• Magazine of the Korean Society of Agricultural Engineers
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• v.44 no.3
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• pp.136-145
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• 2002

Monitoring data from agricultural reservoirs throughout the country were analyzed to evaluate the limiting factor fur algal growth and relationships between Chl-a, total phosphorus (TP), and total nitrogen (TN). Total 394 reservoirs ranging from below 500 ㎥ to over 50 million ㎥ in storage volume were monitored from 1990 to 2000 with respect to TP, W, Chl-a, and their annual mean values were used fur the analysis. Based on N/P ratio, the dominant limiting factor for algal growth was turned out to be phosphorus in agricultural reservoirs (about 83%). Therefore, the proper managements of phosphorus in the agricultural watershed appear to be crucial to prevent excessive on algal growth. The effects of phosphorus and nitrogen ware most eminent during the summer period. And the effect of nutrients on the algal biomass (Chl-a) development appeared to be greater in smaller the reservoirs than in larger ones. Generally, Chl-a and TP demonstrated a close relationship while that of Chl-a and TN showed less correlationship. Chl-a and chemical oxygen demand (COD) also showed a good relationship. Beth ratios of Chl-a / TP and Chl-a / COD relationships were within the range of literature values. Quantitative analysis of TP and COD is relatively convenient compared to that of Chl-a, and the relationship between TP and COD and Chl-a from this study could be used beneficially for water quality management of agricultural reservoirs and related water quality modeling.

• Environmental Sciences Bulletin of The Korean Environmental Sciences Society
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• v.3 no.3
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• pp.177-188
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• 1999

The effect of ABA on the chloroplast disassembly of Zea mays was investigated by measuring the changes in the relative distribution of chlorophyll(Chl) between the Chl-protein complexes in ABA treated and untreated sensecting leaves. The reaction center(RC)-light harvesting complex(LHC) regions were rapidly disassembled in the late stage of dark-induced senescence. Plus, during dark-induced senescence, the disassembly of a reaction center of P700 apoproteins containing mainly Chl a was faster than that of a reaction center of LHCI apoproteins containing both Chl a and Chl b. The increase in the relative distribution of Chl-protein complexes in the RC-Core2 in the late stage of senescence was due to the accumulation of core complexes such as CP47/43 and reaction centers including D1/D2 apoproteins disassembled from the RC-Corel containing the dimer of D1/D2 apoproteins. The LHCII region was more stable than the other Chl-protein complexes throughout leaf senscence. Accordingly, it is suggested that the preferential breakdown of Chl a gives rise to the disassembly of Chl a-binding proteins, particularly reaction centers and core complexes during dark-induced senescence, plus the primary target of the photosynthetic apparatus in sensecing leaves would seem to be Chl a along with the proteins associated with Chl a. The application of ABA promoted the disassembly of the P700 apoproteins in the PSI reaction center and the dimer of D1/D2 apoproteins, and the conversion of the trimeric LHCII apoprotein to the monometirc LHCII apoprotein during the middle stage of leaf senescence, thereby suggesting that ABA accelerates the disassembly of both Chl a-binding and Chl a+b-binding proteins, particularly Chl a-binding proteins during the middle stage of leaf senescence.

• YAKHAK HOEJI
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• v.35 no.2
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• pp.111-118
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• 1991

A comparative study was performed on two different strains of Leishmania major, chloroquine sensitive strains (Chl$^{S}$) and its mutant chloroquine resistant strains (Chl$^{R}$). Chl$^{R}$ strains were obtained at 5$\times$$10^{-4}$M chloroquine. Remarkable differences were observed at the initial chloroquine uptake in Chl$^{R}$ and Chl$^{S}$, i.e., the rate of uptake was very reduced in Chl$^{R}$ (Km values were 70 nM and 125 nM, respectively). Influx and accumulation of chloroquine were also compared between wild type and mutant. An increasing tendency in both influx and accumulation of chloroquine was shown in Chl$^{S}$, but Chl$^{R}$ demonstrated a rapid release after a little uptake (influx) at the early stage. This result is thought to be basis of their resistance for Chl$^{R}$ strains.

• KCID journal
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• v.18 no.1
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• pp.25-32
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• 2011

In order to effectively manage the reservoir, reservoir water quality management should be based on physicochemical and configurational characteristics. In this research, correlation between factors affecting the reservoir water quality was examined. Chl-a and COD shows the highest positive correlation. Chl-a and T-P also has a high positive correlation, however Chl-a and T-N show lower correlation relatively. Even though T-N is an important factor for phytoplankton growth which increase Chl-a concentration, corelation of Ch1-a and T-N shows that enough nitrogen in the reservoir isn't no longer limiting factor. The age of reservoir can cause of increasing COD and SS. Embankment height and elevation of reservoirs shows strong negative correlation to water quality. That means reservoir which is higher embankment height and locate in higher elevations is less contaminated. Regression expression was derived with Chl-a and water quality parameters, and height of reservoir. Finally Chl-a was simulated using regression expression and it was a good approach to predict the Chl-a concentration.

• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 2005.10a
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• pp.626-631
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• 2005

Monitoring data from agricultural reservoirs throughout the country were analyzed to evaluate the limiting factor for algal growth and correlationship between Chl-a, total phosphorus (TP), total nitrogen (TN), and chemical oxygen demand (COD). It was used for the analysis to monitored data of 394 reservoirs such as TP, TN, Chl-a, and COD from 1999 to 2003. This study analyzed water quality items in terms of areas, seasons. It turned out that phosphorus in agricultural reservoirs (about 80%) was dominant limiting factor for algal growth. Therefor, it appears that the appropriate managements of phosphorus in the agricultural watershed are crucial to prevent excessive on algal growth. Generally, there is correlation between Chl-a and TP while Chl-a do not have effect on TN. Also, Chl-a have influence on COD. This study could be used beneficially for water quality management of agricultural reservoirs and related water quality modeling.

• Journal of the Korean Chemical Society
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• v.26 no.5
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• pp.304-309
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• 1982

The fluorescence yields of chl-a and-b complexes bound to silicon dimer, tetramer and hexamer containing pyridine group in diethyl ether solvent, were shown the transition of excited energy through silicon polymer chain, and the maximum energy quenching were appeared at 1 : 1 ratio of chl-a and pyridine group in silicon polymer but the chl-b complexes were shown the maximum energy of fluorescene emission at the same ratio.

• Korean Journal of Environmental Agriculture
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• v.33 no.4
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• pp.344-349
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• 2014

BACKGROUND: Purpose of the study was to establish the extinction coefficients of chlorophyll a and b in N,N-dimethylformamide(DMF) and Dimethylsulfoxide(DMSO) solvents and to find out the conditions of optimal extraction temperature and time in citrus leaves. METHODS AND RESULTS: Chlorophyll a and b standards were dissolved in DMF and DMSO. Extinction coefficients of chlorophyll pigments were determined and their contents were quantified using spectrophotometer. Chlorophyllous pigments of citrus(Citrus unshiu Marc. cv. Okitsu wase) leaves were extracted at 25, 40, 60 and $80^{\circ}C$ for 4, 6, 8, 24 and 48 hours to determine the optimal extraction condition. CONCLUSION: The extinction coefficients of chlorophyll a(Chl a) and chlorophyll b(Chl b) of DMF extracts for high extinction wavelength were 663.8 and 647.2 nm. Similarly, the high extinction wavelength of DMSO extracts were 665.8 and 649.0 nm for chl a and b respectively. Chl a, Chl b and total chlorophyll content of DMF extracts were Chl a = $12.10A_{663.8}-2.74A_{647.2}$, Chl b = $21.94A_{647.2}-5.06A_{663.8}$ and total $Chl=19.193A_{647.2}+7.04A_{663.8}$. Similarly, Chl a, Chl b and total Chl of DMSO extracts were Chl a = $14.53A_{665.8}-5.40A_{649.0}$, Chl b = $26.98A_{649.0}-7.11A_{665.8}$ and total $Chl=21.58A_{649.0}+7.43A_{665.8}$. The chlorophyll extracts of DMF and DMSO were very stable in dark. High chlorophyll contents of citrus leaves were found at $80^{\circ}C$ extraction for 6 hours in DMF and at $80^{\circ}C$ extraction for 24 hours in DMSO. However, the chlorophyll content was decreased significantly after 8 hours in DMF extraction while it was remained up to 30 hours in DMSO extraction.

• Journal of Microbiology and Biotechnology
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• v.26 no.5
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• pp.959-966
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• 2016

Chlorophyll synthase (ChlG) and bacteriochlorophyll synthase (BchG) have a high degree of substrate specificity. The BchG mutant of Rhodobacter sphaeroides, BG1 strain, is photosynthetically incompetent. When BG1 harboring chlG of Synechocystis sp. PCC 6803 was cultured photoheterotrophically, colonies arose at a frequency of approximately 10^-8. All the suppressor mutants were determined to have the same mutational change, ChlG_I44F. The mutated enzyme ChlG_I44F showed BchG activity. Remarkably, BchG_F28I, which has the substitution of F at the corresponding 28^th residue to I, showed ChlG activity. The K_m values of ChlG_I44F and BchG_F28I for their original substrates, chlorophyllide (Chlide) a and bacteriochlorophyllide (Bchlide) a, respectively, were not affected by the mutations, but the K_m values of ChlG_I44F and BchG_F28I for the new substrates Bchlide a and Chlide a, respectively, were more than 10-fold larger than those for their original substrates, suggesting the lower affinities for new substrates. Taken together, I44 and F28 are important for the substrate specificities of ChlG and BchG, respectively. The BchG activity of ChlG_I44F and the ChlG activity of BchG_F28I further suggest that ChlG and BchG are evolutionarily related enzymes.

• Korean Journal of Environmental Biology
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• v.41 no.1
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• pp.89-100
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• 2023

We investigated the spatial distribution of heterotrophic bacteria associated with different water masses in the northern East China Sea(ECS) in summer. The surface water masses were divided into the Changjiang Diluted Water (CDW) and high salinity water (HSW). In the CDW region, the concentrations of dissolved inorganic nitrogen (DIN) and chlorophyll-a (Chl-a), and micro Chl-a contribution were high; and bacterial abundance (BA) and ciliate abundance (CA) were also high. In the HSW region with relatively low DIN concentrations, Chl-a concentration and micro Chl-a contribution were low, but pico Chl-a contribution was increased compared to those in the CDW region. BA did not show any significant difference from the CDW region, but CA was decreased. BA showed a positive correlation with Chl-a concentration in the CDW region; however, it did not show a significant correlation with Chl-a concentration in the HSW region. The ratio of bacterial carbon biomass/phytoplankton carbon biomass was exponentially increased with a decrease in the Chl-a concentration. Compared to the past (1990-2000s), the surface phosphate concentrations and the size of dominant phytoplankton have recently decreased in the ECS. Considering this trend of nutrient decrease and miniaturization of the phytoplankton, our results indicate that changes in the strength of the oligotrophic water mass could alter the function of the microbial food web.

• Journal of Aquaculture
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• v.19 no.4
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• pp.310-314
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• 2006

This study was carried out to investigate grazing of brackish water cyclopoid copepod Paracyclopina nana on four microalgae species (Tetraselmis suecica, Isochrysis galbana, Phaeodactylum tricornutum and Dunaliella tertiolecta) and different food concentrations raging from 5 to 55 ng chl a/ml. The grazing of P. nana was examined by the analysis of decreased number of microalgae and chlorophyll a content in rearing water and pigment content in the gut of P. nana. The maximum content of decreased chlorophyll a and gut pigment in P. nana varied with microalgae species and concentrations. It appeared at the food concentration 30 ng chl a/ml in T. suecica, 40 ng chl a/ml in I. galnaba and D. tertiolecta, and 45 ng chl a/ml in P. tricornutum, respectively. The grazing rate of a P. nana per hour also varied with different microalgae species and concentrations. The maximum grazing rate per hour of P. nana fed T. suecica with 39.3 ng chl a/ml was the highest with 0.63 ng chl a/h, but lowest with 0.52 ng chl a/h. From these results, it can be concluded that T. suecica is the best species among four microalgae species for the mass culture of P. nana and daily optimum food concentration of P. nana is $25{\sim}39$ ng chl a (approximately $10{\sim}15{\times}10^4$ cells).