• Proceedings of the Zoological Society Korea Conference
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• 2003.08a
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• pp.211.3-211
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• 2003

No Abstract, See Full Text

• Proceedings of the Microbiological Society of Korea Conference
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• 2002.10a
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• pp.162-172
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• 2002

Schizosaccharomyces pombe is suited for the study of cytokinesis as it divides by forming a septum in the middle of the cell at the end of mitosis. To enhance our understanding of the cytokinesis, we have carried out a genetic screen for temperature-sensitive S. pombe mutants that show defects in septum formation and cell division. Here we present the isolation and characterization of a new temperature-sensitive mutant, sun1(septum uncontrolled), which undergoes uncontrolled septation during cell division cycle at restrictive temperature $(37^{\circ}C)$. In sun1 mutant, actin ring and septum are positioned at random locations and angles, and nuclear division cycle continues. These observations suggest that the sun] gene product is required for the proper placement of the actin ring as well as precise septation. The sun] mutant is monogenic recessive mutation unlinked to previously known various cdc genes of S. pombe. In a screen for $sunl^+$ gene to complement the sun] mutant, we have cloned a gene, $susl^+$(suppressor of sun1 mutant), that encodes a protein of 689 amino acids. The predicted amino acid sequence of $susl^+$ gene is similar to the human hMadlp and Saccharomyces cerevisiae Mad1p, a component of the spindle checkpoint in eukaryotic cells. The null mutant of $susl^+$ gene grows normally at various temperatures and has the increased sensitivity to anti-microtubule drug, while $susl^+$ mutant shows no sensitivity to microtubule destabilizing drugs. The putative S. pombe Sus1p directly interacts with S. pombe Mad2p in yeast two-hybrid assays. These data suggest that the newly isolated susr gene encodes S. pombe Mad1p and suppresses sun] mutant defective in controlled septation in a cell division cycle.

• Journal of the Korean Society of Food Science and Nutrition
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• v.33 no.6
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• pp.1017-1021
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• 2004

To isolate a mutant which overproduces threonine and tryptophan, mutants of Saccharomyces cerevisiae were screened after UV and EMS mutagenesis. Hydroxynorvaline, a Thr analogue was used for selection of a Thr-overproducing mutant after UV mutagenesis. Among 31 mutants, TC 5-1 was selected as the strain candidate, based on amino acid analysis. TC 5-1 was then treated by EMS mutagenesis for Trp overproduction. Eight mutants were selected using fluorotryptophan for Thr and Trp overproducing strains. Amino acid analysis results showed that TC 6-1 was the best strain since it had the highest amount of Thr and Trp among mutants.

• Journal of Photoscience
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• v.3 no.1
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• pp.23-28
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• 1996

To investigate the structure and function of photosystem I, cartridge mutagenesis technique was used to inactivate the psaB gene of photosystem I. From the screen, many strains which have potential defects in photosystem I were generated. Biochemical analysis revealed that B2, one of the mutant, had a reduced amount of chlorophyll. Electron transfer activitx from photosystem II to photosystem I as oxygen uptake was the rate of 64 % of wild type. Also B2 showed a decreased photosystem I activity when measured by 77 K fluorescence emission spectrum. Particularly, immunodetection analysis showed that the B2 had reduced amount of PsaA/PsaB, but a normal range of PsaC and PsaD. Here we present a photoheterotrophic mutant for psaB gene as a unique model strain for future study of structural/functional relationship and biogenesis of photosystem I.

• KSBB Journal
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• v.14 no.2
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• pp.235-240
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• 1999

Simple and rapid screening methods were developed to screen mutant strains of Trigonopsis variabilis ATCC10679 (TW). D-amino acid oxidase (D-AAO) from a mutant strain, T26, showed about 30% higher specific activity against cephalosporin C than from its wild type, TW. D-AAO genes from both TW and T26 strains were cloned and sequenced. There was one nucleotide changed from T to C at 811 position, resulting in an amino acid codon changed from Phe-258 to Ser-258.

• Biomolecules & Therapeutics
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• v.31 no.1
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• pp.48-58
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• 2023

Interferon regulatory factor 3 (IRF3) integrates both immunological and non-immunological inputs to control cell survival and death. Small GTPases are versatile functional switches that lie on the very upstream in signal transduction pathways, of which duration of activation is very transient. The large number of homologous proteins and the requirement for site-directed mutagenesis have hindered attempts to investigate the link between small GTPases and IRF3. Here, we constructed a constitutively active mutant expression library for small GTPase expression using Gibson assembly cloning. Small-scale screening identified multiple GTPases capable of promoting IRF3 phosphorylation. Intriguingly, 27 of 152 GTPases, including ARF1, RHEB, RHEBL1, and RAN, were found to increase IRF3 phosphorylation. Unbiased screening enabled us to investigate the sequence-activity relationship between the GTPases and IRF3. We found that the regulation of IRF3 by small GTPases was dependent on TBK1. Our work reveals the significant contribution of GTPases in IRF3 signaling and the potential role of IRF3 in GTPase function, providing a novel therapeutic approach against diseases with GTPase overexpression or active mutations, such as cancer.

• Applied Biological Chemistry
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• v.4
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• pp.11-16
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• 1963

(1) The 30 strains of Penicillia and the 52 strains of Aspergilli have been screened for their producibility of 5'-Phosphodiesterase, and Penicillium sclerotiorum 7321, Penicillium sp M-11 and Penicillium citrinum UV-mutant 2032-72 were selected as having high 5‘-Phosphodiesterase activity. (2) Using the wheat bran medium the 5‘-Phosphodiesterase production was reached at maximum state by the plate culture for 10 days at $30^{\circ}C$ (3) The optimum conditions of the 5'-Phosphodiesterase activity of Penicillium sclerotiorum 7321 and Penicillium sp M-11 were pH 4.0 at $62.5^{\circ}C$, while the optimum condition of the 5'-Phosphodiesterase activity of Penicillium citrinum UV-mutant 2032-72 was pH 5.0 at $50^{\circ}C$.

• Journal of Integrative Natural Science
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• v.4 no.2
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• pp.113-120
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• 2011

Brassinosteroids (BRs) are plant steroid hormones that play essential roles in growth and development. Mutations in BR-signaling pathways cause defective in growth and development like dwarfism, male sterility, abnormal vascular development and photomorphogenesis. Transition from vegetative to reproductive growth is a critical phase change in the development of a flowering plant. In a screen of activation-tagged Arabidopsis, we identified a mutant named abz126 that displayed longer hypocotyls when grown in the dark on MS media containing brassinazole (Brz), an inhibitor of BRs biosynthesis. We have cloned the mutant locus using adapter ligation PCR walking and identified that a single T-DNA had been integrated into the ninth exon of the GIGANTEA (GI) gene, involved in controling flowering time. This insertion resulted in loss-of-function of the GI gene and caused the following phenotypes: long petioles, tall plant height, many rosette leaves and late flowering. RT-PCR assays on abz126 mutant showed that the T-DNA insertion in GIGANTEA led to the loss of mRNA expression of the GI gene. In the hormone dose response assay, abz126 mutant showed: 1) an insensitivity to paclobutrazole (PAC), 2) an altered response with 6-benzylaminopurine (BAP) and 3) insensitive to Brassinolide (BL). Based on these results, we propose that the late flowering and tall phenotypes displayed by the abz126 mutant are caused by a loss-of-function of the GI gene associated with brassinosteroid hormone signaling.

• Microbiology and Biotechnology Letters
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• v.6 no.3
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• pp.129-133
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• 1978

A plating technique was devised to screen for high producing cellulase mutants of Trichoderma viride. The method employs: 1) The use of deoxycholate to limit colony size and 2) saponin to enhance cellulase detection in combiantion with rice straw pulp and pure cellulose on agar plate. The method will be used to isolate constitutive cellulase mutants of Trichoderma viride and should prove useful for isolating high producing mutants from a range of organisms.

• Molecules and Cells
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• v.44 no.12
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• pp.900-910
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• 2021

Sour is one of the fundamental taste modalities that enable taste perception in animals. Chemoreceptors embedded in taste organs are pivotal to discriminate between different chemicals to ensure survival. Animals generally prefer slightly acidic food and avoid highly acidic alternatives. We recently proposed that all acids are aversive at high concentrations, a response that is mediated by low pH as well as specific anions in Drosophila melanogaster. Particularly, some carboxylic acids such as glycolic acid, citric acid, and lactic acid are highly attractive to Drosophila compared with acetic acid. The present study determined that attractive carboxylic acids were mediated by broadly expressed Ir25a and Ir76b, as demonstrated by a candidate mutant library screen. The mutant deficits were completely recovered via wild-type cDNA expression in sweet-sensing gustatory receptor neurons. Furthermore, sweet gustatory receptors such as Gr5a, Gr61a, and Gr64a-f modulate attractive responses. These genetic defects were confirmed using binary food choice assays as well as electrophysiology in the labellum. Taken together, our findings demonstrate that at least two different kinds of receptors are required to discriminate attractive carboxylic acids from other acids.