• Korean Journal of Fisheries and Aquatic Sciences
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• v.47 no.4
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• pp.399-405
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• 2014

We investigated the effects of feeding rate on the growth performance, blood components, and histology of growing olive flounder Paralichthys olivaceus. Optimum feeding rate (initial fish mean weight : $316.7{\pm}6.18g$) was determined under the optimum water temperature. Two replicated groups of fish were fed a commercial diet at rates of 0%, 0.4%, 0.6%, and 0.8% of body weight (BW) per day, and to satiation. Feeding trial was conducted using a flow-through system with 10 1.2-metric ton aquaria receiving filtered seawater at $21-24^{\circ}C$ for 3 weeks. Weight gain (WG) and specific growth rate (SGR) were significantly higher in fish fed to satiation (1.0% BW/day) than in those in other treatments. These parameters were negative and significantly lower in the starved fish than in fish fed the experimental diet at all feeding rates. There were no significant differences in WG and SGR among fish fed at 0.4%, 0.6%, and 0.8% BW/day. Hematocrit and hemoglobin in fish fed to satiation were significantly lower than those in other treatments. Histological changes of fish fed at 0.6% BW/day indicated that this group was in the best condition; differences were not found in tissues of fish fed at 0%, 0.6% and 1.0% BW/day. Broken-line regression analysis of weight gain showed that the optimum feeding rate of olive flounder weighing 317 g was 0.99% BW per day at the optimum water temperature.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.47 no.5
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• pp.582-587
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• 2014

We investigated the effects of feeding rate on the growth, blood components, and histology of sub-adult olive flounder Paralichthys olivaceus. Optimum feeding rate (initial fish mean weight : $384.2{\pm}5.91g$) was determined under the optimum water temperature. Two replicated groups of fish were fed a commercial diet at rates of 0%, 0.3%, 0.5%, and 0.7% body weight (BW) per day, and to satiation. The feeding trial was conducted using a flow-through system with ten 1.2-metric ton aquaria receiving filtered seawater at $20-24.5^{\circ}C$ for 3 weeks. After the feeding trial, the weight gain (WG) and specific growth rate (SGR) were significantly higher in fish fed at 0.7% BW/day and those fed to satiation (0.9% BW/day) than in fish fed at other feeding rates or in the unfed fish. These parameters were negative and significantly lower in the unfed fish than in those fed the experimental diet at all feeding rates. There were no significant differences in WG and SGR among fish fed at 0.3 and 0.5% BW/day and among those fed at 0.7% BW/day and to satiation. The histological changes in the hepatopancreas, kidney, and anterior intestine of fish fed at 0, 0.5, and 0.9 % BW/day did not differ much. Broken-line regression analysis of weight gain showed that the optimum feeding rate of olive flounder weighing 384 g was 0.74% BW per day at the optimum water temperatures.

• Journal of Environmental Health Sciences
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• v.43 no.3
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• pp.194-201
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• 2017

Objectives: Zinc oxide nanoparticles (ZnO NPs) are widely used in various commercial products, but they are exposed to the environment and can induce toxicity. In this study, we investigated the environmental fate and bioaccumulation of ZnO NPs in a microcosm. Methods: The microcosm was composed of water, soil (Lufa Soil 2.2) and organisms (Oryzias latipes, Neocaridina denticulata, Semisulcospira libertina). Point five and 5 mg/L of ZnO NPs were exposed in the microcosm for 14 days. Total Zn concentrations were measured using an Inductively Coupled Plasma Mass Spectrometer (ICP-MS) and intracellular NPs were observed using Transmission Electron Microscopy (TEM). Results: In the initial stages of exposure, the Zn concentrations in water increased in all exposure groups and then decreased, while the Zn concentration in soil increased after three hours for the 5 mg/L solution. Zn concentrations also showed increasing trends in N. denticulata and S. libertina at 0.5 and 5 mg/L, and in O. latipes at 5 mg/L. Accumulation of NPs was found in the livers of O. latipes and hepatopancreas of N. denticulata and S. libertina. Conclusions: In the early stages of exposure, ZnO NPs remained in the water, and then were transported to the soil and test species. Unlike other species, total Zn concentrations in N. denticulata and S. libertina increased for both 0.5 mg/L and 5 mg/L. Therefore, ZnO NPs were more easily accumulated in zoobenthos than in fish.

• Journal of Aquaculture
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• v.9 no.4
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• pp.445-452
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• 1996

Endogeneous activities of ${\beta}-galactosidase$-like enzyme in various tissues from several finfishes and shellfishes were examined by histochemical analysis based on X-gal staining and by fluorimetric measurement using 4-methylumbelliferyl-${\beta}$-D-galactoside (4-MUG). Species used in this study were 3 freshwater fishes, mud loach (Misgurnus mizolepis), common carp (Cyprinus carpio) and tilapia (Oreochromis niloticus) ; 3 marine fishes, olive flounder (Paralichthys olivaceus), stone flounder (Kareius bicoloratus) and marbled sole (Limanda yokohamae) ; and 4 shellfishes, abalone (Haliotis discus hannai), Pacific oyster (Crassoskra gigas), pearl oyster (Pinctada fucata martensii) and ark shell (Anadara broughtonii). The activities of ${\beta}-galactosidase$-like enzyme in all finfishes examined were significantly different among species, with the wide variations between tissues in a species. In general, the tissues such as kidney, intestine and liver were ones which showed the significantly higher values in 4-MUG fluorimetry and deeper staining patterns in X-gal analysis compared to other tissues. On the other hand, serum and muscle revealed the significantly lower activities than others did, regardless of species. Shellfishes were also found to have endogenous activities of ${\beta}-galactosidase$-like enzyme which were significantly varied depending on both species and organs in a species. Hepatopancreas from all shellfishes examined showed the deepest pattern in X-gal staining and also the highest value in 4-MUG analysis, while activities of ${\beta}-galactosidase$-like enzyme in adductor muscles and mantle muscles from all shellfish species in this study except Pacific oyster were negligible : Pacific oyster had the significant activity of this enzyme in muscle tissues. Putative endogenous lacZ fragment was amplified from both finfishes and shellfishes by polymerase chain reaction (PCR). The molecular size of PCR products was about 510 bp, and there was no difference in size among species examined.

• Fisheries and Aquatic Sciences
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• v.20 no.4
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• pp.6.1-6.8
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• 2017

The objective of this research was to study the effect of astaxanthin (AST) on growth performance and antioxidant capacity in golden pompano (Trachinotus ovatus) both in vivo and in vitro. In the in vivo study, two diets were formulated with or without astaxanthin supplementation (D1 and D2; 0 and 200 mg/kg) to feed fish for 6 weeks. In the in vitro study, cells from hepatopancreas of golden pompano were isolated and four treatments with or without astaxanthin and $H_2O_2$ supplementation were applied (control group: without both astaxanthin and $H_2O_2$ treated; $H_2O_2$ group: just with $H_2O_2$ treated; $H_2O_2$ + AST group: with both astaxanthin and $H_2O_2$treated; AST group: just with AST treated). Results of the in vivo study showed that weight gain (WG) and special growth rate (SGR) significantly increased with astaxanthin supplemented (P < 0.05). Feed conversion ratio (FCR) of fish fed D2 diet was significantly lower than that of fish fed D1 diet (P < 0.05). Hepatic total antioxidant capacity (T-AOC) and the reduced glutathione (GSH) of golden pompano fed D2 diet were significant higher than those of fish fed D1 diet (P < 0.05). Superoxide dismutase (SOD) was significantly declined as astaxanthin was supplemented (P < 0.05). Results of the in vitro study showed that the cell viability of $H_2O_2$ group was 52.37% compared to the control group, and it was significantly elevated to 84.18% by astaxanthin supplementation ($H_2O_2$ + AST group) (P < 0.05). The total antioxidant capacity (T-AOC) and the reduced glutathione (GSH) of cell were significant decreased by oxidative stress from $H_2O_2$ (P < 0.05), but it could be raised by astaxanthin supplementation ($H_2O_2$ vs $H_2O_2$ + AST), and the malondialdehyde (MDA) was significant higher in $H_2O_2$ group (P < 0.05) and astaxanthin supplementation could alleviate the cells from lipid peroxidation injury. In conclusion, dietary astaxanthin supplementation can improve the growth performance of golden pompano. Moreover, astaxanthin can improve the golden pompano hepatic antioxidant capacity both in vivo and in vitro study by eliminating the reactive oxygen species.

• Journal of Marine Bioscience and Biotechnology
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• v.2 no.1
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• pp.34-39
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• 2007

Penaeidins are members of a special family of antimicrobial peptides existing in several species of shrimp and play a crucial role in the immunological defense of shrimp. In this study, we isolated and characterized one EST clone (penaeidin) from cDNA library of fleshy prawn Fenneropenaeus chinensis hemocytes. Amino acids sequence comparison and phylogenetic analysis with other known penaeidins revealed that our clone was completely identical to F. chinensis Penaeidin 3-2 (Accession no. ABC33920), which composed of 71 amino acids with a putative signal peptide (1-19) and a cysteine-rich domain (C-terminal part). The expression and distribution of Penaeidin 3-2 transcripts in shrimp were detected in hemocytes, hepatopancreas, and muscles, and that Penaeidin 3-2 was constitutively expressed mainly in hemocytes. The artificial infection of white spot syndrome virus to F. chinensis resulted in Penaeidin 3-2 mRNA up-regulation in hemocytes, suggesting that the possible role of Penaeidin 3-2 in host defense system of F. chinensis.

• The Korean Journal of Malacology
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• v.25 no.2
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• pp.145-151
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• 2009

The ultrastructural changes in germ cells during oogenesis of the melania snail, Semisulcospira libertina libertina have been investigated by light and electron microscopy. The ovary is located on the surface of the hepatopancreas in the spiral posterior region. The ovary exhibited greenish color in the gonadal mature season. The ovary was composed of a number of oogenic follicles. Oogenesis was divided into five stages with histological features: (1) oogonia, (2) previtellogenic, (3) initial vitellogenic, (4) active vitellogenic, and (5) mature stages. Oogonia were oval in shape, $4-6\;{\mu}m$ in diameter, and had a large nucleus. Previtellogenic oocytes were about $20\;{\mu}m$ in diameter and the cytoplasm reacted with hematoxylin in H-E satin. Initial vitellogenic stage, oocytes were $60-80\;{\mu}m$ in diameter, and small yolk granules of low electron density are scattered in the cytoplasm. Oocytes in the initial vitellogenic stage were connected with ovarian follicle by egg stalk. Active vitellogenic oocyte were $100-120\;{\mu}m$ in diameter. Electron density, size and quantity of yolk granules that are distributed in the cytoplasm have increased from the previous stage. Result of TEM observations, the oocyte contains well-developed Golgi complex, endoplasmic reticula and tubular mitochondria in the cytoplasm. Cytoplasm of mature oocyte was filled with proteinaceous yolk globules of high electron density. In this stage, the length of microvilli in the egg envelope was approximately $1.1\;{\mu}m$.

• Korean Journal of Environmental Biology
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• v.31 no.3
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• pp.204-212
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• 2013

This study analyzed the occurrence of tunic softness, survival rate, metabolic rate and histopathologic changes arising from the effect of hypoxic environment in order to find the causes of occurrences of tunic softness, which manifests as the key phenomenon of mass mortality of Halocynthia roretzi. Regarding the survival of H. roretzi with reduction in dissolved oxygen, all the entities died on the 4th day of exposure to the dissolved oxygen concentration of $2mg\;L^{-1}$ while 50% mortality was observed on the 5th day of exposure to the dissolved oxygen concentration of $3mg\;L^{-1}$. Therefore the 5 days-$LC_{50}$ was found to be $3.55mg\;L^{-1}$ (1.86~$4.96mg\;L^{-1}$). However, occurrence of tunic softness was not observed during the period of exposure to low oxygen concentration. The oxygen consumption rate significantly decreases at the dissolved oxygen concentration of less than $5mg\;L^{-1}$ in comparison to the control group. Therefore, it is presumed that H. roretzi controls the respiration rate for prescribed period of time when exposed to hypoxic environment. Regarding the histopathologic changes in the gill, digestive gland and cyst of H. roretzi due to hypoxic environment, necrosis of epithelial layer, in filtration of blood cells, and condensation of nucleus that compose each of the organs were observed. Regarding morphological changes, the decrease in volume with shrinking of the tunic, discoloration of the internal organs and necrosis of gill and hepatopancreas were observed.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.22 no.5
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• pp.342-350
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• 1989

Maturity and spawning of Crangon affinis were studied based on the histological observation. The samples were monthly collected in Nakdong estuary from June, 1988 to May, 1989. The gonad lies on the dorsal side of the thorax. The cavity in which it lies is located below heart and above hepatopancreas. Anterior part of ovary is fused roundly, and the posterior part shows a pair of tubule-like structure. Testis is bilaterally symmetrical; the anterior part shows convoluted tubule, and the posterior part consists of a pair of tubule. Seminal vesicle is connected and opened to the base of the fifth pereiopod. Gametogenesis of ovum and spermatozoon is being repeated in short period without seasonality, and it is formed simultaneously in the whole parts of germinal epithelium. Diameter of a ripe oocyte is ca. $430{\mu}m$. Spermatozoa is oval with distinct nucleoplasm. Reproductive cycle is performed in ca. 40 days. Crangon affinis spawns all year round except November. Incubation period of brooded eggs took $12\~14$ days before hatching in the aquarium at $21^{\circ}C\~24^{\circ}C\;and\;33\%_{\circ}$.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.33 no.5
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• pp.403-407
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• 2000

Ultrastructure and function of testis somatic cells in freshwater prawns Macrobrachium nipponense were studied. The paired testes of the prawn were elongated, united at their anterior end, which lay between the dorsal surface of the hepatopancreas and the heart. Each testis consisted of a large number of seminiferous cords compactly held together by connective tissue. A seminiferous cord was composed of an outer layer of simple squamous epithelium, a basement membrane, the closely packed germ cells and sustentacular cells of the germinal ridge, and an inner layer of simple cuboidal epithelial cells. Leydig cell-like cells in an angular areas filling the space of the seminiferous cords were observed. The nuclei of leydig cell-like cells were characterized by a distinct nucleolus. The simple squamous epithelial layer was composed of flattened cells tying on a basement membrane. The nuclei of the flattened cells were often overlapped in a layer, and the cytoplasm of the cells was observed just near the nuclei. The sustentacular cells were complex in morphology. These cells had relatively small cell bodies from which long cytoplasmic extensions ramified reached the space of germ cells in the germinal ridge. The nuclei of sustentacular cells usually exhibited angular profiles and located most commonly at the periphery of the cords. Cells of simple cuboidal epithelium located between germinal ridge and lumen of seminiferous cord, and part of the cells were adjacent to basal lamina, The cuboidal epithelial cells contained numerous mitochondria, the well-developed rER, the well-developed Golgi complex, and irregularly shaped nuclei. Transition vesicles appeared on the cis side of the Golgi complex. The large vesicles on the trans side of the complex appeared to fuse to form a membrane-bound structure. A number of pits on the cell apex suggested exocytotic activity for secretion of the sperm supporting matrix.