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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. Source

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. Source

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. Source

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. Source

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. Source

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