• Korean Journal of Fisheries and Aquatic Sciences
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• v.46 no.6
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• pp.901-906
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• 2013

We examined the availability of the lacZ gene (${\beta}$-galactosidase gene) as a reporter of foreign gene transfer in the cysts of Artemia franciscana (A. franciscana) to conduct a risk assessment of living genetically modified organisms (LMOs) in the marine ecosystem. The LacZ gene was transferred to decapsulated cysts by particle bombardment, and its insertion and expression were assessed by means of polymerase chain reaction (PCR) and X-gal staining. X-gal staining indicated lacZ expression in all A. franciscana examined (including the control group), which exhibited not only negative but also positive PCR amplification. Endogenous ${\beta}$-galactosidase is highly active in the whole body of A. franciscana during all stages of the life cycle. Thus, the lacZ gene is unsuitable as a reporter for foreign gene transfer in A. franciscana cysts, because it is difficult to discriminate between exogenous and endogenous ${\beta}$-galactosidase activity.

• Journal of Microbiology and Biotechnology
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• v.31 no.4
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• pp.550-558
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• 2021

Lactobacillus kefiranofaciens contains two types of β-galactosidase, LacLM and LacZ, belonging to different glycoside hydrolase families. The difference in function between them has been unclear so far for practical application. In this study, LacLM and LacZ from L. kefiranofaciens ATCC51647 were cloned into constitutive lactobacillal expression vector pMG36e, respectively. Furtherly, pMG36n-lacs was constructed from pMG36e-lacs by replacing erythromycin with nisin as selective marker for food-grade expressing systems in Lactobacillus plantarum WCFS1, designated recombinant LacLM and LacZ respectively. The results from hydrolysis of o-nitrophenyl-β-galactopyranoside (ONPG) showed that the β-galactosidases activity of the recombinant LacLM and LacZ was 1460% and 670% higher than that of the original L. kefiranofaciens. Moreover, the lactose hydrolytic activity of recombinant LacLM was higher than that of LacZ in milk. Nevertheless, compare to LacZ, in 25% lactose solution the galacto-oligosaccharides (GOS) production of recombinant LacLM was lower. Therefore, two β-galactopyranosides could play different roles in carbohydrate metabolism of L. kefiranofaciens. In addition, the maximal growth rate of two recombinant strains were evaluated with different temperature level and nisin concentration in fermentation assay for practical purpose. The results displayed that 37℃ and 20-40 U/ml nisin were the optimal fermentation conditions for the growth of recombinant β-galactosidase strains. Altogether the food-grade Expression system of recombinant β-galactosidase was feasible for applications in the food and dairy industry.

• Korean Journal of Microbiology
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• v.29 no.4
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• pp.215-220
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• 1991

MudJ(Km.lac) operon fusions were used in the identification of osmotic-inducible genetic(osi) loci in Salmonella typhimurium. Expression of osi::lacZ(osi5001, 5027) genes were dramatically induced 39-189 fold when the osmolarity was increased. Seven osm::lacZ genes were constituvely expressed under both low and high osmotic strength. The osi5001::lacZ fusion strains showed the enhanced osmotolerance and the reduced expression of the osi5001::lacZ in the presence of 1mM proline or betaine as osmoprotectants. Four osmotic inducible genetic loci were mapped into 36 (YK531), 44 (YK504), 57 (YK501) and 84 (YK528) map unit by testing the cotransduction frequency.

• Applied Biological Chemistry
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• v.28 no.1
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• pp.36-47
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• 1985

$HIS_5$ gene of Saccaromyces cerevisiae was cloned into pBR 322 and also into pSH 610 shuttle vector. $HIS_5$ gene was expressed as promoter of lactose operon(lacZ). And $HIS_5-lacZ$ fusion was intergrated into chromosome III of yeast. $HIS_5$ gene in yeast growth was controlled general amino acid control mechanism.

• 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.

• Fisheries and Aquatic Sciences
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• v.7 no.2
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• pp.70-75
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• 2004

The CMV promoter driven lacZ reporter gene (pcDNA-lacZ) was constructed and used for DNA immunization study. The expression of the lacZ gene was confirmed in vitro using RTG-2 cell line before using for in vivo study in olive flounder (Paralichthys olivaceus). In the dose response study, the maximum expression of the lacZ gene was found in the group injected with 5 ${\mu} g$ of the plasmid DNA. Kinetic study showed a significantly increased expression of $\beta-galactosidase$ gene at 7 days after injection. Effects of DNA vaccine on specific and nonspecific immune responses such as antibody and NO production were studied and the significant effect was found in olive flounder injected with 10 and 15 ${\mu} g$ DNA (sub optimal dose for lacZ gene expression). Two pro inflammatory cytokine genes, $IL-l\beta$ and $TNF-\alpha$, were also found to be up regulated in the muscle injected with the plasmid, suggesting an induction of local inflammatory response.

• Korean Journal of Microbiology
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• v.30 no.6
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• pp.460-465
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• 1992

The effect of PSOD expression on lacZ-sodP fusion (pYK4) was explored in Escherichia coli sodA sodB mutants (QC774) under oxidative stress. In this system, although .betha.-galactosidase activity was not fully induced by isopropyl-1-thio-.betha.-galactosidase (IPTG) and was inhibited by glucose, functional PSOD was under lacZ promotor control and was induced by IPTC, lactose, PQ and copper isons, finally, the results show that higher PSOD expression leel was consistently importnat in defending against superoxide radicals.

• BMB Reports
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• v.41 no.8
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• pp.568-574
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• 2008

Antisense RNA molecules are powerful tools for controlling the expression of specific genes but their use in prokaryotes has been limited by their unpredictable antisense effectiveness. Moreover, appreciation of the molecular mechanisms associated with silencing in bacteria is still restricted. Here we report our attempts to define an effective antisense strategy in E. coli, and to dissect the observed silencing process. Antisense constructs complementary to different regions of lacZ were investigated, and silencing was observed exclusively upon expression of antisense RNA hybridising the 5'UTR of lac messenger. The level of lacZ mRNA was reduced upon expression of this antisense construct, and the silencing competence was found to be closely associated with its stability. These observations may help in the design of antisense molecules directed against prokaryotic genes.

• Korean Journal of Animal Reproduction
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• v.19 no.1
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• pp.35-41
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• 1995

In this study, we have tested whether the retrovirus vector system is applicable in transgenic cattle production. To overcome low infectivity of currently available retrovirus vector system we have directly microinjected retrovirus-producing cells into the perivitelline space of the day 1.5 embryos. The virus-producing cell line was designed to release replication-defective retrovirus encapsidated with Gibbon ape leukemia virus (GaLV) envelope protein. E. coli LacZ gene was used as a marker gene to facilitate evaluation of the transgene expression and X-gal staining at morula or blastocyst stage resulted in expression of E. coli LacZ gene The results in these experiments were summarized as follows : 1. The lowest concentration of polybrene necessary for efficient virus infection was Sf' g/ml. 2. Development rate from day 1.5 embryos microinjected with virus-producing cells to the morulae /blastocysts was 29%. 3. 21% of the morulae /blastocysts were LacZ+. 4. There was no evidence that the retrovirus-producing cells used in this study produced replication-competent retrovirus.

• Journal of Applied Biological Chemistry
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• v.53 no.1
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• pp.1-7
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• 2010

xylA promoter is a major promoter in xylose operon of Escherichia coli. xylA promoter is sufficient as the promoter for the construction of new expression vector because this promoter was tightly controlled and induced by the addition of xylose. For the construction of xylose-inducible expression vector, 600 bp of xylA promoter was ligated between AatII and HindIII of pUC18, named pXA600. In order to investigate the effect of XylR protein encoded by xylR gene on the xylA promoter, 1,988 bp of xylR gene including its promoter was ligated into downstream of multiple cloning site to the opposite direction of xylA promoter in pXA600, named pXAR600. For the measurement of expression level, 3,048 bp of lacZ structural gene was fused into xylA promoter in both plasmids pXA600 and pXAR600 as a reporter gene, named pXA600-lacZ and pXAR600-lacZ, respectively. The $\beta$-galactosidase activity of pXA600-lacZ and pXAR600-lacZ in E. coli JM109 was determined to be 1,641 and 2,304 unit by the induction with xylose in LB medium, respectively. The $\beta$-galactosidase activity of pXAR600-lacZ/JM109 was about 1.4 times higher by the induction with xylose than that of pXA600-lacZ/JM109. The $\beta$-galactosidase activity of pXA600-lacZ and pXAR600-lacZ in E.coli JM109 showed 6,282 and 9,320 unit by the induction with xylose in DM minimal medium, respectively. A regulator, xylR protein works as an activator for the gene expression by the addition of xylose in the xylose-inducible vectors because the level of gene expression in pXA600 is increased by the insertion of xylR gene into the same vector. The xynA gene of Streptomyces thermocyaneoviolaceus cloned in pXA600 and pXAR600 was successfully expressed in E. coli BLR(DE3). As a result, plasmids pXA600 and pXAR600 using xylA promoter are sufficient as new expression system to produce a foreign protein in E. coli.