• The Korean Journal of Food And Nutrition
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• v.13 no.4
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• pp.334-341
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• 2000

The DMPT produced by marine algae is the main biogenic precursor of oceanic DMS. Also, DMPT is an efficient stimulant for growth, feeding, and body movement of fish and striped prawn, and appears to play a physiologic role as an osmoprotectant in algae. This study was focused on the extraction of dimethyl-$\beta$-propiothetin as bioactive substance from green seaweed. Identification and quantification of dimethyl-$\beta$-propiothetin were measured by headspace gas chromatography after conversion to dimethyl sulfide by treatment with saturated NaOH solution. Dimethyl-$\beta$-propiothetin was extracted through various processes(solvent extraction, ultrasonication, boiling and autoclaving) from Enteromorpha intesinalis. The content of dimethyl-$\beta$-propiothetin extracted by autoclaving treatment showed higher than those of various extraction methods. Dimethyl-$\beta$-propiothetin content in extract of Enteromorpha Enteromorpha was 311,200ng/g after autoclaving at 121$^{\circ}C$ for 60min. Dimethyl-$\beta$-propiothetin in extract of Enteromorpha intestinalis was comparatively stable under low temperature. The retentions of dimethyl-$\beta$-propiothetin content in extract of Enteromorpha intestinalis were 75.8 ~99.8% by incubation at 10~6$0^{\circ}C$ for 2 hours. Chemical decomposition of dimethyl-$\beta$-propiothetin was observed under laboratory conditions at pH values higher than 9.5.

• ALGAE
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• v.30 no.2
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• pp.121-137
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• 2015

Studies on carbon flux in the oceans have been highlighted in recent years due to increasing awareness about climate change, but the coastal ecosystem remains one of the unexplored fields in this regard. In this study, the dynamics of carbon flux in a vegetative coastal ecosystem were examined by an evaluation of net and gross ecosystem production (NEP and GEP) and $CO_2$ exchange rates (net ecosystem exchange, NEE). To estimate NEP and GEP, community production and respiration were measured along different habitat types (eelgrass and macroalgal beds, shallow and deep sedimentary, and deep rocky shore) at Gwangyang Bay, Korea from 20 June to 20 July 2007. Vegetative areas showed significantly higher ecosystem production than the other habitat types. Specifically, eelgrass beds had the highest daily GEP ($6.97{\pm}0.02g\;C\;m^{-2}\;d^{-1}$), with a large amount of biomass and high productivity of eelgrass, whereas the outer macroalgal vegetation had the lowest GEP ($0.97{\pm}0.04g\;C\;m^{-2}\;d^{-1}$). In addition, macroalgal vegetation showed the highest daily NEP ($3.31{\pm}0.45g\;C\;m^{-2}\;d^{-1}$) due to its highest P : R ratio (2.33). Furthermore, the eelgrass beds acted as a $CO_2$ sink through the air-seawater interface according to NEE data, with a carbon sink rate of $0.63mg\;C\;m^{-2}\;d^{-1}$. Overall, ecosystem production was found to be extremely high in the vegetated systems (eelgrass and macroalgal beds), which occupy a relatively small area compared to the unvegetated systems according to our conceptual diagram of a carbon-flux box model. These results indicate that the vegetative ecosystems showed significantly high capturing efficiency of inorganic carbon through coastal primary production.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.46 no.5
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• pp.607-618
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• 2013

Marine macroalgal community structures and characteristics of ocean environmental factors were examined seasonally at four sites in Jeju Island, Korea, from March to November 2012. A total of 71 macroalgal species were identified, including 9 green, 7 brown, and 55 red algae. Peyssonnelia capensis occurred at all study sites and in all seasons. The average annual biomass of seaweed was 991.84 g wet $wt/m^2$, with seasonal variations from 543.80 g in autumn to 1,284.17 $g/m^2$ in summer. A green alga, Codium coactum, was the dominant species, occupying 21.31% (211.39 $g/m^2$) of the total algal biomass in Jeju Island. Subdominant species were Ecklonia cava and Lithophyllum okamurae, comprising 20.85% (206.75 $g/m^2$) and 19.64% (194.75 $g/m^2$), respectively, of the total algal biomass in Jeju Island. The vertical distribution of subtidal seaweeds was represented by L. okamurae at 5 m depth, C. coactum at 10 m depth, E. cava at 5-10 m depth and P. capensis at the 20 m depth level. In the present study, crustose coralline algae, which predominated on barren ground, were subdominant species at all study sites. Community indices varied between 0.51-0.63 for dominance index (DI), 5.53-8.14 for richness index (R), 0.51-0.63 for evenness index (J'), and 2.04-2.32 for diversity index (H'). On the basis of seaweed biomass and community indices, Sinchang was the best preserved coastal area, showing maximal values in biomass, and evenness- and diversity-indices, and minimal value in the dominance index, representing stable environmental conditions. In contrast, the Onpyung and Topyeong sites, located near tourist venues such as Udo and Seogwipo were relatively poor habitats based on community indices and biomass. The present results could imply that climate changes alter seaweed community structure, and long-term monitoring of the study sites is required.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.11 no.2
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• pp.85-90
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• 1978

In present study, the effect of various factors including the solvent concentration, extraction time, extraction temperature and the ratio of sample vs extraction solvent(w/v) upon the extractability of the NaOH soluble proteins of marine algae were investigated. Seven species of sun-dried algae, the major ones in consumption as food, namely Porphyra suborbiculata, Undaria pinnatifida(natural and cultivated), Sargassum fulvellum, Sargassum kjellmanianum, Ulva pertusa, Enteromorpha linza and Codium coarctatum were used for the extraction of the NaOH soluble protein. The frozen and masceratd samples were prepared by the same mettled described in previous paper(Lee, 1977). In case of the TCA insoluble protein, all samples reached maxima at 0.025M NaOH solution while the 0.05M for extractable total nitrogen. Variation of the ratio of sample vs solvent gave slight effect upon the extractability, 100 ml solvent added to 1 g dried sample was effective. The effect of extraction time on the extractability differed from species. The extractabilty of Enteromorpha linza, Ulva pertusa and Codium coarctatum reached maxima within 1 hour extraction and 2 hours for the cultivated Undaria pinnatifida while 3 flours for the natural Undaria pinnatifida, Sargassum fulvellum, Sargassum kjellmanianum and Porphyra suborbiculata. The most effective extraction temperature was $60^{\circ}C$ for all samples.

• Journal of Life Science
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• v.25 no.12
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• pp.1339-1346
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• 2015

The aim of this study is to increase production of carotenoids in recombinant Escherichia coli by Archaea chaperonin. The carotenoids are a widely distributed class of structurally and functionally diverse yellow, orange, and red natural pigments. These pigments are synthesized in bacteria, algae, fungi, and plants, and have been widely used as a feed supplement from poultry rearing to aquaculture. Carotenoids also exhibit diverse biological properties, such as strong antioxidant and antitumor activities, and enhancement of immune responses. In the microbial world, carotenoids are present in both anoxygenic and oxygenic photosynthetic bacteria and algae and in many fungi. We have previously reported cloning and functional analysis of the carotenoid biosynthesis genes from Paracoccus haeundaensis. The carotenogenic gene cluster involved in astaxanthin production contained seven carotenogenic genes (crtE, crtB, crtI, crtY, crtZ, crtW and crtX genes) and recombinant Escherichia coli harboring seven carotenogenic genes from Paracoccus haeundaensis produced 400 μg/g dry cell weight (DCW) of astaxanthin. In order to increase production of astaxanthin, we have co-expressed chaperone genes (ApCpnA and ApCpnB) in recombinant Escherichia coli harboring the astaxanthin biosynthesis genes. This engineered Escherichia coli strain containing both chaperone gene and astaxanthin biosynthesis gene cluster produced 890 μg/g DCW of astaxanthin, resulting 2-fold increased production of astaxanthin.

• Proceedings of the Korean Quaternary Association Conference
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• 2004.11a
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• pp.75-76
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• 2004

일산 이산포 BH-4 발굴단면의 퇴적물 시료로부터 화분 포자 및 담수성과 해양성조류화석이 다양하고 풍부하게 산출되었다. 산출된 식물기원 미화석 중, 목본화분 $25{\sim}60%$, 초본화분 $15{\sim}70%$ 그리고 포자 $4{\sim}30%$ 각각 구성 되었다. 또한 담수성 조류(freshwater algae)는 전체 단면구간에서 산출된 반면, 와편모류(dinoflagellate), 아크리타치(acritarch)와 같은 해양성조류(marine algae)는 하부단면구간(절대고도: 3.31-2.74 m)에서만 산출되었다. 산출된 화분 포자 및 통계처리기법(CONISS)을 이용하여 2개의 지역화분대 (local pollen a assemblage zone) 및 4개의 아화분대(local pollen assemblage subzone)가 설정되었다. 제I화분대(시료 $Al-2{\sim}A6-1$, 고도 $2.70{\sim}3.31\;m$)는 다시 제Ia아화분대(시료 $Al-2{\sim}A3-1$, 고도 $2.70{\sim}3.00\;m$)와 제Ib아화분대(시료 $A4-2{\sim}A6-1$, 고도 $3.01{\sim}3.31\;m$)로 세분되었으며; 제II화분대(시료 $A7-2{\sim}A10-1$, 고도 $3.32{\sim}3.72\;m$) 역시 두개의 아화분대인 제IIa(시료 $A7-2{\sim}A8-1$, 고도 $3.32{\sim}3.51\;m$)와 제lIb(시료 $A9-2{\sim}A10-1$, 고도 $3.53{\sim}3.72\;m$)로 이루어졌다. 화분군집조성에 의하면, 미화석들이 퇴적되었던 시기동안에 2개의 산림(forest)형태가 발달했던 나타났다. 제I화분대(고도, $3.31{\sim}2.74\;m$)의 시기동안에는 침엽수와 낙엽활엽수로 이루어진 혼합림으로, 주요 식생은 2엽소나 무(Diploxylon), 가문비((Picea), 낙엽송(Larix)의 침엽수와 참나무(Quercus), 자작나무(Betula), 개암나무(Corylus), 중국굴피 나무속(Pterocarya)의 낙엽활엽수 등이 산악-구릉지에서 주로 서식하였던 것으로 나타났다. 또한 습생나무인 오리나무(Alnus), 버드나무(Salix)등과 해안가 등지에서 잘 서식하는 양치식물과 사초과(Cyperaceae), 명아주과(Chenopodiaceae) 같은 풀들이 하구언(estuary)의 해안가에 주로 서식하였던 것으로 나타났다. 이 시기동안에 해양성조류인 와편모류와 담수성 조류가 동시에 다양하게 산출되는 것은 하구언 퇴적환경이었음을 잘 지시해 준다. 제II화분대(고도, 43.72{\sim}3.36\;m$)가 시작되면서 혼합림은 침엽수림으로 바뀌었으며, 낙엽활엽수들의 서식지가 2엽소나무로 대치되면서 침엽수가 주요 수종을 이루었던 것으로 나타났다. 아마도 이런 산림형태는 자연 기후환경변화 뿐만 아니라 인간간섭에 의해 나타난 결과로 생각된다. 이 시기에 경작식물인 벼과(Gramineae), 옥수수(Zea), 메밀(Fagopyrum)과 논밭의 뚝 등지 에서 서식하는 돼지풀(Ambrosia) 등이 처음으로 산출되는 것으로 보아 인간간섭이 행해졌음을 잘 뒷 받침해준다. 또한 담수성 조류는 변함없이 산출되는 반면, 해양성조류인 와편모류가 산출되지 않는 것으로 보아 해안환경에서 다소 멀 어진 저지대의 습윤한 충적대지환경으로 변하였던 것으로 판단된다.

• ALGAE
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• v.34 no.2
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• pp.111-126
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• 2019

The phototrophic dinoflagellate Biecheleriopsis adriatica is a small suessioid species characterized by a fragile thin wall. Although the morphology of this dinoflagellate is well established, there is currently little information available on its distribution and the environmental factors that influence this distribution. Thus, to investigate the spatial and seasonal distributions of the vegetative cells of B. adriatica in Korean waters, surface water samples were collected on a seasonal basis from 28 stations in the East, West, and South Sea of Korea and Jeju Island from April 2015 to October 2018, and abundances of the vegetative cells of B. adriatica were quantified using quantitative real-time polymerase chain reactions, for which we developed the species-specific primer and probe set. Simultaneously, major environmental parameters, including temperature, salinity, nutrient concentrations, and dissolved oxygen concentrations were measured. The vegetative cells of B. adriatica were detected at 20 of the 28 sampling stations: 19 stations in summer and 6 in autumn, although from no stations in either spring or winter. The ranges of water temperature and salinity at sites where this species was detected were $17.7-26.4^{\circ}C$ and 9.9-34.3, respectively, whereas those of nitrate and phosphate concentrations were not detectable-96.2 and $0.18-2.66{\mu}M$, respectively. Thus, the sites at which this species is found are characterized by a narrow range of temperature, but wide ranges of salinity and concentrations of nitrate and phosphate. The highest abundance of the vegetative cells of B. adriatica was $41.7cells\;mL^{-1}$, which was recorded in Jinhae Bay in July 2018. In Jinhae Bay, the abundance of vegetative cells was significantly positively correlated with the concentration of nitrate, but was negatively correlated with salinity. On the basis of these findings, it appears that the abundance of B. adriatica vegetative cells shows strong seasonality, and in Jinhae Bay, could be affected by the concentrations of nitrate.

• 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.

• Journal of Life Science
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• v.33 no.9
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• pp.703-712
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• 2023

Angiogenesis, the formation of blood vessels from pre-existing vessels, is a multistep process regulated by modulators of angiogenesis. It is essential for various physiological processes, such as embryonic development, chronic inflammation, and wound repair. Dysregulation of angiogenesis causes many diseases, such as cancer, autoimmune diseases, rheumatoid arthritis, cardiovascular disease, and delayed wound healing. However, the number of effective anti-angiogenic drugs is limited. Recent research has focused on identifying potential drug candidates from natural sources. For example, marine natural products have been shown to have anti-cancer, anti-oxidant, anti-inflammatory, antiviral, and wound-healing effects. Thus, this study aimed to describe the angiogenesis inhibitory effect of Hizikia fusiforms (brown algae) extract. The hexane extract of H. fusiformis has shown inhibitory effects on in vitro angiogenesis assays, such as cell migration, invasion, and tube formation in human umbilical vein endothelial cells (HUVECs). The hexane extract of H. fusiformis (HFH) inhibited in vivo angiogenesis in a mouse Matrigel gel plug assay. In addition, the protein expression of vascular endothelial growth factor (VEGF), mitogen-activated protein kinase (MAPK)/extracellular signal kinase, and AKT serine/threonine kinase 1 decreased following treatment with H. fusiformis extracts. Our results demonstrated that the hexane extract of H. fusiformis (HFH) inhibits angiogenesis in vitro and in vivo.

• Korean Journal of Ecology and Environment
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• v.55 no.2
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• pp.99-110
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• 2022

We investigated physicochemical properties and isotopic compositions of organic matter (δ¹³C_TOC and δ ¹⁵N_TN) in the old fish farming (OFF) site after the cessation of aquaculture farming. Based on this approach, our objective is to determine the organic matter origin and their relative contributions preserved at sediments of fish farming. Temporal and spatial distribution of particulate and sinking organic matter(OFF sites: 2.0 to 3.3 mg L^-1 for particulate matter concentration, 18.8 to 246.6 g m^-2 day^-1 for sinking organic matter rate, control sites: 2.0 to 3.5 mg L^-1 for particulate matter concentration, 25.5 to 129.4 g m^-2 day^-1 for sinking organic matter rate) between both sites showed significant difference along seasonal precipitations. In contrast to variations of δ¹³C_TOC and δ¹⁵N_TN values at water columns, these isotopic compositions (OFF sites: -21.5‰ to -20.4‰ for δ¹³ C_TOC, 6.0‰ to 7.6‰ for δ¹⁵N_TN, control sites: -21.6‰ to -21.0‰ for δ¹³C_TOC, 6.6‰ to 8.0‰ for δ¹⁵N_TN) investigated at sediments have distinctive isotopic patterns(p<0.05) for seawater-derived nitrogen sources, indicating the increased input of aquaculture-derived sources (e.g., fish fecal). With respect to past fish farming activities, representative sources(e.g., fish fecal and algae) between both sites showed significant difference (p<0.05), confirming predominant contribution (55.9±4.6%) of fish fecal within OFF sites. Thus, our results may determine specific controlling factor for sustainable use of fish farming sites by estimating the discriminative contributions of organic matter between both sites.