• Journal of Life Science
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• v.18 no.9
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• pp.1194-1201
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• 2008

Water temperature-dependent fluctuations of biochemical and molecular activities in the harmful dinoflagellate, Cochlodinium polykrikoides were studied. In terms of genomic DNA concentration, a similar value of 0.6 was observed at $12^{\circ}C$ and $15^{\circ}C$. However, DNA significantly increased beyond $18^{\circ}C$ (p<0.05), to a maximum of 1.8 at $24^{\circ}C$. DNA concentration significantly decreased to 0.6. The concentrations of RNA and total protein were likely at their highest values of 1.7 and 0.07 ${\mu}g$ $ml^{-1}$ at $24^{\circ}C$, respectively. RNA and total protein concentrations began to increase at $15^{\circ}C$. Oxygen availability between lower and higher temperatures was significantly different and increased from $18^{\circ}C$ according to light intensity, regardless of wavelengths (p<0.05). At $24^{\circ}C$, the highest value of the maximum electron transport rate ($ETR_{max}$), ranging from 537.9 (Ch 1) to 602.5 ${\mu}mol$ electrons $g^{-1}$ Chl ${\alpha}s^{-1}$ (Ch 4), was also apparent. Nitrate reductase (NR) and ATPase activities were at their highest values of 0.11 ${\mu}mol$ $NO_{2}^{-}$ ${\mu}g^{-1}$ Chl ${\alpha}h^{-1}$ and 0.78 pmol 100 $mg^{-1}$ at $24^{\circ}C$, respectively. In an analysis of CHN, the concentration of C and N also significantly increased (p<0.05). Most of the measurements for the cellular activities at $27^{\circ}C$, however, were less than at $24^{\circ}C$. These results suggest that the sub-cellular activities of C. polykrikoides are sensitive to changes in water temperature. It may be desirable to estimate at $18^{\circ}C$ the initiation of the massive blooming development of C. polykrikoides. In nature, it will be very difficult to maintain the massive blooms beyond $24^{\circ}C$ because of a possibly significant decrease in molecular activity of C. polykrikoides.

• Korean Journal of Environmental Biology
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• v.38 no.3
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• pp.404-415
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• 2020

We investigated the seasonal variations in growth and physiological responses of the kelp species Ecklonia cava to different nitrogen sources to establish indoor culture conditions for mass production. Ecklonia cava was cultivated for 10 days in 16 combinations of seawater temperatures (15, 17, 21, and 25℃) and different nitrogen sources (control; NH-NH₄⁺ 100 μM; NO-NO₃^- 100 μM; and NHNO-NH₄⁺ 50 μM+NO₃^- 50 μM). The growth and growth rate of the blade were affected by temperature. The mean fresh weight and area-based daily growth rate were the highest (5.8±0.5 and 6.6±0.5% day^-1, respectively) at 15℃ and the lowest (2.2±0.2 and 3.0±0.3% day^-1, respectively) at 25℃. The daily growth rate was the highest in the NH and NO treatments and lowest in the control. The nitrate reductase activity of E. cava varied with water temperature (season). The highest activity was in the control (1.32±0.10 μmol NO₂^- g^-1 dry weight h^-1) and the lowest was in the NH treatment (0.25±0.02 μmol NO₂^- g^-1 dry weight h^-1). The photosynthetic pigment concentrations reached a maximum value in the NHNO treatment and a minimum value in the control. These results showed that water temperature played an important role in the cultivation of E. cava and that a single supply of NH₄⁺ or NO₃^- may induce the accelerated growth of E. cava. The growth and physiological responses of E. cava to different nitrogen sources during each season provide valuable information for determining the optimal nitrogen source in E. cava cultivation under indoor conditions.

• Journal of Korean Society of Environmental Engineers
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• v.29 no.8
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• pp.895-903
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• 2007

As for the increasing demanding on the development of direct-ecological landfill monitoring methods, it is needed for critically defining the condition of landfills and their influence on the environment, quantifying the amount of enzymes and bacteria mainly concerned with biochemical reaction in the landfills. This study was thus conducted to understand the fates of contaminants in association with groundwater quality parameters. For the study, groundwater was seasonally sampled from four closed unsanitary landfills(i.e. Cheonan(C), Wonju(W), Nonsan(N), Pyeongtaek(P) sites) in which microbial diversity was simultaneously obtained by 16S rDNA methods. Subsequently, a number of primer sets were prepared for quantifying the specific gene of representative bacteria and the gene of encoding enzymes dominantly found in the landfills. The relationship between water quality parameters and gene quantification were compared based on correlation factors. Correlation between DSR(Sulfate reduction bacteria) gene and BOD(Biochemical Oxygen Demand) was greater than 0.8 while NSR(Nitrification bacteria-Nitrospira sp.) gene and nitrate were related more than 0.9. A stabilization indicator(BOD/COD) and MTOT(Methane Oxidation bacteria), MCR(Methyl coenzyme M reductase), Dde(Dechloromonas denitrificans) genes were correlated over 0.8, but ferric iron and Fli(Ferribacterium limineticm) gene were at the lowest of 0.7. For MTOT, it was at the highest related at 100% over BOD/COD. In addition, anaerobic genes(i.e., nirS-Nitrite reductase, MCR. Dde, DSR) and DO were also related more than 0.8, which showing anaerobic reactions generally dependant upon DO. As demonstrated in the study, molecular biological investigation and water quality parameters are highly co-linked, so that quantitative real-time PCR could be cooperatively used for assessing landfill stabilization in association with the conventional monitoring parameters.

• Journal of Food Hygiene and Safety
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• v.26 no.3
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• pp.222-226
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• 2011

Salmonellosis is a major bacterial zoonosis that causes self-limited enteritis to fatal infection in animals and food-borne infection and typhoid fever in humans. Multidrug-resistant strains of Salmonella spp. has increased over the last several decades and recently causes more serious problems in public health. The present study was investigated bacteriocidal effects of sodium chlorate, sodium azide, sodium cyanide, and sodium salts mixture containing sodium chlorate, sodium azide, and sodium cyanide on infection with S. typhimurium in macrophage RAW 264.7 cells, and antibacterial effects of sodium salts mixture for murine salmonellosis. In infection assay of S. typhimurium in RAW 264.7 cells, bacterial survival rates within macrophage in all treated groups was significantly reduced comparing to that of the control group with the passage of incubation time. Administration of sodium salts mixture showed a therapeutic effect for S. typhimurium infected ICR mice. The mortality of mice treated with sodium salts mixture was 70% until 12 days, while that of control mice was 100% until 9 days after S. typhimurium infection. The results of this study strongly indicate that sodium salts mixture has a potency treatment for murine salmonellosis.

• Korean Journal of Agricultural and Forest Meteorology
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• v.5 no.3
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• pp.172-178
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• 2003

This study was conducted to assess the physiological tolerance of native tree species for successful restoration and revegetation of abandoned coal-mine spoils. Study sites were two coal-mine spoils (Sododong and Ssarijae) in Taebaek, Kangwon Province, Korea. Five individuals of Betula costata and of B. schmidtii were analyzed for malondialdehyde (MDA) and hydrogen peroxide ($H_2O$$_2$) content, nitrate reductase (NR) and superoxide dismutase (SOD) activity, and for carbohydrate concentration in the leaves. Trees in the abandoned coal-mine spoils were influenced by deficiencies expressed by MDA and $H_2O$$_2$ content in the leaves of two species being higher at the coal-mine spoils than in the surrounding forest. Low NR activity indirectly represented nitrogen deficiency in the soil of the coal-mine spoils; an unmanageable SOD activity implied that tolerant functions didn't net against a certain stress of the coal-mine spoils. Decreased glucose and increased starch concentration especially showed the inhibition of the carbohydrate metabolism by inadequate factors. Consequently, low nitrogen content in the real-mine soils might increase damage in trees as a result of inhibiting the expression of tolerance mechanisms against stress. Therefore, trees in coal-mine spoils need ample nitrogen to use as a metabolic energy source in order to prevent damage and increase tolerance against stress.

• Korean Journal of Environment and Ecology
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• v.26 no.6
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• pp.902-910
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• 2012

This study has been carried out to determine the effects of disturbances from wild boar grubbing on the functions of ecosystem. The experiments was performed in Mt. Jumbong of Long-term Ecological Research Sites of the Ministry of Environment. We measured soil physical properties, soil respiration($CO_2$), microbial biomass C, and soil enzyme activities from both disturbed and control plots. The disturbance sites were divided into two parts, mounds and pits. Soil organic matter contents were highest value at the control plots and lowest at the pit plots, respectively at 20.22% and 15.52%. The soil bulk densities were highest at the pit plots. Soil microbial biomass C and $CO_2$ evolution were significantly higher at the control plots compared to the disturbed plots. The results were positively correlated with soil organic matter contents. The cellulase activity and invertase activity in the soil showed similar pattern as the microbial biomass C and $CO_2$ evolution results. The cellulase activity and invertase activity in the soil were positively correlated with soil microbial biomass C. Soil organic matter contents seemed to affect the soil enzyme activities. The nitrate reductase activities were highest at the pit plots, which showed positive correlation with soil bulk density. The study results showed that the grubbing disturbances by wild boars induced the changes in soil properties, which affected soil microbial activities.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.32 no.4
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• pp.392-402
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• 1987

To know the effect of presowing seed soaking with some growth substances (kinetin, IAA, ethrel and salicylic acid) on vegetative growth and yield contributing parameters in soybean [Glycine max (L.) Merrill] the investigation was undertaken. The salient features from the study are;-All the treatments showed the enhancement effect on vegetative growth, viz. seediling emergence, germination percentage, plant height, number of leaves and branches per plant as compared with control, whereas salicylic acid delayed the seedling emergence process and lowered the germination percentage.-Nodule initiation, number of nodules and nodule weight were hastened and increased respectively under all the treatments whereas IAA showed an opposite effect on all the parameters at the early stages of nodule development.-Kinetin, IAA and ethrel showed the significant enhancement effect on the levels of biochemical parameters throughout the time of seed development whereas salicylic acid and water showed the tendency similar to that of control.-Yield and its components, viz. number of flowers, pods and seeds per plant were significant increased under all the treatments but they didn't show any significant enhancement effect on number of seeds per pod and pod setting rate. One hundred seed weight was lower under all the treatments, indicating the dilution effect resulting from incapability of increased number and size of source to provide the increased size of sink with assimilates.

• Journal of The Korean Society of Grassland and Forage Science
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• v.5 no.2
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• pp.121-126
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• 1985

Phytotron and field experiments were conducted to determine the influence of morphological growth stage and environmental temperature on synthesis and accumulation pattern of cyanogenic glycosides in sorghum cv. Pioneer 931 and Sioux at Munich technical university from 1979 to 1980. Various growth stages of sorghum plants were grown in phytotron at 4 different temperature regimes of 30/25, 25/20, 28/18 and 18/8 degree C with 35,000 Lux over 13-h days. The results obtained are summarized as follows: 1. Cyanogenic glycosides in sorghum plants were shown to have a great synthetic rate at early growth stages. The highest concentrations of hydrocyanic acid (HCN) were found at 2-leaf stage with 2384 and 1800ppm (DM basis) for Pioneer 931 and Sioux respectively. The contents of HCN were, however, however decreased markedly as morphological development, which shows a value of 173ppm (Pioneer 931) and 70ppm (Sioux) at heading stages. 2. Changes of hydrocyanic acid in sorghum plants were positive correlated with leaf weight ratio and leaf area ratio ($P{\leqq}0.1%$), while plant height shows a negative correlation with HCN contents ($P{\leqq}0.1%$). 3. Cyanogenic glycosides were accumulated in young plants mainly in leaves. During the late maturities, the contents of HCN in leaves and stalks were shown, however, a similar distribution. 4. Synthesis rates of cyanogenic glycosides were increased under high temperature. Accumulated hydrocyanic acid in the plants was, however declined when temperature exceeded 30 degree C. 5. Synthesis rates of cyanogenic glycosides were affected by nitrogen reductase activity (NRA). The concentration of hydrocyanic acid in sorghum plants was associated with increasing of nitrate-N accumulation.

• KSBB Journal
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• v.29 no.4
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• pp.285-296
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• 2014

Although the problems of the algal blooms have been world-widely observed in freshwater, estuary, and marine throughout the year, it is not yet certain what are the basic causes of such blooms. Consequently, it is very difficult to predict when and where algal blooms occur. The constituents of the Asian dust are in a good agreement with the elements required for the algal growth, which suggests some possible relationship between the algal blooms and the Asian dust. There have been frequently algal blooms in drinking water from rivers or lakes. However, there is no any algal blooms in upwelling waters where the Asian dust cannot penetrate into the soil due to its relatively weak settling velocity (size of particles, $4.5{\pm}1.5{\mu}m$), which implies the possible close relationship of the Asian dust with algal blooms. The present initiative study is thus intended firstly in Korea to illustrate such a relationship by reviewing typical previous studies along with 12 years of weekly iron profiles (2001~2012) and two slant culture experiments with the dissolved Asian dust. The result showed bacterial suspected colonies in the slant culture experiment that are qualitatively in a good agreement with the recent Japanese studies. Since the diatoms require cheap energy (8%) compared to other phytoplankton (100%) to synthesize their cell walls by silicate, the present results can be used to predict algal blooms by diatoms if the concentrations of iron and silicate are available during spring and fall. It can be postulated that the algal blooms occur only if the environmental factors such as light, nutrients, calm water surface layer, temperature, and pH are simultaneously satisfied with the requirements of the micronutrients of mineral ions supplied by the Asian dust as enzymatic cofactors for the rapid bio-synthesis of the macromolecules during algal blooms. Simple eco-friendly methods to regulate the algal blooms are suggested for the initial stage of blooming with limited area: 1) to cover up the water surface with black curtain and inhibit photosynthesis during the day time, 2) to blow air (20.9%) or pure oxygen into the bottom of the water and inhibit rubisco for carbon uptake and nitrate reductase for nitrogen uptake activities in algal growth during the night, 3) to eliminate the resting spores or cysts by suction of bottom sediments as deep as 5 cm to prevent the next year germinations.

• Korean Journal of Soil Science and Fertilizer
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• v.22 no.4
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• pp.329-336
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• 1989

A series of green house experiment was conducted to find but the effect of fertilizer application and inoculation of rhizobium on the changes of amide-N, ureide-N and $NH_4-N$ concentration in stem and root exudates of soybean plant growth. The results obtained were summarized as follows ; 1. Five strains of indigenous Rhizobium japonicum-nitrogen fixing activity($C_2H_2$-reducing activity) was more than 6.4 to 20.1 nmole/hr/tube-were identified from 37 soil samples in 22 areas of farmers field throughout country. 2. These identified 5 strains of rhizobium were obtained high nitrate reductase but low ammonium and nitrite oxidase activities. Among 5 strains of rhizobium the Rhizobium japonicum RjK-134 was applied for this green house experiment. 3. Dry matter yield was increased by the combination of inoculation of Rhizobium japonicum RjK-134 with no fertilizer and without nitrogen fertilizer application. However, dry matter yield was decreased with application of N and NPK with inoculation of rhizobium. 4. The concentrations of amide-N and ureide-N were increased in xylem sap than that of root exudate and higher concentration was obtained ar 30 days after planting than flowering stage (45 days after planting). 5. The combination of NPK application with inoculation of Rhrizobium japonicum RjK-134 enhanced the increase of amide-N and ureide-N concentration in xylem sap and root exudate. 6. High ammonium-N concentration in xylem sap and root exudate were obtained in combination with without-fertilizer under no inoculation of rhizobium and N and NPK application with inoculation of rhizobium.