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Garric S, Ratin M, Marie D, Foulon V, Probert I, Rodriguez F, Six C. Impaired photoacclimation in a kleptoplastidic dinoflagellate reveals physiological limits of early stages of endosymbiosis. Curr Biol 2024; 34:3064-3076.e5. [PMID: 38936366 DOI: 10.1016/j.cub.2024.05.066] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2024] [Revised: 04/02/2024] [Accepted: 05/29/2024] [Indexed: 06/29/2024]
Abstract
Dinophysis dinoflagellates are predators of Mesodinium ciliates, from which they retain only the plastids of cryptophyte origin. The absence of nuclear photosynthetic cryptophyte genes in Dinophysis raises intriguing physiological and evolutionary questions regarding the functional dynamics of these temporary kleptoplastids within a foreign cellular environment. In an experimental setup including two light conditions, the comparative analysis with Mesodinium rubrum and the cryptophyte Teleaulax amphioxeia revealed that Dinophysis acuminata possessed a smaller and less dynamic functional photosynthetic antenna for green light, a function performed by phycoerythrin. We showed that the lack of the cryptophyte nucleus prevented the synthesis of the phycoerythrin α subunit, thereby hindering the formation of a complete phycoerythrin in Dinophysis. In particular, biochemical analyses showed that Dinophysis acuminata synthesized a poorly stable, incomplete phycoerythrin composed of chromophorylated β subunits, with impaired performance. We show that, consequently, a continuous supply of new plastids is crucial for growth and effective photoacclimation in this organism. Transcriptome analyses revealed that all examined strains of Dinophysis spp. have acquired the cryptophyte pebA and pebB genes through horizontal gene transfer, suggesting a potential ability to synthesize the phycobilin pigments bound to the cryptophyte phycoerythrin. By emphasizing that a potential long-term acquisition of the cryptophyte plastid relies on establishing genetic independence for essential functions such as light harvesting, this study highlights the intricate molecular challenges inherent in the enslavement of organelles and the processes involved in the diversification of photosynthetic organisms through endosymbiosis.
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Affiliation(s)
- Sarah Garric
- Sorbonne Université, Centre National de la Recherche Scientifique, UMR 7144, Adaptation et Diversité en Milieu Marin, group Ecology of Marine Plankton, Station Biologique de Roscoff, Place Georges Teissier, Roscoff 29680, France
| | - Morgane Ratin
- Sorbonne Université, Centre National de la Recherche Scientifique, UMR 7144, Adaptation et Diversité en Milieu Marin, group Ecology of Marine Plankton, Station Biologique de Roscoff, Place Georges Teissier, Roscoff 29680, France
| | - Dominique Marie
- Sorbonne Université, Centre National de la Recherche Scientifique, UMR 7144, Adaptation et Diversité en Milieu Marin, group Ecology of Marine Plankton, Station Biologique de Roscoff, Place Georges Teissier, Roscoff 29680, France
| | - Valentin Foulon
- Centre National de la Recherche Scientifique, UMR 6285 Laboratoire des Sciences et Techniques de l'information de la Communication et de la Connaissance (Lab-STICC), Technopole Brest-Iroise, Brest 29238, France
| | - Ian Probert
- Sorbonne Université, FR 2424, Station Biologique de Roscoff, Place Georges Teissier, Roscoff 29680, France
| | - Francisco Rodriguez
- Centro oceanográfico de Vigo (IEO-CSIC), Subida a Radio Faro 50, Vigo 36390, Spain
| | - Christophe Six
- Sorbonne Université, Centre National de la Recherche Scientifique, UMR 7144, Adaptation et Diversité en Milieu Marin, group Ecology of Marine Plankton, Station Biologique de Roscoff, Place Georges Teissier, Roscoff 29680, France.
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Ayache N, Campbell L, Gobler CJ, Smith JL. Photoacclimation and photophysiology of four species of toxigenic Dinophysis. HARMFUL ALGAE 2024; 136:102624. [PMID: 38876524 DOI: 10.1016/j.hal.2024.102624] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/11/2024] [Revised: 03/27/2024] [Accepted: 04/02/2024] [Indexed: 06/16/2024]
Abstract
This study aimed to explore the effects of different light intensities on the ecophysiology of eight new Dinophysis isolates comprising four species (D. acuminata, D. ovum, D. fortii, and D. caudata) collected from different geographical regions in the US. After six months of acclimation, the growth rates, photosynthetic efficiency (Fv/Fm ratio), toxin content, and net toxin production rates of the Dinophysis strains were examined. The growth rates of D. acuminata and D. ovum isolates were comparable across light intensities, with the exception of one D. acuminata strain (DANY1) that was unable to grow at the lowest light intensity. However, D. fortii and D. caudata strains were photoinhibited and grew at a slower rate at the highest light intensity, indicating a lower degree of adaptability and tolerance to such conditions. Photosynthetic efficiency was similar for all Dinophysis isolates and negatively correlated with exposure to high light intensities. Multiple toxin metrics, including cellular toxin content and net production rates of DSTs and PTXs, were variable among species and even among isolates of the same species in response to light intensity. A pattern was detected, however, whereby the net production rates of PTXs were significantly lower across all Dinophysis isolates when exposed to the lowest light intensity. These findings provide a basis for understanding the effects of light intensity on the eco-physiological characteristics of Dinophysis species in the US and could be employed to develop integrated physical-biological models for species and strains of interest to predict their population dynamics and mitigate their negative effects.
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Affiliation(s)
- Nour Ayache
- Virginia Institute of Marine Science, William & Mary, Gloucester Point, VA 23062, USA
| | - Lisa Campbell
- Department of Oceanography and Department of Biology, Texas A&M University, College Station, Texas 77843, USA
| | - Christopher J Gobler
- School of Marine and Atmospheric Sciences, Stony Brook University, Southampton, NY 11968, USA
| | - Juliette L Smith
- Virginia Institute of Marine Science, William & Mary, Gloucester Point, VA 23062, USA.
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Miyagishima SY. Taming the perils of photosynthesis by eukaryotes: constraints on endosymbiotic evolution in aquatic ecosystems. Commun Biol 2023; 6:1150. [PMID: 37952050 PMCID: PMC10640588 DOI: 10.1038/s42003-023-05544-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2023] [Accepted: 11/03/2023] [Indexed: 11/14/2023] Open
Abstract
An ancestral eukaryote acquired photosynthesis by genetically integrating a cyanobacterial endosymbiont as the chloroplast. The chloroplast was then further integrated into many other eukaryotic lineages through secondary endosymbiotic events of unicellular eukaryotic algae. While photosynthesis enables autotrophy, it also generates reactive oxygen species that can cause oxidative stress. To mitigate the stress, photosynthetic eukaryotes employ various mechanisms, including regulating chloroplast light absorption and repairing or removing damaged chloroplasts by sensing light and photosynthetic status. Recent studies have shown that, besides algae and plants with innate chloroplasts, several lineages of numerous unicellular eukaryotes engage in acquired phototrophy by hosting algal endosymbionts or by transiently utilizing chloroplasts sequestrated from algal prey in aquatic ecosystems. In addition, it has become evident that unicellular organisms engaged in acquired phototrophy, as well as those that feed on algae, have also developed mechanisms to cope with photosynthetic oxidative stress. These mechanisms are limited but similar to those employed by algae and plants. Thus, there appear to be constraints on the evolution of those mechanisms, which likely began by incorporating photosynthetic cells before the establishment of chloroplasts by extending preexisting mechanisms to cope with oxidative stress originating from mitochondrial respiration and acquiring new mechanisms.
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Affiliation(s)
- Shin-Ya Miyagishima
- Department of Gene Function and Phenomics, National Institute of Genetics, 1111 Yata, Mishima, Shizuoka, 411-8540, Japan.
- The Graduate University for Advanced Studies, SOKENDAI, 1111 Yata, Mishima, Shizuoka, 411-8540, Japan.
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Abstract
Kleptoplasty, the process by which a host organism sequesters and retains algal chloroplasts, is relatively common in protists. The origin of the plastid varies, as do the length of time it is retained in the host and the functionality of the association. In metazoa, the capacity for long-term (several weeks to months) maintenance of photosynthetically active chloroplasts is a unique characteristic of a handful of sacoglossan sea slugs. This capability has earned these slugs the epithets "crawling leaves" and "solar-powered sea slugs." This Unsolved Mystery explores the basis of chloroplast maintenance and function and attempts to clarify contradictory results in the published literature. We address some of the mysteries of this remarkable association. Why are functional chloroplasts retained? And how is the function of stolen chloroplasts maintained without the support of the algal nucleus?
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Ferreira GD, Figueira J, Marques SC, Hansen PJ, Calbet A. The strengths and weaknesses of Live Fluorescently Labelled Algae (LFLA) to estimate herbivory in protozooplankton and mixoplankton. MARINE ENVIRONMENTAL RESEARCH 2022; 174:105558. [PMID: 34998128 DOI: 10.1016/j.marenvres.2022.105558] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/09/2021] [Revised: 12/21/2021] [Accepted: 01/01/2022] [Indexed: 06/14/2023]
Abstract
The Live Fluorescently Labelled Algae (LFLA) technique has been used numerous times to estimate microzooplankton herbivory. Yet, it is unknown how mixoplankton (i.e., single-cell organisms that can combine phototrophy and phagotrophy) affect the outcome of this technique. Hence, we conducted a broad-spectrum assessment of the strengths and weaknesses of the LFLA technique, using several mixoplanktonic and protozooplanktonic grazers. Species from different taxonomic groups and different feeding mechanisms were tested in short-term experiments (ca. 5 h) in the laboratory, at different prey concentrations and during light and dark periods of the day. Overall, our findings suggest that the LFLA technique, due to its short-term nature, is an effective tracker of diel ingestion and digestion rates, and can detect new mixoplanktonic predators. We recommend that, irrespective of the prey concentration, incubations to measure grazing rates with this technique should generally be concluded within 1 h (adaptable to the environmental temperature). Nevertheless, our results also call for caution whenever using LFLA in the field: feeding mechanisms other than direct engulfment (like peduncle feeding) may provide severely biased ingestion rates. Furthermore, size and species selectivity are very hard to circumvent. To reduce the effects of selectivity, we propose the combined use of two distinctly coloured fluorochromes (i.e., distinct emission spectra). With this modification, one could either label different size ranges of prey or account for species-specific interactions in the food web.
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Affiliation(s)
- Guilherme Duarte Ferreira
- Institut de Ciències del Mar, CSIC, Pg. Marítim de la Barceloneta, 37-49, 08003, Barcelona, Spain; Marine Biological Section, University of Copenhagen, DK-3000, Helsingør, Denmark
| | - Joana Figueira
- MARE - Marine and Environmental Science Centre, Polytechnic of Leiria, Peniche, Portugal
| | - Sónia Cotrim Marques
- MARE - Marine and Environmental Science Centre, Polytechnic of Leiria, Peniche, Portugal
| | - Per Juel Hansen
- Marine Biological Section, University of Copenhagen, DK-3000, Helsingør, Denmark
| | - Albert Calbet
- Institut de Ciències del Mar, CSIC, Pg. Marítim de la Barceloneta, 37-49, 08003, Barcelona, Spain.
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Díaz PA, Fernández-Pena C, Pérez-Santos I, Baldrich Á, Díaz M, Rodríguez F. Dinophysis Ehrenberg (Dinophyceae) in Southern Chile harbours red cryptophyte plastids from Rhodomonas/Storeatula clade. HARMFUL ALGAE 2020; 99:101907. [PMID: 33218433 DOI: 10.1016/j.hal.2020.101907] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/21/2020] [Revised: 08/26/2020] [Accepted: 09/24/2020] [Indexed: 06/11/2023]
Abstract
Photosynthetic species of the dinoflagellate genus Dinophysis are known to retain temporary cryptophyte plastids of the Teleaulax/Plagioselmis/Geminigera clade after feeding the ciliate Mesodinium rubrum. In the present study, partial plastid 23S rDNA sequences were retrieved in Southern Chilean waters from oceanic (Los Lagos region), and fjord systems (Aysén region), in single cells of Dinophysis and accompanying organisms (the heliozoan Actinophrys cf. sol and tintinnid ciliates), identified by means of morphological discrimination under the light microscope. All plastid 23S rDNA sequences (n = 23) from Dinophysis spp. (Dinophysis acuta, D. caudata, D. tripos and D. subcircularis) belonged to cryptophytes from clade V (Rhinomonas, Rhodomonas and Storeatula), although they could not be identified at genus level. Moreover, five plastid sequences obtained from heliozoans (Actinophryida, tentatively identified as Actinophrys cf. sol), and tintinnid ciliates, grouped together with those cryptophyte sequences. In contrast, two additional sequences from tintinnids belonged to other taxa (chlorophytes and cyanobacteria). Overall, the present study represents the first time that red cryptophyte plastids outside of the Teleaulax/Plagioselmis/Geminigera clade dominate in wild photosynthetic Dinophysis spp. These findings suggest that either Dinophysis spp. are able to feed on other ciliate prey than Mesodinium and/or that cryptophyte plastids from clade V prevail in members of the M. rubrum species complex in the studied area.
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Affiliation(s)
- Patricio A Díaz
- Centro i~mar, Universidad de Los Lagos, Casilla 557, Puerto Montt, Chile; CeBiB, Universidad de Los Lagos, Casilla 557, Puerto Montt, Chile.
| | - Concepción Fernández-Pena
- Centro Oceanográfico de A Coruña, (IEO), Paseo Marítimo Alcalde Francisco Vázquez, 10, Coruña 15001, Spain
| | - Iván Pérez-Santos
- Centro i~mar, Universidad de Los Lagos, Casilla 557, Puerto Montt, Chile; Centro de Investigación Oceanográfica COPAS Sur-Austral, Campus Concepción, Universidad de Concepción, Concepción 4030000, Chile
| | - Ángela Baldrich
- Centro i~mar, Universidad de Los Lagos, Casilla 557, Puerto Montt, Chile; Programa de Doctorado en Ciencias, mención Manejo y Conservación de Recursos Naturales, Universidad de Los Lagos, Puerto Montt, Chile
| | - Manuel Díaz
- Programa de Investigación Pesquera & Instituto de Acuicultura, Universidad Austral de Chile, Sede Puerto Montt, Chile
| | - Francisco Rodríguez
- Centro Oceanográfico de Vigo, Instituto Español de Oceanografía (IEO), Subida a Radio Faro 50, Vigo 36390, Spain
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Fiorendino JM, Smith JL, Campbell L. Growth response of Dinophysis, Mesodinium, and Teleaulax cultures to temperature, irradiance, and salinity. HARMFUL ALGAE 2020; 98:101896. [PMID: 33129454 DOI: 10.1016/j.hal.2020.101896] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/09/2020] [Revised: 08/21/2020] [Accepted: 08/21/2020] [Indexed: 06/11/2023]
Abstract
Mixotrophic Dinophysis species threaten human health and coastal economies through the production of toxins which cause diarrhetic shellfish poisoning (DSP) in humans. Novel blooms of Dinophysis acuminata and Dinophysis ovum have occurred in North American waters in recent decades, resulting in the closure of shellfish harvesting. Understanding the ecology of Dinophysis species and their prey is essential to predicting and mitigating the impact of blooms of these dinoflagellates. The growth response of two new isolates of Dinophysis species, one isolate of Mesodinium rubrum, and two strains of Teleaulax amphioxeia were evaluated at a range of temperature, salinity, and irradiance treatments to identify possible environmental drivers of Dinophysis blooms in the Gulf of Mexico. Results showed optimal growth of T. amphioxeia and M. rubrum at 24 °C, salinity 30 - 34, and irradiances between 300 and 400 µmol quanta m - 2s - 1. Optimal Dinophysis growth was observed at salinity 22 and temperatures between 18 and 24 °C. Mesodinium and both Dinophysis responded differently to experimental treatments, which may be due to the suitability of prey and different handling of kleptochloroplasts. Dinophysis bloom onset may be initiated by warming surface waters between winter and spring in the Gulf of Mexico. Toxin profiles for these two North American isolates were distinct; Dinophysis acuminata produced okadaic acid, dinophysistoxin-1, and pectenotoxin-2 while D. ovum produced only okadaic acid. Toxin per cell for D. ovum was two orders of magnitude greater than D. acuminata. Phylogenies based on the cox1 and cob genes did not distinguish these two Dinophysis species within the D. acuminata complex.
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Affiliation(s)
- James M Fiorendino
- Department of Oceanography, Texas A&M University, College Station, TX 77843, USA
| | - Juliette L Smith
- Virginia Institute of Marine Science, College of William & Mary, Gloucester Point, Virginia, 23062, USA
| | - Lisa Campbell
- Department of Oceanography, Texas A&M University, College Station, TX 77843, USA.
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García-Portela M, Reguera B, Gago J, Le Gac M, Rodríguez F. Uptake of Inorganic and Organic Nitrogen Sources by Dinophysis acuminata and D. acuta. Microorganisms 2020; 8:microorganisms8020187. [PMID: 32013096 PMCID: PMC7074736 DOI: 10.3390/microorganisms8020187] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2019] [Revised: 01/20/2020] [Accepted: 01/25/2020] [Indexed: 01/31/2023] Open
Abstract
Dinoflagellate species of Dinophysis are obligate mixotrophs that require light, nutrients, and prey for sustained growth. Information about their nitrogenous nutrient preferences and their uptake kinetics are scarce. This study aimed to determine the preferred nitrogen sources in cultures of D. acuminata and D. acuta strains from the Galician Rías Baixas (NW Spain) and to compare their uptake kinetics. Well-fed versus starved cultures of D. acuminata and D. acuta were supplied with N15 labeled inorganic (nitrate, ammonium) and organic (urea) nutrients. Both species showed a preference for ammonium and urea whereas uptake of nitrate was negligible. Uptake rates by well-fed cells of D. acuminata and D. acuta were 200% and 50% higher, respectively, than by starved cells. Uptake of urea by D. acuminata was significantly higher than that of ammonium in both nutritional conditions. In contrast, similar uptake rates of both compounds were observed in D. acuta. The apparent inability of Dinophysis to take up nitrate suggests the existence of incomplete nitrate-reducing and assimilatory pathways, in line with the paucity of nitrate transporter homologs in the D. acuminata reference transcriptome. Results derived from this study will contribute to understand Harmful Algal Blooms succession and differences in the spatio-temporal distribution of the two Dinophysis species when they co-occur in stratified scenarios.
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Affiliation(s)
- María García-Portela
- Spanish Institute of Oceanography (IEO), Oceanographic Center of Vigo, Subida a Radio Faro 50, Cabo Estay, Canido, 36390 Vigo, Spain; (B.R.); (J.G.); (F.R.)
- Correspondence: ; Tel.: +34-637381507
| | - Beatriz Reguera
- Spanish Institute of Oceanography (IEO), Oceanographic Center of Vigo, Subida a Radio Faro 50, Cabo Estay, Canido, 36390 Vigo, Spain; (B.R.); (J.G.); (F.R.)
| | - Jesús Gago
- Spanish Institute of Oceanography (IEO), Oceanographic Center of Vigo, Subida a Radio Faro 50, Cabo Estay, Canido, 36390 Vigo, Spain; (B.R.); (J.G.); (F.R.)
| | | | - Francisco Rodríguez
- Spanish Institute of Oceanography (IEO), Oceanographic Center of Vigo, Subida a Radio Faro 50, Cabo Estay, Canido, 36390 Vigo, Spain; (B.R.); (J.G.); (F.R.)
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Park JH, Kim M, Jeong HJ, Park MG. Revisiting the taxonomy of the "Dinophysis acuminata complex'' (Dinophyta)'. HARMFUL ALGAE 2019; 88:101657. [PMID: 31582152 DOI: 10.1016/j.hal.2019.101657] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/01/2019] [Revised: 08/05/2019] [Accepted: 08/05/2019] [Indexed: 06/10/2023]
Abstract
Marine dinoflagellates of the genus Dinophysis are well known for producing diarrhetic shellfish poisoning (DSP) toxins and/or pectenotoxins which have a significant impact on public health as well as on marine aquaculture. Out of more than 80 Dinophysis species recorded so far, D. cf. acuminata is the most commonly observed in coastal areas worldwide. Due to their highly similar morphological features, however, an accurate discrimination of the various D. cf. acuminata species such as D. acuminata, D. ovum, and D. sacculus under light microscopy has proven to be a difficult task to accomplish. Hence, these species have thus far been referred to as the "Dinophysis acuminata complex". Recent studies showed a discrimination between local strains of D. acuminata and D. ovum from Galician, northwestern Spain, using the mitochondrial cox1 gene as a genetic marker in addition to commonly used morphological features such as size and contour of the large hypothecal plates, shape of the small cells formed as part of their polymorphic life-cycle, development of the left sulcal list and ribs, and length of the right sulcal list. In the present study, attempts were made to discriminate between D. acuminata and D. ovum following single-cell isolation of 54 "D. acuminata complex" collected from Korean coastal waters, based on the abovementioned traits. Morphological data showed that all the traits analyzed overlapped between the two species. The mitochondrial cox1 (cytochrome c oxidase subunit I) gene sequences of every isolate were also determined, but a genetic distinction between D. acuminata and D. ovum could not be confirmed, suggesting that the cox1 gene is not a suitable genetic marker for discrimination between the two species. The results of this study suggest that the morphological variations observed within the "D. acuminata complex" may have been caused by several factors (e.g. different geographical locations, seasonal changes, and different environmental conditions), and that D. acuminata and D. ovum may be the same species.
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Affiliation(s)
- Jeong Ha Park
- LOHABE, Department of Oceanography, Chonnam National University, Gwangju 61186, Republic of Korea
| | - Miran Kim
- Research Institute for Basic Sciences, Chonnam National University, Gwangju 61186, Republic of Korea.
| | - Hae Jin Jeong
- School of Earth and Environmental Sciences, College of Natural Sciences, Seoul National University, Seoul 08826, Republic of Korea
| | - Myung Gil Park
- LOHABE, Department of Oceanography, Chonnam National University, Gwangju 61186, Republic of Korea
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García-Portela M, Riobó P, Reguera B, Garrido JL, Blanco J, Rodríguez F. 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 2018; 54:899-917. [PMID: 30298602 DOI: 10.1111/jpy.12794] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/28/2018] [Accepted: 09/24/2018] [Indexed: 06/08/2023]
Abstract
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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Affiliation(s)
- María García-Portela
- Spanish Institute of Oceanography (IEO), Oceanographic Centre of Vigo, 36390 Vigo, Pontevedra, Spain
| | - Pilar Riobó
- Marine Research Institute (IIM-CSIC), 36208 Vigo, Pontevedra, Spain
| | - Beatriz Reguera
- Spanish Institute of Oceanography (IEO), Oceanographic Centre of Vigo, 36390 Vigo, Pontevedra, Spain
| | | | - Juan Blanco
- Marine Research Centre (CIMA), 36620 Vilanova de Arousa, Pontevedra, Spain
| | - Francisco Rodríguez
- Spanish Institute of Oceanography (IEO), Oceanographic Centre of Vigo, 36390 Vigo, Pontevedra, Spain
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