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Allen R Place - One of the best experts on this subject based on the ideXlab platform.
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pilot scale outdoor photobioreactor culture of the marine dinoflagellate Karlodinium veneficum production of a karlotoxins rich extract
Bioresource Technology, 2018Co-Authors: L Lopezrosales, Allen R Place, F Garciacamacho, A Sanchezmiron, Yusuf Chisti, E MolinagrimaAbstract:Abstract A pilot-scale bioprocess was developed for the production of karlotoxin-enriched extracts of the marine algal dinoflagellate Karlodinium veneficum. A bubble column and a flat-panel photobioreactors (80–281 L) were used for comparative assessment of growth. Flow hydrodynamics and energy dissipation rates (EDR) in the bioreactors were characterized through robust computational fluid dynamic simulations. All cultures were conducted monoseptically outdoors. Bubble column (maximum cell productivity in semicontinuous operation of 58 × 103 cell mL−1 day−1) proved to be a better culture system for this alga. In both reactors, the local EDR near the headspace, and in the sparger zone, were more than one order of magnitude higher than the average value in the whole reactor (=4 × 10−3 W kg−1). Extraction of the culture and further purification resulted in the desired KTXs extracts. Apparently, the alga produced three congeners KTXs: KmTx-10 and its sulfated derivative (sulfo-KmTx-10) and KmTx-12. All congeners possessed hemolytic activity.
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two new karlotoxins found in Karlodinium veneficum strain gm2 from the east china sea
Harmful Algae, 2016Co-Authors: Pengjie Cai, Allen R Place, Chengxu Zhou, Saddef Haq, Lijian Ding, Haimin Chen, Ying Jiang, Cheng Guo, Jinrong Zhang, Xiaojun YanAbstract:The dinoflagellate Karlodinium veneficum is a harmful algal bloom species with a worldwide distribution. This small athecate dinoflagellate makes a family of polyketide toxins that are hemolytic, cytotoxic and ichthyotoxic. The first chemical structure for karlotoxins from East China Sea (ECS) is reported here. The two new karlotoxins, namely 4,5-dihydro-KmTx 2 (compound 1) and 4,5-dihydro-dechloro-KmTx 2 (compound 2), were isolated and purified from monoalgal cultures of K. veneficum strain GM2. Their structures were determined by spectroscopic analysis, including tandem mass spectrometry as well as 1D and 2D NMR experiments. These new karlotoxin congeners feature a saturated polyol arm different from previously reported for KmTx 2 that appears to increase hemolytic activity.
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stereochemical studies of the karlotoxin class using nmr spectroscopy and dp4 chemical shift analysis insights into their mechanism of action
Angewandte Chemie, 2015Co-Authors: Amanda L Waters, Allen R Place, Mark T HamannAbstract:After publication of karlotoxin 2 (KmTx2; 1), the harmful algal bloom dinoflagellate Karlodinium sp. was collected and scrutinized to identify additional biologically active complex polyketides. The structure of 1 was validated and revised at C49 using computational NMR tools including J-based configurational analysis and chemical-shift calculations. The characterization of two new compounds [KmTx8 (2) and KmTx9 (3)] was achieved through overlaid 2D HSQC NMR techniques, while the relative configurations were determined by comparison to 1 and computational chemical-shift calculations. The detailed evaluation of 2 using the NCI-60 cell lines, NMR binding studies, and an assessment of the literature supports a mode of action (MoA) for targeting cancer-cell membranes, especially of cytostatic tumors. This MoA is uniquely different from that of current agents employed in the control of cancers for which 2 shows sensitivity.
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interactions between Karlodinium veneficum and prorocentrum donghaiense from the east china sea
Harmful Algae, 2015Co-Authors: Chengxu Zhou, Allen R Place, Qijun Luo, Xiaojun Yan, Ernest William, Ying JiangAbstract:The dinoflagellate Prorocentrum donghaiense is a dominant harmful algal bloom (HAB) species on the East China Sea (ECS) coast. The co-occurrence of Karlodinium veneficum with P. donghaiense is often observed and can later develop into dense blooms. However, the role of K. veneficum in P. donghaiense population dynamics is unknown. In the current study, three K. veneficum (GM1, GM2, and GM3) strains were isolated from the ECS with one (GM1) from a mixed, dense bloom of P. donghaiense and other HAB species. All three isolates had identical ITS sequences that were concordant with the species designation. Unique karlotoxin congeners were isolated from one strain (GM2). The sterol compositions of P. donghaiense and K. veneficum were consistent with sensitivity to karlotoxin in the former and insensitivity in the latter. Additional experimentation showed that: (1)in monocultures, higher growth rate of P. donghaiense than K. veneficum is observed in nutrient-enriched and nutrient-depleted media. In co-cultures, the growth of P. donghaiense is inhibited; (2) feeding on P. donghaiense by K. veneficum is clearly demonstrated by fluorescent dye tracking; and (3) the isolated karlotoxin is lethal to P. donghaiense in a concentration-dependent manner. From these studies we propose that K. veneficum may play a negative role in P. donghaiense bloom maintenance and that P. donghaiense may in turn be a bloom initiator as a prey item for K. veneficum.
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the cytotoxic mechanism of karlotoxin 2 kmtx 2 from Karlodinium veneficum dinophyceae
Aquatic Toxicology, 2015Co-Authors: Jonathan R. Deeds, Allen R Place, Robert E Hoesch, Joseph P Y KaoAbstract:This study demonstrates that the polyketide toxin karlotoxin 2 (KmTx 2) produced by Karlodinium veneficum, a dinoflagellate associated with fish kills in temperate estuaries world-wide, alters vertebrate cell membrane permeability. Microfluorimetric and electrophysiological measurements were used to determine that vertebrate cellular toxicity occurs through non-selective permeabilization of plasma membranes, leading to osmotic cell lysis. Previous studies showed that KmTx 2 is lethal to fish at naturally-occurring concentrations measured during fish kills, while sub-lethal doses severely damage gill epithelia. This study provides a mechanistic explanation for the association between K. veneficum blooms and fish kills that has long been observed in temperate estuaries worldwide.
Margarita Fernandeztejedor - One of the best experts on this subject based on the ideXlab platform.
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detection and quantification of the toxic marine microalgae Karlodinium veneficum and Karlodinium armiger using recombinase polymerase amplification and enzyme linked oligonucleotide assay
Analytica Chimica Acta, 2018Co-Authors: Anna Toldrà, Karl B. Andree, Jorge Diogène, Margarita Fernandeztejedor, Miriam Jausetrubio, Ioanis Katakis, Ciara K Osullivan, Mònica CampàsAbstract:Abstract Karlodinium is a dinoflagellate responsible for fish-killing events worldwide. In Alfacs Bay (NW Mediterranean Sea), the presence of two Karlodinium species (K. veneficum and K. armiger) with different toxicities has been reported. This work presents a method that combines recombinase polymerase amplification (RPA) with an enzyme-linked oligonucleotide assay (ELONA) to identify, discriminate and quantify these two species. The system was characterised using synthetic DNA and genomic DNA, and the specificity was confirmed by cross-reactivity experiments. Calibration curves were constructed using 10-fold dilutions of cultured cells, attaining a limit of detection of around 50,000 cells/L, far below the Karlodinium spp. alert threshold (200,000 cells/L). Finally, the assay was applied to spiked seawater samples, showing an excellent correlation with the spiking levels and light microscopy counts. This approach is more rapid, specific and user-friendly than traditional microscopy techniques, and shows great promise for the surveillance and management of harmful algal blooms.
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artificial neural network approach to population dynamics of harmful algal blooms in alfacs bay nw mediterranean case studies of Karlodinium and pseudo nitzschia
Ecological Modelling, 2016Co-Authors: Carles Guallar, Jorge Diogène, Maximino Delgado, Margarita FernandeztejedorAbstract:Abstract The dinoflagellate Karlodinium and the diatom Pseudo-nitzschia are bloom-forming genera frequently present in Alfacs Bay. Both microalgae are associated with toxic events. Therefore, understanding their population dynamics and predict their occurrence in short-term is crucial for an optimal management of toxic events for the local shellfish production and ecosystem managers. Artificial neural networks have been successfully used to model the complex nonlinear dynamics of phytoplankton. In this study, this approach was applied to predict absence-presence and abundance of Karlodinium and Pseudo-nitzschia microalgae in Alfacs Bay (NW Mediterranean) using biological and/or environmental variables. Neural Interpretation Diagram (NID) and Connection Weight Approach (CWA) methodologies were applied to obtain ecological information from the models. The dataset used was long-term (1990⿿2015) time series of environmental and phytoplankton variables from different monitoring stations established in Alfacs Bay (Ebre Delta), meteorological data and Ebre River flow rates. Several models were presented. The best ones were achieved for one-week ahead procedures performed with environmental and biological variables using all the available data. A sensitivity analysis showed the larger the data set used, the better the models obtained. However, Karlodinium absence-presence models developed with five years of data present high accuracy. The size of the neural networks denotes complex relationships between environmental and phytoplankton variables. The environmental variables had stronger influence on the abundance models while biological variables had more importance in the absence-presence models. These results highlight a complex ecosystem in Alfacs Bay involving anthropogenic, climatic and hydrologic factors forcing phytoplankton dynamics. In addition, a change in the ecosystem dynamics regarding Karlodinium is detected. The configuration and the accuracy achieved with the models allow their use in different real-world applications as automated systems and/or monitoring programs.
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mitigation of lethal effects of Karlodinium veneficum and k armiger on sparus aurata changes in haematocrit and plasma osmolality
Diseases of Aquatic Organisms, 2007Co-Authors: Margarita Fernandeztejedor, Angeles M Soubrierpedreno, Dolores M FuronesAbstract:Between January and April 2000, several experiments were performed during a Karlodinium spp. proliferation in Alfacs Bay (Ebro delta, NW Mediterranean) to determine the effects of these dinoflagellates on sea bream Sparus aurata cultivated in the area. Moribund fish showed an increase in plasma osmolality together with a decrease in the haematocrit percentage compared to control fish. The efficacy of copper sulphate, hydrogen peroxide, potassium permanganate and formalin against Karlodinium spp. was also tested. None of these treatments had mitigation effects when applied in the presence of fish; on the contrary, lethal effects appeared at lower Karlodinium spp. densities compared to fish control groups. When a lytic agent, such as copper sulphate, was used as a water pre-treatment, in the absence of fish, Karlodinium spp. toxicity was significantly reduced. Protocols for water pre-treatments were studied as a potential tool for combating Karlodinium spp. in fish farms.
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on the identity of Karlodinium veneficum and description of Karlodinium armiger sp nov dinophyceae based on light and electron microscopy nuclear encoded lsu rdna and pigment composition1
Journal of Phycology, 2006Co-Authors: Trine Bergholtz, Niels Daugbjerg, Ojvind Moestrup, Margarita FernandeztejedorAbstract:An undescribed species of the dinoflagellate genus Karlodinium J. Larsen (viz. K. armiger sp. nov.) is described from Alfacs Bay (Spain), using light and electron microscopy, pigment composition, and partial large subunit (LSU) rDNA sequence. The new species differs from the type species of Karlodinium (K. micrum (Leadbeater et Dodge) J. Larsen) by lacking rows of amphiesmal plugs, a feature presently considered to be a characteristic of Karlodinium. In K. armiger, an outer membrane is underlain by a complex system of cisternae and vacuoles. The pigment profile of K. armiger revealed the presence of chlorophylls a and c, with fucoxanthin as the major carotenoid. Phylogenetic analysis confirmed K. armiger to be related to other species of Karlodinium; thus forming a monophyletic genus, which, in the LSU tree, occupies a sister group position to Takayama de Salas, Bolch, Botes et Hallegraeff. The culture used by Ballantine to describe Gymnodinium veneficum Ballantine (Plymouth 103) was examined by light and electron microscopy and by partial LSU rDNA. Ultrastructurally, it proved identical to K. micrum (cultures Plymouth 207 and K. Tangen KT-77D, the latter also known as K-0522), and in LSU sequence, differed in only 0.3% of 1438 bp. We consider the two taxa to belong to the same species. This necessitates a change of name for the most widely found species, K. micrum, to K. veneficum. The three genera Karlodinium, Takayama, and Karenia constitute a separate evolutionary lineage, for which the new family Kareniaceae fam. nov. is suggested.
Xiaojun Yan - One of the best experts on this subject based on the ideXlab platform.
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biochemical characteristics support the recently described species Karlodinium zhouanum gymnodiniales dinophyceae
Phycological Research, 2020Co-Authors: Xiaojuan Zhu, Zhaohe Luo, Chengxu Zhou, Ran Meng, Keyi Fang, Qijun Luo, Xiaojun YanAbstract:The small athecate dinoflagellate Karlodinium zhouanum is a species recently described in the coastal waters of China. K. zhouanum is morphologically similar to Karlodinium veneficum, a typical ichthyotoxic blooming karlotoxin‐producing species, and it is impossible to distinguish between these two species based on light microscopy. In this study, strains of K. zhouanum isolated from the East China Sea were studied. By analyzing toxins, toxicity, lipid characteristics and typical molecular and physiological traits of this species, K. zhouanum was shown to be nontoxic to brine shrimp and widely spread over the coastal waters of China. No karlotoxin‐like toxin was detected by liquid chromatography‐mass spectrometry (LC–MS). Instead of gymnodinosterol, the critical sterol in toxic K. veneficum, 27(nor)‐24S‐4α‐Methyl‐5α‐ergosta‐8(14)‐en‐3β‐ol (NEE) was dominant in K. zhouanum, while gymnodinosterol was absent. These sterol characteristics may provide not only support for the species separation between toxic and nontoxic species of Karlodinium but also environmental survey tools to differentiate the contribution of nontoxic Karlodinium strains, which has been unclear until now.
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the development of loop mediated isothermal amplification combined with lateral flow dipstick for detection of Karlodinium veneficum
Harmful Algae, 2017Co-Authors: Hailong Huang, Chengxu Zhou, Peng Zhu, Xiaojun YanAbstract:The aim of this study was to develop a loop-mediated isothermal amplification (LAMP) combined with a chromatographic lateral flow dipstick (LFD) assay to rapidly and specifically detect the Karlodinium veneficum ITS gene. Four groups of LAMP primers were specially designed to target the K. veneficum ITS gene. The LAMP-LFD detection limit was 7.4pg/μL (approximately 6.5cells/mL) of K. veneficum genomic DNA and was 10 times more sensitive than standard PCR. The LAMP-LFD method exhibited high specificity and accurately identified K. veneficum algal isolates, but not other algal isolates. To test the assay's accuracy, samples from positive results were further analyzed by sequencing and phylogenetic analysis, all of which were identified as K. veneficum. Over all, the LAMP-LFD assay established in this paper can be used as a reliable and simple method to detect the K. veneficum.
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two new karlotoxins found in Karlodinium veneficum strain gm2 from the east china sea
Harmful Algae, 2016Co-Authors: Pengjie Cai, Allen R Place, Chengxu Zhou, Saddef Haq, Lijian Ding, Haimin Chen, Ying Jiang, Cheng Guo, Jinrong Zhang, Xiaojun YanAbstract:The dinoflagellate Karlodinium veneficum is a harmful algal bloom species with a worldwide distribution. This small athecate dinoflagellate makes a family of polyketide toxins that are hemolytic, cytotoxic and ichthyotoxic. The first chemical structure for karlotoxins from East China Sea (ECS) is reported here. The two new karlotoxins, namely 4,5-dihydro-KmTx 2 (compound 1) and 4,5-dihydro-dechloro-KmTx 2 (compound 2), were isolated and purified from monoalgal cultures of K. veneficum strain GM2. Their structures were determined by spectroscopic analysis, including tandem mass spectrometry as well as 1D and 2D NMR experiments. These new karlotoxin congeners feature a saturated polyol arm different from previously reported for KmTx 2 that appears to increase hemolytic activity.
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interactions between Karlodinium veneficum and prorocentrum donghaiense from the east china sea
Harmful Algae, 2015Co-Authors: Chengxu Zhou, Allen R Place, Qijun Luo, Xiaojun Yan, Ernest William, Ying JiangAbstract:The dinoflagellate Prorocentrum donghaiense is a dominant harmful algal bloom (HAB) species on the East China Sea (ECS) coast. The co-occurrence of Karlodinium veneficum with P. donghaiense is often observed and can later develop into dense blooms. However, the role of K. veneficum in P. donghaiense population dynamics is unknown. In the current study, three K. veneficum (GM1, GM2, and GM3) strains were isolated from the ECS with one (GM1) from a mixed, dense bloom of P. donghaiense and other HAB species. All three isolates had identical ITS sequences that were concordant with the species designation. Unique karlotoxin congeners were isolated from one strain (GM2). The sterol compositions of P. donghaiense and K. veneficum were consistent with sensitivity to karlotoxin in the former and insensitivity in the latter. Additional experimentation showed that: (1)in monocultures, higher growth rate of P. donghaiense than K. veneficum is observed in nutrient-enriched and nutrient-depleted media. In co-cultures, the growth of P. donghaiense is inhibited; (2) feeding on P. donghaiense by K. veneficum is clearly demonstrated by fluorescent dye tracking; and (3) the isolated karlotoxin is lethal to P. donghaiense in a concentration-dependent manner. From these studies we propose that K. veneficum may play a negative role in P. donghaiense bloom maintenance and that P. donghaiense may in turn be a bloom initiator as a prey item for K. veneficum.
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toxicological studies of Karlodinium micrum dinophyceae isolated from east china sea
Toxicon, 2011Co-Authors: Chengxu Zhou, Yurong You, Nuria Fernandez, Haiming Chen, Xiaojun YanAbstract:Abstract Karlodinium micrum (Strain NMBjah047) was isolated from the water samples of East China Sea (ECS). The hemolytic, ichthyotoxic, and cytotoxic activities of the algae was characterized. Embryotoxicity of both intra and extracellular extracts were also tested on a local sea urchin species. The algal intracellular hemolytic toxicity averaged about 87.5% at different algal growth phases. However, extracellular hemolytic activity depended on the population growth phase. The toxicity increased with the increase in the population size, reaching the highest hemolytic activity during the stationary phase, and maintained a relatively high activity even when the population declined. Time and density dependent ichthyotoxicity to Lateolabrax maculates juveniles was also detected. The LD50 in 24 h was 1.1 × 105 cells/mL. Inhibition of the fertilized egg hatching was also observed and estimated the IC50 in 40 h with 3.5 × 104 cells/mL. Extracellular extracts of K. micrum dense culture also showed significant cytotoxic activity on HUVEC (IC50 = 70.8 μg/mL). A dose dependent acute toxicity to embryos of sea urchin was also determined. The algal intracellular and extracellular extracts delayed or even restricted the embryological development of the sea urchin, illustrating the potential toxicity of K. micrum not only to vertebrates, but also to marine invertebrates. The hemolytic compounds in the ECS strain were extracted and analyzed. At least two fractions had significant hemolytic activities. A lipid-like compound, named Digalactosyldiacylglycerol (DGDG), was suggested to be responsible for the hemolytic activity in one of these fractions. From the results of the present studies, this strain of K. micrum isolated from the East China Sea might be considered a toxic strain with hemolytic activity, ichthyotoxicity, cytotoxicity and embryotoxicity.
Ying Zhong Tang - One of the best experts on this subject based on the ideXlab platform.
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plasticity and multiplicity of trophic modes in the dinoflagellate Karlodinium and their pertinence to population maintenance and bloom dynamics
Journal of Marine Science and Engineering, 2021Co-Authors: Huijiao Yang, Ying Zhong TangAbstract:As the number of mixotrophic protists has been increasingly documented, “mixoplankton”, a third category separated from the traditional categorization of plankton into “phytoplankton” and “zooplankton”, has become a new paradigm and research hotspot in aquatic plankton ecology. While species of dinoflagellates are a dominant group among all recorded members of mixoplankton, the trophic modes of Karlodinium, a genus constituted of cosmopolitan toxic species, were reviewed due to their representative features as mixoplankton and harmful algal blooms (HABs)-causing dinoflagellates. Among at least 15 reported species in the genus, three have been intensively studied for their trophic modes, and all found to be phagotrophic. Their phagotrophy exhibits multiple characteristics: (1) omnivority, i.e., they can ingest a variety of preys in many forms; (2) flexibility in phagotrophic mechanisms, i.e., they can ingest small preys by direct engulfment and much bigger preys by myzocytosis using a peduncle; (3) cannibalism, i.e., species including at least K. veneficum can ingest the dead cells of their own species. However, for some recently described and barely studied species, their tropical modes still need to be investigated further regarding all of the above-mentioned aspects. Mixotrophy of Karlodinium plays a significant role in the population dynamics and the formation of HABs in many ways, which thus deserves further investigation in the aspects of physiological ecology, environmental triggers (e.g., levels of inorganic nutrients and/or presence of preys), energetics, molecular (genes and gene expression regulations) and biochemical (e.g., relevant enzymes and signal molecules) bases, origins, and evaluation of the advantages of being a phagotroph.
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Contact micropredation may play a more important role than exotoxicity does in the lethal effects of Karlodinium australe blooms: Evidence from laboratory bioassays.
Harmful algae, 2020Co-Authors: Xiaoying Song, Lixia Shang, Chui Pin Leaw, Po Teen Lim, Ying Zhong TangAbstract:Abstract Multiple dinoflagellate species from the genus Karlodinium have been well known to form massive and toxic blooms that consequently cause fish kills in many coastal waters around the world. Karlodinium australe is a mixotrophic and potentially ichthyotoxic species associated with fish kills. Here, we investigated phagotrophy of K. australe (isolate KaJb05) established from a bloom event in the West Johor Strait, Malaysia, using several prey species (phytoplankton, zooplankton, and larval fish). The results showed that K. australe ingested relatively small prey cells of co-occurring microalgae by direct engulfment, while it fed on larger prey cells of microalgae by tube feeding. The results of animal exposure bioassays using rotifer (Brachionus plicatilis), brine shrimp (Artemia salina), and larval fish (Oryzias melastigma) demonstrated that phagotrophy (in terms of the trophic mode of the dinoflagellate), or micropredation (in terms of the mechanism of lethal effects on prey), played a more important role than the toxicity did in causing the lethal effects of K. australe on these aquatic animals under low cell densities of K. australe, while the mortalities of animals observed in the exposure to cell lysates of K. australe were solely caused by the toxicity. A comparison of the lethal effects between K. australe and K. veneficum revealed that the lethal effect of K. australe on rotifers was much stronger than that of K. veneficum at all cell densities applied in the experiments and the more "aggressive" micropredation of K. australe is suggested to explain the difference in lethal effect between K. austale and K. veneficum. Our results may explain why K. australe exhibited fish killings during moderate blooms at cell densities
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a strain of the toxic dinoflagellate Karlodinium veneficum isolated from the east china sea is an omnivorous phagotroph
Harmful Algae, 2020Co-Authors: Huijiao Yang, Zhangxi Hu, Lixia Shang, Yunyan Deng, Ying Zhong TangAbstract:Abstract Karlodinium veneficum is a cosmopolitan, toxic, and harmful algal bloom-forming dinoflagellate, of which the mixotrophy has been suggested to be a key factor in the formation and maintaining of HABs and thus deserves more intensive explorations. Here, we report an investigation on the phagotrophy of K. veneficum using a clonal culture isolated from the coastal water of East China Sea. We found K. veneficum is an omnivorous phagotroph feeding on both live and dead bodies/cells of a fish (Oryzias melastigma), brine shrimp (Artemia salina), rotifer (Brachionus plicatilis), co-cultivated microalgae Akashiwo sanguinea, Margalefidinium polykrikoides, Alexandrium leei, Rhodomonas salina, Isochrysis galbana, and its own species. Karlodinium veneficum extracted the cell contents of all species provided through either a peduncle (i.e. myzocytosis) or by engulfing the whole cell of small preys (i.e. phagotrophy sensu stricto). Karlodinium veneficum preferred to ingest non-motile or newly dead preys, no matter whether they were fish, zooplankton, or phytoplankton. Importantly, K. veneficum exhibited micropredation on animals with sizes much larger than itself (fish, rotifer, and brine shrimp), especially when they were injured or newly dead. The LysoSensor- and LysoTracker-stained lysosomes or/and phagolysosomes of K. veneficum increased when preys were added. Cannibalism in K. veneficum, i.e. a cell feeds on other unhealthy or dead cells of the same species, was observed as the first time in the study, which can help the growth and elongated maintaining of the population under nutrient deficiency (i.e. the culture maintained viable in culture plates without nutrient supplement up to a year). The growth rate of K. veneficum exhibited significant positive correlation with ingestion rate, which differed among prey species, and the highest growth rate was observed when feeding on R. salina. The ingest ability of K. veneficum was triggered by nutrient deficiency. In conclusion, the omnivorous mixotrophy is proposed to be a key autecological mechanism for K. veneficum to widen its ecological niche and succeed in forming a cosmopolitan distribution and frequent blooms.
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a strain of the toxic dinoflagellate Karlodinium veneficum isolated from the east china sea is an omnivorous phagotroph
Harmful Algae, 2020Co-Authors: Huijiao Yang, Zhangxi Hu, Lixia Shang, Yunyan Deng, Ying Zhong TangAbstract:Abstract Karlodinium veneficum is a cosmopolitan, toxic, and harmful algal bloom-forming dinoflagellate, of which the mixotrophy has been suggested to be a key factor in the formation and maintaining of HABs and thus deserves more intensive explorations. Here, we report an investigation on the phagotrophy of K. veneficum using a clonal culture isolated from the coastal water of East China Sea. We found K. veneficum is an omnivorous phagotroph feeding on both live and dead bodies/cells of a fish (Oryzias melastigma), brine shrimp (Artemia salina), rotifer (Brachionus plicatilis), co-cultivated microalgae Akashiwo sanguinea, Margalefidinium polykrikoides, Alexandrium leei, Rhodomonas salina, Isochrysis galbana, and its own species. Karlodinium veneficum extracted the cell contents of all species provided through either a peduncle (i.e. myzocytosis) or by engulfing the whole cell of small preys (i.e. phagotrophy sensu stricto). Karlodinium veneficum preferred to ingest non-motile or newly dead preys, no matter whether they were fish, zooplankton, or phytoplankton. Importantly, K. veneficum exhibited micropredation on animals with sizes much larger than itself (fish, rotifer, and brine shrimp), especially when they were injured or newly dead. The LysoSensor- and LysoTracker-stained lysosomes or/and phagolysosomes of K. veneficum increased when preys were added. Cannibalism in K. veneficum, i.e. a cell feeds on other unhealthy or dead cells of the same species, was observed as the first time in the study, which can help the growth and elongated maintaining of the population under nutrient deficiency (i.e. the culture maintained viable in culture plates without nutrient supplement up to a year). The growth rate of K. veneficum exhibited significant positive correlation with ingestion rate, which differed among prey species, and the highest growth rate was observed when feeding on R. salina. The ingest ability of K. veneficum was triggered by nutrient deficiency. In conclusion, the omnivorous mixotrophy is proposed to be a key autecological mechanism for K. veneficum to widen its ecological niche and succeed in forming a cosmopolitan distribution and frequent blooms.
Mònica Campàs - One of the best experts on this subject based on the ideXlab platform.
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detection and quantification of the toxic marine microalgae Karlodinium veneficum and Karlodinium armiger using recombinase polymerase amplification and enzyme linked oligonucleotide assay
Analytica Chimica Acta, 2018Co-Authors: Anna Toldrà, Karl B. Andree, Jorge Diogène, Margarita Fernandeztejedor, Miriam Jausetrubio, Ioanis Katakis, Ciara K Osullivan, Mònica CampàsAbstract:Abstract Karlodinium is a dinoflagellate responsible for fish-killing events worldwide. In Alfacs Bay (NW Mediterranean Sea), the presence of two Karlodinium species (K. veneficum and K. armiger) with different toxicities has been reported. This work presents a method that combines recombinase polymerase amplification (RPA) with an enzyme-linked oligonucleotide assay (ELONA) to identify, discriminate and quantify these two species. The system was characterised using synthetic DNA and genomic DNA, and the specificity was confirmed by cross-reactivity experiments. Calibration curves were constructed using 10-fold dilutions of cultured cells, attaining a limit of detection of around 50,000 cells/L, far below the Karlodinium spp. alert threshold (200,000 cells/L). Finally, the assay was applied to spiked seawater samples, showing an excellent correlation with the spiking levels and light microscopy counts. This approach is more rapid, specific and user-friendly than traditional microscopy techniques, and shows great promise for the surveillance and management of harmful algal blooms.
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Dual quantitative PCR assay for identification and enumeration of Karlodinium veneficum and Karlodinium armiger combined with a simple and rapid DNA extraction method
Journal of Applied Phycology, 2018Co-Authors: Anna Toldrà, Karl B. Andree, Margarita Fernández-tejedor, Jorge Diogène, Mònica CampàsAbstract:Karlodinium is a dinoflagellate genus responsible for massive fish mortality events worldwide. It is commonly found in Alfacs Bay (NW Mediterranean Sea), where the presence of two Karlodinium species (K. veneficum and K. armiger) with different toxicities has been reported. Microscopy analysis is not able to differentiate between these two species. Therefore, new and rapid methods that accurately and specifically detect and differentiate these two species are crucial to facilitate routine monitoring, to provide early warnings and to study population dynamics. In this work, a quantitative real-time PCR (qPCR) method to detect and enumerate K. veneficum and K. armiger is presented. The ITS1 region of the ribosomal DNA was used to design species-specific primers. The specificity of the primers together with the melting curve profile provided a reliable qualitative identification and discrimination between the two Karlodinium species. Additionally, a simple and rapid DNA extraction method was used. Standard curves were constructed from 10-fold dilutions of cultured microalgae cells. Finally, the applicability of the assay was tested with field samples collected from Alfacs Bay. Results showed a significant correlation between qPCR determinations and light microscopy counts (y = 2.838 x + 564; R2 = 0.936). Overall, the qPCR method developed herein is specific, rapid, accurate, and promising for the detection of these two Karlodinium species in environmental samples.
