• Toxicological Research
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• v.17
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• pp.319-321
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• 2001

Taihu Lake is a major water source for part of Yangtze Delta, which is one of the most urbanized and economically prosperous areas in China. In last couple of decades, some parts of the lake were highly polluted due to eutrophication. This study analyzed dioxin-like potential and mutagenic potential in surface water samples from Taihu Lake. The samples were prepared by XAD-2 resin procedure. A batch of biological assays, including dioxin-like potential microassay with the rat hepatocyte cell line H411E, and Ames test was employed in the research. Results showed that jour water samples have high content of dioxin-like biological potential, the highest activity TEQ to 2,3,7,8-TCDD was 48 pg/ι in sample 1. The mutagenic effect with reading-frame shifting mechanism was confirmed in 3 of 4 samples. The effective sewage treatment facilities and reliable monitoring surveillance system are urgently needed for this area.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.50 no.4
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• pp.286-290
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• 2005

Ascorbate peroxidase (APX) plays a crucial role in the detoxification of hydrogen peroxide. APX activity is maintained significantly higher in the paraquat­treated leaves of the paraquat-tolerant Rehmannia glutinos. This study was conducted to understand structural and regulatory characteristics of APX gene in R. glutinosa. A putative APX cDNA clone (RgAPX1) was isolated from a leaf cDNA library using a partially sequenced expressed sequence tag clone. RgAPX1 is consisted of 1148 bp nucleotides and contains an open reading frame encoding a 250 amino acid-long polypeptide. Deduced RgAPX1 amino acid sequence shares higher sequence similarity to cytosolic APXs. RgAPX1. expression was higher in the leaf than in the flower and root. Southern blot result indicates the presence of one or two RgAPX1-related genes in R. glutinosa genome. RgAPX1 transcription was affected differentially by various stresses and phytohormone. The results indicate that RgAPXl is constitutively expressed in most tissues and its expression is modulated for the immediate and efficient detoxification of $H_2O_2$ under normal and stress conditions.

• Journal of Microbiology and Biotechnology
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• v.10 no.4
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• pp.559-563
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• 2000

A dextransucrase gene (dsrB742) that expresses a dextransucrase to synthesize mostly ${\alpha}-1{\rightarrow}6$ linked dextran with a low amount (3-5%) of ${\alpha}-1{\rightarrow}3$ branching was cloned and sequenced from Leuconostoc mesenteroides B-742CB. The 6.1-kb PstI fragments were ligated with pGEM-3Zf(-) and transformed into E. coli $DH5{\alpha}$. The recombinant clone (pDSRB742) synthesized dextran on an agar plate containing 2% (w/v) sucrose. The dextran synthesized was hydrolyzed with Penicillium endo-dextranase. The hydrolyzate was composed of glucose, isomaltose, isomaltotriose, and branced pentasaccharide. The nucleotide sequence of dsrB742 showed one open reading frame (ORF) composed of 4,524 bp encoding dextrasnsucrase. The deduced amino acid sequence revealed a calculated molecular mass of 168.6 kDa. It also showed an activity band of 184 kKa on a non-denaturing SDS-PAGE (10%). The amino acid sequence of DSRB742 exhibited a 50% similarity with DSRA from L. mesenteroides B-1299, a 70% similarity with DSRS from L. mesenteroides B-512 (F, FMCM) and a 45-56% similarity with Streptococcal GTFs.

• Journal of Microbiology and Biotechnology
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• v.17 no.1
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• pp.29-36
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• 2007

The xynA gene encoding the xylanase A of Paenibacillus sp. DG-22 was isolated with a DNA probe obtained by PCR amplification, using degenerated primers deduced from the amino acid residues of the known N-terminal region of the purified enzyme and the conserved region in the family 11 xylanases. The positive clones were screened on the LB agar plates supplemented with xylan, by the Congo-red staining method. The xynA gene consists of a 630-bp open reading frame encoding a protein of 210 amino acids, and the XynA preprotein contains a 28-residues signal peptide whose cleavage yields a l82-residues mature protein of a calculated molecular weight of 20,000Da and pI value of 8.77. The cloned DNA fragment also has another ORF of 873 nucleotides that showed 76% identity to the putative transcriptional activator of Bacillus halodurans C-125. Most of the xylanase activity was found in the periplasmic space of E. coli. The xynA gene was subcloned into pQE60 expression vector to fuse with six histidine-tag. The recombinant xylanase A was purified by heating and immobilized metal affinity chromatography. The optimum pH and temperature of the purified enzyme were 6.0 and $60^{\circ}C$, respectively. This histidine-tagged xylanase A was less thermostable than the native enzyme.

• Journal of Microbiology and Biotechnology
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• v.15 no.5
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• pp.1067-1072
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• 2005

A metagenomic library was constructed using a fosmid vector, and total genomic DNA was extracted directly from soil at Cisolok (hot spring area, Indonesia). This library was composed of 10,214 clones and screened for lipolytic enzyme on tributyrin agar plates. An esterase gene (estMa) was subcloned and sequenced from a positive lipolytic active clone. Esterase EstMa was encoded by a 954-bp open reading frame and showed low ($11-33\%$) amino acid similarity to known esterases. The amino acid sequence analysis demonstrated that the enzyme is a new member of lipolytic enzyme family VI. The estMa gene encodes a preprotein of 317 amino acids with a predicted molecular mass of 34,799 Da. The purified enzyme exhibited optimal activity at $50^{\circ}C$ and pH 6.5. The $K_m,\;and\;V_{max}$ values of EstMa for the hydrolysis of p-nitrophenyl valerate were $45.3\;{\mu}M$ and 4.45 U/mg, respectively.

• Journal of Microbiology and Biotechnology
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• v.13 no.1
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• pp.139-145
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• 2003

The gene encoding Thermus caldophilus GK24 polyphosphate kinase (Tca PPK) was cloned and sequenced. The gene contains an open reading frame encoding 608 amino acids with a calculated molecular mass of 69,850 Da. The deduced amino acid sequence of Tca PPK showed a 40% homology to Escherichia coli PPK, and $39\%$ to Klebsiella aerogenes PPK. The Tca ppk gene was expressed under the control of the T7lac promoter on pET-22b(+) in E. coli and its enzyme was purified about 70-fold with $36\%$ yield, following heating and HiTrap chelating HP column chromatography. The native enzyme was found to have an approximate molecular mass of 580,000 Da and consisted of eight subunits. The optimum pH and temperature of the enzyme were 5.5 and $70^{\circ}C$, respectively. A divalent cation was required for the enzyme activity, with $Mg^2+$ being the most effective.

• Journal of Microbiology and Biotechnology
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• v.8 no.1
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• pp.14-20
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• 1998

Syntheses of the B. stearothermophilus xylanolytic enzymes such as xylanases, ${\beta}$-xylosidases, ${\alpha}$-arabinofurano-sidases, and esterases, were observed to be regulated by the carbon source present in the culture media. Xylan induced synthesis of ${\beta}$-xylosidase at the highest level while xylose gave about 30% of the ${\beta}$-xylosidase activity induced by xylan. The lowest syntheses of the xylanolytic enzymes above mentioned were detected in the basal medium containing glucose as a sole carbon source. When a mixture of xylan and glucose was used as a carbon source, we could observe glucose repression of xylanase (about 70-fold) and ${\beta}$-xylosidase (about 40-fold) syntheses. Whereas, the level of the glucose repression of the expression of the xylA gene encoding the major ${\beta}$-xylosidase of B. stearothermophilus was assessed to be about l0-fold when the relative amounts of the xylA transcript were determined. From the sequence of the xylA gene, we could find two CRE-like sequences (CRE-l: nucleotides ＋124 to ＋136 and CRE-2:＋247 to ＋259) within the reading frame of the xylA gene, either or both of which were suspected to be involved in catabolite repression of the xylA gene.

• Journal of Microbiology and Biotechnology
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• v.8 no.1
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• pp.21-27
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• 1998

The xylA gene of Bacillus stearothermophilus encoding the major ${\beta}$-xylosidase was previously cloned and sequenced. In the present study we examined the regulation of the cloned xylA gene expression in Bauillus subtilis MW15 carrying the xylA::aprA fusion plasmids. The induction of the fused xylA gene expression remained uninfluenced by any of the carbon sources tested but the gene expression was repressed about 2-3 fold in the presence of glucose. Two CRE-like sequences (CRE-1: nucleotides ＋ 124 to ＋136 and CRE-2: ＋247 to ＋259) were recognized within the reading frame region of the xylA gene. The deletion experiments showed that the CRE-2 sequence had a role in catabolite repression (CR) as a true CRE of the xylA gene, but the CRE-1 had no effect on CR of the xylA gene expression. Surprisingly, the deletion of the CRE- 1 sequence reduced about 2~3 fold of the expression of the xylA fused gene. The repression ratios of the xylA gene expression were estimated to be about 0.4 from the assay of subtilisin activity, and about 0.3 at the level of transcription by determining the amounts of xylA transcripts in B. subtilis. While, the level of CR of the xylA gene was assessed to be about l0-fold in previous work when the relative amounts of the xylA transcripts were measured in B. stearothermophilus.

• 한국디지털정책학회:학술대회논문집
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• 2004.05a
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• pp.675-690
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• 2004

A new way of teaching on the Internet can be called Web Based Instruction (WBI). WBI goes far above and beyond teaching in the school. It will have an impact on overall educational activity that will dramatically change many existing educational processes and persuade most teachers to change their conventional teaching methods. The main purposes of this research were to make a comparative study of academic achievement between expository lecture and web-based instruction, and to identify the difference in academic achievement of learning tasks in pre- and post- experiments of WBI. The conclusions of this study were as follows. First. there are no differences in academic achievement between expository lecture and teacher- directed web based instruction. Second, there are no differences in academic achievement between expository lecture and teacher-assisted web based instruction. Third, there is difference in academic achievement between teacher-assisted web based instruction and teacher-directed web based instruction. Fourth, there are no differences in academic achievement of reading tasks in pre- or post- experiments of teacher-directed web based instruction. On the basis of the research results and discussion, we finally present a Web-Application-Model (WAM) to encourage the usage of Internet as a useful teaching channel.

• Korean Journal of Agricultural Science
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• v.37 no.3
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• pp.367-371
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• 2010

Farnesyl diphosphate synthase (FPS) catalyzes the biosynthesis of farnesyl diphosphate, a precursor for many important terpenoid products. A cDNA encoding FPS was first isolated from Allium sativum (AsFPS) using rapid amplification of cDNA ends (RACE) PCR. The sequence of AsFPS contains an open reading frame encoding a protein of 341 amino acids with a predicted molecular mass of 39.61 kDa. Alignment of AsFPS deduced amino acid revealed high identities with other plants ranging from 79% to 85% and showed 2-high conserved aspartate-rich motifs known to be important for FPS activity. Furthermore, AsFPS expression was stronger in the green organs such as bulbils, scapes, leaves, stems, but weaker in bulbs and roots than on-green organs of A. sativum.