• Korean Journal of Fisheries and Aquatic Sciences
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• v.46 no.2
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• pp.154-159
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• 2013

The AOAC Mouse Bioassay method (MBA) has been widely used for routine monitoring of paralytic shellfish poisoning (PSP) for more than 50 years. However, this method has low sensitivity and experiences interference from other components in the extract. Also, ethical issues have been raised against the continued use of this live-mouse assay. To establish an alternative method for PSP analysis, we attempted to develop PSP analysis conditions using liquid chromatography-tandem mass spectrometry (LC-MS/MS). The LC-MS/MS analysis of reference material showed very reasonable accuracy, and the analysis time was just 15 min. However, the recovery rate of toxin spike samples using the LC-MS/MS analysis was 59.4-91.0%. We also attempted to remove the matrix effect using shellfish extracts, but recoveries of C1 and C2 did not improve. A comparison between the results of MBA and LC-MS/MS analysis revealed good correlations, with values of 0.8878 and 0.9211 for oyster and mussel matrices, respectively.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.53 no.3
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• pp.361-367
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• 2020

The objective of this study was to investigate the effect of lactic acid bacteria (LAB) fermentation on the antioxidant activity of kelp Saccharina japonica water extract. Three LAB strains that had exhibited superior antioxidant activity in a previous study were selected for the kelp fermentation starter. The antioxidant activity of the fermented extracts was analyzed during fermentation. After 48 h of fermentation, the extract-fermented Lactobacillus plantarum D-11 strains showed the highest antioxidant activity in terms of DPPH (2,2-diphenyl-2-picryl hydrazyl) radical scavenging, ABTS [2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid)] radical scavenging, oxygen radical absorbance capacity (ORAC) and fluorescence recovery after photobleaching (FRAP) assay. Furthermore, the analysis of total phenolic and flavonoid contents revealed that the enhanced antioxidant activity was mainly due to the increased antioxidant content from fermentation. Thus, this study suggests that probiotic LAB fermentation is an attractive approach for the development of various kelp fermentation products.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.39 no.6
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• pp.454-459
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• 2006

A simultaneous high-performance liquid chromatography assay method for amoxicillin and ampicillin in fish products was developed, evaluated, and validated by monitoring these antibiotics in fish samples obtained from aquaculture and distribution. The recovery rate of this method was higher than those of conventional methods and was 95.3-106.6% for amoxicillin and 81.4-92.4% for ampicillin. Our pretreatment procedure sufficiently removed or reduced materials affecting HPLC analysis, such as low-molecular-weight substances. The performance limit of this method was evaluated as 0.01 ppm of amoxicillin and ampicillin in fish muscle. Finally, 171 fish samples, including olive flounder (Paralichthys olivaceus), common sea bass (Lateolabrax japonicus), and black rock fish (Sebastes schlegeli) collected from fish farms in the coastal area between April and September 2005 were analyzed to evaluate the overall efficiency of the method and to monitor the actual of amoxicillin and ampicillin usage in fish farms. The results indicated that the developed method was suitable for analyzing amoxicillin and ampicillin in fish muscle, and determined that those antibiotics were being used for fish farming but were not detected in fish samples during the shipping and distribution stages.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.44 no.1
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• pp.45-49
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• 2011

As a first step toward identifying a new method for testing sea snail tissue for toxins, and thus prevent food poisoning due to the ingestion of contaminated snails, we measured the tetramine [$(CH_3)_4N^+$] contents of sea snails from the Korean coast using both liquid chromatography-tandem mass spectrometry (LC-MS/MS) and ion chromatography. For tetramine tested, good linearity ($r^2$ = 0.9996) was observed between the amounts in the injected samples and the peak areas of standard toxins, which ranged from 0.1 to 100 ng. The recovery (%) of tetramine from spiked tissue and mid-gut gland samples ranged from 84.0 to 95.3%. The quantitative results for tetramine using this method were in good agreement with the theoretical values. LC-MS/MS has both high sensitivity and selectivity, which makes it possible to measure trace quantities of tetramine in samples.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.47 no.2
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• pp.135-143
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• 2014

Exopeptidase active fractions from the hepatopancreas of the Argentina shortfin squid Illex argentinus, were obtained with acetone (AC 30-40%), ammonium sulfate (AS 60-70% saturation), anion exchange chromatography (AE-II, 0.2 M NaCl) and gel filtration chromatography (GF-I, 30-50 kDa) fractionation methods. A bitter peptide solution that has a bitterness equivalent to that of 2% glycylphenylalanine and prepared by tryptic hydrolysis of milk casein, was treated with the exopeptidase active fractions. The GF-I fraction was the best based on aminopeptidase activity (35.3 U/mg), percentage of recovery (30.7%) and a sensory evaluation (1.7). The amount of released amino acids increased as incubation time increased, and the bitterness of the enzyme reaction mixtures decreased. Incubation with the GF-I fraction for 24 h resulted in the hydrolysis of several peptides as revealed by the reverse-phase high performance liguid chromatography profile, with three peaks (3, 5 and 6) decreasing in area (%) and three peaks (1, 2 and 4) increasing in area (%). Therefore, the GF-I fraction appeared to be ideally suited to reduce bitterness in protein hydrolysates by catalyzing the hydrolysis of bitter peptides.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.33 no.3
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• pp.184-191
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• 2000

Gametogenesis and the reproductive cycle of the marsh clam, Corbicula leana(Prime} were investigated monthly Hyongsan estuary, Korea from January to December 1998 by histological observation. C. leana had separate sexes, and oviparous. The gonads were located between the sub-region of mid-intestinal gland in visceral cavity and reticular cennective tissue. The ovary and testis were composed of a number of ovarian and testicular tubules, respectively, Mature oocytes were characterized by germinal vesicles with nucleoli and their sizes ranged $70\;to\;80{\mu}m$ in diameter. A number of mesenchymal tissues and pigment granular cells were distributed in the growing oocytes and spermatocytes during early developmental stages. With the further development of gonad, these tissuse and cells gradually disappeared. The monthly changes in the fatness index were closely related to reproductive cycle. Minimun size for sexual maturity was reached over 10.0 mm in shell length. The reproductive cycle could be classified into 6 stages : multiplicative (March to April): early growing and growing (May to June), mature (July to August), spent (September), degenerative (October) and recovery (November to February).

• Korean Journal of Fisheries and Aquatic Sciences
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• v.39 no.2
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• pp.78-84
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• 2006

A high performance liquid chromatography assay method for spiramycin in fish muscle was developed. The developed method was evaluated and validated by monitoring spiramycin in olive flounder (Paralichthys olivaceus), black rock fish (Sebastes schlegeli) and in live conger eel (Anguilla japonica) in fish farms and distribution centers. Using the developed method, the recovery rate was up to 82.4-88.8%, which was higher than that of conventional methods (77.6-87.1%). In particular, the proposed sample treatment protocol was suitable for use with fish samples to remove low molecular weight materials and pigments that could interfere an accurate analysis. The prepared stock solution was very stable, and it remained chemically stable for 5 weeks at $4^{\circ}C$. The performance limit of the developed method for spiramycin acid in fish muscle was 0.05 ppm. One hundred thirty-four fish samples including olive flounder, black rock fish and live conger eel were analyzed to evaluate the overall efficiency of the modified method and to monitor the actual condition of spiramycin usage in fish farms. Olive flounder and black rock fish were collected from fish farms in coastal areas of Korea, and live conger eels were purchased from a fish market in the Busan area from September 2001 to March 2002. According to the overall performance of the developed method, it was considered suitable for the monitoring of spiramycin in fish muscle. The suggested method of analysis for spiramycin in fish muscle is registered in the Korean Official Methods of Food Analysis and is currently tieing utilized for fishery products inspection by the Korea Food and Drug Administration and the National Fisheries Products Quality Inspection Service.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.43 no.6
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• pp.623-628
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• 2010

The distribution of fluoroquinolones was investigated in the carp (Cyprinus carpio) and eel (Anguilla japonica) after an oral dose of 20 mg/kg body weight/day for 35 days. Blood samples were collected at 5 and 10 hours and 1, 2, 3, 5, 7, 9, 13, 20, 30, and 35 days after treatment. The fluoroquinolone concentrations were determined high- performance liquid chromatography with an ultraviolet detector. The recovery rates of fluoroquinolones in the fish samples ranged from 91.4-96.6, 91.2-96.5, and 90.4-98.6% for concentrations of 0.1, 0.5, and $1.0\;{\mu}g/g$, respectively. In the blood of carp, ciprofloxacin, enrofloxacin, norfloxacin, and sarafloxacin reached maximums level of 11.03, 9.37, 9.10, and $9.81\;{\mu}g/g$ 10 hours, 1 day, 10 hours, and 10 hours after treatment, respectively. In the eel blood, these reached maximum levels of 12.65, 11.18, 11.91, and $8.74\;{\mu}g/g$ all at 10 hours. Carp sample concentrations of ciprofloxacin, enrofloxacin, norfloxacin, and sarafloxacin were not measurable 20, 30, 20, and 20 days after treatment, respectively, in all experiments (

• Korean Journal of Fisheries and Aquatic Sciences
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• v.38 no.6
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• pp.372-378
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• 2005

An analysis method of tetracyclines far fish and shellfish products containing large amount of low molecular materials and pigments was established. The recovery of the established analysis method for four tetracycline samples was $72-100\%$ and higher than other methods reported. Especially, proposed sample treatment protocol was shown to be effective for the removal of low molecular materials and pigments that tend to interfere with accurate analysis. The detection limit of oxytetracycline (OTC) and tetracycline (TC) from the sample was 0.02 ppm, and the detection limit of chlortetracycline (CTC) and doxycycline (DC) from the sample was 0.1ppm, To examine the efficiency of the established method and identify tetracycline usage in fish farms, tetracycline group antibiotics in the flounder being cultured was monitored. The improved method can be used for fish and shellfish products effectively and all surveyed fish farms have used tetracycline all the year round. The proposed method was adopted as official method for fishery products by Korean Food and Drug Administration in 2003 and it is being used by regulatory authority as National Fishery Products Quality Inspection Service.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.38 no.6
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• pp.379-384
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• 2005

A high-performance liquid chromatography assay method for oxolinic acid in fish products was developed, evaluated and validated through the monitoring of oxolinic acid based on farming and distribution. The recovery rate of the developed method was $102.3-106.7\%$ as compared to conventional methods. The stock solution was stable for 3 weeks under refrigerated condition at $4^{\circ}C$ The performance limit was evaluated as 0.01ppm of oxolinic acid in fish muscle. 478 fish samples such as olive flounder, genuine porgy, common sea bass and black rock fish collected from fish farms in the coastal area from September 2001 to October 2004 were analyzed to evaluate overall efficiency of the modified method and to monitor the actual condition of oxolinic acid usage in fish farm. According to the monitoring results, the modified method was suitable for analysis of oxolinic acid in fish muscle and oxolinic acid might be used in a small portion of fish farms. The suggested analysis method of oxolinic acid was registered in the Korean Official Methods of Food Analysis and is being utilized for fishery products by the Korea Food and Drug Adminstration and the National Fisheries Products Quality Inspection Service.