• Journal of fish pathology
• /
• v.25 no.1
• /
• pp.11-20
• /
• 2012

C-type lectins are crucial for pathogen recognition, innate immunity, and cell-cell interactions. In this study, a C-type lectin gene was cloned from the rock bream. The full-length RbCTL cDNA was 729 bp with a 429 bp ORF encoding a 164-residue protein. The deduced amino acid sequence of RbCTL had all of the conserved features crucial for its fundamental structure, including the four cysteine residues involved in sulfide bridge formation and potential $Ca^2+$/carbohydrate-binding sites. RbCTL contains a signal peptide one single carbohydrate recognition domain. It showed 29.4% similarity to the C-type lectin of rainbow trout. RbCTL mRNA was predominately expressed in gill and head-kidney tissue and expressed less in peripheral blood leukocytes, trunk-kidney, spleen, liver, intestine and muscle. Expression of RbCTL was differentially upregulated in rock bream stimulated with LPS, Con A/PMA and poly I:C.

• Journal of Life Science
• /
• v.10 no.1
• /
• pp.24-27
• /
• 2000

For the rapid diagnosis of vibriosis in penaeid shirmp, the indirect fluorescent antibody technique(IFAT) was established to detect Vibrio alginolyticus. The titers of the antisera used for this experiment were above 1280. Vibrio alginolyticus possesses the specific antigen, and also have antigens shared with other strains. When an V. alginolyticus-infected adult shirmp was tested by IFAT, V. alginolyticus was detected mainly in the muscle tissues near the injection point and the haemolymph but only few in other tissues. This result indicates that the pathogen bacteria could be detected by IFAT. Thus, it is suggested IFAT is more convenient and sensitive method than conventional plate method for the diagnosis of induced Vibrio infection in the penaeid shrimps.

• Microbiology and Biotechnology Letters
• /
• v.38 no.1
• /
• pp.19-23
• /
• 2010

Recently, marine organisms are emerging as a leading group for identifying and extracting novel bioactive substances. These substances are known to possess a potential regarding not only as a source of pharmaceutical products but also their beneficial effects on humans. Among the substances, antimicrobial peptides (AMPs) specifically have attracted considerable interest for possible use in the development of new antibiotics. AMPs are characterized by relatively short cationic peptides containing the ability to adopt a structure in which cationic or hydrophobic amino acids are spatially scattered. Although a few reports address novel marine organisms-derived AMPs, their antimicrobial mechanism(s) are still remain unknown. In this review, we summarized the peptides previously investigated, such as Pleurocidin, Urechistachykinins, Piscidins and Arenicin-1. These peptides exhibited significant antimicrobial activities against human microbial pathogens without remarkable hemolytic effects against human erythrocytes, and their mode of actions are based on permeabilization of the plasma membrane of the pathogen. Therefore, the study of antimicrobial peptides derived from marine organisms may prove to be useful in the design of future therapeutic antimicrobial drugs.

• ALGAE
• /
• v.30 no.3
• /
• pp.217-222
• /
• 2015

Pythium species (Pythiales, Oomycetes) are well known as the algal pathogen that causes red rot disease in Pyropia / Porphyra species (Bangiales, Rhodophyta). Accurate species identification of the pathogen is important to finding a scientific solution for the disease and to clarify the host-parasite relationship. In Korea, only Pythium porphyrae has been reported from Pyropia species, with identifications based on culture and genetic analysis of the nuclear internal transcribed spacer (ITS) region. Recent fungal DNA barcoding studies have shown the low taxonomic resolution of the ITS region and suggested the mitochondrial cytochrome c oxidase subunit 1 (cox1) gene as an alternative molecular marker to identify Pythium species. In this study, we applied an analysis of both the ITS and cox1 regions to clarify the taxonomic relationships of Korean Pythium species. From the results, the two closely related Pythium species (P. chondricola and P. porphyrae) showed the same ITS sequence, while the cox1 marker successfully discriminated P. chondricola from P. porphyrae. This is the first report of the presence of P. chondricola from the infected blade of Pyropia yezoensis in Asia. This finding of the algal pathogen provides important information for identifying and determining the distribution of Pythium species. Further studies are also needed to confirm whether P. chondricola and P. porphyrae are coexisting as algal pathogens of Pyropia species in Korea.

• Journal of Microbiology and Biotechnology
• /
• v.26 no.8
• /
• pp.1457-1463
• /
• 2016

Vibrio anguillarum, a devastating pathogen causing vibriosis among marine fish, is prevailing in worldwide fishery industries and accounts for grievous economic losses. Therefore, a rapid on-site detection and diagnostic technique for this pathogen is in urgent need. In this study, two mouse monoclonal antibodies (MAbs) against V. anguillarum, 6B3-C5 and 8G3-B5, were generated by using hybridoma technology and their isotypes were characterized. MAb 6B3-C5 was chosen as the detector antibody and conjugated with quantum dots. Based on MAb 6B3-C5 labeled with quantum dots, a modified dot blot assay was developed for the on-site determination of V. anguillarum. It was found that the method had no cross-reactivity with other than V. anguillarum bacteria. The detection limit (LOD) for V. anguillarum was 1 × 10³ CFU/ml in cultured bacterial suspension samples, which was a 100-fold higher sensitivity than the reported colloidal gold immunochromatographic test strip. When V. anguillarum was mixed with turbot tissue homogenates, the LOD was 1 × 10³ CFU/ml, suggesting that tissue homogenates did not influence the detection capabilities. Preenrichment with the tissue homogenates for 12 h could raise the LOD up to 1 × 10² CFU/ml, confirming the reliability of the method.

• Journal of Aquaculture
• /
• v.21 no.1
• /
• pp.13-18
• /
• 2008

Marine birnavirus(MABV) are well known fish pathogens in Asian countries such as Korea, Japan, and China. Prevalence of viral disease, geological distribution and host or reservoir of viruses were investigated from wild marine fishes in southern coast of Korea in 2003 and 2005. RT-PCR results showed that MABV were detected in 17 fishes(10.6%) from 160 fishes. Comparative analysis of the nucleotide sequences and the deduced amino acids of MABV genome from wild fishes were similar to reference strains of MABV and distinguished with IPNV strains.

• Journal of Aquaculture
• /
• v.19 no.3
• /
• pp.197-204
• /
• 2006

The pathogenicity and infection route of the Scuticociliate, Philasterdies dicentrarchi, were investigated with the 3 and 5 cm-group of juvenile flounders, Paralichthys olivaceus. The infection rates of 3 cm-group were 40% four days post infection (D.P.I.) and increased to be 90.1% 24 D.P.I., whereas those of 5 cm-group were 20% 8 D.P.I., 42% 16 D.P.I., and 81% 24 D.P.I. The results showed there were several infection routes to internal organs Olive flounder. The first route was started with the infection at the soft part of caudal fin and later reached at fin ray and muscle tissue; the second one was started from lips and mouth tissue of upper jaw and later the pathogen could be observed at either muscle tissue or eyeball and brain; the third one was begun at caudal fin and later the pathogen reached at brain tissu'e through spiral cord; the fourth one was started with the infections at abdominal cavity and anus. P. dicentrarchi infected to brain tissue was first observed 14 D.P.I in 3 cm-group and 20 D.P.I. in 5 cm-group of the juvenile flounder. This indicated that the brain infection of P. dicentrarchi might occur faster in small-sized flounder than large-sized one.

• Fisheries and Aquatic Sciences
• /
• v.9 no.3
• /
• pp.123-128
• /
• 2006

An epizootic causing mortality among cultured marine finfishes occurred in 1999 in the province of Kyoungsang, Korea. The disease was characterized by the presence of enterocele, abdominal swelling, and gastroenteritis. The causative bacteria were isolated from olive flounder (Paralichthys olivaceus), black rockfish (Sebastes schlegeli), turbot (Scophthalmus maximus) and the rearing water. These bacteria showed swarming activity on agar plates and yellowish or greenish colonies on thiosulfate-citrate-bile salts-sucrose (TCBS) agar plates, but no luminescence. The pathogen was identified as Vibrio harveyi based on morphological and biochemical characteristics and the sequence of l6S rDNA. The lethal doses (LD$_{50}$) of olive flounder and black rockfish were estimated to be $1.24\times10^6-1.36\times10^8$ and $3.24\times10^5-5.8\times10^7$ CFU/fish respectively following intraperitoneal injection.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.48 no.5
• /
• pp.719-724
• /
• 2015

In this study aiming at the cultured olive flounders in Jeju island of Korea, has performed a total of 216 cases of pathogen tests for the olive flounders which seemingly had the symptom of emaciation in 24 farms on the suspicion of its occurrence from June 2010 to December 2013 and intended to get the basic information about the pathogen. According to the survey results of the emaciation infection status of 24 farms in Jeju over the period of this survey, it was confirmed that 18 (75%) of 24 farms in Jeju are positive in the emaciation infection. Among them, as for the rate of infection per year, it was observed that they are 38% in 2010, 48% in 2011, 50% in 2012 and 60% in 2013, and over the period of this survey the infection rate in accordance with the temperature of water has observed a variety of incidence rates from the summer to the winter season. In addition, according to the results of emaciation infection status for each size, the equivalent showed a detection rate, 54% in 11-20 cm, 43.9% in 21-30 cm and 25.4% in over 31 cm. This result accounts for an important portion among the diseases of farmed olive flounders in Jeju, is considered to be one of the diseases which cause troubles in the farms for olive flounders on land and it is thought that it can be utilized as basic data in order to estimate emaciation which may occur in the similar size of the cultured olive flounders in Jeju island.

• Journal of fish pathology
• /
• v.24 no.3
• /
• pp.297-305
• /
• 2011

A trap identification system for isolating functional sequences to allow the constitutive expression of foreign protein from Edwardsiella tarda was developed. Using the green fluorescent protein (GFP) reporter-based trap system, various functional sequences to drive heterologous expression of the GFP were selectable in Escherichia coli host. However from the bioinformatic sequence analysis, all the segments predicted as regulatory regions were not native promoters actually existing upstream of endogenous E. tarda genes. Instead, a number of non-authentic sequences, possibly resulted from the random shuffling and/or intermolecular ligation were also proven to be able to display a potent GFP expression in the recombinant E. coli. Further analysis with selected clones showed that both authentic and non-authentic sequences could function in as a constitutive promoter, leading quite a consistent and stable GFP expression after repetitive subcultures. Microscopic examination also confirmed the uniform pattern of GFP expression in every host bacterium. Semi-quantitative assay of GFP showed that there was no clear relationship between expression levels and organizational features of the promoters trapped. Functional promoter-like elements achieved in the present study could be a good starting material for multivalent genetic engineering of E. tarda in order to produce recombinant vaccines in a cost-effective fashion.