• Journal of Microbiology and Biotechnology
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• 제18권3호
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• pp.490-496
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• 2008

Symbiobacterium toebii is a commensal symbiotic thermophile that cannot grow without support from a partner bacterium. We investigated the properties of Symbiobacterium growth-supporting factors (SGSFs) produced by the partner bacterium Geobacillus toebii. SGSFs occurred in both the cell-free extract (CFE) and culture supernatant of G. toebii and might comprise multifarious materials because of their different biological properties. The heavy SGSF contained in the cytosolic component exhibited heat- and proteinase-sensitive proteinaceous properties and had a molecular mass of >50 kDa. In contrast, the light SGSF contained in the extracellular component exhibited heat-stable, proteinase-resistant, nonprotein properties and had a molecular mass of <10 kDa. Under morphological examination using light microscopy, S. toebii cultured with the culture supernatant of G. toebii was filamentous, whereas S. toebii cultured with the CFE of G. toebii was rod-shaped. These results strongly suggest that the SGSFs produced by G. toebii comprise two or more types that differ in their growth-supporting mechanisms, although all support the growth of S. toebii. Upon the examination of the distribution of SGSFs in other bacteria, both cytosolic and extracellular components of Geobacillus kaustophilus, Escherichia coli, and Bacillus subtilis had detectable growth-supporting effects for S. toebii, indicating that common SGSF materials are widely present in various bacterial strains.

• 대한바이러스학회지
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• 제26권2호
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• pp.181-189
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• 1996

Fecal samples of calf diarrhea were taken on farms in Jeju island, rotavirus was isolated and cytopathic effect (CPE) was determined after infection to MA104 cell. Morphological evaluation on electron microscopy proved it as rotavirus. Also, its infection to MA104 cell was reidentified using a fluorescence antibody method. Genotype of Jeju island bovine rotavirus (JBR) analyzed through PAGE was 4: 2: 3: 2 pattern, which was unique in bovine and that analyzed through general PAGE was somewhat different from NCDV, UK, KK3, A5-3A, 61A, B223 and similar to N stool-5, N culture-5 and Kawatabi (Japan). By titration after plaquing, the level was $1-3\;{\times}\;10^6\;PFU/ml$, which was lower than those of NCDV and UK. Electrophoresis analysis of RNA-RNA hybridization, ELISA, and first and second PCR products of VP7 and VP4 in 1% agarose ($TAE+1{\mu}l$ EtBr) revealed that the rotavirus was a serotype of G6P11.

• The Korean Journal of Physiology
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• 제30권2호
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• pp.197-208
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• 1996

Endosomes lower their internal pH by an ATP-driven proton pump, which is critical to dissociation of many receptor-ligand complexes, the first step in the intracellular sorting of internalized receptors and ligands. Endosomes are known to exhibit n great range of pH values that can vary between 5.0 and 7.0 within a single cell although the factors that regulate endosomal pH remain uncertain. To evaluate the morphological and topological differences of endosomes in the different stages, confocal microscopy was used. The early endosomes labeled with fluorescein isothiocyanate-dextran for 10 min at $37^{\circ}C$ were identifiable at the peripheral and tubule-vesicular endosome compartment. In contrast, the late endosomes formed by 10 min pulse and 20 min trace were located deeper in the cytoplasm and showed more vesicular features than early endosomes. For the purpose of determining whether ATP-dependent acidification was heterogeneous and whether the differences in acidification were attributed to differences in the activity of $Na^{+}-K^{+}$-ATPase and/or $Cl^{-}$ channel, endocytic compartments were fractionated into subpopulation using percoll gradient and measured ATP-dependent acidification. While all fractions exhibited ATP-dependent acidification activity, both the initial rate of acidification and extent of proton translocation were lower in early endosomes and gradually increased in late endosomes. Phosphorylation by PKA and ATP enhanced ATP-dependent acidification in both early and late endosomes, hut there was no difference in the degree of enhancement by phosphorylation between two subpopulations. When ATP-dependent acidification was determined in the presence or absence of vanadate ($Na_{3}VO_{4}$) or ouabain, only early endosomes exhibited the vanadate or ouabain dependent stimulation of acidification activity, suggesting the inhibition of $Na^{+}-K^{+}$-ATPase. Therefore, it seems probable that the inhibition of early endosome acidification by $Na^{+}-K^{+}$-ATPase observed in vitro at least in part plays a physiological role in controlling the acidification of early endosomes in vivo.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2012년도 제43회 하계 정기 학술대회 초록집
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• pp.440-440
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• 2012

Nanomaterials have emerged as new building blocks to construct light energy harvesting assemblies. Size dependent properties provide the basis for developing new and effective systems with semiconductor nanoparticles, quantized charging effects in metal nanoparticle or their combinations in 2 and 3 dimensions for expanding the possibility of developing new strategies for photovoltaic system. As top-down approach, we developed a simple and effective method for the large scale formation of self-assembled Cu(In,Ga)$Se_2$ (CIGS) nanostructures by ion beam irradiation. The compositional changes and morphological evolution were observed as a function of the irradiation time. As the ion irradiation time increased, the nano-dots were transformed into a nano-ridge structure due to the difference in the sputtering yields and diffusion rates of each element and the competition between sputtering and diffusion processes during irradiation. As bottom-up approach, we developed the growth of CIGS nanowires using thermal-chemical vapor deposition (CVD) method. Vapor-phase synthesis is probably the most extensively explored approach to the formation of 1D nanostructures such as whiskers, nanorods, and nanowires. However, unlike binary or ternary chalcogenides, the synthesis of quaternary CIGS nanostructures is challenging because of the difficulty in controlling the stoichiometry and phase structure. We introduced a method for synthesis of the single crystalline CIGS nanowires in the form of chalcopyrite using thermal-CVD without catalyst. It was confirmed that the CIGS nanowires are epitaxially grown on a sapphire substrate, having a length ranged from 3 to 100 micrometers and a diameter from 30 to 500 nm.

• Asian Pacific Journal of Cancer Prevention
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• 제13권9호
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• pp.4807-4814
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• 2012

Purpose: The chemoresistance of human hepatocellular carcinoma (HCC) to cytotoxic drugs, especially intrinsic or acquired multidrug resistance (MDR), still remains a major challenge in the management of HCC. In the present study, possible mechanisms involved in MDR of HCC were identified using a 5-fluorouracil (5-FU)-resistant human HCC cell line. Methods: BEL-7402/5-FU cells were established through continuous culturing parental BEL-7402 cells, imitating the pattern of chemotherapy clinically. Growth curves and chemosensitivity to cytotoxic drugs were determined by MTT assay. Doubling times, colony formation and adherence rates were calculated after cell counting. Morphological alteration, karyotype morphology, and untrastructure were assessed under optical and electron microscopes. The distribution in the cell cycle and drug efflux pump activity were measured by flow cytometry. Furthermore, expression of potential genes involved in MDR of BEL-7402/5-FU cells were detected by immunocytochemistry. Results: Compared to its parental cells, BEL-7402/5-FU cells had a prolonged doubling time, a lower mitotic index, colony efficiency and adhesive ability, and a decreased drug efflux pump activity. The resistant cells tended to grow in clusters and apparent changes of ultrastructures occurred. BEL-7402/5-FU cells presented with an increased proportion in S and G2/M phases with a concomitant decrease in G0/G1 phase. The MDR phenotype of BEL-7402/5-FU might be partly attributed to increased drug efflux pump activity via multidrug resistance protein 1 (MRP1), overexpression of thymidylate synthase (TS), resistance to apoptosis by augmentation of the Bcl-xl/Bax ratio, and intracellular adhesion medicated by E-cadherin (E-cad). P-glycoprotein (P-gp) might play a limited role in the MDR of BEL-7402/5-FU. Conclusion: Increased activity or expression of MRP1, Bcl-xl, TS, and E-cad appear to be involved in the MDR mechanism of BEL-7402/5-FU.

• Current Photovoltaic Research
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• 제4권1호
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• pp.16-20
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• 2016

$Cu_2ZnSnS_4$ (CZTS) thin films were fabricated by successive electrodeposition of layers of precursor elements followed by sulfurization of an electrodeposited Cu-Zn-Sn precursor. In order to improve quality of the CZTS films, we tried to optimize the deposition condition of absorber layers. In particular, I have conducted optimization experiments by changing the Cu-layer deposition time. The CZTS absorber layers were synthesized by different Cu-layer conditions ranging from 10 to 16 minutes. The sulfurization of Cu/Sn/Zn stacked metallic precursor thin films has been conducted in a graphite box using rapid thermal annealing (RTA). The structural, morphological, compositional, and optical properties of CZTS thin films were investigated using X-ray diffraction (XRD), Field emission scanning electron microscopy (FE-SEM), Raman spectroscopy, and X-ray Flourescenece Spectrometry (XRF). Especially, the CZTS TFSCs exhibits the best power conversion efficiency of 4.62% with $V_{oc}$ of 570 mV, $J_{sc}$ of $18.15mA/cm^2$ and FF of 45%. As the time of deposition of the Cu-layer to increasing, the properties were confirmed to be systematically changed. And we have been discussed in detail below.

• Carbon letters
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• 제22권
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• pp.48-59
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• 2017

This study synthesized pure anatase carbon doped $TiO_2$ photocatalysts supported on a stainless steel mesh using a sol-gel solution of 8% polyacrylonitrile (PAN)/dimethylformamide (DMF)/$TiCl_4$. The influence of the pyrolysis temperature and holding time on the morphological characteristics, particle sizes and surface area of the prepared catalyst was investigated. The prepared catalysts were characterized by several analytical methods: high resolution scanning electron microscopy (HRSEM), energy dispersive spectroscopy (EDS), X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET), and X-ray photoelectron spectroscopy (XPS). The XRD patterns showed that the supported $TiO_2$ nanocrystals are typically anatase, polycrystalline and body-centered tetragonal in structure. The EDS and XPS results complemented one another and confirmed the presence of carbon species in or on the $TiO_2$ layer, and the XPS data suggested the substitution of titanium in $TiO_2$ by carbon. Instead of using calcination, PAN pyrolysis was used to control the carbon content, and the mesoporosity was tailored by the applied temperature. The supported $TiO_2$ nanocrystals prepared by pyrolysis at 300, 350, and $400^{\circ}C$ for 3 h on a stainless steel mesh were actual supported carbon doped $TiO_2$ nanocrystals. Thus, $PAN/DMF/TiCl_4$ offers a facile, robust sol-gel related route for preparing supported carbon doped $TiO_2$ nanocomposites.

• Journal of Microbiology and Biotechnology
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• 제4권2호
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• pp.113-118
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• 1994

A bacterial strain NS-83 isolated from soil was able to produce an extracellular thermostable protease. The strain was identified as Pseudomonas aeruginosa based on its morphological and physiological characteristics. A thermostable protease from this strain has been purified to homogeneity as judged by SDS-PAGE and isoelectric focusing. The purification procedures included hydrophobic interaction, ion exchange, and gel filtration chromatography. The $M_r$ and the pl of the enzyme were 32,000 and 5.9, respectively. The optimal pH at 55$^{\circ}C$ and the optimal temperature at pH 7.0 were 8.0 and 60$^{\circ}C$, respectively. The D-values of the enzyme at 60, 65, and 70$^{\circ}C$ were 22, 2.1, and 0.75 hrs, respectively. The enzyme activity was significantly inhibited in the presence of 1 mM o-phenanthroline or EDTA, suggesting that the enzyme is metalloprotease. The $K_m$, and $V_{max}$ for Hammarsten casein were found to be 3.2 mg/ml and 0.918 unit/ml, respectively. These enzymatic properties were similar to those of elastase produced from P. aeruginosa IFO 3455, but the enzyme was clearly different from the reported elastase, in respect to $Ca^{++}$ effects on enzyme-thermostability. This property, together with amino acid composition analysis, confirmed that the enzyme differs from the known P. aeruginosa elastase.

• 한국식품영양과학회지
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• 제31권5호
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• pp.754-759
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• 2002

공업적으로 광범위하게 이용되고 있는 protease 중 중성 영역에서 최적의 활성을 갖는 중성 protease에 대한 연구의 일환으로, 토양으로부터 protease의 생성능이 우수한 10여 균주를 순수 분리하였으며, 이들 중에서 protease의 활성 이 가장 우수한 PANH765를 최종 선별하였다. 이 균주의 형태학적, 배양학적, 생리학적 및 생화학적 특성을 조사하여 Bergey의 세균 분류서의 색인에 따라 체계적으로 분류한 결과, Bacilius subtilis 또는 그 유연균으로 동정되어 분리균을 Bacilius .Subtilis PA-NH765로 동정하였다. B. subtilis PANH-765 균주에 의한 protease의 최적 배지 조성은 2.0% glucose, 1.0% yeast extract, 0.2% ammonium nitrate, 0.02% ferrous sulfate 및 0.02% di-potassium hydrogen phosphate이었으며, 최적 생산 조건은 배양온도 ,3$0^{\circ}C$, pH 7.0, 진탕 속도 150 rpm이었다. 이 조건에서 초기 균체량을5%(w/v)접종하여 배양하였을 때 시간에 따른 효소의 최대 활성은 배양 ,36시간일 때 6.34 U이었다.

• 생명과학회지
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• 제10권3호
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• pp.300-306
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• 2000

원유 분해능이 강력한 해양균주를 얻고자 유류오염 지역으로부터 crude oil을 탄소원으로 이용하는 수집 종을 분리하였다. 분리된 균주중 원유분해능 및 성장속도면에서 가장 우수한 균주를 선별하여 KCL-2로 명명하였으며, 형태학적, 생화학적 및 생리학적 특성을 조사한 후 Klebsiella sp.로 동정하였다. KCL-2 균주의 원유 분해를 위한 최적 배양조건은 배양온도 27$^{\circ}C$~37$^{\circ}C$였으며 초기 pH는 7.0이였다. 또 한, 이 균주의 성장은 3.0% 염분농도에서 최대의 성장을 보여주어 해양유래의 균주임을 확인하였다. 비 교적 장쇄인 n-alkane 계 탄화수소의 C18~C28의 탄화수소를 탄소원으로 이용하였다. 원유분해시 C18 의 첨가에 의해 균생육 및 원유 분해능이 촉진되는 것으로 나타났다. KCL-2 균주의 유화활성은 32$^{\circ}C$, pH 7.0의 배양조건에서 배양 3일째에 가장 높게 나타났다.