• Korean Journal of Fisheries and Aquatic Sciences
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• v.17 no.5
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• pp.414-422
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• 1984

This research was conducted to evaluate the effect of polluted Oncheon Stream on the marine organisms in the Suyeong Bay. Water quality and 96 hr acute toxicity to the sea urchin, Hemicentrotns pulcherrimus by recirculation bioassay were examined from Feb. 20 to Apr. 15, 1984. The 96 hr $50\%$ effective concentration($EC_{50}$) on the attachment of the podia of the sea urchin was observed to occur at test concentrations between 40.0 and $51.0\%$ (v/v), and safe concentrations may be assumed to be within 4.0 and $5.1\%$. These values indicate as follows : 1. Oncheon Stream was extremely polluted by oxygen-demanding wastes and synthetic organic compounds from sewage and industrial waste water. 2. Linear alkylbenzene sulfonate(LAS) which has not been yet included in water quality standard was discharged above the TLm. 3. Unknown toxicity may be synergy among complex substances. In consideration of the relationship between COD values of Oncheon Stream and dilution water, the effect of toxicity of Oncheon Stream water reached to the area of the Suyeong Bay where the COD value was found to be 12.2 ppm.

• Korean Journal of Ichthyology
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• v.29 no.2
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• pp.146-150
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• 2017

Length and weight relationship (LWR) for dominant Antarctic fishes was determined in two species of the family Nototheniidae; black rockcod (Notothenia coriiceps) and marbled rockcod (Notothenia rossii). Samples were caught in the offshore sea around King Sejong station located on King George Island, Antarctica in January, 2017. A total of 30 N. coriiceps and 7 N. rossii were caught by fishing rod and hook. Average total length was 266.0 mm for N. coriiceps and 275.4 mm for N. rossii. Average total weight was 283.1g for N. coriiceps and 290 g for N. rossii. In terms of LWR and b value, the results showed that both two species had positive allometries (b>3) in good health. This size information of two dominant Antarctic fishes would be useful for future physiological studies to understand of adaptation mechanism and biological pathway of Antarctic marine organisms.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.8
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• pp.3785-3791
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• 2012

Dissolved oxygen is one of the most important factors controlling growth in aquatic organisms. Hypoxia is generally defined as dissolved oxygen less than 2.8 mg $O_2/L$ (equivalent to 2 mL $O_2/L$ or 91.4 mM). Therefore, hypoxia zone can cause a serious problem in marine ecosystem. In this study, to investigate embryotoxic (fertilization and embryo development rates) effects of hypoxia on sea urchin Strongylocentrotus nudus were exposed to dissolved oxygen levels of 7.6 mg $O_2/L$ (normoxia) and 1.8 mg $O_2/L$ (hypoxia) for 2 days at $15^{\circ}C$ and 33 ‰. Also, Expression levels of stress related gene (HSP70) and antioxidant related gene (glutathione reductase) in the sea urchins exposed to hypoxia were confirmed by Immunoblotting and RT-PCR analysis. In results, we showed that developmental rates were dramatically reduced in hypoxia condition. Molecular analysis demonstrated that higher HSP70 (5.5 fold) and glutathione reductase gene (2.79 fold) were present in the sea urchin exposed to hypoxia. Our results suggested that hypoxia can cause the abnormal development and elicits a stress and antioxidant response on sea urchin.

• Journal of the Korean Society of Food Science and Nutrition
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• v.29 no.5
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• pp.922-934
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• 2000

To investigate the composition of carotenoids present in marine organisms and the biological activity of the carotenoids, carotenoids of the muscles and tunic of tunicates and shellfishes were isolated and identified. Anitmutagenic activities of the carotenoids for S. typhimurium TA 98 and cytotoxic activity for cancer cell lines were determined. Total carotenoid contents in the muscle of tunicata ranged from 18.65 mg% to 2.39 mg%. The highest amount of the total carotenoid was found in the muscle of Halocynthia aurantium, followed by Styela clava (HERDMAN), H. roretzi, H. hilgendorfi f. igaboya, H. hilgendorfi f. retteri, S. plicata (LESUEUR) in order. Interestingly, total carotenoid content in the muscle of S. clava (HERDAMAN) was higher than that of H. roretzi. Total carotenoid content of all tunicata, other than H. aurantium and H. roretzi, were higher in muscle than tunic. The major carotenoids in H. roretzi, H. aurantium, S. plicata (LESUEUR), and S. clava (HERDAMAN) were cynthiaxanthin (25.1∼42.2%), halocynthiaxanthin (9.7∼26.3%), diatoxanthin (8.0∼18.7%) and β-carotene (7.7%∼21.7%). Similarly, cantaxanthin (19.6%), cynthiaxanthin (15.4%), halocynthiaxanthin (14.8%), and (3R, 3'R), (3S, 3'S)-astaxanthin (22.6%) in H. hilgendorfi f. retteri and fucoxanthin (26.6%), cynthiaxanthin (21.8%), halocynthiaxanthin (15.2%), and β-carotene (9.3%) in H. hilgendorfi f. igaboya were major carotenoids in both tunicate. However, the composition of carotenoids in muscle and tunic of tunicata was similar each other. Among the shellfishes examined, total carotenoid content of the muscle of Peronidia venulosa (Schrenck) and Corbicula fluminea, and of the gonad of Atrina pinnata and Chlamys farreri, was ranged from 2.51 to 6.83 mg% which were relatively higher than that of other shellfishes. The composition of the carotenoids of shellfishes, which might depend upon their living environments, was varied. But cynthiaxanthin (15.9∼39.0%) and zeaxanthin (9.6∼21.9%) in gonad of C. farreri, and muscles of Buccinum Volutharpa perryi (JAY) and Crassostrea gigas, cynthiaxanthin (21.5∼48.6%) and mytiloxanthin (14.6%) in muscle of C.fluminea and gonad of A. pinnata, and canthaxanthin (60.6%) and isozeaxanthin (20.5%) in muscles of P. venulosa (Schrenck), and β-carotene (23.7%∼37.8%) and zeaxanthin (18.2∼20.4) in muscles of Semisulcospira libertina and Meretrix lusoria were major carotenoids. Interestingly, diester type-carotenoids were present along with free type-carotenoids in muscles of C. gigas. antimutagenic effect of the carotenoids isolated from tunicata and shellfishes against 2-amino-3-methylimidazol [4,5-f]quinoline (IQ) for S. typhimurium TA 98 was proportional to the amount (20, 50 and 100㎍/plate) treated. Mutagenicity of IQ was significantly reduced by astaxanthin, isozeaxanthin, mytiloxanthin and halocynthiaxanthin, whereas the mutagenicity of aflatoxin B₁(AFB₁) was significantly reduced by β-carotene, isozeaxanthin, and mytiloxnthin. Growth inhibition effect of carotenoids isolated from tunicata and shellfishes for cancer cell was proportional to the amount (5, 10, and 20㎍/plate) treated. The growth of HeLa cell by β-carotene, cynthiaxanthin, astaxanthin and halocynthiaxanthin, NCI-H87 cell by β-carotene, astaxanthin, cynthiaxanthin, and halocynthiaxanthin, HT-29 cell by β-carotene, cynthiaxanthin, mytiloxanthin and halocynthiaxanthin, and MG-63 cells by β-carotene, cynthiaxanthin, astaxanthin, canthaxanthin and halocynthiaxanthin were statistically reduced.

• Journal of Sericultural and Entomological Science
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• v.50 no.2
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• pp.53-62
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• 2012

Silkworm larvae often suffer from viral infections causing heavy losses to the economy of silk industry. Insects exhibit both humoral and cellular immune responses that are effective against various pathohens like bacteria, fungi, protozoa, etc., but no insect immune responses is effective against viral infection. To obtain genes related to insect antiviral immunity from Bombyx mori, the cDNA library was constructed from B. mori nucleopolyhedrovirus (BmNPV)-infected B. mori. From the cDNA library, we selected 411 differentially expressed clones, and the 5' ends of the inserts were sequenced to generate ESTs. In this work, 135 unigenes were generated after the assembly of 411 differentially expressed clones ESTs. Of these 135 unigenes, we selected 109 antiviral response-related candidates except 26 clones that high similarity with genes derived from BmNPV. Among 109 unigenes, a total of 80% had significant matches to genes from other organisms in the database, wheres 20% of the unigenes had not matched in the database. Functional groups of these sequences with matches in database were constructed according to their putative biological function. Three largest categories were control of cellular oraganization (52%), metabolism (20%), and protein fate (10%). The genetic information reported in this study will provide more information about antiviral-related genes in silkworms.

• Journal of Life Science
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• v.31 no.9
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• pp.862-872
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• 2021

Recent studies on synthesis of metallic nanomaterials such as silver (Ag), gold (Au), platinum (Pt), cerium (Ce), zinc (Zn), and copper (Cu) nanoparticles (NPs) using plants and microbes are attracted researchers for their wide range of applications in the field of biomedical sciences. The plant contains abundant of bioactive contents such as flavonoids, alkaloids, saponins, steroids tannins and nutritionals components. Similarly, microbes produce bioactive metabolites, proteins and secretes valuable chemicals such as color pigments, antibiotics, and acids. Recently reported, biogenic synthesis of NPs in non-hazardous way and are promising candidates for biomedical applications such as antibacterial, antifungal, anti-cell proliferative and anti-plasmodia activity. All those activities are dose dependent, along with their shape and size also matters on potential of NPs. Microbes and plants are great source of metabolites, those useful in biomedical field, such metabolites or chemicals involved in synthesis of NPs in an ecofriendly way. NPs synthesized using microbes or plant materials are reveals more non-toxic, facile, and cost-effective compare to chemically synthesized NPs. In present review we are focusing on NPs synthesis using biological agents such as microbes (bacteria, fungi and algae) and plant, characterization using different techniques and their antibacterial applications on pathogenic Gram-positive and Gram-negative organisms.

• ALGAE
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• v.34 no.3
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• pp.237-251
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• 2019

The dinoflagellate genus Alexandrium is known to often form harmful algal blooms causing human illness and large-scale mortality of marine organisms. Therefore, the population dynamics of Alexandrium species are of primary concern to scientists and aquaculture farmers. The growth rate of the Alexandrium species is the most important parameter in prediction models and nutrient conditions are critical parameters affecting the growth of phototrophic species. In Korean coastal waters, Alexandrium affine and Alexandrium fraterculus, of similar sizes, often form red-tide patches together. Thus, to understand bloom dynamics of A. affine and A. fraterculus, growth rates and nitrate uptake of each species as a function of nitrate ($NO_3$) concentration at $100{\mu}mol\;photons\;m^{-2}s^{-1}$ under 14-h light : 10-h dark and continuous light conditions were determined using a nutrient repletion method. With increasing $NO_3$ concentration, growth rates and $NO_3$ uptake of A. affine or A. fraterculus increased, but became saturated. Under light : dark conditions, the maximum growth rates of A. affine and A. fraterculus were 0.45 and $0.42d^{-1}$, respectively. However, under continuous light conditions, the maximum growth rate of A. affine slightly increased to $0.46d^{-1}$, but that of A. fraterculus largely decreased. Furthermore, the maximum nitrate uptake of A. affine and A. fraterculus under light : dark conditions were 12.9 and $30.1pM\;cell^{-1}d^{-1}$, respectively. The maximum nitrate uptake of A. affine under continuous light conditions was $16.4pM\;cell^{-1}d^{-1}$. Thus, A. affine and A. fraterculus have similar maximum growth rates at the given $NO_3$ concentration ranges, but they have different maximum nitrate uptake rates. A. affine may have a higher conversion rate of $NO_3$ to body nitrogen than A. fraterculus. Moreover, a longer exposure time to the light may confer an advantage to A. affine over A. fraterculus.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.24 no.1
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• pp.18-29
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• 2019

ROV surveys were conducted using 500 meter mini class ROV with HD video camera, 2 LED lights, a simple manipulator and 8 thrusters near the Dokdo and Simheungtaek seamount. Total six dives have been conducted using the ROV "V8 SII" from Sweden and ROV's support ship, "KOSAL V" at 4 stations between 45 and 370 meters with diving time ranged from 30 to 120 minutes. Dense communities of sea anemone (Actinostolidae sp.) and ophiuroids (Ophiuridae sp.) on the surface of rocky bottom and snow crab on the soft bottom with muddy-sand were observed at northwestern part of Simheungtaek seamount. We obtained the following results 1) habitats information for snow crab, one of the major fisheries resources, and deep-sea fauna, 2) observation on the specific topography and sediment conditions, 3) observation of the seabed surface covered with the discarded fishing gears. This study represents the first report of in situ visual observation of deep-sea organisms and their habitats near the Dokdo slopes and flat top of the Simheungtaek seamount in the East Sea. These results indicated that immediate oceanographic survey using the mini class ROV is available in the East Sea.

• The Korean Journal of Mycology
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• v.48 no.4
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• pp.381-388
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• 2020

Bioluminescence refers to the production and emission of light in living organisms. This phenomenon arises from luciferase-catalyzed oxidation reaction of luciferin. Bioluminescence is widely observed in marine vertebrates and invertebrates, as well as in some microorganisms and fungi. To date, approximately 80 species of fungi have been reported to be luminous. One such example is Omphalotus japonicus, which is a luminous fungus found in Korea. In this study, we examined the bioluminescence of Omphalotus japonicus mycelia. Light emission was detected at the edges of mycelia grown on solid agar medium. Notably, the intensity of bioluminescence was found to be significantly enhanced following wound induction. The increase in light intensity peaked at 3 h after mechanical damage. We also investigated the effects of extreme temperatures on bioluminescence. Unlike mechanical damage, high and low temperatures repressed the light emission from mycelia. Further investigations are required to reveal the physiological and ecological properties of fungal bioluminescent responses to environmental stresses.

• Journal of the Korea institute for structural maintenance and inspection
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• v.26 no.1
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• pp.67-72
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• 2022

Concrete prevents corrosion of reinforcing bars due to its strong alkalinity. However, in the sea, strong alkali components with a pH of 12 to 13 are eluted, which adversely affects the ecological environment and growth of marine organisms. In this study, the mechanical properties and durability of the low alkali mortar were evaluated for the development of a low alkali mortar for the 3D printed artificial reefs. As a result of evaluation of strength characteristics, the α-35 mixture, which were produced with fly ash, silica fume and α-hemihydrate gypsum, satisfied the strength requirement 27 MPa in terms of compressive strength. As a result of pH measurement, it was found that mixing with alpha-type hemihydrate gypsum resulted in minimizing pH due to the the formation of calcium sulfate instead of calcium hydroxide production. As a result of the chloride ion penetration resistance test, the α-35 mixture exhibited the best performance, 3844C. As a result of measuring the length change over time, the α-35 mixture showed the shrinkage 33.5% less compared to the Plain mix.