• Journal of Microbiology and Biotechnology
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• 제16권11호
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• pp.1799-1808
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• 2006

A food-grade integration vector based on site-specific recombination was constructed. The 5.7-kb vector, pIMA20, contained an integrase gene and a phage attachment site originating from bacteriophage A2, with the ${\alpha}$-galactosidase gene from Lactobacillus plantarum KCTC 3104 as a selection marker. pIMA20 was also equipped with a controllable promoter of nisA ($P_{nisA}$) and a signal peptide-encoding sequence of usp45 ($SP_{usp45}$) for the production and secretion of foreign proteins. pIMA20 and its derivatives mediated site-specific integration into the attB-like site on the Lactococcus lactis NZ9800 chromosome. The vector-integrated recombinant lactococci were easily detected by the appearance of blue colonies on a medium containing $X-{\alpha}-gal$ and also by their ability to grow on a medium containing melibiose as the sole carbon source. Recombinant lactococci maintained these traits in the absence of selection pressure during 100 generations. The ${\alpha}-amylase$ gene from Bacillus licheniformis, lacking a signal peptide-encoding. sequence, was inserted downstream of $P_{nisA}\;and\;SP_{usp45}$ in pIMA20, and the plasmid was integrated into the L. lactis chromosome. ${\alpha}-Amylase$ was successfully produced and secreted by the recombinant L. lactis, controlled by the addition and concentration of nisin.

• Asian-Australasian Journal of Animal Sciences
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• 제15권7호
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• pp.992-997
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• 2002

Two in vivo experiments were conducted to evaluate the effect of novel urease inhibitor hydroquinone (HQ) on ammonia release rate from urea hydrolysis, nitrogen balance, nutrient digestibility and efficiency of microbial protein synthesis. In Exp. 1, twelve crossbred cannulated lambs were randomly assigned within initial body weight block to one of four HQ treatments, which included 0 (control), 30, 60 or 80 mg HQ/kg DM intake. Ammonia concentration and pH of ruminal fluid were immediately measured at 0, 2, 4, 6 and 8 h after feeding. Increasing the dose of HQ tended (p<0.15) to linearly decrease NH3 formation. The ammonia peak concentration (2 h post-feeding) in animals receiving HQ was approximately one-half of that in animals not receiving HQ (p<0.01), and a relatively sustained ammonia release could be obtained at the dose of 30 or 60 mg HQ/kg DM. In Exp. 2, sixteen intact crossbred lambs (weight $40{\pm}0.8kg$) were used in a $2{\times}2$ factorial design experiment. The four rations consisting of soybean meal-based (SBM) or urea-based (Urea) nitrogen source with or without HQ (S1, S0, U1 and U0) were fed in digestion and N balance trials. Apparent digestibility of major nutrients except that of ADF was not affected by either nitrogen source or addition of HQ. Regardless of nitrogen source, supplementation of HQ significantly improved ADF digestibility (p<0.05). The various ration had no effects on N metabolism in the presence of HQ. There was significant difference between total purine derivatives (PD), estimated efficiency of microbial N synthesis (p<0.05) and urea-N excretion (p<0.01) in the urine for the SBM ration and for the Urea ration. However, HQ had little influence on efficiency of microbial N synthesis as proportion of daily intake of total tract digestible OM (p>0.05). No interactions between main nitrogen source and HQ were measured throughout the trial. Results of this study suggest that addition of HQ to ration may improve ADF digestion with having no negative effect on N metabolism and microbial protein production.

• 대한화학회지
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• 제35권6호
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• pp.667-672
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• 1991

팔라듐(Ⅱ) 이온의 존재하에서 isonitrosobenzoylacetone(IBA)과 diamine (ethylenediamine(en) 또는 trimethylenediamine(tn))으로부터 새로운 착물들인 N-(2-aminoethylisonitrosobenzoylacetone imino) chloropalladium(Ⅱ), PdCl(IBA)-en, 및 N-(3-aminopropylisonitrosobenzoylacetone imino) chloropalladium(Ⅱ), PdCl (IBA)-tn을 합성하고 이들 착물의 구조를 조사하였다. 그 결과 이들 착물은 모두 사각평면구조를 가지며 하나의 디이민리간드와 염소이온이 금속에 배위되어 있음을 알 수 있었다. 여기서 디이민리간드는 isonitrosobenzoylacetone과 diamine이 1:1로 반응하여 생성되었으며, isonitroso (=N-O), C=N 및 $NH_2$기의 세개의 질소원자들을 통하여 금속에 결합하고 있는 세자리 리간드임을 알 수 있었다.

• Molecular & Cellular Toxicology
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• 제5권3호
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• pp.216-221
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• 2009

Bisphenol A (BPA) is commonly used in the production of pharmaceutical, industrial, and housing epoxy, as well as polycarbonate plastics. Owing to its extensive use, BPA can contaminate the environment either directly or through derivatives of these products. BPA has been classified as an endocrine disruptor chemicals (EDCs), and the primary toxicity of these EDCs in males involves the induction of reproductive system abnormality. First, in order to evaluate the direct effects on the Y chromosome associated with reproduction, we evaluated Y chromosome abnormalities using a Y chromosome microdeletion detection kit. However, we detected no Yq abnormality as the result of BPA exposure. Secondly, we performed high-density oligonucleotide array-based comparative genome hybridization (CGH) to assess genomic alteration as a component of our toxicity assessment. The results of our data analysis revealed some changes in copy number. Seven observed features were gains or losses in chromosomal DNA (P-value<1.0e-5, average log2 ratio>0.2). Interestingly, 21 probes of chr7:7312289-10272836 (qA1-qA2 in cytoband) were a commonly observed amplification (P-value 3.69e-10). Another region, chr14:4551029-10397399, was also commonly amplified (P-value 2.93e-12, average of log2 ratios in segment>0.3786). These regions include many genes associated with pheromone response, transcription, and signal transduction using ArrayToKegg software. These results help us to understand the molecular mechanisms underlying the reproductive effects induced by BPA.

• 대한화학회지
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• 제22권1호
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• pp.30-36
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• 1978

25% dioxane 수용액 속에서 ${\alpha}$-nitrobenzaldehydephenylhydrazone의 여러 유도체(p-N$NO_2$,p-Cl, m-$NO_2$, p-$CH_3$)에 대해 pH의 변화에 따르는 가수분해 속도상수를 $25^{\circ}C$에서 자외선 분광광도법으로 측정하여 넓은 pH에서 잘 맞는 반응 속도식을 구하였다. 가수분해 속도에 미치는 치환기효과를 고려하고자 Hammett의 식을 적용한 결과 pH1.0에서는 ${\rho}$=0.18, pH 7.0에서는 ${\rho}$=0.06을 얻었다. pH의 변화에 따르는 반응속도상수의 변화, 용매효과, 치환기효과, 산해리상수 측정 등으로부터 ${\alpha}$-nitrobenzaldehydephenylhydrazone의 가수분해는 pH 3.0 이하에서는 $S_N1$, pH 4.0 이상에서는 1,3-dipole을 거치는 반응이 pH 3.0 과 pH 4.0 사이에서는 이 두 반응이 경쟁적으로 일어남을 알았다.

• BMB Reports
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• 제29권4호
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• pp.277-285
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• 1996

In Pseudomonas fluorescens grown on malonate as sole carbon source, acetyl-CoA synthetase was induced, suggesting that malonate is metabolized through acetate and then acetyl-CoA. Acetyl-CoA synthetase was purified 18.6-fold in 4 steps to apparent homogeneity. The native molecular mass of the enzyme estimated by a native acrylamide gel electrophoresis was 130 kDa. The enzyme was composed of two identical subunits with a molecular mass of 67 kDa. Optimum pH was 70. The acetyl-CoA synthetase showed typical Michaelis-Menten kinetics for the substrates, acetate, ATP and CoA, whose $K_m$ values were calculated to be 33.4, 74.8, and 40.7 mM respectively. Propionate. butyrate and pentanoate were also used as substrates by the enzyme, but the rate of the formation of the CoA derivatives was decreased in the order of the increase in carbon number. The enzyme was inhibited by the group-specific reagents diethylpyro-carbonate, 2,3-butanedione, pyridoxal-5'-phosphate and N-bromosuccinimide. In the presence of substrates the inactivation rate of the enzyme, by all of the group-specific reagents mentioned above decreased, indicating the presence of catalytically essential histidine, arginine, lysine and tryptophan residues at or near the active site. Preincubation of the enzyme with ATP, $Mg^{2+}$ resulted in the increase of its susceptibility to diethylpyrocarbonate, suggesting that ATP, $Mg^{2+}$ may induce a conformational change in the active site exposing the essential histidine residue to diethylpyrocarbonate. The enzyme was acetylated in the presence of acetyl-CoA, indicating that this is one of acyl-enzyme.

• Journal of Microbiology and Biotechnology
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• 제28권7호
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• pp.1078-1085
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• 2018

A salt-tolerant cellulase secreted by a marine Bacillus sp. SR22 strain with wide resistance to temperature and pH was purified and characterized. Its approximate mass was 37 kDa. The endoglucanase, named as Bc22Cel, was purified by ammonium sulfate precipitation, gel filtration chromatography, and extraction from the gel after non-reducing sodium dodecyl sufate-polyacrylamide gel electrophoresis. The optimal pH value and temperature of Bc22Cel were 6.5 and $60^{\circ}C$, respectively. The purified Bc22Cel showed a considerable halophilic property, being able to maintain more than 70% of residual activity even when pre-incubated with 1.5 M NaCl for 1 h. Kinetic analysis of the purified enzyme showed the $K_m$ and $V_{max}$ to be 0.704 mg/ml and $29.85{\mu}mol{\cdot}ml^{-1}{\cdot}min^{-1}$, respectively. Taken together, the present data indicate Bc22Cel as a potential and useful candidate for industrial applications, such as the bioconversion of sugarcane bagasse to its derivatives.

• 농약과학회지
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• 제11권1호
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• pp.1-7
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• 2007

살균활성을 보이는 천연물인 incrustoporin(1)의 기본골격인 2(5H)-furanone을 포함하는 유도체 2를 microwave를 이용한 Suzuki-Miyaura coupling 반응으로 합성하였고, 또한 furanone의 화학구조에서 산소원자를 탄소원자로 치환한 2-cycloalkenone 유도체 3 및 4를 유사한 방법으로 합성하였다. 합성한 이들 유도체들의 살균활성을 6종의 식물병원균에 대하여 조사한 결과, 벼 도열병 및 토마토 역병에 대하여 다소 방제효과를 나타내었다. 따라서 이들 유도체들은 다양한 구조변화를 통한 살균제 개발에 활용할 수 있을 것으로 생각된다.

• 대한수학교육학회지:학교수학
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• 제11권3호
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• pp.527-546
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• 2009

본 연구는 CAS가 도입된 이후의 우리나라 수학교육에 대비하여 고등학교 수학활동에서 CAS의 도구발생 과정을 통찰하고, 중등수학교육에서 도구화된 CAS의 활용 가능성을 탐색하기 위해 설계되었다. 이를 위하여 본 연구자는 CAS에 기반 한 개념중심 수학과제 학습과 문제해결을 각각 고안하였으며 고등학교 1학년생 7명을 대상으로 총 12차시의 수업을 실시하고 수업녹화자료와 면담을 통해 학생들의 활동을 분석하였다. 분석결과 학생들은 CAS를 이용하여 수준 높은 응용문제를 다룰 수 있는 것으로 나타나 CAS가 교육과정 내용수준에 영향을 줄 수 있음을 확인할 수 있었고, 또 도구화된 CAS에 기반 한 무리방정식 문제해결활동을 통해 CAS가 교육과정의 제시 순서에 영향을 줄 수 있음을 발견하였다. 이 연구는 고등학교 수학교육에서 CAS의 도구발생을 분석하여 사례를 제공함으로써 CAS가 도입된 이후의 우리나라 수학교육에 대비한 기초연구가 될 것이다.

• 대한미생물학회지
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• 제21권1호
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• pp.33-45
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• 1986

On hundred and forty stains of shigella cultures isolated from the twelve hygiene laboratories of cities and provincial general hospital laboratories in 1983 were tested for their resistance to thirteen antimicrobial drugs and their R-plasmid transfer. Antimicrobial drugs were used amikacin, ampicillin, cephalothin, chloramphenicol, gentamicin, kanamycin, nalidixic acid, rifampicin, streptamycin, tetracycline, tobramycin, cefoperazone and piperacillin. All strains were resistant to one or more of thirteen antimicrobial drugs but 94.3% were susceptible to amikacin, gentamicin and tobramycin of total isolated. The most strains commonly found resistance was to chloramphenicol (94%) followed by streptamycin (93%), tetracyline (92%) piperacillin (90%) ampicillin (83%), cefoperazone (42%), nalidixic acid (14%), cephalothin (17%), rifampicin (22%) and kanamycin (6%), sixty percent of strains among 140 were resistance to ampicillin, chloramphenicol, streptomycin, tetracycline at the same time. The transfer of drug resistance by conjugation was tested and ninety four strains (94.3%) were resistant to one or more drugs were found to transfer their drug resistance of E. coli. percentage of transfer frequency by conjugation was one strains (54%), the transfer frequency of drug resistance varied by donor strains and recipients, but not by selecting drugs. Resistance to nalidixic acid was not transferred by conjugation to recipients. Percentage of plasmid curing after the treatment of acriflavine, acridine orange was about 8%. Among strains cured two strains were tested compare original strains with them in biochemical properties in arginine dihydrolase and arabinose fermentation reaction. It was found to growth curves of No.2 shigella flexneri, serotype 1b, and its derivatives cured with acriflavine in $M{\ddot{u}}ller$ Hinton broth medium (pH 7.4, $38^{\circ}C$) by temperature Gradient Biophoto Recorder TN-1120 (Tokyo, Japan).