• Journal of fish pathology
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• v.6 no.1
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• pp.65-70
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• 1993

The delicate histological structure of gill in teleosts can be easily affected by a variety of biological, chemical or physical detrimental agents because it is directly exposed to the surrounding water. The epithelium of secondary lamella is thin to allow efficient gaseous exchange and this also renders it particularly vulnerable to various pathogens. As well as the main respiratory role, the gill has other various important functions such as acid-base balance, osmoregulation or the excretion of nitrogenous waste products. Thus destruction of epithelial integrity such as epithelial necrosis or thickening can render a fish very vulnerable to respiratory, secretory and excretory difficulties. This article was tried to describe in detail the common processes of pathological responses correlated to the normal histological structures of the gill in teleosts.

• Journal of Ecology and Environment
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• v.35 no.4
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• pp.351-358
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• 2012

To investigate the environmental adaptation and ecophysiological characteristics of Suaeda maritima and S. asparagoides under saline conditions, plant growth and density were analyzed according to environmental changes of habitats. The total ion content of soil decreased with time, which was caused by the predominance of exchangeable $Na^+$ and $Cl^-$ in the upper layers. The population of S. maritima was more densely distributed in the region with higher ion contents of $Cl^-$, $Mg^{2+}$, $K^+$ and $Na^+$ than the population of S. asparagoides. Both species were showed a decreased population density according to increases in plant growth. Under the conditions of a salt field, S. maritima and S. asparagoides contained high inorganic ions to maintain low water potential, but low water soluble carbohydrate contents. In the case of free amino acid, S. maritima showed an especially high proline content, and contained rather large amounts of free amino acids, whereas S. asparagoides did not. Both species showed high inorganic ion contents in the leaves, which might be a mechanism of avoiding the ionic toxicity by diluting the accumulated ionic concentration with a high ratio of water content to dry weight. This result suggests that S. maritima seems to adapt to saline conditions by accumulating proline in addition to inorganic ions. S. asparagoides seems to adapt by osmoregulation processes, using inorganic ions rather than free amino acids.

• Journal of Microbiology and Biotechnology
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• v.30 no.8
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• pp.1156-1168
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• 2020

Drought stress is threatening the growth and productivity of many economical crops. Therefore, it is necessary to establish innovative and efficient approaches for improving crop growth and productivity. Here we investigated the potentials of the cell-free extract of Actinobacteria (Ac) isolated from a semi-arid habitat (Al-Jouf region, Saudi Arabia) to recover the reduction in maize growth and improve the physiological stress tolerance induced by drought. Three Ac isolates were screened for production of secondary metabolites, antioxidant and antimicrobial activities. The isolate Ac3 revealed the highest levels of flavonoids, antioxidant and antimicrobial activities in addition to having abilities to produce siderophores and phytohormones. Based on seed germination experiment, the selected bioactive fraction of Ac3 cell-free extract (F2.7, containing mainly isoquercetin), increased the growth and photosynthesis rate under drought stress. Moreover, F2.7 application significantly alleviated drought stress-induced increases in H₂O₂, lipid peroxidation (MDA) and protein oxidation (protein carbonyls). It also increased total antioxidant power and molecular antioxidant levels (total ascorbate, glutathione and tocopherols). F2.7 improved the primary metabolism of stressed maize plants; for example, it increased in several individuals of soluble carbohydrates, organic acids, amino acids, and fatty acids. Interestingly, to reduce stress impact, F2.7 accumulated some compatible solutes including total soluble sugars, sucrose and proline. Hence, this comprehensive assessment recommends the potentials of actinobacterial cell-free extract as an alternative ecofriendly approach to improve crop growth and quality under water deficit conditions.

• Journal of Microbiology and Biotechnology
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• v.25 no.12
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• pp.1971-1976
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• 2015

Oceanobacillus kimchii is a member of the genus Oceanobacillus within the family Bacillaceae. Species of the Oceanobacillus possess moderate haloalkaliphilic features and originate from various alkali or salty environments. The haloalkaliphilic characteristics of Oceanobacillus advocate they may have possible uses in biotechnological and industrial applications, such as alkaline enzyme production and biodegradation. This study presents the draft genome sequence of O. kimchii X50^T and its annotation. Furthermore, comparative genomic analysis of O. kimchii X50^T was performed with two previously reported Oceanobacillus genome sequences. The 3,822,411 base-pair genome contains 3,792 protein-coding genes and 80 RNA genes with an average G+C content of 35.18 mol%. The strain carried 67 and 13 predicted genes annotated with transport system and osmoregulation, respectively, which support the tolerance phenotype of the strain in high-alkali and high-salt environments.

• The Korean Journal of Physiology and Pharmacology
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• v.1 no.5
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• pp.495-504
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• 1997

Water transport is mediated by two distinct pathways, diffusional and channel-mediated water transport. The first molecular water channel was identified from human erythrocytes in 1992. Genetically-related proteins from other mammalian tissues have subsequently been identified to transport water, and the group is referred to as th "Aquaporins". Aquaporin-4 (AQP4) is most abundant in the brain, which may be involved in CSF reabsorption and osmoregulation. However, ontogeny and regulatory mechanisms of AQP4 channels have not been reported. Northern blot analysis showed that AQP4 mRNA began to be expressed in the brain just before birth and that its expression gradually increased by PN7 and then decreased at adult level. AQP4 was expressed predominantly in the ependymal cells of ventricles in newborn rats. And then its expression decreased in ependymal cells and increased gradually in other regions including supraoptic and paraventricular nuclei. AQP4 is also expressed in the subfornical organ, in which the expression level is not changed after birth. Cryogenic brain injury did not affect expression of AQP4 mRNA, while ischemic brain injury decreased it. Osmotic water permeability of AQP4 channel expressed in Xenopus oocytes was inhibited by the pretreatment of BAPTA/AM and calmidazolium, a $Ca^{2+}/Calmodulin$ kinase inhibitor, in a dose-dependent manner. These results indicate that the expression and the function of AQP4 channel are regulated by developmental processes and various pathophysiological conditions. These results will contribute to the understanding of fluid balance in the central nervous system and the osmoregulatory mechanisms of the body.

• Journal of Ecology and Environment
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• v.39 no.1
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• pp.81-90
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• 2016

This study was to investigate the effect of salt stress on physiological characteristics such as plant growth, photosynthesis, solutes related to osmoregulation of Beta vulgaris. A significant increase of dry weight was observed in 50 mM and 100 mM NaCl. The contents of Chl a, b and carotenoid were lower in NaCl treatments than the control. On 14 day after NaCl treatment, photosynthetic rate (P_N), the transpiration rate (E) and stomatal conductance of CO₂ (g_s) were reduced by NaCl treatment. On 28 day after NaCl treatment, the significant reduction in g_s and E was shown in NaCl 200 mM. However, P_N and water use efficiency (WUE) in all NaCl treatments showed higher value than that of control. Total ion contents (TIC) and osmolality were higher than the control. On 14 day after treatment, the contents of proline (Pro) increased significantly in 200 mM and 300 mM NaCl concentration compared with control, whereas on 28 day in all treatments it was lower than that of the control. The contents of glycine betaine (GB) increased with the increase of NaCl concentration. The contents of Na⁺, Cl^-, GB, osmolality and TIC increased with the increase of NaCl concentrations. These results suggested that under severe NaCl stress conditions, NaCl treatment did not induce photochemical inhibition on fluorescence in the leaves of B. vulgaris, but the reduction of chlorophyll contents was related in a decrease in leaf production. Furthermore, increased GB as well as Na⁺ and Cl^- contents resulted in a increase of osmolality, which can help to overcome NaCl stress.

• 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.

• Animal cells and systems
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• v.16 no.5
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• pp.391-399
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• 2012

We cloned cDNA-encoding arginine vasotocin (AVT) from the brain of the cinnamon clownfish Amphiprion melanopus, and that was predicted to encode a protein of 153 amino acids. We examined changes in the expression of AVT mRNA in the brain and arginine vasotocin receptor (AVTR) mRNA and osmotic stress transcription factor 1 (OSTF1) mRNA in the gills of the cinnamon clownfish using quantitative real-time PCR in an osmotically changing environment (seawater (35 psu) ${\rightarrow}$ brackish water (BW, 17.5 psu) and BW with prolactin [PRL]). The expression of AVT, AVTR, and OSTF1 mRNA in the brain and gills increased after transfer to BW, and the expression was repressed by PRL treatment. AVT-immunoreactive cells were almost consistently observed in the telencephalon. The plasma $Na^+$ and $Cl^-$ levels decreased in BW, but the level of this parameter increased in BW with PRL treatme during salinity change. These results suggest that AVT, AVTR, and OSTF1 play important roles in hormonal regulation in osmoregulation organs, and that PRL improves the hyperosmoregulatory ability of cinnamon clownfish in BW environment.

• 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.49 no.5
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• pp.612-619
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• 2016

In this study, we crossbred Epinephelus akaara and E. lanceolatus to produce a hybrid grouper with faster growth and adaptation to domestic aquaculture environments. The plasma cortisol and glucose levels and osmoregulation (stress response indicators) of the hybrid grouper, E. akaara ♀ × E. lanceolatus ♂, were investigated under several salinity levels (32, 24, 16, and 8 psu). The body lengths and weights of E. akaara (8.2 ± 0.1 cm, 8.3 ± 0.4 g) and the hybrid (8.6 ± 0.1 cm, 10.0 ± 0.4 g) were similar at the start of the experiment, but were significantly different at the end of the experiment. Juveniles of both E. akaara and the hybrid showed greater weight gain, specific growth, and feed conversion rate (FCR) under low salinity of 16 psu. Under the 8 psu treatment, the juvenile E. akaara all died, while the hybrid juveniles survived. Plasma cortisol levels were not affected by lower salinity in both species. The above results indicate that the hybrid is more tolerant of low salinity than is E. akaara, although both species exhibited higher growth and FCR at 16 psu, lower than the salinity of natural seawater. Thus, juveniles of both E. akaara and the hybrid can be more effectively cultured in brackish areas or waters with salinity lower than that of seawater.