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Kahil K, Weiner S, Addadi L, Gal A. Ion Pathways in Biomineralization: Perspectives on Uptake, Transport, and Deposition of Calcium, Carbonate, and Phosphate. J Am Chem Soc 2021; 143:21100-21112. [PMID: 34881565 PMCID: PMC8704196 DOI: 10.1021/jacs.1c09174] [Citation(s) in RCA: 29] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2021] [Indexed: 12/19/2022]
Abstract
Minerals are formed by organisms in all of the kingdoms of life. Mineral formation pathways all involve uptake of ions from the environment, transport of ions by cells, sometimes temporary storage, and ultimately deposition in or outside of the cells. Even though the details of how all this is achieved vary enormously, all pathways need to respect both the chemical limitations of ion manipulation, as well as the many "housekeeping" roles of ions in cell functioning. Here we provide a chemical perspective on the biological pathways of biomineralization. Our approach is to compare and contrast the ion pathways involving calcium, phosphate, and carbonate in three very different organisms: the enormously abundant unicellular marine coccolithophores, the well investigated sea urchin larval model for single crystal formation, and the complex pathways used by vertebrates to form their bones. The comparison highlights both common and unique processes. Significantly, phosphate is involved in regulating calcium carbonate deposition and carbonate is involved in regulating calcium phosphate deposition. One often overlooked commonality is that, from uptake to deposition, the solutions involved are usually supersaturated. This therefore requires not only avoiding mineral deposition where it is not needed but also exploiting this saturated state to produce unstable mineral precursors that can be conveniently stored, redissolved, and manipulated into diverse shapes and upon deposition transformed into more ordered and hence often functional final deposits.
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Affiliation(s)
- Keren Kahil
- Department
of Chemical and Structural Biology and Department of Plant and Environmental
Sciences, Weizmann Institute of Science, 7610001 Rehovot, Israel
| | - Steve Weiner
- Department
of Chemical and Structural Biology and Department of Plant and Environmental
Sciences, Weizmann Institute of Science, 7610001 Rehovot, Israel
| | - Lia Addadi
- Department
of Chemical and Structural Biology and Department of Plant and Environmental
Sciences, Weizmann Institute of Science, 7610001 Rehovot, Israel
| | - Assaf Gal
- Department
of Chemical and Structural Biology and Department of Plant and Environmental
Sciences, Weizmann Institute of Science, 7610001 Rehovot, Israel
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Brownlee C, Langer G, Wheeler GL. Coccolithophore calcification: Changing paradigms in changing oceans. Acta Biomater 2021; 120:4-11. [PMID: 32763469 DOI: 10.1016/j.actbio.2020.07.050] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2020] [Revised: 07/13/2020] [Accepted: 07/26/2020] [Indexed: 11/30/2022]
Abstract
Coccolithophores represent a major component of the marine phytoplankton and contribute to the bulk of biogenic calcite formation on Earth. These unicellular protists produce minute calcite scales (coccoliths) within the cell, which are secreted to the cell surface. Individual coccoliths and their arrangements on the cell surface display a wide range of morphological variations. This review explores some of the recent evidence that points to similarities and differences in the mechanisms of calcification, focussing on the transport mechanisms that bring substrates to, and remove products from the site of calcification, together with new findings on factors that regulate coccolith morphology. We argue that better knowledge of these mechanisms and their variations is needed to inform more generally how different species of coccolithophore are likely to respond to changes in ocean chemistry. STATEMENT OF SIGNIFICANCE: Coccolithophores, minute single celled phytoplankton are the major producers of biogenic carbonate on Earth. They also represent an important component of the ocean's biota and contribute significantly to global carbon fluxes. Coccolithophores produce intricate calcite scales (coccoliths) internally that they secrete onto their external surface. This review presents some recent key findings on the mechanisms underlying the production of coccoliths. It also considers the factors that regulate the rate of production as well as the variety of shapes of individual coccoliths and their arrangements at the cell surface. Understanding these processes is needed to allow better predictions of how coccolithophores may respond to changing ocean chemistry associated with climate change.
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Affiliation(s)
- Colin Brownlee
- Marine Biological Association, The Laboratory, Citadel Hill, Plymouth PL1 2PB, UK; School of Ocean and Earth Sciences, University of Southampton, Southampton SO14 3ZH, UK.
| | - Gerald Langer
- Marine Biological Association, The Laboratory, Citadel Hill, Plymouth PL1 2PB, UK
| | - Glen L Wheeler
- Marine Biological Association, The Laboratory, Citadel Hill, Plymouth PL1 2PB, UK
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3
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Nam O, Suzuki I, Shiraiwa Y, Jin E. Association of Phosphatidylinositol-Specific Phospholipase C with Calcium-Induced Biomineralization in the Coccolithophore Emiliania huxleyi. Microorganisms 2020; 8:E1389. [PMID: 32927844 PMCID: PMC7563939 DOI: 10.3390/microorganisms8091389] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2020] [Revised: 09/08/2020] [Accepted: 09/09/2020] [Indexed: 11/17/2022] Open
Abstract
Biomineralization by calcifying microalgae is a precisely controlled intracellular calcification process that produces delicate calcite scales (or coccoliths) in the coccolithophore Emiliania huxleyi (Haptophycea). Despite its importance in biogeochemical cycles and the marine environment globally, the underlying molecular mechanism of intracellular coccolith formation, which requires calcium, bicarbonate, and coccolith-polysaccharides, remains unclear. In E. huxleyi CCMP 371, we demonstrated that reducing the calcium concentration from 10 (ambient seawater) to 0.1 mM strongly restricted coccolith production, which was then recovered by adding 10 mM calcium, irrespective of inorganic phosphate conditions, indicating that coccolith production could be finely controlled by the calcium supply. Using this strain, we investigated the expression of differentially expressed genes (DEGs) to observe the cellular events induced by changes in calcium concentrations. Intriguingly, DEG analysis revealed that the phosphatidylinositol-specific phospholipase C (PI-PLC) gene was upregulated and coccolith production by cells was blocked by the PI-PLC inhibitor U73122 under conditions closely associated with calcium-induced calcification. These findings imply that PI-PLC plays an important role in the biomineralization process of the coccolithophore E. huxleyi.
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Affiliation(s)
- Onyou Nam
- Department of Life Science, Research Institute for Natural Sciences, Hanyang University, Seoul 04763, Korea;
| | - Iwane Suzuki
- Faculty of Life and Environmental Sciences, University of Tsukuba, Tsukuba, Ibaraki 305-8572, Japan; (I.S.); (Y.S.)
| | - Yoshihiro Shiraiwa
- Faculty of Life and Environmental Sciences, University of Tsukuba, Tsukuba, Ibaraki 305-8572, Japan; (I.S.); (Y.S.)
| | - EonSeon Jin
- Department of Life Science, Research Institute for Natural Sciences, Hanyang University, Seoul 04763, Korea;
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Sezer N, Kılıç Ö, Sıkdokur E, Çayır A, Belivermiş M. Impacts of elevated pCO 2 on Mediterranean mussel (Mytilus galloprovincialis): Metal bioaccumulation, physiological and cellular parameters. MARINE ENVIRONMENTAL RESEARCH 2020; 160:104987. [PMID: 32907725 DOI: 10.1016/j.marenvres.2020.104987] [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: 02/04/2020] [Revised: 04/06/2020] [Accepted: 04/09/2020] [Indexed: 06/11/2023]
Abstract
Ocean acidification alters physiology, acid-base balance and metabolic activity in marine animals. Near future elevated pCO2 conditions could be expected to influence the bioaccumulation of metals, feeding rate and immune parameters in marine mussels. To better understand such impairments, a series of laboratory-controlled experiment was conducted by using a model marine mussel, Mytilus galloprovincialis. The mussels were exposed to three pH conditions according to the projected CO2 emissions in the near future (one ambient: 8.10 and two reduced: 7.80 and 7.50). At first, the bioconcentration of Ag and Cd was studied in both juvenile (2.5 cm) and adult (5.1 cm) mussels by using a highly sensitive radiotracer method (110mAg and 109Cd). The uptake and depuration kinetics were followed 21 and 30 days, respectively. The biokinetic experiments demonstrated that the effect of ocean acidification on bioconcentration was metal-specific and size-specific. The uptake, depuration and tissue distribution of 110mAg were not affected by elevated pCO2 in both juvenile and adult mussels, whereas 109Cd uptake significantly increased with decreasing pH in juveniles but not in adults. Regardless of pH, 110mAg accumulated more efficiently in juvenile mussels than adult mussels. After executing the biokinetic experiment, the perturbation was sustained by using the same mussels and the same experimental set-up, which enabled us to determine filtration rate, haemocyte viability, lysosomal membrane stability, circulating cell-free nucleic acids (ccf-NAs) and protein (ccf-protein) levels. The filtration rate and haemocyte viability gradually decreased by increasing pCO2 level, whereas the lysosomal membrane stability, ccf-NAs, and ccf-protein levels remained unchanged in the mussels exposed to elevated pCO2 for eighty-two days. This study suggests that acidified seawater partially shift metal bioaccumulation, physiological and cellular parameters in the mussel Mytilus galloprovincialis.
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Affiliation(s)
- Narin Sezer
- Department of Biology, Faculty of Science, Istanbul University, 34134, Vezneciler, Istanbul, Turkey
| | - Önder Kılıç
- Department of Biology, Faculty of Science, Istanbul University, 34134, Vezneciler, Istanbul, Turkey
| | - Ercan Sıkdokur
- Institute of Graduate Studies in Sciences, Istanbul University, Suleymaniye, Istanbul, Turkey
| | - Akın Çayır
- Vocational Health College, Çanakkale Onsekiz Mart University, Çanakkale, Turkey
| | - Murat Belivermiş
- Department of Biology, Faculty of Science, Istanbul University, 34134, Vezneciler, Istanbul, Turkey.
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5
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Giannopoulos A, Nikolopoulos D, Bresta P, Samantas A, Reppa C, Karaboiki K, Dotsika E, Fasseas C, Liakopoulos G, Karabourniotis G. Cystoliths of Parietaria judaica can serve as an internal source of CO2 for photosynthetic assimilation when stomata are closed. JOURNAL OF EXPERIMENTAL BOTANY 2019; 70:5753-5763. [PMID: 31270538 DOI: 10.1093/jxb/erz316] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/08/2019] [Accepted: 06/25/2019] [Indexed: 06/09/2023]
Abstract
The recently reported 'alarm photosynthesis' acts as a biochemical process that assimilates CO2 derived from the decomposition of calcium oxalate crystals. This study examined whether CaCO3 cystoliths could also serve as CO2 pools, fulfilling a similar role. Shoots of Parietaria judaica were subjected to carbon starvation, abscisic acid (ABA), or bicarbonate treatments, and the volume of cystoliths and the photochemical parameters of photosystem II (PSII) were determined. The size of cystoliths was reduced under carbon starvation or ABA treatments, whereas it was restored by xylem-provided bicarbonate. Under carbon starvation, ABA, or bicarbonate treatments, the photochemical efficiency of PSII was higher, while non-photochemical quenching, representing the safe dissipation of excess PSII energy due to lack of electron sinks, was lower in treated samples compared with controls. This observation suggests the involvement of ABA or other carbon starvation cues in the release of subsidiary CO2 for photosynthesis, inevitably from an internal source, which could be the cystoliths. Carbon remobilized from cystoliths can be photosynthetically assimilated, thus acting as a safety valve under stress. Together with alarm photosynthesis, these results show a tight link between leaf carbon deposits and photosynthesis.
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Affiliation(s)
- Andreas Giannopoulos
- Laboratory of Plant Physiology, Faculty of Crop Science, Agricultural University of Athens, Athens, Greece
| | - Dimosthenis Nikolopoulos
- Laboratory of Plant Physiology, Faculty of Crop Science, Agricultural University of Athens, Athens, Greece
| | - Panagiota Bresta
- Laboratory of Plant Physiology, Faculty of Crop Science, Agricultural University of Athens, Athens, Greece
| | - Aris Samantas
- Laboratory of Plant Physiology, Faculty of Crop Science, Agricultural University of Athens, Athens, Greece
| | - Chrysavgi Reppa
- Laboratory of Plant Physiology, Faculty of Crop Science, Agricultural University of Athens, Athens, Greece
| | - Kalliopi Karaboiki
- Laboratory of Plant Physiology, Faculty of Crop Science, Agricultural University of Athens, Athens, Greece
| | - Elissavet Dotsika
- Stable Isotope Unit, Institute of Material Science, National Centre for Scientific Research 'Demokritos', Athens, Greece
| | - Constantinos Fasseas
- Laboratory of Electron Microscopy, Faculty of Crop Science, Agricultural University of Athens, Athens, Greece
| | - Georgios Liakopoulos
- Laboratory of Plant Physiology, Faculty of Crop Science, Agricultural University of Athens, Athens, Greece
| | - George Karabourniotis
- Laboratory of Plant Physiology, Faculty of Crop Science, Agricultural University of Athens, Athens, Greece
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6
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Nam O, Park JM, Lee H, Jin E. De novo transcriptome profile of coccolithophorid alga Emiliania huxleyi CCMP371 at different calcium concentrations with proteome analysis. PLoS One 2019; 14:e0221938. [PMID: 31465514 PMCID: PMC6715215 DOI: 10.1371/journal.pone.0221938] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2019] [Accepted: 08/19/2019] [Indexed: 12/16/2022] Open
Abstract
The haptophyte alga Emiliania huxleyi is the most abundant coccolithophore in the modern ocean and produces elaborate calcite crystals, called coccolith, in a separate intracellular compartment known as the coccolith vesicle. Despite the importance of biomineralization in coccolithophores, the molecular mechanism underlying it remains unclear. Understanding this precise machinery at the molecular level will provide the knowledge needed to enable further manipulation of biomineralization. In our previous study, altering the calcium concentration modified the calcifying ability of E. huxleyi CCMP371. Therefore in this study, we tested E. huxleyi cells acclimated to three different calcium concentrations (0, 0.1, and 10 mM). To understand the whole transcript profile at different calcium concentrations, RNA-sequencing was performed and used for de novo assembly and annotation. The differentially expressed genes (DEGs) among the three different calcium concentrations were analyzed. The functional classification by gene ontology (GO) revealed that 'intrinsic component of membrane' was the most enriched of the GO terms at the ambient calcium concentration (10 mM) compared with the limited calcium concentrations (0 and 0.1 mM). Moreover, the DEGs in those comparisons were enriched mainly in 'secondary metabolites biosynthesis, transport and catabolism' and 'signal transduction mechanisms' in the KOG clusters and 'processing in endoplasmic reticulum', and 'ABC transporters' in the KEGG pathways. Furthermore, metabolic pathways involved in protein synthesis were enriched among the differentially expressed proteins. The results of this study provide a molecular profile for understanding the expression of transcripts and proteins in E. huxleyi at different calcium concentrations, which will help to identify the detailed mechanism of its calcification.
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Affiliation(s)
- Onyou Nam
- Department of Life Science, Hanyang University, Seoul, Republic of Korea
| | - Jong-Moon Park
- Gachon Institute of Pharmaceutical Sciences, Gachon College of Pharmacy, Gachon University, Incheon, Republic of Korea
| | - Hookeun Lee
- Gachon Institute of Pharmaceutical Sciences, Gachon College of Pharmacy, Gachon University, Incheon, Republic of Korea
| | - EonSeon Jin
- Department of Life Science, Hanyang University, Seoul, Republic of Korea
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7
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Walker CE, Taylor AR, Langer G, Durak GM, Heath S, Probert I, Tyrrell T, Brownlee C, Wheeler GL. The requirement for calcification differs between ecologically important coccolithophore species. THE NEW PHYTOLOGIST 2018; 220:147-162. [PMID: 29916209 PMCID: PMC6175242 DOI: 10.1111/nph.15272] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/15/2018] [Accepted: 05/07/2018] [Indexed: 05/24/2023]
Abstract
Coccolithophores are globally distributed unicellular marine algae that are characterized by their covering of calcite coccoliths. Calcification by coccolithophores contributes significantly to global biogeochemical cycles. However, the physiological requirement for calcification remains poorly understood as non-calcifying strains of some commonly used model species, such as Emiliania huxleyi, grow normally in laboratory culture. To determine whether the requirement for calcification differs between coccolithophore species, we utilized multiple independent methodologies to disrupt calcification in two important species of coccolithophore: E. huxleyi and Coccolithus braarudii. We investigated their physiological response and used time-lapse imaging to visualize the processes of calcification and cell division in individual cells. Disruption of calcification resulted in major growth defects in C. braarudii, but not in E. huxleyi. We found no evidence that calcification supports photosynthesis in C. braarudii, but showed that an inability to maintain an intact coccosphere results in cell cycle arrest. We found that C. braarudii is very different from E. huxleyi as it exhibits an obligate requirement for calcification. The identification of a growth defect in C. braarudii resulting from disruption of the coccosphere may be important in considering their response to future changes in ocean carbonate chemistry.
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Affiliation(s)
- Charlotte E. Walker
- Marine Biological AssociationPlymouthPL1 2PBUK
- School of Ocean and Earth ScienceUniversity of SouthamptonSouthamptonSO14 3ZHUK
| | - Alison R. Taylor
- Department of Biology and Marine BiologyUniversity of North Carolina WilmingtonWilmingtonNC28403‐591USA
| | | | | | - Sarah Heath
- Marine Biological AssociationPlymouthPL1 2PBUK
| | - Ian Probert
- Station Biologique de RoscoffPlace Georges Teisser29680RoscoffFrance
| | - Toby Tyrrell
- School of Ocean and Earth ScienceUniversity of SouthamptonSouthamptonSO14 3ZHUK
| | - Colin Brownlee
- Marine Biological AssociationPlymouthPL1 2PBUK
- School of Ocean and Earth ScienceUniversity of SouthamptonSouthamptonSO14 3ZHUK
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8
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Poschenrieder C, Fernández JA, Rubio L, Pérez L, Terés J, Barceló J. Transport and Use of Bicarbonate in Plants: Current Knowledge and Challenges Ahead. Int J Mol Sci 2018; 19:E1352. [PMID: 29751549 PMCID: PMC5983714 DOI: 10.3390/ijms19051352] [Citation(s) in RCA: 42] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2018] [Revised: 04/27/2018] [Accepted: 04/28/2018] [Indexed: 01/09/2023] Open
Abstract
Bicarbonate plays a fundamental role in the cell pH status in all organisms. In autotrophs, HCO₃− may further contribute to carbon concentration mechanisms (CCM). This is especially relevant in the CO₂-poor habitats of cyanobacteria, aquatic microalgae, and macrophytes. Photosynthesis of terrestrial plants can also benefit from CCM as evidenced by the evolution of C₄ and Crassulacean Acid Metabolism (CAM). The presence of HCO₃− in all organisms leads to more questions regarding the mechanisms of uptake and membrane transport in these different biological systems. This review aims to provide an overview of the transport and metabolic processes related to HCO₃− in microalgae, macroalgae, seagrasses, and terrestrial plants. HCO₃− transport in cyanobacteria and human cells is much better documented and is included for comparison. We further comment on the metabolic roles of HCO₃− in plants by focusing on the diversity and functions of carbonic anhydrases and PEP carboxylases as well as on the signaling role of CO₂/HCO₃− in stomatal guard cells. Plant responses to excess soil HCO₃− is briefly addressed. In conclusion, there are still considerable gaps in our knowledge of HCO₃− uptake and transport in plants that hamper the development of breeding strategies for both more efficient CCM and better HCO₃− tolerance in crop plants.
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Affiliation(s)
- Charlotte Poschenrieder
- Plant Physiology Lab., Bioscience Faculty, Universidad Autónoma de Barcelona, 08193 Barcelona, Spain.
| | - José Antonio Fernández
- Department Biologia. Vegetal, Campus Teatinos, Universidad de Málaga, 29071 Málaga, Spain.
| | - Lourdes Rubio
- Department Biologia. Vegetal, Campus Teatinos, Universidad de Málaga, 29071 Málaga, Spain.
| | - Laura Pérez
- Plant Physiology Lab., Bioscience Faculty, Universidad Autónoma de Barcelona, 08193 Barcelona, Spain.
| | - Joana Terés
- Plant Physiology Lab., Bioscience Faculty, Universidad Autónoma de Barcelona, 08193 Barcelona, Spain.
| | - Juan Barceló
- Plant Physiology Lab., Bioscience Faculty, Universidad Autónoma de Barcelona, 08193 Barcelona, Spain.
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9
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10
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Larkum AWD, Davey PA, Kuo J, Ralph PJ, Raven JA. Carbon-concentrating mechanisms in seagrasses. JOURNAL OF EXPERIMENTAL BOTANY 2017; 68:3773-3784. [PMID: 28911056 DOI: 10.1093/jxb/erx206] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Seagrasses are unique angiosperms that carry out growth and reproduction submerged in seawater. They occur in at least three families of the Alismatales. All have chloroplasts mainly in the cells of the epidermis. Living in seawater, the supply of inorganic carbon (Ci) to the chloroplasts is diffusion limited, especially under unstirred conditions. Therefore, the supply of CO2 and bicarbonate across the diffusive boundary layer on the outer side of the epidermis is often a limiting factor. Here we discuss the evidence for mechanisms that enhance the uptake of Ci into the epidermal cells. Since bicarbonate is plentiful in seawater, a bicarbonate pump might be expected; however, the evidence for such a pump is not strongly supported. There is evidence for a carbonic anhydrase outside the outer plasmalemma. This, together with evidence for an outward proton pump, suggests the possibility that local acidification leads to enhanced concentrations of CO2 adjacent to the outer tangential epidermal walls, which enhances the uptake of CO2, and this could be followed by a carbon-concentrating mechanism (CCM) in the cytoplasm and/or chloroplasts. The lines of evidence for such an epidermal CCM are discussed, including evidence for special 'transfer cells' in some but not all seagrass leaves in the tangential inner walls of the epidermal cells. It is concluded that seagrasses have a CCM but that the case for concentration of CO2 at the site of Rubisco carboxylation is not proven.
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Affiliation(s)
- Anthony William D Larkum
- Plant Functional Biology and Global Climate Change Cluster, University of Technology Sydney, NSW 2009, Australia
| | - Peter A Davey
- Plant Functional Biology and Global Climate Change Cluster, University of Technology Sydney, NSW 2009, Australia
| | - John Kuo
- Electron Microscope Centre, University of Western Australia, WA 6900, Australia
| | - Peter J Ralph
- Plant Functional Biology and Global Climate Change Cluster, University of Technology Sydney, NSW 2009, Australia
| | - John A Raven
- Plant Functional Biology and Global Climate Change Cluster, University of Technology Sydney, NSW 2009, Australia
- University of Dundee at JHI, Invergowrie, Dundee, UK
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11
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McClelland HLO, Bruggeman J, Hermoso M, Rickaby REM. The origin of carbon isotope vital effects in coccolith calcite. Nat Commun 2017; 8:14511. [PMID: 28262764 PMCID: PMC5343501 DOI: 10.1038/ncomms14511] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2016] [Accepted: 01/06/2017] [Indexed: 12/17/2022] Open
Abstract
Calcite microfossils are widely used to study climate and oceanography in Earth's geological past. Coccoliths, readily preserved calcite plates produced by a group of single-celled surface-ocean dwelling algae called coccolithophores, have formed a significant fraction of marine sediments since the Late Triassic. However, unlike the shells of foraminifera, their zooplankton counterparts, coccoliths remain underused in palaeo-reconstructions. Precipitated in an intracellular chemical and isotopic microenvironment, coccolith calcite exhibits large and enigmatic departures from the isotopic composition of abiogenic calcite, known as vital effects. Here we show that the calcification to carbon fixation ratio determines whether coccolith calcite is isotopically heavier or lighter than abiogenic calcite, and that the size of the deviation is determined by the degree of carbon utilization. We discuss the theoretical potential for, and current limitations of, coccolith-based CO2 paleobarometry, that may eventually facilitate use of the ubiquitous and geologically extensive sedimentary archive.
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Affiliation(s)
- H. L. O. McClelland
- Department of Earth Sciences, University of Oxford, South Parks Road, Oxford OX1 3AN, UK
- Department of Earth and Planetary Science, Washington University in St Louis, Campus box 1169, 1 Brookings Dr, St Louis, Missouri 63130, USA
| | - J. Bruggeman
- Plymouth Marine Laboratory, Prospect Place, The Hoe, Plymouth PL1 3DH, UK
| | - M. Hermoso
- Department of Earth Sciences, University of Oxford, South Parks Road, Oxford OX1 3AN, UK
- Équipe de Géochimie des Isotopes Stables, Institut de Physique du Globe de Paris, Sorbonne Paris Cité, Univ Paris Diderot, UMR 7154 CNRS, F-75005 Paris, France
| | - R. E. M. Rickaby
- Department of Earth Sciences, University of Oxford, South Parks Road, Oxford OX1 3AN, UK
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12
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Kottmeier DM, Rokitta SD, Rost B. Acidification, not carbonation, is the major regulator of carbon fluxes in the coccolithophore Emiliania huxleyi. THE NEW PHYTOLOGIST 2016; 211:126-37. [PMID: 26918275 PMCID: PMC5069628 DOI: 10.1111/nph.13885] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/13/2015] [Accepted: 01/06/2016] [Indexed: 05/11/2023]
Abstract
A combined increase in seawater [CO2 ] and [H(+) ] was recently shown to induce a shift from photosynthetic HCO3 (-) to CO2 uptake in Emiliania huxleyi. This shift occurred within minutes, whereas acclimation to ocean acidification (OA) did not affect the carbon source. To identify the driver of this shift, we exposed low- and high-light acclimated E. huxleyi to a matrix of two levels of dissolved inorganic carbon (1400, 2800 μmol kg(-1) ) and pH (8.15, 7.85) and directly measured cellular O2 , CO2 and HCO3 (-) fluxes under these conditions. Exposure to increased [CO2 ] had little effect on the photosynthetic fluxes, whereas increased [H(+) ] led to a significant decline in HCO3 (-) uptake. Low-light acclimated cells overcompensated for the inhibition of HCO3 (-) uptake by increasing CO2 uptake. High-light acclimated cells, relying on higher proportions of HCO3 (-) uptake, could not increase CO2 uptake and photosynthetic O2 evolution consequently became carbon-limited. These regulations indicate that OA responses in photosynthesis are caused by [H(+) ] rather than by [CO2 ]. The impaired HCO3 (-) uptake also provides a mechanistic explanation for lowered calcification under OA. Moreover, it explains the OA-dependent decrease in photosynthesis observed in high-light grown phytoplankton.
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Affiliation(s)
- Dorothee M. Kottmeier
- Alfred Wegener InstituteHelmholtz Centre for Polar and Marine ResearchAm Handelshafen 1227570BremerhavenGermany
| | - Sebastian D. Rokitta
- Alfred Wegener InstituteHelmholtz Centre for Polar and Marine ResearchAm Handelshafen 1227570BremerhavenGermany
| | - Björn Rost
- Alfred Wegener InstituteHelmholtz Centre for Polar and Marine ResearchAm Handelshafen 1227570BremerhavenGermany
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13
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Brownlee C, Wheeler GL, Taylor AR. Coccolithophore biomineralization: New questions, new answers. Semin Cell Dev Biol 2015; 46:11-6. [DOI: 10.1016/j.semcdb.2015.10.027] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2015] [Revised: 10/16/2015] [Accepted: 10/16/2015] [Indexed: 11/28/2022]
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Rautenberger R, Fernández PA, Strittmatter M, Heesch S, Cornwall CE, Hurd CL, Roleda MY. Saturating light and not increased carbon dioxide under ocean acidification drives photosynthesis and growth in Ulva rigida (Chlorophyta). Ecol Evol 2015; 5:874-88. [PMID: 25750714 PMCID: PMC4338970 DOI: 10.1002/ece3.1382] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2014] [Revised: 12/10/2014] [Accepted: 12/12/2014] [Indexed: 11/28/2022] Open
Abstract
Carbon physiology of a genetically identified Ulva rigida was investigated under different CO2(aq) and light levels. The study was designed to answer whether (1) light or exogenous inorganic carbon (Ci) pool is driving growth; and (2) elevated CO2(aq) concentration under ocean acidification (OA) will downregulate CAext-mediated [Formula: see text] dehydration and alter the stable carbon isotope (δ (13)C) signatures toward more CO2 use to support higher growth rate. At pHT 9.0 where CO2(aq) is <1 μmol L(-1), inhibition of the known [Formula: see text] use mechanisms, that is, direct [Formula: see text] uptake through the AE port and CAext-mediated [Formula: see text] dehydration decreased net photosynthesis (NPS) by only 56-83%, leaving the carbon uptake mechanism for the remaining 17-44% of the NPS unaccounted. An in silico search for carbon-concentrating mechanism elements in expressed sequence tag libraries of Ulva found putative light-dependent [Formula: see text] transporters to which the remaining NPS can be attributed. The shift in δ (13)C signatures from -22‰ toward -10‰ under saturating light but not under elevated CO2(aq) suggest preference and substantial [Formula: see text] use to support photosynthesis and growth. U. rigida is Ci saturated, and growth was primarily controlled by light. Therefore, increased levels of CO2(aq) predicted for the future will not, in isolation, stimulate Ulva blooms.
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Affiliation(s)
- Ralf Rautenberger
- Department of Botany, University of OtagoP.O. Box 56, Dunedin, 9054, New Zealand
| | - Pamela A Fernández
- Department of Botany, University of OtagoP.O. Box 56, Dunedin, 9054, New Zealand
| | - Martina Strittmatter
- The Scottish Association for Marine Science, Scottish Marine InstituteOban, Argyll, PA37 1QA, Scotland
| | - Svenja Heesch
- Irish Seaweed Research Group, Ryan Institute for Environmental, Marine and Energy Research, National University of IrelandGalway (NUIG), University Road, Galway, Ireland
| | - Christopher E Cornwall
- Department of Botany, University of OtagoP.O. Box 56, Dunedin, 9054, New Zealand
- Institute for Marine and Antarctic Studies, University of TasmaniaHobart, Tasmania, 7001, Australia
| | - Catriona L Hurd
- Department of Botany, University of OtagoP.O. Box 56, Dunedin, 9054, New Zealand
- Institute for Marine and Antarctic Studies, University of TasmaniaHobart, Tasmania, 7001, Australia
| | - Michael Y Roleda
- Department of Botany, University of OtagoP.O. Box 56, Dunedin, 9054, New Zealand
- Bioforsk Norwegian Institute for Agricultural and Environmental ResearchKudalsveien 6, 8049, Bodø, Norway
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15
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Holtz LM, Wolf-Gladrow D, Thoms S. Numerical cell model investigating cellular carbon fluxes in Emiliania huxleyi. J Theor Biol 2015; 364:305-15. [DOI: 10.1016/j.jtbi.2014.08.040] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2014] [Revised: 08/07/2014] [Accepted: 08/11/2014] [Indexed: 10/24/2022]
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Fernández PA, Hurd CL, Roleda MY. Bicarbonate uptake via an anion exchange protein is the main mechanism of inorganic carbon acquisition by the giant kelp Macrocystis pyrifera (Laminariales, Phaeophyceae) under variable pH. JOURNAL OF PHYCOLOGY 2014; 50:998-1008. [PMID: 26988782 DOI: 10.1111/jpy.12247] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/27/2014] [Accepted: 08/28/2014] [Indexed: 06/05/2023]
Abstract
Macrocystis pyrifera is a widely distributed, highly productive, seaweed. It is known to use bicarbonate (HCO3 (-) ) from seawater in photosynthesis and the main mechanism of utilization is attributed to the external catalyzed dehydration of HCO3 (-) by the surface-bound enzyme carbonic anhydrase (CAext ). Here, we examined other putative HCO3 (-) uptake mechanisms in M. pyrifera under pHT 9.00 (HCO3 (-) : CO2 = 940:1) and pHT 7.65 (HCO3 (-) : CO2 = 51:1). Rates of photosynthesis, and internal CA (CAint ) and CAext activity were measured following the application of AZ which inhibits CAext , and DIDS which inhibits a different HCO3 (-) uptake system, via an anion exchange (AE) protein. We found that the main mechanism of HCO3 (-) uptake by M. pyrifera is via an AE protein, regardless of the HCO3 (-) : CO2 ratio, with CAext making little contribution. Inhibiting the AE protein led to a 55%-65% decrease in photosynthetic rates. Inhibiting both the AE protein and CAext at pHT 9.00 led to 80%-100% inhibition of photosynthesis, whereas at pHT 7.65, passive CO2 diffusion supported 33% of photosynthesis. CAint was active at pHT 7.65 and 9.00, and activity was always higher than CAext , because of its role in dehydrating HCO3 (-) to supply CO2 to RuBisCO. Interestingly, the main mechanism of HCO3 (-) uptake in M. pyrifera was different than that in other Laminariales studied (CAext -catalyzed reaction) and we suggest that species-specific knowledge of carbon uptake mechanisms is required in order to elucidate how seaweeds might respond to future changes in HCO3 (-) :CO2 due to ocean acidification.
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Affiliation(s)
- Pamela A Fernández
- Department of Botany, University of Otago, PO Box 56, Dunedin, 9054, New Zealand
| | - Catriona L Hurd
- Department of Botany, University of Otago, PO Box 56, Dunedin, 9054, New Zealand
- Institute for Marine and Antarctic Studies (IMAS), University of Tasmania, Private Bag 129, Sandy Bay, Hobart, Tasmania, 7001, Australia
| | - Michael Y Roleda
- Department of Botany, University of Otago, PO Box 56, Dunedin, 9054, New Zealand
- Bioforsk Norwegian Institute for Agricultural and Environmental Research, Kudalsveien 6, Bodø, 8049, Norway
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17
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Kottmeier DM, Rokitta SD, Tortell PD, Rost B. Strong shift from HCO3 (-) to CO 2 uptake in Emiliania huxleyi with acidification: new approach unravels acclimation versus short-term pH effects. PHOTOSYNTHESIS RESEARCH 2014; 121:265-75. [PMID: 24563097 PMCID: PMC4077253 DOI: 10.1007/s11120-014-9984-9] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/07/2013] [Accepted: 02/10/2014] [Indexed: 05/07/2023]
Abstract
Effects of ocean acidification on Emiliania huxleyi strain RCC 1216 (calcifying, diploid life-cycle stage) and RCC 1217 (non-calcifying, haploid life-cycle stage) were investigated by measuring growth, elemental composition, and production rates under different pCO2 levels (380 and 950 μatm). In these differently acclimated cells, the photosynthetic carbon source was assessed by a (14)C disequilibrium assay, conducted over a range of ecologically relevant pH values (7.9-8.7). In agreement with previous studies, we observed decreased calcification and stimulated biomass production in diploid cells under high pCO2, but no CO2-dependent changes in biomass production for haploid cells. In both life-cycle stages, the relative contributions of CO2 and HCO3 (-) uptake depended strongly on the assay pH. At pH values ≤ 8.1, cells preferentially used CO2 (≥ 90 % CO2), whereas at pH values ≥ 8.3, cells progressively increased the fraction of HCO3 (-) uptake (~45 % CO2 at pH 8.7 in diploid cells; ~55 % CO2 at pH 8.5 in haploid cells). In contrast to the short-term effect of the assay pH, the pCO2 acclimation history had no significant effect on the carbon uptake behavior. A numerical sensitivity study confirmed that the pH-modification in the (14)C disequilibrium method yields reliable results, provided that model parameters (e.g., pH, temperature) are kept within typical measurement uncertainties. Our results demonstrate a high plasticity of E. huxleyi to rapidly adjust carbon acquisition to the external carbon supply and/or pH, and provide an explanation for the paradoxical observation of high CO2 sensitivity despite the apparently high HCO3 (-) usage seen in previous studies.
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Affiliation(s)
- Dorothee M Kottmeier
- Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research, Am Handelshafen 12, 27570, Bremerhaven, Germany,
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18
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Stojkovic S, Beardall J, Matear R. CO2 -concentrating mechanisms in three southern hemisphere strains of Emiliania huxleyi. JOURNAL OF PHYCOLOGY 2013; 49:670-9. [PMID: 27007199 DOI: 10.1111/jpy.12074] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/18/2012] [Accepted: 03/19/2013] [Indexed: 05/23/2023]
Abstract
Rising global CO2 is changing the carbonate chemistry of seawater, which is expected to influence the way phytoplankton acquire inorganic carbon. All phytoplankton rely on ribulose-bisphosphate carboxylase oxygenase (RUBISCO) for assimilation of inorganic carbon in photosynthesis, but this enzyme is inefficient at present day CO2 levels. Many algae have developed a range of energy demanding mechanisms, referred to as carbon concentrating mechanisms (CCMs), which increase the efficiency of carbon acquisition. We investigated CCM activity in three southern hemisphere strains of the coccolithophorid Emiliania huxleyi W. W. Hay & H. P. Mohler. Both calcifying and non-calcifying strains showed strong CCM activity, with HCO3 (-) as a preferred source of photosynthetic carbon in the non-calcifying strain, but a higher preference for CO2 in the calcifying strains. All three strains were characterized by the presence of pyrenoids, external carbonic anhydrase (CA) and high affinity for CO2 in photosynthesis, indicative of active CCMs. We postulate that under higher CO2 levels cocco-lithophorids will be able to down-regulate their CCMs, and re-direct some of the metabolic energy to processes such as calcification. Due to the expected rise in CO2 levels, photosynthesis in calcifying strains is expected to benefit most, due to their use of CO2 for carbon uptake. The non-calcifying strain, on the other hand, will experience only a 10% increase in HCO3 (-) , thus making it less responsive to changes in carbonate chemistry of water.
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Affiliation(s)
- Slobodanka Stojkovic
- CMAR--CSIRO, Hobart, Tas, 7001, Australia
- School of Biological Sciences, Monash University, Clayton, Vic., 3800, Australia
| | - John Beardall
- School of Biological Sciences, Monash University, Clayton, Vic., 3800, Australia
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Bach LT, Mackinder LCM, Schulz KG, Wheeler G, Schroeder DC, Brownlee C, Riebesell U. Dissecting the impact of CO2 and pH on the mechanisms of photosynthesis and calcification in the coccolithophore Emiliania huxleyi. THE NEW PHYTOLOGIST 2013; 199:121-134. [PMID: 23496417 DOI: 10.1111/nph.12225] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/10/2013] [Accepted: 02/08/2013] [Indexed: 05/15/2023]
Abstract
Coccolithophores are important calcifying phytoplankton predicted to be impacted by changes in ocean carbonate chemistry caused by the absorption of anthropogenic CO2 . However, it is difficult to disentangle the effects of the simultaneously changing carbonate system parameters (CO2 , bicarbonate, carbonate and protons) on the physiological responses to elevated CO2 . Here, we adopted a multifactorial approach at constant pH or CO2 whilst varying dissolved inorganic carbon (DIC) to determine physiological and transcriptional responses to individual carbonate system parameters. We show that Emiliania huxleyi is sensitive to low CO2 (growth and photosynthesis) and low bicarbonate (calcification) as well as low pH beyond a limited tolerance range, but is much less sensitive to elevated CO2 and bicarbonate. Multiple up-regulated genes at low DIC bear the hallmarks of a carbon-concentrating mechanism (CCM) that is responsive to CO2 and bicarbonate but not to pH. Emiliania huxleyi appears to have evolved mechanisms to respond to limiting rather than elevated CO2 . Calcification does not function as a CCM, but is inhibited at low DIC to allow the redistribution of DIC from calcification to photosynthesis. The presented data provides a significant step in understanding how E. huxleyi will respond to changing carbonate chemistry at a cellular level.
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Affiliation(s)
- Lennart T Bach
- Helmholtz-Zentrum für Ozeanforschung Kiel (GEOMAR), D-24105, Kiel, Germany
| | - Luke C M Mackinder
- Helmholtz-Zentrum für Ozeanforschung Kiel (GEOMAR), D-24105, Kiel, Germany
- Marine Biological Association of the UK, The Laboratory, Citadel Hill, Plymouth, PL1 2PB, UK
| | - Kai G Schulz
- Helmholtz-Zentrum für Ozeanforschung Kiel (GEOMAR), D-24105, Kiel, Germany
| | - Glen Wheeler
- Marine Biological Association of the UK, The Laboratory, Citadel Hill, Plymouth, PL1 2PB, UK
- Plymouth Marine Laboratory, Prospect Place, Plymouth, PL1 3DH, UK
| | - Declan C Schroeder
- Marine Biological Association of the UK, The Laboratory, Citadel Hill, Plymouth, PL1 2PB, UK
| | - Colin Brownlee
- Marine Biological Association of the UK, The Laboratory, Citadel Hill, Plymouth, PL1 2PB, UK
| | - Ulf Riebesell
- Helmholtz-Zentrum für Ozeanforschung Kiel (GEOMAR), D-24105, Kiel, Germany
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20
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21
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Raven JA, Hurd CL. Ecophysiology of photosynthesis in macroalgae. PHOTOSYNTHESIS RESEARCH 2012; 113:105-25. [PMID: 22843100 DOI: 10.1007/s11120-012-9768-z] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/12/2012] [Accepted: 07/04/2012] [Indexed: 05/07/2023]
Abstract
Macroalgae occur in the marine benthos from the upper intertidal to depths of more than 200 m, contributing up to 1 Pg C per year to global primary productivity. Freshwater macroalgae are mainly green (Chlorophyta) with some red (Rhodophyta) and a small contribution of brown (Phaeophyceae) algae, while in the ocean all three higher taxa are important. Attempts to relate the depth distribution of three higher taxa of marine macroalgae to their photosynthetic light use through their pigmentation in relation to variations in spectral quality of photosynthetically active radiation (PAR) with depth (complementary chromatic adaptation) and optical thickness (package effect) have been relatively unsuccessful. The presence (Chlorophyta, Phaeophyceae) or absence (Rhodophyta) of a xanthophyll cycle is also not well correlated with depth distribution of marine algae. The relative absence of freshwater brown algae does not seem to be related to their photosynthetic light use. Photosynthetic inorganic carbon acquisition in some red and a few green macroalgae involves entry of CO(2) by diffusion. Other red and green macroalgae, and brown macroalgae, have CO(2) concentrating mechanisms; these frequently involve acid and alkaline zones on the surface of the alga with CO(2) (produced from HCO(3) (-)) entering in the acid zones, while some macroalgae have CCMs based on active influx of HCO(3) (-). These various mechanisms of carbon acquisition have different responses to the thickness of the diffusion boundary layer, which is determined by macroalgal morphology and water velocity. Energetic predictions that macroalgae growing at or near the lower limit of PAR for growth should rely on diffusive CO(2) entry without acid and alkaline zones, and on NH(4) (+) rather than NO(3) (-) as nitrogen source, are only partially borne out by observation. The impact of global environmental change on marine macroalgae mainly relates to ocean acidification and warming with shoaling of the thermocline and decreased nutrient flux to the upper mixed layer. Predictions of the impact on macroalgae requires further experiments on interactions among increased inorganic carbon, increased temperature and decreased nitrogen and phosphorus supply, and, when possible, studies of genetic adaptation to environmental change.
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Affiliation(s)
- John A Raven
- Division of Plant Sciences, University of Dundee at the James Hutton Institute, Invergowrie, Dundee, DD2 5DA, Scotland, UK.
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22
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Xu K, Gao K. Reduced calcification decreases photoprotective capability in the coccolithophorid Emiliania huxleyi. PLANT & CELL PHYSIOLOGY 2012; 53:1267-1274. [PMID: 22555817 DOI: 10.1093/pcp/pcs066] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Intracellular calcification of coccolithophores generates CO₂ and consumes additional energy for acquisition of calcium and bicarbonate ions; therefore, it may correlate with photoprotective processes by influencing the energetics. To address this hypothesis, a calcifying Emiliania huxleyi strain (CS-369) was grown semi-continuously at reduced (0.1 mM, LCa) and ambient Ca²⁺ concentrations (10 mM, HCa) for 150 d (>200 generations). The HCa-grown cells had higher photosynthetic and calcification rates and higher contents of Chl a and carotenoids compared with the naked (bearing no coccoliths) LCa-grown cells. When exposed to stressfull levels of photosynthetically active radiation (PAR), LCa-grown cells displayed lower photochemical yield and less efficient non-photochemical quenching (NPQ). When the LCa- or HCa-grown cells were inversely shifted to their counterpart medium, LCa to HCa transfer increased photosynthetic carbon fixation (P), calcification rate (C), the C/P ratio, NPQ and pigment contents, whereas those shifted from HCa to LCa exhibited the opposite effects. Increased NPQ, carotenoids and quantum yield were clearly linked with increased or sustained calcification in E. huxleyi. The calcification must have played a role in dissipating excessive energy or as an additional drainage of electrons absorbed by the photosynthetic antennae. This phenomenon was further supported by testing two non-calcifying strains, which showed insignificant changes in photosynthetic carbon fixation and NPQ when transferred to LCa conditions.
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Affiliation(s)
- Kai Xu
- State Key Laboratory of Marine Environmental Science, Xiamen University, Xiamen 361005, PR China
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23
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McCarthy A, Rogers SP, Duffy SJ, Campbell DA. ELEVATED CARBON DIOXIDE DIFFERENTIALLY ALTERS THE PHOTOPHYSIOLOGY OF THALASSIOSIRA PSEUDONANA (BACILLARIOPHYCEAE) AND EMILIANIA HUXLEYI (HAPTOPHYTA)(1). JOURNAL OF PHYCOLOGY 2012; 48:635-646. [PMID: 27011079 DOI: 10.1111/j.1529-8817.2012.01171.x] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Increasing anthropogenic carbon dioxide is causing changes to ocean chemistry, which will continue in a predictable manner. Dissolution of additional atmospheric carbon dioxide leads to increased concentrations of dissolved carbon dioxide and bicarbonate and decreased pH in ocean water. The concomitant effects on phytoplankton ecophysiology, leading potentially to changes in community structure, are now a focus of concern. Therefore, we grew the coccolithophore Emiliania huxleyi (Lohmann) W. W. Hay et H. Mohler and the diatom strains Thalassiosira pseudonana (Hust.) Hasle et Heimdal CCMP 1014 and T. pseudonana CCMP 1335 under low light in turbidostat photobioreactors bubbled with air containing 390 ppmv or 750 ppmv CO2 . Increased pCO2 led to increased growth rates in all three strains. In addition, protein levels of RUBISCO increased in the coastal strains of both species, showing a larger capacity for CO2 assimilation at 750 ppmv CO2 . With increased pCO2 , both T. pseudonana strains displayed an increased susceptibility to PSII photoinactivation and, to compensate, an augmented capacity for PSII repair. Consequently, the cost of maintaining PSII function for the diatoms increased at increased pCO2 . In E. huxleyi, PSII photoinactivation and the counter-acting repair, while both intrinsically larger than in T. pseudonana, did not change between the current and high-pCO2 treatments. The content of the photosynthetic electron transport intermediary cytochrome b6/f complex increased significantly in the diatoms under elevated pCO2 , suggesting changes in electron transport function.
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Affiliation(s)
- Avery McCarthy
- Department of Chemistry & Biochemistry, Mount Allison University, Sackville, New Brunswick, E4L 1G7, Canada
| | - Susan P Rogers
- Department of Chemistry & Biochemistry, Mount Allison University, Sackville, New Brunswick, E4L 1G7, Canada
| | - Stephen J Duffy
- Department of Chemistry & Biochemistry, Mount Allison University, Sackville, New Brunswick, E4L 1G7, Canada
| | - Douglas A Campbell
- Department of Chemistry & Biochemistry, Mount Allison University, Sackville, New Brunswick, E4L 1G7, Canada
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Moolna A, Rickaby REM. Interaction of the coccolithophore Gephyrocapsa oceanica with its carbon environment: response to a recreated high-CO2 geological past. GEOBIOLOGY 2012; 10:72-81. [PMID: 22118223 DOI: 10.1111/j.1472-4669.2011.00308.x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Coccolithophores have played a key role in the carbon cycle since becoming dominant in the Cretaceous ocean, and their influence depends fundamentally on how they interact with their external carbon environment. Because the photosynthetic carbon-fixing enzyme Rubisco requires high levels of CO(2) for effective catalysis, coccolithophores are known to induce carbon concentrating mechanisms (CCMs) to raise the level of dissolved inorganic carbon (DIC) in an 'internal pool'. The ocean carbon system has varied greatly over the geological past, suggesting that coccolithophore interactions with that external carbon environment will have changed in parallel. The widespread present-day coccolithophore Gephyrocapsa oceanica was acclimated here to a geological scale change in the seawater carbon system (five times higher DIC and alkalinity). Significant acclimation in response to the external carbon environment was demonstrated by a fourfold increase in the K(m) substrate concentration requirement for half-maximum photosynthetic carbon fixation rates (suggesting that CCMs were down-regulated when ambient carbon was more available). There was, however, no difference in growth rate, morphology or calcification, suggesting that calcification is not coupled to photosynthesis as one of the CCMs induced here and that productivity (growth rate and calcification) is not carbon-limited under representative present-day conditions. Beyond the kinetic parameters of photosynthesis, the only other indication of changed cell physiology seen was the increased fractionation of carbon isotopes into organic matter. These findings demonstrate that G. oceanica changes its carbon-use physiology to maintain consistent photosynthetic carbon fixation in concert with different levels of ambient DIC without changing its morphology or calcification.
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Affiliation(s)
- A Moolna
- Department of Earth Sciences, University of Oxford, South Parks Road, Oxford, UK
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Mackinder L, Wheeler G, Schroeder D, von Dassow P, Riebesell U, Brownlee C. Expression of biomineralization-related ion transport genes in Emiliania huxleyi. Environ Microbiol 2011; 13:3250-65. [PMID: 21902794 DOI: 10.1111/j.1462-2920.2011.02561.x] [Citation(s) in RCA: 72] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Biomineralization in the marine phytoplankton Emiliania huxleyi is a stringently controlled intracellular process. The molecular basis of coccolith production is still relatively unknown although its importance in global biogeochemical cycles and varying sensitivity to increased pCO₂ levels has been well documented. This study looks into the role of several candidate Ca²⁺, H⁺ and inorganic carbon transport genes in E. huxleyi, using quantitative reverse transcriptase PCR. Differential gene expression analysis was investigated in two isogenic pairs of calcifying and non-calcifying strains of E. huxleyi and cultures grown at various Ca²⁺ concentrations to alter calcite production. We show that calcification correlated to the consistent upregulation of a putative HCO₃⁻ transporter belonging to the solute carrier 4 (SLC4) family, a Ca²⁺/H⁺ exchanger belonging to the CAX family of exchangers and a vacuolar H⁺-ATPase. We also show that the coccolith-associated protein, GPA is downregulated in calcifying cells. The data provide strong evidence that these genes play key roles in E. huxleyi biomineralization. Based on the gene expression data and the current literature a working model for biomineralization-related ion transport in coccolithophores is presented.
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Affiliation(s)
- Luke Mackinder
- The Laboratory, Marine Biological Association of the UK, Citadel Hill, Plymouth PL1 2PB, UK.
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26
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Taylor AR, Chrachri A, Wheeler G, Goddard H, Brownlee C. A voltage-gated H+ channel underlying pH homeostasis in calcifying coccolithophores. PLoS Biol 2011; 9:e1001085. [PMID: 21713028 PMCID: PMC3119654 DOI: 10.1371/journal.pbio.1001085] [Citation(s) in RCA: 121] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2010] [Accepted: 05/05/2011] [Indexed: 11/19/2022] Open
Abstract
Marine coccolithophorid phytoplankton are major producers of biogenic calcite, playing a significant role in the global carbon cycle. Predicting the impacts of ocean acidification on coccolithophore calcification has received much recent attention and requires improved knowledge of cellular calcification mechanisms. Uniquely amongst calcifying organisms, coccolithophores produce calcified scales (coccoliths) in an intracellular compartment and secrete them to the cell surface, requiring large transcellular ionic fluxes to support calcification. In particular, intracellular calcite precipitation using HCO₃⁻ as the substrate generates equimolar quantities of H+ that must be rapidly removed to prevent cytoplasmic acidification. We have used electrophysiological approaches to identify a plasma membrane voltage-gated H+ conductance in Coccolithus pelagicus ssp braarudii with remarkably similar biophysical and functional properties to those found in metazoans. We show that both C. pelagicus and Emiliania huxleyi possess homologues of metazoan H(v)1 H+ channels, which function as voltage-gated H+ channels when expressed in heterologous systems. Homologues of the coccolithophore H+ channels were also identified in a diversity of eukaryotes, suggesting a wide range of cellular roles for the H(v)1 class of proteins. Using single cell imaging, we demonstrate that the coccolithophore H+ conductance mediates rapid H+ efflux and plays an important role in pH homeostasis in calcifying cells. The results demonstrate a novel cellular role for voltage gated H+ channels and provide mechanistic insight into biomineralisation by establishing a direct link between pH homeostasis and calcification. As the coccolithophore H+ conductance is dependent on the trans-membrane H+ electrochemical gradient, this mechanism will be directly impacted by, and may underlie adaptation to, ocean acidification. The presence of this H+ efflux pathway suggests that there is no obligate use of H+ derived from calcification for intracellular CO₂ generation. Furthermore, the presence of H(v)1 class ion channels in a wide range of extant eukaryote groups indicates they evolved in an early common ancestor.
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Affiliation(s)
- Alison R. Taylor
- The Marine Biological Association, The Laboratory, Citadel Hill, Plymouth, United Kingdom
- Department of Biology and Marine Biology, University of North Carolina Wilmington, Wilmington, North Carolina, United States of America
| | - Abdul Chrachri
- The Marine Biological Association, The Laboratory, Citadel Hill, Plymouth, United Kingdom
| | - Glen Wheeler
- The Marine Biological Association, The Laboratory, Citadel Hill, Plymouth, United Kingdom
- Plymouth Marine Laboratory, Prospect Place, The Hoe, Plymouth, United Kingdom
| | - Helen Goddard
- The Marine Biological Association, The Laboratory, Citadel Hill, Plymouth, United Kingdom
| | - Colin Brownlee
- The Marine Biological Association, The Laboratory, Citadel Hill, Plymouth, United Kingdom
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27
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Suffrian K, Schulz KG, Gutowska MA, Riebesell U, Bleich M. Cellular pH measurements in Emiliania huxleyi reveal pronounced membrane proton permeability. THE NEW PHYTOLOGIST 2011; 190:595-608. [PMID: 21294736 DOI: 10.1111/j.1469-8137.2010.03633.x] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
• To understand the influence of changing surface ocean pH and carbonate chemistry on the coccolithophore Emiliania huxleyi, it is necessary to characterize mechanisms involved in pH homeostasis and ion transport. • Here, we measured effects of changes in seawater carbonate chemistry on the fluorescence emission ratio of BCECF (2',7'-bis-(2-carboxyethyl)-5-(and-6)-carboxyfluorescein) as a measure of intracellular pH (pH(i)). Out of equilibrium solutions were used to differentiate between membrane permeation pathways for H(+), CO(2) and HCO(3)(-). • Changes in fluorescence ratio were calibrated in single cells, resulting in a ratio change of 0.78 per pH(i) unit. pH(i) acutely followed the pH of seawater (pH(e)) in a linear fashion between pH(e) values of 6.5 and 9 with a slope of 0.44 per pH(e) unit. pH(i) was nearly insensitive to changes in seawater CO(2) at constant pH(e) and HCO(3)(-). An increase in extracellular HCO(3)(-) resulted in a slight intracellular acidification. In the presence of DIDS (4,4'-diisothiocyanatostilbene-2,2'-disulfonic acid), a broad-spectrum inhibitor of anion exchangers, E. huxleyi acidified irreversibly. DIDS slightly reduced the effect of pH(e) on pH(i). • The data for the first time show the occurrence of a proton permeation pathway in E. huxleyi plasma membrane. pH(i) homeostasis involves a DIDS-sensitive mechanism.
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Affiliation(s)
- K Suffrian
- Physiologisches Institut, CAU Kiel, Kiel, Germany
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28
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Moheimani NR, Borowitzka MA. Increased CO2 and the effect of pH on growth and calcification of Pleurochrysis carterae and Emiliania huxleyi (Haptophyta) in semicontinuous cultures. Appl Microbiol Biotechnol 2011; 90:1399-407. [PMID: 21369804 DOI: 10.1007/s00253-011-3174-x] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2010] [Revised: 02/01/2011] [Accepted: 02/09/2011] [Indexed: 11/29/2022]
Abstract
The effects of changes in CO(2) and pH on biomass productivity and carbon uptake of Pleurochrysis carterae and Emiliania huxleyi in open raceway ponds and a plate photobioreactor were studied. The pH of P. carterae cultures increased during day and decreased at night, whereas the pH of E. huxleyi cultures showed no significant diurnal changes. P. carterae coccolith production occurs during the dark period, whereas in E. huxleyi, coccolith production is mainly during the day. Addition of CO(2) at constant pH (pH-stat) resulted in an increase in P. carterae biomass and coccolith productivity, while CO(2) addition lowered E. huxleyi biomass and coccolith production. Neither of these algae could grow at less than pH 7.5. Species-specific diurnal pH and pCO(2) variations could be indicative of significant differences in carbon uptake between these two species. While E. huxleyi has been suggested to be predominantly a bicarbonate user, our results indicate that P. carterae may be using CO(2) as the main C source for photosynthesis and calcification.
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Affiliation(s)
- Navid R Moheimani
- Algae R&D Centre, School of Biological Sciences & Biotechnology, Murdoch University, Murdoch, WA, Australia.
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29
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Richier S, Fiorini S, Kerros ME, von Dassow P, Gattuso JP. Response of the calcifying coccolithophore Emiliania huxleyi to low pH/high pCO 2: from physiology to molecular level. MARINE BIOLOGY 2010; 158:551-560. [PMID: 24391258 PMCID: PMC3873069 DOI: 10.1007/s00227-010-1580-8] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/29/2010] [Accepted: 11/03/2010] [Indexed: 05/10/2023]
Abstract
The emergence of ocean acidification as a significant threat to calcifying organisms in marine ecosystems creates a pressing need to understand the physiological and molecular mechanisms by which calcification is affected by environmental parameters. We report here, for the first time, changes in gene expression induced by variations in pH/pCO2 in the widespread and abundant coccolithophore Emiliania huxleyi. Batch cultures were subjected to increased partial pressure of CO2 (pCO2; i.e. decreased pH), and the changes in expression of four functional gene classes directly or indirectly related to calcification were investigated. Increased pCO2 did not affect the calcification rate and only carbonic anhydrase transcripts exhibited a significant down-regulation. Our observation that elevated pCO2 induces only limited changes in the transcription of several transporters of calcium and bicarbonate gives new significant elements to understand cellular mechanisms underlying the early response of E. huxleyi to CO2-driven ocean acidification.
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Affiliation(s)
- Sophie Richier
- />INSU-CNRS, Laboratoire d’Océanographie de Villefranche, B.P. 28, 06234 Villefranche-sur-mer Cedex, France
- />UPMC University of Paris 06, Observatoire Océanologique de Villefranche, 06230 Villefranche-sur-mer, France
- />National Oceanography Centre, Southampton, University of Southampton Waterfront Campus, European Way, Southampton, SO14 3ZH UK
| | - Sarah Fiorini
- />INSU-CNRS, Laboratoire d’Océanographie de Villefranche, B.P. 28, 06234 Villefranche-sur-mer Cedex, France
- />UPMC University of Paris 06, Observatoire Océanologique de Villefranche, 06230 Villefranche-sur-mer, France
- />Netherlands Institute of Ecology (NIOO-KNAW), P.O. Box 140, 4400 AC Yerseke, The Netherlands
| | - Marie-Emmanuelle Kerros
- />INSU-CNRS, Laboratoire d’Océanographie de Villefranche, B.P. 28, 06234 Villefranche-sur-mer Cedex, France
- />UPMC University of Paris 06, Observatoire Océanologique de Villefranche, 06230 Villefranche-sur-mer, France
| | - Peter von Dassow
- />Departamento de Ecología, Facultad de Ciencias Biológicas, Pontificia Universidad Catolica de Chile, Alameda #340, Santiago, Chile
| | - Jean-Pierre Gattuso
- />INSU-CNRS, Laboratoire d’Océanographie de Villefranche, B.P. 28, 06234 Villefranche-sur-mer Cedex, France
- />UPMC University of Paris 06, Observatoire Océanologique de Villefranche, 06230 Villefranche-sur-mer, France
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30
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Leonardos N, Read B, Thake B, Young JR. NO MECHANISTIC DEPENDENCE OF PHOTOSYNTHESIS ON CALCIFICATION IN THE COCCOLITHOPHORID EMILIANIA HUXLEYI (HAPTOPHYTA)(1). JOURNAL OF PHYCOLOGY 2009; 45:1046-1051. [PMID: 27032349 DOI: 10.1111/j.1529-8817.2009.00726.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
There is still considerable uncertainty about the relationship between calcification and photosynthesis. It has been suggested that since calcification in coccolithophorids is an intracellular process that releases CO2 , it enhances photosynthesis in a manner analogous to a carbon-concentrating mechanism (CCM). The ubiquitous, bloom-forming, and numerically abundant coccolithophorid Emiliania huxleyi (Lohmann) W. W. Hay et H. Mohler was studied in nutrient-replete, pH and [CO2 ] controlled, continuous cultures (turbidostats) under a range of [Ca(2+) ] from 0 to 9 mM. We examined the long-term, fully acclimated photosynthesis-light responses and analyzed the crystalline structure of the coccoliths using SEM. The E. huxleyi cells completely lost their coccosphere when grown in 0 [Ca(2+) ], while thin, undercalcified and brittle coccoliths were evident at 1 mM [Ca(2+) ]. Coccoliths showed increasing levels of calcification with increasing [Ca(2+) ]. More robust coccoliths were noted, with no discernable differences in coccolith morphology when the cells were grown in either 5 or 9 mM (ambient seawater) [Ca(2+) ]. In contrast to calcification, photosynthesis was not affected by the [Ca(2+) ] in the media. Cells showed no correlation of their light-dependent O2 evolution with [Ca(2+) ], and in all [Ca(2+) ]-containing turbidostats, there were no significant differences in growth rate. The results show unequivocally that as a process, photosynthesis in E. huxleyi is mechanistically independent from calcification.
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Affiliation(s)
- Nikos Leonardos
- Department of Biological Sciences, University of Essex, Colchester, Essex CO4 3SQ, UKDepartment of Biological Sciences, California State University San Marcos, San Marcos, California 92096, USASchool of Biological and Chemical Sciences, Queen Mary, University of London, Mile End Road, London E1 4NS, UKNatural History Museum, Cromwell Road, London SW7 5BD, UK
| | - Betsy Read
- Department of Biological Sciences, University of Essex, Colchester, Essex CO4 3SQ, UKDepartment of Biological Sciences, California State University San Marcos, San Marcos, California 92096, USASchool of Biological and Chemical Sciences, Queen Mary, University of London, Mile End Road, London E1 4NS, UKNatural History Museum, Cromwell Road, London SW7 5BD, UK
| | - Brenda Thake
- Department of Biological Sciences, University of Essex, Colchester, Essex CO4 3SQ, UKDepartment of Biological Sciences, California State University San Marcos, San Marcos, California 92096, USASchool of Biological and Chemical Sciences, Queen Mary, University of London, Mile End Road, London E1 4NS, UKNatural History Museum, Cromwell Road, London SW7 5BD, UK
| | - Jeremy R Young
- Department of Biological Sciences, University of Essex, Colchester, Essex CO4 3SQ, UKDepartment of Biological Sciences, California State University San Marcos, San Marcos, California 92096, USASchool of Biological and Chemical Sciences, Queen Mary, University of London, Mile End Road, London E1 4NS, UKNatural History Museum, Cromwell Road, London SW7 5BD, UK
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31
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Carrasco M, Mercado JM, Niell FX. Diversity of inorganic carbon acquisition mechanisms by intact microbial mats of Microcoleus chthonoplastes (Cyanobacteriae, Oscillatoriaceae). PHYSIOLOGIA PLANTARUM 2008; 133:49-58. [PMID: 18405333 DOI: 10.1111/j.1399-3054.2007.01032.x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
Abstract
The dissolved inorganic carbon (DIC) acquisition mechanisms were researched in intact microbial mats dominated by the cyanobacteria Microcoleus chthonoplastes Thuret, by determining the effect on photosynthesis of different inhibitors. The microbial mats exhibited high affinity for DIC at alkaline pH, with K(m(DIC)) values similar to the ones described for pure cultures of cyanobacteria and algae in which carbon concentrating mechanisms have been researched. Besides, the photosynthesis was non-sensitive to pH changes within the range of 5.6-9.6, indicating that HCO(3)(-) was the main DIC source used for photosynthesis. The M. chthonoplastes mats featured external and internal carbonic anhydrase (CA) activity as measured in intact cells and cell extracts, respectively. Acetazolamide (AZ, which slowly enters the cell and then inhibits mainly the external CA) and ethoxyzolamide (EZ, which inhibits both external and internal CA) reduced significantly the oxygen evolution rates, demonstrating that the CA was implied in the DIC acquisition. Vanadate inhibited photosynthesis by 60% although its application, when CA being inhibited (i.e. after applying AZ + EZ), did not produce any additional effect. It could indicate that ATPase-dependent HCO(3)(-) use occurred and also that this putative mechanism was coupled with CA-like activity at the plasma membrane. The involvement of Na(+)-dependent HCO(3)(-) transporters in DIC acquisition was also inferred as monensin and 4-4'-diisothiocyanatostibilene-2,2'-disulfonate (DIDS) reduced photosynthesis by 70%. DIDS produced a strong inhibitory effect even after application of AZ + EZ + vanadate, indicating that this mechanism was not related to CA activity. The microbial mats become subject to very unfavourable conditions for Rubisco carboxylation at their natural habitats (e.g. external pH of 10.5 and O(2) concentration doubled with respect to saturation concentration); therefore, this putative diversity of DIC acquisition mechanisms could ensure their growth under these extreme conditions.
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Affiliation(s)
- María Carrasco
- Department of Ecology, Faculty of Science, University of Málaga, Campus de Teatinos s/n, 29070, Spain
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32
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Ripley SJ, Baker AC, Miller PI, Walne AW, Schroeder DC. Development and validation of a molecular technique for the analysis of archived formalin-preserved phytoplankton samples permits retrospective assessment of Emiliania huxleyi communities. J Microbiol Methods 2008; 73:118-24. [DOI: 10.1016/j.mimet.2008.02.001] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2007] [Revised: 01/28/2008] [Accepted: 02/05/2008] [Indexed: 10/22/2022]
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33
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Herfort L, Thake B, Taubner I. BICARBONATE STIMULATION OF CALCIFICATION AND PHOTOSYNTHESIS IN TWO HERMATYPIC CORALS(1). JOURNAL OF PHYCOLOGY 2008; 44:91-98. [PMID: 27041045 DOI: 10.1111/j.1529-8817.2007.00445.x] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
A wide range of bicarbonate concentrations was used to monitor the kinetics of bicarbonate (HCO3 (-) ) use in both photosynthesis and calcification in two reef-building corals, Porites porites and Acropora sp. Experiments carried out close to the P. porites collection site in Barbados showed that additions of NaHCO3 to synthetic seawater proportionally increased the calcification rate of this coral until the concentration exceeded three times that of seawater (6 mM). Photosynthetic rates were also stimulated by HCO3 (-) addition, but these became saturated at a lower concentration (4 mM). Similar experiments on aquarium-acclimated colonies of Indo-Pacific Acropora sp. showed that calcification and photosynthesis in this coral were enhanced to an even greater extent than P. porites, with calcification continuing to increase above 8 mM HCO3 (-) , and photosynthesis saturating at 6 mM. Calcification rates of Acropora sp. were also monitored in the dark, and, although these were lower than in the light for a given HCO3 (-) concentration, they still increased dramatically with HCO3 (-) addition, showing that calcification in this coral is light stimulated but not light dependent.
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Affiliation(s)
- Lydie Herfort
- School of Biological and Chemical Sciences, Queen Mary, University of London, Mile End Road, London E1 4NS, UK
| | - Brenda Thake
- School of Biological and Chemical Sciences, Queen Mary, University of London, Mile End Road, London E1 4NS, UK
| | - Isabelle Taubner
- School of Biological and Chemical Sciences, Queen Mary, University of London, Mile End Road, London E1 4NS, UK
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34
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Surface-water chemistry and fertility variations in the tropical Atlantic across the Paleocene/Eocene Thermal Maximum as evidenced by calcareous nannoplankton from ODP Leg 207, Hole 1259B. ACTA ACUST UNITED AC 2006. [DOI: 10.1016/j.revmic.2006.10.002] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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35
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Herfort L, Loste E, Meldrum F, Thake B. Structural and physiological effects of calcium and magnesium in Emiliania huxleyi (Lohmann) Hay and Mohler. J Struct Biol 2004; 148:307-14. [PMID: 15522779 DOI: 10.1016/j.jsb.2004.07.005] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2004] [Revised: 07/18/2004] [Indexed: 11/29/2022]
Abstract
In organisms which perform both photosynthesis and calcification, the fact that calcification proceeds faster in the light than in the dark has led to the long-established view that photosynthesis and calcification are closely coupled. It is now clear that calcification does not promote photosynthesis, but an enhancement of calcification by photosynthesis could still explain why calcification is faster in the light. To test this, the kinetics of the two processes were monitored over a wide range of calcium concentrations (0-50 mM) in the coccolithophore Emiliania huxleyi. The addition of 50 mM calcium strongly inhibited both processes, but when incubated in lower concentrations, rates of calcification increased up to 20 mM calcium whilst those of photosynthesis remained constant over the same range of calcium concentrations. So, rates of calcification are able to rise without a concomitant increase in photosynthetic rates. In addition, calcification rate and coccolith morphology responded similarly to changes in calcium concentrations; low calcification rates were associated with poor coccolith structure (undercalcification) and high calcification rates with perfectly formed coccoliths. Calcium concentration thus strongly influences calcification affecting both crystal structure and rate of calcite deposition. A similar structural analysis of coccoliths from cells grown in different magnesium concentrations showed that this ion is also essential for calcification, since strong signs of coccolith malformation and undercalcification were apparent at both low and high magnesium concentrations. In contrast with the calcium results, coccoliths were flawless only in the normal seawater concentration of 58 mM magnesium. We conclude that photosynthesis and calcification are not closely coupled and that calcification depends on a precise balance of both calcium and magnesium concentrations.
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Affiliation(s)
- Lydie Herfort
- School of Biological Sciences, Queen Mary, University of London, Mile End Road, London E1 4NS, UK
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36
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Shiraiwa Y. Physiological regulation of carbon fixation in the photosynthesis and calcification of coccolithophorids. Comp Biochem Physiol B Biochem Mol Biol 2003; 136:775-83. [PMID: 14662302 DOI: 10.1016/s1096-4959(03)00221-5] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Emiliania huxleyi and Gephyrocapsa oceanica are the predominant coccolithophorid species that produce blooms in the ocean and affect the global environment. These species are capable of carbon fixation by both photosynthesis for organic matter production and by intracellular calcification for coccolith production. Both processes were strongly affected by the nutrient status in a laboratory culture. The coccolith production was stimulated by the addition of a high concentration of sodium bicarbonate and by the depletion of phosphate. Interestingly, when the calcification was stimulated, the increase in cell number during algal growth was greatly suppressed and then the cell volume increased. When the growth rate was increased under nutrient-sufficient conditions, the cells became very small in size and most of them bore few or no coccoliths. The data from laboratory experiments show that the cell growth and calcification proceeded apparently independently at different phases. We, therefore, assume that the coccolithophorid blooms in the ocean might be separated into two phases; firstly, the increase in cell population might be triggered by an adequate supply of nutrients to enhance algal growth and then the calcification might subsequently be stimulated when the nutrients become depleted by substantial algal growth.
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Affiliation(s)
- Yoshihiro Shiraiwa
- Institute of Biological Sciences, University of Tsukuba, Tennoudai, Tsukuba 305-8572, Japan.
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