• Journal of fish pathology
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• v.24 no.3
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• pp.189-195
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• 2011

Starry flounder, which are recently increasingly cultured in Korea, are known to highly vulnerable to Streptococcus parauberis infection. Five groups of starry flounder (n=30 for each group) were vaccinated with S. parauberis formalin-killed whole cells by intraperitoneal injection at a final concentration of 0, 0.01, 0.1, 1 and 10 mg $fish^{-1}$. Specific antibody production of 1 and 10 mg $fish^{-1}$ administered groups significantly increased at four weeks post immunization. All vaccinated groups showed higher survival rates than a control group when five groups of fish were challenged with S. parauberis at a dose of $1.14{\times}10^4$ cfu $fish^{-1}$ and $1.14{\times}10^2$ cfu $fish^{-1}$, respectively. In particular, 0.1 or higher concentrations of formalin killed bacterial cells are able to confer the fish high protection against S. parauberis infection.

• Fisheries and Aquatic Sciences
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• v.18 no.2
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• pp.173-181
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• 2015

We identified the $Na^+-K^+-2Cl^-$ cotransporter 2 (NKCC2) cDNA isoform from starry flounder, Platichthys stellate. The NKCC2 cDNA encoded a polypeptide of 1,043 amino acids representing 12 putative transmembrane domains based on the bioinformatic topology prediction. In addition, starry flounder NKCC2 possessed highly conserved residues within transmembrane domain 4, known as an essential site for its function. End-point reverse transcription-polymerase chain reaction analysis revealed that the NKCC2 transcript was moderately expressed only in the anterior and posterior intestines and the rectum. The NKCC2 mRNA level in the rectum, but not in other segments, was significantly induced 3 days post Streptococcus parauberis challenge, indicating that excess salt may be transported into the rectum. Taken together, our data indicate that an S. parauberis infection could tip the intestinal fluid balance in favor of fluid accumulation, indicating that bacterial pathogens can interfere with intestinal osmotic balance and normal mucosal immune homeostasis.

• Fisheries and Aquatic Sciences
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• v.22 no.5
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• pp.9.1-9.7
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• 2019

The study investigated the changes in growth performance, hematological parameters, plasma components, and stress indicators of juvenile starry flounder, Platichthys stellatus, depending on varying exposure to hexavalent chromium. P. stellatus was exposed to waterborne chromium at 0, 50, 100, 200, and 400 ppb for 4 weeks. The result showed that Cr exposure resulted in decreased daily length gain (DLG), daily weight gain (DWG), condition factor (CF), and hepatosomatic index (HIS) in P. stellatus. In terms of hematological parameters, red blood cell (RBC) count, hematocrit (Ht), and hemoglobin (Hb) significantly decreased at 400 ppb after 2 weeks. In terms of plasma components, inorganic analysis was unchanged and cholesterol, an organic component, considerably increased at 400 ppb after 4 weeks. Plasma enzyme components including glutamic oxalate transaminase (GOT) and glutamic pyruvate transaminase (GPT) were significantly increased. Stress indicators such as cortisol and glucose were notably increased over 100 ppb after 4 weeks with increasing chromium concentration. The results indicate that exposure to waterborne Cr induced toxic effects on growth, hematological parameters, plasma components, and stress indicators.

• Fisheries and Aquatic Sciences
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• v.22 no.1
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• pp.3.1-3.8
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• 2019

The purpose of this study is to investigate the changes in growth, hematological parameters, and plasma components of juvenile starry flounder, Platichthys stellatus, following exposure to varying arsenic concentrations present at different water temperatures. P. stellatus (total length, $15.9{\pm}0.4cm$; body weight, $62.2{\pm}4.2g$) were exposed for 4 weeks to waterborne arsenic (sodium arsenite, As) at 0, 150, 300, and $600{\mu}g/L$ at temperatures of $12^{\circ}C$ and $18^{\circ}C$. Toxic effects of As exposure on P. stellatus were higher at the higher temperature and the growth and hematological parameters measured decreased with increasing arsenic concentration, while the concentration of plasma components measured increased. This indicates that waterborne As exposure and water temperature can cause toxic effects on growth, hematological parameters, and plasma components in Platichthys stellatus.

• Journal of fish pathology
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• v.26 no.2
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• pp.77-88
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• 2013

Starry flounder, Platichthys stellatus (body length $4.4{\pm}0.51cm$) that became sick during an outbreak of disease at mariculture facilities at Ulsan, Korea in August of 2012, were examined to identify the cause of the disease. Diseased fish didn't show a unique sign, but the oxidase-positive and gram negative rod was isolated from moribund fish. The bacterium was revealed as Photobacterium damselae subsp. piscicida by biochemical analysis and sequence analysis of the 16S rRNA and capsular polysaccharide (CPS) genes. The isolates (AD5) was carrying susceptible to ofloxacin and gentamycin and showed high growth value at $18^{\circ}C$ and $25^{\circ}C$ compared to four other P. damsela strains.

• Development and Reproduction
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• v.17 no.4
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• pp.421-426
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• 2013

In this study, oocyte steroidogenesis are investigated in relation to oocyte development in the starry flounder, Platichthys stellatus, a marine multiple spawner. Vitellogenic (0.52 and 0.55 mm oocyte diameter) and mature oocytes (0.63, 0.66 and 0.71 mm oocyte diameter) were incubated in vitro in the presence of $[^3H]17{\alpha}$-hydroxyprogesterone ($[^3H]17{\alpha}$-OHP) as a precursor. Steroid metabolites were extracted from the incubated media and oocytes, the extracts were separated and identified by thin-layer chromatography (TLC), high performance liquid chromatography (HPLC) and gas chromatographymass spectrometry (GC-MS). The major metabolites produced from $[^3H]17{\alpha}$-OHP were androgens [androstenedione ($A_4$) and testosterone (T)] and estrogens [$17{\beta}$-estradiol ($E_2$) and estrone ($E_1$)] and progestins [$17{\alpha},20{\alpha}$-dihydroxy-4-pregnen-3-one ($17{\alpha}20{\alpha}P$) and $17{\alpha},20{\beta}$-dihydroxy-4-pregnen-3-one ($17{\alpha}20{\beta}P$)] in vitellogenic and mature oocytes. The results from this study suggest the potential roles of $E_1$ in the oocytes with diameter 0.52-0.71 mm, $17{\alpha}20{\alpha}P$ and $17{\alpha}20{\beta}P$ at the oocytes of 0.63, 0.66 and 0.71 mm.

• Fisheries and Aquatic Sciences
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• v.15 no.2
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• pp.117-123
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• 2012

The starry flounder Platichthys stellatus, like all flatfish, exhibits conspicuous lateral asymmetry in numerous traits, most obvious of which is the migration of one eye to the other side of the head during metamorphosis. Additional changes related to eye migration include asymmetrical pigmentation, and a behavioral shift from larvae that exhibit upright, open-water swimming to juveniles and adults that lie on the ocean floor, eye side up. However, the morphology of these juveniles has been quite plastic in recent years, a phenomenon which is thought to be related to a diverse suite of semi-intensive and intensive larviculture methods. The cause of morphological abnormalities in the farmed flatfish is poorly understood. In the present study, we observe the features of morphological specificity and abnormality of immature fish (mean total length 23 cm) and survey the occurrence frequency of the specificity and abnormality of juvenile (mean total length 6.70 cm) in artificial culture facility. We find 2 types of abnormality (e.g., albino in ocular side and hypermelanosis in blind side) and 1 type of specificity (e.g., lateral polymorphism). These considerably differ from normal individuals (has sinistral eye and pigmented on only one side) by several characteristics (dextral eye, ocular side albinism, blind side hypermelanosis). The incidences of albinism, hypermelanosis, and body reversal are $10.1{\pm}2.56%$, $91.7{\pm}1.7%$, and $13.1{\pm}1.1%$, respectively. These suggest that these morphometric and morphological differences occur more in artificial environment during and just after metamorphosis.

• Journal of Aquaculture
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• v.20 no.4
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• pp.212-218
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• 2007

Reproductive biology (sexual maturity and reproductive cycle) of starry flounder Platichthys stellatus were examined by histological methods. From March 2004 to February 2005, 144 females and males were sampled. Gonadosomatic index (GSI) of female and male were peaked in May and February, respectively. Monthly changes of hepatosomotic index (HSI) showed a negative correlationwith those of the GSI. Changes of condition factor (CF) in female were correlated with gonad maturation, while that of male were no difference all the year round. Based on monthly GSI and gonadal development the reproductive cycle of starry flounder could be divided into four stages: growing stage (September to November), maturation stage (September to February), ripe and spent stage (March to May), and recovery and resting stage (June to August). Biological minimum size of female was 1,074 g. The relationship between fecundity (F) and body weight (BW) of the fish was expressed as $F\;=\;455.86BW^{1.2006}$.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.40 no.6
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• pp.374-379
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• 2007

Two experiments were designed to examine short-term effects of human chorionic gonadotropin (hCG), and long-term effects of gonadotropin-releasing hormone agonist (GnRHa), $17{\alpha}-hydroxyprogesterone$ (17P), and $17{\alpha},20{\beta}-dihydroxy-4-pregnen-3-one\;(17,20{\beta}P)$, alone or in combination, on milt production of the starry flounder Platichthys stellatus. In the first experiment, fish were injected with either 200 IU hCG/kg body weight or the same volume of marine fish Ringer's solution (MFRS). In the second experiment, each fish was implanted with a blank cholesterol pellet (control), $200\;{\mu}g$ GnRHa, $500\;{\mu}g$ 17P, or $100\;{\mu}g\;17,20{\beta}P/kg$ body weight alone or in combination. In the first experiment, hCG injection resulted in an increase in the expressible milt volume and a decrease in the spermatocrit (Sct). After pellet implantation in the second experiment, the milt volume was increased in males treated with GnRHa, GnRHa+17P, or $GnRHa+17,20{\beta}P$. On day 7 after hormone pellet implantation, the milt volume began to increase, and on day 14, the milt volume in the $GnRHa+500\;{\mu}g$ 17P group was significantly higher than that in the control group. Compared with the control group, the hormone pellet-treated groups had a significant reduction in the mean Sct and sperm concentration (Sc) at day 7 after pellet implantation, while there were no differences in total sperm number. The results suggest that increases in milt volume are generally associated with decreases in Sct and SC, suggesting that the main mechanism for the increase in milt volume was milt hydration.

• Journal of Aquaculture
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• v.19 no.1
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• pp.47-51
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• 2006

Experiments were performed to find out the physico-chemical properties of milt and sperm motility in various storage conditions using starry flounder (Platichthys stellatus). The average sperm concentration and spermatocrit in stripped milt were $6.00{\pm}0.98{\times}10^8/mL\;and\;72{\pm}5$, respectively. The osmolality and pH were $337{\pm}9mmol/kg$ and $7.7{\pm}0.1$, respectively. The sperm of starry flounder was preserved with artificial seminal plasma (ASP), Stein's solution (SS) and marine fish Ringer's solution (MFRS) at $0^{\circ}C,\;2^{\circ}C,\;and\;4^{\circ}C$. The most effective condition for cold storage was SS at $0^{\circ}C$, and the preserved sperm remained motile for 30 days.