• Journal of Microbiology and Biotechnology
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• v.25 no.4
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• pp.511-520
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• 2015

Triclosan, the widely used biocide, specifically targets enoyl-acyl carrier protein reductase (ENR) in the bacterial fatty acid synthesis system. Although the fish pathogen Aeromonas salmonicida subsp. salmonicida exhibits triclosan resistance, the nature of this resistance has not been elucidated. Here, we aimed to characterize the triclosan resistance of A. salmonicida subsp. salmonicida causing furunculosis. The fosmid library of triclosan-resistant A. salmonicida subsp. salmonicida was constructed to select a fosmid clone showing triclosan resistance. With the fosmid clone showing triclosan resistance, a subsequent secondary library search resulted in the selection of subclone pTSR-1. DNA sequence analysis of pTSR-1 revealed the presence of a chromosomal-borne fabV-encoding ENR homolog. The ENR of A. salmonicida (FabVas) exhibited significant homology with previously known FabV, including the catalytic domain YX₍₈₎K. fabVas introduction into E. coli dramatically increased its resistance to triclosan. Heterologous expression of FabVas might functionally replace the triclosan-sensitive FabI in vivo to confer E. coli with triclosan resistance. A genome-wide search for fabVas homologs revealed the presence of an additional fabV gene (fabVas2) paralog in A. salmonicida strains and the fabVas orthologs from other gram-negative fish pathogens. Both of the potential FabV ENRs expressed similarly with or without triclosan supplement. This is the first report about the presence of two potential FabV ENRs in a single pathogenic bacterium. Our result suggests that triclosan-resistant ENRs are widely distributed in various bacteria in nature, and the wide use of this biocide can spread these triclosan-tolerant ENRs among fish pathogens and other pathogenic bacteria.

• Analytical Science and Technology
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• v.6 no.4
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• pp.349-357
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• 1993

Analytical methods of thromboxane $B_2(TXB_2)$ using various techniques of Fast Atom Bombardment mass spectrometry (FAB MS) were studied, static FAB condition was investigated to obtain linear response curve using docosanoic acid as a internal standard. For maximum sensitivity, a continuos-flow(CF-) FAB MS by selected-ion monitoring(SIM) with devised sample introduction system, has been developed to quantiate thromboxane $B_2$ in biological sample. Instrumental parameters affecting sensitivity, reproducibility has been studied. The method has been optimized with respect to the eluent, 0.75% glycerol(in EtOH v/v) and flow rate of $3.7{\mu}l/min.$ Under the condition, detection limits were below 10pg in SIM mode and a good linear relationship between dose and response was achieved.

• BMB Reports
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• v.30 no.4
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• pp.253-257
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• 1997

Negative ion fast atom bombardment (FAB) mass spectra were found to allow the determination of the linkage positions in a series of underivatized linkage-isomeric oligosaccharides. A previous work (Laine et al., 1988) reported that ion patterns of linkage-isomeric trisaccharides could be distinguished by a positive ion. Negative ion FAB collison-activated dissociation (CAD) mass spectrometry (MS) spectra of trisaccharides exhibited better sensitivity than the positive ion mode and provided specific fragmentation patterns according to the linkage positions. Especially, the fragmentations, m/z 205 in F6 and m/z 221 in G6, not occuring in 1-3 or 1-4 linkage. were an indication of 1-6 linkage, by changing collision energies from + 10 eV to +60 eV. The survival ratios of molecular ions in each collision energy set gave support to previous results in which the order of bond stability was 1-6>1-4>1-3 linkage.

• Applied Science and Convergence Technology
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• v.26 no.5
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• pp.139-142
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• 2017

In this paper, InP-based InGaAs/InAlAs quantum cascade lasers(QCLs) providing nearly zero emission wavelength mismatch between the measured emission wavelength and the designed transition wavelength of QCLs is presented. The zero emission wavelength mismatch of QCLs influenced by both the accurate compositions and thicknesses of the low-pressure metal-organic vapor-phase epitaxy(MOVPE) grown InGaAs and InAlAs layers throughout the core and the abrupt composition transitions between InGaAs and InAlAs layers. The abrupt interfaces between InGaAs and InAlAs layers have been achieved throughout the core structure by means of controlling individually purged vent/run valves of a closed coupled showerhead reactor. In addition, maintaining substrate temperature constant during InGaAs/InAlAs core growth was a partial factor of uniformity improvement of QCLs. These approaches for reducing the possible discrepancies between the designed and MOVPE grown epitaxial structures could lead to improvement of QCL performance.

• Current Photovoltaic Research
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• v.4 no.3
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• pp.108-113
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• 2016

III-V compound semiconductor based thin film solar cells promise relatively higher power conversion efficiencies and better device reliability. In general, the thin film III-V solar cells are fabricated by an epitaxial lift-off process, which requires an $Al_xGa_{1-x}As$ ($x{\geq}0.8$) sacrificial layer and an inverted solar cell structure. However, the device performance of the inversely grown solar cell could be degraded due to the different internal diffusion conditions. In this study, InGaP/GaAs double-junction solar cells are inversely grown by MOCVD on GaAs (100) substrates. The thickness of the GaAs base layer is reduced to minimize the thermal budget during the growth. A wide band gap p-AlGaAs/n-InGaP tunnel junction structure is employed to connect the two subcells with minimal electrical loss. The solar cell structures are transferred on to thin metal films formed by Au electroplating. An AlAs layer with a thickness of 20 nm is used as a sacrificial layer, which is removed by a HF:Acetone (1:1) solution during the epitaxial lift-off process. As a result, the flexible InGaP/GaAs solar cell was fabricated successfully with an efficiency of 27.79% under AM1.5G illumination. The efficiency was kept at almost the same value after bending tests of 1,000 cycles with a radius of curvature of 10 mm.

• Proceedings of the PSK Conference
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• 2002.10a
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• pp.315.3-316
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• 2002

A universal set of genes encodes the components of dissociated. type II. fa11y acid synthase system that is responsible for producing the multitude of fa11y acid structures found in bacterial membranes. We examined the biochemical basis for the production of fatty acids by bacteria. Several genes from HaemophHus influenzae Rd and three genes from Enterococcus faecalis V583 were predicted to encode homologs of the ${\beta}$-ketoacyl-acyl carrier protein synthases I or II or III of Escherichia coli(FabB or BabF, or FabH)were identified in the genomic database. The protein products were expressed. purified, and biochemically characterized. efFabH and hF abH carried out the initial condensation reaction of fatty acid biosynthesis with acetyl-Coenzyme A as a primer. and hFabB and efFabF1 carried out the elongation condensation reaction of fatty acid biosynthesis with myrixtoyl-ACP.

• Journal of Sensor Science and Technology
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• v.29 no.5
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• pp.354-359
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• 2020

The high vacuum hermetic sealing technique ensures excellent performance of MEMS resonators. For the high vacuum hermetic sealing, the customization of anodic bonding equipment was conducted for the glass/Si/glass triple-stack anodic bonding process. Figure 1 presents the schematic of the MEMS resonator with triple-stack high-vacuum anodic bonding. The anodic bonding process for vacuum sealing was performed with the chamber pressure lower than 5 × 10^-6 mbar, the piston pressure of 5 kN, and the applied voltage was 1 kV. The process temperature during anodic bonding was 400 ℃. To maintain the vacuum condition of the glass cavity, a getter material, such as a titanium thin film, was deposited. The getter materials was active at the 400 ℃ during the anodic bonding process. To read out the electrical signals from the Si resonator, a vertical feed-through was applied by using through glass via (TGV) which is formed by sandblasting technique of cap glass wafer. The aluminum electrodes was conformally deposited on the via-hole structure of cap glass. The TGV process provides reliable electrical interconnection between Si resonator and aluminum electrodes on the cap glass without leakage or electrical disconnection through the TGV. The fabricated MEMS resonator with proposed vacuum packaging using three-layer anodic bonding process has resonance frequency and quality factor of about 16 kHz and more than 40,000, respectively.

• Applied Biological Chemistry
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• v.50 no.1
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• pp.72-76
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• 2007

In order to examine the biofunctions of glycosylceramide which is representative of sphingolipid, monoglycosylceramide (cerebroside) was isolated from rice bran extract. Crude glycosylceramides were isolated in large quantities and promptly by flash system column chromatography from rice bran extract, and purified by normal-phase HPLC using an evaporative light-scattering detector. One major cerebroside was obtained by HPLC used as an eluent consisting of chloroform, methanol and water (99:11:1, v/v/v), and the constituents were analyzed by MALDI/TOF-MS, FAB-MS, GC and 600 MHz $^1$H-NMR. The component sugar was estimated to be glucose. In the ceramide, the fatty acid component consist was 2-hydroxy arachidic acid. The long-chain base component was sphinga-4,8-dienine.

• Journal of Microbiology and Biotechnology
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• v.24 no.3
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• pp.408-420
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• 2014

Yeast surface-displayed antibody libraries provide an efficient and quantitative screening resource for given antigens, but suffer from typically modest library sizes owing to low yeast transformation efficiency. Yeast mating is an attractive method for overcoming the limit of yeast transformation to construct a large, combinatorial antibody library, but the optimal conditions have not been reported. Here, we report a large synthetic human Fab (antigen binding fragment) yeast surface-displayed library generated by stepwise optimization of yeast mating conditions. We first constructed HC (heavy chain) and LC (light chain) libraries, where all of the six CDRs (complementarity-determining regions) of the variable domains were diversified mimicking the human germline antibody repertoires by degenerate codons, onto single frameworks of VH3-23 and $V{\kappa}1$-16 germline sequences, in two haploid cells of opposite mating types. Yeast mating conditions were optimized in the order of cell density, media pH, and cell growth phase, yielding a mating efficiency of ~58% between the two haploid cells carrying HC and LC libraries. We constructed two combinatorial Fab libraries with CDR-H3 of 9 or 11 residues in length with colony diversities of more than $10^9$ by one round of yeast mating between the two haploid HC and LC libraries, with modest diversity sizes of ${\sim}10^7$. The synthetic human Fab yeast-displayed libraries exhibited relative amino acid compositions in each position of the six CDRs that were very similar to those of the designed repertoires, suggesting that they are a promising source for human Fab antibody screening.

• Journal of Korea Foresty Energy
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• v.20 no.1
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• pp.42-52
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• 2001

The barks of Fraxinus rhynchophylla, Fraxinus sieboldiana and Fraxinus mandshurica, ash trees grown in domestic, were collected, extracted with acetone-H$_2$O(7:3, v/v) and freeze dried to give some dark brown powder. A portion of the freeze dried powder was chromatographed on a Sephadex LH-20 and a TSK 40F column using a series of aqueous methanol, ethanol and ethanol-hexane mixture as eluents Some spectrometric analyses such as NMR and FAB-MS including TLC were performed to identify the structures of the isolated compounds. The bark extractives contained a large amount of coumarin derivatives in addition to a small amount of ester compounds.