• Journal of Microbiology and Biotechnology
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• v.18 no.2
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• pp.334-337
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• 2008

A tightly regulated gene expression system composed of a single-copy target gene under the control of a lac promoter derivative and lacI gene in a multicopy plasmid is proposed, and its ability to control the flux of a metabolic pathway is demonstrated. A model system to control the flux of acetyl-CoA to acetyl phosphate was constructed by integrating pta, a gene encoding phosphotransacetylase, under a tac promoter into the chromosome of E. coli with a pta-negative background and transforming a multicopy plasmid containing the $lacI^Q$ gene into the strain. The production rate of acetate was shown to be tightly controlled when varying the concentration of the inducer (IPTG) in he model system.

• Journal of Microbiology and Biotechnology
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• v.8 no.6
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• pp.676-684
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• 1998

Baculovirus transfer and expression vectors with Hyphantria cunea nuclear polyhedrosis virus (HcNPV) were constructed. An initial transfer vector, pHcEV, constructed using HcNPV was previously reported (Park et al. 1993. J. Kor. Soc. Viral. 23: 141-151). Herein, the size of the vector was properly reduced, and a functionally perfect vector was constructed and named pHcEV-IV (6.7 kb). The vector has a 2.2-kb HcNPV DNA sequence in the 5'-flanking region of the vector's polyhedrin gene promoter. The 1.8-kb HcNPV DNA sequence, poly A signal sequence, T3 primer sequence, and 13 multicloning site sequences, in order, were ligated in front of the translation start codon of the polyhedrin gene. The cloning indicating marker lacZ gene was inserted into the pHcEV-IV, named pHcEV-IV-lacZ, and transferred into the wild-type virus. Recombinant expression virus, lacZ-HcNPV, was constructed by replacing the lacZ gene in the pHcEV-IV-lacZ with the polyhedrin gene of the wild-type virus. The recombinant virus was isolated from blue plaques that produce $\beta$-galactosidase without polyhedra. The lacZ gene insertion was confirmed by Southern hybridization analysis. The expression of the lacZ gene in Spodoptera frugiperda cells infected with the lacZ-HcNPV was examined by SDS-PAGE and colorimetric assay. One 116-kDa LacZ protein band appeared on the PAGE. The production rate of the $\beta$-galactosidase was approximately 50 international units (IU) per min per ml between 2 to 5 days postinfection (p.i.). The highest activity occurred at five days p.i. was 170 IU/min/$m\ell$. The enzyme activity first appeared about 20 h p.i. as measured by colorimetric assay.

• Transactions on Electrical and Electronic Materials
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• v.12 no.3
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• pp.93-97
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• 2011

In this paper, we discuss design considerations for an n-channel metal-oxide-semiconductor field-effect transistor (MOSFET) with a lateral asymmetric channel (LAC) doping profile. We employed a 0.35 ${\mu}M$ standard complementary MOSFET process for fabrication of the devices. The gates to the LAC doping overlap lengths were 0.5, 1.0, and 1.5 ${\mu}M$. The drain current ($I_{ON}$), transconductance ($g_m$), substrate current ($I_{SUB}$), drain to source leakage current ($I_{OFF}$), and channel-hot-electron (CHE) reliability characteristics were taken into account for optimum device design. The LAC devices with shorter overlap lengths demonstrated improved $I_{ON}$ and $g_m$ characteristics. On the other hand, the LAC devices with longer overlap lengths demonstrated improved CHE degradation and $I_{OFF}$ characteristics.

• Transactions on Electrical and Electronic Materials
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• v.11 no.1
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• pp.15-19
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• 2010

In this paper, we discuss design considerations for an n-channel metal-oxide-semiconductor field-effect transistor (MOSFET) with a lateral asymmetric channel (LAC) doping profile. We employed a $0.35\;{\mu}m$ standard complementary MOSFET process for fabrication of the devices. The gates to the LAC doping overlap lengths were 0.5, 1.0, and $1.5\;{\mu}m$. The drain current ($I_{ON}$), transconductance ($g_m$), substrate current ($i_{SUB}$), drain to source leakage current ($i_{OFF}$), and channel-hot-electron (CHE) reliability characteristics were taken into account for optimum device design. The LAC devices with shorter overlap lengths demonstrated improved $I_{ON}$ and $g_m$ characteristics. On the other hand, the LAC devices with longer overlap lengths demonstrated improved CHE degradation and $I_{OFF}$ characteristics.

• Journal of Microbiology and Biotechnology
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• v.17 no.12
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• pp.2046-2055
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• 2007

Wild-type V. vulnificus cannot grow using lactose as the sole carbon source or take up the sugar. However, prolonged culture of this species in media containing lactose as the sole carbon source leads to the generation of a spontaneous lactose-utilizing (LU) mutant. This mutant showed strong ${\beta}$-galactosidase activity, whereas the wild-type strain showed a barely detectable level of the activity. A mutant with a lesion in a gene homologous to the lacZ of E. coli in the bacterium no longer showed ${\beta}$-galactosidase activity or generated spontaneous LU mutants, suggesting that the lacZ homolog is responsible for the catabolism of lactose, but the expression of the gene and genes for transport of lactose is tightly regulated. Genetic analysis of spontaneous LU mutants showed that all the mutations occur in a lacI homolog, which is located downstream to the lacZ and putative ABC-type lac permease genes. Consistent with this, a genomic library clone containing the lad gene, when present in trans, made the spontaneous LU mutants no longer able to utilize lactose as the sole carbon source. Taken together with the observation that excessive amounts of exogenously supplemented possible catabolic products of lactose have negative effects on the growth and survivability of V. vulnificus, we suggest that V. vulnificus has evolved to carry a repressor that tightly regulates the expression of lacZ to keep the intracellular toxic catabolic intermediates at a sublethal level.

• Korean Journal of Microbiology
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• v.27 no.3
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• pp.201-209
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• 1989

Using Mu dJ(Km lac) operon fusion, several oxygen-regulated genetic loci were identified in Salmonella typhimurium. Nine aerobically inducible(oxi) and thirteen anaerobically inducible(ani) operon fusions were newly identified. Based on the control by oxrA regulatory locus, the ani-lacZ fusions were grouped into two classes: class I loci were regulated by oxrA regulatory locus; class II genes were not affected by this locus. Some of the ani-lacZ fusions had required growth in CAA and LB before they exhibited the inducible phinotype. Most of all ani-lacZ fusions were repressed by nitrate and fumarate. Three of the ani loci were mapped into $59{\pm}0.14$ map unit (YK114), $64{\pm}0.5$ map unit(YK120), and $93{\pm}0.29$ map unit(YK112) by testing the cotransduction frequency, respectively.

• Asian-Australasian Journal of Animal Sciences
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• v.8 no.5
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• pp.449-454
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• 1995

The present study was conducted to assess gene expression of bacterial lacZ driven by the SV40 promoter at early developmental stages of bovine embryos. The lacZ gene was linearized with BamHI digestion and introduced into the pronucleus by microinjection at 20 hrs after the commencement of in vitro fertilization. Intact bovine blastocysts were not stained with X-Gal, suggesting that there is no endogenous beta-galactosidase activity in these blastocysts. In contrast, the bovine blastocyst cells microinjected with the lacZ gene exerted a characteristic greenish-blue color originating from the bacterial beta-galactosidase activity, albeit at a low rate, i.e. 2.1% of the total fertilized oocytes injected. It was concluded, therefore, that the lacZ gene driven by the SV40 promoter could be used for an indirect screening method in which the presence of transgene is evaluated from the product of transgene expression.

• Applied Biological Chemistry
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• v.38 no.1
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• pp.7-12
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• 1995

The purpose of this study was the development of promoter for the lacZ' gene. Two heterologous promoter I and II of lacZ' gene were isolated from chromosomal DNA Bam HI fragment of yeast. The size of the promoter I was estimated to be 2.5 kb and ${\beta}-galactosidase$ activity was 124.6 U/mg protein, and the size of the promoter II was 4.0 kb and its ${\beta}-galactosidase$ activity was 168.8 U/mg protein, respectively. The stability of the recombinant YEp plasmid in the transformant was from 52.7 to 67.4% at minimal medium. YIp plasmid was constructed from YEp plasmid, and expressed both in E. coli and yeast. The promoter I aid II iso-lated from yeast chromosomal DNA can be used for promoter of plasmid YEp and YIp.

• Environmental Engineering Research
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• v.14 no.1
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• pp.63-67
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• 2009

Escherichia coli K-12 (E. coli K-12) is a representative indicator globally used for distinguishing and monitoring dynamic fates of pathogenic microorganisms in the environment. This study investigated how to most critically quantify lacZ ($\beta$-galactosidase) gene in E. coli K-12 by two different real-time polymerase chain reaction (real-time PCR) in association with three different DNA extraction practices. Three DNA extractions, i.e., sodium dodecyl sulfate (SDS)/proteinase K, magnetic beads and guanidium thiocyanate (GTC)/silica matrix were each compared for extracting total genomic DNA from E. coli K-12. Among them, GTC/silica matrix and magnetic beads beating similarly worked out to have the highest (22-23 ng/${\mu}L$) concentration of DNA extracted, but employing SDS/proteinase K had the lowest (10 ng/${\mu}L$) concentration of DNA retrieved. There were no significant differences in the quantification of the copy numbers of lacZ gene between SYBR Green I qPCR and QProbe-qPCR. However, SYBR Green I qPCR obtained somewhat higher copy number as $1{\times}10^8$ copies. It was decided that GTC/silica matrix extraction or magnetic beads beating in combination with SYBR Green I qPCR can be preferably applied for more effectively quantifying specific gene from a pure culture of microorganism.

• Journal of the Korean Institute of Landscape Architecture
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• v.31 no.4
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• pp.57-66
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• 2003

The purpose of this study is to evaluate the resource value of existing mud flats in JANGWHARI, KANGWHADO, as strategies for ecotourism. The research methods used in this study are Limits of Acceptable Change(LAC), and Recreation Opportunity Spectrum(ROS). The LAC process draws attention to the existing area conditions that are judged to be acceptable. Managers must define desired area conditions and undertake actions to maintain or achieve these conditions. The ROS is within each of the recreation opportunity classes identified as being used at the regional level. The Results of this study are as follows: 1) The Opportunity Class of the ROS is ecological, physical, social, managerial setting as primitive, semi-primitive. non-motorized, semi-primitive$.$motorized, and roaded natural. 2) The indicator of the LAC is ecological, physical, social, and managerial setting; the indicator of ecological is wildlife populations, water quality, road paving; the indicator of physical is facilities; the indicator of social is visitor needs for knowledge, adventure, eco-experience, and environmental education programs; and, the indicator of managerial is limits of law, and degree of management. 3) Currently, the Opportunity Class of the ROS of JANGWHARI, KANGWHADO is levels II-III, and the Opportunity Class of the suggested ROS is levels I-II. 4) This paper describes strategies for mud flat area management: detection of water quality, resolving problems of equipment, supply of both environmental education programs and guide equipment.