Search

Plants regulate a number of primary metabolites, including carbohydrates, organic acids, and amino acids, in response to UV-B radiation. Therefore, it is essential to understand the time-dependent response of rice plants to UV-B stress. This study focused on the response of plants to UV-B at different leaf developmental phases (emerging, growing, and maturing) in an attempt to fully comprehend the metabolic shift. We analyzed the expression levels of genes related to starch/sucrose metabolism in the leaf blades of rice seedlings (Oryza sativa L. “Saechuchenog”) exposed to UV-B irradiation for short (1 day) and long terms (5 days) using quantitative real-time polymerase chain reaction. We also examined the diurnal variations in the contents of primary metabolites using an established GCTOF-MS (gas chromatography time of flight-mass spectrometry) method. The results showed that the levels of primary metabolites were largely dependent upon the diurnal rhythm and leaf developmental phase. The young leaves (sink) produced and accumulated starch rather than sucrose. The short-term (4 h, 1 day) UV-B exposure inhibited sucrose synthesis, which could be the first target of UV-B radiation. Following short- and long-term (5 days) exposure to UV-B radiation, the dynamic response of primary metabolites was evaluated. It was found that the content of carbohydrates decreased throughout the period of exposure to UV-B stress, especially in terms of sucrose concentration. However, the content of the majority of amino acids increased after an early decrease. Our data revealed that the metabolic response, as well as the gene expression, differed with the period (intensity) of exposure to UV-B radiation and with the phase of leaf development. These findings provide new insights for a better understanding of the metabolic response of a variety of plant species exposed to a wide range of UV-B radiation.

An estimation of the requirement of minerals based on growth stage and cropping pattern is very important for greenhouse zucchini. This study was performed at farmer’s field which was applied with a fertigation system and a semi-forcing cultivation from Feb. to July in 2014, and nitrogen levels were set up with x0.5, x0.75, x1.0 and x1.5 of the NO₃-N-based soil-testing recommendation for zucchini cultivation. Top dressing of nitrogen (basal : top = 4 : 6) and potassium (basal : top = 3 : 7) was applied with an interval of every two weeks from two and six weeks after transplanting, respectively, and phosphorus was totally supplied with basal dressing. The nitrogen uptake was the order of x1.0, x0.75, x1.5 and x0.5, phosphorus, x1.0, x0.75, x0.5 and x1.5, and potassium, x0.75, x1.0, x1.5 and x0.5. From these results, it was suggested that highest mineral uptake could be reached between x0.75 and x1.0 of the NO₃-N-based soil-testing recommendation. In conclusion, nutrient management based on the growth stage was proven to be better method for favorable growth and yield of zucchini.

This study was conducted to evaluate the effects of reduced nitrogen (N) and potassium (K) fertigation as additional fertilizer on tomato yield and nutrient contents in excessively nutrients-accumulated soil. Shoot and root dry weights (DW), dry matter rate for shoot, root and fruit and number of fruit in both AF50 and AF100 (50 and 100% levels of additional fertilizer) treatments were increased in comparison with those in AF0 (0% level of additional fertilizer) treatment. In case of nutrient uptake by tomato, nitrogen, phosphorous (P) and potassium contents in all tomato parts (leaf, stem, root and fruit) in AF50 and AF100 treatment were lower than those in AF0 treatment. On the contrary, soluble sugar and starch contents in all tomato parts in AF50 and AF100 were higher than those in AF0 treatment. There were differences between AF0 and AF50 or AF100 in tomato growth, yield, nutrient level and contents of soluble sugar and starch. In contrast, the level and initiation point of fertigation did not significantly affect the parameters. Based on our results, the application of properly reduced level of additional fertilizer is possible to maintain the productivity of tomato and alleviate the nutrient accumulation in plastic film house soils.

New tandem mass spectrometric method coupled with liquid chromatography (LC-MS/MS) has been developed to determine the total concentration of camptothecin derivatives (irinotecan and SN-38) regardless of inter-conversion phenomenon between carboxylate and lactone forms. At first, all sample solutions were acidified for 1h in order to completely convert CPT derivatives into their lactone forms and then CPT derivatives were extracted with organic solution containing diethyl ether and ethyl acetate (2:1, v/v) just after alkalization in the range pH 8.0-8.5 in acid-treated solutions. Analytes were separated on a reverse phase C18 column (150×2.1mm) and eluted isocratically with a mobile phase which consisted of acetonitrile-methanol-buffer (0.1% formic acid, 5mM ammonium formate) (3:4:3, v/v). CPT derivatives were monitored by tandem mass spectrometry in electrospay-positive ionization and multiple reaction mode programmed to the following transitions (m/z): '587.6→167.2' of CPT-11, '393.6→349.3' of SN-38 and '349.4→ 305.2' of CPT. The method was validated to have the proper linearity (r(2)>0.99) over the range of 5-1000ng/ml of CPT-11 and 1-250ng/ml of SN-38 with good accuracy (89.8-114.3%) and precision (less than 10%). In all stability tests, concentration of CPT-11 and SN-38 had been left in the acceptable range of 88.8-110.7% when sample solutions were acidified before determination of CPT derivatives. Newly developed LC-MS/MS method was suitable for the determination of CPT derivatives of both rabbit plasma and tumor tissues in the pharmacokinetic study.

Expected climatic changes likely elicit serious challenges for crop production. Therefore, it is indispensable to investigate the response of crop growth parameters and yield under temperature variability environments. The current experiment on chilli pepper growth was conducted in a field, rain-shelter plastic house, and plastic greenhouse, with accumulated temperatures of 2832 &deg, C, 2967 &deg, C, and 3105 &deg, C in 2017, and 2944 &deg, C, 3091 &deg, C, and 3168 &deg, C in 2018 growing seasons. Based on soil analysis, 132.7 kg ha&minus, 1 (1&times, of livestock manure compost as an optimum and 265.4 kg ha&minus, 1 (2&times, ) as a double amount of organic matter were applied to each simulated temperature condition. The results showed that organic manure application favorably affects the growth attributes and nutrient uptake of chilli pepper with the highest values found in the plastic greenhouse, followed by the rain-shelter house, over the open field cultivation condition. The highest growth of chilli pepper was at the 2&times, rate of organic manure application, whereas the highest yield was found at the 1&times, rate of organic manure application. The application of organic manure at the 1&times, rate in the greenhouse increased root, shoot, and fruit dry weights of chilli pepper by 21.4%, 52.4%, and 79.7%, respectively, compared to the control values. These results indicate that the rational use of organic amendments might be the best solution for chilli pepper production under variable climate conditions.

LRRK2 (leucine-rich repeat kinase 2) has been identified as a gene corresponding to PARK8, an autosomal-dominant gene for familial Parkinson’s disease (PD). LRRK2 pathogenicspecific mutants induce neurotoxicity and shorten neurites. To elucidate the mechanism underlying LRRK2 expression, we constructed the LRRK2-promoter-luciferase reporter and used it for promoter analysis. We found that the glucocorticoid receptor (GR) transactivated LRRK2 in a ligand-dependent manner. Using quantitative RT-PCR and Western analysis, we further showed that treatment with dexamethasone, a synthetic GR ligand, induced LRRK2 expression at both the transcriptional and translational levels, in dopaminergic MN9D cells. Dexamethasone treatment also increased expression of α-synuclein, another PD causative gene, and enhanced transactivation of the α-synuclein promoter-luciferase reporter. In addition, dexamethasone treatment to MN9D cells weakly induced cytotoxicity based on an LDH assay. Because glucocorticoid hormones are secreted in response to stress, our data suggest that stress might be a related factor in the pathogenesis of PD. [BMB Reports 2013; 46(9): 454-459]

The constitutive androstane receptor (CAR) is a member of the nuclear receptor superfamily and plays an important role in the degradation of xenobiotics in the liver. Using yeast two-hybrid screening, we identified SF3a3, a 60-kDa subunit of the splicing factor 3a complex, as a specific CAR-interacting protein. We further confirmed their interaction by both co-immunoprecipitation and GST pull-down assay. Functional studies showed that overexpression of SF3a3 inhibited the reporter activity driven by a promoter containing CAR binding sequences by up to 50%, whereas reduced expression of SF3a3 activated the same reporter activity by approximately three-fold. The inhibitory function of SF3a3 is independent of the presence of TCPOBOP, a CAR ligand. These data suggest that SF3a3 functions as a co-repressor of CAR transcriptional activity, in addition to its canonical function.