalarial chemotherapeutics.

• Korean Journal of Poultry Science
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• v.39 no.4
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• pp.311-315
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• 2012

The increasing demand for Korean native chicken meat indicates that the discovery of haplotypes is very important from both economic and conservation points of view. In this study, mtDNA D-loop sequences from two crossbred Korean native chicken populations of 138 individuals were investigated. Twenty six nucleotide substitutions were identified from sequence analysis and were classified into 12 haplotypes. The haplotype H_8 represents 73.47% of Woorimatdag (chicken population) sequences, which were identified in all five Woorimatdag chicken populations investigated. The H_7 haplotype (Dhap1) for D population covers 45% sequences, which indicate maternal inheritance from black Korean native chicken. On the other hand, Chap3 and Chap4 for C population are specific haplotypes, as H_5 and H_2, respectively. Based on the network profiles, six SNPs (C199T, A239G, G242A, A291G, T330C and C391A) of the D-loop region are effective markers for discrimination between Woorimatdag and Hanhyup chicken populations. Also, the phylogenetic analyses of Woorimatdag and Hanhyup chicken populations were used to identify the genetic relationships among the haplotypes. The results presented here can be used for developing molecular markers to discriminate between two commercial Korean native chickens.