• Ocean and Polar Research
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• 제33권2호
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• pp.99-111
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• 2011

To estimate the effects of limitation nutrients for phytoplankton growth and its influences on short-term variations of a winter phytoplankton community structure, we investigated the abiotic and biotic factors of surface and bottom waters at 20 stations of inner and offshore areas from 6 to 7 February in Gwangyang Bay, Korea. Also, several algal bio-assay studies were conducted to identify any additional nutrient effects on phytoplankton assemblage using surface water for the assay. The dominant species in the bay was diatom Skeletonema costatum, which occupied more than 70% of total species in most stations (St.1-16) of the inner bay. According to a cluster and multidimensional scaling (MDS) analysis based on phytoplankton community data from each station, the bay was divided into three groups. The first group included stations from the south-western parts of Myodo lsland, which can be characterized as a semien-closed eutrophic area with high phytoplankton abundance. The second group included most stations from the north-eastern part of Myodo lsland, influenced indirectly by surface water currents from offshore of the bay. The standing phytoplankton crops were lower than those of the first group. The other cluster was restricted to samples collected from offshore of the bay. In the bay, silicon (Si) and phosphorus (P) were not a major limiting factor for phytoplankton production. However, since the DIN: DIP and DSi: DIN ratios clearly demonstrated that there were potential stoichiometric N limitations, nitrogen (N) was considered as a limiting factor. Based on the algal bio-assay, in vivo fluorescence values in N (+) added experiments were higher compared to control and P added experiments. Our results suggested that nitrogen may act as one of the most important factors in controlling primary production during winter in Gwangyang Bay.

• 한국양식학회지
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• 제19권1호
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• pp.33-39
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• 2006

Anticoagulant activities of a fermented edible brown alga, Laminaria ochotensis was investigated. L. ochotensis was fermented with 15% sugar (w/v) at $25^{\circ}C$ for 10 weeks. Anticoagulant activity was measured from the supernatant of algal mixture at biweekly intervals up to $10^{th}$ week by activated partial thromboplastin (APTT), prothrombin time (PT) and thrombin time (TT) assay using citrated human plasma. Sample having high APTT activity $(6^{th}\;week)$ was filtered, ethanol precipitated and freeze-dried. The polysaccharide compound having anticoagulant activity was purified by DEAE ion exchange chromatography followed by Sepharose-4B gel filtration chromatography. Anticoagulant activity, polysaccharide concentration, and heparin like activity were determined for the collected fractions by APTT, $phenol-H_2SO_4$, and glycosaminoglycan assay, respectively. The anticoagulant activity assay showed that the activity was increased up to $6^{th}$ week, and decreased thereafter. The concentration of our purified compound was $31.0{\mu}g/ml$ and showed higher APTT activity than commercial heparin. At the same concentration of $31.0{\mu}g/ml$, the heparin showed 186.5 sec activity while our purified compound showed an activity of 386 sec. Single spot on agarose gel electrophoresis showed that the compound was purified and polyacrylamide gel electrophoresis (PAGE) results revealed that the molecular mass of the purified polysaccharide compound was between 60 and 500 kDa. Therapeutic interest of the algal polysaccharide as an anticoagulant has recently been in highlighted. This purified anticoagulant compound from fermented L. ochotensis can be used as a model for anticoagulant agent or could be developed as an anticoagulant agent. This study can be extended to identify the structure and chemical composition of the purified polysaccharide, and to establish a relationship between structure and the function of the identified anticoagulant compounds.

• 한국환경과학회지
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• 제4권5호
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• pp.83-83
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• 1995

The increase of population and industrial activities had brought into eutrophication in the Nakdong river. A remarkable acceleration of eutrophication brought about serious problems for water supply. Therefore, for the purpose of conservation of water quality in the Nakdong river it is necessary to control nutrients. MBOD method was use to evaluate algal growth limiting factor and algal growth potential in the Nakdong river from June to August 1994. The modified biochemical oxygen demand(MBOD) depends on the amount of available inorganic nutrient and organic substrate during 5 day incubation in the dark at 20$^{circ}C$. The MBOD assay depends on inorganic nutrients such as P and N as well as reduced carbon and called the MBOD, the MBOD-P, and the MBOD-N, respectively. The results of bioassay by MBOD(Modified BOD) method showed that the MBOD, MBOD-P and MBOD-N value were found to be in the ranges of 3.8∼96.0 mg$O_2$/l, 5.6∼94.0 mg$O_2$/l and 42.0∼220 mg$O_2$/l, respectively. And the the bioassay value was found to be the highest in Koryong area and the lowest in Waekwan area throughout the Nakdong river. The variations of MBOD-P and MBOD-N value showed similar tendencies to the variations of phosphorus and nitrogen value, respectively. By MBOD method, the relationships of MBOD, MBOD-P and MBOD-N value were MBOD ≒ MBOD-P 《 MBOD-N. The MBOD value was nearly equal to the MBOD-P value, and the MBOD-N value was 3 to 20 times more than the MBOD-P value, approximately. Therefore, in the Nakdong river, phosphorus was the limiting factor for algal growth during summer season. The algal growth potential as the concentration of chlorophyll-a in the summer was maximum 5 times more than standing crop as it.

• Fisheries and Aquatic Sciences
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• 제7권3호
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• pp.122-129
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• 2004

Harmful Cochlodinium polykrikoides is a notorious harmful algal bloom (HAB) species that is causing mass mortality of farmed fish along the Korean coast with increasing frequency. We analyzed the sequence of the large subunit (LSD) rDNA D1-D3 region of C. polykrikoides and conducted phylogenetic analyses using Bayesian inference of phylogeny and the maximum likelihood method. The molecular phylogeny showed that C. polykrikoides had the genetic relationship to Amphidinium and Gymnodinium species supported only by the relatively high posterior probabilities of Bayesian inference. Based on the LSU rDNA sequence data of diverse dinoflagellate taxa, we designed the C. polykrikoides-specific PCR primer set, CPOLY01 and CPOLY02 and developed PCR detection assays for its sensitive, accurate HAB monitoring. CPOLY01 and CPOLY02 specifically amplified C. polykrikoides and did not cross-react with any dinoflagellates tested in this study or environmental water samples. The effective annealing temperature $(T_{p})$ of CPOLY01 and CPOLY02 was $67^{\circ}C$. At this temperature, the conventional and nested PCR assays were sensitive over a wide range of C. polykrikoides cell numbers with detection limits of 0.05 and 0.0001 cells/reaction, respectively.

• Fisheries and Aquatic Sciences
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• 제8권4호
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• pp.243-246
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• 2005

The addition of seaweed extracts was found to regulate the viability of cultures of the crustose coralline alga Lithophyllum yessoense. The viability was quantitated using a triphenyltetrazolium chloride assay, and the methanol-soluble extracts from 18 prevalent seaweed species were tested. Extracts from Codium fragile and Enteromorpha linza inhibited viability, and a Hizikia fusiform is extract slightly increased viability. The methanol extract of C. fragile, which had the strongest inhibitory activity, decreased viability to 72 or $52\%$ that of the control following addition of 0.2 or 2 mg/mL of extract to the culture, respectively. The main active compound in the C. fragile was lipid. This information is a preliminary result related to the exploration of seaweed restoration in the algal whitening area.

• 해양환경안전학회지
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• 제12권2호
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• pp.81-87
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• 2006

본 연구는 남해안 북만 해역을 대상으로 조류성장잠재력(AGP) 시험을 통하여 H. akashiwo의 성장제한요인을 평가하였다. 영양물질의 첨가 및 미생물과의 동시배양에 의하면 적조발생 단계별 H. akashiwo의 성장은 서로 다른 제한요인에 의하여 영향을 받는 것으로 나타났다. 적조발생 전의 H. akashiwo 성장은 질산질소 $50{\mu}M$과 연산인 $5{\mu}M$을 복합첨가하면 크게 증가하였지만 인산인을 단독 첨가하거나 미생물과 동시 배양하여도 전혀 영향이 없었다. 적조발생 전의 H. akashiwo 성장제한요인은 질산질소로 나타났다. 적조발생시기의 H. akashiwo 성장은 질산질소 $50{\mu}M$ 또는 인산인 $5{\mu}M$을 단독첨가하면 증가하였지만 미량영양물질이나 $vitamin\;B_{12}$을 첨가해도 전혀 영향이 없었다. 적조발생 시기의 H. akashiwo 성장제한요인은 질산질소와 인산인이 동시에 작용하는 것으로 나타났다. 반면에 적조소멸시기의 H. akashiwo 성장은 질산질소와 인산인을 첨가하면 약간 증가하였지만 미생물과 동시 배양하면 현저히 감소하였다. 그러므로 적조 소멸시기의 H. akashiwo 성장제한은 미생물요인에 의한 것으로 평가되었다.

• 생명과학회지
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• 제30권1호
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• pp.26-31
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• 2020

Heterosigma akashiwo는 전세계적으로 분포된 침편모조류이며, 대발생을 형성하여 많은 나라의 양식산업에 커다란 손실을 유발시킨다. 따라서 빠르고 민감한 검출방법을 개발하는 것은 유해조류 대발생에 대한 적절한 경보를 위해서 필요하다. 이 연구에서는 H. akashiwo를 정성 및 정량적으로 검출하기 위하여 뉴클레아제 보호 분석이 통합된 샌드위치 혼성(NPA-SH)을 개발하였다. NPA-SH 프로브는 여섯 종의 미세조류 핵산 서열을 이용하여 디자인 후, 특이성을 확인하여 capture 프로브와 signal 프로브를 선정하였다. 배양시료와 현장시료를 이용하여 NPA-SH의 적용성을 평가한 결과, NPA-SH의 좋은 적용성과 효과를 확인하였다. H.akashiwo의 정량분석을 위한 선형회귀식을 확인하였으며, 최소 검출한계는 1×10⁴ cells/ml이었다. NPA-SH를 사용하여 얻은 H. akashiwo의 정량결과와 현미경을 사용하여 얻은 결과 사이에는 통계학적으로 유의한 차이는 없었다. NPA-SH 분석은 환경시료에 잘 적용되었다. 이러한 결과는 NPA-SH가 H. akashiwo의 모니터링에 사용되어 왔던 전통적인 현미경적 방법에 대한 좋은 대안이 될 수 있음을 보여준다.

• 한국산학기술학회논문지
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• 제20권8호
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• pp.627-633
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• 2019

유해조류 대발생(harmful algal blooms, HABs)을 유발하는 해양 미세조류의 신속하고 정확한 종판별은 HABs을 예측하고 관리하기 위한 매우 중요한 도구이다. 우리는 이전 연구에서 적조 유발 미세조류인 Cochlodinium polykrikoides를 현장에서 검출하기 위한 nuclease protection assay sandwich hybridization (NPA-SH) 방법을 개발한 바 있다. 본 연구에서는 C. polykrikoides 검출을 위한 NPA-SH 방법의 반응 단계를 간소화시켜 현장 적용성을 향상시키는 것을 목적으로, signal probe에 형광 대신 invertase (INV)를 결합시켰으며, hybridization 과정에서 sucrose를 반응물로 사용하여 발색 반응을 유도하였다. INV와 signal probe의 결합 여부는 SDS-PAGE와 형광 현미경을 사용하여 확인하였으며, 반응 최적화를 위한 적정 프로브의 양, sucrose의 양 및 처리시간 등을 정립하였다. 본 연구의 결과 개발된 INV-SH는 NPA-SH와 비교하여 현장에서의 처리시간이 감소되었으며, 흡광도 측정기 뿐만 아니라, 상대적으로 부피가 작고 값 싼 개인 혈당계 사용이 가능하게 되었다. 본 연구에서 개발된 INV-SH는 INV가 적용된 최초의 C. polykrikoides 종판별 기술이며, 증진된 현장기술이 될 수 있다.

• ALGAE
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• 제37권4호
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• pp.281-291
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• 2022

Quantifying the abundance of Chattonella species is necessary to effectively manage the threats from ichthyotoxic raphidophytes, which can cause large-scale mortality of aquacultured fish in temperate waters. The identification and cell counting of Chattonella species have been conducted primarily on living cells without fixation by light microscopy because routine fixatives do not retain their morphological features. Species belonging to the Chattonella marina complex, including C. marina and C. marina var. ovata, had high genetic similarities and the lack of clear morphological delimitations between the species. To estimate the abundance of C. marina complex in marine plankton samples, we developed a protocol based on the droplet digital polymerase chain reaction (ddPCR) assay, with C. marina complex-specific primers targeting the internal transcribed spacer (ITS) region of the rDNA. Cell abundance of the C. marina complex can be determined using the ITS copy number per cell, ranging from 25 ± 1 for C. marina to 112 ± 7 for C. marina var. ovata. There were no significant differences in ITS copies estimated by the ddPCR assay between environmental DNA samples from various localities spiked with the same number of cells of culture strains. This approach can be employed to improve the monitoring efficiency of various marine protists and to support the implementation of management for harmful algal blooms, which are difficult to analyze using microscopy alone.

• Journal of Microbiology and Biotechnology
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• 제17권12호
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• pp.1922-1929
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• 2007

A simple whole-cell-based sensing system is proposed for determining the cell mass of H. pluvialis using ultraviolet fluorescence spectroscopy. An emission signal at 368 nm was used to detect the various kinds of green, green-brown, brown-red, and red H. pluvialis cells. The fluorescence emission intensities of the cells were highest at 368 nm with an excitation wavelength of 227 nm. An excitation wavelength of 227 nm was then selected for cell-mass sensing, as the emission fluorescence intensities of the cell suspensions were highest at this wavelength after subtracting the background interference. The emission fluorescence intensities of HPLC-grade water, filtered water, and HPLC-grade water containing a modified Bold's basal medium (MBBM) were measured and the difference was less than 1.6 for the selected wavelengths. Moreover, there was no difference in the emission intensity at 368 nm among suspensions of the various morphological states of the cells. A calibration curve of the fluorescence emission intensities. and cell mass was obtained with a high correlation ($R^2=0.9938$) for the various morphological forms of H. pluvialis. Accordingly, the proposed method showed no significant dependency on the various morphological cell forms, making it applicable for cell-mass measurement. A high correlation was found between the fluorescence emission intensities and the dry cell weight with a mixture of green, green-brown, brown-red, and red cells. In conclusion, the proposed model can be directly used for cell-mass sensing without any pretreatment and has potential use as a noninvasive method for the online determination of algal biomass.