• The Plant Pathology Journal
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• v.15 no.1
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• pp.53-56
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• 1999

Fifty-three isolates of Fusarium graminearum were obtained from corn and barley samples in several provinces of Korea. Gas chromatography-mass spectrometric analysis of trichothecenes produced by these isolates revealed that 37 and 16 isolates were nivalenol (NIV)- and deoxynivalenol (DON)-chemotypes, respectively. Two hundred and seventy-five nitrate-nonutilizing (nit) mutants were obtained from the isolates. Of these mutants, 187 were identified as nit1, nit3, or NitM, but 88 could not be identified as one of these classes. The highest frequency of nit mutant was nit1 (65%), followed by nit3 (20%) and NitM (15%). Higher frequency of NitM was observed in DON-chemotypes than in NIV-chemotypes. The mutants were used for vegetative compatibility group (VCG) analysis by examining heterokaryosis using complementary mutant pairs. No heterokaryon formation was observed among all 1,248 pairwise combinations, suggesting that all isolates tested belong to different VCGs. Higher frequency of self-incompatibility was observed in NIV-chemotypes than in DON-chemotypes. These results suggest that the like-lihood of asexual genetic recombination may be very low I F. graminearum under the field condition.

• Journal of Life Science
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• v.25 no.9
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• pp.1051-1058
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• 2015

Citrus mutant fruits were induced by irradiation of citrus budsticks with 120 Gy of cobalt (⁶⁰CO) gamma irradiation. The citrus mutant inhibited the growth and induced apoptosis in various human cancer cells, including A549, HepG2, HCT116, MCF-7, and Hela. The results of a trypan blue exclusion assay showed that citrus mutant fruits exhibited excellent antiproliferation activity in various human cancer cells and low cytotoxicity in normal 16HBE140- and CHANG cells. In addition, the cell death induced by the citrus mutant fruits was associated with an increased population of cells in sub-G1 phase, and it caused DNA fragmentation in human lung adenocarcinoma A549 and hepatocellular carcinoma HepG2 cells. It also up-regulated the amount of cellular nitric oxide (NO^•) produced as a result of nitric oxide synthase (NOS) activation and suppressed the inhibitor of apoptosis protein (IAP) family in A549 and HepG2 cells. These findings indicate that the citrus mutant fruits activates the NO^•-mediated apoptotic pathway in A549 and HepG2 cells. It may merit further investigation as a potential chemotherapeutic and chemopreventive agent for the treatment of various types of cancer cells. The results provide important major new insights into the mechanisms of the anticancer activity of citrus mutant fruits.

• Korean Journal of Breeding Science
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• v.40 no.3
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• pp.303-307
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• 2008

We bred a new green-kerneled glutinous rice variety that can be cultivated in the whole area of Korea, because only one native green-kerneled glutinous rice cultivar, "Saengdongchalbyeo", has been cultivated in the southern coastal area due to its late heading. The seeds of "Saengdongchalbyeo" were irradiated with 200 Gy of gamma ray in 1995. A promising mutant variety, "Nogwonchalbyeo" ("Wonnong 17") was selected through line selection and regional yield trials. In particular, the new variety revealed at the earlier mid of August compared to that of "Saengdongchalbyeo", the early of September, and it was considerably tolerant to a field lodging due to its shortened culm length. Also, "Nogwonchalbyeo" had a higher ripened grain ratio and 1,000 grain weight compared to the original variety. The brown grain yield of the new variety was about 5.40 MT/ha, which was 11.3% higher than that of the original variety, in the regional yield trials at 3 different fields during 2000~2001. The brown and milled grains of the new rice variety contained 20 to 65% higher amount of total amino acids, respectively than that of the original and two checks. For chlorophyll -a, -b and total chlorophyll, the new variety showed nearly two-fold higher than the checks, and for the carotenoid, it had 5.3 - 7.6 times higher amount. These results showed that the new variety can be cultivated as a special green-kerneled glutinous rice with high functional compounds.

• Biomolecules & Therapeutics
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• v.21 no.2
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• pp.97-106
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• 2013

Chronic hepatitis C virus (HCV) infection is responsible for the development of liver cirrhosis and hepatocellular carcinoma. HCV core protein plays not only a structural role in the virion morphogenesis by encapsidating a virus RNA genome but also a non-structural role in HCV-induced pathogenesis by blocking innate immunity. Especially, it has been shown to regulate JAK-STAT signaling pathway through its direct interaction with Janus kinase (JAK) via its proline-rich JAK-binding motif ($^{79}{\underline{P}}GY{\underline{P}}WP^{84}$). However, little is known about the physiological significance of this HCV core-JAK association in the context of the virus life cycle. In order to gain an insight, a mutant HCV genome (J6/JFH1-79A82A) was constructed to express the mutant core with a defective JAK-binding motif ($^{79}{\underline{A}}GY{\underline{A}}WP^{84}$) using an HCV genotype 2a infectious clone (J6/JFH1). When this mutant HCV genome was introduced into hepatocarcinoma cells, it was found to be severely impaired in its ability to produce infectious viruses in spite of its robust RNA genome replication. Taken together, all these results suggest an essential requirement of HCV core-JAK protein interaction for efficient production of infectious viruses and the potential of using core-JAK blockers as a new anti-HCV therapy.

• Journal of Microbiology and Biotechnology
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• v.12 no.2
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• pp.242-248
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• 2002

Previously, it was reported that the nonhomologous C-terminal regions of the D-hydantoinases are nonessential for catalysis, but affect the oligomeric structure of the enzyme [3]. In an effort to further confirm the above observation, the C-terminal region-inserted enzyme was constructed by attaching a peptide (22 residues) at the C-terminal of the D-hydantoinase from Bacillus thermocatenulatus GH2, and its structural and biochemical properties were compared with both the wild-type and C-terminal region-truncated enzymes. As a result, native tetrameric D-hydantoinase was dimerized as the truncated enzyme, and the inserted mutant with a new sequence was expressed as a catalytically active form in E. coli. Expression level of the inserted and truncated enzymes were found to be significantly increased compared to the level of the wild-type enzyme, and this appears to be due to the reduced toxic effect of the mutant enzymes on host cells. Dimerized enzymes exhibited increased thermo- and pH stabilities considerably when compared with the corresponding wild-type enzyme. Comparison of the substrate specificity between the mutant and wild-type enzymes suggests that the substrate specificity of the D-hydantoinase is closely linked with the oligomeric structure.

• The Plant Pathology Journal
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• v.32 no.3
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• pp.266-272
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• 2016

A bacterial tyrosine sulfotransferase, RaxST, is required for activation of rice XA21-mediated immunity, and it catalyzes sulfation of tyrosine residues of Omp1X and RaxX in Xanthomonas oryzae pv. oryzae, a causal agent of bacterial blight in rice. Although RaxST is biochemically well-characterized, biological functions of tyrosine sulfation have not been fully elucidated. We compared protein expression patterns between the wildtype and a raxST knockout mutant using shotgun proteomic analysis. Forty nine proteins displayed a more than 1.5-fold difference in their expression between the wildtype and the mutant strains. Clusters of orthologous groups analysis revealed that proteins involved in cell motility were most abundant, and phenotypic observation also showed that the twitching motility of the mutant was dramatically changed. These results indicate that tyrosine sulfation by RaxST is essential for Xoo movement, and they provide new insights into the biological roles of RaxST in cellular processes.

• Journal of Sericultural and Entomological Science
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• v.35 no.2
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• pp.93-99
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• 1993

Studies were carried out to investigate physiological and biochemical analysis of recessive lethal mutant "nmn" and to observe the cuticle formation and dermal gland. All nmn homozygous larvae continued to eat a few mulberry leaves, and died without entering into molt. In case of artificial hatching, eggs had a higher nmn individual segregation ratio than in hibernating eggs. The percentage of nmn individuals with the hatching days was alike during 3days period. As a result of histological observation, nmn mutants dermal gland was different from normal dermal gland in form and size. Normal was formed new cuticle in the middle of the molting, but not in nmn mutant. Total protein content in haemolymph of the normal larva was more than that of nmn smutant and there was a difference between normal and nmn mutant protein components.omponents.

• Mycobiology
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• v.46 no.4
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• pp.429-439
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• 2018

To develop a convenient promoter analysis system for fungi, a null-pigment mutant (NPG) of Aspergillus nidulans was used with the 4'-phosphopantetheinyl transferase (PPTase) gene, npgA, which restores the normal pigmentation in A. nidulans, as a new reporter gene. The functional organization of serially deleted promoter regions of the A. nidulans trpC gene and the Cryphonectria parasitica crp gene in filamentous fungi was representatively investigated to establish a novel fungal promoter assay system that depends on color complementation of the NPG mutant with the PPTase npgA gene. Several promoter regions of the trpC and crp genes were fused to the npgA gene containing the 1,034-bp open reading frame and the 966-bp 3' downstream region from the TAA, and the constructed fusions were introduced into the NPG mutant in A. nidulans to evaluate color recovery due to the transcriptional activity of the sequence elements. Serial deletion of the trpC and crp promoter regions in this PPTase reporter assay system reaffirmed results in previous reports by using the fungal transformation step without a laborious verification process. This approach suggests a more rapid and convenient system than conventional analyses for fungal gene expression studies.

• The Plant Pathology Journal
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• v.16 no.3
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• pp.151-155
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• 2000

A cDNA (Oslls1) encoding Lls1-homologue of maize was isolated from cDNA library of rice (Oryza sativa cv. Ilpum). The 2,138 bp of full length Oslls1 clone contains an open reading frame of 1,623 nucleotides encoding 575 amino acid residues. The deduced amino acid sequence of Oslls1 has a high level of homology with chlorophyll a oxygenases of Arabidopsis thaliana (67%) and Marchantia polymorpha (65%). Southern blot analysis of genomic DNA indicates the existence of a small gene family for Oslls1 in the rice genome. The expression of Oslls1 mRNA was induced in leaves and germinating seeds. Treatment of $H_2O$$_2$significantly down-regulated Oslls1 expression. The expression of Oslls1 mRNA was consititutively down-regulated in the blm, a rice mutant exhibiting spontaneous necrotic lesions. These results suggest that this Oslls1 gene may be involved incell death mechanisms in the blm mutant of rice.

• Journal of Microbiology and Biotechnology
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• v.26 no.5
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• pp.959-966
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• 2016

Chlorophyll synthase (ChlG) and bacteriochlorophyll synthase (BchG) have a high degree of substrate specificity. The BchG mutant of Rhodobacter sphaeroides, BG1 strain, is photosynthetically incompetent. When BG1 harboring chlG of Synechocystis sp. PCC 6803 was cultured photoheterotrophically, colonies arose at a frequency of approximately 10^-8. All the suppressor mutants were determined to have the same mutational change, ChlG_I44F. The mutated enzyme ChlG_I44F showed BchG activity. Remarkably, BchG_F28I, which has the substitution of F at the corresponding 28^th residue to I, showed ChlG activity. The K_m values of ChlG_I44F and BchG_F28I for their original substrates, chlorophyllide (Chlide) a and bacteriochlorophyllide (Bchlide) a, respectively, were not affected by the mutations, but the K_m values of ChlG_I44F and BchG_F28I for the new substrates Bchlide a and Chlide a, respectively, were more than 10-fold larger than those for their original substrates, suggesting the lower affinities for new substrates. Taken together, I44 and F28 are important for the substrate specificities of ChlG and BchG, respectively. The BchG activity of ChlG_I44F and the ChlG activity of BchG_F28I further suggest that ChlG and BchG are evolutionarily related enzymes.