• Korean Journal of Microbiology
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• v.49 no.1
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• pp.58-63
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• 2013

A taxonomic study was carried out to assess the phylogenetic characteristics of isolate JJM57 from marine red algae Laurencia sp. collected from intertidal zone in Jeju Island, South Korea. Comparative analysis of 16S rRNA gene sequence shows that this isolate belongs to the genus Oceanisphaera. It shows 98.02% and 97.7% sequence similarity with Oceanisphera litoralis DSM $15406^T$ and Oceanisphera donghaensis KCTC $12522^T$, respectively. Strain JJM57 is a Gram-negative, aerobic, moderately halophilic bacterium able to grow in different NaCl concentration ranges from 0.5 to 8.0% and at varying temperatures from 4 to $37^{\circ}C$. Sharing some of the physiological and biochemical properties with O. litoralis and O. donghaensis, JJM57 strain differs in the utilization of ethanol, proline, and alanine. The G+C contents of the strain JJM57 is 61.94 mol% and it is rich in $C_{16:1}$ ${\omega}7c$ and/or iso-$C_{15:0}$ 2-OH, $C_{16:0}$, and $C_{18:1}$ ${\omega}7c$ fatty acids. The DNA-DNA relatedness data separates the strain JJM57 from other species such as O. litoralis and O. donghaensis. On the basis of these polyphasic evidences, present study proposed that strain JJM57 (=KCTC 22371 =AM983543 =CCUG 60764) represents a novel bacterial species of Oceanisphaera.

• Journal of the Korean Society of Food Science and Nutrition
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• v.17 no.2
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• pp.125-135
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• 1988

In recent years, the presence of N-nitrosamine, which was produced by the interaction of nitrite and secondary amine, in the fermented foods has been the subject of considerable interest and controversy. In this experiment, the levels of N-nitrosamine such as N-nitrosodimethylamine(NDMA), N-nitrosodiethylamine(NDEA) and N-nitrosodipropylamine(NDPA) in the Korean ordinary soysauce, which were added with ascorbic acid, sorbic acid, and sodium benzoate in the making of it were analyzed by low resolution mass spectrometry, and then the changes of dimethylamine(DMA), nitrate and nitrite nitrogen during the fermentation of it were observed. The contents of DMA nitrogen increased during the fermentation of Korean ordinary soysauce, continuously, but those of DMA nitrogen in the soysauce which had been added with ascorbic acid were inhibited, considerably, until the fermentation of 70days. The levels of nitrate nitrogen during the fermentation of Korean ordinary soysauee decreased, while those of nitrite nitrogen increased. The soysauce which had been incoporated with ascorbic acid in the making of it showed low amounts of nitrite. The concentration of NDMA in the control sample were 2.7 and $8.5{\mu}g/kg$ after the fermentation of 30 and 60 days, respectively, those of NDMA increased during the fermentation of Korean ordinary soysauce, but NDEA and NDPA in all of the soysauce were not detected. The samples were treated with ascorbic acid, sorbic acid, and sodium benzoate in the making of Korean ordinary soysauce were turn out to be effective in preventing the formation of NDMA. Inhibitive actions from food additives as above were, respectively, $82.2{\sim}87.0%$(ascorbic acid), $25.9{\sim}65.4%$(sorbic acid) an $13.2{\sim}63.5%$ (sodium benzoate) in comparison with control sample during the fermentation of Korean ordinary soysauce. NDMA contents were detected below $1.5{\mu}g/kg$ in the soysauce, which food additives were mixed to the pure NaCI in the brewing of it. Free amino acids such as glutamic acid, proline, and histidine were proved to be inhibiting the formation of NDMA during the fermentation of Korean ordinary soysauce. This might be due to the reaction above amino acids and nitrite by Van Slyke reaction.

• Korean Journal of Ichthyology
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• v.1 no.1_2
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• pp.73-82
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• 1989

The development of eggs and larvae, and minute scale-like tubercles on the skin surface of the larval Acanthorthodeus asmussi from Korea were observed in the laboratory. The egg was nearly ovoid-shaped. The number of egg averaged 195 per an oviposition. The morphological character of larval development was relatively similar to those of Acheilognathus tabira tabira, A. tabira subsp. (a), A. yamatsutae, A. moriokae, A. cyanostigma and A. rhombeus. The larvae of this species had many scale-like tubercles ellipsoided in a diagonal cross section on the skin surface of the body. And also this species moved like incessant wiggly movement pattern as that of fly maggot duing the larval development. As regards the tubercles and larval movement pattern, the larvae of A. asmussi shared similar characters with those of Acheilognathus rhombeus, A. longipinnis and Pseudoperilampus typos. Hence A. asmussi may be closely related to these species. The latter three species are autumn-spawning bitterlings and the larval development always retard in a certain stage, while A. asmussi is a spring-summer spawning species and the larval development never retards. Judging from these facts, it should be considered that there are close relations in evolutionary trend between the two spawning species.

• Journal of fish pathology
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• v.6 no.2
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• pp.111-122
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• 1993

The mechanism by which $V_H$ region gene segments is selected in B lymphocyte is not known. Moreover, evidence for both random and nonrandom expression of $V_H$ genes in matured B cells has been presented previously. In this report, the technique of in situ hybridization allowed us to analyze expressed $V_H$ gene families in normal B lymphocyte at the single cell level. The analysis of normal B cells in this study eliminated any posssible bias resulting from transformation protocols used previously and minimized limitation associated with sampling size. Therefore, an accurate measure of the functional and expressed $V_H$ gene repertoire in B lymphocyte could be made. One of the most important controls for the optimization of in situ hybridization is to establish probe concentration and washing stringency due to the degree of nucleotide sequence similarlity between different families which in some cases can be as high as 70%. When the radioactive $C{\mu}$ and $V_{H}J558$ RNA probes are tested on LPS-stimulated adult spleen cells, $2{\sim}4{\times}106cpm$/slide shows low background and reasonable frequency of specific positive cells. For the washing condition. 40~50% formamide at $54^{\circ}C$ is found to be optimum for the $C{\mu}$. $V_{H}S107$ and $V_{H}J558$ probes. The analyzed results clearly demonstrate that the level of each different $V_H$ gene family expression is dependent upon the complexity or size of that family. These findings are also extended to the level of $V_H$ gene family expression in separated bone marrow B cells depend upon the various stage of differentiation and conclude no preferential utilization of specific $V_H$ gene family. Thus, the utilization of VH gene segments in B lymphocyte of adult BALB/c mice is random and is not regulated or changed during the differentiation of B cells.

• Journal of Aquaculture
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• v.13 no.3
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• pp.267-275
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• 2000

To evaluate the characteristics and efficiency of oxygen transfer rate of a polystyrene foam bead as media in a packed column aerator was tested. This media has more surface area and cheaper than other ordinary plastic media. The polystyrene foam media was a sphere-shaped bead with 2.5 mm in diameter and specific surface area was 1,350 $m^2$/$m^3$. Oxygen transfer rate and standard aeration efficiency were tested under different hydraulic loading rates, depths of the media and temperatures. Experiment 1 was performed using a small packed column aerator with 10 cm in diameter and 1 m in length. The aerator filled with 0, 4.5, 9.0 and 18.0 cm of the media was tested under hydraulic loading rates of 2.0, 4.0 and 5.6 $m^3$/$m^2$/min at temperatures of 20, 25 and 3$0^{\circ}C$, respectively. In this experiment, standard oxygen transfer rate (SOTR) increased with the hydraulic loading rate and depth of the media increased. The maximum SOTR was reached at 5.6 $m^3$/$m^2$/min of hydraulic loading rate with 9 cm in depth of the media. However, standard aeration efficiency (SAE) decreased with the hydraulic loading rate increased because electricity consumed by pump increased as hydraulic loading rate increased. The highest SAE was reached at hydraulic loading rate of 2.0 $m^3$/$m^2$/min with 9.0 cm in depth of the media. Therefore, the highest SOTR and SAE were achieved at 9.0 cm in depth of the media regardless of the hydraulic loading rate. The maximum SAE was about 1.8 kg $O_2$/kW-hr with the hydraulic loading .ate of $m^3$/$m^2$/min at temperature of 20 $^{\circ}C$.Experiment 2 was performed using a larger aerator, 20 cm in diameter with 2 m in height. The aerator filled with 0, 9, 18, 27 and 36 cm of the media was operated under hydraulic loading rate of 2.0, 4.0 and 5.6 $m^3$/$m^2$/min at temperature of 27 $^{\circ}C$. The SAE reached to the highest efficiency (1.9 kg $O_2$/kW-hr) at 2.0 $m^3$/$m^2$/min of hydraulic loading rate and 36 cm in depth of the media. According to the above results, the polystyrene foam bead as a media in a packed column aerator was effective to increase oxygen transfer rate.

• Journal of Aquaculture
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• v.19 no.1
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• pp.25-32
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• 2006

An experiment was carried out to investigate changing of water quality during the seed production of dark-banded rockfish Sebastes inermis in large scale tanks. Ten broodstock of dark-banded rockfish were held in three circular tanks (diameter 6.5 m; depth 2 m; water volume 50 ton) each (stocking density $0.061kg/m^3$). During the experiment the temperature ranged from 14.2 to $16.1^{\circ}C$. The fingerlings were 134 with rotifers only during 1 to 9 days after parturition, rotifers with Artemia nauplii during 10 to 20 days after parturition, Artemia nauplii only during 21 to 35 days after parturition, Artemia nauplii with commercial diet during 36 to 80 days after parturition and commercial diet only during 81 to 85 days after parturition. Water quality (dissolved oxygen, pH, $NH_4^+-N,\;NO_2^--N,\;NO_3^--N\;and\;PO_4^{3-}-P$) in rearing tanks measured every 5 days in long term monitoring investigation or every 2 hours in diurnal monitoring investigation. In 85 days after parturition, the body weight of fish grew up to 0.88 f and specific growth rate was 8.0%/day in body weight. In long term monitoring investigation, with the increase of the amount of supplied commercial diet, the concentration of dissolved oxygen (DO) and pH decreased, but the concentration of $NH_4^+-N\;(4.5\;to\;76.3{\mu}M),\;NO_2^--N\;(0.02\;to\;0.06{\mu}M),\;NO_3^--N\;(3.0\;to\;5.9{\mu}M)$, and $PO_4^{3-}-P\;(0.41\;to\;0.59{\mu}M)$ increased. In the diurnal monitoring investigation, the concentration of $NH_4^+-N$ showed great fluctuation and ranged from 3.0 to $9.1{\mu}M$ when fed rotifers, 16.3 to $45.8{\mu}M$ when fed Artemia nauplii and 36.5 to $120.1{\mu}M$ when fed commercial diet. After daily feeding with each of feed, the amount of dissolved inorganic nitrogen (DIN) and phosphorus (P) wastage were 7.0 g and 0.7 g when fed rotifers, 24.7 g and 0.7 g when fed Artemia nauplii and 140.9 g and 2.2 g when 134 commercial diet. The amount of DIN and phosphorous wastage during 134 commercial diet was significantly higher than that of fed rotifer and Artemia nauplii (P<0.05). Results will provide valuable information far water quality management and culture of dark-banded rockfish in commercial seed production systems.

• Journal of Aquaculture
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• v.19 no.4
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• pp.275-280
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• 2006

Effect of the various sources of dietary additives on growth, body composition and shell color of abalone Haliotis discus hannai was investigated for 16 weeks. Forty juvenile abalone averaging 13.5 g were randomly stocked into 21 of 50 L plastic rectangular containers each. Eight kinds of additives were prepared for this study: four commercially available microalgae [Haeatococcus (Hae), Isochrysis galbana (Iso), Shizochytrium (Sch) and Spirulina (Spi)], three crustacean meals [krill meal (KM), shrimp head meal (Shm) and red crab meal (Rcm)], and green tea by-product (Gre). In addition, dry sea tangle (Dst), Laminaria japonica, as a control, was prepared. Casein, dextrin and a mixture corn oil and fish oil was protein, carbohydrate and lipid sources, respectively, in the experimental diets. The 2% each additive was included into the experimental diets. The experimental diets were fed to abalone once a day at the ratio of $1.5{\sim}2.0%$ total biomass of abalone with a little leftover throughout the 16-week feeding trial. Survival of abalone was not significantly (P>0.05) affected by the experimental diets. However, weight gain of abalone fed the all experimental diets containing the various sources of additives was significantly (P<0.05) higher than that of abalone fed the Dst diet. Weight gain of abalone fed the Spi diet was highest and Shi, KM and Iso diets in order. Shell length and the ratio of soft body weight to body weight of abalone was not significantly (P>0.05) affected by the experimental diets. However, shell width of abalone fed the all experimental diets containing the various sources of additives was significantly (P<0.05) higher than that of abalone fed the Dst diet. The shell color of abalone fed the Spi diet was improved the most distinctively and similar to that of natural abalone. Therefore, it can be concluded that the experimental diets with the various sources of additives (microalgae and crustacean meals) was effective to improve growth of abalone and dietary inclusion of Spirulina was most effective to improve shell color of abalone.

• Journal of Aquaculture
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• v.19 no.4
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• pp.267-274
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• 2006

To understand the changes in plasma levels of sex steroids in the wild Japanese eel Anguilla japonica during artificially maturing process, eels received weekly intraperitoneal injections of a water-in-oil (W/O) type emulsion with Freund`s incomplete adjuvant containing salmon pituitary extract (SPE; 20 mg pituitary powder/fish) were examined. In the weekly Eel's Ringer-treated control wild eels, the body weight (BW) changes of fish decreased slowly during the experiment period. Plasma testosterone (T), $estradiol-17{\beta}\;(E_2)$ and $17a,20{\beta}-dihydroxyprogesterone$ (DHP) levels did not change significantly at the end of the experiment. In the weekly SPE-treated silver eels, however, rapid increase in BW changes occurred after 6 to 10 weeks, and the oocytes of all fish were observed to be in the migratory nucleus stage. Furthermore, significant increase in sex steroid hormones (T and $E_2$) levels occurred from 6 weeks. In the weekly SPE-treated yellow eels, the BW changes of fish increased slowly at 6 weeks and then increased. In these fish, the oocytes were at the tertiary yolk globule stage even at the end of the experiment. Plasma sex steroid hormones profiles revealed individual variability in SPE-treated yellow eels. Plasma T and $E_2$ levels significantly increased at 8 weeks and after 6 weeks, respectively, in SPE-treated yellow eels. In the weekly SPE-treated wild eels (silver and yellow eels), however, plasma DHP levels did not change significantly during the experiment period. In silver eel, final maturation could be induced by weekly administration of SPE using W/O type emulsion.

• Journal of Bio-Environment Control
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• v.27 no.1
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• pp.34-39
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• 2018

This research was conducted to estimate moisture content in cucurbitaceae seedlings, such as cucumber and watermelon, using hyperspectral imagery. Using a hyperspectral image acquisition system, the reflectance of leaf area of cucumber and watermelon seedlings was calculated after providing water stress. Then, moisture content in each seedling was measured by using a dry oven. Finally, using reflectance and moisture content, the moisture content estimation models were developed by PLSR analysis. After developing the estimation models, performance of the cucumber showed 0.73 of $R^2$, 1.45% of RMSE, and 1.58% of RE. Performance of the watermelon showed 0.66 of $R^2$, 1.06% of RMSE, and 1.14% of RE. The model performed slightly better after removing one sample from cucumber seedlings as outlier and unnecessary. Hence, the performance of new model for cucumber seedlings showed 0.79 of $R^2$, 1.10% of RMSE, and 1.20% of RE. The model performance combined with all samples showed 0.67 of $R^2$, 1.26% of RMSE, and 1.36% of RE. The model of cucumber showed better performance than the model of watermelon. This is because variables of cucumber are consisted of widely distributed variation, and it affected the performance. Further, accuracy and precision of the cucumber model were increased when an insignificant sample was eliminated from the dataset. Finally, it is considered that both models can be significantly used to estimate moisture content, as gradients of trend line are almost same and intersected. It is considered that the accuracy and precision of the estimating models possibly can be improved, if the models are constructed by using variables with widely distributed variation. The improved models will be utilized as the basis for developing low-priced sensors.

• Horticultural Science & Technology
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• v.28 no.4
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• pp.529-534
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• 2010

Occurrence of wilted symptom in watermelon plant ($Citrullus$ $lanatus$ L.) is known to be caused by physiological disorder. The symptom results in the loss of fruit production and thus the economical loss of watermelon growers. The incidence of symptom is often found from the middle of March to the end of May in the major watermelon crop production areas of Korea (i.e. Uiryeong, Gyeongnam (lat $37^{\circ}$56'64"N, long $126^{\circ}$99'97"E)). Despite of extensive information about the physiological disorder, little study has been conducted to understand a relationship between the wilted symptom and accompanying environment factors (e.g. temperature). This study aimed to investigate effects of environmental conditions amended by a forced-ventilation system on physiological characteristics of watermelon and incidence of the wilted symptom. Watermelon plants were grown from January to May, 2009 with either the forced-or natural-ventilation treatment in a greenhouse located in the Uiryeong. In the result, the forced-ventilation treatment decreased the air, leaf and root-zone temperature approximately $4.5^{\circ}C$, $5^{\circ}C$ and $3^{\circ}C$, respectively, compared to the natural-ventilation. The fruit growth rate was maximized twice during the entire growing period. The higher rate of fruit growth was observed under the natural-ventilation than the forced one. Maximization of the fruit growth rate (approximately 430 g per day) was first observed by 12 days after fruiting under the natural-ventilation treatment, while the second one (approximately 350 g per day) was observed by 24 days after fruiting. The wilted symptom started occurring by 22 days after fruiting under the natural-ventilation, whereas no incidence of the symptom was found under the forced-ventilation treatment. Interestingly, the forced-ventilation lowered the fruit growth rate (approximately 320 g per day) compared to the natural one. Maximization of the fruit growth rate under the forced-ventilation was found at 4 days later than that under the natural one. This result coincided with a slower plant growth under the forced-ventilation treatment. These results suggest that the forced-ventilation slows down extension growth of fruit and plant, which may be associated with lowering leaf temperature and saturation deficit. We suggest the hypothesis that the forced-ventilation may alleviate stress of the wilted symptom by avoiding extreme water evaporation from leaves due to high temperature and thus by reducing competition between leaves and fruits for water. More direct and detailed investigations are needed to confirm the effect of the forced ventilation.