• BMB Reports
• /
• 제45권2호
• /
• pp.59-70
• /
• 2012

Carbon catabolite repression (CCR) is a key regulatory system found in most microorganisms that ensures preferential utilization of energy-efficient carbon sources. CCR helps microorganisms obtain a proper balance between their metabolic capacity and the maximum sugar uptake capability. It also constrains the deregulated utilization of a preferred cognate substrate, enabling microorganisms to survive and dominate in natural environments. On the other side of the same coin lies the tenacious bottleneck in microbial production of bioproducts that employs a combination of carbon sources in varied proportion, such as lignocellulose-derived sugar mixtures. Preferential sugar uptake combined with the transcriptional and/or enzymatic exclusion of less preferred sugars turns out one of the major barriers in increasing the yield and productivity of fermentation process. Accumulation of the unused substrate also complicates the downstream processes used to extract the desired product. To overcome this difficulty and to develop tailor-made strains for specific metabolic engineering goals, quantitative and systemic understanding of the molecular interaction map behind CCR is a prerequisite. Here we comparatively review the universal and strain-specific features of CCR circuitry and discuss the recent efforts in developing synthetic cell factories devoid of CCR particularly for lignocellulose-based biorefinery.

• 해양환경안전학회지
• /
• 제13권4호
• /
• pp.21-26
• /
• 2007

인공위성영상을 이용한 해양정보 추출을 위하여 SAR 위성영상을 이용한 해수유동 정보 추출을 연구하였다. SAR(Synthetic Aperture Radar) 위성영상의 도플러 쉬프트 정보를 이용한 해수유동 정보 추출은 적용기술의 근본적 한계로 인하여 실제 유속이 아니라 위성궤도의 법선방향에 대한 유속장도만을 제시하는 문제가 있다. 이러한 한계 및 문제점을 극복하기 위하여 본 연구에서는 위성영상 촬영과 동일한 시간에 동일한 해역에서 해수유동을 관측하고, 관측된 해수유동 정보를 이용하여 위성영상에서 추출된 해수유동 정보를 보완 검증하였다. 위성영상 추출 해수유동정보의 위성궤도 법선방향 유속강도는 관측된 해수유동 유향분포도에 근거하여 실제 해수유동 유향에 맞게 보정될 수 있었으며, 보정된 해수유동 정보는 실제 해수유동 분포를 잘 반영할 수 있었다.

• Advances in Traditional Medicine
• /
• 제7권1호
• /
• pp.51-64
• /
• 2007

Mucus is an aqueous gel complex with a constitution of about 95% water, high molecular weight glycoprotein (mucin), lipid, salts etc. Mucus appears to represent a significant barrier to the absorption of some compounds. Natural mucoadhesive agent was isolated and purified from the aqueous extract of the seeds of prosopis pallida (PP). Formulated tablet with the isolated material by wet granulation method. Some natural edible substances are in consideration for candidates as mucoadhesive agents to claim more effective controlled drug delivery as an alternative to the currently used synthetic mucoadhesive polymers. Subjected the materials obtained from natural source i.e. PP and standard synthetic substance, sodium carboxymethyl cellulose for evaluation of mucoadhesive property by various in vitro and in vivo methods. Through standard dissolution test and a model developed with rabbit, evaluated in vitro controlled release and bioadhesive property of theophylline formulation. Mucoadhesive agent obtained from PP showed good mucoadhesive potential in the demonstrated in vitro and in viνo models. The results suggest that the mucoadhesive agent showed controlled release properties by their application, substantially. In order to assess the gastrointestinal transit time in vivo, a radio opaque X-ray study performed in healthy rabbit testing the same controlled release formulation with and without bioadhesive polymer. Plasma levels of theophylline determined by the HPLC method and those allowed correlations to the in vitro mucoadhesive study results. Better correlation found between the results in different models. PP may acts as a better natural mucoadhesive agent in the extended drug delivery system.

• 한국수산과학회지
• /
• 제38권5호
• /
• pp.286-290
• /
• 2005

Oxytocin (OT)-related peptide, isotocin was purified from the brain extract of conger eel (Conger myriaster) using reverse-phase, ion-exchange and size exclusion high performance liquid chromatography (HPLC). The sequence of the peptide, with a molecular weight of 967.30 Da, was determined as Cys-Tyr-Ile-Ser-Asn­Cys-Pro-Ile-Gly-$NH_2$, where the Cys between 1st and 6th residues made an intramolecular disulfide bridge by the automated amino acid sequence analysis and MALDI-TOF mass spectrometry. The sequence was confirmed by identical elution with the purified and synthetic peptide using the HPLC system. As a result of homology investigation, the primary structure of this peptide was the same as that of OT -superfamily member, isotocin. The synthetic peptide showed a contractile activity at a minimal effective concentration of $10^{-7}M$ on the intestinal smooth muscle of goldfish (Carassius auratus).

• Biotechnology and Bioprocess Engineering:BBE
• /
• 제11권5호
• /
• pp.425-431
• /
• 2006

The development of fermentation conditions for the production of C595 diabody fragment (dbFv) in E. coli HB2151 clone has been explored. Investigations were carried out to study the effect of carbon supplements over the expression period, the comparison of C595 dbfv production in synthetic and complex media, the influence of acetic acid upon antibody production, and comparison of one-stage and two-stage processes operated at batch or fed-batch modes in bioreactor. Yeast extract supplied during expression yielded more antibody fragment than any other carbon supply. The synthetic medium presented higher specific productivity (0.066 mg dbFv $g^{-1}$ dry cell weight) when compared to the complex medium (0.044 mg dbFv $g^{-1}$ DCW). The comparison of fermentation strategies demonstrated that (1) one-stage fed-batch fermentation performed higher C595 dbFv production than that operated in batch mode which was significantly affected by acetate concentration; (2) a two-stage batch operation could enhance C595 dbFv production. It was found that a concentration of 12.3 mg $L^{-1}$ broth of C595 dbFv and a cell concentration of 10.8g $L^{-1}$ broth were achieved at the end of two-stage operation in 5-L fermentation.

• Journal of Microbiology and Biotechnology
• /
• 제14권1호
• /
• pp.90-96
• /
• 2004

A synthetic defined medium, fortified with amino acids, was developed for the stable production of the kringle fragments of human apolipoprotein(a) (apo(a)), rhLK68. Using a complex rich medium containing yeast extract and a high-cell-density fed-batch culture, the expression level of rhLK68 reached 17% of the total cellular protein, which corresponded to $5\;g\;l^{-1}$ of the culture. To replace the complex media with chemically defined media, several amino acids that positively affect cell growth and gene expression were chosen by a statistical method. The various combinations of the selected amino acids were tested for its fortifying effect on a minimal defined medium. When glutamine only was added, the overall expression level of rhLK68 reached 93% of the complex rich medium increasing the specific expression level by 22.4% and decreasing the cell growth by 24%. Moreover, the addition of glutamine resulted in a 2-fold increase in the concentration of rhLK68 in the culture broth, compared with the minimal defined medium. The synthetic defined media developed in this study could be generally applied to high-cell-density cultures of the recombinant Escherichia coli BL21(DE3), especially for the production of therapeutic proteins that require a strict quality control of the culture media and fermentation processes.

• 생약학회지
• /
• 제40권2호
• /
• pp.137-142
• /
• 2009

Isoniazid was discovered in 1950's and since then it has been widely used as a synthetic bactericidal agent in the treatment of tuberculosis. However, the adverse effect of isoniazid has been reported to show significant hepatotoxicity in approximately 1-2% of patients. Nitrofurantoin {1-(5-nitro-2-furfurylideneamino)-hydantoin} is a synthetic nitrofuran that is commonly used for the treatment and prophylaxis of urinary tract infections, but its use is associated with liver cirrhosis and fatal liver necrosis. Therefore, studies for natural products with protective effect on the isoniazid- and/or nitrofurantoin-induced hepatotoxcity would be valuable as the potential therapeutic use. 107 plants sources were collected at Mt. Baekdu, and extracted with methanol. These extracts had been screened for the protective effects against isoniazid- and/or nitrofurantoin-induced cytotoxicity in HepG2 cells at the both 100 and $300{\mu}g/ml$. Five methanolic extracts, Acanthopanax senticosus, Acer mono, Asparagus schoberioides, Fagopyrum tataricum, Potentilla centigrana, showed significant protective effects against isoniazidinduced hepatotoxicity. Two methanolic extracts, Acer mono and Leonurus artemisia, showed significant protective effects against nitrofurantoin-induced cytotoxicity in HepG2 cells.

• 전자공학회논문지S
• /
• 제36S권1호
• /
• pp.104-114
• /
• 1999

본 논문에서능 2차원 칼라 동영상으로부터 3차원 개인 얼굴 모델을 자동 생성하는 효율적인 방법을 다루었다. 복잡한 배경이 포함된 영상에서 얼굴 영역을 안정적으로 추출하기 위하여 피부 색상 분포에 근거한 색상 움직임 추출 방법을 이용하였다. 검출된 얼굴 영역 내에서 색상 정보과 경계선 정보를 활용하여, MPEG-4의 SNHC(Synthetic-Natural Hybrid Coding) 에서 제안하고 있는 개개인의 얼굴 특성을 표현하는 31개의 얼굴 특징점 파라메타(Facial Description Rarameter: FDP)를 자동 추출하였다. 추출된 2차원 얼굴 특징점을 1038개의 삼각형 메쉬로 이루어진 3차원 일반 얼굴 모델(Generic model)에 적용시켜 변형함으로써 개개인의 얼굴에 해당하는 모델을 자동 생성하였다. 제안하는 알고리듬은 컬러 동영상에서 배경의 복잡성, 얼굴 크기 등에 상관없이 정면상에 가까운 경우 안정적인 특징점을 추출하였으며, 펜티엄 PC에서 약 2초 이내에 개개인의 얼굴 모습에 유사한 얼굴 모델을 생성할 수 있었다.

• 한국수산과학회지
• /
• 제38권1호
• /
• pp.6-11
• /
• 2005

Vasopressin (VP)-related peptide was purified from the brain extract of conger eel (Conger myriaster) by reverse-phase, ion-exchange high performance liquid chromatography (HPLC). This peptide with a molecular weight of 1,051.2 Da was determined as $H-Cys-Tyr-Ile-Gln-Asn-Cys-Pro-Arg-Gly-NH_2$, whose Cys residues made an intramolecular disulfide bridge by the automated amino acid sequence analysis, MALDI- TOF mass spectrometry. It's sequence was confirmed by identity of the elution position with the synthetic peptide in HPLC system. As a result of homology investigation, the primary structure of this peptide was the same as that of VP-superfamily member, $[Arg^8]-vasotocin$. The synthetic peptide showed a contractile activity at a minimal effective concentration of $10^{-10}\;M$ on the intestinal smooth muscle of goldfish.

• 한국자원식물학회지
• /
• 제21권1호
• /
• pp.28-35
• /
• 2008

산딸나무의 꽃, 잎, 열매, 가지 등 부위별 추출물과 용매 분획물을 제조하여 각각의 생리활성물질 함량, 항산화활성 그리고 tyrosinase 억제활성을 분석하였다. 총 폴리페놀 및 플라보노이드 함량은 다른 부위보다 꽃 추출물에서 169.638 $mg{\cdot}g^{-1}$과 25.418 $mg{\cdot}g^{-1}$으로 가장 높게 나타났다. DPPH 및 ABTS 라디칼 소거활성과 $Fe^{2+}$ chelating 효과 역시 꽃 추출물에서 가장 우수한 것으로 조사되었다. Ferric thiocyante 방법으로 지질 과산화 억제효과를 조사한 결과, 꽃, 잎, 가지의 경우는 BHT보다 높은 억제활성을 보였다. Tyrosinase 억제활성은 오직 꽃 추출물에서만 나타났다. 높은 생리활성을 보인 꽃과 잎 추출물을 n-hexane, chloroform, ethyl acetate, n-butanol의 순으로 용매분획한 결과, 폴리페놀함량은 꽃과 잎 모두 water 분획물에서 각각 67.006 $mg{\cdot}g^{-1}$ 및 66.739 $mg{\cdot}g^{-1}$으로 가장 많았다. 반면 플라보노이드 함량은 꽃의 경우 ethyl acetate 분획물에서 가장 높았고, 잎은 butanol 분획물에서 가장 높게 조사되었다. 자유라디칼 소거활성은 꽃 추출물의 경우 ethyl acetate 분획물에서 가장 높았고 잎 추출물은 butanol 분획물에서 가장 높게 조사되었다. 꽃과 잎의 각 용매 분획물이 tyrosinase의 활성에 미치는 영향을 조사한 결과, 모두 water 분획물에서 각각 49.24% 및 31.8%로 가장 높은 억제 효과를 보였다.