Byung Yeoup Chung

Alterations in the Photosynthetic Pigments and Antioxidant Machineries of Red Pepper (Capsicum annuum L.) Seedlings from Gamma-Irradiated Seeds

To characterize the stimulatory effects of low-dose gamma radiation on early plant growth, we investigated alterations in the photosynthesis and antioxidant capacity of red pepper (Capsicum annuum L.) seedlings produced from gamma-irradiated seeds. For two cultivars (Yeomyung and Joheung), three irradiation groups (2, 4, and 8 Gy, but not 16 Gy) showed enhanced development, although Fv/Fm, the maximum photochemical efficiency of Photosystem II (PSII), did not differ significantly among any of the four groups. In contrast, values for 1/Fo — 1/Fm, i.e., a measure of functional PSII content, decreased in the irradiated groups of ‘Yeomyung’ but increased in those of ‘Joheung’. Pigment analyses and enzyme activity assays revealed that irradiation altered the compositions of photosynthetic pigments (chlorophylls and carotenoids) as well as the activities of antioxidant enzymes (superoxide dismutase and glutathione reductase). However, these shifts were not directly related to the increase in early growth, although they were cultivar-and developmental stage-dependent In addition, the effects of irradiation on the enzymatic activities measured here were at opposition between the two cultivars.

Ultrastructural changes of cell organelles inArabidopsis stems after gamma irradation

We examined ultrastructural changes of the cell organelles ofArabidopsis stems in response to gamma irradiation. Seedlings treated with 0 to 5 Gy developed normally, while height growth in plants exposed to 50 Gy was significantly inhibited. Based on TEM observations, the chloroplasts were extremely sensitive to such irradiation. In particular, the thylakoids were heavily swollen, some portions of the mitochondria and endoplasmic reticulum were structurally altered, and the plasmalemma had pulled away from the cell wall in places. However, no ultrastructural changes in cell organelles occurred at doses of 0 to 5 Gy.

Heavy Metals in Brown Rice (Oryza sativa L.) and Soil After Long-Term Irrigation of Wastewater Discharged from Domestic Sewage Treatment Plants

A pot experiment was conducted in a plastic film house to evaluate the translocation and uptake of heavy metals (Pb, Cd, Cu, and Zn) into brown rice (Oryza sativa L.) and the heavy metals residues in soils which had previously been irrigated with domestic wastewater for a long time (3 years). The range of Pb, Cd, Cu, and Zn was 5.10 ± 0.01, 0.105 ± 0.017, 5.76 ± 0.42, and 23.56 ± 1.40 mg kg−1, respectively in the domestic wastewater-irrigated soil, and 0.370 ± 0.006, 0.011 ± 0.001, 0.340 ± 0.04, and 2.05 ± 0.18 mg kg−1, respectively, in the domestic wastewater-irrigated brown rice. The results indicated that application of domestic wastewater to arable land slightly increased the levels of Pb, Cd, Cu, and Zn in soil and brown rice (P < 0.01). The concentrations of heavy metals in brown rice were lower than the recommended tolerable levels proposed by the Joint FAO/WHO Expert Committee on Food Additives. However, the continuous monitoring and pollution control of hazardous materials from domestic wastewater are needed in order to prevent excessive build-up of heavy metals in the food chain.

Radiolytic transformation of rotenone with potential anti-adipogenic activity.

Radiolytic transformation of the isoflavonoid rotenone (1) with γ-irradiation afforded two new degraded products, rotenoisins A (2) and (3). The structures of the two new rotenone derivatives were elucidated on the basis of spectroscopic methods. The new products 2 and 3 exhibited significantly enhanced inhibitory activities against pancreatic lipase and adipocyte differentiation in 3T3-L1 cells when compared to parent rotenone.

cDNA cloning and sequence analysis of the rice Cinnamate-4-Hydroxylase gene, a cytochrome P450-dependent monooxygenase involved in the general phenylpropanoid pathway

Plant cytochrome P450 monooxygenases (P450s) mediate a wide range of oxidative reactions involved in the biosynthesis of phenylpropanoids, terpenes, lipids, and alkaloids. We isolated a cDNA clone for cinnamate-4-hydroxylase (C4H) from a Japonica type rice(Oryza sativa L. cv. llpumbyeo). This C4H has a deduced amino acid sequence that is 85% identical tothat ofSorghum bicolor. Our phylogenetic analysis also showed that theOsC4HL gene is closely related toC4H fromS. bicolor. A putative genomic DNA sequence corresponding toOsC4HL contained cis-elements (boxes P, A, L, and TCA motifs), AT-rich elements, and wound-response elements that control gene expression in its promoter region.OsC4HL expression was detected in all the tissue types, with the highest level being measured in the roots. It was also apparently up-regulated by wounding stress. These data suggest that theOsC4HL gene isC4H member in theCYP73 subfamily.

Localization of hydrogen peroxide in pumpkin (Cucurbita ficifolia bouché) seedlings exposed to high-dose gamma ray

Hydrogen peroxide (H2O2) was detected cytochemically, via transmission electron microscopy (TEM), in pumpkin tissues exposed to high-dose gamma ray. Its reaction with cerium chloride produced electron-dense precipitates of cerium perhydroxides. Their patterns of deposition in the tissues of both control plants and those irradiated with gamma ray (PIG) were typically found in the plasma membranes and cell walls. However, gamma irradiation remarkably increased the intensities of cerium perhydroxide deposits (CPDs) in the plasma membranes and cell walls for all tissue types, but especially the leaves. The only exception was for vessels in the cotyledons. After gamma irradiation, the (H2O2) content in all tissues was higher than in the control samples, except for the cotyledons of PIG, where the (H2O2) content was lower than for all others. The increased appearance of CPDs may have been due to the enhancement of (H2O2) accumulation by gamma radiation. This accumulation also varied according to the cell or tissue type examined.

Decomposition reaction of the veterinary antibiotic ciprofloxacin using electron ionizing energy.

The application of electron ionizing energy for degrading veterinary antibiotic ciprofloxacin (CFX) in aqueous solution was elucidated. The degradation efficiency of CFX after irradiation with electron ionizing energy was 38% at 1 kGy, 80% at 5kGy, and 97% at 10 kGy. Total organic carbon of CFX in aqueous solution after irradiation with electron ionizing energy decreased 2% at 1 kGy, 18% at 5 kGy, and 53% at 10 kGy. The CFX degradation products after irradiation with electron ionizing energy were CFX1 ([M+H] m/z 330), CFX2 ([M+H] m/z 314), and CFX3 ([M+H] m/z 263). CFX1 had an F atom substituted with OH and CFX2 was expected to originate from CFX via loss of F or H2O. CFX3 was expected to originate from CFX via loss of the piperazynilic ring. Among the several radicals, hydrate electron (eaq(-)) is expected to play an important role in degradation of veterinary antibiotic during irradiation with electron ionizing energy. The toxicity of the degraded products formed during irradiation with electron ionizing energy was evaluated using microbes such as Escherichia coli, Pseudomonas putida, and Bacillus subtilis, and the results revealed that the toxicity decreased with irradiation. These results demonstrate that irradiation technology using electron ionizing energy is an effective was to remove veterinary antibiotics from an aquatic ecosystem.

A comparison of the efficiency of electron beam irradiation on enzymatic hydrolysis between 4 doses of 25 kGy and a single dose of 100 kGy for bioethanol production

A significant challenge in biofuel production is the inefficient hydrolysis of lignocellulosic materials into simple sugar for conversion into fuel ethanol. This low efficiency results in part from lignin restricting the access of degradative enzymes to cellulose. Wheat straws exposed to electron beams ranging from 0 to 100 kGy were examined to determine effect of divided irradiation (25 kGy in 4 tandem doses) vs. single irradiation (100 kGy). Yields of reducing sugars such as glucose and xylose after divided irradiation (51.1%) showed only a small increase relative to the control (40.9%), whereas in single irradiation, the yields of reducing sugars substantially increased to 74.9%. Results of X-ray diffraction showed crystallinity of cellulose slightly decreased from 43.0 to 38.8% after divided irradiation. Significant decrease to 34.1% was observed after single irradiation. Removal of hemicelluloses and modification of lignin polymer were also observed. These results indicate electron beam irradiation has destructive influence on both physical and chemical properties of wheat straw, thereby increasing accessibility of the cellulose surface to enzymatic hydrolysis and theoretically enable more efficient cellulose hydrolysis. Moreover, divided irradiation did not show a significant influence on enzymatic hydrolysis; hence, the single irradiation process is more effective than divided irradiation for increasing hydrolysis efficiency.

Molecular mechanism of apoptosis induction in skin cancer cells by the centipedegrass extract.

BackgroundCentipedegrass extract (CGE) is mainly composed of maysin and its derivatives, which are recognized internationally as natural compounds. Compared to other flavonoids, maysin has a unique structure in that mannose is bound to the flavonoid backbone. CGE exhibits some biological properties in that it can function as an anti-oxidant, anti-inflammatory, anti-adipogenic, and insecticidal. Whether CGE has other biological functions, such as anti-cancer activity, is unknown.MethodsB16F1 (mouse) and SKMEL-5 (human) cells were treated with CGE, and their subsequent survival was determined using MTT assay. We performed a cell cycle analysis using propidium iodide (PI), and detected apoptosis using double staining with annexin V-FITC/PI. In addition, we examined mitochondrial membrane potentials using flow cytometry, as well as signaling mechanisms with an immunoblotting analysis.ResultsCGE inhibited skin cancer cell growth by arresting the cell cycle in the G2/M phase, and increased both early and late apoptotic cell populations without affecting normal cells. Furthermore, we observed mitochondrial transmembrane depolarization, increased cytochrome-c release, caspase-3 and caspase-7 activation, and increased poly ADP-ribose polymerase degradation. CGE also downregulated activation of p-AKT, p-glycogen synthase kinase-3β (GSK-3β), and p-BAD in a time-dependent manner. LY294002 inhibition of phosphoinositide 3-kinase (PI3K) significantly sensitized skin cancer cells, which led to an increase in CGE-induced apoptosis.ConclusionsCGE controlled skin cancer cell growth by inhibiting the PI3K/AKT/GSK-3β signaling pathway and activating the effector caspases. This study is the first to demonstrate anti-cancer properties for CGE, and that CGE may be an effective therapeutic agent for treating skin cancer.

Degradation of cyanidin-3-rutinoside and formation of protocatechuic acid methyl ester in methanol solution by gamma irradiation

Anthocyanins are naturally occurring phenolic compounds having broad biological activities including anti-mutagenesis and anti-carcinogenesis. We studied the effects and the degradation mechanisms of the most common type of anthocyanins, cyanidin-3-rutinoside (cya-3-rut), by using gamma ray. Cya-3-rut in methanol (1mg/ml) was exposed to gamma-rays from 1 to 10kGy. We found that the reddish colour of cya-3-rut in methanol disappeared gradually in a dose-dependent manner and effectively disappeared (>97%) at 10kGy of gamma ray. Concomitantly, a new phenolic compound was generated and identified as a protocatechuic acid methyl ester by liquid chromatography, (1)H, and (13)C NMR. The formation of protocatechuic acid methyl ester increased with increasing irradiation and the amount of protocatechuic acid methyl ester formed by decomposition of cya-3-rut (20μg) at 10kGy of gamma ray was 1.95μg. In addition, the radical-scavenging activities were not affected by gamma irradiation.