Tae-Shick Yu

Modulation of Sp1-dependent transcription by a cis-acting E2F element in dhfr promoter.

The dihydrofolate reductase (dhfr) promoter contains cis-acting elements for Sp1 and E2F. Here we examined the cooperative regulation of dhfr gene transcription by Sp1 and E2F in human osteosarcoma cells, U2OS. Trichostatin A, an inhibitor of histone deacetylases, markedly stimulated dhfr promoter activity, a response that was enhanced by the deletion of an E2F element. In contrast, deletion of the dhfr Sp1 binding sites completely abolished promoter stimulation by trichostatin A. Cotransfection assays showed that activation of dhfr transcription by expression of E2F1/DP1 requires the reiterated Sp1 elements, whereas activation by Sp1 was enhanced by the deletion of the E2F element. Expression of HDAC1 with Sp1 suppressed promoter activity and suppression was not alleviated by coexpression of E2F1/DP1. These results suggest that HDAC1 acts through Sp1 to repress dhfr promoter activity, and that the E2F element modulates the activity of Sp1 at the dhfr promoter through a cis-acting mechanism.

Characteristics of Ju-Back and Effect of Ju-Back Fertilizer on Growth of Crop Plants

This experiment was conducted to develop fertilizer which promotes plant growth as well as suppressing pathogenic fungi. The fertilizer was made from the mixture of Ju-Back (Korean rice wine cake) and indigenous rhizosphere-bacterium. The main ingredients of Ju-Back were investigated as 6.04% total nitrogen, 42.59% total carbohydrate, 1.01% available phosphate, 73.42% organic matter, 7.72% potassium oxide, 1.35% calcium oxide, 0.53% magnesium oxide. The enzyme activities of Ju-Back were estimated to be 980 units/g for , 300 units/g for glucoamylase, and 1800 units/g for acid pretense. Indigenous rhizosphere bacteria which produced antifungal agent were isolated from soil, and was selected KMU-13 strain which can antagonize against various plant pathogenic fungi (Botrytis cinerea KACC 40573, Sclerotinia sclerotiorum KACC 41065, Fusairum oxysporum KACC 40052, Pythium aphanidermatum KACC 40156, Phytophthora capsici KACC 40476 and Glomerella cingulata KACC 40299). KMU-13 strain was identified as Bacillus subtilis KMU-13 by biochemical and 16s rDNA analysis. The organic fertilizer was made as prototype which was composed 20% Ju-Back, 70% carrier, 9.7% microorganism cultivated solution, 0.3% trace-element. We also investigated an application of fertilizer using Ju-Back for cultivating lettuce (Lactuca sativar) which were grown in three soil conditions that had chemical fertilizer, barnyard manure, lime power, urea, potassium chloride and superphosphate as a control, the whole quantity (80 kg/10a) of posted fertilizer with the control and the half quantity (40 kg/10a) with the control. The growth characteristics were examined and analysed with several weeks interval from 3 weeks to 8 weeks on head length (cm), head width (cm/head), number of leaf and fresh weight (g/plant). The results are summarized as follows. The head width and fresh weight of lettuce were the highest at posted fertilizer 1 (whole quantity) was applied chemical, organic matter (Ju-Back) and carrier. The head length was the highest at posted fertilizer 2 (whole quantity) was applied Ju-Back only.

Purification of Cytosine Deaminase from Serratia marcescens

Cytosine deaminase was purified about 900-fold from the cell-free extract of Serratia marcescens. The purification procedure included heat treatment, ammonium sulfate fractionation, ethyl alcohol fractionation, DEAE-cellulose and hydroxylapatite column chromatography, and Sephadex G–200 gel filtration.The enzyme was homogeneous by the criteria of ultracentrifugation and acrylamide gel electrophoresis. The molecular weight was determined to be approximately 580,000 and the molecule was composed of equimolecular weight of 8 subunits.The enzyme catalyzed the stoichiometric conversion of cytosine into uracil and ammonia.

Purification and properties of cytosine deaminase from Aspergillus fumigatus

Abstract Cytosine deaminase (EC 3.5.4.1) from Aspergillus fumigatus IFO 5840, which is the first cytosine deaminase to be found in a mould, was purified 150-fold with an overall yield of 0.75%, to homogeneity judging from disc and SDS-polyacrylamide gel electrophoresis. The enzyme was a monomer of 32 kDa. Besides cytosine, the enzyme stoichiometrically deaminated 5-methylcytosine and 5-fluorocytosine: the activity toward them was 100:28:43, and the apparent K m values for them were 2, 36, and 6.5 mM, respectively. The enzyme had a pH optimum at around pH 7 and temperature optimum at 35°C. The enzyme activity was inhibited by heavy metal ions such as Fe 2+ , Cu 2+ , Hg 2+ , and Pb 2+ at 0.1 mM, and by p -chloromercuribenzoate, o -phenanthroline, ATP, and UTP at 1 mM.

Antifungal Activity of Extract from Xmthitim strumarium L. Against Plant Pathogenous fungi.

Antifungal activity of ether and ethylacetate extract from Xanthium strumarium L. were tested against 11 plant pathogens by agar diffusion method. Antifungal activity of the ether and ethylacetate extract showed strong antifungal activity against plant pathogenous fungi, i.e. Phytophthora capsici, Sclerotinia sclerotiorum and Aspergillus niger. The IC50 of the ether extract against Sclerotinia sclerotiorum was determined 335 ㎍/ml. Antifungal activity of the ether extract from Xanthium strumarium L. showed Rf value=0.87 on TLC plate.