• Korean Journal of Fisheries and Aquatic Sciences
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• v.43 no.5
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• pp.474-481
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• 2010

The sperm collection time, sex steroid hormones, and gonadal development of protandrous black porgy, Acanthopagrus schlegeli, acclimated in freshwater for more than 2 years were investigated to evaluate its reproductive capability. The gonadal development of black porgy reared in seawater and freshwater could each be classified into four successive stages. For black porgy reared in seawater (BSW) as the control, these were the growing (December to February), mature (February to March), spent (March to June), and degeneration and resting (July to December) stages; for black porgy reared in freshwater (BFW), these were the growing (November to January), mature (January to February), spent (February to May), degeneration and resting (June to November) stages. In both BSW and BFW, the plasma cortisol levels were the highest in March. The plasma testosterone (T) levels of BSW and BFW were the highest in March and February, respectively. The plasma estradiol-$17{\beta}$ ($E_2$) levels did not differ significantly between BSW and BFW. The 11-ketotestosterone (11-KT) levels in the plasma of BSW and BFW were the highest in April. Sperm was collectible from March to June in BSW and from February to May in BFW. The results indicated that the gonadal maturation of BFW was about 1 month faster than that of BSW.

• 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.

• The Korean Journal of Zoology
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• v.35 no.3
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• pp.263-270
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• 1992

Responses of immunoreactive atrial natriuretic peptide (ir-ANP) to environmental temperature were studied in the freshwater catfish, Silums usotus, acclimated at various temperatures for one week. According to increase in environmental temperature, plasma sodium and chloride concentrations, and osmolality were significantly increased, while hematocrit showed a marked decrease. When the catfishes frere acclimated at cold $(3^{\circ}C)$ or warm $(18^{\circ}C)$ temperatures, ir-ANP contents in the atrium and bulbus arteriosus were significantly lower than those at $9^{\circ}C.$ However, ventricular contents of ir-ANP urere not different among the three groups.Levels of plasma ir-ANP in the catfish increased in response to the increment of acclimated temperature. On the basis of these results, we suggest that the environmental temperature may modulate synthesis and secretion of ir-hUP in the fish. We also suggest that changes of plasma ir-ANP levels may be associated with the control of body fluid homeostasis.

• Development and Reproduction
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• v.15 no.2
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• pp.151-158
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• 2011

The comparison of the chemical properties of semen of black porgy Acanthopagrus schlegelii long-term acclimated reared in freshwater (BFW) and seawater (BSW) with sperm activity of salinity and ion composition. The chemical properties of seminal plasma on BFW of the factors that most there was not significant difference in the BSW. However, osmolality in seminal plasma of BFW and BSW was $307.0{\pm}4.6$ and $337.3{\pm}10.1$ mOsm/kg, respectively, where BFW showed significant lower concentration in contrast to BSW. Salinity effect on sperm motility of BFW and BSW in 0 psu solution, no sperm motility was observed, whereas in 10 psu solution, both BFW and BSW sperms showed low motility and short time post sperm activation. However, diluted in 20 and 32 psu solutions, highest motility and long time post sperm activation were observed in BFW and BSW sperm. SAI of BFW and BSW varied in depend on the osmolality regardless of ion kind and it showed the highest value in the similar osmolality of artificial seawater (956 mOsm/kg). Accordingly, even in sperm released from BFW, factors initiating sperm motility are determined by osmolality.

• Fisheries and Aquatic Sciences
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• v.15 no.3
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• pp.221-231
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• 2012

The marine medaka Oryzias dancena choriogenin H gene (odChgH) and its mRNA expression during estradiol-$17{\beta}$ (E2) exposure were characterized. At the amino acid level, the choriogenin H protein is predicted to possess the conserved repetitive N-terminal region, as well as zona pellucida (ZP) and Trefoil factor family (TFF) domains. At the genomic level, odChgH has an eight-exon organization with a distribution pattern of transcription factor binding sites in the 5'-upstream region, which is commonly found in other estrogen-responsive genes. The tissue distribution pattern of odChgH mRNA was found to be gender-specific, whereby females showed a higher expression level and wider tissue distribution than did males. During embryonic development, odChgH mRNA was robustly detected from the stage of visceral blood vessel formation. Experimental E2 exposure of males resulted in odChgH mRNA being induced not only in the liver, but also in other several tissues. The E2-mediated induction was fairly dose-dependent. The basal expression levels of hepatic odChgH mRNA were lower in males that were acclimated to 30 ppt salinity than in those acclimated to 0 or 15 ppt salinity. In contrast, the inducibility of odChgH mRNA during E2 exposure was greater in seawater-acclimated fish than in brackish water- or freshwater-acclimated fish.

• Journal of Aquaculture
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• v.18 no.1
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• pp.37-44
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• 2005

This study was conducted to compare the physiological conditions of black porgy (Acanthopagrus schlegeli) when reared in freshwater (0 psu) and seawater (35 psu) during 90 days. In terms of stress response, there was no significant difference in cortisol levels of the fish reared either freshwater or seawater until 60 days. Although cortisol level of fish reared in freshwater(12.6$\pm$5.0 ng/ml) was significantly higher than in seawater (4.5$\pm$2.9 ng/ml) at the end of experiment, these values were stable levels as compared with that of non-stressed fish. No significant differences in plasma osmolalities were recognized between the fish reared in freshwater (346.7$\pm$4.6$\~$356.5$\pm$2.1 mOsm/kg) and seawater (350.0$\pm$2.0$\~$357.0$\pm$22.6 mOsm/kg). Normal structure of gill lamellae without histological damage or cell necrosis has been observed in the fish reared in freshwater. In connection with growth and survival rate, total length and body weight of fish reared in freshwater were slightly longer and higher than those of fish reared in seawater. Survival rate of black porgy reared in freshwater was slightly higher than that of fish reared in seawater, but there was no significant difference. The results suggest that black porgy is reared with normal growth rate in freshwater without stress.

• Development and Reproduction
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• v.16 no.2
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• pp.77-85
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• 2012

Various cryoprotective agents (CPA) were tested to establish the best conditions for the cryopreservation of sperm from black porgy Acanthopagrus schlegeli acclimated and raised in freshwater (BFW). Survival rates of frozen/thawed sperm from BFW were higher in the order of dimethy sulfoxide (DMSO), glycerol, ethylene glycol (EG) and methanol. Sperm motility was higher in the order of glycerol, DMSO, EG and methanol. These effects were the same in thawed sperm from black porgy raised in seawater (BSW). Thus, optimum CPA for sperm cryopreservation of BFW and BSW were DMSO and glycerol where the highest survival rates and sperm motility were found at the concentration of 10%. In particular, the survival rates and motility of thawed sperm from BFW and BSW after cryopreservation using 10% DMSO were better than when cryopreserved using 10% glycerol. On the other hand, for the thawed sperm from both BFW and BSW, the longer the preservation period was, the lower the survival rates and sperm motility were. Notably, the higher the concentration of CPA was, the lower the survival rates and sperm motility were.

• 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.

• 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.

• Journal of Aquaculture
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• v.20 no.2
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• pp.121-126
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• 2007

Comparison of fish number on routine oxygen consumption (OC) of black porgy (Acanthopagrus schlegeli) reared in seawater (SW) versus freshwater (FW) was performed in closed water-recirculating system containing respiratory chamber. Fish acclimated in separate indoor tanks with SW or FW were sampled as two groups (one or three of fish used, $mean\;{\pm}\;S.D.=36.4{\pm}9.8$). OC of fish reared in both SW and FW showed clear temporal rhythms, with higher values in the daytime and lower values at night, in accordance with light (09:00-21:00 h) and dark (21:00-09:00 h) phases of the diel cycle (12L:12D). The OC of the fish increased linearly with the water temperature. The OCs of black porgy reared in SW and FW at 15, 20, $25^{\circ}C$ were 140.0, 174.8, 282.3 mg $O^2{\cdot}kg^{-1}{\cdot}h^{-1}$ and 177.5, 307.8, 413.1 mg $O^2{\cdot}kg^{-1}{\cdot}h^{-1}$ for the one of fish used, and 200.5, 274.7, 339.1 mg $O^2{\cdot}kg^{-1}{\cdot}h^{-1}$ and 118.2, 188.2, 252.8 mg $O^2{\cdot}kg^{-1}{\cdot}h^{-1}$ for three of fish used, respectively. Black porgy reared in SW had higher ventilation rates than those in FW. These results indicate that black porgy reared in FW had higher OC than those in SW at the one of fish used, but the fish reared in SW had higher OC than those in FW at the three of fish used.