• ALGAE
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• 제28권4호
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• pp.307-330
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• 2013

The genus Cryptomonas is easily recognized by having two flagella, green brownish color, and a swaying behavior. They have relatively simple morphology, and limited diagnostic characters, which present a major difficulty in differentiating between species of the genus. To understand species delineation and phylogenetic relationships among Cryptomonas species, the nuclear-encoded internal transcribed spacer 2 (ITS2), partial large subunit (LSU) and small subunit ribosomal DNA (rDNA), and chloroplast-encoded psbA and LSU rDNA sequences were determined and used for phylogenetic analyses, using Bayesian and maximum likelihood methods. In addition, nuclear-encoded ITS2 sequences were predicted to secondary structures, and were used to determine nine species and four unidentified species from 47 strains. Sequences of helix I, II, and IIIb in ITS2 secondary structure were very useful for the identification of Cryptomonas species. However, the helix IV was the most variable region across species in alignment. The phylogenetic tree showed that fourteen species were monophyletic. However, some strains of C. obovata had chloroplasts with pyrenoid while others were without pyrenoid, which used as a key character in few species. Therefore, classification systems depending solely on morphological characters are inadequate, and require the use of molecular data.

• ALGAE
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• 제21권2호
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• pp.169-174
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• 2006

We have cultured more than 100 Arctic and Antarctic cryophilic microalgal strains in KOPRI culture collections of polar microorganisms (KCCPM). Among them, we tried to identify an Antarctic strain, KOPRI AnM0008 by morphological and molecular analysis. Nuclear SSU rDNA and plastid rbcL sequences were used to identify the strain. It was identified as Porosira pseudodenticulata based on SSU sequence data showing 99% identity with GenBank X85398. This result was supported by morphological features like solitary labiate process, external foramina and internal cribra by optical and scanning electron microscope. Morphological identification and molecular analysis on polar cryophilic microalgae will be accomplished to construct the databases for KCCPM.

• ALGAE
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• 제33권3호
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• pp.243-267
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• 2018

A taxonomic study was recently carried out on species of the tribe Ceramieae (Ceramiaceae, Rhodophyta), following an evaluation of previously published records and on the basis of field and laboratory investigations. In Morocco, the tribe is represented by 5 genera: Ceramium (21 taxa at specific and infraspecific levels), Gayliella (3 species), and by one species each of Centroceras, Corallophila and Microcladia. Among these, there are five new records for Morocco: Centroceras gasparrinii, Ceramium botryocarpum, Ceramium cingulatum, Ceramium echionotum var. mediterraneum, and Gayliella taylorii. The report of C. echionotum var. mediterraneum from the Atlantic coast of Morocco is one of the rare records from outside the Mediterranean. Ceramium ciliatum var. robustum and Ceramium codii are recorded for the first time from the Atlantic coast of Morocco. Centroceras clavulatum is excluded from Moroccan flora having been misidentified for C. gasparrinii. This paper summarizes the taxonomic characters of these species with images and presents a key for their identification. This report is the first detailed record of the species of the tribe Ceramieae for Morocco. As a result, the total number of taxa at both specific and infraspecific levels accepted in the tribe Ceramieae for Morocco, under current taxonomy and nomenclature, is 27.

• ALGAE
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• 제34권1호
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• pp.57-70
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• 2019

DNA metabarcoding is currently used for large-scale taxonomic identification to understand the community composition in various marine ecosystems. However, before being widely used in this emerging field, this experimental and analytic approach still has several technical challenges to overcome, such as polymerase chain reaction (PCR) bias, and lack of well-established metabarcoding markers, a task which is difficult but not impossible to achieve. In this study, we present an adapted PCR-free small-organelles enriched metagenomics (SoEM) method for marine biodiversity assessment. To avoid PCR bias and random artefacts, we extracted target DNA sequences without PCR amplification from marine environmental samples enriched with small organelles including mitochondria and plastids because their genome sequences provide a valuable source of molecular markers for phylogenetic analysis. To experimentally enrich small organelles, we performed subcellular fractionation using modified differential centrifugation for marine environmental DNA samples. To validate our SoEM method, two marine environmental samples from the coastal waters were tested the taxonomic capturing capacity against that of traditional DNA metabarcoding method. Results showed that, regardless of taxonomic levels, at least 3-fold greater numbers of taxa were identified in our SoEM method, compared to those identified by the conventional multi-locus DNA metabarcoding method. The SoEM method is thus effective and accurate for identifying taxonomic diversity and presents a useful alternative approach for evaluating biodiversity in the marine environment.

• 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.

• ALGAE
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• 제35권3호
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• pp.277-292
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• 2020

Omega-3 fatty acids, including eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), are polyunsaturated fatty acids beneficial to human health. A limited number of microalgae have been used for commercial omega-3 production, which necessitates the identification of new microalgae with high omega-3 contents. We explored the fatty acid composition and EPA and DHA contents of the mixotrophic dinoflagellate Gymnodinium smaydae fed with the optimal algal prey species Heterocapsa rotundata. Cells of G. smaydae were found to be rich in omega-3 fatty acids. In particular, the DHA content of G. smaydae was 21 mg g^-1 dry weight, accounting for 43% of the total fatty acid content. The percentage of DHA in the total fatty acid content of G. smaydae was the highest among the reported microalgae except for Crypthecodinium cohnii. Moreover, to determine if the prey supply interval affected the growth rate of G. smaydae and its fatty acid content, three different prey supply intervals (daily, once every 2 d, and once for 4 d) were tested. Daily prey supply yielded the highest total fatty acid and DHA contents in G. smaydae. Furthermore, we successfully produced high-density G. smaydae cultures semi-continuously for 43 d with daily prey supply. During the semi-continuous cultivation period, the highest density of G. smaydae was 57,000 cells mL^-1, with an average growth rate of 0.7 d^-1. Taken together, the percentage of EPA and DHA in the total fatty acid content was maintained in the range of 54.2-56.9%. The results of this study support G. smaydae as a promising microalgal candidate for commercial DHA production and demonstrate that daily supply of prey can efficiently produce high-density G. smaydae cultures for more than a month.

• ALGAE
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• 제32권1호
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• pp.15-28
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• 2017

Morphological, molecular and chromosomal studies were carried out on Tauya basicrassa, an endemic kelp species distributed on the northern continental coast of the Sea of Okhotsk in Russia. The sporophytes of T. basicrassa grow up to 3-6 m long, 1.8-2.2 m wide, and 6.5-7 kg wet weight. The thallus has a blade with very thick narrow basal portion and thinner and much broader upper portion, which usually splits into 3 bullated lobes. A dwarf laminariacean alga, which did not show any morphological similarity to the other species of the order Laminariales, was found from the same locality. The blade of this alga is thin and soft, reached 26-34 cm long and 6-6.5 cm wide and had 4 longitudinal rows of bullations that covered the entire blade. Molecular analysis showed that the dwarf alga has 100% sequence identity in plastid-encoded RuBisCo spacer, mitochondrial cytochrome c oxidase subunit 1 and nuclear-encoded rDNA genes with normal sporophytes of T. basicrassa, indicating that they are different life forms of the same species. Fluorescent DAPI staining showed that the nucleus in the normal sporophyte was 50-65% larger than those of the dwarf ones. Chromosome count using acetocarmine staining showed n = ca. 20 for the normal sporophytes of T. basicrassa and n = ca. 10 for the dwarf one. These results suggest that the dwarf thallus is a haploid parthenosporophyte of T. basicrassa, which developed in nature. This is the first evidence of parthenosporophytes of the laminariacean algae occurring naturally in the field.

• Ocean and Polar Research
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• 제45권3호
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• pp.173-183
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• 2023

The barren ground phenomenon in Korea began to occur and spread in the southern coast region and in Jeju Island in the 1980s, and since the 1990s, the damage has become serious in the east coast region as well. Korea has enacted the fisheries resource management act to manage such barren ground through the installation of sea forests among projects for the creation of fishery resources. Until now, projects related to the identification of the cause of barren ground have focused on the density of crustose coralline algae, sea urchins and seaweed, so the original cause of barren ground has not yet been identified. In order to manage barren ground, it is necessary to identify the cause of barren ground. To identify these causes, it is necessary to comprehensively consider i) studies on spatial characteristics such as rock mass distribution, slope and water depth, ii) studies on ecological and oceanographic characteristics such as water temperature, salinity, El Niño, and typhoons etc, iii) studies on organisms such as crustose coralline algae, macroalgae, and sea urchins, and iv) studies on coastal use such as living and industrial sewage inflow. Next, as with regard to legislative policy proposals , it is necessary to prepare self-management measures by the government, local governments, and fishermen as well as address management problems related to the use of sea forests by fishermen after their creation . In addition, when creating a sea forest, a management model for each resource management plan is required, and evaluation indicators and indexes that can diagnose the cause of barren ground and guidelines for barren ground measures should be developed.

• Environmental Analysis Health and Toxicology
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• 제25권3호
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• pp.207-214
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• 2010

Toxicity identification and quantification are important factors to evaluate the effect of industrial effluent on the aquatic environment. In order to measure the potential and real toxicity of mixed chemicals in the effluents, the biological method (i.e., WET test) should be used as well as chemical analysis method. In this study, we conducted WET test for various kinds of industrial effluents using aquatic organisms such as water flea (Daphnia magna), algae (Pseudokirchneriella subcapitata), fish (Oryzias latipes, Danio rerio), and microorganism (Vibrio fisheri). In addition, we carried out chemical analysis and TIE (Toxicity Identification Evaluation) for effluents in order to identify the substances causing toxicity. Among the 30 kinds of wastewater, S13 showed the highest eco-toxicity and $Ca^{2+}$ and $Cl^-$ ion were suspected as major compounds causing toxicity for aquatic organisms. In order to confirm these suspected compounds, various confirmation procedures need to be carried out.

• 한국잡초학회지
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• 제12권4호
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• pp.352-361
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• 1992

논조류(藻類)의 생태적(生態的) 특성(特性) 및 효율적(效率的)인 방제법(防除法) 구명(究明)에 필요(必要)한 기초자료(基礎資料)를 얻기 위하여 1991년 논 또는 용배수로(用排水路) 등(等)에 많이 발생(發生)하는 윤조류(輪藻類), 이앙후(移秧後) 논물에 수화현상(水花現像)을 일으키는 유그레나류(類) 및 벼 직파재배(直播栽培) 논에서 괴불을 일이키는 규조류(硅藻類)를 동정(同定)하여 다음과 같은 결과(結果)률 얻었다. 1. 논에 발생(發生)하는 윤조류(輪藻類)로서 윤조식물문(輪藻植物門(Charophyta) 쇠뜨기말과(科)(Characeae)로 분류(分類)되는 쇠뜨기말(Chara braunii) 1종(種)이 동정(同定)되었다. 2. 논에 발생(發生)하는 유그레나류(類)에는 유그레나과(科)(Euglenaceae)로 분류(分類)되는 유그레나 2종(種), 파쿠스 1종(種), 트라케로모나스 3종(種)이 동정(同定)되었다. 3 논발생(發生) 규조식물문(硅藻植物門)(Bacillariophyta)에는 체 모양원반과(圓盤科) 5종(種), 띠돌말과(科) 3종(種), 아크난테스과(科) 1종(種), 깃돌말과(科) 9종(種), 킴벨라과(科) 1종(種), 니트찌아과(科) 2종(種) 등(等) 총(總) 6과(科) 13속(屬) 21종(種)이 동정(同定)되었다. 4. 논 수면(水面)에 나타나는 적색(赤色) 수화현상(水花現像)은 포배형성기(胞裵形成期)의 유그레나 다발생(多發生)에 기인(起因)하였다. 5. 논토양(土壤)에 발생(發生)하는 갈색(褐色) 괴불에는 우상규조목(羽狀硅藻目)에 속(屬)하는 규조류(硅藻類)가 우점(優占)하고 있었다.