• Journal of the Korean Society for Marine Environment & Energy
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• v.16 no.1
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• pp.25-35
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• 2013

Dominance and survival strategy of toxic dinoflagellate Alexandrium tamarense and A. catenella under the dissolved inorganic nitrogen (DIN) limited conditions were examined in the laboratory and field observations. In Masan Bay, DIN was limiting factor for growth of phytoplankton during spring to early summer when Alexandrium spp. have been observed. They have a disadvantageous position compared with diatoms because Ks of nitrate calculated from growth kinetics experiment of A. tamarense and A. catenella was higher than diatoms. However, A. tamarense and A. catenella were able to grow using dissolved organic nitrogen (DON) compounds such as urea and amino acids as well as DIN. Therefore, DON utilization of A. tamarense, A. catenella might contribute to not only their population growth but also dominance and interspecific competition in the DIN-limited conditions in Masan Bay.

• Journal of Life Science
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• v.14 no.2
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• pp.301-308
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• 2004

The morphology of the apical pore complex, the first apical plate and the posterior sulcal plates in a new isolate of Alexandrium tamarense (Lebour) Balech from the Bay of Chinhae was compared with other that of toxic strains of A. tamarense previously isolated from Korean waters. Although this isolate was morphologically identical to these toxic strains, high performance liquid chromatography and mouse bioassay showed no evidence of toxin production. The nontoxic A. tamarense strain showed a strong positive binding activity with PNA lectin, indicating a high density of lactose and galactose residues on the cell surface, and in SDS-PAGE and Western blot analysis a unique protein of about 21-kDa molecular sizes was observed. These findings demonstrate that the use of PNA and immunobioassay could be used to discriminate between toxic and nontoxic strains of A. tamarense.

• Journal of Environmental Science International
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• v.22 no.12
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• pp.1571-1577
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• 2013

The effects of irradiance on the growth of toxic dinoflagellates Alexandrium tamarense (Masan Bay strain) and Alexandrium catenella (Jinhae Bay strain) were investigated in the laboratory. At $15^{\circ}C$ and 30 psu for A. tamarense and $25^{\circ}C$ and 30 psu for A. catenella, the irradiance-growth curve showed the maximum growth rate (${\mu}_{max}$) of 0.31 $day^{-1}$ with half-saturation photon flux density (PFD) ($K_I$) of 44.53 ${\mu}molm^{-2}s^{-1}$, and a compensation PFD ($I_c$) was 20.67 ${\mu}molm^{-2}s^{-1}$ for A. tamarense, and ${\mu}_{max}$ of 0.38 $day^{-1}$ with $K_I$ of 59.53 ${\mu}molm^{-2}s^{-1}$, and $I_c$ was 40.80 ${\mu}molm^{-2}s^{-1}$ for A. catenella. The $I_c$ equated to a depth of 8~9 m from March to June for A. tamarense and 6~7 m from March to June for A. catenella. These responses suggested that irradiance at the depth near the middle layer in Masan Bay would provide favorable conditions for two species.

• Journal of Life Science
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• v.12 no.3
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• pp.250-255
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• 2002

Fluorescent species-specific DNA probe (AT1) of toxic dinoflagellate Arexandrium tamarense was tested on several other species, on comparison of binding activity at different preservatives for fixation of the cells, at different culture age and estimation of cell density by light microscope or epifluorescent microscope using whole cell hybridization. Th AT1 probe specifically bound to Alexandrium tamarense, whereas it did not bind to other phytoplankton, in particular Alexandrium catenella, morphologically similar to Alexandrium tamarense, could not react to AT1 probe. When cells were fixed with all three preservatives, labeling cells of Alexandrium tamarense emitted strong fluorescent signal intensity. In addition, regardless culture days, binding activity with AT1 probe was strong. The tell densities estimated by epifluorescent microscope were than those estimated by light microscope. The enumeration and identifying of Arexandriurn tamarense using DNA probe method will be contributed to a new biotoxin monitoring and prediction system in field.

• Journal of the korean society of oceanography
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• v.39 no.3
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• pp.163-171
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• 2004

Sequences of the large subunit ribosomal (LSD) rDNA D1-D2 region of Alexandrium catenella(=A. sp. cf. catenella) and A. tamarense isolates, which were collected along the Korea coasts, were analyzed to understand their phylogenetic relationships and geographical distributions. All A. catenella and A. tamarense isolates belonged to the A. tamarense/catenella/fundyense complex and were grouped with the North American and temperate Asian ribotypes, respectively, regardless of the presence or absence of a ventral pore in the first apical plate. A consistent and peculiar characteristic that differentiated the Alexandrium isolates was amplification of a second PCR product with a lower molecular weight in addition to the predicted one; ten A. catenella isolates belonging to the temperate Asian ribotype yielded this additional PCR product. Sequence alignment revealed that the shorter PCR product resulted from an unusual large deletion of 87 bp in the LSD rDNA D1 domain. The North American and temperate Asian ribotypes were prevalent along the Korean coasts without geographical separation. Given the high genetic homogeneity among widely distributed Alexandrium populations, each ribotype appeared to be pandemic rather than to constitute a distinct regional population.

• Ocean Science Journal
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• v.40 no.3
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• pp.155-166
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• 2005

New PCR primers (N=18) were designed for the isolation of complete SSU to LSU rDNA sequences from the dinoflagellate Alexandrium tamarense. Standard PCR, employing each primer set selected for amplifications of less than 1.5 kb, successfully amplified the expected rDNA regions of A. tamarense (Korean isolate, HY970328M). Complete SSU, LSU rDNAs and ITS sequences, including 5.8S rDNA, were recorded at 1,800 bp, 520 bp and 3,393 bp, respectively. The LSU rDNA sequence was the first report in Alexandrium genus. No intron was found in the LSU rRNA coding region. Twelve D-domains within the LSU rDNA were put together into 1,879 bp (44.4% G+C), and cores into 1514 bp (42.8% G+C). The core sequence was significantly different (0.0867 of genetic distance, 91% sequence similarity) in comparison with Prorocentrum micans (GenBank access. no. X16108). The D2 region was the longest in length (300 bp) and highly variable among the 12 D-domains. In a phylogenetic analysis using complete LSU rDNA sequences of a variety of phytoplankton, A. tamarense was clearly separated with high resolution against other species. The result suggests that the sequence may resolve the taxonomic ambiguities of Alexandrium genus, particularly of the tamarensis complex.

• Korean Journal of Environmental Biology
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• v.22 no.1
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• pp.200-205
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• 2004

The effects of environmental eonditions on germination of Alexandrium tamarense cysts were examined. The cysts were isolated from the sediment samples collected from Masan Bay. Germination success was measured by the incubation of cysts under the laboratory conditions and compared in different water temperatures, salinities, and sediment depths. The highest germination rate was recorded at $15^{\circ}C$ and relatively higher germination rate was observed at $10^{\circ}C$ above, while little or no germination occurred at 20 to $25^{\circ}C$. Light and salinity affected little on the excystment. Germination rate according to the sediment depths was higher in the lower layer (5∼10 cm) than in the upper (0∼2 cm) of the sediments collected in March, while higher in the upper than the lower in November. :Based on these results, water temperature seems a principal factor controlling germination of A. tamarense in Masan Bay.

• Ocean and Polar Research
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• v.25 no.4
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• pp.625-631
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• 2003

While phytoplankton diversity and productivity in the Southern Ocean has been widely studied in recent years, most attention has been given to elucidating environmental factors that affect the dynamics of micro-plankton (mainly diatoms) and nano-plankton (mainly Phaeocystis antarctica). Only limited effects have been given to studying the occurrence and the potential risks associated with the blooming of dinoflagellates in the relevant waters. This study focused on the appearance and toxicological characteristics of a toxic dinoflagellate, Alexandrium tamarense, identified and isolated from the Drake Passage in a research cruise from November to December 2001 The appearance of A. tamarense in the Southern Ocean indicates the risk of a paralytic shellfish poisoning (PSP) outbreak there and is therefore of scientific concern. Results showed that while the overall quantity of A. tamarense in water samples from 30meters below the sea surface often comprised less than 0.1% of the total population of phytoplankton, the highest concentration of A. tamarense (20 cells $L^{-1}$) was recorded in the portion of the Southern Ocean between the southern end of South America and the Falkland Islands. Waters near the Polar Front contained the second highest concentrations of 10-15 cells $L^{-1}$. A. tamarense was however rarely found in waters near the southern side of the Polar Front, indicating that cold sea temperatures near the Antarctic ice does not favor the growth of this dinoflagellate. One strain of A. tamarense from this cruise was isolated and cultured for further study in the laboratory. Experiments showed that this strain of A. tamarense has a high tolerance to temperature variations and could survive at temperatures ranging from $5-26^{\circ}C$. This shows the cosmopolitan nature off. tamarense. With regard to the algal toxins produced, this strain of A. tamarense produced mainly C-2 toxins but very little saxitoxin and gonyailtoxin. The toxicological property of this A. tamarense strain coincided with a massive death of penguins in the Falkland Islands in December 2002 to January 2003.

• Korean Journal of Environmental Biology
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• v.24 no.3
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• pp.275-281
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• 2006

We examined effects of water temperature, salinity, irradiance, and different media on the growth of the toxic dinoflagellate Alexandrium tamarense (HYM9704), which was isolated from Jinhae Bay, Korea. The ranges of temperature and salinity in which the strain was able to grow were $10{\sim}20^{\circ}C$ and $20{\sim}34$ psu, respectively. These values were in accordance with those observed in situ. The maximum growth rates of axenic A. tamarense (HYM9704) was $0.25d^{-1}$ at $15^{\circ}C$, 30 psu, and $100{\mu}Em^{-2}s^{-1}$. The temperature affected the growth rates of axenic A. tamarense more significantly than the salinity. The type of culture media did not affect the growth rates of axenic A. tamarense. The strain in N-limited and P-limited media went into the stationary phase faster than that in T1 and T1/2 medium.

• ALGAE
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• v.23 no.4
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• pp.251-255
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• 2008

In Gamak Bay, Paralytic Shellfish Poisoning (PSP) was first detected from seafoods in 2003, however the toxin source is unknown yet. In this study, we report potential PSP producers of toxic dinoflagellates, describing morphology and abundance of cysts isolated from surface sediment of Gamak Bay. The most abundant type in these cysts was characterized with ellipsoidal and transparent wall identical to Alexandrium catenella and/or A. tamarense. Germination experiment of the cysts revealed that all motile cells germinated were morphologically identified as A. tamarense. This result suggests that A. tamarense may relate to PSP contaminations in Gamak Bay. Moreover, bottom water temperature in Gamak Bay is favorable for germination of A. tamarense cysts. Further studies are required to carry out the PSP monitoring for preventing the risk of PSP events that may outbreak in future at Gamak Bay.