• Journal of the Korean Chemical Society
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• v.25 no.4
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• pp.275-282
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• 1981

A simple semiquantitative procedure was developed for the determination of sub-ppm level of chromium(VI) in aquatic samples by using an analytical micro-column packed with diphenylcarbazide(DPC) gel beads. DPC gel beads were prepared by swelling XAD-2 resin(115∼150 mesh in dry condition) in ethanol for 10min, packing into a glass column(1.5 mm bore, 65nm length) and adsorbing 1ml of ethanol solution of $2{\times}10^{-3}M$ DPC for 20min at room temperature. When 0.5ml of ethanol solution containing chromium(VI) was passed through the DPC gel column for 40min, the original white color of the reagent gel turned to red-violet from the up-stream of the column. As the length of colored band was proportional to the total amount of chromium(VI) in the sample solution passed through the column, the concentration of chromium(VI) could be determined from the calibration line which had been prepared by using the standard solution. Chromium(VI) ion as small as from 0.1 to 0.8 ppm could be determined with ${\pm}5{\sim}{\pm}15{\%}$ relative errors. Since other interfering cations were few, 100-fold excess of Fe(III), 50-fold excess of Cu(II) could be masked with EDTA. This method was successfully applied to the analysis of chromium(VI) in industrial effluents.

• Journal of Life Science
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• v.31 no.6
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• pp.574-580
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• 2021

This study investigated the pathogenicity of different genotypes of infectious hematopoietic necrosis virus (IHNV) strains isolated from infected rainbow trout in Gangwon Province. RtPc0314c and RtPc0314g strains belonging to the JRt-Shizuoka lineage and RtPc0816g strain belonging to the JRt-Nagano lineage showed 100% cumulative mortality when inoculated at a high titer. In addition, more rapid necrosis was observed in rainbow trout infected with RtPc0314c and RtPc0314g mutations. When inoculated at a low titer, 100% mortality was not observed until the end of the experiment, but the mortality was higher in rainbow trout infected with a mutant strain belonging to the JRt-Shizuoka linage than a mutant strain belonging to the JRt-Nagano lineage. A histopathological analysis showed a clear signature of infection in kidney and spleen tissues upon infection with RtPc0314c and RtPc0314g but no signature of infection associated with the Rt03186 strain. Based on the results in this study, it seems that strains belonging to the JRt-Shizuoka lineage in Gangwon Province IHNV are more pathogenic.

• Journal of Applied Biological Chemistry
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• v.65 no.4
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• pp.405-412
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• 2022

Echinodorus cordifolius (L.) is an aquatic plant in the family Alismataceae. The anti-skin aging activity of E. cordifolius (L.) has not been yet reported. Therefore, the objective of the present study was to prepare 70% ethanol extract (ECEE) from E. cordifolius (L.) and investigate their antioxidant and anti-hyaluronidase activities for confirm the potential of anti-skin aging. ECEE showed good activities of DPPH, hydrogen peroxide scavenging, and hyaluronidase inhibition, with EC₅₀ and IC₅₀ values of 31.4, 300, and 450 ㎍/mL, respectively. ECEE also significantly improved cell viability and inhibited intracellular reactive oxygen species dose-dependently against 1 mM hydrogen peroxide-induced oxidative stress in immortalized human keratinocytes (HaCaT cells). Furthermore, ECEE upregulated hyaluronic acid (HA)-synthesizing enzyme hyaluronan synthase 2 (HAS2) expression level, but downregulated expression level of HA-degrading enzyme hyaluronidase 2, resulting in increased HA production in HaCaT cells. Taken together, these results suggest that ECEE shows antioxidant and anti-hyaluronidase potential and could be a functional cosmetic ingredients for anti-skin aging.

• Bulletin of the Korean Chemical Society
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• v.27 no.7
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• pp.1015-1019
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• 2006

The peptide with structural similarity to mammalian substance P (M-SP) has been isolated from extract of the body of the African lungfish, Protopterus dolloi, using the rectum of the newt as the bioassay system. The primary structure of the SP-related peptide was identified as Lys-Pro-Arg-Pro-Asp-Gln-Phe-Tyr-Gly-Leu-Met-NH2 (L-SP) and contained four substitutions ($Lys^{1}\rightarrow $ Arg, $Arg^{3}\rightarrow$ Lys, $Asp^{5}\rightarrow$ Gln, and $Tyr^{8}\rightarrow$ Phe) compared with M-SP; this structure is identical to that of the peptide isolated from the gut of the Australian lungfish. Circular dichroism spectra showed that L-SP had an unordered structure in the buffer solution and phospholipid bilayers. This peptide was found to have an excitatory effect on rectal muscle tissues of newt, quail, and fish. L-SP also had a more potent vasodilatory effect on the guinea-pig aorta than that of M-SP. The identification of the peptide provides evidence that SP family, hitherto confined to mammals, have a widespread occurrence in lungfish.

• Biotechnology and Bioprocess Engineering:BBE
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• v.9 no.4
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• pp.267-273
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• 2004

The optimization of culture conditions for the bacterium Pseudomonas aeruginosa BYK-2 KCTC 18012P, was performed to increase its rhamnolipid production. The optimum level for carbon, nitrogen sources, temperature and pH, for rhamnolipid production in a flask, were identified as 25 g/L fish oil, 0.01% (w/v) urea, 25 and pH 7.0, respectively. Optimum conditions for batch culture, using a 7-L jar fermentor, were 200 rpm of agitation speed and a 2.0 L/min aeration rate. Under the optimum conditions, on fish oil for 216 h, the final cell and rhamnolipid concentrations were 5.3 g/L and 17.0 g/L respectively. Fed-batch fermentation, with different feeding conditions, was carried out in order to increase, cell growth and rhamnolipid production by the Pseudomonas aeruginosa, BYK-2 KCTC 18012P. When 2.5 g of fish oil and 100 mL basal salts medium, containing 0.01 % (w/v) urea, were fed intermittently during the fermentation, the final cell and rhamnolipid concentrations at 264 h, were 6.1 and 22.7 g/L respectively. The fed-batch culture resulted in a 1.2-fold increase in the dry cell mass and a 1.3-fold increase in rhamnolipid production, compared to the production of the batch culture. The rhamnolipid production-substrate conversion factor (0.75 g/g) was higher than that of the batch culture (0.68 g/g).

• Journal of Aquaculture
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• v.15 no.2
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• pp.87-93
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• 2002

To improve the efficiency of biological filters used for treating recycled wastewater of aquaculture, the conventional and advanced DynaSand Filters were tested. Applying the fluid mechanics and physical chemistry theories to wastewater treatment plant, the advanced filter focuses on detection of wastewater characteristics and automatic operation of DynaSand Filter to improve backwashing, oxygen transport, turbidity removal and continuous head loss. The Filter removes COD, ammonia, and suspended solids (SS), the major pollutants in aquaculture wastewater. The total volume of the DynaSand Filter is 70 L, while the working volume is 35 L per cycle. The removal efficiency of the advanced DynaSand Filter is 71 % for SS (as against 55 % for the conventional filter), 84 % for ammonia, 85 % for T-P, and 88 % for SRP.

• Journal of Aquaculture
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• v.15 no.2
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• pp.103-110
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• 2002

Diets containing 0.02 to 10.0% EM-fermented orange (EFO) were fed to Paralichthys olivaceus(8.5 g), which were reared in flow-through system for 16 weeks. Groups fed on diets containing 0.1 and 0.2% EFO grew significantly faster; their feed coefficient and daily feeding rate were also higher. The number of goblet cells present in the mid-intestine of the fish receiving dietary EFO was significantly more. Total cholesterol level in plasma of the fish fed with 0.02% EFO was lower. However, there was no significant difference in GOT and GPT among the groups receiving different levels of EFO.

• Bulletin of the Korean Chemical Society
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• v.35 no.2
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• pp.371-376
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• 2014

A novel three-phase hollow fiber liquid phase microextraction was developed for the determination of malachite green (MG) in environmental waters, which selected [BMIM][$PF_6$] mixed with 1% trioctylphosphine oxide (TOPO) as supported phase. Several parameters (accepter phase pH, sample pH, supported phase membrane, volume of accepter phase, salinity, extraction time) that could affect extraction performance were investigated. Under the optimal extraction conditions, the established approach showed excellent characters as: high enrichment factor (212), wide linear range ($0.20-100{\mu}gL^{-1}$), low detection limit ($0.01{\mu}gL^{-1}$), good reproducibility (RSD, 8.9%, n=5) and satisfactory recovery (84.0-106.2%). The method was applied to detect MG at Yangtze River and pond waters in Zhenjiang, Jiangsu province, and 4 sites among 15 sampling sites were found MG with the concentration of $1.73-11.06{\mu}gL^{-1}$, which confirmed that the proposed environmentally friendly method was simple and effective for monitoring MG in aquatic system.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.26 no.2
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• pp.120-132
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• 1993

A continuous hollow fiber membrane reactor(CHFMR) was developed and optimized for the production of yellowfin sole(Limanda aspera) skin gelatin hydrolysates using trypsin. The results were summerized as follows: The $K_m$ value of the CHFMR was 2.4 times higher than that of the batch reactor, indicating reduced enzyme affinity for the substrate. The $K_2$ value of the CHFMR was 8.5 times lower than that of the batch process, showing a significant reduction in trypsin activity in the CHFMR. The optimum operating conditions for the CHFMR process were $55^{\circ}C$, pH 9.0, flux 7.79 ml/min, residence time 77min, and trypsin to substrate ratio, 0.01(w/w) After operating for 60min under the above conditions, $79\%$ of the total amount of initial gelatin was hydrolysed. Enzyme leakage was observed through the 10,000 MWCO membrane after the 20min of reactor operation, while none occurred after 5hr. Total enzyme leakage was about $12.95\%$ at $55^{\circ}C$ for 5hrs. However, there was no apparent correlation between enzyme leakage and substrate hydrolysis. The membrane has a significant effect on trypsin activity loss for 60min of the CHFMR operation. The CHFMR operating with the membrane lost $34\%$ of the initial activity versus a $23\%$ loss of activity after 3hr in the continuous reactor lacking the hollow fiber membrane. The measurement of fouling property showed that relative flux reduction was $91\%$ and flux recover rate was $92\%$ at $10\%$ substrate solution. The productivity(378.85mg product/mg enzyme) of the CHFMR was more than 4 times higher than that of the batch reactor at $55^{\circ}C$.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.27 no.5
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• pp.482-494
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• 1994

Most of carotenoprotein complexes have been extracted by using buffered solutions. However, in this study carotenoprotein from the muscle of Blue mussel(Mytilus edulis) was extracted by a detergent such as Triton X-100. It was purified and characterized by $20\%$ (w/v) $(NH_4)_2SO_4$, DEAE-cellulose ion exchange and Sephacryl S-300 gel filtration. The carotenoprotein(${\lambda}_{max}=462nm$) had an approximate M. W. of 372KDa(gel filtration). SDS-PAGE analysis of the carotenoprotein indicated the presence of four polypeptides of 60KDa($23.70\%$), 46.9KDa($9.14\%$), 26KDa($49.14\%$) and 13KDa($18.02\%$). Carotenoprotein denaturated by treatment with SDS to a final concentration of $0.2\%$ (w/v) caused a hypsochromic shift of ${\lambda}_{max}$ from 462nm to 456nm. The carotenoprotein contained lipids as structure units. The amino acid composition of the carotenoprotein contained large essential amino acid amounts of $62.8\%$, and the content of threonine($35.9\%$) was higher than other amino acids, but histidine, methionine and proline were not present. In the carotenoprotein, the major fatty acids were $C_{16:4},\;C_{16:0},\;C_{20:5}\;and\;C_{22:6}$. The percentages of polyunsaturated fatty acids($62.4\%$) were higher compared to other fatty acids(saturated fatty acids $19.6\%$, monounsaturated fatty acids $18.0\%$). Carotenoid was extracted from the carotenoprotein by acetone and it was separated into five different components by preparative TLC(benzene:petroleum ether:acetone=69:17:14). The major components of carotenoid were mytiloxanthin($74.79\%$) and 3,4,3'- trihydroxy-7',8'-didehydro-${\beta}$-carotene($18.26\%$), and they were at least presented as prosthetic groups of carotenoprotein.