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B Reguera - One of the best experts on this subject based on the ideXlab platform.
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fine scale physical biological interactions during a shift from relaxation to upwelling with a focus on Dinophysis acuminata and its potential ciliate prey
Progress in Oceanography, 2019Co-Authors: Patricio A. Díaz, Pilar Riobo, M Ruizvillarreal, Beatriz Mourinocarballido, Concepcion Fernandezpena, B RegueraAbstract:Abstract Wind reversals and quick transitions from relaxation to upwelling in coastal areas cause major changes in water column structure, phytoplankton distribution and dominance, and rates of physiological processes. The cruise “ASIMUTH-Rias” (17–21 June 2013) was carried out in the Galician Rias and adjacent shelf, at the time of a DSP outbreak, to study small-scale physical processes associated with late spring blooms of D. acuminata and accompanying microzooplanktonic ciliates with the overall objective of improving predictive models of their occurrence. The cruise coincided with the initiation of an upwelling pulse following relaxation and deepening of a previously formed thin layer of diatoms. A 36-h cell cycle study carried on 18–20 June showed the vertical excursions of the thin layer, mainly delimited by the 13.5–14 °C isotherms and turbulence levels (e) of 10−8–10−6 m2 s−3, as well as marked changes in phytoplankton composition (increased density and dominance of diatoms). There was no evidence of daily vertical migration of D. acuminata, which remained in the top layer during the cycle study, but the opposite was observed in the ciliate populations. Dinophysis and its potential prey (Mesodinium species) cell maxima overlapped after midday, when the ciliate moved to the surface, suggesting an “ambush” strategy of Dinophysis to catch prey. A remarkable decline (from 0.65 to 0.33 d−1) in division rates (µ) of D. acuminata was associated with increased turbulence (e 2°C in about 8 h). In contrast, high division rates (µmin ∼ 0.69 d−1) persisted at a mid-shelf station where environmental conditions below the mixed layer were more stable. The onset of upwelling pulses appears to have a double negative effect on the net growth of Dinophysis populations: a direct physical effect due to advective dispersion and an indirect effect, decreased division rates. The latter would be caused by the rapid cooling of the mixed layer, and the increased turbulence at the surface resulting in shear stress to the cells. The short-term impact of upwelling pulses (and the winds promoting it) on the physiology of Dinophysis and its ciliate prey, and the role of mid-shelf populations of Dinophysis as a relatively undisturbed reservoir for the inoculation of subsequent blooms are discussed.
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comparative ecophysiology of Dinophysis acuminata and d acuta dinophyceae dinophysiales effect of light intensity and quality on growth cellular toxin content and photosynthesis
Journal of Phycology, 2018Co-Authors: Maria Garciaportela, B Reguera, Jose L Garrido, Pilar Riobo, Juan Blanco, Francisco RodriguezAbstract:Dinoflagellates of the genus Dinophysis are the most persistent producers of lipophilic shellfish toxins in Western Europe. Their mixotrophic nutrition requires a food chain of cryptophytes and plastid-bearing ciliates for sustained growth and photosynthesis. In this study, cultures of D. acuminata and D. acuta, their ciliate prey Mesodinium rubrum and the cryptophyte, Teleaulax amphioxeia, were subject to three experimental settings to study their physiological response to different combinations of light intensity and quality. Growth rates, pigment analyses (HPLC), photosynthetic parameters (PAM-fluorometry), and cellular toxin content (LC-MS) were determined. Specific differences in photosynthetic parameters were observed in Dinophysis exposed to different photon fluxes (10-650 μmol photons · m-2 · s-1 ), light quality (white, blue and green), and shifts in light regime. Dinophysis acuta was more susceptible to photodamage under high light intensities (370-650 μmol photons · m-2 · s-1 ) than D. acuminata but survived better with low light (10 μmol photons · m-2 · s-1 ) and to a prolonged period (28 d) of darkness. Mesodinium rubrum and T. amphioxeia showed their maximal growth rate and yield under white and high light whereas Dinophysis seemed better adapted to grow under green and blue light. Toxin analyses in Dinophysis showed maximal toxin per cell under high light after prey depletion at the late exponential-plateau phase. Changes observed in photosynthetic light curves of D. acuminata cultures after shifting light conditions from low intensity-blue light to high intensity-white light seemed compatible with photoacclimation in this species. Results obtained here are discussed in relation to different spatiotemporal distributions observed in field populations of D. acuminata and D. acuta in northwestern Iberia.
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notes on the cultivation of two mixotrophic Dinophysis species and their ciliate prey mesodinium rubrum
Toxins, 2018Co-Authors: Jorge Hernandezurcera, Pilar Rial, Maria Garciaportela, Patricia Loures, Jane Kilcoyne, Francisco Rodriguez, Amelia Fernandezvillamarin, B RegueraAbstract:Kleptoplastic mixotrophic species of the genus Dinophysis are cultured by feeding with the ciliate Mesodinium rubrum, itself a kleptoplastic mixotroph, that in turn feeds on cryptophytes of the Teleaulax/Plagioselmis/Geminigera (TPG) clade. Optimal culture media for phototrophic growth of D. acuminata and D. acuta from the Galician Rias (northwest Spain) and culture media and cryptophyte prey for M.rubrum from Huelva (southwest Spain) used to feed Dinophysis, were investigated. Phototrophic growth rates and yields were maximal when D. acuminata and D. acuta were grown in ammonia-containing K(-Si) medium versus f/2(-Si) or L1(-Si) media. Dinophysis acuminata cultures were scaled up to 18 L in a photobioreactor. Large differences in cell toxin quota were observed in the same Dinophysis strains under different experimental conditions. Yields and duration of exponential growth were maximal for M. rubrum from Huelva when fed Teleaulax amphioxeia from the same region, versus T. amphioxeia from the Galician Rias or T. minuta and Plagioselmis prolonga. Limitations for mass cultivation of northern Dinophysis strains with southern M. rubrum were overcome using more favorable (1:20) Dinophysis: Mesodinium ratios. These subtleties highlight the ciliate strain-specific response to prey and its importance to mass production of M. rubrum and Dinophysis cultures.
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seasonal variability of Dinophysis spp and protoceratium reticulatum associated to lipophilic shellfish toxins in a strongly stratified chilean fjord
Deep-sea Research Part Ii-topical Studies in Oceanography, 2014Co-Authors: Catharina Alvesdesouza, B Reguera, Pilar Riobo, Daniel Varela, Cristobal Contreras, Pablo De La Iglesia, Pamela A Fernandez, Byron Hipp, Cristina Hernandez, Jose M FrancoAbstract:Abstract The fine scale vertical distribution of Dinophysis spp. and Protoceratium reticulatum (potential producers of lipophilic shellfish toxins, LSTs) and its relation with LSTs in shellfish was studied in Reloncavi fjord, a strongly stratified system in Southern Chile. Samples were taken over two years from late spring to early autumn (2007–2008 period) and from early spring to late summer (2008–2009 period). Dinophysis spp., in particular Dinophysis acuminata, were always detected, often forming thin layers in the region of the salinity driven pycnocline, with cell maxima for D. acuminata of 28.5×103 cells L−1 in March 2008 and 17.1×103 cells L−1 in November 2008. During the 2008–2009 sampling period, blooms of D. acuminata co-occurred with high densities of cryptophyceans and the ciliate Mesodinium spp. The highest levels of pectenotoxin-2 (PTX-2; 2.2 ng L−1) were found in the plankton in February 2009, associated with moderate densities of D. acuminata, Dinophysis tripos and Dinophysis subcircularis (0.1–0.6×103 cells L−1). However, only trace levels of PTX-2 were observed in bivalves at that time. Dinophysistoxin (DTX-1 and DTX-3) levels in bivalves and densities of Dinophysis spp. were not well correlated. Low DTX levels in bivalves observed during a major bloom of D. acuminata in March 2008 suggested that there is a large seasonal intraspecific variability in toxin content of Dinophysis spp. driven by changes in population structure associated with distinct LST toxin profiles in Reloncavi fjord during the study period. A heterogeneous vertical distribution was also observed for P. reticulatum, whose presence was restricted to summer months. A bloom of this species of 2.2×103 cells L−1 at 14 m depth in February 2009 was positively correlated with high concentrations of yessotoxins in bivalves (51–496 ng g−1) and plankton samples (3.2 ng L−1). Our results suggest that a review of monitoring strategies for Dinophysis spp. in strongly stratified fjord systems should be carried out. They also indicate that early warning of LST events based on Dinophysis cell numbers are not reliable for seafood control.
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the growth season of Dinophysis acuminata in an upwelling system embayment a conceptual model based on in situ measurements
Deep-sea Research Part Ii-topical Studies in Oceanography, 2014Co-Authors: L Velosuarez, Yolanda Pazos, S Gonzalezgil, B RegueraAbstract:Abstract The distribution and physiological condition of the DSP-toxin producer Dinophysis acuminata, its relation with accompanying microplankton populations and coupling with upwelling events are described based on weekly sampling at a fixed station in Ria de Pontevedra, Galician Rias Baixas, NW Spain between March and December 2007. D. acuminata was detected from 18 June to 01 October. The appearance of D. acuminata in the Ria coincided with an upwelling-relaxation event and a short-lived maximum (up to 27 000 cells L−1) of its potential prey, the phototrophic ciliate Mesodinium cf rubrum. An increase in the proportion of vacuolated Dinophysis cells (72%) observed one week later suggests that the bloom was triggered by heterotrophic feeding on a co-occurring peak of Mesodinium coupled with advection of Dinophysis cells into the ria. Elevated frequencies of cells with starch and vacuoles were closely associated with the presence of M. cf rubrum during the entire bloom season. However, peaks in the frequency of vacuolated cells were only recorded on a few occasions, suggesting that D. acuminata is prey-limited most of the time but does not require a constant supply of prey for long term survival. Infection of D. acuminata by the parasite dinoflagellate Amoebophrya sp., a potential loss factor in the population dynamics of dinoflagellate populations, was observed (1–17% prevalence) immediately prior to the decline of the bloom. A conceptual model is presented of the mechanisms by which D. acuminata blooms develop in a ria influenced by upwelling which utilizes a combination of physics (upwelling-promoted shoreward transport of Dinophysis inoculum) and the match–mismatch of predator–prey (Dinophysis and Mesodinium) populations.
Francisco Rodriguez - One of the best experts on this subject based on the ideXlab platform.
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notes on the cultivation of two mixotrophic Dinophysis species and their ciliate prey mesodinium rubrum
Toxins, 2018Co-Authors: Jorge Hernandezurcera, Pilar Rial, Maria Garciaportela, Patricia Loures, Jane Kilcoyne, Francisco Rodriguez, Amelia Fernandezvillamarin, B RegueraAbstract:Kleptoplastic mixotrophic species of the genus Dinophysis are cultured by feeding with the ciliate Mesodinium rubrum, itself a kleptoplastic mixotroph, that in turn feeds on cryptophytes of the Teleaulax/Plagioselmis/Geminigera (TPG) clade. Optimal culture media for phototrophic growth of D. acuminata and D. acuta from the Galician Rias (northwest Spain) and culture media and cryptophyte prey for M.rubrum from Huelva (southwest Spain) used to feed Dinophysis, were investigated. Phototrophic growth rates and yields were maximal when D. acuminata and D. acuta were grown in ammonia-containing K(-Si) medium versus f/2(-Si) or L1(-Si) media. Dinophysis acuminata cultures were scaled up to 18 L in a photobioreactor. Large differences in cell toxin quota were observed in the same Dinophysis strains under different experimental conditions. Yields and duration of exponential growth were maximal for M. rubrum from Huelva when fed Teleaulax amphioxeia from the same region, versus T. amphioxeia from the Galician Rias or T. minuta and Plagioselmis prolonga. Limitations for mass cultivation of northern Dinophysis strains with southern M. rubrum were overcome using more favorable (1:20) Dinophysis: Mesodinium ratios. These subtleties highlight the ciliate strain-specific response to prey and its importance to mass production of M. rubrum and Dinophysis cultures.
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comparative ecophysiology of Dinophysis acuminata and d acuta dinophyceae dinophysiales effect of light intensity and quality on growth cellular toxin content and photosynthesis
Journal of Phycology, 2018Co-Authors: Maria Garciaportela, B Reguera, Jose L Garrido, Pilar Riobo, Juan Blanco, Francisco RodriguezAbstract:Dinoflagellates of the genus Dinophysis are the most persistent producers of lipophilic shellfish toxins in Western Europe. Their mixotrophic nutrition requires a food chain of cryptophytes and plastid-bearing ciliates for sustained growth and photosynthesis. In this study, cultures of D. acuminata and D. acuta, their ciliate prey Mesodinium rubrum and the cryptophyte, Teleaulax amphioxeia, were subject to three experimental settings to study their physiological response to different combinations of light intensity and quality. Growth rates, pigment analyses (HPLC), photosynthetic parameters (PAM-fluorometry), and cellular toxin content (LC-MS) were determined. Specific differences in photosynthetic parameters were observed in Dinophysis exposed to different photon fluxes (10-650 μmol photons · m-2 · s-1 ), light quality (white, blue and green), and shifts in light regime. Dinophysis acuta was more susceptible to photodamage under high light intensities (370-650 μmol photons · m-2 · s-1 ) than D. acuminata but survived better with low light (10 μmol photons · m-2 · s-1 ) and to a prolonged period (28 d) of darkness. Mesodinium rubrum and T. amphioxeia showed their maximal growth rate and yield under white and high light whereas Dinophysis seemed better adapted to grow under green and blue light. Toxin analyses in Dinophysis showed maximal toxin per cell under high light after prey depletion at the late exponential-plateau phase. Changes observed in photosynthetic light curves of D. acuminata cultures after shifting light conditions from low intensity-blue light to high intensity-white light seemed compatible with photoacclimation in this species. Results obtained here are discussed in relation to different spatiotemporal distributions observed in field populations of D. acuminata and D. acuta in northwestern Iberia.
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Dinophysis toxins causative organisms distribution and fate in shellfish
Marine Drugs, 2014Co-Authors: B Reguera, Gemita Pizarro, Francisco Rodriguez, Pilar Riobo, Jose M Franco, Patricio A. Díaz, Juan A BlancoAbstract:Several Dinophysis species produce diarrhoetic toxins (okadaic acid and Dinophysistoxins) and pectenotoxins, and cause gastointestinal illness, Diarrhetic Shellfish Poisoning (DSP), even at low cell densities (<103 cells·L−1). They are the main threat, in terms of days of harvesting bans, to aquaculture in Northern Japan, Chile, and Europe. Toxicity and toxin profiles are very variable, more between strains than species. The distribution of DSP events mirrors that of shellfish production areas that have implemented toxin regulations, otherwise misinterpreted as bacterial or viral contamination. Field observations and laboratory experiments have shown that most of the toxins produced by Dinophysis are released into the medium, raising questions about the ecological role of extracelular toxins and their potential uptake by shellfish. Shellfish contamination results from a complex balance between food selection, adsorption, species-specific enzymatic transformations, and allometric processes. Highest risk areas are those combining Dinophysis strains with high cell content of okadaates, aquaculture with predominance of mytilids (good accumulators of toxins), and consumers who frequently include mussels in their diet. Regions including pectenotoxins in their regulated phycotoxins will suffer from much longer harvesting bans and from disloyal competition with production areas where these toxins have been deregulated.
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first report of the toxin profile of Dinophysis sacculus stein from lc ms analysis of laboratory cultures
Toxicon, 2013Co-Authors: Pilar Riobo, B Reguera, Jose M Franco, Francisco RodriguezAbstract:Dinophysis sacculus is associated with DSP outbreaks especially in the Mediterranean Sea and is supposed to be mildly toxic based on few toxin results from field samples. First report of LC-MS analysis of D. sacculus cultures from Galicia (NW Spain) showed moderate amounts of OA (7.8 pg cell � 1 ) comparable to those found in Dinophysis acuminata from the same region, PTX2 (13.2 pg cell � 1 ) and trace amounts of DTX1 (0.8 pg OA equiv. cell � 1 ). The contribution of D. sacculus to DSP outbreaks in the Galician Northern Rias should not be underestimated.
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Molecular probes and microarrays for the detection of toxic algae in the genera Dinophysis and Phalacroma (Dinophyta)
Environmental Science and Pollution Research, 2013Co-Authors: Bente Edvardsen, Laura Escalera, B Reguera, Francisco Rodriguez, Simon M. Dittami, René Groben, Sissel Brubak, Jixin Chen, Linda K. MedlinAbstract:Dinophysis and Phalacroma species containing diarrheic shellfish toxins and pectenotoxins occur in coastal temperate waters all year round and prevent the harvesting of mussels during several months each year in regions in Europe, Chile, Japan, and New Zealand. Toxicity varies among morphologically similar species, and a precise identification is needed for early warning systems. Molecular techniques using ribosomal DNA sequences offer a means to identify and detect precisely the potentially toxic species. We designed molecular probes targeting the 18S rDNA at the family and genus levels for Dinophysis and Phalacroma and at the species level for Dinophysis acuminata , Dinophysis acuta , and Dinophysis norvegica , the most commonly occurring, potentially toxic species of these genera in Western European waters. Dot blot hybridizations with polymerase chain reaction (PCR)-amplified rDNA from 17 microalgae were used to demonstrate probe specificity. The probes were modified along with other published fluorescence in situ hybridization and PCR probes and tested for a microarray platform within the MIDTAL project ( http://www.midtal.com ). The microarray was applied to field samples from Norway and Spain and compared to microscopic cell counts. These probes may be useful for early warning systems and monitoring and can also be used in population dynamic studies to distinguish species and life cycle stages, such as cysts, and their distribution in time and space.
Myung Gil Park - One of the best experts on this subject based on the ideXlab platform.
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Dinophysis caudata dinophyceae sequesters and retains plastids from the mixotrophic ciliate prey mesodinium rubrum 1
Journal of Phycology, 2012Co-Authors: Woongghi Shin, Wayne D Coats, Myung Gil ParkAbstract:"Phototrophic"Dinophysis Ehrenberg species are well known to have chloroplasts of a cryptophyte origin, more specifically of the cryptophyte genus complex Teleaulax/Geminigera. Nonetheless, whether chloroplasts of "phototrophic"Dinophysis are permanent plastids or periodically derived kleptoplastids (stolen chloroplasts) has not been confirmed. Indeed, molecular sequence data and ultrastructural data lead to contradictory interpretations about the status of Dinophysis plastids. Here, we used established cultures of D. caudata strain DC-LOHABE01 and M. rubrum strain MR-MAL01 to address the status of Dinophysis plastids. Our approach was to experimentally generate D. caudata with "green" plastids and then follow the ingestion and fate of "reddish-brown" prey plastids using light microscopy, time-lapse videography, and single-cell TEM. Our results for D. caudata resolve the apparent discrepancy between morphological and molecular data by showing that plastids acquired when feeding on M. rubrum are structurally modified and retained as stellate compound chloroplasts characteristic of Dinophysis species.
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the marine dinoflagellate genus Dinophysis can retain plastids of multiple algal origins at the same time
Harmful Algae, 2012Co-Authors: Myung Gil ParkAbstract:The ‘phototrophic’ Dinophysis Ehrenberg species are well known to have plastids of a cryptophyte origin, more specifically cryptophyte genus complex Teleaulax/Geminigera. However, how often the phototrophic Dinophysis could retain both types of plastids from this genus complex at the same time in a cell and also whether the phototrophic cells could retain plastids of the other algal origins rather than cryptophyte have not been investigated in detail. We isolated a total of 67 phototrophic Dinophysis spp. cells between May 2008 and September 2009 along western and southern coasts of Korea and amplified psbA as a tracer to investigate plastid diversity from the isolated cells. Then, the PCR products were digested with a restriction enzyme, SfaNI, to distinguish between the most common Teleaulax amphioxeia-type and the less common T. acuta-type plastids. During this study, we sometimes encountered ‘green’ Dinophysis acuminata cells, which contained varying degree of red autofluorescencing green plastids inside the cell, along together typical orange autofluorescencing reddish-brown plastids. The RFLP patterns of the PCR products digested by SfaNI revealed that a total of 66 Dinophysis cells analyzed in this study all contained T. amphioxeia-type plastid. Further, approximately two-thirds of the analyzed Dinophysis cells contained both T. amphioxeia-type and T. acuta-type plastids at the same time in a single cell. Interestingly, SfaNI digestion of the products amplified on psbA gene from 10 Dinophysis cells produced a different RFLP pattern: in addition to T. amphioxeia-type and sometimes T. acuta-type plastid, undigested fragments occurred. We cloned the PCR products and determined psbA gene sequences from the cells containing undigested fragments with SfaNI. Surprisingly, these Dinophysis cells contained even three (i.e. cryptophytes T. amphioxeia and T. acuta and raphidophyte Heterosigma akashiwo) or four (i.e. cryptophytes T. amphioxeia and T. acuta, raphidophyte H. akashiwo, and chlorophyte Pyramimonas sp.) different plastid sequences at the same time in a single cell. Our result indicates that besides the sole prey Mesodinium rubrum (=Myrionecta rubra) known until now, there may be other potential prey organisms, presumably the plastid-retaining ciliates, from which phototrophic Dinophysis may acquire plastids of several algal origins other than cryptophyte.
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does Dinophysis caudata dinophyceae have permanent plastids
Journal of Phycology, 2010Co-Authors: Myung Gil ParkAbstract:The marine photosynthetic dinoflagellates Dinophysis Ehrenb. species are obligate mixotrophs that require both light and the ciliate prey Myrionecta rubra (= Mesodinium rubrum) for long-term survival. Despite rapid progress on the study of Dinophysis using laboratory cultures, however, whether it has its own permanent plastids or kleptoplastids (i.e., stolen plastids from its ciliate prey) is not fully resolved. Here, we addressed this issue using established cultures of D. caudata Saville-Kent strain DC-LOHABE01 and cross-feeding/starvation experiments encompassing the prey M. rubra strain MR-MAL01 cultures grown on two different cryptophytes (strains CR-MAL01 and CR-MAL11). To follow the fate of prey plastids, psbA gene as a tracer was amplified from individually isolated D. caudata cells, and the PCR products were digested with a restriction enzyme, SfaNI. The RFLP pattern of the PCR products digested by SfaNI revealed that D. caudata continued to keep CR-MAL01–type plastids, while it lost CR-MAL11–type plastids with increasing starvation time. Our results suggest that Dinophysis treats in different ways plastids taken up from different cryptophytes via its ciliate prey M. rubra. Alternatively, D. caudata may already have its own CR-MAL01–type permanent plastid, with two types of plastids (CR-MAL01 and CR-MAL11) obtained from M. rubra being lost within 1 month. This result highlights the need to identify more accurately the origin of plastids in newly isolated photosynthetic Dinophysis species to resolve the issue of plastid permanence.
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growth and grazing responses of the mixotrophic dinoflagellate Dinophysis acuminata as functions of light intensity and prey concentration
Aquatic Microbial Ecology, 2008Co-Authors: Yi Gu Kang, Wayne D Coats, Myung Gil ParkAbstract:Dinophysis acuminata, a photosynthetic marine dinoflagellate, possesses plastids of cryptophyte origin and causes diarrhetic shellfish poisoning (DSP). Recent work has shown D. acumi- nata to be a mixotroph that grows well when feeding on the photosynthetic ciliate Myrionecta rubra. Using established cultures, we examined the effects of light intensity and prey (M. rubra) concentra- tion on growth and ingestion rates of D. acuminata. Growth rates increased with increasing prey concentration under continuous illumination of 60 μE m -2 s -1 , with maximum mixotrophic growth (0.91 d -1 ) almost 5 times higher than growth in the absence of prey (0.19 d -1 ). The maximum inges- tion rate of D. acuminata was 1296 pg C Dinophysis -1 d -1 (3.2 M. rubra cells Dinophysis -1 d -1 ) for data fitted to a Michaelis-Menten equation. Growth rate also increased with increasing light intensity, an effect even stronger when prey was supplied. Increased growth with increasing irradiance was accompanied by a corresponding increase in ingestion. While D. acuminata continued to grow in semi-continuous food-replete cultures at high (200 μE m -2 s -1 ) and low (10 μE m -2 s -1 ) light intensity, it failed to grow in darkness, despite the presence of prey. Our results suggest that D. acuminata is an obligate mixotroph that requires both light and prey for long-term survival. Results indicate that Dinophysis species are typically prey-limited in the field.
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first successful culture of the marine dinoflagellate Dinophysis acuminata
Aquatic Microbial Ecology, 2006Co-Authors: Myung Gil Park, Geumog Myung, Yi Gu KangAbstract:The dinoflagellate genus Dinophysis in- cludes several species that cause diarrhetic shellfish poi- soning, none of which have yet been established in cul- ture. We report on the maintenance of Dinophysis acuminata cultures that were established in December 2005 and also on its feeding mechanism, and growth rates when fed the ciliate prey Myrionecta rubra with and without the addition of the cryptophyte Teleaulax sp. D. acuminata grew well (growth rate of 0.95 d -1 ) in laboratory culture when supplied with the marine ciliate M. rubra as prey, reaching a maximum concentration of about 2400 cells ml -1 at the end of the feeding experiment. In contrast, D. acuminata did not show sustained growth in the absence of the ciliate or when provided the cryptophyte Teleaulax sp. as prey (D. acuminata used its peduncle to extract the cell contents of the prey organism, M. rubra). Based on the prey- preda- tor interactions occurring among D. acuminata, M. rubra, and Teleaulax sp. in this study, establishment of perma- nent culture of the dinoflagellate D. acuminata may facil- itate a better understanding of the ecophysiology, biol- ogy, and toxicology of Dinophysis species, as well as the evolution of dinoflagellate plastids.
B Reguera - One of the best experts on this subject based on the ideXlab platform.
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Genetic variability and molecular phylogeny of Dinophysis species (Dinophyceae) from single cell analysis of mitocondrial cox1 gene.
2020Co-Authors: Nicolas Raho, B Reguera, F. Rodríguez, Irma MarínAbstract:The identification of Dinophysis spp. is a crucial task in harmful algae monitoring programmes due to the occurrence of several toxin producer species responsible for diarrethic shellfish poisoning (DSP) events. The morphological variability exhibited by some Dinophysis species, as those in the D. acuminata-complex makes difficult its identification in field samples. Other taxonomic methods, such as molecular analyses based on ribosomal genes and intergenic regions (ITS), display limited resolution in the genus Dinophysis due to their low inter-specific variability. In the present study we explore the potential of cox1 gene as a marker to differentiate among Dinophysis species, based on previous findings of high resolution for two morphological similar species, D. acuminata and D. ovum.
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Effects of small-scale turbulence on two species of Dinophysis
Harmful Algae, 2019Co-Authors: María García-portela, B Reguera, Francisco B. Rodriguez, Maurizio Ribera D'alcalà, Marina MontresorAbstract:Abstract Dinoflagellate species of Dinophysis, in particular D. acuminata and D. acuta, produce lipophilic toxins that pose a threat to human health when concentrated in shellfish and jeopardize shellfish exploitations in western Europe. In northwestern Iberia, D. acuminata has a long growing season, from spring to early autumn, and populations develop as soon as shallow stratification forms when the upwelling season begins. In contrast, D. acuta blooms in late summer, when the depth of the pycnocline is maximal and upwelling pulses are moderate. In situ observations on the hydrodynamic regimes during the two windows of opportunity for Dinophysis species led us to hypothesize that D. acuta should be more sensitive to turbulence than D. acuminata. To test this hypothesis, we studied the response of D. acuminata and D. acuta to three realistic turbulence levels low (LT), e ≈ 10−6 m2 s-3; medium (MT), e ≈ 10-5 m2 s-3 and high (HT), e ≈ 10-4 m2 s-3 generated by Turbogen, a highly reproducible, computer-controlled system. Cells of both species exposed to LT and MT grew at rates similar to the controls. Marked differences were found in the response to HT: D. acuminata grew slowly after an initial lag phase, whereas D. acuta cell numbers declined. Results from this study support the hypothesis that turbulence may play a role in shaping the spatio-temporal distribution of individual species of Dinophysis. We also hypothesize that, in addition to cell disturbance affecting division, sustained high shear generated by microturbulence may cause a decline in Dinophysis numbers due to decreased densities of ciliate prey.
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Mesoscale Dynamics and Niche Segregation of Two Dinophysis Species in Galician-Portuguese Coastal Waters
Toxins, 2019Co-Authors: Patricio A. Díaz, B Reguera, Teresa Moita, Isabel Bravo, Manuel Ruiz-villarreal, Santiago FragaAbstract:Blooms of Dinophysis acuminata occur every year in Galicia (northwest Spain), between spring and autumn. These blooms contaminate shellfish with lipophilic toxins and cause lengthy harvesting bans. They are often followed by short-lived blooms of Dinophysis acuta, associated with northward longshore transport, at the end of the upwelling season. During the summers of 1989 and 1990, dense blooms of D. acuta developed in situ, initially co-occurring with D. acuminata and later with the paralytic shellfish toxin-producer Gymnodinium catenatum. Unexplored data from three cruises carried out before, during, and following autumn blooms (13⁻14, 27⁻28 September and 11⁻12 October) in 1990 showed D. acuta distribution in shelf waters within the 50 m and 130 m isobaths, delimited by the upwelling front. A joint review of monitoring data from Galicia and Portugal provided a mesoscale view of anomalies in SST and other hydroclimatic factors associated with a northward displacement of the center of gravity of D. acuta populations. At the microscale, re-examination of the vertical segregation of cell maxima in the light of current knowledge, improved our understanding of niche differentiation between the two species of Dinophysis. Results here improve local transport models and forecast of Dinophysis events, the main cause of shellfish harvesting bans in the most important mussel production area in Europe.
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Metabolomic Profiles of Dinophysis acuminata and Dinophysis acuta Using Non-Targeted High-Resolution Mass Spectrometry: Effect of Nutritional Status and Prey
Marine Drugs, 2018Co-Authors: María García-portela, B Reguera, Francisco J. Rodriguez, Manoella Sibat, Andreas Altenburger, Philipp HessAbstract:Photosynthetic species of the genus Dinophysis are obligate mixotrophs with temporary plastids (kleptoplastids) that are acquired from the ciliate Mesodinium rubrum, which feeds on cryptophytes of the Teleaulax-Plagioselmis-Geminigera clade. A metabolomic study of the three-species food chain Dinophysis-Mesodinium-Teleaulax was carried out using mass spectrometric analysis of extracts of batch-cultured cells of each level of that food chain. The main goal was to compare the metabolomic expression of Galician strains of Dinophysis acuminata and D. acuta that were subjected to different feeding regimes (well-fed and prey-limited) and feeding on two Mesodinium (Spanish and Danish) strains. Both Dinophysis species were able to grow while feeding on both Mesodinium strains, although differences in growth rates were observed. Toxin and metabolomic profiles of the two Dinophysis species were significantly different, and also varied between different feeding regimes and different prey organisms. Furthermore, significantly different metabolomes were expressed by a strain of D. acuminata that was feeding on different strains of the ciliate Mesodinium rubrum. Both species-specific metabolites and those common to D. acuminata and D. acuta were tentatively identified by screening of METLIN and Marine Natural Products Dictionary databases. This first metabolomic study applied to Dinophysis acuminata and D.acuta in culture establishes a basis for the chemical inventory of these species.
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Origin of cryptophyte plastids in Dinophysis from Galician waters: results from field and culture experiments
Aquatic Microbial Ecology, 2015Co-Authors: Pilar Rial, Nicolas Raho, B Reguera, Aitor Laza-martínez, Francisco B. RodriguezAbstract:Photosynthetic species of the dinoflagellate genus Dinophysis retain cryptophyte plastids from the Teleaulax/Plagioselmis/Geminigera group via their ciliate prey Mesodinium rubrum, but other cryptophyte and algal sources have occasionally been found. Identifying the specific prey of ciliates fed upon by mixotrophic Dinophysis species is a requisite to improve predictive capabilities of their bloom formation. Here we examined the origin of Dinophysis plastids from Galician waters and their transfer in cross-feeding experiments in the laboratory. Plastid 23S rDNA sequences were obtained from 60 Dinophysis specimens from the Galician Rías Baixas and shelf waters. Most sequences in Dinophysis cells were identical to Teleaulax amphioxeia. Galician shelf samples also yielded T. amphioxeia-type sequences, although one of these was closer to a freshwater cryptophyte, and a few others were related with other taxa (diatoms, red algae and proteobacteria). Mesodinium cf. major, an alternative prey to M. rubrum, was identified. Cross-feeding tests in the laboratory showed that T. amphioxeia, T. minuta, T. gracilis, and Plagioselmis prolonga sustained growth of M. rubrum. D. acuminata cultivated on a M. rubrum–T. amphioxeia system was transferred to M. rubrum fed upon T. minuta, T. gracilis and P. prolonga. After >2 mo of acclimation, T. amphioxeia plastid 23S rDNA and psbA gene sequences from D. acuminata were replaced by those of secondary cryptophytes. Here we confirm 2 cryptophytes, T. minuta and P. prolonga, as suitable prey for M. rubrum. Nevertheless, field and laboratory results show that, at least for D. acuminata, T. amphioxeia represents the main source of plastids.Versión del edito
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Dinophysis norvegica dinophyceae more a predator than a producer
Harmful Algae, 2008Co-Authors: Wanderson Fernandes De Carvalho, Susanna Minnhagen, Edna GraneliAbstract:Several studies have proved that some Dinophysis species are capable of ingesting particulate organic matter besides of being photosynthetic, a form of nutrition termed mixotrophy. Phagotrophy may be an important aspect of the life history of the genus Dinophysis and the key to understand its ecology. We used modern techniques coupling flow cytometry and acidotropic probes to detect and score food vacuolated Dinophysis norvegica cells in natural samples. In addition, feeding experiments were conduced under controlled conditions to observe if D. norvegica would grow feeding on the cryptophyte Teleaulax amphioxeia. The results of the field observations showed a frequency of phagotrophy between 25 and 71% in a natural D. norvegica population from the Baltic Sea, which is higher than previous reports (1–20%). Although molecular methods have proved that the kleptoplastids of the D. norvegica from the Baltic Sea are from T. amphioxeia, the laboratory experiments showed that the presence of T. amphioxeia in the cultures did not enhance the survival rate of D. norvegica neither in phototrophic nor in heterotrophic conditions. We suggest that the D. norvegica Kleptoplats are obtained through a heterotrophic or mixotrophic protist, which have been feeding on cryptophytes, as it has recently been shown for Dinophysis acuminata. Our main conclusion is that D. norvegica, and probably all other species from the genus Dinophysis, is mainly phagotrophic and feeds on a larger prey than T. amphioxeia. Autotrophy through kleptoplastidy would be a secondary feature used as a complementary or short-term survival strategy.
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okadaic acid accumulation in macrofilter feeders subjected to natural blooms of Dinophysis acuminata
Harmful Algae, 2008Co-Authors: S Reizopoulou, Evangelia Strogyloudi, Antonia Giannakourou, Kalliopi Pagou, I Hatzianestis, Christina Pyrgaki, Edna GraneliAbstract:Okadaic acid accumulation in macrofilter-feeders subjected to natural blooms of Dinophysis acuminata
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food selectivity and grazing impact on toxic Dinophysis spp by copepods feeding on natural plankton assemblages
Harmful Algae, 2006Co-Authors: Betina Kozlowskysuzuki, Per Carlsson, Alexander Ruhl, Edna GraneliAbstract:Food selectivity and grazing impact by Acartia bifilosa, Temora longicornis and Centropages typicus on Dinophysis spp. plankton assemblages were experimentally investigated in the Baltic Sea. Toxin analyses were carried out on phyto- and zooplankton-dominated size fractions from field-collected samples to assess if toxins produced by Dinophysis spp. would end up in the zooplankton. All copepod species fed,actively on toxic Dinophysis spp. (Dinophysis acuta and Dinophysis norvegica). Despite the non-selective feeding behaviour by T longicornis and C. typicus, selectivity coefficients on D. acuta progressively decreased as food availability increased. Similar response was not observed for A. bifilosa, which displayed an even less selective behaviour. A. bifilosa had no significant negative effect on the net growth of D. norvegica at the lowest food concentration offered, whereas T longicornis and C typicus had significant negative effects on the net growth of D. acuta at low concentrations, similar to those observed in situ. Both species could potentially contribute as a substantial loss factor for Dinophysis spp. provided they are abundant at the onset of the blooms. The estimated grazing impact by the copepod populations was only considerable when C typicus abundance was high and D. acuta population in sharp decline. Our results suggest that when high abundance of grazers and poor growth condition of prey populations prevail, grazing impact by copepods can contribute considerably to prevent Dinophysis spp. populations to grow or to cause the populations to decline. Okadaic acid was detected in the zooplankton size fraction at one occasion, but the concentration was far lower than the one expected from the ingested toxins. Thus, even if copepods may act as vectors of DSP-toxins to higher trophic levels, the amount of these toxins transported in the food web by copepods seems limited. (C) 2005 Elsevier B.V. All rights reserved. (Less)
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genetic analysis of the psba gene from single cells indicates a cryptomonad origin of the plastid in Dinophysis dinophyceae
Phycologia, 2003Co-Authors: Sven Janson, Edna GraneliAbstract:Genetic analyses of the psbA gene from single cells indicates a cryptomonad origin of the plastid in Dinophysis (Dinophyceae)
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Light and dark carbon uptake by Dinophysis species in comparison to other photosynthetic and heterotrophic dinoflagellates
Aquatic Microbial Ecology, 1997Co-Authors: Edna Graneli, Per Carlsson, Donald M Anderson, Serge Y. MaestriniAbstract:Light and dark carbon uptake by Dinophysis species in comparison to other photosynthetic and heterotrophic dinoflagellates