• Korean Journal of Breeding Science
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• v.41 no.3
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• pp.252-260
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• 2009

Rice is the most important cereal crop not only in supplying the basic staple food for more than half of the world's population but also as a model plant for functional genomic studies of monocotyledons. Although rice transformation method using A. tumefaciens has already been widely used to generate transgenic plants, the transformation rate is still low in most Korean elite cultivars. We made several modifications of the standard protocol especially in the co-cultivation step to improve the efficiency of the rice transformation. The co-culture medium was modified by the addition of three antioxidant compounds (10.5 mg/L L-cysteine, 1 mM sodium thiosulfate, 1 mM dithiothreitol) and of Agrobacterium growth-inhibiting agent (5 mg/L silver nitrate). Co-cultivation temperature ($23.5^{\circ}C$ for 1 day, $26.5^{\circ}C$ for 6 days) and duration (7 days) were also changed. The plasmid of pMJC-GB-GUS carrying the GUS reporter gene and the bar gene as the selectable marker was used to evaluate the efficiency of the transformation. After co-cultivation, a high level of GUS gene expression was observed in calli treated with the modified method. It is likely that those newly added compounds helped to minimize the damage due to oxidative bursts during plant cell-Agrobacterium interaction and to prevent necrosis of rice cells. And the transformation rate under the modified method was also remarkably increased approximately 8-fold in Heungnambyeo and 2-fold in Ilmibyeo as compared to the corresponding standard method. Furthermore, we could produce the transgenic plants stably from Ilpumbyeo which is a high-quality rice but its transformation rate is extremely low. Transformation and the copy number of transgenes were confirmed by PCR, bar strip and Southern blot analysis. The improved method would attribute reducing the effort and the time required to produce a large number of transgenic rice plants.

• Animal Bioscience
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• v.34 no.12
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• pp.2023-2033
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• 2021

Objective: The present study was conducted to assess the effect of urease inhibitor (hydroquinone [HQ]) and nitrification inhibitor (dicyandiamide [DCD]) on nitrogen (N) use efficiency of pig slurry for perennial ryegrass regrowth yield and its environmental impacts. Methods: A micro-plot experiment was conducted using pig slurry-urea ¹⁵N treated with HQ and/or DCD and applied at a rate of 200 kg N/ha. The flows of N derived from the pig slurry urea to herbage regrowth and soils as well as soil N mineralization were estimated by tracing pig slurry-urea ¹⁵N, and the N losses via ammonia (NH₃), nitrous oxide (N₂O) emission, and nitrate (NO₃^-) leaching were quantified for a 56 d regrowth of perennial ryegrass (Lolium perenne) sward. Results: Herbage dry matter at the final regrowth at 56 d was significantly higher in the HQ and/or DCD applied plots, with a 24.5% to 42.2% increase in ¹⁵N recovery by herbage compared with the control. Significant increases in soil ¹⁵N recovery were also observed in the plots applied with the inhibitors, accompanied by the increased N content converted to soil inorganic N (NH₄⁺+NO₃^-) (17.3% to 28.8% higher than that of the control). The estimated loss, which was not accounted for in the herbage-soil system, was lower in the plots applied with the inhibitors (25.6% on average) than that of control (38.0%). Positive effects of urease and/or nitrification inhibitors on reducing N losses to the environment were observed at the final regrowth (56 d), at which cumulative NH₃ emission was reduced by 26.8% (on average 3 inhibitor treatments), N₂O emission by 50.2% and NO₃^- leaching by 10.6% compared to those of the control. Conclusion: The proper application of urease and nitrification inhibitors would be an efficient strategy to improve the N use efficiency of pig slurry while mitigating hazardous environmental impacts.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2016.05a
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• pp.132-134
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• 2016

The Study mainly focused on bioremediation of 16 types PAHs and heavy metals in contaminated marine sediments at filed scale study using slow release biostimulant ball (BSB) was investigated. In our experiment, filed scale study ($1m{\times}1m$) was performed and the effect of BSB on PAHs and heavy metals were analysed. BSB size and distance were determined and optimum size and distance were 3cm and 5.5cm respectively. BSB containing nutrients of acetate, nitrate and sulphate which can enhance the activity of microorganism to increase degrading capacity of PAHs and enhance the heavy metals stabilization also to decrease bioavailability. PAHs containing 16 types of 2, 3, 4, 5 and 6 rings compound PAHs were found and to degrade upto 100% in 2, 3 rings, upto 90 to 94% in 4 and 5 rings and 6 ring compound was degrade up to 70%. For heavy metals stabilization percentage was increased using BSB sediment and exchangeable portion was decreased and residual portion was increased in all analysed heavy metals. BSB enhance the PAHs degradation and stabilization of heavy metals percentages. BSB is a promising method for remediation of PAHs and heavy metals in contaminated marine sediments.

• Journal of Microbiology and Biotechnology
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• v.21 no.2
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• pp.154-161
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• 2011

L. lactis sk071115 has been shown to grow more actively and generate lower levels of lactate in glucose-defined medium with nitrate than in medium with Mn(IV). By adding Mn(IV) to a L. lactis culture, lactate production was relatively reduced in combination with Mn(II) production, but cell mass production levels did not increase. Both cell-free extract and intact L. lactis cells reacted electrochemically with Mn(IV) but did not react with Mn(II) upon cyclic voltammetry using neutral red (NR) as an electron mediator. A modified graphite felt cathode with NR (NR-cathode) was employed to induce electrochemical reducing equivalence for bacterial metabolism. Cell-free L. lactis extract catalyzed the reduction of Mn(IV) to Mn(II) under both control and electrochemical reduction conditions; however, the levels of Mn(II) generated under electrochemical reduction conditions were approximately 4 times those generated under control conditions. The levels of Mn(II) generated by the catalysis of L. lactis immobilized in the NR-cathode (L-NR-cathode) under electrochemical reduction conditions were more than 4 times that generated under control conditions. Mn(II) production levels were increased by approximately 2.5 and 4.5 times by the addition of citrate to the reactant under control and electrochemical reduction conditions, respectively. The cumulative Mn(II) produced from manganese ore by catalysis of the L-NR-cathode for 30 days reached levels of approximately 3,800 and 16,000 mg/l under control and electrochemical reduction conditions, respectively. In conclusion, the electrochemical reduction reaction generated by the NR-cathode activated the biochemical reduction of Mn(IV) to Mn(II) by L. lactis.

• YAKHAK HOEJI
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• v.48 no.6
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• pp.317-322
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• 2004

The use of nonsteroidal anti-inflammatory drugs (NSAIDs) is limited by their ability to induce gastrointestinal injury. It has been shown that nitric oxide (NO), similar to pro staglandins (PGs), appears to play an important role in gastric mucosal defence. We hypothesized that NSAIDs contained NO group would be less acutely toxic to the gastric mucosa, but would not interfere with their ability to suppress inflammatory process in rats. We have compared the ulcerogenic and anti-inflammatory effect of CW-501029 (NO-NSAIDs), CW-501027 (NSAIDs) and indomethacin. Both did not change mean blood pressure and heart rates, indicating that they had no side effect on cardiovascular system. We found that CW-501029 increased nitrite/nitrate levels without changing of blood pressure and heart rates. We suggest that it may help gastric mucosal blood flow, the which helps reducing the discomfort in astrointestinal system. Carrageenan-induced PGE2 increase was reduced in a similar tendency when compared CW-501027 or CW-501027 with control in back exudate of rats, but CW-501029 less reduced PGE2 than CW-502027 or indomethacin in gastric tissues. CW-501027 or CW-501029 reduced platelet aggregation. From these results we suggest that CW-501029 may improve the side effect by reduction of short-term gastric injury and less inhibition of PGs synthesis.

• Journal of Ecology and Environment
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• v.30 no.3
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• pp.209-223
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• 2007

Twenty-four wetlands located in Higashi-Hiroshima City in West Japan were selected for this study in order to investigate both the relationship between aquatic plant composition and environmental conditions; and the relationship between changing land use patterns in the catchments and the concentration of different forms of nitrogen in the wetlands. The dominant and subdominant species which comprised the principal vegetation were determined based on a vegetation census conducted in each wetland during the growing season from June to August, 2006. The seasonal variations of water quality factors (pH, electrical conductivity, turbidity, dissolved oxygen, total dissolved solid, and temperature) and different forms of nitrogen such as nitrite, nitrate, ammonium, total nitrogen, dissolved organic nitrogen and dissolved inorganic nitrogen concentrations were analyzed as important indicators of water quality for the surface water of the wetlands. The surveyed wetlands were classified into three types (non-disturbed wetlands, moderately-disturbed wetlands and highly-disturbed wetlands), based on the degree of human disturbance to their catchment areas. An analysis of variance indicated that there was a significant difference among the wetland groups in the annual mean values of electrical conductivity, total dissolved solids, total nitrogen, nitrite, dissolved inorganic nitrogen and dissolved organic nitrogen. Classification of the wetlands into three groups has revealed a pattern of changes in the composition of plant species in the wetlands and a pattern of changes in nitrogen concentrations. A majority of the non-disturbed wetlands were characterized by Brasenia schrebi and Trapa bispinosa as dominant; with Potamogeton fryeri and Iris pesudacorus as sub-dominant species. For most of the moderately-disturbed wetlands, Brasenia schrebi were shown to be a dominant species; Elocheriss kuriguwai and Phragmites australis were observed as sub-dominant species. For a majority of the highly-disturbed wetlands, Typha latifolia and T. angustifolia were observed as dominant species, and Nymphea tetragona as the sub-dominant species in the study area. An analysis of land use and water quality factors indicated that forest area played a considerable role in reducing the concentration of nutrients, and can act as a sink for surface/subsurface nutrient inputs flowing into wetland water, anchor the soil, and lower erosion rates into wetlands.

• Journal of Crop Science and Biotechnology
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• v.10 no.2
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• pp.57-63
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• 2007

Due to the strong influence of nitrogen(N) on plant productivity, a vast amount of N fertilizers is used to maximize crop yield. Over-use of N fertilizers leads to severe pollution of the environment, especially the aquatic ecosystem, as well as reducing farmer's income. Growing of N-efficient cultivars is an important prerequisite for integrated nutrient management strategies in both low- and high-input agriculture. Taking maize as a sample crop, this paper reviews the response of plants to low N stress, the physiological processes which may control N-use efficiency in low-N input conditions, and the genetic and molecular biological aspects of N-use efficiency. Since the harvest index(HI) of modern cultivars is quite high, further improvement of these cultivars to adapt to low N soils should aim to increase their capacity to accumulate N at low N levels. To achieve this goal, establishment and maintenance of a large root system during the growth period may be essential. To reduce the cost of N and carbon for root growth, a strong response of lateral root growth to nitrate-rich patches may be desired. Furthermore, a large proportion of N accumulated in roots at early growth stages should be remobilized for grain growth in the late filling stage to increase N-utilization efficiency. Some QTLs and genes related to maize yield as well as root traits have been identified. However, their significance in improving maize NUE at low N inputs in the field need to be elucidated.

• Journal of Microbiology and Biotechnology
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• v.16 no.10
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• pp.1537-1543
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• 2006

A bacterial strain named HY-3 that produces a highly active extracellular protease was isolated from the digestive tract of a spider, Nephila clavata. The bacterium was a Gram-negative, oxidase-negative, catalase-positive, nonhalophilic, nitrate-reducing, facultative anaerobe. Transmission and scanning electron microscopies demonstrated that the isolate was non-spare-forming, straight, rod-shaped, and motile by peritrichous flagella. The G+C content of the DNA was 57.0 mol%. The isoprenoid quinone type was ubiquinone with 8 isoprene units (Q-8). The morphological and biochemical characteristics including the predominant fatty acid and phospholipids profiles placed the isolate HY-3 in the family Enterobacteriaceae. Further biochemical characterization and phylogenetic studies including determination of an almost complete 16S ribosomal DNA sequence suggested that the bacterium was closely related to the genus Serratia. DNA-DNA hybridization analysis revealed that this extracellular protease-producing strain belongs to Serratia proteamaculans, which is also known far its association with insects.

• Resources Recycling
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• v.14 no.6 s.68
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• pp.21-27
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• 2005

As one of the hydrometallurgical processes available in the recycling of silver-bearing wastes, the preparation of Ag nano-powder was investigated by a reductive precipitation reaction in silver solution using sodium formaldehydesulfoxylate and ascorbic acid as a reducing agent. Silver solution was prepared by dissolving silver nitrate with distilled water, and Tamol NN8906, PVP, SDS and caprylic acid were also used respectively as the dispersant to avoid the agglomeration of particles during the reductive reaction. Ag particles obtained from the reduction reaction from silver solution were characterized using the particle size analyzer and TEM to determine the particle size distribution and morphology. It was found that about $40\%$ excess of sodium formaldehydesulfoxylate was required to reduce completely silver ions in the solution. It alto appeared that the particle size generated with sodium formaldehydesulfoxylate was much greater than that with ascorbic acid. As far as the effect of dispersant on the Ag particles was concerned, the particle size distribution showed typically bimodal distribution in case of Tamol/FVP while very broad distribution ranged from 0.01 to $100{\mu}m$ appeared in case of SDS/caprylic acid.

• Journal of Applied Biological Chemistry
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• v.49 no.1
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• pp.28-32
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• 2006

Effect of organic-C on immobilization and nitrification patterns in acidic soil was examined during 20 weeks incubation period to verify if organic amendments such as composted material can increase soil retention of N by stimulating microbial immobilization of $NH_4^+$. Four treatments were laid out: control without fertilizer N and glucose (treatment code: S), ammonium sulfate (SN), ammonium sulfate with single glucose at the commencement (0 week) of incubation (SNG), and ammonium sulfate with double glucose at 0 and 4 weeks of incubation (SNGG). Glucose application (SNG) significantly increased microbial immobilization of $NH_4^+$ within 1 week of incubation over SN. Immobilization was followed by remineralization thereafter; however, second-application of glucose (SNGG) restored $NH_4^+$ immobilization. At the same time, nitrification was significantly inhibited by glucose application as indicated by consistently low $NO_3^-$ concentration in SNG and SNGG soils, suggesting that microbial assimilation of $NH_4^+$ is predominant compared to nitrification when available C-source is abundant. These results suggest application of chemical fertilizer-N with organic amendment would have beneficial effect on soil-N retention and environmental conservation by reducing production of $NO_3^-$ which is likely to be lost through leaching or denitrification.