• Molecules and Cells
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• 제38권3호
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• pp.259-266
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• 2015

The regulation of flowering time has crucial implications for plant fitness. MicroRNA156 (miR156) represses the floral transition in Arabidopsis thaliana, but the mechanisms regulating its transcription remain unclear. Here, we show that two AGAMOUS-like proteins, AGL15 and AGL18, act as positive regulators of the expression of MIR156. Small RNA northern blot analysis revealed a significant decrease in the levels of mature miR156 in agl15 agl18 double mutants, but not in the single mutants, suggesting that AGL15 and AGL18 co-regulate miR156 expression. Histochemical analysis further indicated that the double mutants showed a reduction in MIR156 promoter strength. The double mutants also showed reduced abundance of pri-miR156a and pri-miR156c, two of the primary transcripts from MIR156 genes. Electrophoretic mobility shift assays demonstrated that AGL15 directly associated with the CArG motifs in the MIR156a/c promoters. AGL18 did not show binding affinity to the CArG motifs, but pull-down and yeast two-hybrid assays showed that AGL18 forms a heterodimer with AGL15. GFP reporter assays and bimolecular fluorescence complementation (BiFC) showed that AGL15 and AGL18 co-localize in the nucleus and confirmed their in vivo interaction. Overexpression of miR156 did not affect the levels of AGL15 and AGL18 transcripts. Taking these data together, we present a model for the transcriptional regulation of MIR156. In this model, AGL15 and AGL18 may form a complex along with other proteins, and bind to the CArG motifs of the promoters of MIR156 to activate the MIR156 expression.

• 한국식물학회:학술대회논문집
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• 한국식물학회 2002년도 춘계학술발표대회:발표눈문요지록
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• pp.62-72
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• 2002

This study has investigated the biosynthesis and function of the heavy metal binding peptides, the phytochelatins, in plants. PCs are synthesised enzymatically from glutathione by the enzyme PC synthase in the presence of heavy metal ions. Using Arabidopsis thaliana as a model organism cadmium-sensitive, phytochelatin-deficient mutants have been isolated and characterised in previous studies. The cadl mutants have wildtype levels of glutathione, are PC deficient and lack PC synthase activity. Thus, the CADl gene has been proposed to encode PC synthase. The CADl gene was isolated by a positional cloning strategy The gene was mapped and a candidate identified. Each of four cadl mutants had a single base pair change in the candidate gene and the cadmium-sensitive, cadl phenotype was complemented by the candidate gene. This demonstrated the CADl gene had been cloned. A homologous gene in the fission yeast, Schizosaccharomyces pombe was identified through database searches. A targeted-deletion mutation of this gene was constructed and the mutant, like cadl mutants of Arabidopsis, was cadmium-sensitive and PC-deficient. A comparison of the redicted amino acid sequences reveals a highly conserved N-terminal region Presumed to be the catalytic domain and a variable C-terminal region containing multiple Cys residues proposed to be involved in activation of the enzyme by metal ions. Similar genes were also identified in animal species. The Arabidopsis CADl/AtPCSl and S. pombe SpbPCS genes were expressed in E. coli and were shown to be sufficient for glutathione-dependent, heavy metal activate PC synthesis in vitro, thus demonstrating these genes encode PC synthase enzymes. Using RT-PCR, AtPCSl expression appeared to be independent of Cd exposure. However, at higher levels of Cd exposure a AtPCSl-CUS reporter gene construct appeared to be more highly expressed. Using the reporter gene construct, AtPCSl was expressed most tissues. Expression appeared to be greater in younger tissues and same higher levels of expression was observed in some regions, including carpels and the base of siliques. AtPCS2 was a functional gene encoding an active PC synthase. However, its Pattern of expression and the phenotype of a mutant (or antisense line) have not been determined. Assuming the gene is functional then it has clearly been maintained through evolution and must provide some selective advantage. This implies that, at least in some cells or tissue, it is likely to be the dominant PC synthase expressed. This remains to be determined

• 한국미생물생명공학회:학술대회논문집
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• 한국미생물생명공학회 2003년도 2003 Annual Meeting, BioExhibition and International Symposium
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• pp.121-122
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• 2003

• Journal of Microbiology and Biotechnology
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• 제8권4호
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• pp.422-425
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• 1998

Chitin synthase null-mutants propagate in yeast form in RPMI medium with suppression of hyphal growth. This hyphal suppression is also observed in the wild type culture grown in RPMI medium supplemented with deer antler extract. To identify the possible target of deer antler extract, the enzymatic activities of chitin synthases were examined. The enzymatic activities of three chitin synthases, CAChsl, CAChs2, and CAChs3, were found to be differentially inhibited by deer antler extract. Of them, CAChsl, was the most sensitive to the extract. These results indicate that deer antler extract causes hyphal suppression, which resembles the effects of chitin synthase deletion, probably through direct inhibition of chitin synthases.

• 한국생물공학회:학술대회논문집
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• 한국생물공학회 2005년도 생물공학의 동향(XVII)
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• pp.465-467
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• 2005

UIW-10 mutant obtained by UV treatment using sulfur-oxidizing bacteria, Thiobacillus sp. IW was studied. The colony size of UIW-10 was found 2 $^{\sim}$ 3 times bigger in diameter than the parent colony on TAM medium. UIW-10 mutant growth was two times higher than parent strain at 6 h culture in liquid medium containing sulfides such as sulfur and sodium thiosulfate. Initial pH and temperature for the optimum growth of UIW-10 were 6.0 and $35-40^{\circ}C$, respectively. It was found that addition of 0.5% yeast extract and 0.5 to 2.0% tryptone as nitrogen sources and the constant agitation at 150 to 200 rpm had a positive effect and the growth of UIW-10 was increased.

• 한국미생물학회:학술대회논문집
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• 한국미생물학회 2002년도 추계학술대회
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• pp.209-214
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• 2002

• 한국식품영양학회지
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• 제13권2호
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• pp.158-163
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• 2000

Killer yeast, Hansenular capsulata S-13 were treated with heat, ethylmethane sulfonate and N-methyl-n'-nitro-n-nitrosoguanidine and a mutant(S13-E1), showing 2-fold higher killer toxin activity than that of parent strain to killer sensitive strain, Saccharomyces cerevisiae ATCC 38026 was obtained. Hansenular capsulata S13-E1 showed strong killer toxin activity to Saccharmyces mellis and Saccharomyces sal년 and four strains of gas-producing yeasts from traditional Doenjang and Kochujang. The culture condition for killer toxin production by Hansenular capsulata S13-E1 was optimized to be 1.0% potato extract, each 0.5% of peptone and glucose, and 0.025% MgSO4 with initial pH 4.5 at 3$0^{\circ}C$ and 36 hr of batch cultivation.

• 한국미생물·생명공학회지
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• 제14권4호
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• pp.299-304
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• 1986

동질의 유전적 배경을 가지는 1, 2, 3, 4 배체의 효모에 있어서 세포 체적, 세포 표면적, 균체농도, 건조 균체량, 자외선 저항성, 호흡결손 출현빈도. 발효력, 핵산 함량을 조사하였다. 자연 돌연변이에 의한 호흡결손 변이의 출현빈도는 2, 3, 4 배체보다 1배체에서 현저히 높게 나타났다. 세포 체적, 세포 포면적, 균체농도, 건조 균체량, 자외선 저항성, 발효력, DNA함량 등은 고차배수성에 따라 현저히 높아지는 경향을 나타냈다.

• 방사선산업학회지
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• 제6권2호
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• pp.181-188
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• 2012

A mushroom mutant with increased cellulolytic activity was developed through radiation mutagenesis. The homogenized hypha suspension of Pleurotus florida was exposed to gamma radiation ($^{60}Co$, AECL) at the dose of $LD_{99}$ (0.51 kGy, $D_{10}$; 0.26 kGy). Among 16 mutants, Pf CM4 showed 17.24% more cellulolytic activity than the wild type (p<0.05). It was observed that Pf CM4 can utilize all kinds of carbon sources tested for their mycelia growth. Starch, xylan, and glucose favourably supported the radial mycelia extension. Yeast extract and $NH_4NO_3$ have been recorded as the best organic and inorganic nitrogen sources, respectively. Pf CM4 was found to grow significantly faster, even at high temperature ($30^{\circ}C$), than wild type (p<0.05), and the optimal pH was 5.5~6.5. This study reveals that the mutant Pf CM4 could be employed for the effective recycling of cellulosic wastes, in addition to mushroom farming.

• Journal of Plant Biotechnology
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• 제5권3호
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• pp.143-148
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• 2003

Bax, a mammalian pro-apoptotic member of the Bcl-2 family induces cell death when expressed in yeast. To investigate whether Bax expression can induce cell death in plant, we produced transgenic Arabidopsis plants that contained murine Bax cDNA under control of a glucocorticoid-inducible promoter. Transgenic plants treated with dexamethasone, a strong synthetic glucocorticoid, induced Bax accumulation and cell death, suggesting that some elements of cell death mechanism by Bax may be conserved among various organisms. Therefore, we developed novel yeast genetic system, and cloned several Plant Bax Inhibitors (PBIs). Here, we report the function of two PBIs in detail. PBI1 is ascorbate peroxidase (sAPX). Fluorescence method of dihydrorhodamine123 oxidation revealed that expression of Bax in yeast cells generated reactive oxygen species (ROS), and which was greatly reduced by co-expression with sAPX. These results suggest that sAPX inhibits the generation of ROS by Bax, which in turn suppresses Baxinduced cell death in yeast. PBI2 encodes nucleoside diphosphate kinase (NDPK). ROS stress strongly induces the expression of the NDPK2 gene in Arabidopsis thaliana (AtNDPK2). Transgenic plants overexpressing AtNDPK2 have lower levels of ROS than wildtype plants. Mutants lacking AtNDPK2 had higher levels of ROS than wildtype. $H_2O_2$ treatment induced the phosphorylation of two endogenous proteins whose molecular weights suggested they are AtMPK3 and AtMPK6. In the absence of $H_2O_2$ treatment, phosphorylation of these proteins was slightly elevated in plants overexpressing AtNDPK2 but markedly decreased in the AtNDPK2 deletion mutant. Yeast two-hybrid and in vitro protein pull-down assays revealed that AtNDPK2 specifically interacts with AtMPK3 and AtMPK6. Furthermore, AtNDPK2 also enhances the MSP phosphorylation activity of AtMPK3 in vitro. Finally, constitutive overexpression of AtNDPK2 in Arabidopsis plants conferred an enhanced tolerance to multiple environmental stresses that elicit ROS accumulation in situ. Thus, AtNDPK2 appears to playa novel regulatory role in $H_2O_2$-mediated MAPK signaling in plants.