• Journal of Aquaculture
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• v.13 no.4
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• pp.317-323
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• 2000

Experimental cohorts of Mugil cephalus were divided into 5 groups : seawater~normal feed (SWN), acclimation to freshwater~normal feed (GFWN), acclimation to freshwater~salt feed (Gf\iVS), freshwater. normal feed (FWN) and freshwater-salt feed (f\iVS). Growth was faster in the SWN, Gf\iVS, and GFWN groups than in the f\iVS and FWN groups. Condition factor did not differ among the groups. Survival (92 %) of the juveniles was the highest in the Gf\iVS group; however, the others showed no significant difference. Moisture of FWN group was significantly higher than that of SWN group (P < 0.05). Potassium concentration was significantly higher in the SWN group than that of others (P < 0.05). It was highest (30 mmolfl) among the cohort of SWN.

• Ocean and Polar Research
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• v.26 no.3
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• pp.433-438
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• 2004

Stress response to the seawater acclimation in coho salmon (Oncorhynchus kisutch) smolt was investigated. Salt concentration of rearing water was gradually increased for 3 days from freshwater to seawater (30 ppt salt level). The changes of serum concentrations of cortisol as a primary stress indicator, and as secondary indicators, glucose (GLC), lactate (LAC), triglyce.ide (TG), cholesterol (CHOL), sodium ion $(Na^+)$, chloride ion $(Cl^-)$ and enzyme activities (alanine aminotransferase, ALT: aspartate aminotrasferase, AST; lactate dehydrogenase, LDH) were quantified during the acclimation experiment. Among them, cortisol, LAC, TG, CHOL, ALT, AST concentrations showed rapid increase at the first exposure to the 10ppt salt level (day 1), and began to decrease to the constant values after day 2 of adaptation at 20ppt salt level. However, LDH concentration tended to decrease during the whole experimental period. $Na^+\;and\;Cl^-$ showed slight decrease at day 1, and increased to a little bit higher values after day 2 rather than those in freshwater. All the fishes started on taking a food after day 4 of seawater adaptation. From these results, to reduce osmotic shock inducible stress to fish in seawater acclimation, gradual increase of salt levels is recommended.

• Proceedings of the Zoological Society Korea Conference
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• 1997.10b
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• pp.216.2-216
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• 1997

No Abstract, See Full Text

• Proceedings of the Korean Aquaculture Society Conference
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• 2006.05a
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• pp.359-360
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• 2006

• Korean Journal of Fisheries and Aquatic Sciences
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• v.44 no.3
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• pp.225-231
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• 2011

Prolactin (PRL) plays an important role in freshwater (FW) osmoregulation by preventing the loss of ions and the uptake of water in fish. Growth hormone (GH) promotes acclimation to seawater (SW) in several teleosts. We acclimated rainbow trout Oncorhynchus mykiss weighting $68.2{\pm}16.6$, $138.3{\pm}24$, and $287.5{\pm}42.1$ g in separate experiments to SW under slow-acclimation (SSW) or acute-acclimation (ASW) conditions, and then examined the PRL and GH mRNA levels using the real-time quantitative polymerase chain reaction. The PRL mRNA levels in all three experimental groups decreased significantly with both the SSW and ASW treatments, as compared to a control group kept in FW for 30 days. The GH mRNA levels increased with ASW in the largest fish, whereas the levels in the other groups did not change significantly. The mortality rate of the largest fish was lower than for the other groups, whereas the growth rate among the three experimental groups did not differ significantly. The growth rate of the ASW group was highest for the smallest fish. These results suggest that SW acclimation is associated with the gene expression levels of PRL and GH in relatively large rainbow trout. In addition, the fish mortality and growth rate on FW-SW transfer seem to be related to body weight, and the SW acclimation method may be applied to the hatcheries industry.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.37 no.1
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• pp.7-12
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• 2004

This study investigated the possibility of salinity acclimation of freshwater rotifers (Brachionus calyciflorus) as live food for sweetfish (Plecoglossus altivelis) larvae, and also examined the optimal salinity for the growth of sweetfish. Freshwater rotifers cultured in 0 and 4 PSU and seawater rotifers (B. rotundiformis) cultured in 33 PSU were supplied to the larvae with four kinds of enrichment material (condensed freshwater Chlorella, $\omega-yeast,$ baker's yeast, Super Selco) and larval growth at 4 PSU was examined. Growth of the freshwater rotifers positively increased from 0 PSU to 6 PSU, but decreased when over 8 PSU was reached. Growth and survival of the sweet fish larvae reared in 0 PSU were significantly lower than those reared in either 4 PSU or 33 PSU. This indicated that the freshwater rotifers (B. calyciflorus) could be used as live food for sweetfish larvae reared in 4 PSU. The body weight of sweetfish larvae fed on freshwater rotifers enriched with Super Selco was the highest at 0.163 mg, but there was no significant difference in survival and body length of the fish fed with the other enrichment materials. The content of n-3 HUFA of the sweetfish larvae fed on the freshwater rotifers enriched with Super Selco and the condensed freshwater Chlorella was higher than that enriched with $\omega-yeast$ and baker's yeast. These results indicated that B. calyciflorus cultured with the condensed freshwater Chlorella could be used for the sweetfish larvae without enrichment, and the most efficient enrichment material for B. calyciflorus is Super Selco.

• Journal of Fisheries and Marine Sciences Education
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• v.24 no.3
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• pp.387-394
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• 2012

Fertilization rates were over 90% when sperm from black porgy Acanthopagrus schlegelii acclimated and raised in freshwater and black porgy raised in seawater were fertilized with eggs from female black porgy raised in seawater, although cryopreserved sperm were significantly lower in fertilization rates than non-cryopreserved sperm. From the observations of embryos development at different salinities (0, 10, 20 and 32 psu) within 3 hours upon fertilization (16 cell stage), all were dead at 0 psu. However, the development process and speed at 10 and 20 psu were the same as at 32 psu. But, many developing embryos were egg envelope injury at low-salinities of 10 and 20 psu unlike at 32 psu. This is attributable to osmotic shock. Hatching rate of embryos at 32 psu was 60% or so, whereas low as 5% or less were successfully hatched at 10 and 20 psu, implying that osmotic shock could be responsible for the failure of embryo development.

• Journal of Microbiology and Biotechnology
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• v.31 no.2
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• pp.240-249
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• 2021

Phenotypic plasticity is a rapid response mechanism that enables organisms to acclimate and survive in changing environments. The Chinese mitten crab (Eriocheir sinensis) survives and thrives in different and even introduced habitats, thereby indicating its high phenotypic plasticity. However, the underpinnings of the high plasticity of E. sinensis have not been comprehensively investigated. In this study, we conducted an integrated gut microbiome and muscle metabolome analysis on E. sinensis collected from three different environments, namely, an artificial pond, Yangcheng Lake, and Yangtze River, to uncover the mechanism of its high phenotypic plasticity. Our study presents three divergent gut microbiotas and muscle metabolic profiles that corresponded to the three environments. The composition and diversity of the core gut microbiota (Proteobacteria, Bacteroidetes, Tenericutes, and Firmicutes) varied among the different environments while the metabolites associated with amino acids, fatty acids, and terpene compounds displayed significantly different concentration levels. The results revealed that the gut microbiome community and muscle metabolome were significantly affected by the habitat environments. Our findings indicate the high phenotypic plasticity in terms of gut microbiome and muscle metabolome of E. sinensis when it faces environmental changes, which would also facilitate its acclimation and adaptation to diverse and even introduced environments.

• Development and Reproduction
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• v.13 no.4
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• pp.313-320
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• 2009

The aim of this study was to test if 3,5,3'-triiodothyronine (T3) are involved in the osmoregulatory actions in euryhaline starry flounder Platichthys stellatus. We investigated osmoregulatory parameters ($Na^+,\;Cl^-$ and osmolality), blood cortisol and glucose in starry flounder acclimated to seawater (SW, 33 psu) and that were transferred and allowed to acclimate to freshwater (FW, 0 psu). Fish in SW were injected with T3 (5, 10, and $15{\mu}g$/g body weight) or vehicle (0.9% NaCl), and then transferred to FW. They were sampled 3 days after the transfer. With T3 at $10{\mu}g$/g, levels of plasma $Na^+$ and $Cl^-$ were significantly higher than in sham (only saline) and control fish (without hormone and saline). Osmolality was significantly higher after injection with T3 at 10 and $15{\mu}g$/g than in the control. However, T3 at $5{\mu}g$/g had no effect on hyper-osmoregulation. In this study, all dose of T3 induced a significant increases in plasma cortisol without glucose. These results suggest a positive hyper-osmoregulatory role of T3 in starry flounder to hypoosmotic environment, maybe a positive interaction of T3 with cortisol for maintenance of hyper-osmoregulatory ability.

• Journal of Aquaculture
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• v.22 no.1
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• pp.28-33
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• 2009

Physiological responses (hematological factors, cortisol, glucose, osmolality, $Na^+$, $K^+$ and $Cl^-$) in starry flounder Platichthys stellatus were investigated during freshwater acclimation in the conditions of different speeds in salinity change with acute-decrease (AD) or stepwise-decrease (SD I and II). In AD of acute-decrease salinity, hematocrit (Ht), red blood cell (RBC) and hemoglobin (Hb) were rapidly increased more than SD I of stepwise-decrease salinity. But in case of SD II, Ht, RBC and Hb were no significant difference from beginning to end of this experiments. In AD, cortisol level significantly increased from $2.1{\pm}1.0{\mu}g/mL$ at the beginning to $13.7{\pm}0.2{\mu}g/mL$ at 6 hours and recovered to the basal levels ($3.1{\mu}g/mL$) at 10 days. In SD I, cortisol level was significantly increased from $2.1{\pm}1.0{\mu}g/mL$ at the beginning to $13.6{\pm}0.6{\mu}g/mL$ at 6 hours and recovered to the basal levels ($3.1{\pm}0.4{\mu}g/mL$) at 10 days. In SD II, cortisol level was a little increased from $2.1{\pm}1.0{\mu}g/mL$ at the beginning to $10.5{\pm}2.5$, $10.8{\pm}5.6{\mu}g/mL$ at 6, 12 hours and recovered to the basal level at 48 hours. Glucose level of AD, SD I, II were no significant difference from beginning to end of this experiments. Osmolality was $286.8{\pm}3.3\;mOsm/kg$ at the beginning. In SD II of stepwise-decrease, osmolality was no significant difference during rearing in freshwater (FW). But AD of stepwise-decrease and SD I of stepwise-decrease, osmolality was a little decreased end of this experiments. In AD of acute-decrease, only $Cl^-$ level was showed no significant difference from beginning to end of experiment and $Na^+$, $K^+$ levels were decreased. In case of SD I, $Cl^-$ level was showed no significant difference from beginning to end of experiment and $Na^+$, $K^+$ levels were decreased.