• Development and Reproduction
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• v.23 no.3
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• pp.239-253
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• 2019

We investigated the physiological responses of the river puffer, Takifugu obscurus, the tiger puffer, T. rubripes, a hybrids of the two (river puffer${\times}$tiger puffer) and a hybrid triploids to acute changes of salinity from 30 psu to 0 psu and from 0 psu to 30 psu. The blood and plasma factors of each species were elevated for 48, 72, or 96 hrs, and thereafter decreased due to hyper-osmoregulation and hypo-osmoregulation. In hyper-osmoregulation and hypo-osmoregulation, the cortisol concentration of river puffer, hybrids, hybrid triploids and tiger puffer increased for 12 or 48 hrs, and decreased thereafter. Chloride cells in the gill filaments of each species increased with increasing salinity, and melano-macrophages in the kidney tissue of each species increased with decreasing salinity. In conclusion, the hematological and stress responses of the hybrids were between those of the river puffer and tiger puffer, and the hematological responses of the hybrid triploids were higher than those of the other groups. The stress response of the hybrids was more sensitive than that of the hybrid triploids. In all groups, the histological responses of kidney in hyper-osmoregulation were more sensitive than those in hypo-osmoregulation.

• Journal of The Korean Society of Grassland and Forage Science
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• v.20 no.2
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• pp.77-84
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• 2000

Eight-week old perennial ryegrass (Lolium perenne L. cv. Reveille) plants were exposed to different NO3-concentrations or osmotic stress with NaCI. Previously labeled "N was chased during 14 days of non-labeled'NO3 feeding in order to investigate NO3 metabolism in relation to osmoregulation. The short termmeasurement of osmotic potential showed that the extemal concentration of Nos- had not great effect on theosmotic potential, but that osmotic adjustment was observed in NaCl-treated plants. Total uptake of NO 3 - waslargely increased by increasing supply level of NO3 while it was depressed by exposing to osmotic stress.Nitrate reduction increased to more than 29% by increasing extemal NO,- concentration from 1 mM to 10mM. When osmotically stressed with NaCI, nitrate reduction was depressed to about 37% as compared to thecontrol. The decrease in translocation of reduced N into leaves was also observed in NaCl exposed plants. Inthe medium exposed to 10 mM NO,., osmotic contribution of nitrate to cumulative osmotic potential wasdecreased, and it was osmotically compensated with soluble carbohydrate. When osmotically stressed withNaC1, the contribution of chloride was much higher than that of nitrate. The present data indicate that N03-in plant tissues, factually affected by the assimilation of this ion, plays an active role in osmotic regulation incorrelation with other osmotica such carbohydrate and chloride.(Key words : Nitrate metabolism, Osmotic stress, Nitrate supply level, Osmoregulation)ate supply level, Osmoregulation)

• Journal of Plant Biology
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• v.38 no.3
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• pp.243-250
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• 1995

Involvement of calcium in signal transduction of salt stress was investigated in 1.7 M NaCl adapted Dunaliella salina, extremely halotolerant, unicellular green alga. When hyperosmotic (3.4 M NaCl) or Hypoosmotic (0.8 M NaCl) stress was treated, extracellular calcium was influxed in or intracellular calcium effluxed from D. salina, respectively, and these fluxes were proportional to the degree of stress. This might indicate indirectly that the change of calcium level occurred within the cells. In addition, the change of calcium flux was ahead of glycerol synthesis which has been known as the physiological response to salt stress. Osmoregulation was affected byextracellular calcium concentration, and increase of glycerol content as an osmoticum was inhibited about 50% by treatment of TFP and W-7 known as calmodulin specific inhibitors. Furthermore, in the case of the hyperosmotic stressed cells, the amount of 21 kD and 39 kD protein appeared to be calcium binding protein were increased. Among these, the 39 kD protein was detected only in the hyperosmotic stressed cells. The results obtained in the present work suggest that the possibility of calcium as a second messenger in the transduction of salt stress signal exists in the osmoregulation system of D. salina.

• Korean Journal of Ichthyology
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• v.22 no.1
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• pp.9-16
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• 2010

Osmoregulatory capabilities of a euryhaline medaka, Oryzias dancena (Beloniformes; Teleostei), was examined with a particular emphasis on adult and larval viability during direct salinity changes. O. dancena adults were highly capable for hyper-osmoregulation as well as hypo-osmoregulation, as evidenced by no adverse effect on their viability during the direct transfer either from complete freshwater ($0^{\circ}/_{\circ\circ}$) to $40^{\circ}/_{\circ\circ}$ salinity, or from $70^{\circ}/_{\circ\circ}$ to $0^{\circ}/_{\circ\circ}$. Furthermore, the phased increase of external salinity with acclimation periods allowed them to survive at a salinity as high as $75^{\circ}/_{\circ\circ}$. However, tolerant capability to acute salinity increase in early larval stage was much less than in adult stage, based on the finding that the tolerance range of salinity increase was only $15^{\circ}/_{\circ\circ}$ from freshwater, indicating that the hyper-osmoregulation system might not be fully developed in the early larval stage. On the contrary, the hypoosmoregulation system could be more solidified in O. dancena larvae, as evidenced by their good survival even after direct transfer from $45^{\circ}/_{\circ\circ}$ to $0^{\circ}/_{\circ\circ}$. Knowledge achieved in this study could form the basis for a wide scope of researches including ecotoxicogenomics and geneexpression assay using this model species.

• Journal of Life Science
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• v.26 no.2
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• pp.164-173
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• 2016

Isotocin (IT), a nonapeptide homolog of oxytocin in mammals, has been suggested to be involved in physiological processes including social behaviors, stress responses, and osmoregulation in teleost fish. To study its structure and function, the gene encoding the IT precursor was cloned from the genomic DNA and brain cDNA of the cinnamon clownfish, Amphiprion melanopus. The IT precursor gene consists of three exons separated by two introns, and encodes an open reading frame of 156 amino acid (aa) residues, comprising a putative signal peptide of 19 aa, a mature IT protein of 9 aa, a proteolytic processing site of 3 aa, and 125 aa of neurophysin. Tissue-specific analysis of the IT precursor transcript indicated its expression in the brain and gonads of A. melanopus. To examine its osmoregulatory effects, the salinity of the seawater (34 ppt) used for rearing A. melanopus was lowered to 15 ppt. Histological analysis of the gills indicated the apparent disappearance of an apical crypt on the surface of the gill lamella of A. melanopus, as pavement cells covered the surface upon acclimation to the lower salinity. The level of Na⁺/K^+-ATPase activity in the gills was increased during the initial stage of acclimation, followed by a decrease to its normal level, suggesting its involvement in osmoregulation and homeostasis. The only slight increase in the level of IT precursor transcript in the A. melanopus brain upon low-salinity acclimation suggested that IT played a minor role, if any, in the process of osmoregulation.

• Journal of Microbiology
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• v.42 no.3
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• pp.174-180
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• 2004

A halophilic bacterium was isolated from fermented seafood. The 16S rDNA sequence identity between the isolate and Halomonas subglaciescola AJ306801 was above 95％. The isolate that did not grow in the condition without NaCl or in the condition with other sodium (Na$\^$+/) or chloride ions (Cl$\^$-/) instead of NaCl was named H. subglaciescola DH-l. Two mutants capable of growing without NaCl were obtained by random mutagenesis, of which their total soluble protein profiles were compared with those of the wild type by two-dimensional electrophoresis. The external compatible solutes (betaine and choline) and cell extract of the wild type did not function as osmoprotectants, and these parameters within the mutants did not enhance their growth in the saline environment. In the proton translocation test, rapid acidification of the reactant was not detected for the wild type, but it was detected for the mutant in the condition without NaCl. From these results, we derived the hypothesis that NaCl may be absolutely required for the energy metabolism of H. subglaciescola DH-l but not for its osmoregulation, and the mutants may have another modified proton translocation system that is independent of NaCl, except for those mutants with an NaCl-dependent system.

• Journal of Aquaculture
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• v.17 no.4
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• pp.246-250
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• 2004

Survival of 12.7 g (average body weight) Litopenaeus vannamei was examined at temperatures of 14, 16, 18, 28, 32, 34 and 36$^{\circ}C$ and salinities of l0, 20, 30 and 40 ppt after 7 days. Hemolymph osmolality was measured at 12 combinations of salinities (l0, 20, 30 and 40 ppt) and temperature levels (18, 28 and 34$^{\circ}C$) after 14 days. The results show that the species have their best survival between temperatures of 18 and 3$0^{\circ}C$ and salinity above 20 ppt. Hemolymph osmolality increased with increased salinity at all temperatures tested. The isosmotic point calculated from the linear relationship between hemolymph osmolality and medium osmolality and recorded as 826, 809 and 1,117 mOsm/kg which is equivalent to 29.4, 28.8 and 40.2 ppt at 18, 28 and 34$^{\circ}C$, respectively. The slopes obtained from the relationship between hemolymph osmolality and medium osmolality were 0.314, 0.276 and 0.541 for L. vannamei at 18, 28 and 34$^{\circ}C$, respectively, suggesting that the shrimp at 34$^{\circ}C$ regulated osmotic concentration much worse than those at 18 and 28$^{\circ}C$. This result also indicated that L. vannamei living at 34$^{\circ}C$, showed more fluctuation in hemolymph osmolality than those at 18 and 28$^{\circ}C$.

• Microbiology and Biotechnology Letters
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• v.47 no.1
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• pp.1-10
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• 2019

Saline soils comprise more than half a billion hectares worldwide. Thus, they warrant attention for their efficient, economical, and environmentally acceptable management. Halophytes are being progressively utilized for human benefits. The halophyte microbiome contributes significantly to plant performance and can provide information regarding complex ecological processes involved in the osmoregulation of halophytes. Microbial communities associated with the rhizosphere, phyllosphere, and endosphere of halophytes play an important role in plant health and productivity. Members of the plant microbiome belonging to domains Archaea, Bacteria, and kingdom Fungi are involved in the osmoregulation of halophytes. Halophilic microorganisms principally use compatible solutes, such as glycine, betaine, proline, trehalose, ectoine, and glutamic acid, to survive under salinity stress conditions. Plant growth-promoting rhizobacteria (PGPR) enhance plant growth and help to elucidate tolerance to salinity. Detailed studies of the metabolic pathways of plants have shown that plant growth-promoting rhizobacteria contribute to plant tolerance by affecting the signaling network of plants. Phytohormones (indole-3-acetic acid and cytokinin), 1-aminocyclopropane-1-carboxylic acid deaminase biosynthesis, exopolysaccharides, halocins, and volatile organic compounds function as signaling molecules for plants to elicit salinity stress. This review focuses on the functions of plant microbiome and on understanding how the microorganisms affect halophyte health and growth.

• Journal of Aquaculture
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• v.12 no.2
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• pp.123-135
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• 1999

In order to investigate the effect of salinity on growth and osmoregulation of the sweetfish, Plecoglossus altivelis, the fish (post-larva, juvenile, adult) reared in seawater were directly transferred into the experimental rearing water of the different salinities (post-larva : $0\textperthousand$, $5\textperthousand$, $10\textperthousand$, $15\textperthousand$, $20\textperthousand$, $30\textperthousand$. juvenile : $0\textperthousand$, $\10textperthousand$, $20\textperthousand$, $30\textperthousand$. adult : $0\textperthousand$, $15\textperthousand$, $35\textperthousand$, respectively). Fish samples were taken in time courses after transfer for blood and body fluid collection. The changes of sodium, potassium concentration and osmolality of the body fluid and plasma, muscle water content, gonadosomatic index (GSI) and hepatosomatic index (HSI) in the experimental fish were observed in time courses. Growth rate of the post-larva in $\5~25\textperthousand$ were faster than in $0\textperthousand$ (P<0.05). Survival rate was very low in $0\textperthousand$ (P<0.05). No fish survived more than 50 days after transferred into $0\textperthousand$. The concentration of sodium, potassium and osmolality in body fluid of the juvenile sweetfish were slightly decreased at 0.25 day after the beginning of the maintainable level of sodium, potassium and osmolality were $36.4\pm6.2 mM/\ell, 47.5\pm0.7 mM/\ell, 366.3\pm19.1 mOsm/kg, respectively. Except potassium concetration, fish in $0\textperthousand$ and $10\textperthousand$ displayed the pattern of hypoosmotic regulation. Growth rate and survival rate of juveniles of $30\textperthousand$ are significantly low than other groups (P＜0.05). The concentration of sodium, potassium and osmolality in plasma of adult sweetfish were slightly decreased at 1 day after the beginning of the maintainable level of sodium, potassium and osmolality were $159.0\pm2.5 mM/\ell, 5.8\pm0.9 mM/\ell, 338.1$\pm13.3 mOsm/kg respectively. Compared with these values, fish in $0\textperthousand$ and $15\textperthousand$ displayed hypoosmotic regultion. Growth and survival rate of adult in $35\textperthousand$ are significantly low than other experimental groups. GSI was the highest in $15\textperthousand$ after 60 days. HSI was the lowest in $35\textperthousand$. With decreased salinities, oxygen consumption was found to be decreased in the other experimental groups compared to the more than $30\textperthousand$.

• 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.