• Journal of Microbiology and Biotechnology
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• v.18 no.4
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• pp.639-647
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• 2008

The heat-inducible expression vectors for Corynebacterium glutamicum and C. ammoniagenes were constructed by using the ${\lambda}O_L1$ and the cryptic promoters, CJ1 and CJ4 that express genes constitutively in C. ammoniagenes. Although the promoters were isolated from C. ammoniagenes, CJ1 and CJ4 were also active in C. glutamicum. To construct vectors, the $O_L1$ from the ${\lambda}P_L$ promoter was isolated and fused to the CJ1 and CJ4 promoters by recombinant PCR. The resulting artificial promoters, CJ1O and CJ4O, which have one ${\lambda}O_L1$, and CJ1OX2, which has two successive ${\lambda}O_L1$, were fused to the green fluorescent protein (GFP) gene followed by subcloning into pCES208. The expression of GFP in the corynebacteria harboring the vectors was regulated successfully by the temperature-sensitive cI857 repressor. Among them, C. ammoniagenes harboring plasmid pCJ1OX2G containing GFP fused to CJ1OX2 showed more GFP than the other ones and the expression was tightly regulated by the repressor. To construct the generally applicable expression vector using the plasmid pCJ1OX2G, the His-tag, enterokinase (EK) moiety, and the MCS were inserted in front of the GFP gene. Using the vector, the expression of pyrR from C. glutamicum was tried by temperature shift-up. The results indicated that the constructed vectors (pCeHEMG) can be successfully used in the expression and regulation of foreign genes in corynebacteria.

• Proceedings of the Korean Society of Toxicology Conference
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• 2000.11a
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• pp.45-67
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• 2000

2-Amino-3,8-dimethylimidazo[4,5-f]quinoxaline (MeIQx) is a mutagenic and carcinogenic heterocyclic amino found in cooked meat. The in vivo mutagenicity and hepatocarcinogenicity of MeIQx were examined in mice harboring the lacZ mutation reporter gene ($Muta^{TM}$ Mice) and bitransgenic mice over-expressing the c-myc oncogene. C57B1/$\lambda$lacZ and bitransgenic c-myc (albumin promoter)/$\lambda$lacZ mice were bred and weaned onto an AIN-76 based diet containing $0.06\%$ (w/w) MeIQx or onto control diet. After 30 weeks on diet, only male bitransgenic mice on MeIQx developed hepatocellular carcinoma ($100\%$ incidence) indicating that there was synergism between c-myc over-expression and MeIQx. By 40 weeks, hepatic tumor incidence was $100\%$ ($17\%$) and $44\%$ ($0\%$) in male c-myc/$\lambda$lacZ and C57B1/$\lambda$lacZ mice given MeIQx (or control) diet, respectively, indicating that either MeIQx or c-myc over-expression alone eventually induced hepatic tumors. At either time point, mutant frequency in the lacZ gene was at least 40-fold higher in MeIQx-treated mice than in control mice of either strain. These findings suggest that MeIQx-induced hepatocarcinogenesis is associated with MeIQx-induced mutations. Elevated mutant frequency in MeIQx-treated mice also occurred concomitant with the formation of MeIQx-guanine adducts as detected by the $^{32}P$-postlabeling assay. Irrespective of strain or diet, sequence analysis of the lacZ mutants from male mouse liver showed that the principal sequence alteration was a single guanine-base substitution. Adenine mutations, however, were detected only in animals on control diet. MeIQx-fed mice harboring the c-myc oncogene showed a l.4-2.6-fold higher mutant frequency in the lacZ gene than mice not carrying the transgene. Although there was a trend toward higher adduct levels in c-myc mice, MeIQx-DNA adduct levels were not significantly different between c-myc/$\lambda$lacZ and C57B1/$\lambda$lacZ mice after 30 weeks on diet. Thus, it appeared that factors in addition to MeIQx-DNA adduct levels, such as the enhance rate of proliferation associated with c-myc over-expression, may have accounted for a higher mutant frequency in c-myc mice. In the control diet groups, the lacZ mutant frequency was significantly higher in c-myc/$\lambda$lacZ mice than in 057B1/$\lambda$1acZ mice. The findings are consistent with the notion that c-myc over-expression is associated with an increase in mutagenesis. The mechanism for the synergistic effects of c-myc over-expression on MeIQx hepatocarcinogenicity appears to involve an enhancement of MeIQx-induced mutations.

• BMB Reports
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• v.38 no.1
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• pp.97-103
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• 2005

Under the condition of expression of $\lambda$ P protein at lethal level, the oriC DNA-binding activity is significantly affected in wild-type E. coli but not in the rpl mutant. In purified system, the $\lambda$ P protein inhibits the binding of both oriC DNA and ATP to the wild-type DnaA protein but not to the rpl DnaA protein. We conclude that the $\lambda$ P protein inhibits the binding of oriC DNA and ATP to the wild-type DnaA protein, which causes the inhibition of host DNA synthesis initiation that ultimately leads to bacterial death. A possible beneficial effect of this interaction of $\lambda$ P protein with E. coli DNA initiator protein DnaA for phage DNA replication has been proposed.

• BMB Reports
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• v.29 no.1
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• pp.88-91
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• 1996

The anaerobically expressed gene aeg-46.5, which had been identified by the operon fusion technique with a hybrid bacteriophage of ${\lambda}$ and Mu, ${\lambda}$placMu53, was studied for its expression pattern and growth. The expression of aeg-46.5 was studied in the wild-type cell and mutant cells that have mutation (s) in the control gene of anaerobic respiration (fnr) and nitrate response (narL and narP). The ${\beta}$-galactosidase reporter gene showed maximum expression in narL host after two hours of aerobic to anaerobic switch in M9-Glc-nitrate medium. Both 40 mM and 100 mM concentrations of nitrate ion in the medium had little effect on expression level. We propose that aeg-46.5 is subject to multiple regulations of anaerobic activation by Fnr, nitrate activation by NarP and repression mediated by NarL.

• KIPS Transactions on Computer and Communication Systems
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• v.12 no.5
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• pp.157-164
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• 2023

Specifying the semantic structure for functional interfaces and lambda expressions, which are the latest features of Java, can be referenced when designing similar functions in the future, and is also required in the process of standardizing or implementing an optimized translator. In this study, action equation 3.0 is newly proposed to express the static and dynamic semantic structure of functional interfaces and lambda expressions by modifying and upgrading the existing expressions to express the semantic structures of java functional interfaces and lambda expressions. Measure the execution time of java programs by implementing the semantic structure specified in action equation 3.0 in java, and prove that action equation 3.0 is a real semantic structure that can be implemented through simulation. The superiority of this action equation 3.0 is to be confirmed by comparing the action equation 3.0 specified in the four areas of readability, modularity, extensibility and flexibility with the existing representative semantic expression methods.

• KSBB Journal
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• v.20 no.2 s.91
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• pp.112-115
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• 2005

E. coli in combination with bacteriophage $\lambda$ was used to overcome the intrinsic plasmid instability that is frequently found in recombinant fermentation especially in long-term operation. In order to enhance the stability and productivity, the bacteriophage ${\lambda}NM1070$ was used in this study. It is a $\lambda$ mutant, which is deficient in the synthesis of protein related to DNA packaging and cell lysis. The ${\lambda}NM1070$ is also a temperature-sensitive mutant. To optimize the production of recombinant protein in this temperature-sensitive system, the temperature effects on growth and cloned gene expression were investigated for stable and efficient recombinant gene expression. The induction to the lytic state was not complete at $36^{\circ}C$ while the temperature above $40^{\circ}C$ induced the lytic state completely. However, the productivity was decreased at $42^{\circ}C$ by temperature inhibition. The L-free cell concentration increased with the increase of temperature until $40^{\circ}C$. In conclusion, ${\lambda}NM1070$ has the optimal temperature at $38^{\circ}C$ for stability and at $40^{\circ}C$ for expression.

• Korean Journal of Plant Tissue Culture
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• v.24 no.2
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• pp.93-97
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• 1997

For the molecular genetic study of cold tolerance mechanism in plants, a cDNA encoding fatty acid desaturase (fad3), converting linoleic acid (18:2, $\omega$-6) to linolenic acid (18:3, $\omega$-3), was isolated from $\lambda$ZAPII Arabidopsis thaliana cDNA expression library by plaque hybridization using fad3 cDNA probe derived from Brassica napus. A 1.8 kb-EcoRI fragment from a lambda clone showing a strong positive hybridization signal was subcloned into pGEM7 and analyzed for its nucleotide sequence. From deduced amino acid sequences, the fad3 gene was revealed to have an open reading frame(ORF) consisting of 386 amino acids with a molecular mass of 44,075 Da. The fad3 gene was compared to chloroplast $\omega$-3 fatty acid desaturase (fad7) and endoplasmic reticulum Δ12 fatty acid desaturase (fad2) to show 70% and 58% amino acid sequence homology, respectively, Especially, amino acids of internal (82 to 151) and carboxy terminal (276 to 333) regions were highly conserved, implying their requisite role for enzymatic functioning of fatty acid desaturases. IPTG-induced fad3 cDNA expression in E. coli cells was suggested to be toxic to bacterial growth.

• IMMUNE NETWORK
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• v.3 no.3
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• pp.227-234
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• 2003

Background: Immunoglobulin (Ig) light chain repertoire has been implicated as a critical determinant in regulation of autoreactive B cells and production of pathogenic anti-DNA antibodies in systemic lupus erythematosus (SLE). We analyzed the impact of Ig ${\lambda}$ chain repertoire on development of autoimmunity in patients with SLE. Methods: We obtained genomic DNA from individual peripheral CD19+ B cells of 3 untreated active SLE patients, and amplified $V{\lambda}$ rearrangements from each single cell by polymerase chain reaction. Results: A total number of 208 $V{\lambda}J{\lambda}$ rearrangements were analyzed. Analyzed sequences included 158 productive rearrangements and 50 nonproductive rearrangements. The differences in $V{\lambda}$ gene usage in the productive and nonproductive repertoire of SLE patients were found compared to the non-autoimmune individuals. $V{\lambda}$ gene, 9A was significantly overrepresented in nonproducative repertoire of SLE patients (P=0.016). In the productive repertoire, $V{\lambda}$ genes, 3L and 1E were found more often in the SLE patients (P=0.001, P=0.043). When the productive and the nonproductive repertoires were compared, 9A was found significantly less in the productive repertoire in the SLE patients (P=0.000). There were no significant differences in the $J{\lambda}$ gene usage between SLE patients and non-autoimmune individuals, but $J{\lambda}2/3$ gene was the most frequently used in SLE, whereas $J{\lambda}7$ gene was the most frequently used in the normal subjects. In the productive SLE $V{\lambda}$ repertoire, 9.4% of the total sequences employed identical CDR3. It was particularly striking to find 7 identical versions of the 1G-$J{\lambda}2/3$ $V{\lambda}J{\lambda}$ rearrangements from one patient and 3 of the same sequence from another patient. Notably, identical $V{\lambda}$ junctions in the SLE patients utilized significantly more homologous joining compared to $V{\lambda}$ junctions of the normal adults (P=0.044). Conclusion: These data demonstrate regulation of ${\lambda}$ light chain expression in the SLE patients by selection of unique $V{\lambda}$ genes. Also, biased selection and clonal expansion of particular $V{\lambda}$ rearrangements are apparent in the SLE ${\lambda}$ repertoire.

• Microbiology and Biotechnology Letters
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• v.23 no.6
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• pp.784-788
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• 1995

The lambda Integrase (Int) carries out site-specific recombination between the two partner DNA sequences, attachment P (attP) and attachment B (attB). In order to study the recombination mechanism, a large quantity of pure integrase is required. Then, we constructed an int gene inserted recombinant plasmid (pNYL3) by using the pQE31 HIS-Tag vector, and produced the fusion protein, 6xHIS-Int from the E. coli TG1 strain carrying the pNYL3 plasmid. The recombinant protein produced was purified by phosphocellulose and Ni$^{++}$-NTA affinity column chromatographies. The result of the in vitro recombination assay using the standard reaction mixture containing 6xHIS-Int and partially purified integration host factor (IHF) showed that the 6xHIS-Int tagged recombination Integrase had the full recombination activity.

• Journal of Microbiology and Biotechnology
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• v.5 no.1
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• pp.14-17
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• 1995

Endoglucanase gene of Pseudomonas sp. LBC505 was previously cloned in pUC19 to yield plasmid pLCl. The Pseudomonas sp. LBC505 endoglucanase gene was subcloned in a temperature-regulated Es-cherichia coli expression vector, pAS1, containing the leftward promoter $P_L$ of bacteriophage lambda. The level of gene expression was controlled by the thermal inactivation of the heat-sensitive lambda cI857 repressor. Best yield of endoglucanase was obtained by lowering the incubation temperature to $37^{\circ}C$ after induction at $42^{\circ}C$ for 1h. Under these conditions enzyme production continued for about 5h at a gradually decreasing rate. Ecoli harboring recombinant plasmid pASC10 expressed 4.3 times as much CMCase activity as E.coli containing pLCl. To enhance the expression level of endogl, ucanase gene, we have also changed the presumptive Shine-Dalgamo sequence (AGAGGT) of the gene to consensus sequence (AGGAGGT) by site-directed mutagenesis. The genes mutated were subcloned in pASl resulting in the formation of recombinant plasmid pASS50. E.coli harboring the plasmid pASS50 expressed 6.2-fold higher levels of CMCase activity than that of E.coli harboring pLC1.