• 한국생물공학회:학술대회논문집
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• 2001.11a
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• pp.189-192
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• 2001

We have investigated the effects of abiotic and biotic stresses on leaf senescence using transgenic tobacco plants, in which cellular contents of polyamines were increased by introducing the genes of polyamine and ethylene biosynthesis in sense or antisense orientation. These transgenic plants showed accumulations of polyamines at higher levels than were found in wild-type. Stress-induced senescence was attenuated in transgenic plants cpmpared with wild-type plants, in terms of total chlorphyll loss and phenotypic changes after oxidative stress of hydrogen peroxide($H_2O_2$), high salinity, acid stress (pH3.0), ABA and fungal pathogen(phytophothora parasitica pv.Nicotianae). Transcripts for antioxidant enzyme, glutathionine-S-transferase and catalase, were also more abundant in transgenic plants than wild-type plants. These result suggested that higher expression of those genes caused a broad-spectrum resistance to abiotic stress/biotic stress. These phenomena indicate that polyamines may play an important role in contributing to the antioxidant defense function in plants. Our findings suggest that facilitate the improvement of stress tolerance of crop plants.

• Journal of Microbiology
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• v.40 no.4
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• pp.305-312
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• 2002

The effects of two natural polyamines (putrescine and spermidine) on the synthesis of ArcA, a response regulator of the Arc two-component signal transduction system, were studied using an E. coli mutant deficient in polyamine biosynthesis. Endogenous polyamine deficiency of the mutant resulted in marked reduction in the ArcA level determined by Western blot analysis. Putrescine supplement to the growth medium effectively increased the ArcA level of the mutant in a concentration-dependent manner. Spermidine also stimulated the ArcA level in the mutant to a greater degree than putrescine. Expression of arcA'::lacZ operon fusion in the mutant was stimulated 6-fold and 10-fold by putrescine and spermidine at a 1mM concentration, respectively, indicating that the stimulatory effect of the polyamines on ArcA synthesis is due to transcriptional induction, and that spermidine is a more potent arcA inducer than putrescine. The polyamine-dependent arcA'::lacZ induction was growth-phase-dependent and independent of either arcA or fnr which are two regulators involved in anaerobic stimulation of the Arch level. These results suggested that putrescine and spermidine polyamines may be potential intracellular signal molecules in the control of arcA expression, and thereby may play an important role in cellular metabolism.

• Proceedings of the Plant Resources Society of Korea Conference
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• 2011.10a
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• pp.14-14
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• 2011

Polyamines (putrescine, spermidine and spermine) play pivotal roles in plant defense to different abiotic and biotic stresses. In order to understand the function of ginseng spermidine synthase gene, a key gene involved in biosynthesis of polyamines, transgenic plant was generated in Arabidopsis. The transgenic plants exhibited high levels of polyamines compared to the untransformed control plants. We investigated the tolerance capacity of transgenic plants to abiotic stresses such as salinity and copper stress. In addition, transgenic plants also showed increased resistance against one of the important fungal pathogens of ginseng, the wilt causing Fusarium oxysporum and one of important bacteria, bacterial blight causing Pseudomonas syringae. However, an activity of the polyamine catabolic enzyme, diamine oxidase (DAO) was increased significantly in F. oxysporum and P. syringae infected transgenic plant. Polyamine catabolic enzymes which may trigger the hypersensitive response (HR) by producing hydrogen peroxide ($H_2O_2$) seem act as an inducer of PR proteins, peroxidase and phenyl ammonium lyase activity. The transgenic plants also contained higher antioxidant enzyme activities, less MDA and $H_2O_2$ under salt and copper stress than the wild type, implying it suffered from less injury. These results strongly suggest an important role of spermidine as a signaling regulator in stress signaling pathways, leading to build-up of stress tolerance mechanisms.

• Journal of the Korean Chemical Society
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• v.48 no.2
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• pp.123-128
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• 2004

Quantum chemical quantities, enthalpy of formation(${\Delta}H_f$), HOMO and LUMO energy, and dipole moment(${\mu}_D$) were acquired by AM1, PM3, and ZINDO/1 methods for polyamines and imidazole derivatives. The investigation of the inhibitory activity on some Ni(II) complexes with polyamines and imidazole derivatives is performed by ZINDO/1 calculations. It was found that experimental inhibitory activity(IA) appeared when the value of net charge and enthalpy of formation were over 0.03 and -300 eV, respectively for Ni(II) complexes. These results showed that the Ni(II) complexes have exception on the following very unstable compounds: square pyramidal [Ni(dpt)(tn)])]$^{2+}$(dpt=3,3'-diaminodipropylamine)(tn=1,3-diaminopropane) and distorted tetrahedral [Ni(N-PropIm))$_2$(NCS))$_2$](N-PropIm=N-Propylimidazole).

• The Korean Journal of Physiology and Pharmacology
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• v.7 no.3
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• pp.131-142
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• 2003

We have studied mutant forms of Kir2.1 in which an aspartate residue (D172), important for gating by intracellular polyamines, is replaced by one of three basic residues (Arg, Lys or His). Such channels are highly selective for $K^+$, but show inward rectification that is a shallow function of voltage compared with that found in wild type. This inward rectification occurs with a reduced affinity for spermine and persists in the absence of polyamines. Though the unitary current-voltage relation shows some inward rectification, it is insufficient to account for that seen under whole cell recording. Channels open and shut under single channel recording, and changes of $P_{open}$ appear to generate inward rectification. In D172H, the reduction in affinity for spermine is greater when His is protonated at low $pH_i$. The effective valency for spermine is reduced from $3.09{\pm}0.07$ in wild type to $1.95{\pm}0.09$ in D172H at $pH_i$ 6.3. In the presence of dual mutants of Kir2.1, where E224 is also replaced, spermine affinity becomes undetectable. However, channels still show inward rectification and open and shut under hyper- and depolarisation, respectively. We suggest that Kir2.1 channel are able to undergo conformation changes; these changes may be important physiologically in generating inward rectification, the normal parameters of which are set by the binding of polyamines such as spermine.

• Korean Journal of Soil Science and Fertilizer
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• v.33 no.4
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• pp.247-252
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• 2000

Polyamine concentrations were clearly enhanced in leaves and chloroplasts by Cd treatment, but not in thylakoid and PSII. It appeared that newly synthesized polyamines by Cd are distributed in stromal space. The accumulated polyamines in stromal space could not be adjacent to thylakoid membranes, suggesting that they are already saturated. The levels of putrescine and spermine were about 36 and 20 fold lower in chloroplast than in whole leaf cells respectively, whereas agmatine level was only 3.7 fold lower. The inhibitory effect of Cd nn $O_2$ evolving process was obviously alleviated by 0.2mM spermine supplement. Polyamines stimulated $O_2$ evolution within the range of 0.5mM in spinach thylakoids. It was also found that stimulating effect of polyamines is about 2 fold higher in dicothyledonous spinach than in monocotyledonous wheat at same concentrations. Furthermore, the enhanced activity of $O_2$ evolution was lowered rather by agmatine treatment than by putrescine treatment in wheat, suggesting a difference between monocot and dicot.

• Journal of Life Science
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• v.15 no.4 s.71
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• pp.626-632
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• 2005

The polyamines are essential components of all eukaryotic cells and absolutely necessary for cell growth. In the present study, the cytoprotective role of polyamine was characterized. When $Ac_2F$ rat liver cells were treated with 1M 2,2'-azobis (2-amidinopropane) dehydrochloride (AAPH), a water soluble free radical initiator, viability of the cells was noticeably decreased due to the increase of reactive oxygen species (ROS). The cytotoxic effect of AAPH as well as ROS generation were significantly inhibited by the treatment of polyamines. Among polyamines, especially spermine at $20{\mu}M$ concentration exerted over $45\%$ inhibition of AAPH-induced ROS generation. Western blotting was performed to determine whether superoxide dismutase(SOD) or catalase (CAT) expression was involved in oxidative stress. The AAPH treatment blocked both SOD and CAT protein expressions. Spermine could recover those protein expressions to the untreated control levels. According to the result of cycline E measurement, AAPH might block the entry of the cells into S phase of the cell cycle. The reduced expression of cyclin E protein could be fully recovered by the addition of spermine. The antioxidative effects of spermine was also further proved by the apopotitic morphological analysis using ethidium bromide and acridine orange.

• Bulletin of the Korean Chemical Society
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• v.27 no.10
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• pp.1667-1670
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• 2006

• Proceedings of the Zoological Society Korea Conference
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• 2000.10a
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• pp.208.1-208
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• 2000

No Abstract, See Full Text

• Proceedings of the Korean Society of Life Science Conference
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• 2001.09a
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• pp.112-112
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• 2001