• Korean Journal of Environment and Ecology
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• v.30 no.1
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• pp.130-134
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• 2016

How does $CO_2$ affect on the stomatal mechanism? The mechanism of stomatal opening by $CO_2$ is not clear as it is difficult to see $CO_2$ effect on light-induced stomatal opening. Furthermore, stomata may react differently according to the concentration of $CO_2$. The significance of the possible endogenous rhythms must consider to understand on $CO_2$-related response. It is clear that $CO_2$ has an effect on the accumulation of osmotic materials which determines the degree of stomatal apertures because it is known that stomata open in the condition of the reduced $CO_2$ concentration. However, it is not fully understood how $CO_2$ leads to the stomatal opening. It has been thought that $CO_2$ can not affect on the ion fluxes which determines the increase of osmotic potential in guard cells. However, in this study, the changes of guard cell membrane permeability by $CO_2$ have been focused on. There are many reports that $CO_2$ related reactions are dominant when the leaf is exposed to certain a mount of $CO_2$. The hypothesis of the stomatal opening by light is based on the increase of osmotic materials in guard cells including $K^+$, $Cl^-$, sucrose and $malate^{2-}$. It was reported that $CO_2$ induced a big hyperpolarization indicating that $H^+$ was extruded to the cell outside. It was also found that $CO_2$ caused guard cell membrane hyperpolarization in the intact leaf up to 3 or 4 times higher than that of light induced membrane hyperpolarization. These results represent that $CO_2$ can affect on the change of physical characteristics which affects on the change of the membrane permeability.

• Journal of Life Science
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• v.18 no.8
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• pp.1023-1030
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• 2008

NtMEK2, which is the tobacco MAPK kinase that is upstream of SIPK and WIPK, was identified using the dexamethasone (DEX)-inducible gain-of-function transgenic system. Expression of $NtNEK2^{DD}$, a constitutively active mutant of NtNEK2, leads to HR-like cell death, which indicates that the NtMEK2-SIPK/WIPK cascade controls defense responses in tobacco. However, little is known about the downstream target substrates or defense-related genes that are regulated by the NtMEK2-SIPK/ WIPK cascade. In this study, ACP-based differential display RT-PCR was used to isolate the downstream effectors mediated by the NtMEK2-SIPK/WIPK cascade in $NtNEK2^{DD}$ transgenic plants. The results identified 6 novel differentially expressed genes (DEGs). These included pathogen induced protein 2-4 (pI2-4), monoterpene synthase 2 (MTS2), seven in absentia protein (SINA), cell death marker protein 1 (CDM1), hydroxyproline-rich glycoprotein (HRGP) and unknown genes (DEG45). The induction of these genes was confirmed by RT-PCR of samples obtained from $NtNEK2^{DD}$ plants. Additionally, when compared with other isolated DEGs, the pI2-4, CDM1 and HRGP genes were significantly up-regulated in response to treatment with salicylic acid and tobacco mosaic virus. Taken together, these results suggest that three novel DEGs were regulated by the NtMEK2-SIPK/WIPK cascade involved in disease resistance in tobacco.

• Applied Microscopy
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• v.35 no.1
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• pp.31-39
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• 2005

Synapses are contact points where one neuron communicates with another. The morphological change of synapses under various physiological or pathological conditions has long been hypothesized to modify their functional properties. 3-dimensional (3-D) reconstruction of synapses with serial ultrathin sections has contributed to the understanding of ultrastructural dimensions and compositions of synapses. The 3-D reconstruction procedures, however, require a great amount of expertise as well as include prohibitively timeconsuming processes. Here, we introduce efficient 3-D reconstruction technique using high-voltage electron microscopy (HVEM). Primarily, we established an optimal section thickness and staining condition to observe synaptic structures in detail under HVEM. The result showed that synaptic profiles were preserved at the section thickness of 250 nm without the overlapping of synaptic ultrastructures. An increase in the reaction time of en bloc staining was most efficient to enhance contrast than the extension of postembedding staining or the addition of uranyl acetate during dehydration. Then, 3-D reconstruction of parallel fiber-Purkinje cell synapses in the rat cerebellum was carried out with serial HVEM images and reconstruction software. The images were aligned and the contours of synapses were outlined on each section. 3-D synapses were finally extracted from the section files by grouping all the synaptic contours. The reconstructed synapse model clearly demonstrated the configuration of pre and postsynaptic components. These results suggest that 3-D reconstruction of synapses using HVEM is much efficient and suitable for massive quantitative studies on synaptic connectivity than conventional TEM approach using numerous ultrathin sections.

• Tuberculosis and Respiratory Diseases
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• v.59 no.1
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• pp.30-38
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• 2005

Background : Arsenic trioxide ($As_2O_3$) has been used to treat acute promyelocytic leukemia, and it induces apoptosis in a variety of solid tumor cell lines including non-small cell lung cancer cells. However, nonsteroidal antiinflammatory drugs (NSAID) can enhance tumor response to chemotherapeutic drugs or radiation. It was previously demonstrated that a combination treatment with $As_2O_3$ and sulindac induces the apoptosis of NCI-H157 human lung carcinoma cells by activating the caspase cascade. This study aimed to determine if a combination treatment augmented its apoptotic potential through other pathways except for the activation of the caspase cascade. Material and Methods : The NCI-H157 cells were treated with $As_2O_3$, sulindac and antioxidants such as glutathione (GSH) and N-acetylcysteine (NAC). The cell viability was measured by a MTT assay, and the level of intracellular hydrogen peroxide ($H_2O_2$) generation was monitored fluorimetrically using a scopoletin-horse radish peroxidase (HRP) assay. Western blotting and mitochondrial membrane potential transition analysis were performed in order to define the mechanical basis of apoptosis. Results : The viability of the cells was decreased by a combination treatment of $As_2O_3$ and sulindac, and the cells were protected using antioxidants in a dose-dependent manner. The increased $H_2O_2$ generation by the combination treatment was inhibited by antioxidants. The combination treatment induced changes in the mitochondrial transmembrane potential as well as the expression of the Bcl-2 family proteins, and increased cytochrome c release into the cytosol. However, the antioxidants inhibited the effects of the combination treatment. Conclusion : Combination treatment with $As_2O_3$ and sulindac induces apoptosis in NCI-H157 human lung carcinoma cells via ROS generation with a mitochondrial dysfunction.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.19 no.5
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• pp.492-501
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• 2007

Coastal disasters have become one of the most important issues in every coastal country. In Korea, coastal disasters such as storm surge, sea level rise and extreme weather have placed many coastal regions in danger of being exposed or damaged during subsequent storms and gradual shoreline retreat. A storm surge is an onshore gush of water associated with a tow pressure weather system, typically in typhoon season. However, it is very difficult to predict storm surge height and inundation due to the irregularity of the course and intensity of a typhoon. To provide a new scheme of typhoon damage prediction model, the scenario which changes the central pressure, the maximum wind radius, the track and the proceeding speed by corresponding previous typhoon database, was composed. The virtual typhoon scenario database was constructed with individual scenario simulation and evaluation, in which it extracted the result from the scenario database of information of the hereafter typhoon and information due to climate change. This virtual typhoon scenario database will apply damage prediction information about a typhoon. This study performed construction and analysis of the simulation system with the storm surge/coastal inundation model at Masan coastal areas, and applied method for predicting using the scenario of the storm surge.

• Journal of Life Science
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• v.26 no.8
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• pp.875-880
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• 2016

The plasma membrane plays a crucial role in relaying signals from the outside environment to the inside of the cells. In eukaryotic cells, the inner leaflets of the plasma membrane are composed mostly of phospholipids, including phosphatidylethanolamine (PE), phosphatidylserine (PS), and phosphatidylinositides (PIs). In this study, we tried to analyze the morphological changes induced by EGFP-fused membrane binding proteins, which are targeted to the plasma membrane via specific phospholipids binding. As a result, we found that overexpression of EGFP-P4M-SidM, a specific PI4P binding protein, or EGFP alone, did not induce any morphological changes. On the other hand, overexpression of EGFP-PLCδ1(PH), which is a specific PI(4,5)P₂ binding protein, EGFP-AKT1(PH) which binds to PI(3,4,5)P₃, or EGFP-OSH2(PH)×2 which binds to PI4P and PI(4,5)P₂, could induce the filopodia and lamilapodia formation as well as cell shrinkage. Overexpression of Lact-C2-EGFP which is a specific PS-binding probe, EGFP fused Aplysia phosphodiesterase 4 (ApPDE4) long-form (L(N20)-EGFP) which is localized to the plasma membrane via hydrophobic interaction, or EGFP fused Aplysia PDE4 short-form (S(N-UCR1-2)-EGFP) which is localized to the plasma membrane via electrostatic interaction, could induce cell shrinkage, but not filopodia or lamilapodia formation. Taken together, our data support that the different phospholipid bindings in the plasma membrane could induce different characteristic morphological changes. Thus, we can analyze, characterize, and classify the cellular morphological changes induced by the various phospholipid binding proteins.

• Journal of Life Science
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• v.31 no.9
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• pp.818-826
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• 2021

5-Aminolevulinic acid phosphate (5-ALA-p) is a substance obtained by eluting 5-ALA (a natural delta amino acid) with aqueous ammonia, adding phosphoric acid to the eluate, and then adding acetone to confer properties suitable for use in photodynamic therapy applications. However, its pharmacological efficacy, including potential mechanisms of antioxidant and anti-inflammatory reactions, remains unclear. This study aimed to investigate the effects of 5-ALA-p on oxidative and inflammatory stresses in lipopolysaccharide (LPS)-stimulated RAW 264.7 cells. Our data showed that 5-ALA-p significantly inhibited excessive phagocytic activity via LPS and attenuated oxidative stress in LPS-treated RAW 264.7 cells. Furthermore, 5-ALA-p improved mitochondrial biogenesis reduced by LPS, suggesting that 5-ALA-p restores mitochondrial damage caused by LPS. Additionally, 5-ALA-p significantly suppressed the release of nitric oxide (NO) and pro-inflammatory cytokines, such as tumor necrosis factor α (TNF-α), interleukin (IL)-1β, and IL-6, which are associated with the inhibition of inducible NO synthase and respective cytokine expression. Furthermore, 5-ALA-p reduced the nuclear translocation of nuclear factor-kappa B (NF-κB) and inhibited phosphorylation of mitogen-activated protein kinases (MAPKs), indicating that the anti-inflammatory effect of 5-ALA-p is mediated through the suppression of NF-κB and MAPK signaling pathways. Based on these results, 5-ALA-p may serve as a potential candidate to reduce inflammation and oxidative stress.