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Cho J.Y.,Soonchunhyang University | Kim M.S.,South Korean National Fisheries Research and Development Institute
Bioscience, Biotechnology and Biochemistry | Year: 2012

An active antifouling diterpene was isolated from marine actinomycete strain PK209 and productivity was induced in a co-culture experiment. The active constituent was identified as the diterpene lobocompactol by interpretion of nuclear magnetic resonance and mass spectroscopy data. A PK209 co-culture was designed and a lobocompactol-resistant bacterium, KNS-16, was selected as co-culture competitor to induce lobocompactol production. Adding a small volume of 16-h-old KNS-16 culture to the 96-h-old PK209 culture caused rapid induction of lobocompactol production. The final yield was 2.7 mg/L, 10.4-fold higher than that collected from a single PK209 culture. The two bacteria, strains PK209 and KNS-16, were identified as Streptomyces cinnabarinus and Alteromonas sp. based on 16S rDNA sequencing. Lobocompactol showed significant antifouling activity, of 0.18 and 0.43 μg/mL, for EC50 against the macroalga Ulva pertusa and the diatom Navicula annexa respectively. It showed activity with MIC of 61-112 μg/mL against fouling bacteria.

Son S.,The Center for Satellite Applications and Research | Son S.,I-Systems | Wang M.,The Center for Satellite Applications and Research | Shon J.-K.,South Korean National Fisheries Research and Development Institute
Remote Sensing of Environment | Year: 2011

With the standard near-infrared (NIR) atmospheric correction algorithm for ocean color data processing, a high chlorophyll- a concentration patch was consistently observed from the Moderate Resolution Imaging Spectroradiometer (MODIS) onboard the Aqua platform in the middle of the Yellow Sea during the spring (end of March to early May). This prominent patch was not observed in the historical ocean color satellite imageries in late 1970s to early 1980s, and a location corresponding to this patch has been used as a Korean dump site since 1988. At the same time, MODIS chlorophyll- a concentrations derived using the shortwave infrared (SWIR) atmospheric correction algorithm developed for the ocean color satellite data in turbid coastal or high-productive ocean waters were significantly reduced. Comparison between in situ and MODIS chlorophyll- a measurements shows that the chlorophyll- a from the MODIS-Aqua products using the standard-NIR atmospheric correction algorithm is significantly overestimated. The images of the MODIS-derived normalized water-leaving radiance spectra and water diffuse attenuation coefficient data using the NIR-SWIR-based atmospheric correction approach show that absorption and scattering by organic and inorganic matter dumped in the Korean dump site have strongly influenced the satellite-derived chlorophyll- a data. Therefore, the biased high chlorophyll- a patch in the region is in fact an overestimation of chlorophyll- a values due to large errors from the standard-NIR atmospheric correction algorithm. Using the NIR-SWIR algorithm for MODIS-Aqua ocean color data processing, ocean color products from 2002 to 2008 for the Korean dump site region have been generated and used for characterizing the ocean optical and biological properties. Results show that there have been some important changes in the seasonal and interannual variations of phytoplankton biomass and other water optical and biological properties induced by colored dissolved organic matters, as well as suspended sediments. © 2010.

Kim G.,Seoul National University | Kim J.-S.,Seoul National University | Hwang D.-W.,South Korean National Fisheries Research and Development Institute
Limnology and Oceanography | Year: 2011

We investigated submarine groundwater discharge (SGD)-associated nutrient fluxes and budgets in two coastal embayments, Hwasun Bay and Bangdu Bay, off the volcanic island of Jeju, Korea. SGD in Hwasun Bay is a composite of marine and meteoric groundwater, while that in Bangdu Bay mainly includes marine groundwater. The submarine inputs of groundwater into Hwasun and Bangdu Bays were approximately 0.12 and 0.27 m3 m-2 d-1, respectively, on the basis of the 222Rn mass balance models. The nitrogen : phosphorus ratios in coastal groundwater (85 ± 96) were considerably larger than those in the seawater (3.8 ± 1.6) of both bays. Fluxes of dissolved inorganic nitrogen (DIN) through SGD were more than 90% of the net DIN input into both bays; approximately 93% and 39% of SGD-driven DIN was consumed inside Hwasun and Bangdu Bays, respectively. The discharge of DIN through SGD from the entire island was approximately 2.1 × 109 mol yr-1, which is equivalent to that of some large rivers, potentially supporting approximately 1.6 × 1011 g carbon yr-1 of new primary production. Because Jeju accounts for less than 1% of the total land mass of the volcanic islands, SGD-driven nutrient fluxes from highly permeable islands standing in oligotrophic oceans could be very important for global nutrient budgets. © 2011, by the American Society of Limnology and Oceanography, Inc.

Gopalakannan A.,South Korean National Fisheries Research and Development Institute | Arul V.,Pondicherry University
Aquaculture Research | Year: 2010

The effects of dietary β- (1,3) glucan and whole cell yeast (Sacharomyces uvarum) on the immune response and disease resistance to Aeromonas hydrophila were investigated in Cyprinus carpio. β-(1,3) glucan was extracted from the yeast. Both β-(1,3) glucan and whole yeast were incorporated into the diet at 1% level and fed to common carp C. carpio for a period of 60 days. Control and treated fish were exposed to A. hydrophila on the 30th and the 60th day of the experimental period. Dietary supplementation of glucan significantly increased the white blood cell count in fish on the 60th day (2.91±0.04 × 104), and the highest nuetrophil nitro blue tetrazolium (NBT) activity was also observed in glucan-fed fish (30th day). A consistent increase in neutrophil (NBT) activity was also observed in whole cell fed fish until the end of the experiment. Similarly, β-(1,3) glucan and whole cell yeast enhanced the serum lysozyme activity from the 15th day onwards but higher activity was reported on the 30th day in glucan and the 60th day in whole cell yeast-fed fish. Suplementation of β-(1,3) glucan protected the fish from A. hydrophila infection. Nearly 75-80% of the fish survived pathogen exposure (relative percentage survival). However, only 54-60% survival was observed in the whole cell-fed fish. β-(1,3) glucan and whole cell yeast protect the fish from pathogens by enhancing the cellular and humoral immune response in C. carpio. © 2009 V. Arul. Journal Compilation © 2009 Blackwell Publishing Ltd.

Kang J.H.,South Korean National Fisheries Research and Development Institute
Genetics and molecular research : GMR | Year: 2012

Distributed along the coastal waters of Korea and China, Octopus minor is found in various habitats, including the mud flats in the southern and western coasts of the Korean Peninsula and the rocky areas around Jeju Island; however, the genetic relationships among the different populations are unknown and have not been studied. We compared 630-nucleotide sequences of the CO1 gene from O. minor specimens collected from five regions around the Korean Peninsula and three regions from eastern China in order to determine population structure and genetic relationships. Based on the sequences at 12 polymorphic sites in this region, 11 haplotypes were identified from 85 specimens. Individuals from Jeju Island had unique haplotypes, including two haplotypes not found in the other populations. Nucleotide and haplotype diversity for all populations ranged from 0.03-0.37 and 0.20-0.64, respectively. Pairwise F(ST) values indicated significant genetic differences in populations from Korea and China. An UPGMA dendrogram showed separation of the eight populations into three clusters; one included only the Jeju population, another included the rest of the Korean populations and some from Dalian, China; a third cluster consisted of two other populations from China. We conclude that there are discrete genetic differences in O. minor from the different habitats, suggesting that the populations should be considered as management units in the ongoing recovery program.

Park H.-H.,South Korean National Fisheries Research and Development Institute
Ocean Engineering | Year: 2014

An estimation of the gear shape during a bottom trawl can be achieved through geometrical modeling of the trawl system. This can be implemented by processing the field data obtained using the Scanmar system. The gear shape from the square through the bag net was assumed to be the upper and lower parts of different elliptic cones of which the cross section was an ellipse and the shape of the float rope to be of exponential function. A system of nonlinear equations was constructed to represent the gear shape of the bottom trawl net in water. When the equations were solved based on the data obtained from bottom trawl experiments with various warp lengths, the cross section of sweep and filtered volume, the eccentricity of the upper ellipse, the functional shape and inclination angle of the float rope, and the contribution of the upper side panel to the net height could be obtained in relation to towing speed and scope ratio. As the cross section of sweep at the mouth and the projected total cross section decreased a little bit with increased towing speed, the filtered volume tended to increase with increased towing speed. The gear shape at mouth of the bottom trawl was not so much changed compared to that of a mid-water trawl. © 2014 Elsevier Ltd.

Park T.-G.,South Korean National Fisheries Research and Development Institute | Park Y.-T.,South Korean National Fisheries Research and Development Institute
Harmful Algae | Year: 2010

Recurring blooms of fish killing dinoflagellate Cochlodinium polykrikoides has resulted in large economic losses in fisheries industry in Korea. This species has been monitored in water column samples, but its spatial distribution in sediments is poorly understood. To address this area, geographic distribution of C. polykrikoides and morphologically similar species Gymnodinium impudicum in surface sediments of Korea was investigated using species-specific real-time PCR probes targeting the internal transcribed spacer 2 rRNA gene. PCR-inhibitory substances in sediment samples were removed by dilution of DNA extracts from the field samples for preventing false-negative detection. G. impudicum was widely distributed in sediments from East, South, and Yellow Seas. C. polykrikoides was prevalent in sediments from South Sea whereas it was not detected in sediments from East and Yellow Seas. These results indicate that these dinoflagellates may persist in surface sediment likely in the form of cyst and their "seed beds" may exist in sediments of South Sea where blooms of C. polykrikoides occur annually. © 2009 Elsevier B.V. All rights reserved.

An H.S.,South Korean National Fisheries Research and Development Institute | Lee J.W.,South Korean National Fisheries Research and Development Institute
International Journal of Molecular Sciences | Year: 2012

Mytilus coruscus (family Mytilidae) is one of the most important marine shellfish species in Korea. During the past few decades, this species has become endangered due to the loss of habitats and overfishing. Despite this species' importance, information on its genetic background is scarce. In this study, we developed microsatellite markers for M. coruscus using next-generation sequencing. A total of 263,900 raw reads were obtained from a quarter-plate run on the 454 GS-FLX titanium platform, and 176,327 unique sequences were generated with an average length of 381 bp; 2569 (1.45%) sequences contained a minimum of five di- to tetra-nucleotide repeat motifs. Of the 51 loci screened, 46 were amplified successfully, and 22 were polymorphic among 30 individuals, with seven of trinucleotide repeats and three of tetranucleotide repeats. All loci exhibited high genetic variability, with an average of 17.32 alleles per locus, and the mean observed and expected heterozygosities were 0.67 and 0.90, respectively. In addition, cross-amplification was tested for all 22 loci in another congener species, M. galloprovincialis. None of the primer pairs resulted in effective amplification, which might be due to their high mutation rates. Our work demonstrated the utility of next-generation 454 sequencing as a method for the rapid and cost-effective identification of microsatellites. The high degree of polymorphism exhibited by the 22 newly developed microsatellites will be useful in future conservation genetic studies of this species. © 2012 by the authors; licensee MDPI, Basel, Switzerland.

Kong H.J.,South Korean National Fisheries Research and Development Institute
International journal of molecular sciences | Year: 2013

We identified and characterized the primary structure of the Korean oily bitterling Acheilognathus koreensis fast skeletal myosin light chain 2 (Akmlc2f), gene. Encoded by seven exons spanning 3955 bp, the deduced 168-amino acid AkMLC2f polypeptide contained an EF-hand calcium-binding motif and showed strong homology (80%-98%) with the MLC2 proteins of Ictalurus punctatus and other species, including mammals. Akmlc2f mRNA was highly enriched in skeletal muscles, and was detectable in other tissues. The upstream regions of Akmlc2f included a TATA box, one copy of a putative MEF-2 binding site and several putative C/EBPβ binding sites. The functional activity of the promoter region of Akmlc2f was examined using luciferase and red fluorescent protein reporters. The Akmlc2f promoter-driven reporter expressions were detected and increased by the C/EBPβ transcription factor in HEK293T cells. The activity of the promoter of Akmlc2f was also confirmed in the developing zebrafish embryo. Although the detailed mechanism underlying the expression of Akmlc2f remains unknown, these results suggest the muscle-specific expression of Akmlc2f transcript and the functional activation of Akmlc2f promoter by C/EBPβ.

Nam B.H.,South Korean National Fisheries Research and Development Institute
Comparative biochemistry and physiology. Part B, Biochemistry & molecular biology | Year: 2013

We identified full-length cDNAs encoding pituitary adenylyl cyclase-activating polypeptide (PACAP), PACAP-related peptide (PRP), and PACAP-specific receptor (PAC1R) from olive flounder, Paralichthys olivaceus. Two variant mRNA forms were created by alternative splicing. Comparison of genomic and cDNA sequences of the PRP-PACAP precursor revealed that skipping of exon 4 within PRP resulted in two variant transcripts: a long form encoding both PRP and PACAP and a short form encoding PACAP only. Both transcripts were constitutively observed only in the brain, whereas the short form appeared in gut tissues, such as the intestine and pyloric cecum in fish challenged with a pathogen, but not in healthy fish. Furthermore, expression of the long PRP/PACAP transcript gradually increased in the intestine of flounder challenged with bacteria, suggesting that PRP and/or PACAP may serve as a regulator(s) of the immune system, especially in the gastrointestinal tract of olive flounder. The biological functions of PACAP and PRP were investigated by exogenous treatment of flounder embryogenic cells (hirame natural embryonic cells, HINAE cells) with synthetic peptides of fPACAP-38 and/or fPRP-45. Intracellular cyclic adenosine monophosphate (cAMP) production in PAC1R-overexpressing HINAE cells was regulated by fPACAP-38 in a concentration-dependent manner, but was not regulated by fPRP-45. Results from real-time quantitative polymerase chain reaction revealed that PAC1R mRNA was specifically induced by fPACAP-38 but not by fPRP-45; PACAP significantly increased TNF-α mRNA but not growth hormone (GH) mRNA in HINAE cells; however, PRP affected GH but not TNF-α mRNA expression. These results suggest that the expression ratio of PRP and PACAP is regulated at the transcriptional level depending on the tissues and conditions, and that the unique biological roles of PRP and PACAP differ from that of mammalian PRP. Copyright © 2012 Elsevier Inc. All rights reserved.

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