• Journal of fish pathology
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• v.25 no.3
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• pp.173-180
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• 2012

Vibriosis is one of the most prevalent fish disease belonging to the genus Vibrio. In present study, Vibrio sp. isolated from Japanese eel was confirmed as Vibrio scophthalmi using analysis of the genomic sequence of 16S rRNA. The major signs were hemorrhage of body surface and inner surface of abdomen, severe enteritis and retention of ascitis. Histopathological examination revealed blood cell degenerations in various organs (gills, liver, spleen, kidney, heart, intestine), exfoliate of intestinal epithelium, and congestion and hemorrhage in intestinal lamina propria. This is the first case report on V. scophthalmi infection in Japanese eel Anguilla japonica.

• Journal of fish pathology
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• v.34 no.2
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• pp.255-259
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• 2021

This is the first report describing acute mass mortality occurred in juvenile olive flounder (Paralichthys olivaceus) caused by gas bubble disease (GBD). A total of 610 fish (average weight = 35 g), which were more than half of the fish acclimated at 17℃ in an aquarium, were killed within two days of acclimation. The dead and moribund fish showed excessively opened opercula and mouths, and occasionally, severe exophthalmia. Through microscopic observation, numerous gas emboli were found in the gills of the dead and live fish, while the fish were not infected with any microbial pathogens. The dissolved oxygen (DO) saturation level of the rearing water and seawater nearby the facility reached 145% and 286%, respectively, whereas other water quality parameters (such as salinity, pH, and chemical oxygen demand) were normal. The extreme saturation rate of seawater in the shore nearby seemed to be due to an enormous algal bloom that occurred there. Through molecular identification based on 18S rDNA sequences, the most dominant algal species was most closely related to Ulva californica (99.87% sequence identity) followed by U. prolifera, U. linza, and U. curvata (99.81%). Therefore, it can be concluded that supersaturated seawater due to mass algal bloom caused gas bubble disease in the olive flounder, leading to mass mortality. After technical adjustment, such as increased aeration, lowered water circulation rate, and inlet water filtration using micro-pore carbon filters, the DO level became normal, no further mortality occurred and the status of the fish was stabilized.

• Fisheries and Aquatic Sciences
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• v.26 no.3
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• pp.188-203
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• 2023

Lysozymes are well-known antibacterial enzymes that mainly target the peptidoglycan layer of the bacterial cell wall. Animal lysozymes are mainly categorized as g-type, c-type, and i-type based on protein sequence and structural differences. In this study, c-type (AcLysC) and g-like-type (AcLysG-like) lysozymes from Amphiprion clarkii were characterized in silico via expressional and functional approaches. According to in silico analysis, open reading frames of AcLysC and AcLysG-like were 429 bp and 570 bp, respectively, encoding the corresponding polypeptide chains with 142 and 189 amino acids. Elevated expression levels of AcLysC and AcLysG-like were observed in the liver and the heart tissues, respectively, as evidenced by quantitative real-time polymerase chain reaction assays. AcLysC and AcLysG-like transcript levels were upregulated in gills, head kidney, and blood cells following experimental immune stimulation. Recombinant AcLysC exhibited potent lytic activity against Vibrio anguillarum, whereas recombinant AcLysG-like showed remarkable antibacterial activity against Vibrio harveyi and Streptococcus parauberis, which was further evidenced by scanning electron microscopic imaging of destructed bacterial cell walls. The findings of this study collectively suggest the potential roles of AcLysC and AcLysG-like in host immune defense.

• Fisheries and Aquatic Sciences
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• v.25 no.11
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• pp.559-571
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• 2022

Galectins, a family of ß-galactoside-binding lectins, have emerged as soluble mediators in infected cells and pattern recognition receptors (PRRs) responsible for evoking and regulating innate immunity. The present study aimed to evaluate the role of galectin-1 in the host immune response of redlip mullet (Liza haematocheilia). We established a cDNA database for redlip mullet, and the cDNA sequence of galectin-1 (LhGal-1) was characterized. In silico analysis was performed, and the spatial and temporal expression patterns in gills and blood in response to lipopolysaccharide polyinosinic:polycytidylic acid, and Lactococcus garvieae were estimated via quantitative real-time PCR. Functional assays were conducted using recombinant protein to investigate carbohydrate binding, bacterial binding, and bacterial agglutination activity. LhGal-1 was composed of 135 amino acids. Conserved motifs (H-NPR, -N- and -W-E-R) within the carbohydrate recognition domain were found in LhGal-1. The tissue distribution revealed that the healthy stomach expressed high levels of LhGal-1. The temporal monitoring of LhGal-1 mRNA expression in the gill and blood showed its significant upregulation in response to immune challenges with different stimulants. rLhGal-1 exhibited binding activity in response to carbohydrates and bacteria. Moreover, the agglutination of rLhGal-1 against Escherichia coli was observed. Collectively, our findings suggest that LhGal-1 may function as a PRR in redlip mullet. Furthermore, LhGal-1 can be considered a significant gene to play a protective role in redlip mullet immune system.

• Korean Journal of Ecology and Environment
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• v.43 no.3
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• pp.409-417
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• 2010

Present study aimed to investigate morphological and physiological change in the tissues of Carassius auratus after exposure against Pb (lead) with various rearing condition. We measured the level of accumulated heavy metal and analyzed ultrastructure with transmission electron microscopy. The heavy metal, Pb, was accumulated in the gill, bone and integument increased drastically for exposure periods, the 40 days. The accumulation of Pb in the gill showed relatively higher than that in other tissues. And accumulated Pb amounts also were increased with exposure time dependent manner in the gill, bone and integument tissues. Also, specific activities of antioxidation enzymes in all tissue after exposure to Pb were increased in the course of exposure. And the activities of SOD from tissues exposed to Pb were increased 2 folds than those from the unexposed but GPX activities were maintained constant. The increased numbers of mucous cells in gill tissues exposed to Pb were determined and morphological changes, such as clubbing and fusion, were shown secondary lamella. Also, exposure of Pb for 40 days on gills tissues cause membrane damage in mitochondria and nucleus. In kidney tissues, the atrophied glomerulus was observed, and the empty space in Bowman's capsule was expanded. Based on the all results, it is suggested that the exposure to the high level of Pb for long period affect on the morphology of tissues, and change the enzymatic balance in C. auratus.

• Korean Journal of Ecology and Environment
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• v.40 no.2
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• pp.244-253
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• 2007

In this study, mortality, body wet weight, health assessment, and short-term behavioral mode were observed to determine the effects of ultrasound on the ecological response of the carp Cyprinus carpio. Mortality in the treatments was less than 5% during ultrasound exposure (31 dB re 1 ${\mu}Pa$, $14{\sim}15$ kHz) and there were no significant differences among the replicates (P>0.05). The treatments, based on mean wet weight, exhibited greater effect than the controls, but the magnitude of the differences was not large. Skins and tail fins of some test animals exposed to the controls and intensive treatment groups had light injury such as hemorrhaging, whereas, damages in other organs such as eyes, other fins, parasites, thymus, and gills were not observed (P>0.05). Sudden stimuli in low intensity at a short distance caused a directional avoidance of the fish from the sound. However, the carp exposed to ultrasound at the large scale field was not observed clear behavior changes. Overall results suggest that fish exposed to the low-intensity ultrasound had no serious stress during the tests.

• Journal of Life Science
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• v.27 no.1
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• pp.50-56
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• 2017

An antibacterial peptide was purified from an acidified gill extract of the pufferfish Takifugu pardalis. The acidified gill extract was put through a Sep-Pak C18 solid phase extraction cartridge using a stepwise gradient and divided into a flow-through (F.T.) and 60% methanol fraction (RM 60). Among the eluents, RM 60 had potent antibacterial activity against Bacillus subtilis KCTC 1021. RM 60 was partially purified on a cationic-exchange column (SP-5PW) by a linear gradient, and the antibacterial peptide was then further purified, using a series of cationic-exchange and $C_{18}$ reversed-phase HPLC columns. For characterization of the purified peptide, its molecular weight and amino acid sequence were analyzed by MALDI-TOF MS and Edman degradation. The molecular weight of the peptide was about 1171.6 Da. The amino acid sequence of the peptide was partially determined as: STKEKAPRKQ. A comparison of the N-terminal amino acid sequence of the purified peptide with that of other known polypeptides revealed high homology with the N-terminus of the histone H3 protein, which belongs to the histone H3 family. Thus, this peptide was designated as a puffer fish gill (PFG)-related antimicrobial peptide. This is the report to describe an antimicrobial function for the N-terminus of histone H3 of an animal species. The findings suggest that this peptide plays a significant role in the innate defense system of the pufferfish.

• Journal of fish pathology
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• v.10 no.1
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• pp.21-29
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• 1997

We investigated on the prevalence and extermination of scuticociliatids parasitic on cultured japanese flounder, Paralichthys olivaceus in land-marine tank system of southern Korea from January to February in 1997. The gills and the skin showed the highest infection rate(60%), and the brain showed the lowest(22%). Also, fish secreted large quantity of mucus with a bleeding and ulcerated lesions on the infected sites. The number of the parasites in inflowing sea water, surface water and bottom water of farming tank ranged 0~1 individuals/$100m\ell$, 0~413 individuals/$100m\ell$ and $7\sim7.3{\times}10^4$ individuals/$100m\ell$, respectively. This parasite was died within 2 hours in 50~500 ppm, 48 hours of 10 ppm formalin or hydrogen peroxide, 1 hour in 50~500 ppm, 80 minutes of 10 ppm oligo chitosan and 10 minute in 100% but did not died until 48 hours in 10~70% fresh water.

• Korean Journal of Food Science and Technology
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• v.25 no.2
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• pp.185-190
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• 1993

Tilapia cultured in fresh water were acclimated in sea water with daily increase of $5%_{\circ}$ of salinity and it was completely terminated at the 7th day (0 week). Each three tilapia acclimated were examined weekly based from 0 week to elucidate changes of chloride cells in gill, mineral contents and physical properties in muscle and biochemical characteristics in myofibrils. Chloride cells existed in gills were gradually developed in number and size by acclimation to sea water and became to almost constant state at the third week. Shearing value, compressing strength and content of minerals such as Mg, Na and K in muscle were showed remarkable increase by acclimation to sea water in comparison to those of muscle from tilapia reared in fresh water. Myofibrillar $Mg^{2+}-,\;Ca^{2+}-$ and $K^+(EDTA)-ATPase$ activities of tilapia acclimated in sea water also increased showing significant statistic difference (p<0.01) from those of tilapia reared in fresh water However. thermostability of myofibrils was dropped by acclimation to sea water. The increase of shearing value and compressing strength in the muscle of tilapia by acclimation to sea water would be attributed to the increase of myofibrillar ATPase activities which act to accelerate the decomposition rate of ATP. Therefore, it is suggested that this phenomenon associated with muscle contraction could be brought an improvement of texture of tilapia acclimated in sea water.

• The Korean Journal of Malacology
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• v.31 no.3
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• pp.171-178
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• 2015

The reproductive ecology of freshwater bivalve, Unio douglasiae in Lake Uiam were examined from March 2014 to February 2015. The gonads distributed in reticular connective tissue, the dioecious clams take an internal fertilization and fertilized eggs are stored in the foster-sack in the gills, then the hatched juveniles are released outside after an ovoviviparous process. The gonad index (GI) began to increase in April, reached the maximum value in July and to decrease in August. The reproductive cycle of U. douglasiae can be divided into five successive stages: multiplicative stage (November to January), growing stage (February to March), mature stage (February to May), spawning stage (April to September), recovery stage (August to December). The spawning periods were from April to September, and the main spawning occurred between April and July. The shell length at 50% group maturity was estimated to be 29.4 mm.