• Journal of The Korean Society of Grassland and Forage Science
• /
• v.19 no.3
• /
• pp.281-290
• /
• 1999

The bacterial isopentenyl transferase (ipt) gene involved in cytokinin biosynthesis was fused with 35S promoter of cauliflower mosaic virus (CaMV) and introduced into tobacco plants (Nicotiana tabacum L. cv. Samsun) via Agrobacterium-mediated transformation. As expected, ipt gene was constitutively expressed in all tissues of transgenic plants. Several primary transgenic plants were obtained that expressed different level of transcripts for ipt gene. Three of transgenic plants with different expression level of ipt gene were selected and selfed to obtain homozygous line for further analysis. A number of interesting phenotypic changes such as viviparous leaves, delayed senescence, larger axillary shoots, an abundance of tiny shoots at the apex and a release of lateral buds, were observed in transgenic plants. Chlorophyll content was 1.5- t.o 4-fold higher in transgenic plants as compared with non-transformed plants. These results indicate that the cytokinin synthesized in transgenic plants could improve forage crop yield by delay of leaf senescence and increase of leaf number.

• Journal of Life Science
• /
• v.19 no.8
• /
• pp.1047-1054
• /
• 2009

Oral squamous carcinoma (OSC) cells present resistance to chemotherapeutic agents-mediated apoptosis in the late stages of malignancy. Advances in the understanding of bacterial toxins have produced new strategies for the treatment of cancers. It was demonstrated here that Pseudomonas aeruginosa exotoxin A (PEA) significantly decreased the viability of chemoresistant YD-9 cells in the apoptosis mechanism. Apoptotic manifestations were evident through changes in nuclear morphology and generation of DNA fragmentation. PEA treatment induced caspase-3, -6 and -9 cleavage, and activation. These events preceded proteolysis of the caspase substrates poly (ADP-ribose) polymerase (PARP), DNA fragmentation factor 45 (DFF45), and lamin A in YD-9 cells. The reduction of mitochondrial membrane potential, release of cytochrome c and SmacjDlABLO from mitochondria to cytosol, andtranslocation of AlF into nucleus were shown. While p53, p21 and $14-3-3{\gamma}$ were upregulated, cyclin Band cdc2 were downregulated by PEA treatment. Taken together, PEA induces apoptosis in chemoresistant YD-9 cells via activation of caspases, mitochondrial events and regulation of cell cycle genes.

• International Journal of Oral Biology
• /
• v.34 no.1
• /
• pp.7-14
• /
• 2009

Nitric oxide (NO) acts as an intracellular messenger at the physiological level but can be cytotoxic at high concentrations. The cells within periodontal tissues, such as gingival and periodontal fibroblasts, contain nitric oxide syntheses and produce high concentrations of NO when exposed to bacterial lipopolysaccharides and cytokines. However, the cellular mechanisms underlying NO-induced cytotoxicity in periodontal tissues are unclear at present. In our current study, we examined the NO-induced cytotoxic mechanisms in human gingival fibroblasts (HGF). Cell viability and the levels of reactive oxygen species (ROS) were determined using a MTT assay and a fluorescent spectrometer, respectively. The morphological changes in the cells were examined by Diff-Quick staining. Expression of the Bcl-2 family and Fas was determined by RT-PCR or western blotting. The activity of caspase-3, -8 and -9 was assessed using a spectrophotometer. Sodium nitroprusside (SNP), a NO donor, decreased the cell viability of the HGF cells in a dose- and time-dependent manner. SNP enhanced the production of ROS, which was ameliorated by NAC, a free radical scavenger. ODQ, a soluble guanylate cyclase inhibitor, did not block the SNP-induced decrease in cell viability. SNP also caused apoptotic morphological changes, including cell shrinkage, chromatin condensation, and DNA fragmentation. The expression of Bax, a member of the proapoptotic Bcl-2 family, was upregulated in the SNP-treated HGF cells, whereas the expression of Bcl-2, a member of the anti-apoptotic Bcl-2 family, was downregulated. SNP augmented the release of cytochrome c from the mitochondria into the cytosol and enhanced the activity of caspase-8, -9, and -3. SNP also upregulated Fas, a component of the death receptor assembly. These results suggest that NO induces apoptosis in human gingival fibroblast via ROS and the Bcl-2 family through both mitochondrial- and death receptor-mediated pathways. Our data also indicate that the cyclic GMP pathway is not involved in NO-induced apoptosis.

• Applied Biological Chemistry
• /
• v.43 no.3
• /
• pp.190-195
• /
• 2000

Tolaasin is a peptide toxin produced by Pseudomonas tolaasii and causes a brown blotch disease forming brown, slightly sunken spots and blotches on the cultivated mushrooms. It is a lipodepsipeptide consisting of 18 amino acids and its molecular mass is 1,985 Da. It forms a pore in plasma membranes, resulting in the disruption of membranes of fungal, bacterial, plant, and animal cells as well as mushroom tissue. In order to measure the toxicity of tolaasin, erythrocytes of blood were used to evaluate the tolaasin-induced hemolysis. Hemolytic activity of tolaasin was measured by observing the absorbance change either at 420 nm, representing the release of hemoglobins from red blood cells(RBCs), or at 600 nm, representing the density of residual cells. The hemolytic activity of culture-extract of P. tolaasii increased at early-stationary phase of growth and was maximal at late stationary phase. The hemolytic activity of tolaasin appeared high in the RBCs of dog and rat. The RBCs of rabbit and hen were less susceptible to tolaasin. The effects of various cations were also measured. $Cd^{2+}$ and $La^{3+}$. as well as $Zn^{2+}$ appeared inhibitory to the tolaasin-induced hemolysis. The effects of various anions on tolaasin-induced hemolysis were measured and carbonate showed the greatest inhibition to the hemolysis. However, phosphate stimulated the tolaasin-induced hemolysis and no effects were observed by chloride and nitrate.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.35 no.6
• /
• pp.545-550
• /
• 2002

A hemolysin producing bacterial strain which belong to Vibrio species was isolated from the Kum River estuary. In the process of identification, the strain did not show characteristics of known Vibrio species; thus, the strain was designated as Vibrio sp, E10 (V. kunsan) tentatively and further identification study was carried out by comparing its bacteriological characteristics. Morphologically Vibrio sp, E10 was comma shaped rod with a polar flagellium. Clear hemolysis zones were observed with the strain against human and sheep blood agar. Hemollytic toxicity was confirmed by strong vascular Permeability and fatal toxicity against mouse was also observed. Therefore the strain was a pathogenic vibrio. Growth conditions for Vibrio sp. E10 were ranged salinity of 0$\~$$4.5\%$, pH of 6.2$\~$9.2, temperature of 14$\~$42$^{\circ}C$, respectively, 16S rDNA partial sequence of Vibrio sp, E10 showed $99\%$ homology with dozens of V. cholerae species including V, cholerae El Tor N16961 and V, snmisnfus ATCC 33653T. This strain belonged to Proteobacteria; gamma subdivision; Vibrionacea: Vibrio. But, among knorn Vibrio species no identical styains were found when using automatic bacteria identification system ($MicroLog^{TM}$system, release 4.0, Biolog Inc., USA) which evaluated the ability of metabolizing 95 kinds of carbon and nitrogen sources. Vibrio sp, E10 showed 18 and 11 different responses as compared to V. mimicus and V, cholerae, respectively.

• Journal of Food Hygiene and Safety
• /
• v.35 no.6
• /
• pp.535-543
• /
• 2020

In addition to the ubiquitous roles of cellular RNA in genetic regulations, gene expression and phenotypic variations in response to environmental cues and chemotactic signals, the regulatory roles of a new type of RNA called extracellular RNAs (exRNAs) are an up-and-coming area of research interest. exRNA is transported outside the cell through membrane blebs known as membrane vesicles or extracellular vesicles (EVs). EV formation is predominant and conserved among all microbial forms, including prokaryotes, eukaryotes, and archaea. This review will focus on the three major topics concerning bacterially derived exRNAs, i.e., 1) the discovery of exRNA and influence of extraneous RNA over bacterial gene regulations, 2) the known secretion mechanism for the release of exRNA, and 3) the possible applications that can be devised with these exRNA secreted by different gram-negative and gram-positive bacteria. Further, this review will also provide an opinion on exRNA- and EV-derived applications such as the species-specific exRNA markers for diagnostics and the possible roles of exRNA in probiotics and the epigenetic regulations of the gut microbiome.

• Research in Plant Disease
• /
• v.28 no.1
• /
• pp.1-18
• /
• 2022

Volatiles exist ubiquitously in nature. Volatile compounds produced by plants and microorganisms confer inter-kingdom and intra-kingdom communications. Autoinducer signaling molecules from contact-based chemical communication, such as bacterial quorum sensing, are relayed through short distances. By contrast, biogenic volatiles derived from plant-microbe interactions generate long-distance (>20 cm) alarm signals for sensing harmful microorganisms. In this review, we discuss prior work on volatile compound-mediated diagnosis of plant diseases, and the use of volatile packaging and dispensing approaches for the biological control of fungi, bacteria, and viruses. In this regard, recent developments on technologies to analyze and detect microbial volatile compounds are introduced. Furthermore, we survey the chemical encapsulation, slow-release, and bio-nano techniques for volatile formulation and delivery that are expected to overcome limitations in the application of biogenic volatiles to modern agriculture. Collectively, technological advances in volatile compound detection, packaging, and delivery provide great potential for the implementation of ecologically-sound plant disease management strategies. We hope that this review will help farmers and young scientists understand the nature of microbial volatile compounds, and shift paradigms on disease diagnosis and management to aromatic (volatile-based) agriculture.

• Restorative Dentistry and Endodontics
• /
• v.25 no.4
• /
• pp.561-574
• /
• 2000

Poly-P has been used to prevent decomposition of foods and has been shown to have inhibitory effect on the growth of gram positive bacteria. The purpose of this study was to evaluate the effect of poly-P on the growth of Porphyromonas endodontalis, a gram negative obligate anaerobic rod, endodontopathic bacterium. P. endodontalis ATCC 35406 was in BHI broth containing hemin and vitamin K with or without poly-P. Inhibitory effect of each poly-P which was added at the beginning(lag phase) or during(exponential phase) the culture, MIC(minimum inhibitory concentration) was determined by measuring the optical density of the bacterial cell at 540nm. Viable cell counts were measured to determined whether poly-P has a bactericidal effect. Leakage of intracellular nucleotides from P. endodontalis was determined at 260nm and morphological change of P. endodontalis was observed under the TEM(transmission electron microscope). Binding of 32P-labeled poly-P to P. endodontalis was examined. SDS-polyacrylamide gel electrophoresis and zymography were performed to observe the changes in protein and enzyme profiles of P. endodontalis, respectively. The results from this study were as follows : 1. The minimal inhibitory concentration(MIC) of poly-P to P. endodontalis appeared to be 0.04~0.05%. 2. Poly-P added to the P. endodontalis culture during the exponential phase of P. endodontalis was as much effective as poly-P added at the begining of the culture, suggesting that the antibacterial effect of poly-P is not much dependent on the initial inoculum size of P. endodontalis. 3. Poly-P are bactericidal to P. endodontalis, demonstrating the decrease of the viable cell counts. 4. Intracellular nucleotide release from the P. endodontalis, was not increased in the presence of poly-P and was not reversed by the addition of divalent cations like $Ca^{2+}$ and $Mg^{2-}$. 5. Under the TEM, it was observed that fine electro-dense materials were prominent in the poly-P grown P. endodontalis, appearing locally in the cell, and the materials were more abundant and more dispersed in the cell as the incubation time with poly-P increased. In addition, highly electron dense granules accumulated in many poly-P grown cells, most of which were atypical in their shape. 6. Binding of 32P-labeled poly-P to P. endodontalis appeared to be 32.8 and 45.5 and 53.4% at 30 minutes, 1 hours and 2 hours, respectively. 7. In the presence of poly-P. the synthesis of proteins with apparent molecular masses of 25, 27, 35, 45 was lost or drastically decreased whereas expression of a protein with an apparent molecular mass of 75 was elevated. 8. Proteolytic activity of P. endodontalis was decreased by poly-P. The overall results suggest that use of poly-P may affect the growth of P. endodontalis, and the anti-bacterial activity of poly-P seems largely bactericidal. Changes in shape, protein expression, and proteolytic activity of P. endodontalis by poly-P may be directly and indirectly attributed to the antibacterial effect of poly-P. Further studies will be needed to confirm the effect of poly-P.

• Tuberculosis and Respiratory Diseases
• /
• v.41 no.4
• /
• pp.319-327
• /
• 1994

Background: The pathogenetic mechanism of adult respiratory distress syndrome(ARDS) is not clearly defined yet, but it is well known that increased pulmonary capillary permeabilty is characteristic feature of ARDS. The increased alveolar-capillary permeability is usually preceded by damage of pulmonary artery endothelial cells. The released enzymes and oxygen free radicals from the activated neutrophils seem to play a predominant role in endothelial cell cytotoxicity. The activated neutrophils, however, probably are not the sole contributing factor in this type of damage because many cases of ARDS have been reported in severe neutropenia. Bacterial endotoxin perse and/or oxygen free radicals released from endothelial cells are suggested to be possible factors that contribute to the development of ARDS. The purpose of this study is to investigate the direct cytotoxicity of endotoxin and the role of oxygen free radicals released from the endothelial cells in endotoxin-induced endothelial cell cytotoxicity. Methods: First, to investigate whether endotoxin is cytotoxic to HUVE by itself, various doses of endotoxin were added to culture medium and cytotoxicity was measured. Second, to evaluate the possible role of oxygen free radical in endotoxin-induced HUVE cytotoxicity, various antioxidants were added on the endotoxin-induced HUVE cytotoxicity and cytotoxicity was measured. Third, to verify the release of oxygen free radicals from HUVE, the concentrations of hydrogen peroxide in the endotoxin-treated culture supernatant were measured. Finally, to observe the cytotoxic effect of hydrogen peroxide, HUVE cytotoxicity in the presence of various doses of hydrogen peroxide was measured. The fourth generations of subcultured HUVE from primary culture were used. The cell cytotoxicity was quantified by the chromium-51 release assay. Results: 1) Endotoxin alone showed HUVE cytotoxicity in a dose-dependent fashion. 2) Endotoxin-induced HUVE cytotoxicity was significantly attenuated by the pretreatment of catalase and DMTU. 3) Hydrogen peroxide was released from HUVE after endotoxin treatment in a dose-dependent fashion. 4) Exogenous hydrogen peroxide also showed HUVE cytotoxicity in a dose-dependent fashion. Conclusion: These results suggest that endotoxin alone can directly injure HUVE, and, oxygen-free radicals released from HUVE in response to endotoxin may also participate in the endotoxin-induced HUVE cytotoxicity.

• Journal of Mushroom
• /
• v.17 no.2
• /
• pp.64-69
• /
• 2019

The present study was conducted to investigate the synergistic effects caused by single and co-inoculation of the phosphate solubilizing bacteria (PSB), Paraburkholderia phenazinium YH3 and Paraburkholderia metrosideri YH4. Phosphate solubilization was assessed by measuring the phosphorus contents for 7 days in a single and co-inoculation medium. Co-inoculation of the two strains was found to release the highest content of soluble phosphorus ($1,250{\mu}g\;mL^{-1}$) into the medium, followed by the single inoculation of P. metrosideri YH4 ($1196.59{\mu}g\;mL^{-1}$) and P. phenazinium YH3 ($994.34{\mu}g\;mL^{-1}$). The highest pH reduction, organic acid production and glucose consumption was also observed in the co-inoculation medium of the two strains. A plant growth promotion bioassay revealed that co-inoculation with the two strains enhanced the growth of romaine lettuce more than single inoculation with either of the two strains (28.5% for leaf and 16.6% for root). Although there was no significant difference between single and co-inoculation of bacterial strains in terms of phosphorous release and plant growth, the synergistic effects of co-inoculation with PSB could be beneficial for crop growth.