• Korean Journal of Microbiology
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• v.46 no.2
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• pp.113-121
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• 2010

Bacillus subtilis PhoP-PhoR two-component system (TCS) senses phosphate deficiency conditions, and then controls expression of the Pho regulon to prolong survival. The sensor histidine kinase, PhoR, is autophosphorylated and transfers the phosphate to the response regulator, PhoP. Phosphorylated PhoP (PhoP~P) binds to repeated 6-bp consensus PhoP binding sequences of Pho regulon promoters and activates or represses gene expression. Pho signal transduction systems are part of interconnected signal transduction network involving at least three TCSs (PhoP-PhoR, ResD-ResE TCS, SpoOA phosphorelay), a global carbon metabolism regulator (CcpA), and transition state regulators (AbrB, ScoC). In addition, PhoP-PhoR TCS is cross related with YycF-YycG TCS by cross-regulation. While indescribable progress has been made in understanding phosphate deficiency stress response through refined expression of the Pho regulon in the recent past years, many important questions still remain. Solving these questions may provide important information for application study using B. subtilis.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.11 no.3
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• pp.459-464
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• 2007

Resolution 122 requires to study power limitation applicable for HAPS ground stations to facilitate sharing with space station receivers in 47/48GHz bands. ITU-R Recommendation 1481-1 recommends to improve the side lobe characteristics of HAPS ground station antenna for frequency sharing between FSS system and HAPS system. In this paper, we propose the maximum allowable off-axis e.i.r.p. level of HAPS ground station antennas by considering power limitation to HAPS ground station in Resolution 122, and by improving the side lobe characteristics of HAPS ground station antennas in Recommendation SF.1481-1. The simulation results show that the unfeasible sharing distance between HAPS ground station and FSS earth station can be reduced remarkably, and give the possibility of frequency sharing between two above systems.

• Korean Journal of Microbiology
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• v.32 no.3
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• pp.186-191
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• 1994

The origin of the leading strand replication (ori) and of lagging strand replication (M-O) of R-plasmid pSBK203 was identified and its base sequence was determined. About 50 bp of ori sequence residues overlapped with the structural gene of rep. Sequence comparison reveals that pSBK-ori shares obvious identities with those of pT181 family and consists of two regions, one is conserved and the other is variable region. Of two palindrome sequence located one after another in upstream region of rep gene, palA' instead of palA which shares sequence homology with diverse family of plasmids such as pOX6, pC194, and pE194 seems to act as a signal for conversion of primarily replicated ssDNA to dsDNA (minus origin (M-O)).

• Toxicological Research
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• v.18 no.4
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• pp.325-330
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• 2002

In this study, the biochemical role of genetic polymorphism in modulating urinary excretion of benzene metabolite as phenol level has been investigated in 90 workers exposed to benzene in the petroleum refinery plant of Korea. The mean concentration of volatile benzene in the refinery environment was 0.042 mg/㎥ (SD, 0.069) and that of urinary phenol was 7.42 mg/g creatinine (SD, 11.3). The frequencies of CYP2E1 genotypes, namely CYP2E1$^*1$/$^*1$, CYP2E1$^*1$/$^*2$ and CYP2E1$^*2$/$^*2$ were 2.2% (2 subjects), 6.7% (G subjects) and 91.1% (85 subjects), respectively, and allele frequencies for CYP2E1$^*1$ and CYP2E1$^*2$ were 0.06 and 0.94. The airborne benzene concentration was significantly related to the concentration of phenol in urine (r = 0.640, p < 0.01). The urinary phenol level was significantly correlated with CYP2E1$^*2$/$^*2$ (r = 0.590, p < 0.05). The various biological (i.e. age and liver function parameters) or lifestyle factors (i.e. medication, smoking, alcohol and coffee intake), also taken into account as potential confounders, did not influence the correlation found. These results suggested that CYP2E1 genotypes might play an important role in the metabolism of benzene.

• Korean Journal of Microbiology
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• v.40 no.2
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• pp.104-110
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• 2004

To determine evolution and genotype of new chromosomal AmpC $\beta$-lactamases among clinical isolates of Enterobacter species, we performed antibiotic susceptibility testing, pI determination, sequencing, and phy-logenetic analysis using developed expression/secretion vector. Six isolates have shown to produce AmpC $\beta$-lactamases. Six genes of AmpC $\beta$-lactamases that are responsible for the resistance to cephamycins (cefoxitin and cefotetan), amoxicillin, cephalothin, and amoxicillin-clavulanic acid were cloned and characterized in pMSG12119. Insert fragment containing the ampC genes was sequenced and found to have an open reading frame coding for 381-amino-acid $\beta$-lactamase. The nucleotide sequence of four ampC genes ($bla_EcloK992004.l$, $bla_EcloK995120.1$, $bla_EcloK99230$, and $bla_EareK9911729$) shared considerable homology with that of chromosomal ampC gene ($bla_EcloMHN1$) of E. cloacae MHN1 (more than 99.6% identity). The sequences of two ampC genes ($bla_EcloK9973$ and $bla_EcloK9914325$) showed close similarity to the chromosomal ampC gene ($bla_EcloQ908R$) of E. clo-acae 908R (99.7% identity). The results from phylogenetic analysis suggested that six ampC genes could be originated from $bla_EcloMHN1$ / or $bla_EcloQ908R$ / MIC patterns and exact pI values of six transformants indicated that the developed expression/secretion vector (pMSG1219) was suitable for the characterization of foreign genes in E. coli strain.

• Korean Journal of Environmental Biology
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• v.26 no.2
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• pp.87-93
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• 2008

To assess effects of contaminants on fish in Nakdong river, feral yellowfin goby Acanthogobius flavimanus were caugt in two different sites and its hepatic monooxygenase enzyme, including cytochrome P450 (CYP), NADPH-cytochrome P450 reductase (P450R), NADH-cytochrome b5 reductase (b5R), ethoxyresorufin deethylase (EROD), glutathione S-transferase (GST) were quantitatively determined. Gonadosomatic index (GSI), hepatosomatic index (HSI) and three sex steroid hormone (17$\beta$-estradiol, E2; testosterone, T; 11-ketotestosterone, 11-KT) levels of the fish were also investigated. HSI of fish from polluted site (site 1) were significantly higher than that of unpolluted site (site 2), but GSI levels were significantly lower in polluted site. No significant differences in plasma 11-KT and T levels were observed in two sites surveyed. E2 level was, however, significantly (p<0.05) higher in female fish from site 1 than site 2. In addition, hepatic EROD activity and CYP level of site 1 fish were lower than those of site 2 fish, whereas relatively high levels of P450R, b5R and GST activities were found in site 1. The results imply that yellowfin goby, especially female fish in Nakdong river estuary are affected from contaminants disrupting sex steroid hormone system.

• Genomics & Informatics
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• v.19 no.3
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• pp.29.1-29.10
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• 2021

In our previous studies, we have demonstrated the association of certain variants of the thyroid-stimulating hormone receptor (TSHR), thyroid peroxidase (TPO), and thyroglobulin (TG) genes with congenital hypothyroidism. Herein, we explored the mechanistic basis for this association using different in silico tools. The mRNA 3'-untranslated region (3'-UTR) plays key roles in gene expression at the post-transcriptional level. In TSHR variants (rs2268477, rs7144481, and rs17630128), the binding affinity of microRNAs (miRs) (hsa-miR-154-5p, hsa-miR-376a-2-5p, hsa-miR-3935, hsa-miR-4280, and hsa-miR-6858-3p) to the 3'-UTR is disrupted, affecting post-transcriptional gene regulation. TPO and TG are the two key proteins necessary for the biosynthesis of thyroid hormones in the presence of iodide and H₂O₂. Reduced stability of these proteins leads to aberrant biosynthesis of thyroid hormones. Compared to the wild-type TPO protein, the p.S398T variant was found to exhibit less stability and significant rearrangements of intra-atomic bonds affecting the stoichiometry and substrate binding (binding energies, ΔG of wild-type vs. mutant: -15 vs. -13.8 kcal/mol; and dissociation constant, K_d of wild-type vs. mutant: 7.2E^-12 vs. 7.0E^-11 M). The missense mutations p.G653D and p.R1999W on the TG protein showed altered ΔG(0.24 kcal/mol and 0.79 kcal/mol, respectively). In conclusion, an in silico analysis of TSHR genetic variants in the 3'-UTR showed that they alter the binding affinities of different miRs. The TPO protein structure and mutant protein complex (p.S398T) are less stable, with potentially deleterious effects. A structural and energy analysis showed that TG mutations (p.G653D and p.R1999W) reduce the stability of the TG protein and affect its structure-functional relationship.

• Proceedings of the KIEE Conference
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• 1996.11a
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• pp.95-98
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• 1996

Response speed of generator/control system kas increased with the aid of the development of power electronics. Even though it is desirable to enhance response speed for the control system(AVR/Gov) of generator itself, in case a certain generator/control system with high response excitation system is connected with bulk power system, terminal voltage and active power of some generators can oscillate with adjoining generators or near area when even a little of disturbance take place. PSS(Power System Stabilizer) is used to damp rotor swing by adding the supplementary signal in phase with speed. As the stable AVR response is very important before PSS is installed, modeling and analysis of generator/control system was performed. Next we have analysed PSS response of Hanlim's gas turbine by transmission line open/close test.

• IMMUNE NETWORK
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• v.11 no.5
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• pp.268-280
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• 2011

Background: Dengue virus, which belongs to the Flavivirus genus of the Flaviviridae family, causes fatal dengue hemorrhagic fever (DHF) and dengue shock syndrome (DSS) with infection risk of 2.5 billion people worldwide. However, approved vaccines are still not available. Here, we explored the immune responses induced by alternating prime-boost vaccination using DNA vaccine, adenovirus, and vaccinia virus expressing E protein of dengue virus type 2 (DenV2). Methods: Following immunization with DNA vaccine (pDE), adenovirus (rAd-E), and/or vaccinia virus (VV-E) expressing E protein, E protein-specific IgG and its isotypes were determined by conventional ELISA. Intracellular CD154 and cytokine staining was used for enumerating CD4+ T cells specific for E protein. E protein-specific CD8+ T cell responses were evaluated by in vivo CTL killing activity and intracellular IFN-${\gamma}$ staining. Results: Among three constructs, VV-E induced the most potent IgG responses, Th1-type cytokine production by stimulated CD4+ T cells, and the CD8+ T cell response. Furthermore, when the three constructs were used for alternating prime-boost vaccination, the results revealed a different pattern of CD4+ and CD8+ T cell responses. i) Priming with VV-E induced higher E-specific IgG level but it was decreased rapidly. ii) Strong CD8+ T cell responses specific for E protein were induced when VV-E was used for the priming step, and such CD8+ T cell responses were significantly boosted with pDE. iii) Priming with rAd-E induced stronger CD4+ T cell responses which subsequently boosted with pDE to a greater extent than VV-E and rAd-E. Conclusion: These results indicate that priming with live viral vector vaccines could induce different patterns of E protein-specific CD4+ and CD8+ T cell responses which were significantly enhanced by booster vaccination with the DNA vaccine. Therefore, our observation will provide valuable information for the establishment of optimal prime-boost vaccination against DenV.

• The Plant Pathology Journal
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• v.16 no.2
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• pp.98-104
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• 2000

For the taxonomic evaluaition, 15 strains of the genus Pectobacterium and Erwinia were analyzed for 16S-23S rDNA intergenic spacer regions (ISRs). These species contained two types of ISRs, large and small ISRs. Large ISRs were on the range of 474-569 bp size, and coding transfer $\textrm{RNA}^{11e}$($\textrm{tRNA}^{11e}$) and $\textrm{tRNA}^{Ala}$. Small ISRs were 354-459 bp in length and coding $\textrm{tRNA}^{Glu}$. The sequence variations of two ISRs among species and strains were very high as compared with 16S rRNA gene sequences. By phylogenetic trees on the basis of two ISRs, Pectobacterium ere differentiated into P. carotovorum-P. cactiaidum group and P. chrysanthemi group. However, the taxonomic position of E. cypripedii and E. rhapontici, which were not clear on taxonomic delineation between Pectobacterium and Erwinia, were not clearly resolved on the basis of ISRs.