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Torres-Romero I, Zhang H, Wijker RS, Clark AJ, McLeod RE, Jaggi M, Stoll HM. Hydrogen isotope fractionation is controlled by CO 2 in coccolithophore lipids. Proc Natl Acad Sci U S A 2024; 121:e2318570121. [PMID: 38905238 PMCID: PMC11214045 DOI: 10.1073/pnas.2318570121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2023] [Accepted: 05/21/2024] [Indexed: 06/23/2024] Open
Abstract
Hydrogen isotope ratios (δ2H) represent an important natural tracer of metabolic processes, but quantitative models of processes controlling H-fractionation in aquatic photosynthetic organisms are lacking. Here, we elucidate the underlying physiological controls of 2H/1H fractionation in algal lipids by systematically manipulating temperature, light, and CO2(aq) in continuous cultures of the haptophyte Gephyrocapsa oceanica. We analyze the hydrogen isotope fractionation in alkenones (αalkenone), a class of acyl lipids specific to this species and other haptophyte algae. We find a strong decrease in the αalkenone with increasing CO2(aq) and confirm αalkenone correlates with temperature and light. Based on the known biosynthesis pathways, we develop a cellular model of the δ2H of algal acyl lipids to evaluate processes contributing to these controls on fractionation. Simulations show that longer residence times of NADPH in the chloroplast favor a greater exchange of NADPH with 2H-richer intracellular water, increasing αalkenone. Higher chloroplast CO2(aq) and temperature shorten NADPH residence time by enhancing the carbon fixation and lipid synthesis rates. The inverse correlation of αalkenone to CO2(aq) in our cultures suggests that carbon concentrating mechanisms (CCM) do not achieve a constant saturation of CO2 at the Rubisco site, but rather that chloroplast CO2 varies with external CO2(aq). The pervasive inverse correlation of αalkenone with CO2(aq) in the modern and preindustrial ocean also suggests that natural populations may not attain a constant saturation of Rubisco with the CCM. Rather than reconstructing growth water, αalkenone may be a powerful tool to elucidate the carbon limitation of photosynthesis.
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Affiliation(s)
- Ismael Torres-Romero
- Climate Geology, Department of Earth Sciences, ETH Zürich, Zurich8092, Switzerland
| | - Hongrui Zhang
- Climate Geology, Department of Earth Sciences, ETH Zürich, Zurich8092, Switzerland
| | - Reto S. Wijker
- Climate Geology, Department of Earth Sciences, ETH Zürich, Zurich8092, Switzerland
| | - Alexander J. Clark
- Climate Geology, Department of Earth Sciences, ETH Zürich, Zurich8092, Switzerland
| | - Rachel E. McLeod
- Climate Geology, Department of Earth Sciences, ETH Zürich, Zurich8092, Switzerland
| | - Madalina Jaggi
- Climate Geology, Department of Earth Sciences, ETH Zürich, Zurich8092, Switzerland
| | - Heather M. Stoll
- Climate Geology, Department of Earth Sciences, ETH Zürich, Zurich8092, Switzerland
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Wu R, Wu Y, Zhai R, Gao K, Xu J. Ocean acidification and desalination increase the growth and photosynthesis of the diatom Skeletonema costatum isolated from the coastal water of the Yellow Sea. MARINE ENVIRONMENTAL RESEARCH 2024; 197:106450. [PMID: 38552454 DOI: 10.1016/j.marenvres.2024.106450] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/16/2023] [Revised: 02/17/2024] [Accepted: 03/11/2024] [Indexed: 04/20/2024]
Abstract
Global climate changes induce substantial alterations in the marine system, including ocean acidification (OA), desalination and warming of surface seawater. Here, we examined the combined effects of OA and reduced salinity under different temperatures on the growth and photosynthesis of the diatom Skeletonema costatum. After having been acclimated to 2 CO2 concentrations (400 μatm, 1000 μatm) and 2 salinity levels (20 psu, 30 psu) at temperature levels of 10 °C and 20 °C, the diatom showed enhanced growth rate at the lowered salinity and elevated pCO2 irrespective of the temperature. The OA treatment increased the net photosynthetic rate and biogenic silica (Bsi) contents. Increasing the temperature from 10 to 20 °C raised the net photosynthetic rate by over twofold. The elevated pCO2 increased the net and gross photosynthetic rates by 20%-40% and by 16%-32%, respectively, with the higher enhancement observed at the higher levels of salinity and temperature. Our results imply that OA and desalination along with warming to the levels tested can enhance S. costatum's competitiveness in coastal phytoplankton communities under influence of future climate changes.
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Affiliation(s)
- Ruijie Wu
- Jiangsu Key Laboratory of Marine Bioresources and Environment/Jiangsu Key Laboratory of Marine Biotechnology, Jiangsu Ocean University, Lianyungang 222005, China
| | - Yuchen Wu
- Jiangsu Key Laboratory of Marine Bioresources and Environment/Jiangsu Key Laboratory of Marine Biotechnology, Jiangsu Ocean University, Lianyungang 222005, China
| | - Rui Zhai
- Jiangsu Key Laboratory of Marine Bioresources and Environment/Jiangsu Key Laboratory of Marine Biotechnology, Jiangsu Ocean University, Lianyungang 222005, China
| | - Kunshan Gao
- State Key Laboratory of Marine Environmental Science, College of Ocean and Earth Sciences, Xiamen University, Xiamen 361005, China
| | - Juntian Xu
- Jiangsu Key Laboratory of Marine Bioresources and Environment/Jiangsu Key Laboratory of Marine Biotechnology, Jiangsu Ocean University, Lianyungang 222005, China; Key Laboratory of Coastal Salt Marsh Ecosystems and Resources, Ministry of Natural Resources, Jiangsu Ocean University, Lianyungang 222005, China.
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3
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Keys M, Hopkinson B, Highfield A, Chrachri A, Brownlee C, Wheeler GL. The requirement for external carbonic anhydrase in diatoms is influenced by the supply and demand for dissolved inorganic carbon. JOURNAL OF PHYCOLOGY 2024; 60:29-45. [PMID: 38127095 DOI: 10.1111/jpy.13416] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/25/2023] [Revised: 09/28/2023] [Accepted: 11/15/2023] [Indexed: 12/23/2023]
Abstract
Photosynthesis by marine diatoms contributes significantly to the global carbon cycle. Due to the low concentration of CO2 in seawater, many diatoms use extracellular carbonic anhydrase (eCA) to enhance the supply of CO2 to the cell surface. While much research has investigated how the requirement for eCA is influenced by changes in CO2 availability, little is known about how eCA contributes to CO2 supply following changes in the demand for carbon. We therefore examined how changes in photosynthetic rate influence the requirement for eCA in three centric diatoms. Modeling of cell surface carbonate chemistry indicated that diffusive CO2 supply to the cell surface was greatly reduced in large diatoms at higher photosynthetic rates. Laboratory experiments demonstrated a trend of an increasing requirement for eCA with increasing photosynthetic rate that was most pronounced in the larger species, supporting the findings of the cellular modeling. Microelectrode measurements of cell surface pH and O2 demonstrated that individual cells exhibited an increased contribution of eCA to photosynthesis at higher irradiances. Our data demonstrate that changes in carbon demand strongly influence the requirement for eCA in diatoms. Cell size and photosynthetic rate will therefore be key determinants of the mode of dissolved inorganic carbon uptake.
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Affiliation(s)
- Matthew Keys
- Marine Biological Association, The Laboratory, Plymouth, UK
| | - Brian Hopkinson
- Department of Marine Sciences, University of Georgia, Athens, Georgia, USA
| | | | - Abdul Chrachri
- Marine Biological Association, The Laboratory, Plymouth, UK
| | - Colin Brownlee
- Marine Biological Association, The Laboratory, Plymouth, UK
| | - Glen L Wheeler
- Marine Biological Association, The Laboratory, Plymouth, UK
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Li M, Young JN. Temperature sensitivity of carbon concentrating mechanisms in the diatom Phaeodactylum tricornutum. PHOTOSYNTHESIS RESEARCH 2023; 156:205-215. [PMID: 36881356 PMCID: PMC10154264 DOI: 10.1007/s11120-023-01004-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/30/2022] [Accepted: 02/10/2023] [Indexed: 05/03/2023]
Abstract
Marine diatoms are key primary producers across diverse habitats in the global ocean. Diatoms rely on a biophysical carbon concentrating mechanism (CCM) to supply high concentrations of CO2 around their carboxylating enzyme, RuBisCO. The necessity and energetic cost of the CCM are likely to be highly sensitive to temperature, as temperature impacts CO2 concentration, diffusivity, and the kinetics of CCM components. Here, we used membrane inlet mass spectrometry (MIMS) and modeling to capture temperature regulation of the CCM in the diatom Phaeodactylum tricornutum (Pt). We found that enhanced carbon fixation rates by Pt at elevated temperatures were accompanied by increased CCM activity capable of maintaining RuBisCO close to CO2 saturation but that the mechanism varied. At 10 and 18 °C, diffusion of CO2 into the cell, driven by Pt's 'chloroplast pump' was the major inorganic carbon source. However, at 18 °C, upregulation of the chloroplast pump enhanced (while retaining the proportion of) both diffusive CO2 and active HCO3- uptake into the cytosol, and significantly increased chloroplast HCO3- concentrations. In contrast, at 25 °C, compared to 18 °C, the chloroplast pump had only a slight increase in activity. While diffusive uptake of CO2 into the cell remained constant, active HCO3- uptake across the cell membrane increased resulting in Pt depending equally on both CO2 and HCO3- as inorganic carbon sources. Despite changes in the CCM, the overall rate of active carbon transport remained double that of carbon fixation across all temperatures tested. The implication of the energetic cost of the Pt CCM in response to increasing temperatures was discussed.
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Affiliation(s)
- Meng Li
- School of Oceanography, University of Washington, Seattle, WA, USA
| | - Jodi N Young
- School of Oceanography, University of Washington, Seattle, WA, USA.
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Thangaraj S, Sun J. Ocean warming and acidification affect the transitional C:N:P ratio and macromolecular accumulation in the harmful raphidophyte Heterosigma akashiwo. Commun Biol 2023; 6:151. [PMID: 36747020 PMCID: PMC9902392 DOI: 10.1038/s42003-023-04524-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2022] [Accepted: 01/24/2023] [Indexed: 02/08/2023] Open
Abstract
Despite an increase in ocean warming and acidification that is expected to increase the number of harmful algal species worldwide, the population of the raphidophyte Heterosigma akashiwo has been reported to be reduced. However, how this species physically and metabolically modifies transitional C:N:P ratio and macromolecule accumulation is unknown. Considering 1st, 10th, and 20th culture generations under present (low-temperature; low-carbon-dioxide [LTLC] 21 °C; pCO2 400 ppm) and future (high-temperature; high-carbon-dioxide [HTHC] 25 °C; pCO2 1000 ppm) ocean conditions, we examined transitional C:N:P ratio and macromolecule level changes and performed transcriptome sequencing. The results showed that compared to 1st generation cells, 20th generation cells under HTHC conditions showed a large decrease in carbon quota (QC: 34%), nitrogen quota (QN: 36%), and phosphorus quota (QP: 32%), which were reflected in an overall reduction in DNA and RNA quantity. Decreased activation of photosynthetic, carbon fixation and lipid metabolic pathways coincided with changes in photosynthetic efficiency, carbon concentration, and lipid accumulation after long-term (20th generation) exposure to HTHC conditions. We observed that these variations in internal metabolic pathways were caused by external changes in temperature, which activated the (Ca+) signaling pathway, and external changes in pCO2, which altered proton exchange pathways. Our results suggest that H. akashiwo in a temperate environment will undergo profound changes in C:N:P ratio and macromolecular properties, leading to programmed cell death, in the future.
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Affiliation(s)
- Satheeswaran Thangaraj
- Institute for Advanced Marine Research, China University of Geosciences, Guangzhou, China
- State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Wuhan, China
- Department of Marine Science, Incheon National University, Incheon, South Korea
- Department of Physiology, Saveetha Dental College and Hospital, Saveetha Institute of Medical and Technical Sciences, Saveetha University, Chennai, India
| | - Jun Sun
- Institute for Advanced Marine Research, China University of Geosciences, Guangzhou, China.
- State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Wuhan, China.
- Research Centre for Indian Ocean Ecosystem, Tianjin University of Science and Technology, Tianjin, China.
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Xu D, Li C, Utz A, Weidenbacher PAB, Tang S, Sanyal M, Pulendran B, Kim PS. Designing epitope-focused vaccines via antigen reorientation. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2022. [PMID: 36597536 DOI: 10.1101/2022.09.08.507187] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
Abstract
UNLABELLED A major challenge in vaccine development, especially against rapidly evolving viruses, is the ability to focus the immune response toward evolutionarily conserved antigenic regions to confer broad protection. For example, while many broadly neutralizing antibodies against influenza have been found to target the highly conserved stem region of hemagglutinin (HA-stem), the immune response to seasonal influenza vaccines is predominantly directed to the immunodominant but variable head region (HA-head), leading to narrow-spectrum efficacy. Here, we first introduce an approach to controlling antigen orientation based on the site-specific insertion of short stretches of aspartate residues (oligoD) that facilitates antigen-binding to alum adjuvants. We demonstrate the generalizability of this approach to antigens from the Ebola virus, SARS-CoV-2, and influenza and observe enhanced antibody responses following immunization in all cases. Next, we use this approach to reorient HA in an "upside down" configuration, which we envision increases HA-stem exposure, therefore also improving its immunogenicity compared to HA-head. When applied to HA of H2N2 A/Japan/305/1957, the reoriented H2 HA (reoH2HA) on alum induced a stem-directed antibody response that cross-reacted with both group 1 and 2 influenza A HAs. Our results demonstrate the possibility and benefits of antigen reorientation via oligoD insertion, which represents a generalizable immunofocusing approach readily applicable for designing epitope-focused vaccine candidates. GRAPHICAL ABSTRACT Seasonal influenza vaccines induce a biased antibody response against the variable head of hemagglutinin, whereas conserved epitopes on the stem are a target for universal vaccines. Here we show that reorienting HA in an "upside-down" configuration sterically occludes the head and redirects the antibody response to the more exposed stem, thereby inducing broad cross-reactivity against hemagglutinins from diverse influenza strains.
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Biswas H. A story of resilience: Arctic diatom Chaetoceros gelidus exhibited high physiological plasticity to changing CO 2 and light levels. FRONTIERS IN PLANT SCIENCE 2022; 13:1028544. [PMID: 36438134 PMCID: PMC9692007 DOI: 10.3389/fpls.2022.1028544] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/26/2022] [Accepted: 10/26/2022] [Indexed: 06/16/2023]
Abstract
Arctic phytoplankton are experiencing multifaceted stresses due to climate warming, ocean acidification, retreating sea ice, and associated changes in light availability, and that may have large ecological consequences. Multiple stressor studies on Arctic phytoplankton, particularly on the bloom-forming species, may help understand their fitness in response to future climate change, however, such studies are scarce. In the present study, a laboratory experiment was conducted on the bloom-forming Arctic diatom Chaetoceros gelidus (earlier C. socialis) under variable CO2 (240 and 900 µatm) and light (50 and 100 µmol photons m-2 s-1) levels. The growth response was documented using the pre-acclimatized culture at 2°C in a closed batch system over 12 days until the dissolved inorganic nitrogen was depleted. Particulate organic carbon and nitrogen (POC and PON), pigments, cell density, and the maximum quantum yield of photosystem II (Fv/Fm) were measured on day 4 (D4), 6 (D6), 10 (D10), and 12 (D12). The overall growth response suggested that C. gelidus maintained a steady-state carboxylation rate with subsequent conversion to macromolecules as reflected in the per-cell POC contents under variable CO2 and light levels. A substantial amount of POC buildup at the low CO2 level (comparable to the high CO2 treatment) indicated the possibility of existing carbon dioxide concentration mechanisms (CCMs) that needs further investigation. Pigment signatures revealed a high level of adaptability to variable irradiance in this species without any major CO2 effect. PON contents per cell increased initially but decreased irrespective of CO2 levels when nitrogen was limited (D6 onward) possibly to recycle intracellular nitrogen resources resulting in enhanced C: N ratios. On D12 the decreased dissolved organic nitrogen levels could be attributed to consumption under nitrogen starvation. Such physiological plasticity could make C. gelidus "ecologically resilient" in the future Arctic.
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Affiliation(s)
- Haimanti Biswas
- National Institute of Oceanography - CSIR (Council of Scientific and Industrial Research), Biological Oceanography Division, Goa, India
- Polar Biological Oceanography, Alfred Wegener Institute of Polar and Marine Research, Bremerhaven, Germany
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Lacour T, Larivière J, Ferland J, Morin PI, Grondin PL, Donaher N, Cockshutt A, Campbell DA, Babin M. Photoacclimation of the polar diatom Chaetoceros neogracilis at low temperature. PLoS One 2022; 17:e0272822. [PMID: 36125987 PMCID: PMC9488821 DOI: 10.1371/journal.pone.0272822] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2022] [Accepted: 07/26/2022] [Indexed: 11/18/2022] Open
Abstract
Polar microalgae face two major challenges: 1- growing at temperatures (-1.7 to 5°C) that limit enzyme kinetics; and 2- surviving and exploiting a wide range of irradiance. The objective of this study is to understand the adaptation of an Arctic diatom to its environment by studying its ability to acclimate to changes in light and temperature. We acclimated the polar diatom Chaetoceros neogracilis to various light levels at two different temperatures and studied its growth and photosynthetic properties using semi-continuous cultures. Rubisco content was high, to compensate for low catalytic rates, but did not change detectably with growth temperature. Contrary to what is observed in temperate species, in C. neogracilis, carbon fixation rate (20 min 14C incorporation) equaled net growth rate (μ) suggesting very low or very rapid (<20 min) re-oxidation of the newly fixed carbon. The comparison of saturation irradiances for electron transport, oxygen net production and carbon fixation revealed alternative electron pathways that could provide energy and reducing power to the cell without consuming organic carbon which is a very limiting product at low temperatures. High protein contents, low re-oxidation of newly fixed carbon and the use of electron pathways alternative to carbon fixation may be important characteristics allowing efficient growth under those extreme environmental conditions.
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Affiliation(s)
- Thomas Lacour
- Ifremer, PHYTOX, PHYSALG, Brest, France
- Département de Biologie, Takuvik International Research Laboratory (IRL-3376, CNRS (France) & ULaval (Canada), Université Laval, Québec, Canada
| | - Jade Larivière
- Département de Biologie, Takuvik International Research Laboratory (IRL-3376, CNRS (France) & ULaval (Canada), Université Laval, Québec, Canada
| | - Joannie Ferland
- Département de Biologie, Takuvik International Research Laboratory (IRL-3376, CNRS (France) & ULaval (Canada), Université Laval, Québec, Canada
| | - Philippe-Israël Morin
- Département de Biologie, Takuvik International Research Laboratory (IRL-3376, CNRS (France) & ULaval (Canada), Université Laval, Québec, Canada
| | - Pierre-Luc Grondin
- Département de Biologie, Takuvik International Research Laboratory (IRL-3376, CNRS (France) & ULaval (Canada), Université Laval, Québec, Canada
| | - Natalie Donaher
- Department of Chemistry and Biochemistry, Mount Allison University, Sackville, Canada
| | - Amanda Cockshutt
- Department of Chemistry and Biochemistry, Mount Allison University, Sackville, Canada
| | - Douglas A. Campbell
- Department of Chemistry and Biochemistry, Mount Allison University, Sackville, Canada
| | - Marcel Babin
- Département de Biologie, Takuvik International Research Laboratory (IRL-3376, CNRS (France) & ULaval (Canada), Université Laval, Québec, Canada
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Xu D, Tong S, Wang B, Zhang X, Wang W, Zhang X, Fan X, Wang Y, Sun K, Ye N. Ocean acidification stimulation of phytoplankton growth depends on the extent of departure from the optimal growth temperature. MARINE POLLUTION BULLETIN 2022; 177:113510. [PMID: 35299145 DOI: 10.1016/j.marpolbul.2022.113510] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/04/2021] [Revised: 01/23/2022] [Accepted: 02/25/2022] [Indexed: 06/14/2023]
Abstract
Ocean acidification and warming are two major environmental stressors; however, the generality of how warming will alter growth responses of phytoplankton to ocean acidification is less known. Here, enhancement of growth by high CO2 (HC) in Phaeodactylum tricornutum and Thalassiosira weissflogii was most prominent at optimum temperature. The extent to which growth rates in HC cultures were raised compared to low CO2 (LC) cultures tended to decrease with increasing or decreasing temperature, compared to the optimum. Further mechanistic studies in P. tricornutum revealed that cellular carbon and nitrogen content, superoxide dismutase activity, and respiration were generally higher in HC than those in LC at high and low temperatures, whereas PSII photochemical parameters were generally lower in HC than in LC at high and low temperatures. These results indicate that HC-grown cells needed to invest more energy and materials to maintain intracellular homeostasis and repair damage induced by the unsuitable temperatures.
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Affiliation(s)
- Dong Xu
- Yellow Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Qingdao, China; Function Laboratory for Marine Fisheries Science and Food Production Processes, Qingdao National Laboratory for Marine Science and Technology, Qingdao, China
| | - Shanying Tong
- College of Life Science, Ludong University, Yantai, China
| | - Bingkun Wang
- School of Environment, Harbin Institute of Technology, Harbin, China
| | - Xiansheng Zhang
- Yellow Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Qingdao, China
| | - Wei Wang
- Yellow Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Qingdao, China
| | - Xiaowen Zhang
- Yellow Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Qingdao, China
| | - Xiao Fan
- Yellow Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Qingdao, China
| | - Yitao Wang
- Yellow Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Qingdao, China
| | - Ke Sun
- Yellow Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Qingdao, China
| | - Naihao Ye
- Yellow Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Qingdao, China; Function Laboratory for Marine Fisheries Science and Food Production Processes, Qingdao National Laboratory for Marine Science and Technology, Qingdao, China.
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Hudson-Heck E, Liu X, Byrne RH. Purification and Physical-Chemical Characterization of Bromocresol Purple for Carbon System Measurements in Freshwaters, Estuaries, and Oceans. ACS OMEGA 2021; 6:17941-17951. [PMID: 34308029 PMCID: PMC8296007 DOI: 10.1021/acsomega.1c01579] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/24/2021] [Accepted: 06/23/2021] [Indexed: 06/13/2023]
Abstract
This work provides an algorithm to describe the salinity (S P) and temperature (T) dependence of the equilibrium and molar absorptivity characteristics of purified bromocresol purple (BCP, a pH indicator) over a river-to-sea range of salinity (0 ≤ S P ≤ 40). Based on the data obtained in this study, the pH of water samples can be calculated on the seawater pH scale as follows: pHSW = -log(K 2 e 2) + log((R - e 1)/(1 - Re 4)) where -log(K 2 e 2) = 4.981 - 0.1710S P 0.5 + 0.09428S P + 0.3794S P 1.5 + 0.0009129S P 2 + 310.2/T - 17.33S 1.5/T - 0.05895S P 1.5 ln T - 0.0005730S P 0.5 T, e 1 = 0.00049 ± 0.00029, and e 4 = -7.101 × 10-3 + 7.674 × 10-5 T + 1.361 × 10-5 S P. The term pHSW is the negative log of the hydrogen ion concentration determined on the seawater pH scale; R is the ratio of BCP absorbances (A) at 432 and 589 nm; K 2 is the equilibrium constant for the second BCP dissociation step; and e 1, e 2, and e 4 are BCP molar absorptivity ratios. A log(K 2 e 2) equation is also presented on the total pH scale. The e 4 value determined for purified BCP in this study can be used with previously published procedures to correct BCP absorbance measurements obtained using off-the-shelf (unpurified) BCP. This work provides a method for purifying BCP, fills a critical gap in the suite of available purified sulfonephthalein indicators, enables high-quality spectrophotometric measurements of total alkalinity, and facilitates pH measurements in freshwater, estuarine, and ocean environments within the range 4.0 ≤ pH ≤ 7.5.
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The Role of Extracellular Carbonic Anhydrase in Biogeochemical Cycling: Recent Advances and Climate Change Responses. Int J Mol Sci 2021; 22:ijms22147413. [PMID: 34299033 PMCID: PMC8307829 DOI: 10.3390/ijms22147413] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2021] [Revised: 07/06/2021] [Accepted: 07/07/2021] [Indexed: 12/14/2022] Open
Abstract
Climate change has been predicted to influence the marine phytoplankton community and its carbon acquisition strategy. Extracellular carbonic anhydrase (eCA) is a zinc metalloenzyme that catalyses the relatively slow interconversion between HCO3− and CO2. Early results indicated that sub-nanomolar levels of eCA at the sea surface were sufficient to enhance the oceanic uptake rate of CO2 on a global scale by 15%, an addition of 0.37 Pg C year−1. Despite its central role in the marine carbon cycle, only in recent years have new analytical techniques allowed the first quantifications of eCA and its activity in the oceans. This opens up new research areas in the field of marine biogeochemistry and climate change. Light and suitable pH conditions, as well as growth stage, are crucial factors in eCA expression. Previous studies showed that phytoplankton eCA activity and concentrations are affected by environmental stressors such as ocean acidification and UV radiation as well as changing light conditions. For this reason, eCA is suggested as a biochemical indicator in biomonitoring programmes and could be used for future response prediction studies in changing oceans. This review aims to identify the current knowledge and gaps where new research efforts should be focused to better determine the potential feedback of phytoplankton via eCA in the marine carbon cycle in changing oceans.
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Opposite Growth Responses of Alexandrium minutum and Alexandrium catenella to Photoperiods and Temperatures. PLANTS 2021; 10:plants10061056. [PMID: 34070469 PMCID: PMC8229041 DOI: 10.3390/plants10061056] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/02/2021] [Revised: 05/11/2021] [Accepted: 05/20/2021] [Indexed: 12/01/2022]
Abstract
Shift of phytoplankton niches from low to high latitudes has altered their experienced light exposure durations and temperatures. To explore this interactive effect, the growth, physiology, and cell compositions of smaller Alexandrium minutum and larger A. catenella, globally distributed toxic red tide dinoflagellates, were studied under a matrix of photoperiods (light:dark cycles of 8:16, 16:8, and 24:0) and temperatures (18 °C, 22 °C, 25 °C, and 28 °C). Under continuous growth light condition (L:D 24:0), the growth rate (µ) of small A. minutum increased from low to medium temperature, then decreased to high temperature, while the µ of large A. catenella continuously decreased with increasing temperatures. Shortened photoperiods reduced the µ of A. minutum, but enhanced that of A. catenella. As temperature increased, cellular Chl a content increased in both A. minutum and A. catenella, while the temperature-induced effect on RubisCO content was limited. Shortened photoperiods enhanced the Chl a but reduced RubisCO contents across temperatures. Moreover, shortened photoperiods enhanced photosynthetic capacities of both A. minutum and A. catenella, i.e., promoting the PSII photochemical quantum yield (FV/FM, ΦPSII), saturation irradiance (EK), and maximum relative electron transfer rate (rETRmax). Shortened photoperiods also enhanced dark respiration of A. minutum across temperatures, but reduced that of A. catenella, as well as the antioxidant activities of both species. Overall, A. minutum and A. catenella showed differential growth responses to photoperiods across temperatures, probably with cell size.
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Ma J, Wang P. Effects of rising atmospheric CO 2 levels on physiological response of cyanobacteria and cyanobacterial bloom development: A review. THE SCIENCE OF THE TOTAL ENVIRONMENT 2021; 754:141889. [PMID: 32920383 DOI: 10.1016/j.scitotenv.2020.141889] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/26/2020] [Revised: 07/15/2020] [Accepted: 08/20/2020] [Indexed: 05/19/2023]
Abstract
Increasing atmospheric CO2 concentration negatively impacts aquatic ecosystems and may exacerbate the problem of undesirable cyanobacterial bloom development in freshwater ecosystems. Elevated levels of atmospheric CO2 may increase the levels of dissolved CO2 in freshwater systems, via air-water exchanges, enhancing primary production in the water and catchments. Although high CO2 levels improve cyanobacterial growth and increase cyanobacterial biomass, the impacts on their internal physiological processes can be more complex. Here, we have reviewed previous studies to evaluate the physiological responses of cyanobacteria to high concentrations of CO2. In response to high CO2 concentrations, the pressures of inorganic carbon absorption are reduced, and carbon concentration mechanisms are downregulated, affecting the intracellular metabolic processes and competitiveness of the cyanobacteria. Nitrogen and phosphorus metabolism and light utilization are closely related to CO2 assimilation, and these processes are likely to be affected by resource and energy reallocation when CO2 levels are high. Additionally, the responses of diazotrophic and toxic cyanobacteria to elevated CO2 levels were specifically reviewed. The responses of diazotrophic cyanobacteria to elevated CO2 concentrations were found to be inconsistent, probably because of differences in other factors in experimental designs. Toxic cyanobacteria tended to be superior to non-toxic strains at low levels of CO2; however, the specific effects of microcystin on the regulation require further investigation. Furthermore, the effects of increasing CO2 levels on cyanobacterial competitiveness in phytoplankton communities and nutrient cycling in aquatic ecosystems were reviewed. High CO2 concentrations may make cyanobacteria less competitive relative to other algal taxa; however, due to the complexity of natural systems and the specificity of algal species, the dominant positions of the cyanobacteria do not seems to be changed. To better understand cyanobacterial responses to elevated CO2 levels and help control cyanobacterial bloom developments, this review has identified key areas for future research.
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Affiliation(s)
- Jingjie Ma
- Key Laboratory of Integrated Regulation and Resources Development on Shallow Lakes, Ministry of Education, Hohai University, Nanjing 210098, People's Republic of China; College of Environment, Hohai University, Nanjing 210098, People's Republic of China
| | - Peifang Wang
- Key Laboratory of Integrated Regulation and Resources Development on Shallow Lakes, Ministry of Education, Hohai University, Nanjing 210098, People's Republic of China; College of Environment, Hohai University, Nanjing 210098, People's Republic of China.
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14
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Pierangelini M, Thiry M, Cardol P. Different levels of energetic coupling between photosynthesis and respiration do not determine the occurrence of adaptive responses of Symbiodiniaceae to global warming. THE NEW PHYTOLOGIST 2020; 228:855-868. [PMID: 32535971 PMCID: PMC7590187 DOI: 10.1111/nph.16738] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/14/2020] [Accepted: 05/30/2020] [Indexed: 05/06/2023]
Abstract
Disentangling the metabolic functioning of corals' endosymbionts (Symbiodiniaceae) is relevant to understanding the response of coral reefs to warming oceans. In this work, we first question whether there is an energetic coupling between photosynthesis and respiration in Symbiodiniaceae (Symbiodinium, Durusdinium and Effrenium), and second, how different levels of energetic coupling will affect their adaptive responses to global warming. Coupling between photosynthesis and respiration was established by determining the variation of metabolic rates during thermal response curves, and how inhibition of respiration affects photosynthesis. Adaptive (irreversible) responses were studied by exposing two Symbiodinium species with different levels of photosynthesis-respiration interaction to high temperature conditions (32°C) for 1 yr. We found that some Symbiodiniaceae have a high level of energetic coupling; that is, photosynthesis and respiration have the same temperature dependency, and photosynthesis is negatively affected when respiration is inhibited. Conversely, photosynthesis and respiration are not coupled in other species. In any case, prolonged exposure to high temperature caused adjustments in both photosynthesis and respiration, but these changes were fully reversible. We conclude that energetic coupling between photosynthesis and respiration exhibits wide variation amongst Symbiodiniaceae and does not determine the occurrence of adaptive responses in Symbiodiniaceae to temperature increase.
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Affiliation(s)
- Mattia Pierangelini
- Génétique et Physiologie des MicroalguesInBioS/PhytosystemsInstitut de BotaniqueUniversité de LiègeB22Liège4000Belgium
| | - Marc Thiry
- Unit of Cell BiologyGIGA‐NeurosciencesCHU Sart‐TilmanUniversity of LiègeLiègeB36, 4000Belgium
| | - Pierre Cardol
- Génétique et Physiologie des MicroalguesInBioS/PhytosystemsInstitut de BotaniqueUniversité de LiègeB22Liège4000Belgium
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15
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Young JN, Schmidt K. It's what's inside that matters: physiological adaptations of high-latitude marine microalgae to environmental change. THE NEW PHYTOLOGIST 2020; 227:1307-1318. [PMID: 32391569 DOI: 10.1111/nph.16648] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/23/2019] [Accepted: 03/23/2020] [Indexed: 05/13/2023]
Abstract
Marine microalgae within seawater and sea ice fuel high-latitude ecosystems and drive biogeochemical cycles through the fixation and export of carbon, uptake of nutrients, and production and release of oxygen and organic compounds. High-latitude marine environments are characterized by cold temperatures, dark winters and a strong seasonal cycle. Within this environment a number of diverse and dynamic habitats exist, particularly in association with the formation and melt of sea ice, with distinct microalgal communities that transition with the season. Algal physiology is a crucial component, both responding to the dynamic environment and in turn influencing its immediate physicochemical environment. As high-latitude oceans shift into new climate regimes the analysis of seasonal responses may provide insights into how microalgae will respond to long-term environmental change. This review discusses recent developments in our understanding of how the physiology of high-latitude marine microalgae is regulated over a polar seasonal cycle, with a focus on ice-associated (sympagic) algae. In particular, physiologies that impact larger scale processes will be explored, with an aim to improve our understanding of current and future ecosystems and biogeochemical cycles.
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Affiliation(s)
- Jodi N Young
- School of Oceanography, University of Washington, Seattle, WA, 98195, USA
| | - Katrin Schmidt
- School of Oceanography, University of Washington, Seattle, WA, 98195, USA
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Iñiguez C, Capó-Bauçà S, Niinemets Ü, Stoll H, Aguiló-Nicolau P, Galmés J. Evolutionary trends in RuBisCO kinetics and their co-evolution with CO 2 concentrating mechanisms. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2020; 101:897-918. [PMID: 31820505 DOI: 10.1111/tpj.14643] [Citation(s) in RCA: 65] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/17/2019] [Revised: 11/15/2019] [Accepted: 11/27/2019] [Indexed: 05/19/2023]
Abstract
RuBisCO-catalyzed CO2 fixation is the main source of organic carbon in the biosphere. This enzyme is present in all domains of life in different forms (III, II, and I) and its origin goes back to 3500 Mya, when the atmosphere was anoxygenic. However, the RuBisCO active site also catalyzes oxygenation of ribulose 1,5-bisphosphate, therefore, the development of oxygenic photosynthesis and the subsequent oxygen-rich atmosphere promoted the appearance of CO2 concentrating mechanisms (CCMs) and/or the evolution of a more CO2 -specific RuBisCO enzyme. The wide variability in RuBisCO kinetic traits of extant organisms reveals a history of adaptation to the prevailing CO2 /O2 concentrations and the thermal environment throughout evolution. Notable differences in the kinetic parameters are found among the different forms of RuBisCO, but the differences are also associated with the presence and type of CCMs within each form, indicative of co-evolution of RuBisCO and CCMs. Trade-offs between RuBisCO kinetic traits vary among the RuBisCO forms and also among phylogenetic groups within the same form. These results suggest that different biochemical and structural constraints have operated on each type of RuBisCO during evolution, probably reflecting different environmental selective pressures. In a similar way, variations in carbon isotopic fractionation of the enzyme point to significant differences in its relationship to the CO2 specificity among different RuBisCO forms. A deeper knowledge of the natural variability of RuBisCO catalytic traits and the chemical mechanism of RuBisCO carboxylation and oxygenation reactions raises the possibility of finding unrevealed landscapes in RuBisCO evolution.
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Affiliation(s)
- Concepción Iñiguez
- Research Group on Plant Biology under Mediterranean Conditions, Universitat de les Illes Balears-INAGEA, Palma, Balearic Islands, Spain
| | - Sebastià Capó-Bauçà
- Research Group on Plant Biology under Mediterranean Conditions, Universitat de les Illes Balears-INAGEA, Palma, Balearic Islands, Spain
| | - Ülo Niinemets
- Chair of Crop Science and Plant Biology, Institute of Agricultural and Environmental Sciences, Estonian University of Life Sciences, Kreutzwaldi 1, 51006, Tartu, Estonia
- Estonian Academy of Sciences, Kohtu 6, 10130, Tallinn, Estonia
| | - Heather Stoll
- Department of Earth Sciences, ETH Zürich, Sonnegstrasse 5, 8092, Zürich, Switzerland
| | - Pere Aguiló-Nicolau
- Research Group on Plant Biology under Mediterranean Conditions, Universitat de les Illes Balears-INAGEA, Palma, Balearic Islands, Spain
| | - Jeroni Galmés
- Research Group on Plant Biology under Mediterranean Conditions, Universitat de les Illes Balears-INAGEA, Palma, Balearic Islands, Spain
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17
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Bozzato D, Jakob T, Wilhelm C. Effects of temperature and salinity on respiratory losses and the ratio of photosynthesis to respiration in representative Antarctic phytoplankton species. PLoS One 2019; 14:e0224101. [PMID: 31634379 PMCID: PMC6802872 DOI: 10.1371/journal.pone.0224101] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2019] [Accepted: 10/05/2019] [Indexed: 11/18/2022] Open
Abstract
The Southern Ocean (SO) is a net sink for atmospheric CO2 whereby the photosynthetic activity of phytoplankton and sequestration of organic carbon (biological pump) plays an important role. Global climate change will tremendously influence the dynamics of environmental conditions for the phytoplankton community, and the phytoplankton will have to acclimate to a combination of changes of e.g. water temperature, salinity, pH, and nutrient supply. The efficiency of the biological pump is not only determined by the photosynthetic activity but also by the extent of respiratory carbon losses of phytoplankton cells. Thus, the present study investigated the effect of different temperature and salinity combinations on the ratio of gross photosynthesis to respiration (rGP/R) in two representative phytoplankton species of the SO. In the comparison of phytoplankton grown at 1 and 4°C the rGP/R decreased from 11.5 to 7.7 in Chaetoceros sp., from 9.1 to 3.2 in Phaeocystis antarctica strain 109, and from 12.4 to 7.0 in P. antarctica strain 764, respectively. The decrease of rGP/R was primarily dependent on temperature whereas salinity was only of minor importance. Moreover, the different rGP/R at 1 and 4°C were caused by changes of temperature-dependent respiration rates but were independent of changes of photosynthetic rates. For further interpretation, net primary production (NPP) was calculated for different seasonal conditions in the SO with specific combinations of irradiance, temperature, and salinity. Whereas, maximum photosynthetic rates significantly correlated with calculated NPP under experimental ‘Spring’, ‘Summer’, and ‘Autumn’ conditions, there was no correlation between rGP/R and the respective values of NPP. The study revealed species-specific differences in the acclimation to temperature and salinity changes that could be linked to their different original habitats.
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Affiliation(s)
- Deborah Bozzato
- University Leipzig, Institute of Biology, Plant Physiology, Leipzig, Germany
| | - Torsten Jakob
- University Leipzig, Institute of Biology, Plant Physiology, Leipzig, Germany
- * E-mail:
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18
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Zhang H, He YB, Wu PF, Zhang SF, Xie ZX, Li DX, Lin L, Chen F, Wang DZ. Functional Differences in the Blooming Phytoplankton Heterosigma akashiwo and Prorocentrum donghaiense Revealed by Comparative Metaproteomics. Appl Environ Microbiol 2019; 85:e01425-19. [PMID: 31375486 PMCID: PMC6752027 DOI: 10.1128/aem.01425-19] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2019] [Accepted: 07/07/2019] [Indexed: 12/21/2022] Open
Abstract
Phytoplankton blooms are natural phenomena in the ocean, which are the results of rapid cell growth of some phytoplankton species in a unique environment. However, little is known about the molecular events occurring during the bloom. Here, we compared metaproteomes of two phytoplankton Heterosigma akashiwo and Prorocentrum donghaiense in the coastal East China Sea. H. akashiwo and P. donghaiense accounted for 7.82% and 4.74% of the phytoplankton community protein abundances in the nonbloom sample, whereas they contributed to 60.13% and 78.09%, respectively, in their individual blooming samples. Compared with P. donghaiense, H. akashiwo possessed a significantly higher abundance of light-harvesting complex proteins, carbonic anhydrasem and RuBisCO. The blooming H. akashiwo cells expressed more proteins related to external nutrient acquisition, such as bicarbonate transporter SLC4, ammonium transporter, nitrite transporter, and alkaline phosphatase, while the blooming P. donghaiense cells highly expressed proteins related to extra- and intracellular organic nutrient utilization, such as amino acid transporter, 5'-nucleotidase, acid phosphatase, and tripeptidyl-peptidase. The strong capabilities of light harvesting, as well as acquisition and assimilation of inorganic carbon, nitrogen, and phosphorus, facilitated the formation of the H. akashiwo bloom under the high turbidity and inorganic nutrient-sufficient condition, whereas the competitive advantages in organic nutrient acquisition and reallocation guaranteed the occurrence of the P. donghaiense bloom under the inorganic nutrient-insufficient condition. This study highlights the power of metaproteomics for revealing the underlying molecular behaviors of different coexisting phytoplankton species and advances our knowledge on the formation of phytoplankton blooms.IMPORTANCE A deep understanding of the mechanisms driving bloom formation is a prerequisite for effective bloom management. Metaproteomics was applied in this study to reveal the adaptive and responsive strategies of two coexisting phytoplankton species, H. akashiwo and P. donghaiense, during their bloom periods. Metabolic features and niche divergence in light harvesting, as well as carbon, nitrogen, and phosphorus acquisition and assimilation likely promoted the bloom occurrence under different environments. The molecular behaviors of coexisting bloom-causing species will give clues for bloom monitoring and management in the oceans.
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Affiliation(s)
- Hao Zhang
- State Key Laboratory of Marine Environmental Science/College of the Environment and Ecology, Xiamen University, Xiamen, China
| | - Yan-Bin He
- BGI-Shenzhen, Shenzhen, Guangdong, China
| | - Peng-Fei Wu
- State Key Laboratory of Marine Environmental Science/College of the Environment and Ecology, Xiamen University, Xiamen, China
| | - Shu-Feng Zhang
- State Key Laboratory of Marine Environmental Science/College of the Environment and Ecology, Xiamen University, Xiamen, China
| | - Zhang-Xian Xie
- State Key Laboratory of Marine Environmental Science/College of the Environment and Ecology, Xiamen University, Xiamen, China
| | - Dong-Xu Li
- State Key Laboratory of Marine Environmental Science/College of the Environment and Ecology, Xiamen University, Xiamen, China
| | - Lin Lin
- State Key Laboratory of Marine Environmental Science/College of the Environment and Ecology, Xiamen University, Xiamen, China
| | - Feng Chen
- Institute of Marine and Environmental Technology, University of Maryland Center for Environmental Science, Baltimore, Maryland, USA
| | - Da-Zhi Wang
- State Key Laboratory of Marine Environmental Science/College of the Environment and Ecology, Xiamen University, Xiamen, China
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19
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Beszteri S, Thoms S, Benes V, Harms L, Trimborn S. The Response of Three Southern Ocean Phytoplankton Species to Ocean Acidification and Light Availability: A Transcriptomic Study. Protist 2018; 169:958-975. [DOI: 10.1016/j.protis.2018.08.003] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2018] [Revised: 08/06/2018] [Accepted: 08/17/2018] [Indexed: 01/16/2023]
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20
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Heiden JP, Thoms S, Bischof K, Trimborn S, Raven J. Ocean acidification stimulates particulate organic carbon accumulation in two Antarctic diatom species under moderate and high natural solar radiation. JOURNAL OF PHYCOLOGY 2018; 54:505-517. [PMID: 29791031 PMCID: PMC6120492 DOI: 10.1111/jpy.12753] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/07/2017] [Accepted: 04/24/2018] [Indexed: 06/08/2023]
Abstract
Impacts of rising atmospheric CO2 concentrations and increased daily irradiances from enhanced surface water stratification on phytoplankton physiology in the coastal Southern Ocean remain still unclear. Therefore, in the two Antarctic diatoms Fragilariopsis curta and Odontella weissflogii, the effects of moderate and high natural solar radiation combined with either ambient or future pCO2 on cellular particulate organic carbon (POC) contents and photophysiology were investigated. Results showed that increasing CO2 concentrations had greater impacts on diatom physiology than exposure to increasing solar radiation. Irrespective of the applied solar radiation regime, cellular POC quotas increased with future pCO2 in both diatoms. Lowered maximum quantum yields of photochemistry in PSII (Fv /Fm ) indicated a higher photosensitivity under these conditions, being counteracted by increased cellular concentrations of functional photosynthetic reaction centers. Overall, our results suggest that both bloom-forming Antarctic coastal diatoms might increase carbon contents under future pCO2 conditions despite reduced physiological fitness. This indicates a higher potential for primary productivity by the two diatom species with important implications for the CO2 sequestration potential of diatom communities in the future coastal Southern Ocean.
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Affiliation(s)
- Jasmin P. Heiden
- Alfred Wegener Institute Helmholtz Center for Polar and Marine ResearchAm Handelshafen 1227570BremerhavenGermany
- Marine BotanyUniversity BremenLeobener Str. NW228359BremenGermany
| | - Silke Thoms
- Alfred Wegener Institute Helmholtz Center for Polar and Marine ResearchAm Handelshafen 1227568BremerhavenGermany
| | - Kai Bischof
- Marine BotanyUniversity BremenLeobener Str. NW228359BremenGermany
| | - Scarlett Trimborn
- Alfred Wegener Institute Helmholtz Center for Polar and Marine ResearchAm Handelshafen 1227570BremerhavenGermany
- Marine BotanyUniversity BremenLeobener Str. NW228359BremenGermany
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21
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Da Silva R, Mazumdar A, Mapder T, Peketi A, Joshi RK, Shaji A, Mahalakshmi P, Sawant B, Naik BG, Carvalho MA, Molletti SK. Salinity stratification controlled productivity variation over 300 ky in the Bay of Bengal. Sci Rep 2017; 7:14439. [PMID: 29089526 PMCID: PMC5663938 DOI: 10.1038/s41598-017-14781-3] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2017] [Accepted: 10/16/2017] [Indexed: 11/12/2022] Open
Abstract
The unique hydrographic setting of the Bay of Bengal (BoB) makes it an ideal tropical marine system to study the influence of regional and global forcings on productivity and [CO2aq] through the late quaternary. Enormous fresh water flux into the BoB and consequent salinity stratification significantly weaken the convective mixing and wind driven processes which are commonly responsible for transport of nutrients to the euphotic zone driving primary productivity. Here we present a high resolution organic carbon-CaCO3 MAR and δ13CTOC records for the last 300 ky from the BoB. The results show significant productivity variation at marine isotope sub-stages and millennial timescales. Colder sub-stages and stadials (Dansgard-Oeschger cycle) show a boost in productivity which may be attributed to thinning of low salinity cap, thereby facilitating efficient nutrient transport across the euphotic zone by the combination of wind driven processes (entrainment and upwelling), convective mixing and cold core eddies. The [CO2aq] was a net result of global pCO2 variation and regional processes. Our long term high-resolution data indicates a possibility of marked change in productivity/biogeochemistry of BOB in the future due to global warming, thus affecting the coastal economy.
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Affiliation(s)
- R Da Silva
- CSIR, National Institute of Oceanography, Donapaula, Goa, 403004, India
| | - A Mazumdar
- CSIR, National Institute of Oceanography, Donapaula, Goa, 403004, India.
| | - T Mapder
- ACEMS, Queensland University of Technology, Brisbane, QLD4000, Australia
| | - A Peketi
- CSIR, National Institute of Oceanography, Donapaula, Goa, 403004, India
| | - R K Joshi
- Geological Survey of India, Salt lake, Kolkata, 700091, India
| | - A Shaji
- Centre for Marine Living Resources & Ecology, Kochi, 682037, Kerala, India
| | - P Mahalakshmi
- Flat No. CS-1, Block-C, Astral Garden, Panaji, 403004, Goa, India
| | - B Sawant
- CSIR, National Institute of Oceanography, Donapaula, Goa, 403004, India
| | - B G Naik
- CSIR, National Institute of Oceanography, Donapaula, Goa, 403004, India
| | - M A Carvalho
- CSIR, National Institute of Oceanography, Donapaula, Goa, 403004, India
| | - S K Molletti
- Delta Studies Institute, Andhra University, Visakhapatnam, 530017, Andhra Pradesh, India
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22
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Hoppe CJM, Schuback N, Semeniuk D, Giesbrecht K, Mol J, Thomas H, Maldonado MT, Rost B, Varela DE, Tortell PD. Resistance of Arctic phytoplankton to ocean acidification and enhanced irradiance. Polar Biol 2017; 41:399-413. [PMID: 31983801 PMCID: PMC6952045 DOI: 10.1007/s00300-017-2186-0] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2017] [Revised: 07/21/2017] [Accepted: 07/23/2017] [Indexed: 11/29/2022]
Abstract
The Arctic Ocean is a region particularly prone to ongoing ocean acidification (OA) and climate-driven changes. The influence of these changes on Arctic phytoplankton assemblages, however, remains poorly understood. In order to understand how OA and enhanced irradiances (e.g., resulting from sea–ice retreat) will alter the species composition, primary production, and eco-physiology of Arctic phytoplankton, we conducted an incubation experiment with an assemblage from Baffin Bay (71°N, 68°W) under different carbonate chemistry and irradiance regimes. Seawater was collected from just below the deep Chl a maximum, and the resident phytoplankton were exposed to 380 and 1000 µatm pCO2 at both 15 and 35% incident irradiance. On-deck incubations, in which temperatures were 6 °C above in situ conditions, were monitored for phytoplankton growth, biomass stoichiometry, net primary production, photo-physiology, and taxonomic composition. During the 8-day experiment, taxonomic diversity decreased and the diatom Chaetoceros socialis became increasingly dominant irrespective of light or CO2 levels. We found no statistically significant effects from either higher CO2 or light on physiological properties of phytoplankton during the experiment. We did, however, observe an initial 2-day stress response in all treatments, and slight photo-physiological responses to higher CO2 and light during the first five days of the incubation. Our results thus indicate high resistance of Arctic phytoplankton to OA and enhanced irradiance levels, challenging the commonly predicted stimulatory effects of enhanced CO2 and light availability for primary production.
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Affiliation(s)
- C J M Hoppe
- 1Department of Earth, Ocean and Atmospheric Sciences, University of British Columbia, Vancouver, BC Canada.,2Marine Biogeosciences, Alfred Wegener Institute - Helmholtz Centre for Polar and Marine Research, Am Handelshafen 12, 27570 Bremerhaven, Germany
| | - N Schuback
- 1Department of Earth, Ocean and Atmospheric Sciences, University of British Columbia, Vancouver, BC Canada.,3Department of Physics and Astronomy, Curtin University, Perth, WA Australia
| | - D Semeniuk
- 1Department of Earth, Ocean and Atmospheric Sciences, University of British Columbia, Vancouver, BC Canada
| | - K Giesbrecht
- 4School of Earth and Ocean Sciences, University of Victoria, Victoria, BC Canada
| | - J Mol
- 5Department of Oceanography, Dalhousie University, Halifax, NS Canada
| | - H Thomas
- 5Department of Oceanography, Dalhousie University, Halifax, NS Canada
| | - M T Maldonado
- 1Department of Earth, Ocean and Atmospheric Sciences, University of British Columbia, Vancouver, BC Canada
| | - B Rost
- 2Marine Biogeosciences, Alfred Wegener Institute - Helmholtz Centre for Polar and Marine Research, Am Handelshafen 12, 27570 Bremerhaven, Germany
| | - D E Varela
- 4School of Earth and Ocean Sciences, University of Victoria, Victoria, BC Canada.,6Department of Biology, University of Victoria, Victoria, BC Canada
| | - P D Tortell
- 1Department of Earth, Ocean and Atmospheric Sciences, University of British Columbia, Vancouver, BC Canada.,7Department of Botany, University of British Columbia, Victoria, BC Canada.,8Peter Wall Institute for Advanced Studies, University of British Columbia, Vancouver, Canada
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23
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Young JN, Hopkinson BM. The potential for co-evolution of CO2-concentrating mechanisms and Rubisco in diatoms. JOURNAL OF EXPERIMENTAL BOTANY 2017; 68:3751-3762. [PMID: 28645158 DOI: 10.1093/jxb/erx130] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Diatoms are a diverse group of unicellular algae that contribute significantly to global photosynthetic carbon fixation and export in the modern ocean, and are an important source of microfossils for paleoclimate reconstructions. Because of their importance in the environment, diatoms have been a focus of study on the physiology and ecophysiology of carbon fixation, in particular their CO2-concentrating mechanisms (CCMs) and Rubisco characteristics. While carbon fixation in diatoms is not as well understood as in certain model aquatic photoautotrophs, a greater number of species have been examined in diatoms. Recent work has highlighted a large diversity in the function, physiology, and kinetics of both the CCM and Rubisco between different diatom species. This diversity was unexpected since it has generally been assumed that CCMs and Rubiscos were similar within major algal lineages as the result of selective events deep in evolutionary history, and suggests a more recent co-evolution between the CCM and Rubisco within diatoms. This review explores our current understanding of the diatom CCM and highlights the diversity of both the CCM and Rubisco kinetics. We will suggest possible environmental, physiological, and evolutionary drivers for the co-evolution of the CCM and Rubisco in diatoms.
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Affiliation(s)
- Jodi N Young
- University of Washington, School of Oceanography, Seattle, WA 98105, USA
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24
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Raven JA, Beardall J, Sánchez-Baracaldo P. The possible evolution and future of CO2-concentrating mechanisms. JOURNAL OF EXPERIMENTAL BOTANY 2017; 68:3701-3716. [PMID: 28505361 DOI: 10.1093/jxb/erx110] [Citation(s) in RCA: 64] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
CO2-concentrating mechanisms (CCMs), based either on active transport of inorganic carbon (biophysical CCMs) or on biochemistry involving supplementary carbon fixation into C4 acids (C4 and CAM), play a major role in global primary productivity. However, the ubiquitous CO2-fixing enzyme in autotrophs, Rubisco, evolved at a time when atmospheric CO2 levels were very much higher than today and O2 was very low and, as CO2 and O2 approached (by no means monotonically), today's levels, at some time subsequently many organisms evolved a CCM that increased the supply of CO2 and decreased Rubisco oxygenase activity. Given that CO2 levels and other environmental factors have altered considerably between when autotrophs evolved and the present day, and are predicted to continue to change into the future, we here examine the drivers for, and possible timing of, evolution of CCMs. CCMs probably evolved when CO2 fell to 2-16 times the present atmospheric level, depending on Rubisco kinetics. We also assess the effects of other key environmental factors such as temperature and nutrient levels on CCM activity and examine the evidence for evolutionary changes in CCM activity and related cellular processes as well as limitations on continuity of CCMs through environmental variations.
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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, UK
- Functional Plant Biology and Climate Change Cluster, University of Technology Sydney, Ultimo, NSW 2007, Australia
| | - John Beardall
- School of Biological Sciences, Monash University, Building 18, Clayton Campus, Vic 3800, Australia
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Trimborn S, Thoms S, Brenneis T, Heiden JP, Beszteri S, Bischof K. Two Southern Ocean diatoms are more sensitive to ocean acidification and changes in irradiance than the prymnesiophyte Phaeocystis antarctica. PHYSIOLOGIA PLANTARUM 2017; 160:155-170. [PMID: 28019019 DOI: 10.1111/ppl.12539] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/15/2016] [Revised: 11/24/2016] [Accepted: 12/12/2016] [Indexed: 06/06/2023]
Abstract
To better understand the impact of ocean acidification (OA) and changes in light availability on Southern Ocean phytoplankton physiology, we investigated the effects of pCO2 (380 and 800 µatm) in combination with low and high irradiance (20 or 50 and 200 µmol photons m-2 s-1 ) on growth, particulate organic carbon (POC) fixation and photophysiology in the three ecologically relevant species Chaetoceros debilis, Fragilariopsis kerguelensis and Phaeocystis antarctica. Irrespective of the light scenario, neither growth nor POC per cell was stimulated by OA in any of the tested species and the two diatoms even displayed negative responses in growth (e.g. C. debilis) or POC content (e.g. F. kerguelensis) under OA in conjunction with high light. For both diatoms, also maximum quantum yields of photosystem II (Fv /Fm ) were decreased under these conditions, indicating lowered photochemical efficiencies. To counteract the negative effects by OA and high light, the two diatoms showed diverging photoacclimation strategies. While cellular chlorophyll a (Chl a) and fucoxanthin contents were enhanced in C. debilis to potentially maximize light absorption, F. kerguelensis exhibited reduced Chl a per cell, increased disconnection of antennae from photosystem II reaction centers and strongly lowered absolute electron transport rates (ETR). The decline in ETRs in F. kerguelensis might be explained in terms of different species-specific strategies for tuning the available flux of adenosine triphosphate and nicotinamide adenine dinucleotide phosphate. Overall, our results revealed that P. antarctica was more tolerant to OA and changes in irradiance than the two diatoms, which may have important implications for biogeochemical cycling.
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Affiliation(s)
- Scarlett Trimborn
- Department of Biogeosciences, Alfred Wegener Institute for Polar and Marine Research, Bremerhaven, 27515, Germany
- Marine Botany, University of Bremen, Bremen, Germany
| | - Silke Thoms
- Department of Biogeosciences, Alfred Wegener Institute for Polar and Marine Research, Bremerhaven, 27515, Germany
| | - Tina Brenneis
- Department of Biogeosciences, Alfred Wegener Institute for Polar and Marine Research, Bremerhaven, 27515, Germany
| | - Jasmin P Heiden
- Department of Biogeosciences, Alfred Wegener Institute for Polar and Marine Research, Bremerhaven, 27515, Germany
- Marine Botany, University of Bremen, Bremen, Germany
| | - Sara Beszteri
- Department of Biogeosciences, Alfred Wegener Institute for Polar and Marine Research, Bremerhaven, 27515, Germany
| | - Kai Bischof
- Marine Botany, University of Bremen, Bremen, Germany
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Maberly SC, Gontero B. Ecological imperatives for aquatic CO2-concentrating mechanisms. JOURNAL OF EXPERIMENTAL BOTANY 2017; 68:3797-3814. [PMID: 28645178 DOI: 10.1093/jxb/erx201] [Citation(s) in RCA: 43] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
In aquatic environments, the concentration of inorganic carbon is spatially and temporally variable and CO2 can be substantially oversaturated or depleted. Depletion of CO2 plus low rates of diffusion cause inorganic carbon to be more limiting in aquatic than terrestrial environments, and the frequency of species with a CO2-concentrating mechanism (CCM), and their contribution to productivity, is correspondingly greater. Aquatic photoautotrophs may have biochemical or biophysical CCMs and exploit CO2 from the sediment or the atmosphere. Though partly constrained by phylogeny, CCM activity is related to environmental conditions. CCMs are absent or down-regulated when their increased energy costs, lower CO2 affinity, or altered mineral requirements outweigh their benefits. Aquatic CCMs are most widespread in environments with low CO2, high HCO3-, high pH, and high light. Freshwater species are generally less effective at inorganic carbon removal than marine species, but have a greater range of ability to remove carbon, matching the environmental variability in carbon availability. The diversity of CCMs in seagrasses and marine phytoplankton, and detailed mechanistic studies on larger aquatic photoautotrophs are understudied. Strengthening the links between ecology and CCMs will increase our understanding of the mechanisms underlying ecological success and will place mechanistic studies in a clearer ecological context.
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Affiliation(s)
- Stephen C Maberly
- Lake Ecosystems Group, Centre for Ecology & Hydrology, Lancaster Environment Centre, Library Avenue, Bailrigg, Lancaster LA1 4AP, UK
| | - Brigitte Gontero
- Aix Marseille Univ, CNRS, BIP, UMR 7281, IMM, FR 3479, 31 Chemin J. Aiguier, 13 402 Marseille, Cedex 20, France
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Petrou K, Kranz SA, Trimborn S, Hassler CS, Ameijeiras SB, Sackett O, Ralph PJ, Davidson AT. Southern Ocean phytoplankton physiology in a changing climate. JOURNAL OF PLANT PHYSIOLOGY 2016; 203:135-150. [PMID: 27236210 DOI: 10.1016/j.jplph.2016.05.004] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/04/2016] [Revised: 05/04/2016] [Accepted: 05/06/2016] [Indexed: 06/05/2023]
Abstract
The Southern Ocean (SO) is a major sink for anthropogenic atmospheric carbon dioxide (CO2), potentially harbouring even greater potential for additional sequestration of CO2 through enhanced phytoplankton productivity. In the SO, primary productivity is primarily driven by bottom up processes (physical and chemical conditions) which are spatially and temporally heterogeneous. Due to a paucity of trace metals (such as iron) and high variability in light, much of the SO is characterised by an ecological paradox of high macronutrient concentrations yet uncharacteristically low chlorophyll concentrations. It is expected that with increased anthropogenic CO2 emissions and the coincident warming, the major physical and chemical process that govern the SO will alter, influencing the biological capacity and functioning of the ecosystem. This review focuses on the SO primary producers and the bottom up processes that underpin their health and productivity. It looks at the major physico-chemical drivers of change in the SO, and based on current physiological knowledge, explores how these changes will likely manifest in phytoplankton, specifically, what are the physiological changes and floristic shifts that are likely to ensue and how this may translate into changes in the carbon sink capacity, net primary productivity and functionality of the SO.
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Affiliation(s)
- Katherina Petrou
- School of Life Sciences, University of Technology Sydney, 15 Broadway, Ultimo, New South Wales 2007, Australia.
| | - Sven A Kranz
- Florida State University, Department of Earth, Ocean and Atmospheric Sciences, Tallahassee, FL 32306, USA
| | - Scarlett Trimborn
- Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research, Am Handelshafen 12, 27570 Bremerhaven, Germany; University of Bremen, Leobener Straße NW2, 28359 Bremen, Germany
| | - Christel S Hassler
- University of Geneva, Earth and Environmental Sciences, Institut F.-A. Forel, Uni Vogt, 66 bvd Carl-Vogt, 1211 Geneva 4, Switzerland
| | - Sonia Blanco Ameijeiras
- University of Geneva, Earth and Environmental Sciences, Institut F.-A. Forel, Uni Vogt, 66 bvd Carl-Vogt, 1211 Geneva 4, Switzerland
| | - Olivia Sackett
- School of Biological Sciences, Monash University, Melbourne, Victoria, Australia
| | - Peter J Ralph
- Plant Functional Biology and Climate Change Cluster, University of Technology Sydney, 15 Broadway, Ultimo, New South Wales 2007, Australia
| | - Andrew T Davidson
- Department of the Environment, Australian Antarctic Division, 203 Channel Highway, Kingston, Tasmania 7050, Australia; Antarctic Climate and Ecosystem Cooperative Research Centre (ACECRC), University of Tasmania, Private Bag 80, Hobart, Tasmania 7001, Australia
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Young JN, Heureux AMC, Sharwood RE, Rickaby REM, Morel FMM, Whitney SM. Large variation in the Rubisco kinetics of diatoms reveals diversity among their carbon-concentrating mechanisms. JOURNAL OF EXPERIMENTAL BOTANY 2016; 67:3445-56. [PMID: 27129950 PMCID: PMC4892730 DOI: 10.1093/jxb/erw163] [Citation(s) in RCA: 106] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
While marine phytoplankton rival plants in their contribution to global primary productivity, our understanding of their photosynthesis remains rudimentary. In particular, the kinetic diversity of the CO2-fixing enzyme, Rubisco, in phytoplankton remains unknown. Here we quantify the maximum rates of carboxylation (k cat (c)), oxygenation (k cat (o)), Michaelis constants (K m) for CO2 (K C) and O2 (K O), and specificity for CO2 over O2 (SC/O) for Form I Rubisco from 11 diatom species. Diatom Rubisco shows greater variation in K C (23-68 µM), SC/O (57-116mol mol(-1)), and K O (413-2032 µM) relative to plant and algal Rubisco. The broad range of K C values mostly exceed those of C4 plant Rubisco, suggesting that the strength of the carbon-concentrating mechanism (CCM) in diatoms is more diverse, and more effective than previously predicted. The measured k cat (c) for each diatom Rubisco showed less variation (2.1-3.7s(-1)), thus averting the canonical trade-off typically observed between K C and k cat (c) for plant Form I Rubisco. Uniquely, a negative relationship between K C and cellular Rubisco content was found, suggesting variation among diatom species in how they allocate their limited cellular resources between Rubisco synthesis and their CCM. The activation status of Rubisco in each diatom was low, indicating a requirement for Rubisco activase. This work highlights the need to better understand the correlative natural diversity between the Rubisco kinetics and CCM of diatoms and the underpinning mechanistic differences in catalytic chemistry among the Form I Rubisco superfamily.
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Affiliation(s)
- Jodi N Young
- Department of Geosciences, Princeton University, Princeton, NJ 08544, USA
| | - Ana M C Heureux
- Department of Earth Sciences, University of Oxford, South Parks Road, Oxford OX1 3AN, UK
| | - Robert E Sharwood
- Plant Science Division, Research School of Biology, The Australian National University, Canberra, ACT 2601, Australia
| | - Rosalind E M Rickaby
- Department of Earth Sciences, University of Oxford, South Parks Road, Oxford OX1 3AN, UK
| | - François M M Morel
- Department of Geosciences, Princeton University, Princeton, NJ 08544, USA
| | - Spencer M Whitney
- Plant Science Division, Research School of Biology, The Australian National University, Canberra, ACT 2601, Australia
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Abstract
It is difficult to distinguish influx and efflux of inorganic C in photosynthesizing tissues; this article examines what is known and where there are gaps in knowledge. Irreversible decarboxylases produce CO2, and CO2 is the substrate/product of enzymes that act as carboxylases and decarboxylases. Some irreversible carboxylases use CO2; others use HCO3(-). The relative role of permeation through the lipid bilayer versus movement through CO2-selective membrane proteins in the downhill, non-energized, movement of CO2 is not clear. Passive permeation explains most CO2 entry, including terrestrial and aquatic organisms with C3 physiology and biochemistry, terrestrial C4 plants and all crassulacean acid metabolism (CAM) plants, as well as being part of some mechanisms of HCO3(-) use in CO2 concentrating mechanism (CCM) function, although further work is needed to test the mechanism in some cases. However, there is some evidence of active CO2 influx at the plasmalemma of algae. HCO3(-) active influx at the plasmalemma underlies all cyanobacterial and some algal CCMs. HCO3(-) can also enter some algal chloroplasts, probably as part of a CCM. The high intracellular CO2 and HCO3(-) pools consequent upon CCMs result in leakage involving CO2, and occasionally HCO3(-). Leakage from cyanobacterial and microalgal CCMs involves up to half, but sometimes more, of the gross inorganic C entering in the CCM; leakage from terrestrial C4 plants is lower in most environments. Little is known of leakage from other organisms with CCMs, though given the leakage better-examined organisms, leakage occurs and increases the energetic cost of net carbon assimilation.
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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, UK†, and School of Plant Biology, University of Western Australia, M084, 35 Stirling Highway, Crawley, WA 6009, Australia
| | - John Beardall
- School of Biological Sciences, Monash University, VIC 3800, Australia
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Goldman JAL, Kranz SA, Young JN, Tortell PD, Stanley RHR, Bender ML, Morel FMM. Gross and net production during the spring bloom along the Western Antarctic Peninsula. THE NEW PHYTOLOGIST 2015; 205:182-191. [PMID: 25382393 DOI: 10.1111/nph.13125] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/18/2014] [Accepted: 09/15/2014] [Indexed: 06/04/2023]
Abstract
This study explores some of the physiological mechanisms responsible for high productivity near the shelf in the Western Antarctic Peninsula despite a short growing season and cold temperature. We measured gross and net primary production at Palmer Station during the summer of 2012/2013 via three different techniques: incubation with H2 (18) O; incubation with (14) CO2 ; and in situ measurements of O2 /Ar and triple oxygen isotope. Additional laboratory experiments were performed with the psychrophilic diatom Fragilariopsis cylindrus. During the spring bloom, which accounted for more than half of the seasonal gross production at Palmer Station, the ratio of net-to-gross production reached a maximum greater than c. 60%, among the highest ever reported. The use of multiple techniques showed that these high ratios resulted from low heterotrophic respiration and very low daylight autotrophic respiration. Laboratory experiments revealed a similar ratio of net-to-gross O2 production in F. cylindrus and provided the first experimental evidence for an important level of cyclic electron flow (CEF) in this organism. The low ratio of community respiration to gross primary production observed during the bloom at Palmer Station may be characteristic of high latitude coastal ecosystems and partially supported by a very active CEF in psychrophilic phytoplankton.
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