1
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Jones SW, Campbell FC, Campbell DA. Revision of Failed Nonanatomic Extensor Retinacular Stabilization of the Unstable ECU Tendon: Surgical Technique and Case Series. Tech Hand Up Extrem Surg 2024; 28:67-73. [PMID: 38088179 DOI: 10.1097/bth.0000000000000467] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/21/2024]
Abstract
Nonanatomic surgical stabilization of the unstable extensor carpi ulnaris (ECU) tendon (where the subluxing tendon is re-routed away from the bony groove in the distal ulna) utilizes a flap of extensor retinaculum to create a new retaining sheath that will stabilize the tendon during forearm rotation movements. When this surgery fails, the extensor retinaculum tissue does not regenerate with sufficient structural strength to be used again. Previously, a different approach has then been needed for revision surgery, often using more complex surgical techniques with a substantially greater impact on recovery. We describe a highly reliable yet simple method of using local soft tissue to adequately restabilize the subluxing ECU tendon in cases where an extensor retinacular flap has already been used. We report the results of this technique in 4 patients, all of whom returned to jobs/hobbies where ECU instability was a considerable functional risk.
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Affiliation(s)
- Stuart W Jones
- Department of Trauma & Orthopaedic Surgery, Airedale NHS Foundation Trust, Keighley
| | - Fiona C Campbell
- Department of Acute and General Medicine, Harrogate NHS Foundation Trust, Harrogate
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2
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Joli N, Concia L, Mocaer K, Guterman J, Laude J, Guerin S, Sciandra T, Bruyant F, Ait-Mohamed O, Beguin M, Forget MH, Bourbousse C, Lacour T, Bailleul B, Nef C, Savoie M, Tremblay JE, Campbell DA, Lavaud J, Schwab Y, Babin M, Bowler C. Hypometabolism to survive the long polar night and subsequent successful return to light in the diatom Fragilariopsis cylindrus. New Phytol 2024; 241:2193-2208. [PMID: 38095198 DOI: 10.1111/nph.19387] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/20/2023] [Accepted: 10/17/2023] [Indexed: 02/09/2024]
Abstract
Diatoms, the main eukaryotic phytoplankton of the polar marine regions, are essential for the maintenance of food chains specific to Arctic and Antarctic ecosystems, and are experiencing major disturbances under current climate change. As such, it is fundamental to understand the physiological mechanisms and associated molecular basis of their endurance during the long polar night. Here, using the polar diatom Fragilariopsis cylindrus, we report an integrative analysis combining transcriptomic, microscopic and biochemical approaches to shed light on the strategies used to survive the polar night. We reveal that in prolonged darkness, diatom cells enter a state of quiescence with reduced metabolic and transcriptional activity, during which no cell division occurs. We propose that minimal energy is provided by respiration and degradation of protein, carbohydrate and lipid stores and that homeostasis is maintained by autophagy in prolonged darkness. We also report internal structural changes that manifest the morphological acclimation of cells to darkness, including the appearance of a large vacuole. Our results further show that immediately following a return to light, diatom cells are able to use photoprotective mechanisms and rapidly resume photosynthesis, demonstrating the remarkable robustness of polar diatoms to prolonged darkness at low temperature.
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Affiliation(s)
- Nathalie Joli
- Institut de Biologie de l'École Normale Supérieure (IBENS), École Normale Supérieure, CNRS, INSERM, PSL Université Paris, 75005, Paris, France
| | - Lorenzo Concia
- Institut de Biologie de l'École Normale Supérieure (IBENS), École Normale Supérieure, CNRS, INSERM, PSL Université Paris, 75005, Paris, France
| | - Karel Mocaer
- Cell Biology and Biophysics Unit, European Molecular Biology Laboratory (EMBL) & Collaboration for Joint PhD Degree between the European Molecular Biology Laboratory and the Heidelberg University, Faculty of Biosciences, 69117, Heidelberg, Germany
| | - Julie Guterman
- Institut de Biologie de l'École Normale Supérieure (IBENS), École Normale Supérieure, CNRS, INSERM, PSL Université Paris, 75005, Paris, France
| | - Juliette Laude
- Institut de Biologie de l'École Normale Supérieure (IBENS), École Normale Supérieure, CNRS, INSERM, PSL Université Paris, 75005, Paris, France
| | - Sebastien Guerin
- Takuvik International Research Laboratory, Université Laval (Canada) & CNRS (France), Département de Biologie and Québec-Océan, Université Laval, Québec, QC, G1V 0A6, Canada
| | - Theo Sciandra
- Institut de Biologie de l'École Normale Supérieure (IBENS), École Normale Supérieure, CNRS, INSERM, PSL Université Paris, 75005, Paris, France
- Takuvik International Research Laboratory, Université Laval (Canada) & CNRS (France), Département de Biologie and Québec-Océan, Université Laval, Québec, QC, G1V 0A6, Canada
| | - Flavienne Bruyant
- Takuvik International Research Laboratory, Université Laval (Canada) & CNRS (France), Département de Biologie and Québec-Océan, Université Laval, Québec, QC, G1V 0A6, Canada
| | - Ouardia Ait-Mohamed
- Institut de Biologie de l'École Normale Supérieure (IBENS), École Normale Supérieure, CNRS, INSERM, PSL Université Paris, 75005, Paris, France
| | - Marine Beguin
- Takuvik International Research Laboratory, Université Laval (Canada) & CNRS (France), Département de Biologie and Québec-Océan, Université Laval, Québec, QC, G1V 0A6, Canada
| | - Marie-Helene Forget
- Takuvik International Research Laboratory, Université Laval (Canada) & CNRS (France), Département de Biologie and Québec-Océan, Université Laval, Québec, QC, G1V 0A6, Canada
| | - Clara Bourbousse
- Institut de Biologie de l'École Normale Supérieure (IBENS), École Normale Supérieure, CNRS, INSERM, PSL Université Paris, 75005, Paris, France
| | - Thomas Lacour
- Laboratoire PHYSiologie des micro ALGues (PDG-ODE-PHYTOX-PHYSALG), Centre Atlantique, 44 311, Nantes, France
| | - Benjamin Bailleul
- Laboratory of Chloroplast Biology and Light Sensing in Microalgae, Institut de Biologie Physico Chimique, CNRS, Sorbonne Université, Paris, 75005, France
| | - Charlotte Nef
- Institut de Biologie de l'École Normale Supérieure (IBENS), École Normale Supérieure, CNRS, INSERM, PSL Université Paris, 75005, Paris, France
| | - Mireille Savoie
- Département de Biologie, Université Laval, Québec, QC, G1V 0A6, Canada
| | | | | | - Johann Lavaud
- Takuvik International Research Laboratory, Université Laval (Canada) & CNRS (France), Département de Biologie and Québec-Océan, Université Laval, Québec, QC, G1V 0A6, Canada
- UMR 6539 LEMAR-Laboratory of Environmental Marine Sciences, CNRS/Univ Brest/Ifremer/IRD, IUEM-Institut Européen de la Mer, Technopôle Brest-Iroise, rue Dumont d'Urville, 29280, Plouzané, France
| | - Yannick Schwab
- Cell Biology and Biophysics Unit and Electron Microscopy Core Facility, European Molecular Biology Laboratory (EMBL), 69117, Heidelberg, Germany
| | - Marcel Babin
- Takuvik International Research Laboratory, Université Laval (Canada) & CNRS (France), Département de Biologie and Québec-Océan, Université Laval, Québec, QC, G1V 0A6, Canada
| | - Chris Bowler
- Institut de Biologie de l'École Normale Supérieure (IBENS), École Normale Supérieure, CNRS, INSERM, PSL Université Paris, 75005, Paris, France
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3
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Morelle J, Bastos A, Frankenbach S, Frommlet JC, Campbell DA, Lavaud J, Serôdio J. The Photoprotective Behavior of a Motile Benthic Diatom as Elucidated from the Interplay Between Cell Motility and Physiological Responses to a Light Microgradient Using a Novel Experimental Setup. Microb Ecol 2024; 87:40. [PMID: 38351424 PMCID: PMC10864569 DOI: 10.1007/s00248-024-02354-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/19/2023] [Accepted: 01/26/2024] [Indexed: 02/16/2024]
Abstract
It has long been hypothesized that benthic motile pennate diatoms use phototaxis to optimize photosynthesis and minimize photoinhibitory damage by adjusting their position within vertical light gradients in coastal benthic sediments. However, experimental evidence to test this hypothesis remains inconclusive, mainly due to methodological difficulties in studying cell behavior and photosynthesis over realistic spatial microscale gradients of irradiance and cell position. In this study, a novel experimental approach was developed and used to test the hypothesis of photosynthesis optimization through motility, based on the combination of single-cell in vivo chlorophyll fluorometry and microfluidic chips. The approach allows the concurrent study of behavior and photosynthetic activity of individual cells of the epipelic diatom species Craspedostauros britannicus exposed to a light microgradient of realistic dimensions, simulating the irradiance and distance scales of light microgradients in benthic sediments. Following exposure to light, (i) cells explored their light environment before initiating light-directed motility; (ii) cells used motility to lower their light dose, when exposed to the highest light intensities; and (iii) motility was combined with reversible non-photochemical quenching, to allow cells to avoid photoinhibition. The results of this proof-of-concept study not only strongly support the photoprotective nature of photobehavior in the studied species but also revealed considerable variability in how individual cells reacted to a light microgradient. The experimental setup can be readily applied to study motility and photosynthetic light responses of other diatom species or natural assemblages, as well as other photoautotrophic motile microorganisms, broadening the toolset for experimental microbial ecology research.
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Affiliation(s)
- Jérôme Morelle
- CESAM-Centre for Environmental and Marine Studies and Department of Biology, University of Aveiro, Campus de Santiago, 3810-193, Aveiro, Portugal.
| | - Alexandra Bastos
- CESAM-Centre for Environmental and Marine Studies and Department of Biology, University of Aveiro, Campus de Santiago, 3810-193, Aveiro, Portugal
| | - Silja Frankenbach
- CESAM-Centre for Environmental and Marine Studies and Department of Biology, University of Aveiro, Campus de Santiago, 3810-193, Aveiro, Portugal
| | - Jörg C Frommlet
- CESAM-Centre for Environmental and Marine Studies and Department of Biology, University of Aveiro, Campus de Santiago, 3810-193, Aveiro, Portugal
| | | | - Johann Lavaud
- LEMAR-Laboratory of Marine Environmental Sciences, UMR 6539 CNRS, Univ Brest, Ifremer, IRD, Institut Universitaire Européen de La Mer, Technopôle Brest-Iroise, Plouzané, France
| | - João Serôdio
- CESAM-Centre for Environmental and Marine Studies and Department of Biology, University of Aveiro, Campus de Santiago, 3810-193, Aveiro, Portugal
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4
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Moore LR, Caspi R, Campbell DA, Casey JR, Crevecoeur S, Lea-Smith DJ, Long B, Omar NM, Paley SM, Schmelling NM, Torrado A, Zehr JP, Karp PD. CyanoCyc cyanobacterial web portal. Front Microbiol 2024; 15:1340413. [PMID: 38357349 PMCID: PMC10864581 DOI: 10.3389/fmicb.2024.1340413] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2023] [Accepted: 01/11/2024] [Indexed: 02/16/2024] Open
Abstract
CyanoCyc is a web portal that integrates an exceptionally rich database collection of information about cyanobacterial genomes with an extensive suite of bioinformatics tools. It was developed to address the needs of the cyanobacterial research and biotechnology communities. The 277 annotated cyanobacterial genomes currently in CyanoCyc are supplemented with computational inferences including predicted metabolic pathways, operons, protein complexes, and orthologs; and with data imported from external databases, such as protein features and Gene Ontology (GO) terms imported from UniProt. Five of the genome databases have undergone manual curation with input from more than a dozen cyanobacteria experts to correct errors and integrate information from more than 1,765 published articles. CyanoCyc has bioinformatics tools that encompass genome, metabolic pathway and regulatory informatics; omics data analysis; and comparative analyses, including visualizations of multiple genomes aligned at orthologous genes, and comparisons of metabolic networks for multiple organisms. CyanoCyc is a high-quality, reliable knowledgebase that accelerates scientists' work by enabling users to quickly find accurate information using its powerful set of search tools, to understand gene function through expert mini-reviews with citations, to acquire information quickly using its interactive visualization tools, and to inform better decision-making for fundamental and applied research.
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Affiliation(s)
| | - Ron Caspi
- SRI International, Menlo Park, CA, United States
| | | | - John R. Casey
- Lawrence Livermore National Laboratory, Physical and Life Sciences Directorate, Livermore, CA, United States
| | - Sophie Crevecoeur
- Watershed Hydrology and Ecology Research Division, Environment and Climate Change Canada, Burlington, ON, Canada
| | - David J. Lea-Smith
- School of Biological Sciences, University of East Anglia, Norwich, United Kingdom
| | - Bin Long
- Department of Plant Pathology and Microbiology, Texas A&M University, College Station, TX, United States
| | | | | | | | - Alejandro Torrado
- Institute of Plant Biochemistry and Photosynthesis, University of Seville and Spanish National Research Council, Sevilla, Spain
| | - Jonathan P. Zehr
- Ocean Sciences Department, University of California, Santa Cruz, Santa Cruz, CA, United States
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Berthold M, Albrecht M, Campbell DA, Omar NM. Draft genomes of 3 cyanobacteria strains and 17 co-habiting proteobacteria assembled from metagenomes. Microbiol Resour Announc 2023; 12:e0046023. [PMID: 37943043 PMCID: PMC10720521 DOI: 10.1128/mra.00460-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2023] [Accepted: 10/12/2023] [Indexed: 11/10/2023] Open
Abstract
Cyanobium and Synechococcus are prominent, globally distributed cyanobacteria genera with ecological significance. Here, we report the genomes of the marine Synechococcus sp. CCMP836 and two strains of Cyanobium (CZS25K and CZS48M) along with the genomes of 17 co-occurring proteobacteria. These genomes will improve the strain-specific ecological positions.
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Affiliation(s)
| | - Martin Albrecht
- Institute of Biological Sciences, University of Rostock, Rostock, Germany
| | | | - Naaman M. Omar
- Department of Biology, Mount Allison University, Sackville, Canada
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6
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Li W, Wang T, Campbell DA, Gao K. Light history modulates growth and photosynthetic responses of a diatom to ocean acidification and UV radiation. Mar Life Sci Technol 2023; 5:116-125. [PMID: 37073326 PMCID: PMC10077217 DOI: 10.1007/s42995-022-00138-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/06/2022] [Accepted: 06/08/2022] [Indexed: 05/03/2023]
Abstract
To examine the synergetic effects of ocean acidification (OA) and light intensity on the photosynthetic performance of marine diatoms, the marine centric diatom Thalassiosira weissflogii was cultured under ambient low CO2 (LC, 390 μatm) and elevated high CO2 (HC, 1000 μatm) levels under low-light (LL, 60 μmol m-2 s-1) or high-light (HL, 220 μmol m-2 s-1) conditions for over 20 generations. HL stimulated the growth rate by 128 and 99% but decreased cell size by 9 and 7% under LC and HC conditions, respectively. However, HC did not change the growth rate under LL but decreased it by 9% under HL. LL combined with HC decreased both maximum quantum yield (F V/F M) and effective quantum yield (Φ PSII), measured under either low or high actinic light. When exposed to UV radiation (UVR), LL-grown cells were more prone to UVA exposure, with higher UVA and UVR inducing inhibition of Φ PSII compared with HL-grown cells. Light use efficiency (α) and maximum relative electron transport rate (rETRmax) were inhibited more in the HC-grown cells when UVR (UVA and UVB) was present, particularly under LL. Our results indicate that the growth light history influences the cell growth and photosynthetic responses to OA and UVR. Supplementary Information The online version contains supplementary material available at 10.1007/s42995-022-00138-x.
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Affiliation(s)
- Wei Li
- State Key Laboratory of Marine Environmental Science & College of Ocean and Earth Science, Xiamen University, Xiamen, 361005 China
- College of Life and Environmental Sciences, Huangshan University, Huangshan, 245041 China
| | - Tifeng Wang
- State Key Laboratory of Marine Environmental Science & College of Ocean and Earth Science, Xiamen University, Xiamen, 361005 China
| | | | - Kunshan Gao
- State Key Laboratory of Marine Environmental Science & College of Ocean and Earth Science, Xiamen University, Xiamen, 361005 China
- Co-innovation Center of Jiangsu Marine Bio-industry Technology, Jiangsu Ocean University, Lianyungang, 222005 China
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7
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Omar NM, Fleury K, Beardsall B, Prášil O, Campbell DA. Genomic capacities for Reactive Oxygen Species metabolism across marine phytoplankton. PLoS One 2023; 18:e0284580. [PMID: 37098087 PMCID: PMC10128935 DOI: 10.1371/journal.pone.0284580] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2022] [Accepted: 04/04/2023] [Indexed: 04/26/2023] Open
Abstract
Marine phytoplankton produce and scavenge Reactive Oxygen Species, to support cellular processes, while limiting damaging reactions. Some prokaryotic picophytoplankton have, however, lost all genes encoding scavenging of hydrogen peroxide. Such losses of metabolic function can only apply to Reactive Oxygen Species which potentially traverse the cell membrane outwards, before provoking damaging intracellular reactions. We hypothesized that cell radius influences which elements of Reactive Oxygen Species metabolism are partially or fully dispensable from a cell. We therefore investigated genomes and transcriptomes from diverse marine eukaryotic phytoplankton, ranging from 0.4 to 44 μm radius, to analyze the genomic allocations encoding enzymes metabolizing Reactive Oxygen Species. Superoxide has high reactivity, short lifetimes and limited membrane permeability. Genes encoding superoxide scavenging are ubiquitous across phytoplankton, but the fractional gene allocation decreased with increasing cell radius, consistent with a nearly fixed set of core genes for scavenging superoxide pools. Hydrogen peroxide has lower reactivity, longer intracellular and extracellular lifetimes and readily crosses cell membranes. Genomic allocations to both hydrogen peroxide production and scavenging decrease with increasing cell radius. Nitric Oxide has low reactivity, long intracellular and extracellular lifetimes and readily crosses cell membranes. Neither Nitric Oxide production nor scavenging genomic allocations changed with increasing cell radius. Many taxa, however, lack the genomic capacity for nitric oxide production or scavenging. The probability of presence of capacity to produce nitric oxide decreases with increasing cell size, and is influenced by flagella and colony formation. In contrast, the probability of presence of capacity to scavenge nitric oxide increases with increasing cell size, and is again influenced by flagella and colony formation.
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Affiliation(s)
- Naaman M Omar
- Department of Biology, Mount Allison University, Sackville, NB, Canada
| | - Katherine Fleury
- Department of Biology, Mount Allison University, Sackville, NB, Canada
- Faculty of Veterinary Medicine, University of Calgary, Calgary, AB, Canada
| | - Brian Beardsall
- Department of Biology, Mount Allison University, Sackville, NB, Canada
- Faculty of Computer Science, Dalhousie University, Halifax, NS, Canada
| | - Ondřej Prášil
- Institute of Microbiology, Center Algatech, Laboratory of Photosynthesis, Trebon, CZ, Czech Republic
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8
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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] [What about the content of this article? (0)] [Affiliation(s)] [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
- * E-mail:
| | - 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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9
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Omar NM, Prášil O, McCain JSP, Campbell DA. Diffusional Interactions among Marine Phytoplankton and Bacterioplankton: Modelling H 2O 2 as a Case Study. Microorganisms 2022; 10:821. [PMID: 35456871 PMCID: PMC9030875 DOI: 10.3390/microorganisms10040821] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2022] [Revised: 04/12/2022] [Accepted: 04/13/2022] [Indexed: 02/04/2023] Open
Abstract
Marine phytoplankton vary widely in size across taxa, and in cell suspension densities across habitats and growth states. Cell suspension density and total biovolume determine the bulk influence of a phytoplankton community upon its environment. Cell suspension density also determines the intercellular spacings separating phytoplankton cells from each other, or from co-occurring bacterioplankton. Intercellular spacing then determines the mean diffusion paths for exchanges of solutes among co-occurring cells. Marine phytoplankton and bacterioplankton both produce and scavenge reactive oxygen species (ROS), to maintain intracellular ROS homeostasis to support their cellular processes, while limiting damaging reactions. Among ROS, hydrogen peroxide (H2O2) has relatively low reactivity, long intracellular and extracellular lifetimes, and readily crosses cell membranes. Our objective was to quantify how cells can influence other cells via diffusional interactions, using H2O2 as a case study. To visualize and constrain potentials for cell-to-cell exchanges of H2O2, we simulated the decrease of [H2O2] outwards from representative phytoplankton taxa maintaining internal [H2O2] above representative seawater [H2O2]. [H2O2] gradients outwards from static cell surfaces were dominated by volumetric dilution, with only a negligible influence from decay. The simulated [H2O2] fell to background [H2O2] within ~3.1 µm from a Prochlorococcus cell surface, but extended outwards 90 µm from a diatom cell surface. More rapid decays of other, less stable ROS, would lower these threshold distances. Bacterioplankton lowered simulated local [H2O2] below background only out to 1.2 µm from the surface of a static cell, even though bacterioplankton collectively act to influence seawater ROS. These small diffusional spheres around cells mean that direct cell-to-cell exchange of H2O2 is unlikely in oligotrophic habits with widely spaced, small cells; moderate in eutrophic habits with shorter cell-to-cell spacing; but extensive within phytoplankton colonies.
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Affiliation(s)
- Naaman M. Omar
- Department of Biology, Mount Allison University, Sackville, NB E4L1G7, Canada;
| | - Ondřej Prášil
- Center Algatech, Laboratory of Photosynthesis, Novohradska 237, CZ 37981 Trebon, Czech Republic;
| | - J. Scott P. McCain
- Department of Biology, Massachusetts Institute of Technology, Boston, MA 02142, USA;
| | - Douglas A. Campbell
- Department of Biology, Mount Allison University, Sackville, NB E4L1G7, Canada;
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10
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Polerecky L, Eichner M, Masuda T, Zavřel T, Rabouille S, Campbell DA, Halsey K. Calculation and Interpretation of Substrate Assimilation Rates in Microbial Cells Based on Isotopic Composition Data Obtained by nanoSIMS. Front Microbiol 2021; 12:621634. [PMID: 34917040 PMCID: PMC8670600 DOI: 10.3389/fmicb.2021.621634] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2020] [Accepted: 11/08/2021] [Indexed: 11/17/2022] Open
Abstract
Stable isotope probing (SIP) combined with nano-scale secondary ion mass spectrometry (nanoSIMS) is a powerful approach to quantify assimilation rates of elements such as C and N into individual microbial cells. Here, we use mathematical modeling to investigate how the derived rate estimates depend on the model used to describe substrate assimilation by a cell during a SIP incubation. We show that the most commonly used model, which is based on the simplifying assumptions of linearly increasing biomass of individual cells over time and no cell division, can yield underestimated assimilation rates when compared to rates derived from a model that accounts for cell division. This difference occurs because the isotopic labeling of a dividing cell increases more rapidly over time compared to a non-dividing cell and becomes more pronounced as the labeling increases above a threshold value that depends on the cell cycle stage of the measured cell. Based on the modeling results, we present formulae for estimating assimilation rates in cells and discuss their underlying assumptions, conditions of applicability, and implications for the interpretation of intercellular variability in assimilation rates derived from nanoSIMS data, including the impacts of storage inclusion metabolism. We offer the formulae as a Matlab script to facilitate rapid data evaluation by nanoSIMS users.
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Affiliation(s)
- Lubos Polerecky
- Department of Earth Sciences, Utrecht University, Utrecht, Netherlands
| | - Meri Eichner
- Institute of Microbiology, Czech Academy of Sciences, Centre Algatech, Třeboň, Czechia
| | - Takako Masuda
- Institute of Microbiology, Czech Academy of Sciences, Centre Algatech, Třeboň, Czechia
| | - Tomáš Zavřel
- Global Change Research Institute, Czech Academy of Sciences, Brno, Czechia
| | - Sophie Rabouille
- Sorbonne Université, CNRS, Laboratoire d'Océanographie de Villefranche, LOV, Villefranche-sur-mer, France.,Sorbonne Université, CNRS, Laboratoire d'Océanographie Microbienne, LOMIC, Banyuls-sur-mer, France
| | | | - Kimberly Halsey
- Department of Microbiology, Oregon State University, Corvallis, OR, United States
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11
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Berthold M, Campbell DA. Restoration, conservation and phytoplankton hysteresis. Conserv Physiol 2021; 9:coab062. [PMID: 34394942 PMCID: PMC8361504 DOI: 10.1093/conphys/coab062] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/26/2020] [Revised: 06/10/2021] [Accepted: 07/22/2021] [Indexed: 06/13/2023]
Abstract
Phytoplankton growth depends not only upon external factors that are not strongly altered by the presence of phytoplankton, such as temperature, but also upon factors that are strongly influenced by activity of phytoplankton, including photosynthetically active radiation, and the availability of the macronutrients carbon, nitrogen, phosphorus and, for some, silicate. Since phytoplankton therefore modify, and to an extent create, their own habitats, established phytoplankton communities can show resistance and resilience to change, including managed changes in nutrient regimes. Phytoplankton blooms and community structures can be predicted from the overall biogeochemical setting and inputs, but restorations may be influenced by the physiological responses of established phytoplankton taxa to nutrient inputs, temperature, second-order changes in illumination and nutrient recycling. In this review we discuss the contributions of phytoplankton ecophysiology to biogeochemical hysteresis and possible effects on community composition in the face of management, conservation or remediation plans.
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Affiliation(s)
- Maximilian Berthold
- Department of Biology, Mount Allison University, Sackville, New Brunswick E4L 1C9, Canada
| | - Douglas A Campbell
- Department of Biology, Mount Allison University, Sackville, New Brunswick E4L 1C9, Canada
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12
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Rabouille S, Campbell DA, Masuda T, Zavřel T, Bernát G, Polerecky L, Halsey K, Eichner M, Kotabová E, Stephan S, Lukeš M, Claquin P, Bonomi-Barufi J, Lombardi AT, Červený J, Suggett DJ, Giordano M, Kromkamp JC, Prášil O. Electron & Biomass Dynamics of Cyanothece Under Interacting Nitrogen & Carbon Limitations. Front Microbiol 2021; 12:617802. [PMID: 33897635 PMCID: PMC8063122 DOI: 10.3389/fmicb.2021.617802] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2020] [Accepted: 03/01/2021] [Indexed: 11/25/2022] Open
Abstract
Marine diazotrophs are a diverse group with key roles in biogeochemical fluxes linked to primary productivity. The unicellular, diazotrophic cyanobacterium Cyanothece is widely found in coastal, subtropical oceans. We analyze the consequences of diazotrophy on growth efficiency, compared to NO3–-supported growth in Cyanothece, to understand how cells cope with N2-fixation when they also have to face carbon limitation, which may transiently affect populations in coastal environments or during blooms of phytoplankton communities. When grown in obligate diazotrophy, cells face the double burden of a more ATP-demanding N-acquisition mode and additional metabolic losses imposed by the transient storage of reducing potential as carbohydrate, compared to a hypothetical N2 assimilation directly driven by photosynthetic electron transport. Further, this energetic burden imposed by N2-fixation could not be alleviated, despite the high irradiance level within the cultures, because photosynthesis was limited by the availability of dissolved inorganic carbon (DIC), and possibly by a constrained capacity for carbon storage. DIC limitation exacerbates the costs on growth imposed by nitrogen fixation. Therefore, the competitive efficiency of diazotrophs could be hindered in areas with insufficient renewal of dissolved gases and/or with intense phytoplankton biomass that both decrease available light energy and draw the DIC level down.
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Affiliation(s)
- Sophie Rabouille
- Sorbonne Université, CNRS, LOV, Villefranche-sur-Mer, France.,Sorbonne Université, CNRS, LOMIC, Banyuls-sur-Mer, France
| | - Douglas A Campbell
- Centre Algatech, Institute of Microbiology of the Czech Academy of Sciences, Třeboň, Czechia.,Mount Allison University, Sackville, NB, Canada
| | - Takako Masuda
- Centre Algatech, Institute of Microbiology of the Czech Academy of Sciences, Třeboň, Czechia
| | - Tomáš Zavřel
- Department of Adaptive Biotechnologies, Global Change Research Institute CAS, Brno, Czechia
| | - Gábor Bernát
- Centre Algatech, Institute of Microbiology of the Czech Academy of Sciences, Třeboň, Czechia.,Centre for Ecological Research, Balaton Limnological Institute, Klebelsberg Kuno u. 3. 8237 Tihany, Hungary
| | - Lubos Polerecky
- Department of Earth Sciences, Utrecht University, Utrecht, Netherlands
| | - Kimberly Halsey
- Department of Microbiology, Oregon State University, Corvallis, OR, United States
| | - Meri Eichner
- Centre Algatech, Institute of Microbiology of the Czech Academy of Sciences, Třeboň, Czechia.,Max Planck Institute for Marine Microbiology, Bremen, Germany
| | - Eva Kotabová
- Centre Algatech, Institute of Microbiology of the Czech Academy of Sciences, Třeboň, Czechia
| | - Susanne Stephan
- Leibniz-Institute of Freshwater Ecology and Inland Fisheries, Zur alten Fischerhütte 2, Stechlin, Germany.,Department of Ecology, Berlin Institute of Technology (TU Berlin), Ernst-Reuter-Platz 1, Berlin, Germany
| | - Martin Lukeš
- Centre Algatech, Institute of Microbiology of the Czech Academy of Sciences, Třeboň, Czechia
| | - Pascal Claquin
- UMR BOREA (CNRS 8067), MNHN, IRD (207), Université de Caen Basse-Normandie, Caen, France
| | - José Bonomi-Barufi
- Departamento de Botânica, Centro de Ciências Biológicas, Universidade Federal de Santa Catarina, Florianópolis, Brazil
| | | | - Jan Červený
- Department of Adaptive Biotechnologies, Global Change Research Institute CAS, Brno, Czechia
| | - David J Suggett
- University of Technology Sydney, Climate Change Cluster, Faculty of Science, Ultimo, NSW, Australia
| | - Mario Giordano
- Centre Algatech, Institute of Microbiology of the Czech Academy of Sciences, Třeboň, Czechia.,Dipartimento di Scienze della Vita e dell'Ambiente, UniversitaÌ Politecnica delle Marche, Ancona, Italy
| | - Jacco C Kromkamp
- NIOZ Royal Netherlands Institute for Sea Research and Utrecht University, Utrecht, Netherlands
| | - Ondřej Prášil
- Centre Algatech, Institute of Microbiology of the Czech Academy of Sciences, Třeboň, Czechia
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13
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Qu L, Campbell DA, Gao K. Ocean acidification interacts with growth light to suppress CO 2 acquisition efficiency and enhance mitochondrial respiration in a coastal diatom. Mar Pollut Bull 2021; 163:112008. [PMID: 33461076 DOI: 10.1016/j.marpolbul.2021.112008] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/16/2020] [Revised: 12/27/2020] [Accepted: 12/28/2020] [Indexed: 06/12/2023]
Abstract
Diatom responses to ocean acidification have been documented with variable and controversial results. We grew the coastal diatom Thalassiosira weissflogii under 410 (LC, pH 8.13) vs 1000 μatm (HC, pH 7.83) pCO2 and at different levels of light (80, 140, 220 μmol photons m-2 s-1), and found that light level alters physiological responses to OA. CO2 concentrating mechanisms (CCMs) were down-regulated in the HC-grown cells across all the light levels, as reflected by lowered activity of the periplasmic carbonic anhydrase and decreased photosynthetic affinity for CO2 or dissolved inorganic carbon. The specific growth rate was, however, enhanced significantly by 9.2% only at the limiting low light level. These results indicate that rather than CO2 "fertilization", the energy saved from down-regulation of CCMs promoted the growth rate of the diatom when light availability is low, in parallel with enhanced respiration under OA to cope with the acidic stress by providing extra energy.
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Affiliation(s)
- Liming Qu
- State Key Laboratory of Marine Environmental Science & College of Ocean and Earth Sciences, Xiamen University, Xiamen, China
| | - Douglas A Campbell
- Biology Department, Mount Allison University, Sackville, NB E4L 1G7, Canada
| | - Kunshan Gao
- State Key Laboratory of Marine Environmental Science & College of Ocean and Earth Sciences, Xiamen University, Xiamen, China; Co-Innovation Center of Jiangsu Marine Bio-industry Technology, Jiangsu Ocean University, Lianyungang 222005, China.
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14
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Serôdio J, Campbell DA. Photoinhibition in optically thick samples: Effects of light attenuation on chlorophyll fluorescence-based parameters. J Theor Biol 2021; 513:110580. [PMID: 33444625 DOI: 10.1016/j.jtbi.2021.110580] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2020] [Revised: 12/15/2020] [Accepted: 01/04/2021] [Indexed: 11/25/2022]
Abstract
Oxygenic photoautotrophs are, paradoxically, subject to photoinhibition of their photosynthetic apparatus, in particular one of its major components, the Photosystem II (PSII). Photoinhibition is generalized across species, light conditions and habitats, imposing substantial metabolic costs that lower photosynthetic productivity and constrain the niches of photoautotrophy. As a process driven by light reaching PSII, light attenuation in optically thick samples influences both the actual extent, and the detection, of photoinhibition. Chlorophyll fluorescence is widely used to measure photoinhibition, but fluorescence-based parameters are affected by light attenuation of both downwelling incident radiation traversing the sample to reach PSII, and emitted fluorescence upwelling through the sample. We used modelling, experimental manipulation of within-sample light attenuation, and meta-analysis of published data, to show substantial, differential effects of light attenuation and depth-integration of emitted fluorescence upon measurements of photoinhibition. Numerical simulations and experimental manipulation of light attenuation indicated that PSII photoinactivation tracked using chlorophyll fluorescence can appear to be over three times lower than the inherent cellular susceptibility to photoinactivation, in optically-dense samples such as leaves or biofilms. The meta-analysis of published data showed that this general trend was unknowingly present in the literature, revealing an overall difference of more than five times between optically thick leaves and optically thin cell suspensions. Although fluorescence-based parameters may provide ecophysiologically relevant information for characterizing the sample as a whole, light attenuation and depth integration can vary between samples independently of their intrinsic physiology. They should be used with caution when aiming to quantify in absolute terms inherent photoinhibition-related parameters in optically thick samples.
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Affiliation(s)
- João Serôdio
- Department of Biology and CESAM - Centre for Environmental and Marine Studies, University of Aveiro, Campus de Santiago, 3810-193 Aveiro, Portugal.
| | - Douglas A Campbell
- Department of Biology, Mount Allison University, Sackville, Canada NB E4L 3G7, Canada
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15
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Li W, Wang T, Campbell DA, Gao K. Ocean acidification interacts with variable light to decrease growth but increase particulate organic nitrogen production in a diatom. Mar Environ Res 2020; 160:104965. [PMID: 32291249 DOI: 10.1016/j.marenvres.2020.104965] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/12/2019] [Revised: 03/06/2020] [Accepted: 03/21/2020] [Indexed: 06/11/2023]
Abstract
Phytoplankton in the upper oceans are exposed to changing light levels due to mixing, diurnal solar cycles and weather conditions. Consequently, effects of ocean acidification are superimposed upon responses to variable light levels. We therefore grew a model diatom Thalassiosira pseudonana under either constant or variable light but at the same daily photon dose, with current low (400 μatm, LC) and future high CO2 (1000 μatm, HC) treatments. Variable light, compared with the constant light regime, decreased the growth rate, Chl a, Chl c, and carotenoid contents under both LC and HC conditions. Cells grown under variable light appeared more tolerant of high light as indicated by higher maximum relative electron transport rate and saturation light. Light variation interacted with high CO2/lowered pH to decrease the carbon fixation rate, but increased particulate organic carbon (POC) and particularly nitrogen (PON) per cell, which drove a decrease in C/N ratio, reflecting changes in the efficiency of energy transfer from photo-chemistry to net biomass production. Our results imply that elevated pCO2 under varying light conditions can lead to less primary productivity but more PON per biomass of the diatom, which might improve the food quality of diatoms and thereby influence biogeochemical nitrogen cycles.
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Affiliation(s)
- Wei Li
- State Key Laboratory of Marine Environmental Science & College of Ocean and Earth Sciences, Xiamen University, Xiamen, 361005, China; College of Life and Environmental Sciences, Huangshan University, Huangshan, 245041, China
| | - Tifeng Wang
- State Key Laboratory of Marine Environmental Science & College of Ocean and Earth Sciences, Xiamen University, Xiamen, 361005, China
| | - Douglas A Campbell
- Biology Department, Mount Allison University, Sackville, NB, E4L 1G7, Canada
| | - Kunshan Gao
- State Key Laboratory of Marine Environmental Science & College of Ocean and Earth Sciences, Xiamen University, Xiamen, 361005, China.
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16
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Bonnanfant M, Jesus B, Pruvost J, Mouget JL, Campbell DA. Photosynthetic electron transport transients in Chlorella vulgaris under fluctuating light. ALGAL RES 2019. [DOI: 10.1016/j.algal.2019.101713] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
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17
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Liefer JD, Garg A, Campbell DA, Irwin AJ, Finkel ZV. Correction: Nitrogen starvation induces distinct photosynthetic responses and recovery dynamics in diatoms and prasinophytes. PLoS One 2019; 14:e0224489. [PMID: 31652286 PMCID: PMC6814210 DOI: 10.1371/journal.pone.0224489] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
[This corrects the article DOI: 10.1371/journal.pone.0195705.].
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18
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Li W, Ding J, Li F, Wang T, Yang Y, Li Y, Campbell DA, Gao K. Functional responses of smaller and larger diatoms to gradual CO 2 rise. Sci Total Environ 2019; 680:79-90. [PMID: 31102831 DOI: 10.1016/j.scitotenv.2019.05.035] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/28/2019] [Revised: 04/27/2019] [Accepted: 05/03/2019] [Indexed: 06/09/2023]
Abstract
Diatoms and other phytoplankton groups are exposed to abrupt changes in pCO2, in waters in upwelling areas, near CO2 seeps, or during their blooms; or to more gradual pCO2 rise through anthropogenic CO2 emissions. Gradual CO2 rises have, however, rarely been included in ocean acidification (OA) studies. We therefore compared how small (Thalassiosira pseudonana) and larger (Thalassiosira weissflogii) diatom cell isolates respond to gradual pCO2 rises from 180 to 1000 μatm in steps of ~40 μatm with 5-10 generations at each step, and whether their responses to gradual pCO2 rise differ when compared to an abrupt pCO2 rise imposed from ambient 400 directly to 1000 μatm. Cell volume increased in T. pseudonana but decreased in T. weissflogii with an increase from low to moderate CO2 levels, and then remained steady under yet higher CO2 levels. Growth rates were stimulated, but Chl a, particulate organic carbon (POC) and cellular biogenic silica (BSi) decreased from low to moderate CO2 levels, and then remained steady with further CO2 rise in both species. Decreased saturation light intensity (Ik) and light use efficiency (α) with CO2 rise in T. pseudonana indicate that the smaller diatom becomes more susceptible to photoinhibition. Decreased BSi/POC (Si/C) in T. weissflogii indicates the biogeochemical cycles of both silicon and carbon may be more affected by elevated pCO2 in the larger diatom. The different CO2 modulation methods resulted in different responses of some key physiological parameters. Increasing pCO2 from 180 to 400 μatm decreased cellular POC and BSi contents, implying that ocean acidification to date has already altered diatom contributions to carbon and silicon biogeochemical processes.
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Affiliation(s)
- Wei Li
- State Key Laboratory of Marine Environmental Science, College of Ocean and Earth Sciences, Xiamen University, Xiamen 361102, China; College of Life and Environmental Sciences, Huangshan University, Huangshan 245041, China
| | - Jiancheng Ding
- State Key Laboratory of Marine Environmental Science, College of Ocean and Earth Sciences, Xiamen University, Xiamen 361102, China
| | - Futian Li
- State Key Laboratory of Marine Environmental Science, College of Ocean and Earth Sciences, Xiamen University, Xiamen 361102, China
| | - Tifeng Wang
- State Key Laboratory of Marine Environmental Science, College of Ocean and Earth Sciences, Xiamen University, Xiamen 361102, China
| | - Yuling Yang
- College of Life and Environmental Sciences, Huangshan University, Huangshan 245041, China
| | - Yahe Li
- State Key Laboratory of Marine Environmental Science, College of Ocean and Earth Sciences, Xiamen University, Xiamen 361102, China; School of Marine Sciences, Ningbo University, Ningbo 315211, Zhejiang, China
| | - Douglas A Campbell
- Biology Department, Mount Allison University, Sackville, NB E4L 1G7, Canada
| | - Kunshan Gao
- State Key Laboratory of Marine Environmental Science, College of Ocean and Earth Sciences, Xiamen University, Xiamen 361102, China; Laboratory for Marine Ecology and Environmental Science, Qingdao National Laboratory for Marine Science and Technology, Qingdao 266071, China.
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19
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Wang H, Zhang B, Song X, Jian X, Tang C, Campbell DA, Lin Q, Li G. High antioxidant capability interacts with respiration to mediate two Alexandrium species growth exploitation of photoperiods and light intensities. Harmful Algae 2019; 82:26-34. [PMID: 30928008 DOI: 10.1016/j.hal.2018.12.008] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/06/2018] [Revised: 12/26/2018] [Accepted: 12/26/2018] [Indexed: 06/09/2023]
Abstract
Light drives phytoplankton photosynthesis, so phytoplankton in their living habitats must exploit variable light levels and exposure durations, depending upon seasons, latitudes, depths and mixing events. Comparative growth, physiology and biochemical compositions were explored for the small Alexnadrium minutum (˜40 μm3 biovolume) and large Alexandrium catenella (˜9300 μm3 biovolume), globally wide spread coastal toxic red tide dinoflagellates, responding to a matrix of photoperiods (Light:Dark, 8:16, 16:8 and 24:0) and growth light irradiances. Smaller A. minutum grew faster under shorter photoperiods across growth light levels, while larger A. catenella grew fastest under longer photoperiods at the lowest applied light level. Photosystem II function responded largely to the instantaneous growth light level across photoperiod lengths, while the cell biovolume-based respiration, antioxidant capacity as well as cell composition responded more to photoperiod duration than to light level. These complex photophysiological responses resolved into linear correlations between growth rate versus cellular antioxidant activity and versus dark respiration, indicating that respiration energizes cellular antioxidant systems to benefit the growth of the cells. These results show the growth responses of Alexandrium species to light levels across photoperiods vary with species, and possibly with cell size. Together with previous results this puts a note of caution on meta-analytical extrapolations of physiological responses to light intensity derived from studies applying different photoperiods to different taxa, because different taxa show differential, even opposite growth responses to photoperiods and light intensities.
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Affiliation(s)
- Hui Wang
- Department of Biology, College of Sciences, Shantou University, Shantou 515063, Guangdong, China; STU-UNIVPM Joint Algal Research Center, College of Sciences, Shantou University, Shantou 515063, Guangdong, China
| | - Bowen Zhang
- Department of Biology, College of Sciences, Shantou University, Shantou 515063, Guangdong, China; STU-UNIVPM Joint Algal Research Center, College of Sciences, Shantou University, Shantou 515063, Guangdong, China
| | - Xingyu Song
- Key Laboratory of Tropical Marine Bio-Resources and Ecology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou 510530, China
| | - Xiaohui Jian
- Department of Biology, College of Sciences, Shantou University, Shantou 515063, Guangdong, China
| | - Chengxi Tang
- Department of Biology, College of Sciences, Shantou University, Shantou 515063, Guangdong, China
| | - Douglas A Campbell
- Department of Biology, Mount Allison University, Sackville NB, E4L 1G7, Canada
| | - Qiang Lin
- Key Laboratory of Tropical Marine Bio-Resources and Ecology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou 510530, China
| | - Gang Li
- Key Laboratory of Tropical Marine Bio-Resources and Ecology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou 510530, China.
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20
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Bonisteel EM, Turner BE, Murphy CD, Melanson JR, Duff NM, Beardsall BD, Xu K, Campbell DA, Cockshutt AM. Strain specific differences in rates of Photosystem II repair in picocyanobacteria correlate to differences in FtsH protein levels and isoform expression patterns. PLoS One 2018; 13:e0209115. [PMID: 30566504 PMCID: PMC6300248 DOI: 10.1371/journal.pone.0209115] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2018] [Accepted: 11/29/2018] [Indexed: 12/23/2022] Open
Abstract
Picocyanobacteria are the numerically dominant photoautotrophs of the oligotrophic regions of Earth’s oceans. These organisms are characterized by their small size and highly reduced genomes. Strains partition to different light intensity and nutrient level niches, with differing photosynthetic apparatus stoichiometry, light harvesting machinery and susceptibility to photoinactivation. In this study, we grew three strains of picocyanobacteria: the low light, high nutrient strain Prochlorococcus marinus MIT 9313; the high light, low nutrient Prochlorococcus marinus MED 4; and the high light, high nutrient marine Synechococcus strain WH 8102; under low and high growth light levels. We then performed matched photophysiology, protein and transcript analyses. The strains differ significantly in their rates of Photosystem II repair under high light and in their capacity to remove the PsbA protein as the first step in the Photosystem II repair process. Notably, all strains remove the PsbD subunit at the same rate that they remove PsbA. When grown under low light, MIT 9313 loses active Photosystem II quickly when shifted to high light, but has no measurable capacity to remove PsbA. MED 4 and WH 8102 show less rapid loss of Photosystem II and considerable capacity to remove PsbA. MIT 9313 has less of the FtsH protease thought to be responsible for the removal of PsbA in other cyanobacteria. Furthermore, by transcript analysis the predominant FtsH isoform expressed in MIT 9313 is homologous to the FtsH 4 isoform characterized in the model strain Synechocystis PCC 6803, rather than the FtsH 2 and 3 isoforms thought to be responsible for PsbA degradation. MED 4 on the other hand shows high light inducible expression of the isoforms homologous to FtsH 2 and 3, consistent with its faster rate of PsbA removal. MIT 9313 has adapted to its low light environment by diverting resources away from Photosystem II content and repair.
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Affiliation(s)
- Erin M. Bonisteel
- Department of Chemistry & Biochemistry, Mount Allison University, Sackville, New Brunswick, Canada
| | - Brooke E. Turner
- Department of Chemistry & Biochemistry, Mount Allison University, Sackville, New Brunswick, Canada
| | - Cole D. Murphy
- Department of Chemistry & Biochemistry, Mount Allison University, Sackville, New Brunswick, Canada
| | - Jenna-Rose Melanson
- Department of Chemistry & Biochemistry, Mount Allison University, Sackville, New Brunswick, Canada
| | - Nicole M. Duff
- Department of Biology, Mount Allison University, Sackville, New Brunswick, Canada
| | - Brian D. Beardsall
- Department of Chemistry & Biochemistry, Mount Allison University, Sackville, New Brunswick, Canada
| | - Kui Xu
- Department of Biology, Mount Allison University, Sackville, New Brunswick, Canada
- Environmental Microbiomics Research Center, School of Environmental Science and Engineering, Sun Yat-sen University, Guangzhou, China
| | - Douglas A. Campbell
- Department of Biology, Mount Allison University, Sackville, New Brunswick, Canada
| | - Amanda M. Cockshutt
- Department of Chemistry & Biochemistry, Mount Allison University, Sackville, New Brunswick, Canada
- * E-mail:
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21
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Hughes DJ, Campbell DA, Doblin MA, Kromkamp JC, Lawrenz E, Moore CM, Oxborough K, Prášil O, Ralph PJ, Alvarez MF, Suggett DJ. Roadmaps and Detours: Active Chlorophyll- a Assessments of Primary Productivity Across Marine and Freshwater Systems. Environ Sci Technol 2018; 52:12039-12054. [PMID: 30247887 DOI: 10.1021/acs.est.8b03488] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Assessing phytoplankton productivity over space and time remains a core goal for oceanographers and limnologists. Fast Repetition Rate fluorometry (FRRf) provides a potential means to realize this goal with unprecedented resolution and scale yet has not become the "go-to" method despite high expectations. A major obstacle is difficulty converting electron transfer rates to equivalent rates of C-fixation most relevant for studies of biogeochemical C-fluxes. Such difficulty stems from methodological inconsistencies and our limited understanding of how the electron requirement for C-fixation (Φe,C) is influenced by the environment and by differences in the composition and physiology of phytoplankton assemblages. We outline a "roadmap" for limiting methodological bias and to develop a more mechanistic understanding of the ecophysiology underlying Φe,C. We 1) re-evaluate core physiological processes governing how microalgae invest photosynthetic electron transport-derived energy and reductant into stored carbon versus alternative sinks. Then, we 2) outline steps to facilitate broader uptake and exploitation of FRRf, which could transform our knowledge of aquatic primary productivity. We argue it is time to 3) revise our historic methodological focus on carbon as the currency of choice, to 4) better appreciate that electron transport fundamentally drives ecosystem biogeochemistry, modulates cell-to-cell interactions, and ultimately modifies community biomass and structure.
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Affiliation(s)
- David J Hughes
- Climate Change Cluster , University of Technology Sydney , Ultimo, Sydney 2007 , New South Wales , Australia
| | - Douglas A Campbell
- Department of Biology , Mount Allison University , Sackville , New Brunswick E4L 1E4 , Canada
| | - Martina A Doblin
- Climate Change Cluster , University of Technology Sydney , Ultimo, Sydney 2007 , New South Wales , Australia
| | - Jacco C Kromkamp
- Department of Estuarine and Delta Systems , NIOZ Royal Netherlands Institute for Sea Research and Utrecht University , P.O. Box 140, 4401 NT Yerseke , The Netherlands
| | - Evelyn Lawrenz
- Centre Algatech , Institute of Microbiology, Czech Academy of Sciences , Třeboň 379 81 , Czech Republic
| | - C Mark Moore
- Ocean and Earth Science , University of Southampton, National Oceanography Centre, Southampton , European Way , Southampton SO14 3ZH , U.K
| | | | - Ondřej Prášil
- Centre Algatech , Institute of Microbiology, Czech Academy of Sciences , Třeboň 379 81 , Czech Republic
| | - Peter J Ralph
- Climate Change Cluster , University of Technology Sydney , Ultimo, Sydney 2007 , New South Wales , Australia
| | - Marco F Alvarez
- Climate Change Cluster , University of Technology Sydney , Ultimo, Sydney 2007 , New South Wales , Australia
| | - David J Suggett
- Climate Change Cluster , University of Technology Sydney , Ultimo, Sydney 2007 , New South Wales , Australia
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Perkins R, Williamson C, Lavaud J, Mouget JL, Campbell DA. Time-dependent upregulation of electron transport with concomitant induction of regulated excitation dissipation in Haslea diatoms. Photosynth Res 2018; 137:377-388. [PMID: 29663190 PMCID: PMC6182385 DOI: 10.1007/s11120-018-0508-x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/18/2017] [Accepted: 04/11/2018] [Indexed: 06/01/2023]
Abstract
Photoacclimation by strains of Haslea "blue" diatom species H. ostrearia and H. silbo sp. nov. ined. was investigated with rapid light curves and induction-recovery curves using fast repetition rate fluorescence. Cultures were grown to exponential phase under 50 µmol m-2 s-1 photosynthetic available radiation (PAR) and then exposed to non-sequential rapid light curves where, once electron transport rate (ETR) had reached saturation, light intensity was decreased and then further increased prior to returning to near growth light intensity. The non-sequential rapid light curve revealed that ETR was not proportional to the instantaneously applied light intensity, due to rapid photoacclimation. Changes in the effective absorption cross sections for open PSII reaction centres (σPSII') or reaction centre connectivity (ρ) did not account for the observed increases in ETR under extended high light. σPSII' in fact decreased as a function of a time-dependent induction of regulated excitation dissipation Y(NPQ), once cells were at or above a PAR coinciding with saturation of ETR. Instead, the observed increases in ETR under extended high light were explained by an increase in the rate of PSII reopening, i.e. QA- oxidation. This acceleration of electron transport was strictly light dependent and relaxed within seconds after a return to low light or darkness. The time-dependent nature of ETR upregulation and regulated NPQ induction was verified using induction-recovery curves. Our findings show a time-dependent induction of excitation dissipation, in parallel with very rapid photoacclimation of electron transport, which combine to make ETR independent of short-term changes in PAR. This supports a selective advantage for these diatoms when exposed to fluctuating light in their environment.
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Affiliation(s)
- R Perkins
- School of Earth and Ocean Sciences, Cardiff University, Park Place, Cardiff, Wales, CF10 3AT, UK.
| | - C Williamson
- School of Earth and Ocean Sciences, Cardiff University, Park Place, Cardiff, Wales, CF10 3AT, UK
- Schools of Biological and Geographical Sciences, University of Bristol, 12 Berkeley Square, Bristol, BS8 1SS, UK
| | - J Lavaud
- UMI 3376 Takuvik, CNRS/Université Laval, Département de Biologie-Pavillon Alexandre Vachon, Québec, QC, G1V 0A6, Canada
| | - J-L Mouget
- Mer-Molécules-Santé (MMS), FR CNRS 3473 IUML, Le Mans Université, Av. O. Messiaen, 72085, Le Mans Cedex 9, France
| | - D A Campbell
- Department of Biology, Mount Allison University, Sackville, NB, E4L3M7, Canada
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Blanco-Ameijeiras S, Moisset SAM, Trimborn S, Campbell DA, Heiden JP, Hassler CS. Elemental Stoichiometry and Photophysiology Regulation of Synechococcus sp. PCC7002 Under Increasing Severity of Chronic Iron Limitation. Plant Cell Physiol 2018; 59:1803-1816. [PMID: 29860486 DOI: 10.1093/pcp/pcy097] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/15/2017] [Accepted: 05/11/2018] [Indexed: 06/08/2023]
Abstract
Iron (Fe) is an essential cofactor for many metabolic enzymes of photoautotrophs. Although Fe limits phytoplankton productivity in broad areas of the ocean, phytoplankton have adapted their metabolism and growth to survive in these conditions. Using the euryhaline cyanobacterium Synechococcus sp. PCC7002, we investigated the physiological responses to long-term acclimation to four levels of Fe availability representative of the contemporary ocean (36.7, 3.83, 0.47 and 0.047 pM Fe'). With increasing severity of Fe limitation, Synechococcus sp. cells gradually decreased their volume and growth while increasing their energy allocation into organic carbon and nitrogen cellular pools. Furthermore, the total cellular content of pigments decreased. Additionally, with increasing severity of Fe limitation, intertwined responses of PSII functional cross-section (σPSII), re-oxidation time of the plastoquinone primary acceptor QA (τ) and non-photochemical quenching revealed a shift in the photophysiological response between mild to strong Fe limitation compared with severe limitation. Under mild and strong Fe limitation, there was a decrease in linear electron transport accompanied by progressive loss of state transitions. Under severe Fe limitation, state transitions seemed to be largely supplanted by alternative electron pathways. In addition, mechanisms to dissipate energy excess and minimize oxidative stress associated with high irradiances increased with increasing severity of Fe limitation. Overall, our results establish the sequence of physiological strategies adopted by the cells under increasing severity of chronic Fe limitation, within a range of Fe concentrations relevant to modern ocean biogeochemistry.
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Affiliation(s)
- Sonia Blanco-Ameijeiras
- Department F.-A. Forel for Environmental and Aquatic Sciences, Faculty of Science, University of Geneva, Boulevard Carl-Vogt 66, Geneva 4, Switzerland
| | - Sophie A M Moisset
- Department F.-A. Forel for Environmental and Aquatic Sciences, Faculty of Science, University of Geneva, Boulevard Carl-Vogt 66, Geneva 4, Switzerland
| | - Scarlett Trimborn
- Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research, Am Handelshafen 12, Bremerhaven, Germany
- Marine Botany, University of Bremen, Leobener Strasse NW2-A, Bremen, Germany
| | - Douglas A Campbell
- Biology, Faculty of Science, Mount Allison University, Sackville, NB, Canada
| | - Jasmin P Heiden
- Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research, Am Handelshafen 12, Bremerhaven, Germany
- Marine Botany, University of Bremen, Leobener Strasse NW2-A, Bremen, Germany
| | - Christel S Hassler
- Department F.-A. Forel for Environmental and Aquatic Sciences, Faculty of Science, University of Geneva, Boulevard Carl-Vogt 66, Geneva 4, Switzerland
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Bannon CC, Campbell DA. Correction: Sinking towards destiny: High throughput measurement of phytoplankton sinking rates through time-resolved fluorescence plate spectroscopy. PLoS One 2018; 13:e0196624. [PMID: 29689103 PMCID: PMC5915776 DOI: 10.1371/journal.pone.0196624] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/03/2022] Open
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Liefer JD, Garg A, Campbell DA, Irwin AJ, Finkel ZV. Nitrogen starvation induces distinct photosynthetic responses and recovery dynamics in diatoms and prasinophytes. PLoS One 2018; 13:e0195705. [PMID: 29641594 PMCID: PMC5895044 DOI: 10.1371/journal.pone.0195705] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2017] [Accepted: 03/28/2018] [Indexed: 11/18/2022] Open
Abstract
Nitrogen stress is an important control on the growth of phytoplankton and varying responses to this common condition among taxa may affect their relative success within phytoplankton communities. We analyzed photosynthetic responses to nitrogen (N) stress in two classes of phytoplankton that often dominate their respective size ranges, diatoms and prasinophytes, selecting species of distinct niches within each class. Changes in photosynthetic structures appeared similar within each class during N stress, but photophysiological and growth responses were more species- or niche-specific. In the coastal diatom Thalassiosira pseudonana and the oceanic diatom T. weissflogii, N starvation induced large declines in photosynthetic pigments and Photosystem II (PSII) quantity and activity as well as increases in the effective absorption cross-section of PSII photochemistry (σ'PSII). These diatoms also increased photoprotection through energy-dependent non-photochemical quenching (NPQ) during N starvation. Resupply of N in diatoms caused rapid recovery of growth and relaxation of NPQ, while recovery of PSII photochemistry was slower. In contrast, the prasinophytes Micromonas sp., an Arctic Ocean species, and Ostreococcus tauri, a temperate coastal eutrophile, showed little change in photosynthetic pigments and structures and a decline or no change, respectively, in σ'PSII with N starvation. Growth and PSII function recovered quickly in Micromonas sp. after resupply of N while O. tauri failed to recover N-replete levels of electron transfer from PSII and growth, possibly due to their distinct photoprotective strategies. O. tauri induced energy-dependent NPQ for photoprotection that may suit its variable and nutrient-rich habitat. Micromonas sp. relies upon both energy-dependent NPQ and a sustained, energy-independent NPQ mechanism. A strategy in Micromonas sp. that permits photoprotection with little change in photosynthetic structures is consistent with its Arctic niche, where low temperatures and thus low biosynthetic rates create higher opportunity costs to rebuild photosynthetic structures.
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Affiliation(s)
- Justin D. Liefer
- Department of Geography and Environment, Mount Allison University, Sackville, New Brunswick, Canada
- * E-mail:
| | - Aneri Garg
- Department of Geography and Environment, Mount Allison University, Sackville, New Brunswick, Canada
| | - Douglas A. Campbell
- Department of Biology, Mount Allison University, Sackville, New Brunswick, Canada
| | - Andrew J. Irwin
- Department of Mathematics and Computer Science, Mount Allison University, Sackville, New Brunswick, Canada
| | - Zoe V. Finkel
- Department of Geography and Environment, Mount Allison University, Sackville, New Brunswick, Canada
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Ni G, Zimbalatti G, Murphy CD, Barnett AB, Arsenault CM, Li G, Cockshutt AM, Campbell DA. Correction to: Arctic Micromonas uses protein pools and non-photochemical quenching to cope with temperature restrictions on Photosystem II protein turnover. Photosynth Res 2018; 136:127. [PMID: 29256108 PMCID: PMC6828251 DOI: 10.1007/s11120-017-0471-y] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
In Table 2 of the original publication, all instances of krec in the Parameter and Equation columns should read krecinact.
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Affiliation(s)
- Guangyan Ni
- Department of Chemistry & Biochemistry, Mount Allison University, 63B York St., Sackville, NB, E4L3M7, Canada
- Key Laboratory of Vegetation Restoration and Management of Degraded Ecosystems, South China Botanical Garden, CAS, Guangzhou, 510160, China
| | - Gabrielle Zimbalatti
- Department of Chemistry & Biochemistry, Mount Allison University, 63B York St., Sackville, NB, E4L3M7, Canada
| | - Cole D Murphy
- Department of Chemistry & Biochemistry, Mount Allison University, 63B York St., Sackville, NB, E4L3M7, Canada
| | | | - Christopher M Arsenault
- Department of Chemistry & Biochemistry, Mount Allison University, 63B York St., Sackville, NB, E4L3M7, Canada
| | - Gang Li
- Department of Chemistry & Biochemistry, Mount Allison University, 63B York St., Sackville, NB, E4L3M7, Canada
- Key Laboratory of Tropical Marine Bio-resources and Ecology, South China Sea Institute of Oceanology, CAS, Guangzhou, 510301, China
| | - Amanda M Cockshutt
- Department of Chemistry & Biochemistry, Mount Allison University, 63B York St., Sackville, NB, E4L3M7, Canada
| | - Douglas A Campbell
- Department of Chemistry & Biochemistry, Mount Allison University, 63B York St., Sackville, NB, E4L3M7, Canada.
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Bannon CC, Campbell DA. Sinking towards destiny: High throughput measurement of phytoplankton sinking rates through time-resolved fluorescence plate spectroscopy. PLoS One 2017; 12:e0185166. [PMID: 28972987 PMCID: PMC5626032 DOI: 10.1371/journal.pone.0185166] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2017] [Accepted: 09/07/2017] [Indexed: 12/30/2022] Open
Abstract
Diatoms are marine primary producers that sink in part due to the density of their silica frustules. Sinking of these phytoplankters is crucial for both the biological pump that sequesters carbon to the deep ocean and for the life strategy of the organism. Sinking rates have been previously measured through settling columns, or with fluorimeters or video microscopy arranged perpendicularly to the direction of sinking. These side-view techniques require large volumes of culture, specialized equipment and are difficult to scale up to multiple simultaneous measures for screening. We established a method for parallel, large scale analysis of multiple phytoplankton sinking rates through top-view monitoring of chlorophyll a fluorescence in microtitre well plates. We verified the method through experimental analysis of known factors that influence sinking rates, including exponential versus stationary growth phase in species of different cell sizes; Thalassiosira pseudonana CCMP1335, chain-forming Skeletonema marinoi RO5A and Coscinodiscus radiatus CCMP312. We fit decay curves to an algebraic transform of the decrease in fluorescence signal as cells sank away from the fluorometer detector, and then used minimal mechanistic assumptions to extract a sinking rate (m d-1) using an RStudio script, SinkWORX. We thereby detected significant differences in sinking rates as larger diatom cells sank faster than smaller cells, and cultures in stationary phase sank faster than those in exponential phase. Our sinking rate estimates accord well with literature values from previously established methods. This well plate-based method can operate as a high throughput integrative phenotypic screen for factors that influence sinking rates including macromolecular allocations, nutrient availability or uptake rates, chain-length or cell size, degree of silification and progression through growth stages. Alternately the approach can be used to phenomically screen libraries of mutants.
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Affiliation(s)
| | - Douglas A. Campbell
- Biology Department, Mount Allison University, Sackville, NB, Canada
- * E-mail:
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Wu Y, Campbell DA, Gao K. Short-term elevated CO 2 exposure stimulated photochemical performance of a coastal marine diatom. Mar Environ Res 2017; 125:42-48. [PMID: 28126512 DOI: 10.1016/j.marenvres.2016.12.001] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/01/2016] [Revised: 12/07/2016] [Accepted: 12/12/2016] [Indexed: 06/06/2023]
Abstract
Ocean acidification changes seawater chemistry, with increased CO2 and decreased pH regarded as the most important factors that impact marine organisms. This study employed an unconventional methodology to distinguish the independent effects of pH versus CO2. Changes in CO2 dominated the photochemical responses of the coastal diatom Phaeodactylum tricornutum to short-term ocean acidification. Increased CO2 lowered non-photochemical quenching of excitation and stimulated the electron transport rates of photosynthesis, with the largest effects on both parameters when CO2 and pH were altered simultaneously. Changes in pH alone did not show significant effects upon non-photochemical quenching (NPQ) nor upon electron transport rates, but can synergistically amplify CO2 effects under low light. Maximal induction of NPQ after illumination showed only a limited response to increasing CO2 under stable pH, across a range of increasing light levels, but maximal induced NPQ declined rapidly with increasing CO2 under variable pH, when measured under exposure to sub-saturating light, but not under saturating light. These findings show that aqueous CO2 and pH affect different physiological processes independently or interactively, which should be taken into account in future research for better understanding of responses to ocean acidification at the mechanistic level.
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Affiliation(s)
- Yaping Wu
- State Key Laboratory of Marine Environmental Science, Xiamen University, Xiamen, China
| | - Douglas A Campbell
- Biology Department, Mount Allison University, Sackville, New Brunswick, Canada
| | - Kunshan Gao
- State Key Laboratory of Marine Environmental Science, Xiamen University, Xiamen, China.
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29
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Li G, Talmy D, Campbell DA. Diatom growth responses to photoperiod and light are predictable from diel reductant generation. J Phycol 2017; 53:95-107. [PMID: 27754547 PMCID: PMC5363399 DOI: 10.1111/jpy.12483] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/10/2016] [Accepted: 09/13/2016] [Indexed: 05/11/2023]
Abstract
Light drives phytoplankton productivity, so phytoplankton must exploit variable intensities and durations of light exposure, depending upon season, latitude, and depth. We analyzed the growth, photophysiology and composition of small, Thalassiosira pseudonana, and large, Thalassiosira punctigera, centric diatoms from temperate, coastal marine habitats, responding to a matrix of photoperiods and growth light intensities. T. pseudonana showed fastest growth rates under long photoperiods and low to moderate light intensities, while the larger T. punctigera showed fastest growth rates under short photoperiods and higher light intensities. Photosystem II function and content responded primarily to instantaneous growth light intensities during the photoperiod, while diel carbon fixation and RUBISCO content responded more to photoperiod duration than to instantaneous light intensity. Changing photoperiods caused species-specific changes in the responses of photochemical yield (e- /photon) to growth light intensity. These photophysiological variables showed complex responses to photoperiod and to growth light intensity. Growth rate also showed complex responses to photoperiod and growth light intensity. But these complex responses resolved into a close relation between growth rate and the cumulative daily generation of reductant, across the matrix of photoperiods and light intensities.
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Affiliation(s)
- Gang Li
- Key Laboratory of Tropical Marine Bio-resources and Ecology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, China
| | - David Talmy
- Department of Earth, Atmosphere and Planetary Sciences, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts, 02139, USA
| | - Douglas A Campbell
- Department of Biology, Mount Allison University, 63B York St., Sackville, New Brunswick, Canada
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30
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Ni G, Zimbalatti G, Murphy CD, Barnett AB, Arsenault CM, Li G, Cockshutt AM, Campbell DA. Arctic Micromonas uses protein pools and non-photochemical quenching to cope with temperature restrictions on Photosystem II protein turnover. Photosynth Res 2017; 131:203-220. [PMID: 27639727 PMCID: PMC5247552 DOI: 10.1007/s11120-016-0310-6] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/28/2016] [Accepted: 09/08/2016] [Indexed: 05/12/2023]
Abstract
Micromonas strains of small prasinophyte green algae are found throughout the world's oceans, exploiting widely different niches. We grew arctic and temperate strains of Micromonas and compared their susceptibilities to photoinactivation of Photosystem II, their counteracting Photosystem II repair capacities, their Photosystem II content, and their induction and relaxation of non-photochemical quenching. In the arctic strain Micromonas NCMA 2099, the cellular content of active Photosystem II represents only about 50 % of total Photosystem II protein, as a slow rate constant for clearance of PsbA protein limits instantaneous repair. In contrast, the temperate strain NCMA 1646 shows a faster clearance of PsbA protein which allows it to maintain active Photosystem II content equivalent to total Photosystem II protein. Under growth at 2 °C, the arctic Micromonas maintains a constitutive induction of xanthophyll deepoxidation, shown by second-derivative whole-cell spectra, which supports strong induction of non-photochemical quenching under low to moderate light, even if xanthophyll cycling is blocked. This non-photochemical quenching, however, relaxes during subsequent darkness with kinetics nearly comparable to the temperate Micromonas NCMA 1646, thereby limiting the opportunity cost of sustained downregulation of PSII function after a decrease in light.
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Affiliation(s)
- Guangyan Ni
- Department of Chemistry & Biochemistry, Mount Allison University, 63B York St., Sackville, NB, E4L3M7, Canada
- Key Laboratory of Vegetation Restoration and Management of Degraded Ecosystems, South China Botanical Garden, CAS, Guangzhou, 510160, China
| | - Gabrielle Zimbalatti
- Department of Chemistry & Biochemistry, Mount Allison University, 63B York St., Sackville, NB, E4L3M7, Canada
| | - Cole D Murphy
- Department of Chemistry & Biochemistry, Mount Allison University, 63B York St., Sackville, NB, E4L3M7, Canada
| | | | - Christopher M Arsenault
- Department of Chemistry & Biochemistry, Mount Allison University, 63B York St., Sackville, NB, E4L3M7, Canada
| | - Gang Li
- Department of Chemistry & Biochemistry, Mount Allison University, 63B York St., Sackville, NB, E4L3M7, Canada
- Key Laboratory of Tropical Marine Bio-resources and Ecology, South China Sea Institute of Oceanology, CAS, Guangzhou, 510301, China
| | - Amanda M Cockshutt
- Department of Chemistry & Biochemistry, Mount Allison University, 63B York St., Sackville, NB, E4L3M7, Canada
| | - Douglas A Campbell
- Department of Chemistry & Biochemistry, Mount Allison University, 63B York St., Sackville, NB, E4L3M7, Canada.
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Murphy CD, Roodvoets MS, Austen EJ, Dolan A, Barnett A, Campbell DA. Photoinactivation of Photosystem II in Prochlorococcus and Synechococcus. PLoS One 2017; 12:e0168991. [PMID: 28129341 PMCID: PMC5271679 DOI: 10.1371/journal.pone.0168991] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2016] [Accepted: 12/10/2016] [Indexed: 01/15/2023] Open
Abstract
The marine picocyanobacteria Synechococcus and Prochlorococcus numerically dominate open ocean phytoplankton. Although evolutionarily related they are ecologically distinct, with different strategies to harvest, manage and exploit light. We grew representative strains of Synechococcus and Prochlorococcus and tracked their susceptibility to photoinactivation of Photosystem II under a range of light levels. As expected blue light provoked more rapid photoinactivation than did an equivalent level of red light. The previous growth light level altered the susceptibility of Synechococcus, but not Prochlorococcus, to this photoinactivation. We resolved a simple linear pattern when we expressed the yield of photoinactivation on the basis of photons delivered to Photosystem II photochemistry, plotted versus excitation pressure upon Photosystem II, the balance between excitation and downstream metabolism. A high excitation pressure increases the generation of reactive oxygen species, and thus increases the yield of photoinactivation of Photosystem II. Blue photons, however, retained a higher baseline photoinactivation across a wide range of excitation pressures. Our experiments thus uncovered the relative influences of the direct photoinactivation of Photosystem II by blue photons which dominates under low to moderate blue light, and photoinactivation as a side effect of reactive oxygen species which dominates under higher excitation pressure. Synechococcus enjoyed a positive metabolic return upon the repair or the synthesis of a Photosystem II, across the range of light levels we tested. In contrast Prochlorococcus only enjoyed a positive return upon synthesis of a Photosystem II up to 400 μmol photons m-2 s-1. These differential cost-benefits probably underlie the distinct photoacclimation strategies of the species.
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Affiliation(s)
- Cole D. Murphy
- Biochemistry and Chemistry, Mount Allison University, Sackville, New Brunswick, Canada
| | - Mitchell S. Roodvoets
- Biochemistry and Chemistry, Mount Allison University, Sackville, New Brunswick, Canada
| | - Emily J. Austen
- Biology, Mount Allison University, Sackville, New Brunswick, Canada
| | - Allison Dolan
- Biology, Mount Allison University, Sackville, New Brunswick, Canada
| | - Audrey Barnett
- Michigan Technological University, Houghton, Michigan, United States of America
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Li G, Campbell DA. Interactive effects of nitrogen and light on growth rates and RUBISCO content of small and large centric diatoms. Photosynth Res 2017; 131:93-103. [PMID: 27566625 PMCID: PMC5167766 DOI: 10.1007/s11120-016-0301-7] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/01/2016] [Accepted: 08/17/2016] [Indexed: 05/31/2023]
Abstract
Among marine phytoplankton groups, diatoms span the widest range of cell size, with resulting effects upon their nitrogen uptake, photosynthesis and growth responses to light. We grew two strains of marine centric diatoms differing by ~4 orders of magnitude in cell biovolume in high (enriched artificial seawater with ~500 µmol L-1 µmol L-1 NO3-) and lower-nitrogen (enriched artificial seawater with <10 µmol L-1 NO3-) media, across a range of growth light levels. Nitrogen and total protein per cell decreased with increasing growth light in both species when grown under the lower-nitrogen media. Cells growing under lower-nitrogen media increased their cellular allocation to RUBISCO and their rate of electron transport away from PSII, for the smaller diatom under low growth light and for the larger diatom across the range of growth lights. The smaller coastal diatom Thalassiosira pseudonana is able to exploit high nitrogen in growth media by up-regulating growth rate, but the same high-nitrogen growth media inhibits growth of the larger diatom species.
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Affiliation(s)
- Gang Li
- Biology Department, Mount Allison University, Sackville, NB, E4L 1G7, Canada
- Key Laboratory of Tropical Marine Bio-Resources and Ecology, South China Sea Institute of Oceanology, CAS, Guangzhou, 510301, China
| | - Douglas A Campbell
- Biology Department, Mount Allison University, Sackville, NB, E4L 1G7, Canada.
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Till SR, Edwards M, Kobernik E, Kamdar N, As-Sanie S, Campbell DA, Morgan DM. Implementation Rate of Risk-Reducing Salpingectomy at Time of Benign Hysterectomy. J Minim Invasive Gynecol 2016. [DOI: 10.1016/j.jmig.2016.08.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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Abstract
This is the second half of a story begun in the article “What's Wrong With Doug: The Academic Struggles of a Gifted Student With ADHD from Preschool to College” published in Fall 2002.
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Lavaud J, Six C, Campbell DA. Photosystem II repair in marine diatoms with contrasting photophysiologies. Photosynth Res 2016; 127:189-99. [PMID: 26156125 DOI: 10.1007/s11120-015-0172-3] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/18/2015] [Accepted: 06/25/2015] [Indexed: 05/23/2023]
Abstract
Skeletonema costatum and Phaeodactylum tricornutum are model marine diatoms with differing strategies for non-photochemical dissipation of excess excitation energy within photosystem II (PSII). We showed that S. costatum, with connectivity across the pigment bed serving PSII, and limited capacity for induction of sustained non-photochemical quenching (NPQ), maintained a large ratio of [PSII(Total)]/[PSII(Active)] to buffer against fluctuations in light intensity. In contrast, P. tricornutum, with a larger capacity to induce sustained NPQ, could maintain a lower [PSII(Total)]/[PSII(Active)]. Induction of NPQ was correlated with an active PSII repair cycle in both species, and inhibition of chloroplastic protein synthesis with lincomycin leads to run away over-excitation of remaining PSII(Active), particularly in S. costatum. We discuss these distinctions in relation to the differing capacities, induction and relaxation rates for NPQ, and as strain adaptations to the differential light regimes of their originating habitats. The present work further confirms the important role for the light-dependent fast regulation of photochemistry by NPQ interacting with PSII repair cycle capacity in the ecophysiology of both pennate and centric diatoms.
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Affiliation(s)
- Johann Lavaud
- UMRi 7266 'LIENSs', Institut du Littoral et de l'Environnement (ILE), CNRS-University of La Rochelle, 2 rue Olympe de Gouges, 17000, La Rochelle Cedex, France.
| | - Christophe Six
- Department of Biology, Mount Allison University, Sackville, NB E4L 1G7, Canada
- UMR 7144 'Adaptation et Diversité en Milieu Marin', 'Marine Phototrophic Prokaryotes' group, Centre National pour la Recherche Scientifique (CNRS), Station Biologique de Roscoff, Place George Teissier, 29680, Roscoff, France
- UMR 7144 'Adaptation et Diversité en Milieu Marin', 'Marine Phototrophic Prokaryotes' group, Université Pierre et Marie Curie (Paris 06), Station Biologique de Roscoff, Place George Teissier, 29680, Roscoff, France
| | - Douglas A Campbell
- Department of Biology, Mount Allison University, Sackville, NB E4L 1G7, Canada
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Vandenhecke JMR, Bastedo J, Cockshutt AM, Campbell DA, Huot Y. Changes in the Rubisco to photosystem ratio dominates photoacclimation across phytoplankton taxa. Photosynth Res 2015; 124:275-291. [PMID: 25862645 DOI: 10.1007/s11120-015-0137-6] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/02/2014] [Accepted: 03/31/2015] [Indexed: 06/04/2023]
Abstract
When growth irradiance changes, phytoplankton acclimates by changing allocations to cellular components to re-balance their capacity to absorb photons versus their capacity to use the electrons from the oxidation of water at photosystem II. Published changes in the cellular allocations resulting from photoacclimation across algal groups highlight that algae adopt different strategies. We examined the photoacclimation of the photosynthetic apparatus of six marine phytoplankters under near-natural diel irradiance patterns. For most of the phytoplankters, Chl a per structural photosystem II unit decreased with increasing growth irradiance, but a parallel decline in optical packaging effect allowed cells to maintain their functional absorption cross section serving active photosystem II units (σ PSII). Furthermore, no significant changes were observed in the ratio of Chl a per photosystem I. The diatom Skeletonema marinoi proved an exception to this pattern as Chl a per photosystem II is stable and Chl a per photosystem I slightly decreased with light intensity. A clear decrease in the photosystem content per cell was observed for all species except for Thalassiosira oceanica and S. marinoi. Rubisco content per cell showed little variation with irradiance for most algae, except for a 3-fold increase in S. marinoi. A ~700 % increase in the Rubisco:photosystem ratio across species with increasing growth irradiance indicates this is a key cellular stoichiometric adjustment to balance photon absorption capacity and the carbon reduction capacity. Increasing the Rubisco:photosystem ratio occurs through a decrease in the photosystems per cell for most of the phytoplankters in this study, except in the case of S. marinoi where Rubisco per cell increased.
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Affiliation(s)
- Jennifer Marie-Rose Vandenhecke
- Canada Research Chair in Earth Observation and Phytoplankton Ecophysiology, Université de Sherbrooke, Sherbrooke, QC, J1K 2R1, Canada,
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Cai X, Gao K, Fu F, Campbell DA, Beardall J, Hutchins DA. Electron transport kinetics in the diazotrophic cyanobacterium Trichodesmium spp. grown across a range of light levels. Photosynth Res 2015; 124:45-56. [PMID: 25616859 DOI: 10.1007/s11120-015-0081-5] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/14/2014] [Accepted: 01/06/2015] [Indexed: 05/13/2023]
Abstract
The diazotrophic cyanobacterium Trichodesmium is a major contributor to marine nitrogen fixation. We analyzed how light acclimation influences the photophysiological performance of Trichodesmium IMS101 during exponential growth in semi-continuous nitrogen fixing cultures under light levels of 70, 150, 250, and 400 μmol photons m(-2) s(-1), across diel cycles. There were close correlations between growth rate, trichome length, particulate organic carbon and nitrogen assimilation, and cellular absorbance, which all peaked at 150 μmol photons m(-2) s(-1). Growth rate was light saturated by about 100 μmol photons m(-2) s(-1) and was photoinhibited above 150 μmol photons m(-2) s(-1). In contrast, the light level (I k) to saturate PSII electron transport (e (-) PSII(-1) s(-1)) was much higher, in the range of 450-550 μmol photons m(-2) s(-1), and increased with growth light. Growth rate correlates with the absorption cross section as well as with absorbed photons per cell, but not to electron transport per PSII; this disparity suggests that numbers of PSII in a cell, along with the energy allocation between two photosystems and the state transition mechanism underlie the changes in growth rates. The rate of state transitions after a transfer to darkness increased with growth light, indicating faster respiratory input into the intersystem electron transport chain.
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Affiliation(s)
- Xiaoni Cai
- State Key Laboratory of Marine Environmental Science, Xiamen University, Xiamen, Fujian, China
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Zorz JK, Allanach JR, Murphy CD, Roodvoets MS, Campbell DA, Cockshutt AM. The RUBISCO to Photosystem II Ratio Limits the Maximum Photosynthetic Rate in Picocyanobacteria. Life (Basel) 2015; 5:403-17. [PMID: 25658887 PMCID: PMC4390859 DOI: 10.3390/life5010403] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2014] [Revised: 01/12/2015] [Accepted: 01/22/2015] [Indexed: 01/22/2023] Open
Abstract
Marine Synechococcus and Prochlorococcus are picocyanobacteria predominating in subtropical, oligotrophic marine environments, a niche predicted to expand with climate change. When grown under common low light conditions Synechococcus WH 8102 and Prochlorococcus MED 4 show similar Cytochrome b6f and Photosystem I contents normalized to Photosystem II content, while Prochlorococcus MIT 9313 has twice the Cytochrome b6f content and four times the Photosystem I content of the other strains. Interestingly, the Prochlorococcus strains contain only one third to one half of the RUBISCO catalytic subunits compared to the marine Synechococcus strain. The maximum Photosystem II electron transport rates were similar for the two Prochlorococcus strains but higher for the marine Synechococcus strain. Photosystem II electron transport capacity is highly correlated to the molar ratio of RUBISCO active sites to Photosystem II but not to the ratio of cytochrome b6f to Photosystem II, nor to the ratio of Photosystem I: Photosystem II. Thus, the catalytic capacity for the rate-limiting step of carbon fixation, the ultimate electron sink, appears to limit electron transport rates. The high abundance of Cytochrome b6f and Photosystem I in MIT 9313, combined with the slower flow of electrons away from Photosystem II and the relatively low level of RUBISCO, are consistent with cyclic electron flow around Photosystem I in this strain.
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Affiliation(s)
- Jackie K Zorz
- Department of Chemistry & Biochemistry, Mount Allison University, Sackville, New Brunswick, E4L 1G8, Canada.
| | - Jessica R Allanach
- Department of Chemistry & Biochemistry, Mount Allison University, Sackville, New Brunswick, E4L 1G8, Canada.
| | - Cole D Murphy
- Department of Chemistry & Biochemistry, Mount Allison University, Sackville, New Brunswick, E4L 1G8, Canada.
| | - Mitchell S Roodvoets
- Department of Chemistry & Biochemistry, Mount Allison University, Sackville, New Brunswick, E4L 1G8, Canada.
| | - Douglas A Campbell
- Department of Chemistry & Biochemistry, Mount Allison University, Sackville, New Brunswick, E4L 1G8, Canada.
| | - Amanda M Cockshutt
- Department of Chemistry & Biochemistry, Mount Allison University, Sackville, New Brunswick, E4L 1G8, Canada.
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Li G, Brown CM, Jeans JA, Donaher NA, McCarthy A, Campbell DA. The nitrogen costs of photosynthesis in a diatom under current and future pCO2. New Phytol 2015; 205:533-43. [PMID: 25256155 DOI: 10.1111/nph.13037] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/23/2014] [Accepted: 08/10/2014] [Indexed: 05/23/2023]
Abstract
With each cellular generation, oxygenic photoautotrophs must accumulate abundant protein complexes that mediate light capture, photosynthetic electron transport and carbon fixation. In addition to this net synthesis, oxygenic photoautotrophs must counter the light-dependent photoinactivation of Photosystem II (PSII), using metabolically expensive proteolysis, disassembly, resynthesis and re-assembly of protein subunits. We used growth rates, elemental analyses and protein quantitations to estimate the nitrogen (N) metabolism costs to both accumulate the photosynthetic system and to maintain PSII function in the diatom Thalassiosira pseudonana, growing at two pCO2 levels across a range of light levels. The photosynthetic system contains c. 15-25% of total cellular N. Under low growth light, N (re)cycling through PSII repair is only c. 1% of the cellular N assimilation rate. As growth light increases to inhibitory levels, N metabolite cycling through PSII repair increases to c. 14% of the cellular N assimilation rate. Cells growing under the assumed future 750 ppmv pCO2 show higher growth rates under optimal light, coinciding with a lowered N metabolic cost to maintain photosynthesis, but then suffer greater photoinhibition of growth under excess light, coincident with rising costs to maintain photosynthesis. We predict this quantitative trait response to light will vary across taxa.
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Affiliation(s)
- Gang Li
- Department of Chemistry and Biochemistry, Mount Allison University, Sackville, NB, E4L 1G7, Canada; Key Laboratory of Tropical Marine Bio-Resources and Ecology, South China Sea Institute of Oceanology, CAS, Guangzhou, 510301, China
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Wu Y, Campbell DA, Gao K. Faster recovery of a diatom from UV damage under ocean acidification. Journal of Photochemistry and Photobiology B: Biology 2014; 140:249-54. [DOI: 10.1016/j.jphotobiol.2014.08.006] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/11/2014] [Revised: 08/04/2014] [Accepted: 08/07/2014] [Indexed: 11/26/2022]
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Gao K, Campbell DA. Photophysiological responses of marine diatoms to elevated CO 2 and decreased pH: a review. Funct Plant Biol 2014; 41:449-459. [PMID: 32481004 DOI: 10.1071/fp13247] [Citation(s) in RCA: 65] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/21/2013] [Accepted: 12/24/2013] [Indexed: 05/19/2023]
Abstract
Diatoms dominate nearly half of current oceanic productivity, so their responses to ocean acidification are of general concern regarding future oceanic carbon sequestration. Community, mesocosm and laboratory studies show a range of diatom growth and photophysiological responses to increasing pCO2. Nearly 20 studies on effects of elevated pCO2 on diatoms have shown stimulations, no effects or inhibitions of growth rates. These differential responses could result from differences in experimental setups, cell densities, levels of light and temperature, but also from taxon-specific physiology. Generally, ocean acidification treatments of lowered pH with elevated CO2 stimulate diatom growth under low to moderate levels of light, but lead to growth inhibition when combined with excess light. Additionally, diatom cell sizes and their co-varying metabolic rates can influence responses to increasing pCO2 and decreasing pH, although cell size effects are confounded with taxonomic specificities in cell structures and metabolism. Here we summarise known diatom growth and photophysiological responses to increasing pCO2 and decreasing pH, and discuss some reasons for the diverse responses observed across studies.
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Affiliation(s)
- Kunshan Gao
- State Key Laboratory of Marine Environmental Science, Xiamen University, 361005 Xiamen, China
| | - Douglas A Campbell
- Department of Biology, Mount Allison University, Sackville, NB E4L 1G7, Canada
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Jeans J, Campbell DA, Hoogenboom MO. Increased reliance upon photosystem II repair following acclimation to high-light by coral-dinoflagellate symbioses. Photosynth Res 2013; 118:219-29. [PMID: 24062202 DOI: 10.1007/s11120-013-9918-y] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/24/2013] [Accepted: 08/26/2013] [Indexed: 05/22/2023]
Abstract
Changing light environments force photoautotroph cells, including coral symbionts, to acclimate to maintain photosynthesis. Photosystem II (PSII) is subjected to photoinactivation at a rate proportional to the incident light, and cells must adjust their rates of protein repair to counter this photoinactivation. We examined PSII function in the coral symbiont Symbiodinium to determine the effect of photoacclimation on their capacity for PSII repair. Colonies of the coral Stylophora pistillata were collected from moderate light environments on the Lizard Island reef (Queensland, Australia) and transported to a local field station, where they were assigned to lower or higher light regimes and allowed to acclimate for 2 weeks. Following this photoacclimation period, the low-light acclimated corals showed greater symbiont density, higher chlorophyll per symbiont cell, and higher photosystem II protein than high-light acclimated corals did. Subsequently, we treated the corals with lincomycin, an inhibitor of chloroplastic protein synthesis, and exposed them to a high-light treatment to separate the effect of de novo protein synthesis in PSII repair from intrinsic susceptibility to photoinactivation. Low-light acclimated corals showed a sharp initial drop in PSII function but inhibition of PSII repair provoked only a modest additional drop in PSII function, compared to uninhibited corals. In high-light acclimated corals inhibition of PSII repair provoked a larger drop in PSII function, compared to uninhibited high-light corals. The greater lincomycin effects in the corals pre-acclimated to high-light show that high-light leads to an increased reliance on the PSII repair cycle.
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Affiliation(s)
- Jennifer Jeans
- Biology and Biochemistry, Mount Allison University, Sackville, NB, E4L 3G7, Canada
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Jin P, Gao K, Villafañe VE, Campbell DA, Helbling EW. Ocean acidification alters the photosynthetic responses of a coccolithophorid to fluctuating ultraviolet and visible radiation. Plant Physiol 2013; 162:2084-94. [PMID: 23749851 PMCID: PMC3729784 DOI: 10.1104/pp.113.219543] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/11/2013] [Accepted: 06/03/2013] [Indexed: 05/03/2023]
Abstract
Mixing of seawater subjects phytoplankton to fluctuations in photosynthetically active radiation (400-700 nm) and ultraviolet radiation (UVR; 280-400 nm). These irradiance fluctuations are now superimposed upon ocean acidification and thinning of the upper mixing layer through stratification, which alters mixing regimes. Therefore, we examined the photosynthetic carbon fixation and photochemical performance of a coccolithophore, Gephyrocapsa oceanica, grown under high, future (1,000 μatm) and low, current (390 μatm) CO₂ levels, under regimes of fluctuating irradiances with or without UVR. Under both CO₂ levels, fluctuating irradiances, as compared with constant irradiance, led to lower nonphotochemical quenching and less UVR-induced inhibition of carbon fixation and photosystem II electron transport. The cells grown under high CO₂ showed a lower photosynthetic carbon fixation rate but lower nonphotochemical quenching and less ultraviolet B (280-315 nm)-induced inhibition. Ultraviolet A (315-400 nm) led to less enhancement of the photosynthetic carbon fixation in the high-CO₂-grown cells under fluctuating irradiance. Our data suggest that ocean acidification and fast mixing or fluctuation of solar radiation will act synergistically to lower carbon fixation by G. oceanica, although ocean acidification may decrease ultraviolet B-related photochemical inhibition.
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Affiliation(s)
- Peng Jin
- State Key Laboratory of Marine Environmental Science, Xiamen University, Xiamen 361005, China (P.J., K.G.)
- Estación de Fotobiología Playa Unión and Consejo Nacional de Investigaciones Científicas y Técnicas, Chubut 9103, Argentina (V.E.V., E.W.H.); and
- Biology Department, Mount Allison University, Sackville, New Brunswick, Canada E4L 1G7 (D.A.C.)
| | | | - Virginia E. Villafañe
- State Key Laboratory of Marine Environmental Science, Xiamen University, Xiamen 361005, China (P.J., K.G.)
- Estación de Fotobiología Playa Unión and Consejo Nacional de Investigaciones Científicas y Técnicas, Chubut 9103, Argentina (V.E.V., E.W.H.); and
- Biology Department, Mount Allison University, Sackville, New Brunswick, Canada E4L 1G7 (D.A.C.)
| | - Douglas A. Campbell
- State Key Laboratory of Marine Environmental Science, Xiamen University, Xiamen 361005, China (P.J., K.G.)
- Estación de Fotobiología Playa Unión and Consejo Nacional de Investigaciones Científicas y Técnicas, Chubut 9103, Argentina (V.E.V., E.W.H.); and
- Biology Department, Mount Allison University, Sackville, New Brunswick, Canada E4L 1G7 (D.A.C.)
| | - E. Walter Helbling
- State Key Laboratory of Marine Environmental Science, Xiamen University, Xiamen 361005, China (P.J., K.G.)
- Estación de Fotobiología Playa Unión and Consejo Nacional de Investigaciones Científicas y Técnicas, Chubut 9103, Argentina (V.E.V., E.W.H.); and
- Biology Department, Mount Allison University, Sackville, New Brunswick, Canada E4L 1G7 (D.A.C.)
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Campbell DA, Hossain Z, Cockshutt AM, Zhaxybayeva O, Wu H, Li G. Photosystem II protein clearance and FtsH function in the diatom Thalassiosira pseudonana. Photosynth Res 2013; 115:43-54. [PMID: 23504483 DOI: 10.1007/s11120-013-9809-2] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/28/2013] [Accepted: 03/01/2013] [Indexed: 05/13/2023]
Abstract
All oxygenic photoautotrophs suffer photoinactivation of their Photosystem II complexes, at a rate driven by the instantaneous light level. To maintain photosynthesis, PsbA subunits are proteolytically removed from photoinactivated Photosystem II complexes, primarily by a membrane-bound FtsH protease. Diatoms thrive in environments with fluctuating light, such as coastal regions, in part because they enjoy a low susceptibility to photoinactivation of Photosystem II. In a coastal strain of the diatom Thalassiosira pseudonana growing across a range of light levels, active Photosystem II represents only about 42 % of the total Photosystem II protein, with the remainder attributable to photoinactivated Photosystem II awaiting recycling. The rate constant for removal of PsbA protein increases with growth light, in parallel with an increasing content of the FtsH protease relative to the substrate PsbA. An offshore strain of Thalassiosira pseudonana, originating from a more stable light environment, had a lower content of FtsH and slower rate constants for removal of PsbA. We used this data to generate the first estimates for in vivo proteolytic degradation of photoinactivated PsbA per FtsH6 protease, at ~3.9 × 10(-2) s(-1), which proved consistent across growth lights and across the onshore and offshore strains.
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Affiliation(s)
- Douglas A Campbell
- Department of Chemistry and Biochemistry, Mount Allison University, Sackville, NB E4L 1G7, Canada.
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Campbell DA, Chkrebtii O. Maximum profile likelihood estimation of differential equation parameters through model based smoothing state estimates. Math Biosci 2013; 246:283-92. [PMID: 23579098 DOI: 10.1016/j.mbs.2013.03.011] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2012] [Revised: 03/22/2013] [Accepted: 03/25/2013] [Indexed: 11/29/2022]
Abstract
Statistical inference for biochemical models often faces a variety of characteristic challenges. In this paper we examine state and parameter estimation for the JAK-STAT intracellular signalling mechanism, which exemplifies the implementation intricacies common in many biochemical inference problems. We introduce an extension to the Generalized Smoothing approach for estimating delay differential equation models, addressing selection of complexity parameters, choice of the basis system, and appropriate optimization strategies. Motivated by the JAK-STAT system, we further extend the generalized smoothing approach to consider a nonlinear observation process with additional unknown parameters, and highlight how the approach handles unobserved states and unevenly spaced observations. The methodology developed is generally applicable to problems of estimation for differential equation models with delays, unobserved states, nonlinear observation processes, and partially observed histories.
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Affiliation(s)
- D A Campbell
- Department of Statistics and Actuarial Science, Simon Fraser University, Surrey Campus, 13450, 102nd Ave, Surrey BC, Canada V3T 0A3.
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Fraser JM, Tulk SE, Jeans JA, Campbell DA, Bibby TS, Cockshutt AM. Photophysiological and photosynthetic complex changes during iron starvation in Synechocystis sp. PCC 6803 and Synechococcus elongatus PCC 7942. PLoS One 2013; 8:e59861. [PMID: 23527279 PMCID: PMC3602374 DOI: 10.1371/journal.pone.0059861] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2012] [Accepted: 02/19/2013] [Indexed: 12/13/2022] Open
Abstract
Iron is an essential component in many protein complexes involved in photosynthesis, but environmental iron availability is often low as oxidized forms of iron are insoluble in water. To adjust to low environmental iron levels, cyanobacteria undergo numerous changes to balance their iron budget and mitigate the physiological effects of iron depletion. We investigated changes in key protein abundances and photophysiological parameters in the model cyanobacteria Synechococcus PCC 7942 and Synechocystis PCC 6803 over a 120 hour time course of iron deprivation. The iron stress induced protein (IsiA) accumulated to high levels within 48 h of the onset of iron deprivation, reaching a molar ratio of ∼42 IsiA : Photosystem I in Synechococcus PCC 7942 and ∼12 IsiA : Photosystem I in Synechocystis PCC 6803. Concomitantly the iron-rich complexes Cytochrome b6f and Photosystem I declined in abundance, leading to a decrease in the Photosystem I : Photosystem II ratio. Chlorophyll fluorescence analyses showed a drop in electron transport per Photosystem II in Synechococcus, but not in Synechocystis after iron depletion. We found no evidence that the accumulated IsiA contributes to light capture by Photosystem II complexes.
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Affiliation(s)
- Jared M Fraser
- Department of Chemistry & Biochemistry, Mount Allison University, Sackville, New Brunswick, Canada
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Li G, Campbell DA. Rising CO2 interacts with growth light and growth rate to alter photosystem II photoinactivation of the coastal diatom Thalassiosira pseudonana. PLoS One 2013; 8:e55562. [PMID: 23383226 PMCID: PMC3561317 DOI: 10.1371/journal.pone.0055562] [Citation(s) in RCA: 64] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2012] [Accepted: 12/27/2012] [Indexed: 11/19/2022] Open
Abstract
We studied the interactive effects of pCO2 and growth light on the coastal marine diatom Thalassiosira pseudonana CCMP 1335 growing under ambient and expected end-of-the-century pCO2 (750 ppmv), and a range of growth light from 30 to 380 µmol photons·m−2·s−1. Elevated pCO2 significantly stimulated the growth of T. pseudonana under sub-saturating growth light, but not under saturating to super-saturating growth light. Under ambient pCO2 susceptibility to photoinactivation of photosystem II (σi) increased with increasing growth rate, but cells growing under elevated pCO2 showed no dependence between growth rate and σi, so under high growth light cells under elevated pCO2 were less susceptible to photoinactivation of photosystem II, and thus incurred a lower running cost to maintain photosystem II function. Growth light altered the contents of RbcL (RUBISCO) and PsaC (PSI) protein subunits, and the ratios among the subunits, but there were only limited effects on these and other protein pools between cells grown under ambient and elevated pCO2.
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Affiliation(s)
- Gang Li
- Biology Department, Mount Allison University, Sackville, New Brunswick, Canada
- Key Laboratory of Marine Bio-resources Sustainable Utilization, South China Sea Institute of Oceanology, CAS, Guangzhou, Guangdong, China
| | - Douglas A. Campbell
- Biology Department, Mount Allison University, Sackville, New Brunswick, Canada
- * E-mail:
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Sharpe SC, Koester JA, Loebl M, Cockshutt AM, Campbell DA, Irwin AJ, Finkel ZV. Influence of cell size and DNA content on growth rate and photosystem II function in cryptic species of Ditylum brightwellii. PLoS One 2012; 7:e52916. [PMID: 23300819 PMCID: PMC3534128 DOI: 10.1371/journal.pone.0052916] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2012] [Accepted: 11/22/2012] [Indexed: 11/18/2022] Open
Abstract
DNA content and cell volume have both been hypothesized as controls on metabolic rate and other physiological traits. We use cultures of two cryptic species of Ditylum brightwellii (West) Grunow with an approximately two-fold difference in genome size and a small and large culture of each clone obtained by isolating small and large cells to compare the physiological consequences of size changes due to differences in DNA content and reduction in cell size following many generations of asexual reproduction. We quantified the growth rate, the functional absorption cross-section of photosystem II (PSII), susceptibility of PSII to photoinactivation, PSII repair capacity, and PSII reaction center proteins D1 (PsbA) and D2 (PsbD) for each culture at a range of irradiances. The species with the smaller genome has a higher growth rate and, when acclimated to growth-limiting irradiance, has higher PSII repair rate capacity, PSII functional optical absorption cross-section, and PsbA per unit protein, relative to the species with the larger genome. By contrast, cell division rates vary little within clonal cultures of the same species despite significant differences in average cell volume. Given the similarity in cell division rates within species, larger cells within species have a higher demand for biosynthetic reductant. As a consequence, larger cells within species have higher numbers of PSII per unit protein (PsbA), since PSII photochemically generates the reductant to support biosynthesis. These results suggest that DNA content, as opposed to cell volume, has a key role in setting the differences in maximum growth rate across diatom species of different size while PSII content and related photophysiological traits are influenced by both growth rate and cell size.
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Affiliation(s)
- Susan C. Sharpe
- Chemistry and Biochemistry, Mount Allison University, Sackville, New Brunswick, Canada
| | - Julie A. Koester
- School of Oceanography, University of Washington, Seattle, Washington, United States of America
- Environmental Science Program, Mount Allison University, Sackville, New Brunswick, Canada
| | - Martina Loebl
- Center for Marine Environmental Sciences (MARUM), Bremen International Graduate School for Marine Sciences (GLOMAR), University of Bremen, Bremen, Germany
| | - Amanda M. Cockshutt
- Chemistry and Biochemistry, Mount Allison University, Sackville, New Brunswick, Canada
| | | | - Andrew J. Irwin
- Mathematics and Computer Science, Mount Allison University, Sackville, New Brunswick, Canada
| | - Zoe V. Finkel
- Environmental Science Program, Mount Allison University, Sackville, New Brunswick, Canada
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Wu H, Roy S, Alami M, Green BR, Campbell DA. Photosystem II photoinactivation, repair, and protection in marine centric diatoms. Plant Physiol 2012; 160:464-76. [PMID: 22829321 PMCID: PMC3440219 DOI: 10.1104/pp.112.203067] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/03/2012] [Accepted: 07/23/2012] [Indexed: 05/02/2023]
Abstract
Diatoms are important contributors to aquatic primary production, and can dominate phytoplankton communities under variable light regimes. We grew two marine diatoms, the small Thalassiosira pseudonana and the large Coscinodiscus radiatus, across a range of temperatures and treated them with a light challenge to understand their exploitation of variable light environments. In the smaller T. pseudonana, photosystem II (PSII) photoinactivation outran the clearance of PSII protein subunits, particularly in cells grown at sub- or supraoptimal temperatures. In turn the absorption cross section serving PSII photochemistry was down-regulated in T. pseudonana through induction of a sustained phase of nonphotochemical quenching that relaxed only slowly over 30 min of subsequent low-light incubation. In contrast, in the larger diatom C. radiatus, PSII subunit turnover was sufficient to counteract a lower intrinsic susceptibility to photoinactivation, and C. radiatus thus did not need to induce sustained nonphotochemical quenching under the high-light treatment. T. pseudonana thus incurs an opportunity cost of sustained photosynthetic down-regulation after the end of an upward light shift, whereas the larger C. radiatus can maintain a balanced PSII repair cycle under comparable conditions.
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Affiliation(s)
- Hongyan Wu
- Biology, Mount Allison University, Sackville, New Brunswick, Canada E4L 1G7 (H.W., D.A.C.); College of Biological Engineering, Hubei University of Technology, Wuhan, Hubei 430068, China (H.W.); Institut des sciences de la mer de Rimouski, Université du Québec, Rimouski, Quebec, Canada G5L 3A1 (S.R.); and Botany, University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z4 (M.A., B.R.G.)
| | - Suzanne Roy
- Biology, Mount Allison University, Sackville, New Brunswick, Canada E4L 1G7 (H.W., D.A.C.); College of Biological Engineering, Hubei University of Technology, Wuhan, Hubei 430068, China (H.W.); Institut des sciences de la mer de Rimouski, Université du Québec, Rimouski, Quebec, Canada G5L 3A1 (S.R.); and Botany, University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z4 (M.A., B.R.G.)
| | - Meriem Alami
- Biology, Mount Allison University, Sackville, New Brunswick, Canada E4L 1G7 (H.W., D.A.C.); College of Biological Engineering, Hubei University of Technology, Wuhan, Hubei 430068, China (H.W.); Institut des sciences de la mer de Rimouski, Université du Québec, Rimouski, Quebec, Canada G5L 3A1 (S.R.); and Botany, University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z4 (M.A., B.R.G.)
| | - Beverley R. Green
- Biology, Mount Allison University, Sackville, New Brunswick, Canada E4L 1G7 (H.W., D.A.C.); College of Biological Engineering, Hubei University of Technology, Wuhan, Hubei 430068, China (H.W.); Institut des sciences de la mer de Rimouski, Université du Québec, Rimouski, Quebec, Canada G5L 3A1 (S.R.); and Botany, University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z4 (M.A., B.R.G.)
| | - Douglas A. Campbell
- Biology, Mount Allison University, Sackville, New Brunswick, Canada E4L 1G7 (H.W., D.A.C.); College of Biological Engineering, Hubei University of Technology, Wuhan, Hubei 430068, China (H.W.); Institut des sciences de la mer de Rimouski, Université du Québec, Rimouski, Quebec, Canada G5L 3A1 (S.R.); and Botany, University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z4 (M.A., B.R.G.)
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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). J Phycol 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] [What about the content of this article? (0)] [Affiliation(s)] [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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