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Drouet K, Jauzein C, Gasparini S, Pavaux AS, Berdalet E, Marro S, Davenet-Sbirrazuoli V, Siano R, Lemée R. The benthic toxic dinoflagellate Ostreopsis cf. ovata in the NW Mediterranean Sea: Relationship between sea surface temperature and bloom phenology. Harmful Algae 2022; 112:102184. [PMID: 35144819 DOI: 10.1016/j.hal.2022.102184] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/30/2021] [Revised: 12/24/2021] [Accepted: 01/11/2022] [Indexed: 06/14/2023]
Abstract
Blooms of the toxic benthic dinoflagellate Ostreopsis cf. ovata can induce ecological and human health issues in certain temperate areas. In order to prevent these negative effects, long-term monitoring studies of O. cf. ovata blooms have been conducted in several impacted areas to have a comprehensive understanding of bloom dynamics and efficient tools for risk management. O. cf. ovata blooms were monitored every summer (from mid-June to the end of August) on five identified sites in Larvotto beach (Monaco, NW Mediterranean Sea), between 2007 and 2019. This time-series represents one of the largest time-series in the world describing blooms of this species. Bloom phenological features (timing, duration, maximum cell abundance and growth rate), were found to be highly variable throughout the studied period, and were analyzed as a function of different hydroclimatic parameters, including sea surface temperature (SST). The highest net growth rates were related to temperatures ranging between 21°C and 25°C, and did not coincide with maximal temperature records (27.5°C). Such results suggest that, although global warming possibly influences the expansion of O. cf. ovata from tropical to temperate waters, the definite impact of temperature on bloom dynamics might be more complex than a simple facilitation factor for algal growth, at least in NW Mediterranean waters. Furthermore, monthly SST anomalies calculated over this 13-year survey showed a strong positive correlation between spring SST positive anomalies and the bloom starting date, indicating that blooms occurred earlier in the season when spring SSTs were warmer than usual. Overall results provide tools to modelers and managers who are facing crucial challenges to predict the distribution and phenology of O. cf. ovata blooms in European coastal waters, moreover in a context of global warming.
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Affiliation(s)
- K Drouet
- Sorbonne Université, CNRS, Laboratoire d'Océanographie de Villefranche (UMR 7093), Villefranche-sur-Mer, FRANCE; Ifremer, DYNECO Pelagos, F-29280 Plouzané, FRANCE.
| | - C Jauzein
- Ifremer, DYNECO Pelagos, F-29280 Plouzané, FRANCE
| | - S Gasparini
- Sorbonne Université, CNRS, Laboratoire d'Océanographie de Villefranche (UMR 7093), Villefranche-sur-Mer, FRANCE
| | - A-S Pavaux
- Sorbonne Université, CNRS, Laboratoire d'Océanographie de Villefranche (UMR 7093), Villefranche-sur-Mer, FRANCE
| | - E Berdalet
- Institut de Ciènces del Mar (CSIC), Barcelona, SPAIN
| | - S Marro
- Sorbonne Université, CNRS, Laboratoire d'Océanographie de Villefranche (UMR 7093), Villefranche-sur-Mer, FRANCE
| | | | - R Siano
- Ifremer, DYNECO Pelagos, F-29280 Plouzané, FRANCE
| | - R Lemée
- Sorbonne Université, CNRS, Laboratoire d'Océanographie de Villefranche (UMR 7093), Villefranche-sur-Mer, FRANCE
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Pavaux AS, Velasquez-Carjaval D, Drouet K, Lebrun A, Hiroux A, Marro S, Christians E, Castagnetti S, Lemée R. Daily variations of Ostreopsis cf. ovata abundances in NW Mediterranean Sea. Harmful Algae 2021; 110:102144. [PMID: 34887015 DOI: 10.1016/j.hal.2021.102144] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/21/2021] [Revised: 11/15/2021] [Accepted: 11/16/2021] [Indexed: 06/13/2023]
Abstract
Ostreopsis cf. ovata is a benthic dinoflagellate very common in tropical and temperate coastal areas, particularly in the Mediterranean Sea. This species is also found in the plankton, i.e. swimming in the water column or in aggregates floating at the sea surface. The potential links between the planktonic and benthic populations influencing their relative distribution in the water column and attached to the benthic substrate are poorly understood. To shed light on this question, a high-frequency temporal monitoring was conducted in the Villefranche bay (France) to determine the abundance of (1) epibenthic cells attached to macroalgae, (2) planktonic cells in the water column and (3) cells in aggregates floating at the sea water surface (hereafter, referred to sea surface cells) . This monitoring was realized over 3 consecutive years (2018, 2019 and 2020) and at different phases of the bloom (exponential phase - 2020, peak - 2019 and decline phase - 2018). Strong variations in benthic and planktonic O. cf. ovata abundances were observed over the 24 h sampling cycles conducted in three consecutive years. The three populations, planktonic, benthic and sea surface cells, exhibited the highest numbers during the day (light) hours and lowest values at night in 2018 and 2019. In 2020, however, benthic abundances did not differ significantly between light and dark periods. Moreover, epibenthic cells abundances peaked in the morning, followed by the peak of the cells in the plankton and in the surface aggregates during the afternoon. Monitoring of O. cf. ovata is often based on a single sampling per day without precise indications of sampling time and shows great variability in O. cf. ovata abundances. Our observations of daily variations in cell abundances along the water column clearly indicate that time and water column depth of sampling constitute a great source of variability and have to be considered when designing new monitoring strategies to reduce variability and to harmonize data acquisition and international comparisons.
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Affiliation(s)
- Anne-Sophie Pavaux
- Sorbonne Université, CNRS, Laboratoire d'Océanographie de Villefranche, LOV, Villefranche-sur-Mer F-06230, France.
| | - David Velasquez-Carjaval
- Sorbonne Université, CNRS, Laboratoire de Biologie du Développement de Villefranche-sur-Mer (LBDV), Sorbonne Université, Villefranche-sur-Mer 06230, France; Grupo de investigación Conocimiento, Filosofía, Ciencia, Historia y Sociedad, Instituto de Filosofía, Universidad de Antioquia (UdeA). Medellín, Colombia
| | - Kévin Drouet
- Sorbonne Université, CNRS, Laboratoire d'Océanographie de Villefranche, LOV, Villefranche-sur-Mer F-06230, France
| | - Anaïs Lebrun
- Sorbonne Université, CNRS, Laboratoire d'Océanographie de Villefranche, LOV, Villefranche-sur-Mer F-06230, France
| | - Alan Hiroux
- Sorbonne Université, CNRS, Laboratoire d'Océanographie de Villefranche, LOV, Villefranche-sur-Mer F-06230, France
| | - Sophie Marro
- Sorbonne Université, CNRS, Laboratoire d'Océanographie de Villefranche, LOV, Villefranche-sur-Mer F-06230, France
| | - Elisabeth Christians
- Sorbonne Université, CNRS, Institut de la Mer de Villefranche, Villefranche-sur-Mer 06230, France
| | - Stefania Castagnetti
- Sorbonne Université, CNRS, Laboratoire de Biologie du Développement de Villefranche-sur-Mer (LBDV), Sorbonne Université, Villefranche-sur-Mer 06230, France
| | - Rodolphe Lemée
- Sorbonne Université, CNRS, Laboratoire d'Océanographie de Villefranche, LOV, Villefranche-sur-Mer F-06230, France
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Decelle J, Veronesi G, LeKieffre C, Gallet B, Chevalier F, Stryhanyuk H, Marro S, Ravanel S, Tucoulou R, Schieber N, Finazzi G, Schwab Y, Musat N. Subcellular architecture and metabolic connection in the planktonic photosymbiosis between Collodaria (radiolarians) and their microalgae. Environ Microbiol 2021; 23:6569-6586. [PMID: 34499794 DOI: 10.1111/1462-2920.15766] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2021] [Revised: 08/27/2021] [Accepted: 09/05/2021] [Indexed: 11/28/2022]
Abstract
Photosymbiosis is widespread and ecologically important in the oceanic plankton but remains poorly studied. Here, we used multimodal subcellular imaging to investigate the photosymbiosis between colonial Collodaria and their microalga dinoflagellate (Brandtodinium). We showed that this symbiosis is very dynamic whereby symbionts interact with different host cells via extracellular vesicles within the colony. 3D electron microscopy revealed that the photosynthetic apparatus of the microalgae was more voluminous in symbiosis compared to free-living while the mitochondria volume was similar. Stable isotope probing coupled with NanoSIMS showed that carbon and nitrogen were stored in the symbiotic microalga in starch granules and purine crystals respectively. Nitrogen was also allocated to the algal nucleolus. In the host, low 13 C transfer was detected in the Golgi. Metal mapping revealed that intracellular iron concentration was similar in free-living and symbiotic microalgae (c. 40 ppm) and twofold higher in the host, whereas copper concentration increased in symbionts and was detected in the host cell and extracellular vesicles. Sulfur concentration was around two times higher in symbionts (chromatin and pyrenoid) than their host. This study improves our understanding on the functioning of this oceanic photosymbiosis and paves the way for more studies to further assess its biogeochemical significance.
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Affiliation(s)
- Johan Decelle
- Univ. Grenoble Alpes, CNRS, CEA, INRAe, IRIG-LPCV, Grenoble, France.,Department of Isotope Biogeochemistry, Helmholtz Centre for Environmental Research - UFZ, Leipzig, Germany
| | - Giulia Veronesi
- CNRS, Laboratoire de Chimie et Biologie des Métaux (LCBM), UMR 5249 CNRS-CEA-UGA, F-38054, Grenoble, France.,CEA, LCBM, F-38054, Grenoble, France.,Université Grenoble Alpes, LCBM, F-38054, Grenoble, France.,ESRF, The European Synchrotron, 71, Avenue des Martyrs, 38043, Grenoble, France
| | | | - Benoit Gallet
- Institut de Biologie Structurale (IBS), University Grenoble Alpes, CEA, CNRS, 38044, Grenoble, France
| | - Fabien Chevalier
- Univ. Grenoble Alpes, CNRS, CEA, INRAe, IRIG-LPCV, Grenoble, France
| | - Hryhoriy Stryhanyuk
- Department of Isotope Biogeochemistry, Helmholtz Centre for Environmental Research - UFZ, Leipzig, Germany
| | - Sophie Marro
- Sorbonne Universités, UPMC Université Paris 06, CNRS, Laboratoire d'Océanographie de Villefranche (LOV), UMR 7093, Observatoire Océanologique, 06230, Villefranche-sur-Mer, France
| | - Stéphane Ravanel
- Univ. Grenoble Alpes, CNRS, CEA, INRAe, IRIG-LPCV, Grenoble, France
| | - Rémi Tucoulou
- ESRF, The European Synchrotron, 71, Avenue des Martyrs, 38043, Grenoble, France
| | - Nicole Schieber
- Cell Biology and Biophysics Unit, European Molecular Biology Laboratory (EMBL), 69117, Heidelberg, Germany
| | - Giovanni Finazzi
- Univ. Grenoble Alpes, CNRS, CEA, INRAe, IRIG-LPCV, Grenoble, France
| | - Yannick Schwab
- Cell Biology and Biophysics Unit, European Molecular Biology Laboratory (EMBL), 69117, Heidelberg, Germany
| | - Niculina Musat
- Department of Isotope Biogeochemistry, Helmholtz Centre for Environmental Research - UFZ, Leipzig, Germany
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Pavaux AS, Ternon E, Dufour L, Marro S, Gémin MP, Thomas OP, Lemée R. Efficient, fast and inexpensive bioassay to monitor benthic microalgae toxicity: Application to Ostreopsis species. Aquat Toxicol 2020; 223:105485. [PMID: 32353662 DOI: 10.1016/j.aquatox.2020.105485] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/18/2019] [Revised: 04/02/2020] [Accepted: 04/07/2020] [Indexed: 06/11/2023]
Abstract
Even though HPLC-MS is commonly used to quantify the toxin content of Ostreopsis spp. cells, there is a need to develop easy-to-use toxicological tests to set thresholds during Ostreopsis spp. blooms. The crustacean Artemia has been widely used to evaluate the presence and toxicity of chemicals and biological contaminants and we anticipated that it could also be useful to test Ostreopsis spp. toxicity. Its relevance was first assessed by investigating the variability of the toxic effects among Ostreopsis spp. strains and throughout the dinoflagellate life cycle in combination with chemical analyses of the toxinic content by UHPLC-HRMS. After testing the toxicity of fractions prepared from Ostreopsis spp. cells, the known ova- and paly-toxins were not the only toxic metabolites to Artemia franciscana, indicating that other toxic compounds synthesized by Ostreopsis spp. still remain to be identified. To extend the bioassay to in situ monitoring, the toxicity of the benthic microalgal consortium was tested during a natural bloom of Ostreopsis cf. ovata in the NW Mediterranean Sea. The results highlight the accuracy and sensitivity of the ecotoxicological assay with Artemia franciscana to assess the toxicity of Ostreopsis spp. blooms.
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Affiliation(s)
- Anne-Sophie Pavaux
- Sorbonne Université, CNRS, Laboratoire d'Océanographie de Villefranche, LOV, F-06230, Villefranche-sur-Mer, France.
| | - Eva Ternon
- Université Côte d'Azur, CNRS, OCA, IRD, Géoazur, 250 rue Albert Einstein, 06560, Valbonne, France
| | - Louison Dufour
- Sorbonne Université, CNRS, Laboratoire d'Océanographie de Villefranche, LOV, F-06230, Villefranche-sur-Mer, France
| | - Sophie Marro
- Sorbonne Université, CNRS, Laboratoire d'Océanographie de Villefranche, LOV, F-06230, Villefranche-sur-Mer, France
| | - Marin-Pierre Gémin
- IFREMER - Laboratoire Phycotoxines (PHYC), Rue de l'Île d'Yeu, BP 21105, F- 44311, Nantes, France
| | - Olivier P Thomas
- Marine Biodiscovery, School of Chemistry and Ryan Institute, National University of Ireland Galway, University Road, H91 TK33, Galway, Ireland
| | - Rodolphe Lemée
- Sorbonne Université, CNRS, Laboratoire d'Océanographie de Villefranche, LOV, F-06230, Villefranche-sur-Mer, France
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Decelle J, Stryhanyuk H, Gallet B, Veronesi G, Schmidt M, Balzano S, Marro S, Uwizeye C, Jouneau PH, Lupette J, Jouhet J, Maréchal E, Schwab Y, Schieber NL, Tucoulou R, Richnow H, Finazzi G, Musat N. Algal Remodeling in a Ubiquitous Planktonic Photosymbiosis. Curr Biol 2019; 29:968-978.e4. [PMID: 30827917 DOI: 10.1016/j.cub.2019.01.073] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2018] [Revised: 12/03/2018] [Accepted: 01/28/2019] [Indexed: 01/12/2023]
Abstract
Photosymbiosis between single-celled hosts and microalgae is common in oceanic plankton, especially in oligotrophic surface waters. However, the functioning of this ecologically important cell-cell interaction and the subcellular mechanisms allowing the host to accommodate and benefit from its microalgae remain enigmatic. Here, using a combination of quantitative single-cell structural and chemical imaging techniques (FIB-SEM, nanoSIMS, Synchrotron X-ray fluorescence), we show that the structural organization, physiology, and trophic status of the algal symbionts (the haptophyte Phaeocystis) significantly change within their acantharian hosts compared to their free-living phase in culture. In symbiosis, algal cell division is blocked, photosynthesis is enhanced, and cell volume is increased by up to 10-fold with a higher number of plastids (from 2 to up to 30) and thylakoid membranes. The multiplication of plastids can lead to a 38-fold increase of the total plastid volume in a cell. Subcellular mapping of nutrients (nitrogen and phosphorous) and their stoichiometric ratios shows that symbiotic algae are impoverished in phosphorous and suggests a higher investment in energy-acquisition machinery rather than in growth. Nanoscale imaging also showed that the host supplies a substantial amount of trace metals (e.g., iron and cobalt), which are stored in algal vacuoles at high concentrations (up to 660 ppm). Sulfur mapping reveals a high concentration in algal vacuoles that may be a source of antioxidant molecules. Overall, this study unveils an unprecedented morphological and metabolic transformation of microalgae following their integration into a host, and it suggests that this widespread symbiosis is a farming strategy wherein the host engulfs and exploits microalgae.
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Affiliation(s)
- Johan Decelle
- Helmholtz Centre for Environmental Research - UFZ, Department of Isotope Biogeochemistry, 04318 Leipzig, Germany.
| | - Hryhoriy Stryhanyuk
- Helmholtz Centre for Environmental Research - UFZ, Department of Isotope Biogeochemistry, 04318 Leipzig, Germany
| | - Benoit Gallet
- Institut de Biologie Structurale, Université Grenoble Alpes, CNRS, CEA, 71 Avenue des Martyrs, 38044 Grenoble, France
| | - Giulia Veronesi
- Laboratoire de Chimie et Biologie des Métaux UMR 5249, Université Grenoble Alpes, CNRS, CEA, 17 Avenue des Martyrs, 38054 Grenoble, France; ESRF, The European Synchrotron Radiation Facility, 71 Avenue des Martyrs, 38043 Grenoble, France
| | - Matthias Schmidt
- Helmholtz Centre for Environmental Research - UFZ, Department of Isotope Biogeochemistry, 04318 Leipzig, Germany
| | - Sergio Balzano
- NIOZ, Royal Netherlands Institute for Sea Research, Department of Marine Microbiology and Biogeochemistry, and Utrecht University, PO Box 59, 1790 AB Den Burg, the Netherlands
| | - Sophie Marro
- Sorbonne Universités, UPMC Université Paris 06, CNRS, Laboratoire d'Océanographie de Villefranche UMR7093, Observatoire Océanologique, 06230 Villefranche-sur-Mer, France
| | - Clarisse Uwizeye
- Cell & Plant Physiology Laboratory, University of Grenoble Alpes, CNRS, CEA, INRA, 38054 Grenoble Cedex 9, France
| | - Pierre-Henri Jouneau
- Institut Nanosciences et Cryogénie, Université Grenoble Alpes, CEA, 38054 Grenoble, France
| | - Josselin Lupette
- Cell & Plant Physiology Laboratory, University of Grenoble Alpes, CNRS, CEA, INRA, 38054 Grenoble Cedex 9, France
| | - Juliette Jouhet
- Cell & Plant Physiology Laboratory, University of Grenoble Alpes, CNRS, CEA, INRA, 38054 Grenoble Cedex 9, France
| | - Eric Maréchal
- Cell & Plant Physiology Laboratory, University of Grenoble Alpes, CNRS, CEA, INRA, 38054 Grenoble Cedex 9, France
| | - Yannick Schwab
- Cell Biology and Biophysics Unit, European Molecular Biology Laboratory, 69117 Heidelberg, Germany
| | - Nicole L Schieber
- Cell Biology and Biophysics Unit, European Molecular Biology Laboratory, 69117 Heidelberg, Germany
| | - Rémi Tucoulou
- ESRF, The European Synchrotron Radiation Facility, 71 Avenue des Martyrs, 38043 Grenoble, France
| | - Hans Richnow
- Helmholtz Centre for Environmental Research - UFZ, Department of Isotope Biogeochemistry, 04318 Leipzig, Germany
| | - Giovanni Finazzi
- Cell & Plant Physiology Laboratory, University of Grenoble Alpes, CNRS, CEA, INRA, 38054 Grenoble Cedex 9, France
| | - Niculina Musat
- Helmholtz Centre for Environmental Research - UFZ, Department of Isotope Biogeochemistry, 04318 Leipzig, Germany
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Ternon E, Pavaux AS, Marro S, Thomas OP, Lemée R. Allelopathic interactions between the benthic toxic dinoflagellate Ostreopsis cf. ovata and a co-occurring diatom. Harmful Algae 2018; 75:35-44. [PMID: 29778224 DOI: 10.1016/j.hal.2018.04.003] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/30/2017] [Revised: 03/28/2018] [Accepted: 04/05/2018] [Indexed: 06/08/2023]
Abstract
For decades the microphytobenthos assemblage in the coastal Mediterranean Sea has been regularly colonized by the toxic benthic dinoflagellate Ostreopsis cf. ovata. This harmful algal species is a toxin producer and occupies the same ecological niche as various diatoms. Surprisingly, there are only few insights reported on the physiological responses of diatoms to blooms of O. cf. ovata The chemical interactions of O. cf. ovata with the co-occurring diatom Licmophora paradoxa was studied using a bioassay (measuring impact of cell-free culture filtrate) and a co-culture approach (separate by a membrane) to investigate the effects of the exometabolome and its mode of action. Bioassays highlighted a toxic effect of the exometabolome of O. cf. ovata on the diatom photosynthetic activity. However, the co-cultures revealed that these toxic effects do not occur through remote allelopathy. Contact or close interactions between cells of the two species is most likely needed to impair the diatom growth. Ovatoxins are suspected to be the toxic metabolites secreted by O. cf. ovata although the current set of data did not give confirmation of this assumption. Interestingly, the exometabolome of L. paradoxa impaired the growth and the photochemistry of O. cf. ovata in both bioassays and co-cultures. Some biomarkers possibly involved for the effect were identified using a metabolomic approach and may correspond to oxylipins, however a bacterial source of the bioactive metabolites is also considered.
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Affiliation(s)
- Eva Ternon
- Université Côte d'Azur, CNRS, OCA, IRD, Géoazur, 250 rue Albert Einstein, 06560 Valbonne, France.
| | - Anne-Sophie Pavaux
- Université Côte d'Azur, CNRS, OCA, IRD, Géoazur, 250 rue Albert Einstein, 06560 Valbonne, France; Sorbonne Universités, Université Pierre et Marie-Curie Paris 6, INSU-CNRS, Laboratoire d'Océanographie de Villefranche, 06234 Villefranche sur mer, France
| | - Sophie Marro
- Sorbonne Universités, Université Pierre et Marie-Curie Paris 6, INSU-CNRS, Laboratoire d'Océanographie de Villefranche, 06234 Villefranche sur mer, France
| | - Olivier P Thomas
- Université Côte d'Azur, CNRS, OCA, IRD, Géoazur, 250 rue Albert Einstein, 06560 Valbonne, France; Marine Biodiscovery, School of Chemistry and Ryan Institute, National University of Ireland Galway, University Road, H91 TK33 Galway, Ireland
| | - Rodolphe Lemée
- Sorbonne Universités, Université Pierre et Marie-Curie Paris 6, INSU-CNRS, Laboratoire d'Océanographie de Villefranche, 06234 Villefranche sur mer, France
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Pedrotti ML, Mousseau L, Marro S, Passafiume O, Gossaert M, Labat JP. Variability of ultraplankton composition and distribution in an oligotrophic coastal ecosystem of the NW Mediterranean Sea derived from a two-year survey at the single cell level. PLoS One 2017; 12:e0190121. [PMID: 29267395 PMCID: PMC5739496 DOI: 10.1371/journal.pone.0190121] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2016] [Accepted: 12/08/2017] [Indexed: 11/19/2022] Open
Abstract
Ultraplankton [heterotrophic prokaryotes and ultraphytoplankton (<10 μm)] were monitored weekly over two years (2009 & 2010) in a coastal area of the NW Mediterranean Sea. Six clusters were differentiated by flow cytometry on the basis of their optical properties, two heterotrophic prokaryote (HP) subgroups labelled LNA and HNA (low and high nucleic acid content respectively), Prochlorococcus, Synechococcus, autotrophic picoeukaryotes and nanoeukaryotes. HP represented an important component of the microbial assemblage over the survey with relatively small abundance variation through seasons. The carbon biomass ratio HP/ultraphytoplankton averaged 0.45, however this ratio exceeded 1 during spring. Ultraphytoplankton biomass made about 50% of the total autotrophic carbon estimates but this contribution increased up to 97% and 67% during the 2009 and 2010 spring periods respectively. Within ultraphytoplankton, nanoeukaryote represent the most important ultraphytoplankton group in terms of autotrophic carbon biomass (up to 70%). Picoeukaryote maximum abundance occurred in winter. Synechococcus was the most abundant population (maximum 1.2 x 10 5 cells cm-3) particularly in spring where it represented up to 54% of ultraphytoplankton carbon biomass. The warmer winter-spring temperatures and the lengthening of the stratification period created a favorable situation for the earlier appearance of Synechococcus and its persistence throughout summer, paralleling Prochlorococcus development. Prochlorococcus was dominant over summer and autumn with concentrations up to 1.0 × 10 5 cells cm-3. While the abundance of Synechococcus throughout survey was of the same order as that reported in western Mediterranean Sea, Prochlorococcus was more abundant and similar to the more typical oligotrophic and warm waters. The abundance variation of the ultraplankton components through the survey was relatable to variations in the hydrological and nutrient conditions.
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Affiliation(s)
- Maria Luiza Pedrotti
- Sorbonne Universités, UPMC Univ Paris 06, UMR 7093, LOV, Villefranche sur mer, France
- CNRS, UMR 7093, LOV, Villefranche-sur-Mer, France
| | - Laure Mousseau
- Sorbonne Universités, UPMC Univ Paris 06, UMR 7093, LOV, Villefranche sur mer, France
- CNRS, UMR 7093, LOV, Villefranche-sur-Mer, France
| | - Sophie Marro
- Sorbonne Universités, UPMC Univ Paris 06, UMR 7093, LOV, Villefranche sur mer, France
- CNRS, UMR 7093, LOV, Villefranche-sur-Mer, France
| | - Ornella Passafiume
- Sorbonne Universités, UPMC Univ Paris 06, UMR 7093, LOV, Villefranche sur mer, France
- CNRS, UMR 7093, LOV, Villefranche-sur-Mer, France
| | - Marjorie Gossaert
- Sorbonne Universités, UPMC Univ Paris 06, UMR 7093, LOV, Villefranche sur mer, France
- CNRS, UMR 7093, LOV, Villefranche-sur-Mer, France
| | - Jean-Philippe Labat
- Sorbonne Universités, UPMC Univ Paris 06, UMR 7093, LOV, Villefranche sur mer, France
- CNRS, UMR 7093, LOV, Villefranche-sur-Mer, France
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Thyssen M, Grégori GJ, Grisoni JM, Pedrotti ML, Mousseau L, Artigas LF, Marro S, Garcia N, Passafiume O, Denis MJ. Onset of the spring bloom in the northwestern Mediterranean Sea: influence of environmental pulse events on the in situ hourly-scale dynamics of the phytoplankton community structure. Front Microbiol 2014; 5:387. [PMID: 25161647 PMCID: PMC4129916 DOI: 10.3389/fmicb.2014.00387] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2014] [Accepted: 07/11/2014] [Indexed: 11/13/2022] Open
Abstract
Most of phytoplankton influence is barely understood at the sub meso scale and daily scale because of the lack of means to simultaneously assess phytoplankton functionality, dynamics and community structure. For a few years now, it has been possible to address this objective with an automated in situ high frequency sampling strategy. In order to study the influence of environmental short-term events (nutrients, wind speed, precipitation, solar radiation, temperature, and salinity) on the onset of the phytoplankton bloom in the oligotrophic Bay of Villefranche-sur-Mer (NW Mediterranean Sea), a fully remotely controlled automated flow cytometer (CytoSense) was deployed on a solar-powered platform (EOL buoy, CNRS-Mobilis). The CytoSense carried out single-cell analyses on particles (1-800 μm in width, up to several mm in length), recording optical pulse shapes when analyzing several cm(3). Samples were taken every 2 h in the surface waters during 2 months. Up to 6 phytoplankton clusters were resolved based on their optical properties (PicoFLO, Picoeukaryotes, Nanophytoplankton, Microphytoplankton, HighSWS, HighFLO). Three main abundance pulses involving the 6 phytoplankton groups monitored indicated that the spring bloom not only depends on light and water column stability, but also on short-term events such as wind events and precipitation followed by nutrient pulses. Wind and precipitation were also determinant in the collapse of the clusters' abundances. These events occurred within a couple of days, and phytoplankton abundance reacted within days. The third abundance pulse could be considered as the spring bloom commonly observed in the area. The high frequency data-set made it possible to study the phytoplankton cell cycle based on daily cycles of forward scatter and abundance. The combination of daily cell cycle, abundance trends and environmental pulses will open the way to the study of phytoplankton short-term reactivity to environmental conditions.
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Affiliation(s)
- Melilotus Thyssen
- CNRS/INSU, IRD, Mediterranean Institute of Oceanography, Aix Marseille UniversitéMarseille, France
| | - Gerald J. Grégori
- CNRS/INSU, IRD, Mediterranean Institute of Oceanography, Aix Marseille UniversitéMarseille, France
| | - Jean-Michel Grisoni
- Sorbonne Universités, UPMC Univ. Paris 06, UMR 7093, LOV, Observatoire OcéanologiqueVillefranche-sur-Mer, France
- CNRS, UMR 7093, LOV, Observatoire OcéanologiqueVillefranche-sur-Mer, France
| | - Maria Luiza Pedrotti
- Sorbonne Universités, UPMC Univ. Paris 06, UMR 7093, LOV, Observatoire OcéanologiqueVillefranche-sur-Mer, France
- CNRS, UMR 7093, LOV, Observatoire OcéanologiqueVillefranche-sur-Mer, France
| | - Laure Mousseau
- Sorbonne Universités, UPMC Univ. Paris 06, UMR 7093, LOV, Observatoire OcéanologiqueVillefranche-sur-Mer, France
- CNRS, UMR 7093, LOV, Observatoire OcéanologiqueVillefranche-sur-Mer, France
| | - Luis F. Artigas
- Laboratoire d'Océanologie et Géosciences, Univ. du Littoral Côte d'Opale, CNRS, UMR8187Wimereux, France
| | - Sophie Marro
- Sorbonne Universités, UPMC Univ. Paris 06, UMR 7093, LOV, Observatoire OcéanologiqueVillefranche-sur-Mer, France
- CNRS, UMR 7093, LOV, Observatoire OcéanologiqueVillefranche-sur-Mer, France
| | - Nicole Garcia
- CNRS/INSU, IRD, Mediterranean Institute of Oceanography, Aix Marseille UniversitéMarseille, France
| | - Ornella Passafiume
- Sorbonne Universités, UPMC Univ. Paris 06, UMR 7093, LOV, Observatoire OcéanologiqueVillefranche-sur-Mer, France
- CNRS, UMR 7093, LOV, Observatoire OcéanologiqueVillefranche-sur-Mer, France
| | - Michel J. Denis
- CNRS/INSU, IRD, Mediterranean Institute of Oceanography, Aix Marseille UniversitéMarseille, France
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Sidi-Boumedine K, Duquesne V, Fernandes I, Marro S, Thiéry R. Evaluation of randomly amplified polymorphic DNA (RAPD) for discrimination of Coxiella burnetii ruminant strains isolated in France. Clin Microbiol Infect 2009; 15 Suppl 2:194-5. [DOI: 10.1111/j.1469-0691.2008.02271.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Range R, Lapraz F, Quirin M, Marro S, Besnardeau L, Lepage T. Cis-regulatory analysis of nodal and maternal control of dorsal-ventral axis formation by Univin, a TGF-β related to Vg1. Development 2007; 134:3649-64. [PMID: 17855430 DOI: 10.1242/dev.007799] [Citation(s) in RCA: 97] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The TGF-β family member Nodal is essential for specification of the dorsal-ventral axis of the sea urchin embryo, but the molecular factors regulating its expression are not known. Analysis of the nodalpromoter is an excellent entry point to identify these factors and to dissect the regulatory logic driving dorsal-ventral axis specification. Using phylogenetic footprinting, we delineated two regulatory regions located in the 5′ region of the nodal promoter and in the intron that are required for correct spatial expression and for autoregulation. The 5′regulatory region contains essential binding sites for homeodomain, bZIP, Oct,Tcf/Lef, Sox and Smad transcription factors, and a binding site for an unidentified spatial repressor possibly related to Myb. Soon after its initiation, nodal expression critically requires autoregulation by Nodal and signaling by the maternal TGF-β Univin. We show that Univin is related to Vg1, that both Nodal and Univin signal through Alk4/5/7, and that zygotic expression of univin, like that of nodal, is dependent on SoxB1 function and Tcf/β-catenin signaling. This work shows that Tcf, SoxB1 and Univin play essential roles in the regulation of nodal expression in the sea urchin and suggests that some of the regulatory interactions controlling nodal expression predate the chordates. The data are consistent with a model of nodal regulation in which a maternal TGF-β acts in synergy with maternal transcription factors and with spatial repressors to establish the dorsal-ventral axis of the sea urchin embryo.
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Affiliation(s)
- Ryan Range
- UMR 7009 CNRS, Université Pierre et Marie Curie (Paris 6 Observatoire Océanologique, 06230 Villefranche-sur-mer, France
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