• Journal of the Korean Society for Marine Environment & Energy
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• v.15 no.2
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• pp.133-141
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• 2012

Effects of temperature and salinity on the growth of the toxic dinoflagellate $Alexandrium$ $tamarense$ and $A.$ $catenella$ isolated from the southern coast of Korea were examined in the laboratory. Growth experiment was conducted under the following combinations of temperature and salinity; 10, 15, 20, 25 and $30^{\circ}C$, 10, 15, 20, 25, 30 and 35 psu at a constant irradiance of 300 ${\mu}mol$ photons $m^{-2}s^{-1}$. Temperature and salinity conditions for maximum growth rate were indicated as follows: temperature $15^{\circ}C$ and salinity 30 psu (0.31 $d^{-1}$) in $A.$ $tamarense$, temperature $25^{\circ}C$ and salinity 30 psu (0.36 $d^{-1}$) in A. catenella. Temperature and salinity ranges for optimum growth condition of two species were $10{\sim}20^{\circ}C$, 25~35 psu and $120{\sim}30^{\circ}C$, 25~35 psu, respectively. The result of two-factor ANOVA indicated significant effects (P<0.001) of temperature and salinity on the growth rate, and two species were more effected by a temperature than a salinity on the growth. In addition, prediction equations were obtained through the multiple regressions of the specific growth rates as ${\mu}=0.04+0.0193T-0.0339S- 0.0005T^2+0.0021S^2+0.00073TS-0.000022T^3-0.000038S^3+0.00000086TS^2-0.0000255T^2S$ in $A.$ $tamarense$ and ${\mu}=1.01-0.1288T-0.0778S+0.0067T^2+0.0038S^2+0.00204TS-0.0001T^3-0.000059S^3-0.0000131TS^2-0.0000392T^2S$ in $A.$ $catenella$. Correlation coefficient between experimental values and simulated values was highly indicated. These results seem to provide information for understanding the spreading mechanism of $A.$ $tamarense$ and $A.$ $catenella$.

• Journal of the korean society of oceanography
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• v.39 no.3
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• pp.172-185
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• 2004

LSU rDNA D1-D2 and SSU rDNA genes of 23 strains in seven Alexandrium (Halim) species, A. tamarense (Lebour) Balech, A. catenella (Whedon et Kofoid), A. fraterculus (Balech) Balech, A. affine (Inoue et Fukuyo) Balech, A. insuetum Balech, A. pseudogonyaulax (Biecheler) Horiguchi ex Yuki et Fukuyo and A. tamiyavanichii Balech, were sequenced and the data were used for molecular phylogenetic analysis. The sequence data revealed 11 and 7 ribotypes in the LSU rDNA D1-D2 region and 4 and 17 ribotypes in the SSU rDNA region of A. catenella and A. tamarense, respectively. Other Alexandrium species had also 1 to 5 ribotypes in the two regions. With the exception of CMC2 and CMC3 of A. catenella, all A. tamarense and A. catenella strains had a common ribotype, a functionally expressed rRNA gene (here termed type A), in both gene regions. In addition to the functionally expressed gene, several pseudogenes were obtained that were found to be good tools to analyze the population designation of regional isolates by grouping them according to shared ribotypes. From the phylogenetic analysis of the sequence data determined in this study and retrieved from GenBank, the genus Alexandrium was divided into 14 groups: 1) A. tamarense, 2) A. excavatum, 3) A. catenella, 4) Tasmanian A. tamarense, 5) A. affine (and/or A. concavum), 6) Thai A. tamarense, 7) A. tamiyavanichii, 8) A. fraterculus, 9) A. margalefii, 10) A. andersonii, 11) A. ostenfeldii, 12) A. minutum (or A. lusitanicum), 13) A. insuetum, and 14) A. pseudogonyaulax. The SSU rDNA gene sequence of A. fundyense was so similar to those of A. tamarense used in this study that the two species were difficult to discriminate each other. A. tamiyavanichii was closest to the A. tamarense strain isolated in Thailand and close to the long chain-forming species of A. affine and A. fraterculus. The phylogenetic tree showed that A. margalefii, A. andersonii, A. ostenfeldii, A. minutum and A. insuetum constituted the basal relative complex, and that A. pseudogonyaulax is an ancestral taxon in the genus Alexandrium.

• Proceedings of the Korean Aquaculture Society Conference
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• 2003.10a
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• pp.136-137
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• 2003

The marine dinoflagellate genus Alexandrium has been recognized as the most representative toxic phytoplankton on account of production of paralytic shellfish poisoning (PSP) throughout the world. PSP producers, generally A, tamarense and A. catenella, within the genus Alexandrium have caused high level intoxicauon of fisheries products and even death of human. In addition, more recent increasing of geographical range of this deleterious species has given rise to alarming tension. The study presented here aimed construction of the molecular phylogenetic relationships through sequences-determination from 16 morphotypic species (containing newly sequenced 3 morphotypic species, A. tamiyavainchii, A. fraterculus and A. pseudogonyaulax) in LSU rDNA D1-D2 and 12 morphotypic species (containing newly sequenced 6 - morphotypic species, A. catenella, A. tamiyavanichii, A. fraterculus, A. affine, A. insuetum and A. pseudogonyaulax) in SSU rDNA region, and the sequences were subjected to comparative-analysis in respect to regional population using functionally expressed rDNA genus and pseudogenes. And we discussed on genetic differentiation between A. tamarense and A. catenella together with putative PSP divegence of the genus Alexandrium. The results of phylogenetic analysis showed the robust monophyletic 14 distinct classes of A. tamarense, A. excavatum, A. catenella, Tasmanian A. tamarense, A. affine (and/or A. concavum), Thai A. tamarense, A. tamiyavanichii, A. fraterculus, A. margalefii, A. andersonii, A. ostenfeldii, A. minutum (and/or A. lusitanicum), A. insuetum, and A, pseudogonyaulx clade. A. fraterculus and A. tamiyavanichii were sister relationship and they were positioned independently between A, affine cluster and those of A. margalefi, A. andersonii, A. ostenfeldii, A. minutum and A. insuetum. A. pseudogonyaulax appeared to be an ancestral taxon among Alexandrium.

• ALGAE
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• v.17 no.1
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• pp.11-19
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• 2002

Twenty-nine culture strains belonging to the genus Alexandrium Halim (Dinophyceae) were established from water column or sediments in Korea. Seventeen isolates were identified as A. tamarense (Lebour) Balech, eight isolates as A. sp. cf. catenella and one as A. catenella (Whedon et Kofoid) Balech according to the presence or absence of a ventral pore, the shape of the posterior sulcal plate and the sulcal width. Three isolates were unable to be identified due to considerable distortion of thecal plates and lack of enough materials, but typical of A. tamarense and/or A. catenella. The overall cell shape of A. tamarense was usually longer than wide. The posterior sulcal plate was definitely longer than wide dorsoventrally, and sulcus extended posteriorly without apparent widening. They were distributed in three major coasts of Korea. In contrast, the cell shape of A. sp.cf. catenella was generally anterior-posteriorly flattened. The transversal axis of the posterior sulcal plate was always longer than the longitudinal, or both axes were nearly equal in length. Its sulcus was broader than that of A. tamarense and widened in the direction of antapex about 1.5 times. This morphotype existed in nearshore and offshore waters of the southern Korea sea. One of A. catenella isolates from Jinhae Bay showed no conspicuous differences with A. sp. cf. catenella except for the consistent absence of a ventral pore.

• Fisheries and Aquatic Sciences
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• v.9 no.1
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• pp.30-37
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• 2006

We performed experiments on the uptake and excretion of dissolved organic phosphorus (DOP) using two toxic dinoflagellates, Alexandrium tamarense Lebour (Balech) and Gymnodinium catenatum Graham, isolated from Hiroshima Bay, Japan. ATP (adenosine triphosphate), UMP (uridine-5-monophosphate), G-6-P (glucose-6-phosphate) and Glycero-P (glycerophosphate) were used as DOP sources in preliminary uptake experiments. ATP was selected as the DOP species for the short-tenn uptake experiment because preliminary experiments showed it to be the DOP source used by both species. Although the $K_s$ values of A. tamarense and G. catenatum (5.63 and $7.61{\mu}M$, respectively) obtained from the short-term experiments for ATP were only slightly higher than those reported for dissolved inorganic phosphorus (DIP), the ${\rho}_{max}$ values (5.04 pmol/cell/h and 13.4 pmol/cell/h, respectively) were much higher. The DOP excretion rate in batch-culture experiments was estimated at 0.084 pmol/cell/h for A. tamarense and 0.012 pmol/cell/h for G. catenatum, accounting for about 30% and 25%, respectively, of the assimilated phosphorus. Our results suggest that the DIP-depleted conditions of Hiroshima Bay favor these two species by supporting their ability to use DOP.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.40 no.1
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• pp.39-49
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• 2007

Species competition among the toxic dinoflagellates Alexandrium tamarense and Gymnodinium catenatum and the diatom Skeletonema costatum was simulated using a mathematical model. Prior to the model simulation competition experiments using the three species were conducted to obtain data for validation by the simulation model. S. costatum dominated at a density of ${\sim}10^{4}\;cells/mL$ compared to the other species in the medium with dissolved inorganic phosphorus (DIP). The growth of S. costatum was also stimulated by the addition of dissolved organic phosphorus (DOP), such as uridine-5-monophosphate (UMP) or glycerophosphate (Glycero-P), although this species is unable to take up DOP. This implies that the growth of S. costatum may be supported by DIP, which is hydrolyzed by alkaline phosphatase produced from A. tamarense and G. catenatum. The species competition model was run assuming the environmental conditions of northern Hiroshima Bay, Japan, during spring and summer. G. catenatum increased in cell density and neared the level of S. costatum at the end of the calculation. In the sensitivity analyses by means of doubling and halving parameters, depleted DIP had little effect on the cell density of G. catenatum. However the growth of A. tamarense and S. costatum was significantly affected by changes in the parameter values. These results indicate that if DIP depletion is ongoing, species that have a large phosphate pool in their cells, such as G. catenatum, will predominate in the community.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.39 no.1
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• pp.49-54
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• 2006

Cultured cells of the toxic Alexandrium tamarense were fed to four mussel species, Mytilus coruscus, M. edulis, M. galloprovincialis and Septifer vulgatus, to examine the interspecies and interlocality differences in the ability to accumulate paralytic shellfish poisoning (PSP) toxins. Toxin content of A. tamarense cells varied during culture period. In contrast, toxin composition in the cell (C1,2, GTX1-4 and neoSTX) was constantly stable. In feeding experiment, the four mussel species collected from Geoje intoxicated after uptake of A. tamarense. Toxin content ($average{\pm}SD\;{\mu}g$ STXeq/100 g) of M. coruscus, M. edulis, M. galloprovincialis and Septifer vulgatus were $1,660{\pm}79,\;3,914{\pm}2,242,\;5,626{\pm}1,620\;and\;958{\pm}163$, respectively. Toxin profiles included C1,2, GTX1,4 and neoSTX as the major components, and dcGTX2,3, GTX2,3, neoSTX and STX as the minor ones. Toxin accumulation of three mussel species collected from Pohang, Geoje and Anmyon-do showed interspecies and interlocality differences. Toxin content ($average{\pm}SD\;{\mu}g$ STXeq/100 g) were $91{\pm}4,\;151{\pm}14,\;39{\pm}3$ in M coruscus, $189{\pm}1,\;231{\pm}11,\;206{\pm}15$ in M edu/is and $214{\pm}28,\;326{\pm}30,\;291{\pm}26$ in M. galloprovincialis in order of Anmyon-do, Geoje and Pohang.

• Journal of Life Science
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• v.12 no.6
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• pp.821-834
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• 2002

In order to measure the inter- and intraspecific genetic divergences within the genus Alexandrium, the variations within the internal transcribed spacer (ITS1 and ITS2) regions and 5.85 ribosomal RNA gene of eight Alexandrium species were examined for 33 strains from diverse geographical locations by direct sequencing. Five isolates of A. tamarense (AT-2, AT-6, AT-10, AT-A and AT-B) from Jinhae Bay, Korea were found to be completely identical to a Japanese strain OFX151-A. The length of the amplified ITSI-5.85-ITS2 region varied from 481 nucleotides (in A. margalefi) to 528 nucleotides (in A. affine CU1-1). ITS1 and ITS2 nucleotide lengths were negatively correlated, whereas a positive correlation was found between their G＋C content. The degree of sequence divergence ranged from 0.3% (1 bp) to a maximum of 53% (305 Up). Pairwise sequence comparisons revealed a small degree of divergence between A. tamarense and A. Pundyense isolates (1.2 - 2.3% ＝ 6-12 bp), but a high degree of divergence between A. tamarense and A. catenella (19.8% ＝ 102 bp), and between A. catenella and A. Pundyense (19.7%). Although most nodes were weakly supported by bootstrap values, some types tend to form independent molecular groups. A. catenella isolates also formed an independent molecular sub-group, with relaticula strong bootstrap values (94% or 85% and 79% or 98%, respectively in PAUP and NJ trees). Interestingly, A. cohorticula and A. frateculus always clustered within the same sub-group, this result being supported by strong bootstrap values. Our results indicate that the ITS regions provide useful informations on hierarchical population genetic structure and a high phylogenetic resolution in intraspecific and interspecific Alexandrium population.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.7
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• pp.3582-3588
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• 2013

Expressed sequence tag (EST) library was constructed from A. tamarense. Base sequences of EST clones were analyzed and saxitoxin biosynthesis-related genes were cloned. Sequences of 827 clones were analyzed and 564 EST were functionally clustered using Blast searches against GenBank. Main genes in the EST had functions on cellular organization, cell metabolism, energy, cell cycle and DNA processing, cellular transport and transport, cell rescue, defense, death and aging, and transcription. Moreover, expression of S-adenosylmethionine synthetase and H2A histone family genes were increased in the toxic A. tamarense. These results show that two genes could be a good biomarkers for the detection of saxitoxin biosynthesis in the A. tamarense.

• Journal of Microbiology and Biotechnology
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• v.15 no.5
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• pp.1094-1099
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• 2005

Photosynthetic dinoflagellates contain a water-soluble, light-harvesting antenna called the peridinin-chlorophyll-protein (PCP) complex, which has an apoprotein with no sequence similarity to other known proteins. There are two forms of PCP apoproteins; the 15-kDa short form and the 32- to 35­kDa long form. The present study describes the PCP protein and its cDNA from Alexandrium tamarense. A cDNA library was constructed from mRNA isolated from A. tamarense. The complete PCP cDNA was generated by reverse-transcription coupled to polymerase chain reaction (RT-PCR), together with rapid-amplification of cDNA ends (RACE). The A. tamarense PCP cDNA encoded a 55-amino acid signal peptide and a 313-amino acid mature protein with a calculated mass of 32 kDa, which corresponded to that of the long form of PCP. Phylogenetic analysis indicated that the sequence of A. tamarense PCP did not cluster with the short-form PCPs, to which it was only about $55\%$ identical, but which were $79-83\%$ identical to other long-form PCPs. The deduced amino acid sequence of A. tamarense PCP contains an internal duplication, which suggests the possibility that long-form PCPs arose by gene duplication or by the fusion of genes encoding the short form. The abundance of PCP mRNA changed substantially in response to different light conditions, indicating the possible existence of a photo-acclimation response in A. tamarense.