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

Bergholtz, Trine; Daugbjerg, Niels; Moestrup, Øjvind; Fernández-Tejedor, Margarita

doi:10.1111/j.1529-8817.2006.00172.x

Cited by 162 publications

(151 citation statements)

References 34 publications

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Section: Introductionmentioning

confidence: 99%

“…Species of Karlodinium are less than 20 mm in length and 15 mm in width and require electron microscopy and/or DNA sequence analyses for proper species identification (Bergholtz et al, 2005;de Salas et al, 2005), which was not available for this study. Species of Karlodinium possess permanent chloroplasts of haptophyte endosymbiotic origin (Bergholtz et al, 2005) and seem to be obligate phototrophs (that is, unable to survive without light). However, the two species investigated in this study Karlodinium armiger and Karlodinium veneficum are mixotrophic and use feeding tubes to phagocytise microalgal prey to obtain faster growth rates (Li et al, 1999;Berge et al, 2008a).…”

Section: Introductionmentioning

confidence: 99%

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Marine microalgae attack and feed on metazoans

et al. 2012

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Free-living microalgae from the dinoflagellate genus Karlodinium are known to form massive blooms in eutrophic coastal waters worldwide and are often associated with fish kills. Natural bloom populations, recently shown to consist of the two mixotrophic and toxic species Karlodinium armiger and Karlodinium veneficum have caused fast paralysis and mortality of finfish and copepods in the laboratory, and have been associated with reduced metazooplankton biomass in-situ. Here we show that a strain of K. armiger (K-0688) immobilises the common marine copepod Acartia tonsa in a densitydependent manner and collectively ingests the grazer to promote its own growth rate. In contrast, four strains of K. veneficum did not attack or affect the motility and survival of the copepods. Copepod immobilisation by the K. armiger strain was fast (within 15 min) and caused by attacks of swarming cells, likely through the transfer and action of a highly potent but uncharacterised neurotoxin. The copepods grazed and reproduced on a diet of K. armiger at densities below 1000 cells ml, but above 3500 cells ml À 1 the mixotrophic dinoflagellates immobilised, fed on and killed the copepods. Switching the trophic role of the microalgae from prey to predator of copepods couples population growth to reduced grazing pressure, promoting the persistence of blooms at high densities. K. armiger also fed on three other metazoan organisms offered, suggesting that active predation by mixotrophic dinoflagellates may be directly involved in causing mortalities at several trophic levels in the marine food web.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Marine microalgae attack and feed on metazoans

et al. 2012

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“…Here, we report the discovery of a gene for a voltage-gated proton channel in a dinoflagellate, Karlodinium veneficum (synonymous with Gymnodinium veneficum) (18), one of the few dinoflagellate species for which a sequence library is available. K. veneficum produces a variety of potent toxins (19,20) that facilitate its predatory lifestyle by immobilizing its prey (21).…”

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Voltage-gated proton channel in a dinoflagellate

Smith

Morgan

Musset

et al. 2011

Proc. Natl. Acad. Sci. U.S.A.

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Fogel and Hastings first hypothesized the existence of voltagegated proton channels in 1972 in bioluminescent dinoflagellates, where they were thought to trigger the flash by activating luciferase. Proton channel genes were subsequently identified in human, mouse, and Ciona intestinalis, but their existence in dinoflagellates remained unconfirmed. We identified a candidate proton channel gene from a Karlodinium veneficum cDNA library based on homology with known proton channel genes. K. veneficum is a predatory, nonbioluminescent dinoflagellate that produces toxins responsible for fish kills worldwide. Patch clamp studies on the heterologously expressed gene confirm that it codes for a genuine voltage-gated proton channel, kH V 1: it is proton-specific and activated by depolarization, its g H -V relationship shifts with changes in external or internal pH, and mutation of the selectivity filter (which we identify as Asp 51 ) results in loss of proton-specific conduction. Indirect evidence suggests that kH V 1 is monomeric, unlike other proton channels. Furthermore, kH V 1 differs from all known proton channels in activating well negative to the Nernst potential for protons, E H . This unique voltage dependence makes the dinoflagellate proton channel ideally suited to mediate the proton influx postulated to trigger bioluminescence. In contrast to vertebrate proton channels, whose main function is acid extrusion, we propose that proton channels in dinoflagellates have fundamentally different functions of signaling and excitability.ion selectivity | ion channel | permeation | channel gating | action potential

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“…The low R 2 = 0.29 value obtained from the linear relationship between cell numbers and RNA yields, maybe due to the low sample set (n = 36) of only one time point of 48 hours being available and the high standard deviations of RNA content per cell obtained from the individual K. veneficum strains. The type locality of its synonym, K. micrum, is cold temperate, and K. micrum has been reported from a broad geographic range in cold temperate waters in both hemispheres and in river habitats presumably exhibiting estuarine conditions (Bergholtz et al, 2005). It is unclear how many of these reports could represent a cryptic species because K. micrum is now a later synonym of K.…”

Section: An Unknown Microflagellate Was Isolated From a Fish Kill In mentioning

confidence: 99%

“…veneficum based on identical morphology and near identical rDNA LSU sequences (Bergholtz et al, 2005).…”

Section: An Unknown Microflagellate Was Isolated From a Fish Kill In mentioning

confidence: 99%

An evaluation of the applicability of microarrays for monitoring toxic algae in Irish coastal waters

McCoy

Touzet

Fleming

et al. 2012

Environ Sci Pollut Res

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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

Cited by 162 publications

References 34 publications

Marine microalgae attack and feed on metazoans

Marine microalgae attack and feed on metazoans

Voltage-gated proton channel in a dinoflagellate

An evaluation of the applicability of microarrays for monitoring toxic algae in Irish coastal waters

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