• The Plant Pathology Journal
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• v.26 no.4
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• pp.313-320
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• 2010

Genetic instability of the rice blast fungus Magnaporthe oryzae has been suggested as a major factor underlying the rapid breakdown of host resistance in the field. However, little information is available on the mechanism of genetic instability. In this study, we assessed the stability of repetitive DNA elements and several key phenotypic traits important for pathogenesis after serially transferring two isolates though rice plants and an artificial medium. Using isolate 70-15, we obtained a total of 176 single-spore isolates from 10 successive rounds of culturing on artificial medium. Another 20 isolates were obtained from germ tubes formed at the basal and apical cells of 10 three-celled conidia. Additionally, 60 isolates were obtained from isolate KJ201 after serial transfers through rice plants and an artificial medium. No apparent differences in phenotypes, including mycelial growth, conidial morphologies, conidiation, conidial germination, appressorium formation, and virulence, or in DNA fingerprints using MGR586, MAGGY, Pot2, LINE, MG-SINE and PWL2 as probes were observed among isolates from the same parent isolate. Southern hybridization and sequence analysis of two avirulence genes, AVR-Pita1 and AVR-Pikm, showed that both genes were also maintained stably during 10 successive generations on medium and plants. However, one reversible loss of restriction fragments was found in the telomere-linked helicase gene (TLH1) family, suggesting some telomere regions may be more unstable than the rest of the genome. Taken together, our results suggest that phenotype and genotype of M. oryzae isolates do not noticeably change, at least up to 10 successive generations on a cultural medium and in host plants.

• Tuberculosis and Respiratory Diseases
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• v.47 no.2
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• pp.172-183
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• 1999

Background: Nitric oxide is a short-lived effector molecule derived from L-arginine by the nitric oxide synthase(NOS). Nitric oxide plays a role in a number of physiologic and pathophysiologic functions including host defense, edema formation, and regulation of smooth muscle tone. Some kinds of cells including macrophage are known to produce large quantities of nitric oxide in response to inflammatory stimuli such as interleukin-$1\beta$(IL-$1\beta$), tumor necrosis factor-$\alpha$(TNF-$\alpha$), interferon-$\gamma$(IFN-$\gamma$) and lipopolysaccharide(LPS). Reactive oxygen species are also known to be important in the pathogenesis of acute cell and tissue injury such as acute lung injury model Methods: Using the RA W264.7 cells, we have examined the ability of oxidant hydrogen peroxide($H_2O_2$) to stimulate nitric oxide production and inducible NOS mRNA expression. Also, we have examined the effects of NOS inhibitors and antioxidants on $H_2O_2$ induced nitric oxide production. Results: Stimulation of RAW264.7 cells with combinations of 100 ng/ml IL-$1\beta$, 100 ng/ml TNF-$\alpha$, and 100 U/ml IFN-$\gamma$ or 100 U/ml IFN-$\gamma$ and $1{\mu}g/ml$ LPS induced the synthesis of nitric oxide as measured by the oxidation products nitrite($NO_2^-$) and nitrate($NO_3^-$). Addition of $250 {\mu}M-2$ mM $H_2O_2$ to the cytokines significantly augmented the synthesis of $NO_2^-$ and $NO_3^-$(p<0.05). When cells were incubated with increasing concentrations of $H_2O_2$ in the presence of IL-$1\beta$, TNF-$\alpha$ and IFN-$\gamma$ at constant level, the synthesis of $NO_2^-$ and $NO_3^-$ was dose-dependently increased(p<0.05). $N^G$-nitro-L-arginine methyl ester(L-NAME), dose dependently, significantly inhibited the formation of $NO_2^-$ and $NO_3^-$ in cells stimulated with LPS, IFN-$\gamma$ and $H_2O_2$ at constant level(p<0.05). Catalase significantly inhibited the $H_2O_2$-induced augmentation of cytokine-induced $NO_2^-$ and $NO_3^-$ formation(p<0.05). But, boiled catalase did not produce a significant inhibition in comparison with the native enzyme. Another antioxidant 2-mercaptoethanol and orthophenanthroline dose-dependently suppressed $NO_2^-$ and $NO_3^-$ synthesis(p<0.05). Northern blotting demonstrated that H:02 synergistically stimulated the cytokine-induced iNOS mRNA expression in RA W264.7. Conclusion: These results suggest that $H_2O_2$ contributes to inflammatory process by augmenting the iNOS expression and nitric oxide synthesis induced by cytokines.

• Journal of Life Science
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• v.30 no.2
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• pp.113-121
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• 2020

Macrophages are initiators for regulating a host's defenses to eliminate pathogens and trigger tissue repair. Macrophages are classified into two types: classically (M1) activated macrophages and alternatively (M2) activated macrophages. M1-phenotype macrophages directly or indirectly kill infectious organisms and tumor cells via pro-inflammatory responses, whereas M2-phenotype macrophages remodel wounded tissue through anti-inflammatory responses. In this paper, we investigated how Phellinus linteus hot water extract passed from Diaion HP-20 resin (PLEP) regulates polarization of M1-like or M2-like macrophages in human THP-1 cells. PLEP did not have cytotoxicity at a high concentration of 300 ㎍/ml. We observed morphological alteration of the THP-1 cells, which are stimulated by PLEP, LPS/INF-γ (M1 stimulators) or IL-4/IL13 (M2 stimulators). PLEP exposure induced morphology contiguous with LPS/INF-γ. qPCR was also performed to determine whether PLEP influences M1 or M2 polarization-related genes. M1-phenotype macrophage-specific genes, such as TNF-α, IL-1β, IL-6, IL-8, CXCL10 and CCR7, were enhanced by PLEP in a dose-dependent manner similar to LPS/INF-γ. Conversely, M2-phenotype-specific genes, such as MRC-1, DC-SIGN, CCL17 and CCL22, were suppressed by PLEP. PLEP also significantly up-regulated secretory inflammation cytokines related to M1 polarization of macrophages, including TNFα, IL-1β and IL-6, which was similar to the gene expression. Further, MAPK and NF-κB signaling were increased by treatment with PLEP, resulting in enhancement of cytokine secretion. PLEP might therefore be used as a promising booster of pro-inflammatory responses through M1 polarization of human THP-1 cells.

• Journal of Microbiology and Biotechnology
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• v.17 no.8
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• pp.1353-1360
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• 2007

Three csp-like genes were identified in the Corynebacterium glutamicum genome and designated cspA, cspB, and cspA2. The genes cspA and cspA2 encode proteins, comprising of 67 amino acid residues, respectively. They share 83% identity with each other. Identity of those proteins with Escherichia coli Csp proteins was near 50%. The cspB gene encodes a protein composed of 127 amino acids, which has 40% and 35% sequence identity with CspA and CspA2, respectively, especially at its N-terminal region. Analysis of the gene expression profiles was done using transcriptional cat fusion, which identified not only active expression of the three genes at the physiological growth temperature of $30^{\circ}C$ but also growth phase-dependent expression with the highest activity at late log phase. The promoters of cspA and cspA2 were more active than that of cspB. The expression of the two genes increased by 30% after a temperature downshift to $15^{\circ}C$, and such stimulation was more evident in the late growth phase. In addition, the cspA gene appeared to show DNA-binding activity in vivo, and the activity increased at lower temperatures. Interestingly, the presence of cspA in multicopy hindered the growth of the host C. glutamicum cells at $20^{\circ}C$, but not at $30^{\circ}C$. Altogether, these data suggest that cspA, cspB, and cspA2 perform functions related to cold shock as well as normal cellular physiology. Moreover, CspA and its ortholog CspA2 may perform additional functions as a transcriptional regulator.

• Molecules and Cells
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• v.26 no.2
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• pp.131-139
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• 2008

Expression of the seven open reading frames (ORFs) of single-stranded DNA Curtoviruses such as Beet curly top virus (BCTV) and Beet severe curly top virus (BSCTV) is driven by a bi-directional promoter. To investigate this bidirectional promoter activity with respect to viral late gene expression, transgenic Arabidopsis plants expressing a GUS reporter gene under the control of either the BCTV or BSCTV bi-directional promoter were constructed. Transgenic plants harboring constructs showed higher expression levels when the promoter of the less virulent BCTV was used than when the promoter of the more virulent BSCTV was used. In transgenic seedlings, the reporter gene constructs were expressed primarily in actively dividing tissues such as root tips and apical meristems. As the transgenic plants matured, reporter gene expression diminished but viral infection of mature transgenic plants restored reporter gene expression, particularly in transgenic plants containing BCTV virion-sense gene promoter constructs. A 30 base pair conserved late element (CLE) motif was identified that was present three times in tandem in the BCTV promoter and once in that of BSCTV. Progressive deletion of these repeats from the BCTV promoter resulted in decreased reporter gene expression, but BSCTV promoters in which one or two extra copies of this motif were inserted did not exhibit increased late gene promoter activity. These results demonstrate that Curtovirus late gene expression by virion-sense promoters depends on the developmental stage of the host plant as well as on the number of CLE motifs present in the promoter.

• Journal of Microbiology and Biotechnology
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• v.18 no.3
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• pp.585-590
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• 2008

Human tropic Porcine Endogenous Retroviruses (PERVs) are the major concern in zoonosis for xenotransplantation because PERVs cannot be eliminated by specific pathogen-free breeding. Recently, a PERV A/C recombinant with PERV-C bearing PERV-A gp70 showed a higher infectivity (approximately 500-fold) to human cells than PERV-A. Additionally, the chance of recombination between PERVs and HERVs is frequently stated as another risk of xenografting. Overcoming zoonotic barriers in xenotransplantation is more complicated by recombination. To achieve successful xenotransplantation, studies on the recombination in PERVs are important. Here, we cloned and sequenced proviral PERV env sequences from pig gDNAs to analyze natural recombination. The envelope is the most important element in retroviruses as a pivotal determinant of host tropisms. As a result, a total of 164 PERV envelope genes were cloned from pigs (four conventional pigs and two miniature pigs). Distribution analysis and recombination analysis of PERVs were performed. Among them, five A/B recombinant clones were identified. Based on our analysis, we determined the minimum natural recombination frequency among PERVs to be 3%. Although a functional recombinant envelope clone was not found, our data evidently show that the recombination event among PERVs may occur naturally in pigs with a rather high possibility.

• Applied Microscopy
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• v.10 no.1_2
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• pp.27-32
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• 1980

A case of cutaneous leishmaniasis developed in a 48 year old Korean male who returned from middle east was studied by light and electron microscopic observations. Light microscopically, the lesion consisted of heavy chronic ill-defined granulomatous inflammation involving entire thickness of the dermis, composed of mainly histiocytic and small mononuclear cell infiltrations without evidence of necrosis or giant cell formation. Giemsa staining revealed numerous intracellular micro-organisms within histiocytes, showing dark stained central dot surrounded by light stained cytoplasm. Electron microscopically, the organisms were observed mostly ovoid in shape and frequently binary mitotic features within the host cells. follicle consisted of double unit membranes and microtubules, which are immediately below these membrnae. A long kinetoplast was noted within a very elongated mitochondrion at the center of the organisms and a flagella rose in front of the kineoplast but ended within the cytoplasm. Large numbers of free ribosomes, occasional Golgi complex and SER were also noted, but RER was seldom found. These ultrastructural features corresponded to promastigote stage of Leishmania tropica. In principle, leishmaniasis is a tropical disease and can not be found in temperate zone. However, travel to mideast by many Koreans may contract this disease while they are in endemic regions.

• Korean Journal of Clinical Laboratory Science
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• v.41 no.1
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• pp.42-46
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• 2009

Unlike most bacteria, Treponema pallidum subspecies cannot be readily isolated or sustained in cell culture for numerous generations. In korea, two non treponemal tests are currently considered as standard; the VDRL slide test and RPR card test. These tests are based on an antigen composed of an alcoholic solution containing measured amount of cardiolipin, cholesterol, and sufficient purified lecithin to produce reactivity. The nontreponemal reagin tests measure immunoglobulin M (IgM) and IgG to lipoidal material released from damaged host cells as well as to lipoprotein-like material and possibly by cardiolipin released from the treponemes. The object of the evaluation was to evaluate the performance of the Mediace RPR kit on the automated biochemistry analyzer system as a method for screen method of syphilis as well as to identify BFP possibility. For evaluation of routine screening test, a total 2,380 specimens tested by Mediace RPR from 28th Oct, 2007 to 22th Feb, 2008. For evaluation of BFP possiblility, we measured samples which have potential BFP reaction in Syphilis test such as ANA (anti-nuclear antibody) positive (135 samples), CRP (C-reactive protein) positive (100 samples), RF (Rheumatoid factor) positive (26 samples), and other potential BFP cases (17 samples) including total 278 samples. These samples were tested quantitative test Mediace RPR with Hitachi 7600 P module. For comparison with current manual test, VDRL slide test were performed. Of these 2380 specimens, 2350 were negative, 30 were positive, and one were positive with TPHA. Both methods agreed for 2356 (98.9%) samples. Of the 30 samples showed positive results over 1.0 R.U, 6 samples showed positive results with VDRL test. Of these 6 samples, 1 samples showed positive with TPHA test. The combination of the Automated Biochemistry analyzer and VDRL test for retest can be increase efficiency of syphilis screening test.

• Korean Journal of Environmental Agriculture
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• v.34 no.2
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• pp.139-148
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• 2015

BACKGROUND: The aim of this study was to isolate and identify algicidal bacterium that tends to kill the toxic dinoflagellate Alexandrium catenella, and to determine the algicidal activity and algicidal range of algicide. METHODS AND RESULTS: Among of algicidal bacteria isolated in this study, NH-3 isolate was the strongest algicidal activity against A. catenella. NH-3 isolate was identified on the basis of biochemical characteristics and analysis of 16S rRNA gene sequences. The NH-3 isolate showed over 99% homology with Arthrobacter oxydans, and was designated as Arthrobacter sp. NH-3. The optimal culture conditions were $25^{\circ}C$, initial pH 7.0, and 2.0% (w/v) NaCl concentration. The algicidal activity of Arthrobacter sp. NH-3 was significantly increased to maximum value in the late of logarithmic phase. Arthrobacter sp. NH-3 showed algicidal activity through indirect attack, which excreted active substance into the culture filtrate. When 10% culture filtrate of NH-3 was applied to A. catenella, 100% of algal cells were destroyed within 30 h. In addition, the algicidal activities were increased in dose and time dependent manners. The pure algicide was isolated from the ethyl acetate extract of the culture filtrate of NH-3 by using silica gel column chromatography and high performance liquid chromatography (HPLC). We investigated the algicidal activity of this algicide on the growth of harmful algal bloom (HAB) species, including A. catenella. As a result, it showed algicidal activity against several HAB species at a concentration of $100{\mu}g/mL$ and had a relatively wide host range. CONCLUSION: Taken together, our results suggest that Arthrobacter sp. NH-3 and its algicide could be a candidate for controlling of toxic and harmful algal blooms.

• Molecules and Cells
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• v.40 no.4
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• pp.262-270
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• 2017

MicroRNAs (miRNAs) are single-stranded, small RNAs (21-23 nucleotides) that function in gene silencing and translational inhibition via the RNA interference mechanism. Most miRNAs originate from host genomic regions, such as intergenic regions, introns, exons, and transposable elements (TEs). Here, we focused on the palindromic structure of medium reiteration frequencies (MERs), which are similar to precursor miRNAs. Five MER consensus sequences (MER5A1, MER53, MER81, MER91C, and MER117) were matched with paralogous transcripts predicted to be precursor miRNAs in the horse genome (equCab2) and located in either intergenic regions or introns. The MER5A1, MER53, and MER91C sequences obtained from RepeatMasker were matched with the eca-miR-544b, eca-miR-1302, and eca-miR-652 precursor sequences derived from Ensembl transcript database, respectively. Each precursor form was anticipated to yield two mature forms, and we confirmed miRNA expression in six different tissues (cerebrum, cerebellum, lung, spleen, adrenal gland, and duodenum) of one thoroughbred horse. MER5A1-derived miRNAs generally showed significantly higher expression in the lung than in other tissues. MER91C-derived miRNA-5p also showed significantly higher expression in the duodenum than in other tissues (cerebellum, lung, spleen, and adrenal gland). The MER117-overlapped expressed sequence tag generated polycistronic miRNAs, which showed higher expression in the duodenum than other tissues. These data indicate that horse MER transposons encode miRNAs that are expressed in several tissues and are thought to have biological functions.