• Molecules and Cells
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• 제25권1호
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• pp.131-137
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• 2008

Crk-associated substrate (CAS) is a focal adhesion protein that is involved in integrin signaling and cell migration. CAS deficiency reduces the migration and spreading of cells, both of which are processes mediated by Rac activation. We examined the functions of v-Crk, the oncogene product of the CT10 virus p47gag-crk, which affects cell migration and spreading, membrane ruffling, and Rac activation in CAS-deficient mouse embryonic fibroblasts (CAS-/- MEFs). CAS-/- MEFs showed less spreading than did CAS+/+ MEFs, but spreading was recovered in mutant cells that expressed v-Crk (CAS-/-v-Crk MEF). We observed that the reduction in spreading was linked to the formation of membrane ruffles, which were accompanied by Rac activation. In CAS-/- MEFs, Rac activity was significantly reduced, and Rac was not localized to the membrane. In contrast, Rac was active and localized to the membrane in CAS-/-v-Crk MEFs. Lamellipodia protrusion and ruffle retraction velocities were both reduced in CAS-/- MEFs, but not in CAS-/-v-Crk MEFs. We also found that microinjection of anti-gag antibodies inhibited the migration of CAS-/-v-Crk MEFs. These findings indicate that v-Crk controls cell migration and membrane dynamics by activating Rac in CAS-deficient MEFs.

• 한국미생물·생명공학회지
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• 제19권4호
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• pp.419-427
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• 1991

에탄올의 발효 생산성을 높이기 위해서는 발효조의 균체농도를 높여 고농도의 배양을 해야하며 또한 에탄올에 의한 저해 작용을 감소시켜 비생산성을 향상시키기 위해서는 발효액 중에 축적되는 에탄올을 배출 시킬 필요가 있다. 이와 같은 목적으로 본 연구에서는 고분자 hollow fiber membrane, ceramic filter를 이용하여 가장 중요한 조작 변수인 희석율과 bleed stream ratio가 에탄올 생산성에 미치는 영향 및 조작의 문제점과 장기 조업 가능성을 검토하였다.

• Journal of Microbiology and Biotechnology
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• 제19권12호
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• pp.1635-1643
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• 2009

The aim of this study was to provide new insight into the mechanism whereby the housekeeping enzyme glyceraldehyde-3-phosphate dehydrogenase (GAPDH) locates to cell walls of Lactobacillus plantarum 299v. After purification, cytosolic and cell wall GAPDH (cw-GAPDH) forms were characterized and shown to be identical homotetrameric active enzymes. GAPDH concentration on cell walls was growth-time dependent. Free GAPDH was not observed on the culture supernatant at any time during growth, and provoked cell lysis was not concomitant with any reassociation of GAPDH onto the cell surface. Hence, with the possibility of cw-GAPDH resulting from autolysis being unlikely, entrapment of intracellular GAPDH on the cell wall after a passive efflux through altered plasma membrane was investigated. Flow cytometry was used to assess L. plantarum 299v membrane permeabilization after labeling with propidium iodide (PI). By combining PI uptake and cw-GAPDH activity measurements, we demonstrate here that the increase in cw-GAPDH concentration from the early exponential phase to the late stationary phase is closely related to an increase in plasma membrane permeability during growth. Moreover, we observed that increases in both plasma membrane permeability and cw-GAPDH activity were delayed when glucose was added during L. plantarum 299v growth. Using a double labeling of L. plantarum 299v cells with anti-GAPDH antibodies and propidium iodide, we established unambiguously that cells with impaired membrane manifest five times more cw-GAPDH than unaltered cells. Our results show that plasma membrane permeability appears to be closely related to the efflux of GAPDH on the bacterial cell surface, offering new insight into the understanding of the cell wall location of this enzyme.

• The Korean Journal of Physiology and Pharmacology
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• 제13권1호
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• pp.15-22
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• 2009

This study was undertaken to elucidate the underlying mechanisms of ATP depletion-induced membrane transport dysfunction and cell death in renal proximal tubular cells. ATP depletion was induced by incubating cells with 2.5 mM potassium cyanide(KCN)/0.1 mM iodoacetic acid(IAA), and membrane transport function and cell viability were evaluated by measuring $Na^+$-dependent phosphate uptake and trypan blue exclusion, respectively. ATP depletion resulted in a decrease in $Na^+$-dependent phosphate uptake and cell viability in a time-dependent manner. ATP depletion inhibited $Na^+$-dependent phosphate uptake in cells, when treated with 2 mM ouabain, a $Na^+$ pump-specific inhibitor, suggesting that ATP depletion impairs membrane transport functional integrity. Alterations in $Na^+$-dependent phosphate uptake and cell viability induced by ATP depletion were prevented by the hydrogen peroxide scavenger such as catalase and the hydroxyl radical scavengers(dimethylthiourea and thiourea), and amino acids(glycine and alanine). ATP depletion caused arachidonic acid release and increased mRNA levels of cytosolic phospholipase $A_2(cPLA_2)$. The ATP depletion-dependent arachidonic acid release was inhibited by $cPLA_2$ specific inhibitor $AACOCF_3$. ATP depletion-induced alterations in $Na^+$-dependent phosphate uptake and cell viability were prevented by $AACOCF_3$. Inhibition of $Na^+$-dependent phosphate uptake by ATP depletion was prevented by antipain and leupetin, serine/cysteine protease inhibitors, whereas ATP depletion-induced cell death was not altered by these agents. These results indicate that ATP depletion-induced alterations in membrane transport function and cell viability are due to reactive oxygen species generation and $cPLA_2$ activation in renal proximal tubular cells. In addition, the present data suggest that serine/cysteine proteases play an important role in membrane transport dysfunction, but not cell death, induced by ATP depletion.

• Journal of Microbiology
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• 제41권2호
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• pp.137-143
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• 2003

The present study was performed to identify pathogenic factors of Chlamydia trachomatis, which invade the host cell membrane. We prepared monoclonal antibody against C. trachomatis and searched for pathogenic factors using this antibody, and subsequently identified the surface components of the elementary body of C. trachomatis, i.e., major outer membrane protein (MOMP), lipopolysaccharide (LPS), and two other surface exposure proteins. These proteins are believed to be important in the pathogenesis of host cell chlamydial infection. Additionally, to identify factors related to the host cell and C. trachomatis, we prepared C. trachomatis infected and non-infected McCoy cell extracts, and reacted these with anti-chlamydial LPS monoclonal antibody. We found that anti-chlamydial LPS monoclonal antibody reacted with a 116 kDa proteinaceous McCoy cell membrane component.

• Biotechnology and Bioprocess Engineering:BBE
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• 제9권3호
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• pp.147-150
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• 2004

Permeabilization is known to overcome cell membrane barriers of whole cell biocatalysts. The use of organic solvents is advantageous in terms of cost, simplicity, and efficiency. In this study, Ochrobactrum anthropi SY509 was permeabilized with various organic solvents. Treatment with organic solvents resulted in lower permeability barriers due to falling out lipids of the cell membrane. Therefore, permeabilized cells showed higher enzyme activity with no cell viability. Among various organic solvents, 0.5% (v/v) chloroform was selected as the most efficient permeabilizing reagent. Changes in the cell membrane structure were observe d and the residual amounts of phospholipids of the cell membrane were measured to investigate the mechanism of the improved permeability.

• 대한약리학회:학술대회논문집
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• 대한약리학회 2006년도 The 6th Congress of the Federation of Asian and Oceanian Physiological Societies
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• pp.110.2-110.2
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• 2006

• Advances in Energy Research
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• 제2권1호
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• pp.21-31
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• 2014

The use of a microporous membrane along with Au/C catalyst for direct glycerol alkaline fuel cell was investigated. In comparison with Nafion 112, the microporous Celgard 3401 membrane provides a better cell performance due to the lower ionic resistance as confirmed by impedance spectra. The single cell using Au/C as anode catalyst prepared by using PVA protection techniques provided a higher maximum power density than the single cell with commercial PtRu/C at $18.65mW\;cm^{-2}$ The short-term current decay studies show a better stability of Au/C single cell. The higher activity of Au/C over PtRu/C was owing to the lower activation loss of Awe. The magnitude of current decay indicates a low problem of glycerol crossover from anode to cathode side. The similar performance of single cell with and without humudification at cathode points out an adequate transport of water through the microporous membrane.

• 한국산학기술학회논문지
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• 제20권6호
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• pp.95-103
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• 2019

대표적인 치주질환인 치주염은 출혈, 통증 및 치아 손실을 초래하며, 산화적 스트레스는 치주염의 주요 원인으로 알려져 있다. 본 연구는 지방조직 유래 무막줄기세포추출물의 $H_2O_2$ 유도 산화적 손상에 대한 치주염 보호 효과를 확인하고자, 치주인대 섬유모세포(human periodontal ligament fibroblasts; HPLF)를 이용하여 세포 생존율, 염증 및 세포 사멸 관련 단백질 발현을 측정하였다. $H_2O_2$로 산화적 스트레스를 유도한 HPLF 세포에 무막줄기세포추출물 처리 시, $H_2O_2$만을 처리한 control군에 비해 유의적으로 세포 생존율이 증가함을 통해 산화적 손상에 대한 세포 보호 효과를 확인하였다. 또한, 무막줄기세포추출물은 nuclear factor kappa light chain enhancer of activated B cells, inducible nitric oxide synthase 및 interleukin-6와 같은 염증 관련 단백질 발현을 감소시켜 $H_2O_2$로 유도된 염증반응 보호 효과를 확인할 수 있었다. 뿐만 아니라, 무막줄기세포추출물 처리 군은 caspase-9, -3, poly (ADP-ribose) polymerase 단백질 발현 감소와 B-cell lymphoma 2 (Bcl-2)-associated X protein/Bcl-2 비율을 저하시켜 $H_2O_2$ 유도 산화적 손상에 대한 세포사멸 보호 효과를 보였다. 따라서 지방조직 유래 무막줄기세포추출물은 $H_2O_2$ 유도 산화적 손상에 대한 HPLF 세포의 염증반응 및 세포사멸을 저해함으로써 치주염으로부터 보호 효과가 있어, 치주질환 치료용 소재로써의 활용 가능성이 있을 것으로 기대된다.

• 한국가스학회지
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• 제8권3호
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• pp.16-23
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• 2004

현재 많은 연구가 진행되고 있는 막반응기를 이용한 수소 생산기술은 열역학적 평형의 한계(thermodynamic equilibrium limit)를 뛰어 넘는 생산성을 얻을 수 있음과 동시에 생산되는 수소를 별다른 과정이나 장치 없이 분리할 수 있다는 점에서 경제적으로 매우 기대되는 공정이다. 메탄의 개질반응에서 생성되는 합성가스에 수증기를 첨가하면 널리 알려진 수성가스전환반응이 이루어진다. 이 반응은 수소 생산 공정에 사용되는 주요 반응 중 하나이다. 본 연구에서는 새롭게 제안된 cell을 이용한 해석 기법을 통해 막반응기를 모사하여 막을 이용하지 않은 반응기의 모사 결과와 비교 분석하였으며, 막반응기의 우수성을 검증해 보았다. 막을 사용하지 않은 반응기에서 압력의 영향에 따른 반응속도의 변화는 수성가스전환반응에서 무시할 수 있을 만큼 작았다. 막반응기에서 튜브 측(tube side)의 압력은 높을수록, 쉘 측(shell side)의 압력은 낮을수록 CO의 전환율이 좋았다. 낮은 온도에서 반응의 속도가 낮았으며, 온도가 증가함에 따라 점차 증가하여 600$\pm$30K에서 최대의 CO전환율을 가졌으며 더 증가하면 열역학적 평형의 감소로 인하여 점차 감소하였다. Cell을 이용한 막반응기 모델은 미분방정식을 이용한 모델보다 간단하게 모사를 할 수 있었으며, 신뢰할만한 모사 결과를 얻을 수 있었다.