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Mun, Hueong-Tae,Namgung, Jeong,Namgung, Jeong-Hee-Namgung The Ecological Society of Korea 2000 Journal of Ecology and Environment Vol.23 No.2
Mass loss and changes of mineral nutrients during decomposition of Phragmites communis for 13 months from November 1998 to December 1999, were investigated at the fringe of stream at Boryeong, Chungnam Province in Korea. Plant materials, which were collected in November 1998. were divided into leaves, culms and rhizomes. Litterbags, 15${\times}$15 cm, were made of nylon mesh with 2-mm$^2$ holes. At 13 months after installation, remaining mass of leaves, culms and rhizomes was 29.0%, 57.4%, 20.6%, respectively. Mass loss rate of the culms was significantly lower than those of the leaves and rhizomes. The decay rate of leaves, culms and rhizomes was 1.21. 0.42 and 1.48 per year, respectively. Initial concentration of N, P, K, Ca and Mg of leaves. culms and rhizomes was 22.5, 9.0, 15.5 mg/g for N, 0.34. 0.10, 0.33 mg/g for P, 15.0, 12.5. 12.3 mg/g for K, 2.84. 0.80, 0.03 mg/g for Ca. 1.94. 0.97, 0.40 mg/g for Mg, respectively. Concentrations of nutrients were higher in leaves than in culms and rhizomes. Except for N and Mg in rhizomes, there was no immobilization period during the decomposition. In the case of remaining K and Ca, most are lost during the first 3 months. Without any suitable method for removal of dead part, eutrophication of freshwater may be accelerated by dead macrophytes.
Ecofriendly one-pot biosynthesis of indigo derivative dyes using CYP102G4 and PrnA halogenase
Namgung, Seyun,Park, Hyun A.,Kim, Joonwon,Lee, Pyung-Gang,Kim, Byung-Gee,Yang, Yung-Hun,Choi, Kwon-Young Elsevier 2019 Dyes and pigments Vol.162 No.-
<P><B>Abstract</B></P> <P>In this study, the biosynthesis of various indigoids with novel spectral features and antibacterial activities was investigated. First, 12 indole derivatives as substrates were biotransformed into functional indigoid dyes by <I>E. coli</I> cells expressing CYP102G4 hydroxylase. The indole derivatives included chloro (Cl-), nitro (NO<SUB>2</SUB>-), hydroxy (HO-), methoxy (CH<SUB>3</SUB>O-), methyl (CH<SUB>3</SUB>-), carboxy (COOH-), amino (NH<SUB>3</SUB>-), and cyano (CN-) indoles at the C4 to C7 positions. Interestingly, dramatic color shifts were observed from blue to red, green, purple, and even pink depending on the functional groups and their positions. Next, the biological and physical properties, antibacterial effects, and dying fastness of the prepared compounds were investigated and visually measured. Among the synthesized indigoid dyes, 6,6’-dichloroindigo and 5,5’-dichloroindigo showed the relatively higher cell growth inhibitory activity in the liquid phase. Finally, a one-pot producing strain which produced 7,7’-dichloroindigo from <SMALL>L</SMALL>-tryptophan using tryptophan-7-halogenase (PrnA) and CYP102G4 simultaneously was developed to overcome the disadvantages of uneconomical semi-synthesis through indole precursor feedstocks. The developed producing strain produced approximately 15.4 ± 1.4 mg/L of 7,7’-dichloroindigo in 24 h. To the best of our knowledge, this is the first report of the production of 7,7’-dichloroindigo in <I>E. coli</I> via a one-pot process.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Biological production of eco-friendly indigo derivatives. </LI> <LI> Biotransformation of indole derivatives using CYP102G4. </LI> <LI> One-pot biosynthesis of 7,7’-dichloroindigo by CYP102G4 and PrnA. </LI> <LI> 15.4 mg/L of 7,7’-dichloroindigo production in <I>E. coli</I>. </LI> <LI> Antibacterial activity of indigo derivatives. </LI> </UL> </P>
Dual bio-responsive gene delivery via reducible poly(amido amine) and survivin-inducible plasmid DNA
Namgung, Ran,Brumbach, Jonathan H.,Jeong, Ji Hoon,Yockman, James W.,Kim, Sung Wan,Lin, Chao,Zhong, Zhiyuan,Feijen, Jan,Engbersen, Johan F. J.,Kim, Won Jong Springer-Verlag 2010 Biotechnology letters Vol.32 No.6
<P>A bioreducible poly(amido amine) (SS-PAA) gene carrier, known as poly (amido-butanol) (pABOL), was used to transfect a variety of cancer and non-cancer cell lines. To obtain cancer-specific transgene expression for therapeutic efficiency in cancer treatment, we constructed survivin-inducible plasmid DNA expressing the soluble VEGF receptor, sFlt-1, downstream of the survivin promoter (pSUR-sFlt-1). Cancer-specific expression of sFlt-1 was observed in the mouse renal carcinoma (RENCA) cell line. pABOL enhanced the efficiency of gene delivery compared to traditional carriers used in the past. Thus, a dual bio-responsive gene delivery system was developed by using bioreducible p(ABOL) for enhanced intracellular gene delivery and survivin-inducible gene expression system (pSUR-sFlt-1 or pSUR-Luc reporter gene) that demonstrates increased gene expression in cancer that has advantages over current gene delivery systems.</P>
Namgung, Ho,Kim, Choongho,Kim, Yujun,Kim, Jongho,Lee, Taek Seung American Scientific Publishers 2016 Journal of Nanoscience and Nanotechnology Vol.16 No.8
<P>We report the synthesis of a fluorescent polymer containing the rhodamine 6G (Rh6G) derivative as a side chain. The rhodamine (Rh) moiety in the polymer had a ligand interaction with Al3+, which allowed the polymer to be used for detection of Al3+. The Rh moiety (in closed form) was non-fluorescent and colorless, whereas the open form of the Rh derivative showed strong fluorescence. Upon exposure to Al3+, the green-emitting polymer backbone had a spectral overlap with the absorption of the open form of Rh in the side chain, leading to an energy transfer from the polymer backbone to the Rh moiety. Upon addition of Al3+ to the polymer solution, the emission of the polymer backbone (green) has gradually decreased and, concomitantly, the red emission of Rh has increased via Forster resonance energy transfer (FRET). As the fluorescence of the polymer varied in the presence of Al3+ ions, the polymer could be used as a FRET-based sensor for detecting Al3+.</P>
Namgung, Bumseok,Ong, Peng Kai,Wong, Yun Hui,Lim, Dohyung,Chun, Keyoung Jin,Kim, Sangho IOP Pub 2010 PHYSIOLOGICAL MEASUREMENT Vol.31 No.9
<P>We have recently proposed a computer-based method utilizing a thresholding algorithm (the Otsu method) to provide a convenient way of measuring the cell-free layer width <I>in vivo</I> and <I>in vitro</I>. However, this method does not seem to be a universal method that can be applied to all microvascular studies. Thus, we examined four different histogram-based thresholding algorithms (Otsu, intermode, minimum and second peak) to provide a technical suggestion on the selection of a suitable thresholding algorithm for the cell-free layer measurement. All the measurements were taken in microvascular flows in the rat cremaster muscle recorded with a high-speed camera. The width of the cell-free layer manually measured was compared with that determined by the automated method utilizing the four thresholding algorithms. With our experimental system, results showed that the cell-free layer width determined by the minimum algorithm was in best accordance with the manual measurement. We concluded that the accuracy of the automated methods for determination of the cell-free layer width would depend on the image quality, in particular on the contrast between the red blood cell core and background, which might differ due to the different microscopic setup. Therefore, one may need to examine several appropriate thresholding methods when selecting the best suitable algorithm for the experimental conditions.</P>