• Biotechnology and Bioprocess Engineering:BBE
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• 제8권5호
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• pp.309-312
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• 2003

The transformation capacity (T$\_$c/) of Methylosinus trichosporium OB3b in the degradation of ethylene chlorides was determined by measuring the decrease of soluble methane monooxygenase (sMMO) activity of resting cells in batch experiments. All measurements of sMMO activity were taken in the presence of 20 mM formate to avoid the deficiency of reducing power, and within 2 hrs to avoid the effect of natural inactivation from instability of the resting cells. The constant T$\_$c/ values of 0.58 ${\pm}$ 0.132 and 0.80 ${\pm}$ 0.17 ${\mu}$mol/mg cell were obtained for trichloroethylene (TCE) and 1,2-dichloroethylene (cis and trans-1,2-DCE), respectively, regardless of their concentrations. The transformation capacity measured by this method can be used to predict the amount of cells that should be stimulated in in-situ bioremediation.

• 약학회지
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• 제36권4호
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• pp.315-320
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• 1992

The amino acid threonine was produced from glycine and ethanol in a reaction mixture using resting cells of a newly isolated gram-negative methylotrophic bacterium, capable of growth on methanol. The isolate could utilize $C_1$ compounds and a variety of multicarbon substrates as sole carbon and energy source. To obtain cells of isolate with high threonine producing activity, we investigated optimum cultural conditions. Optimal growth was at the initial concentration of 0.5%(v/v) methanol, at $30^{\circ}C$ and pH 7.0. The growth was not affected by antibiotics inhibiting cell wall synthesis, but was completely suppressed by those inhibiting protein synthesis. The optimum reaction conditions from threonine production by resting cells of this strain were found.

• Fisheries and Aquatic Sciences
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• 제8권1호
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• pp.17-26
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• 2005

The ultrastructure of germ cells during spermatogenesis and the structural changes in the epithelial cells of the seminal vesicle with testicular development in male Neptunea (Barbitonia) arthritica cumingii were investigated monthly based on electron microscopic and histologic observations. N. arthritica cumingii (Gastropod: Buccinidae) undergoes internal fertilization and possesses a modified type of spermatozoon, which is approximately 20$\mu$m long. The axoneme of the tail flagellum consists of nine peripheral pairs of microtubules and one central pair. Many spermatozoa occur in the acini of the testis in the ripe stage and are transported to the seminal vesicles in the accumulating phase. In males, the monthly gonadosomatic index began to increase in September and reached a maximum in February. Subsequently, it decreased rapidly after April. The testis of this species can be classified into four developmental stages: the active (August to September), ripe (October to July), copulation (April to July), and recovery (July to August) stages. Structural changes in the epithelial cells of the seminal vesicles of this species could be classified into three phases: (1) S-I (resting), (2) S-II (accumulating), and (3) S-III (spent) phases. The morphology and structure of the epithelial cells of the seminal vesicle differed in each phase; the cells were cuboidal, squamous, or columnar in the resting, accumulating, or spent phases, respectively.

• The Korean Journal of Physiology and Pharmacology
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• 제9권3호
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• pp.137-141
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• 2005

This study was undertaken to investigate the effects of [$D-Ala^2$, D-Leu^5$]-enkephalin (DADLE) on the spontaneous activity of medial vestibular nuclear neurons of the rat. Sprague-Dawley rats, aged 14 to 16 days, were anesthetized with ether and decapitated. After enzymatic digestion, the brain stem portion of medial vestibular nuclear neuron was obtained by micropunching. The dissociated neurons were transferred to a recording chamber mounted on an inverted microscope, and spontaneous action potentials were recorded by standard patch-clamp techniques. The spontaneous action potentials were increased by DADLE in 12 cells and decreased in 3 cells. The spike frequency and resting membrane potential of these cells were increased by DADLE. The depth of afterhyperpolarization was not affected by DADLE. The potassium currents were decreased in 20 cells and increased in 5 cells. These results suggest that DADLE increases the neuronal activity of the medial vestibular nuclear neurons by altering resting membrane potential.

• The Korean Journal of Physiology and Pharmacology
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• 제7권3호
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• pp.187-191
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• 2003

$Na^+/H^+$ exchanger (NHE) has a critical role in regulation of intracellular pH (pHi) in the renal proximal tubular cells. It has recently been shown that dopamine inhibits NHE in the renal proximal tubules. Nevertheless, there is a dearth of information on the effects of long-term (chronic) dopamine treatment on NHE activities. This study was performed to elucidate the pHi regulatory mechanisms during the chronic dopamine treatments in renal proximal tubular OK cells. The resting pHi was greatly decreased by chronic dopamine treatments. The initial rate and the amplitude of intracellular acidification by isosmotical $Na^+$ removal from the bath medium in chronically dopamine-treated cells were much smaller than those in control. Although it seemed to be attenuated in $Na^+$-dependent pH regulation system, $Na^+$-dependent pHi recovery by NHE after intracelluar acid loading in the dopamine-treated groups was not significantly different from the control. The result is interpreted to be due to the balance between the stimulation effects of lower pHi on the NHE activity and counterbalance by dopamine. Our data strongly suggested that chronic dopamine treatment increased intrinsic intracellular buffer capacity, since higher buffer capacity was induced by lower resting pHi and this effect could attenuate pHi changes under extracellular $Na^+$-free conditions in chronically dopamine-treated cells. Our study also demonstrated that intracellular acidification induced by chronic dopamine treatments was not mediated by changes in NHE activity.

• Journal of Chest Surgery
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• 제21권2호
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• pp.291-298
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• 1988

The effect of Vanadate on the isometric contraction, membrane potential and intracellular calcium ion activities of rabbit myocardial cells were investigated, using calcium selective microelectrode, filled with neutral calcium ion carrier, ETH-1001. The resting tension, the membrane potential and the intracellular calcium ion activities were recorded in normal Tyrode solution and compared with those in the contracture induced by 10 mM Vanadate. The following results were obtained: 1. The dose-response relationship between the contraction of Vanadate and twitch tension showed near-maximum response in 5mM with no corresponding changes in action potential. 2. The resting tension increased up to the amplitude of a control twitch in 10mM Vanadate with resting membrane potential, hyperpolarized. 3. Increase in intracellular calcium ion activities proceeded the contracture by 10mM Vanadate which were restored to the control level in accordance with a decrease of intracellular calcium ion activities. 4. The amplitude of contractures by 10mM Vanadate were 90-120% of the control twitch tension in which the intracellular calcium ion activities were increased about 70 times from p Ca, 7.1 in the control to p Ca, 5.8 in contractures.

• The Korean Journal of Physiology and Pharmacology
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• 제3권6호
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• pp.547-554
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• 1999

The aim of the present study is to investigate the contribution of $Ca^{2+} ?activated\;K^+\;(K_{Ca})$ channels and delayed rectifier $K^+\;(K_V)$ channels to the resting membrane potential (RMP) in rabbit middle cerebral arterial smooth muscle cells. The RMP and membrane currents were recorded using the whole-cell patch configuration and single $K_{Ca}$ channel was recorded using the outside-out patch configuration. Using the pipette solution containing 0.05 mM EGTA, the RMP was $-25.76{\pm}5.08$ mV (n=12) and showed spontaneous transient hyperpolarizations (STHPs). The membrane currents showed time- and voltage-dependent outward currents with spontaneous transient outward currents (STOCs). When we recorded the membrane potential using the pipette solution containing 10 mM EGTA, the RMP was depolarized and did not show STHPs. The membrane currents showed no STOCs but only showed slowly inactivating outward currents. External TEA (1 mM) reversibly inhibited the STHPs, depolarized the RMP, reduced the membrane currents, abolished STOCs, and decreased the open probability of single $K_{Ca}$ channel. When $K_V$ currents were isolated, the application of 4-AP (5 mM) depolarized the RMP. The important aspect of our results is that $K_{Ca}$ channel is responsible for the generation of the STHPs in the membrane potential and plays an important role in the regulation of the RMP and $K_V$ channel is also responsible for the regulation of the RMP in rabbit middle cerebral arterial smooth muscle cells.

• KSBB Journal
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• 제8권4호
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• pp.341-350
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• 1993

본 연구에서는 sMMO를 갖는 메탄 자화균인 M. triclwsporium OB3b를 이용하여 메탄올 생산을 위한 기초실험을 수행하였다. 중요한 결과를 요약하면 다음과 같다(Table 2). 1. 세포 내 NADH의 재생을 위해 개미산을 첨가 할 때 whole-cell의 sMMO 활성은 pH 7.0 및 $30^{\circ}C$ 에서 최대값을 보이며 propylene을 기질로 할 경우 약 130nmol/mg cell min 정도이다. 2. 인산은 MMO와 MDH 활성을 모두 저해하나 M MDH에 대한 저해 정도가 훨씬 크므로 메탄올 합성 에 사용이 가능하다. Noncompetitive mode를 가정 할 때 저해상수는 각각 185mM(MMO) 및 42mM ( (MDH)이었다. 3. 메탄올은 MMO 활성을 저해하며 noncompeti­t tive mode를 가정할 때 propylene기질의 경우 2 21mM 이었다. 4. 균체 내 sMMO 활성은 성장이 멈춰진 상태에 셔 비교적 때}른 속도로 감소하며 고농도 인산용액에 서 그 속도가 더 빨라진다. 5. 인산농도 91mM에서 메탄은 메탄올로 산화되 어 축적되며 4.5시간 동안 에탄올의 생성속도는 평 균 79nmol/mg min이었다.

• Applied Biological Chemistry
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• 제38권1호
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• pp.1-6
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• 1995

Rhodocyclus gelatinosus KUP-74의 고농도 휴지균체로부터 ${\delta}-aminolevulinate$(ALA)를 연속적으로 생산하기 위한 최적조건을 검토하였다. 균체외 ALA양은 20 mg cells/ml의 균체농도까지는 농도 증가에 따른 rectangular hyperbola의 증가양식을 보였으나, 그 이상의 균체농도는 ALA 생산에 전혀 증가효과를 보이지 않았다. 20 mg cells/ml의 반응계에서, 균체외 ALA의 효과적 생산을 위한 첨가물질의 최저농도는 levulinate 4 mM과 L-glutamate 5 mM로 나타났으며, 배양 3시간후 ALA 양의 최대치를 보였다. 한편, Ca-alginate를 이용한 포괄법으로 고정화시킨 균체로부터 효과적으로 ALA를 생산하기 위한 첨가물질의 최적농도는 levulinate 6 mM과 L-glutamate 10 mM로 나타났으며, 배양 6시간째에 균체외 ALA 양의 최대치를 보였다. 또한, 이 조건 하에서 고정화균체와 고농도의 휴지균체에 의한 ALA의 연속생산성을 검토한 결과, 이들 균체에 의한 50% ALA 생산성은 각각 185시간과 100시간에서 나타났으며, 생산된 균체외 ALA의 회수를 위해서는 균체를 고정화시키는 방법이 효과적이었다.

• 한국생물공학회:학술대회논문집
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• 한국생물공학회 2000년도 추계학술발표대회 및 bio-venture fair
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• pp.549-552
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• 2000

본 연구의 석탄에서 분리한 미생물은 유기황인 dibenzotiophene을 2-hydroxybiphenyl로 탈황하며 yeast extract의 첨가로 그 속도가 증가할 수 있음을 관찰할 수 있었다. Resting cell을 이용한 탈황의 경우 화학 계면활성제의 첨가에 의해 그 속도와 정도가 증가함을 관찰할 수 있었다.