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Bayramova E, Petrova D, Marchenkov A, Morozov A, Galachyants Y, Zakharova Y, Bedoshvili Y, Likhoshway Y. Differential Expression of Stress Adaptation Genes in a Diatom Ulnaria acus under Different Culture Conditions. Int J Mol Sci 2024; 25:2314. [PMID: 38396992 PMCID: PMC10888605 DOI: 10.3390/ijms25042314] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2024] [Revised: 02/11/2024] [Accepted: 02/13/2024] [Indexed: 02/25/2024] Open
Abstract
Diatoms are a group of unicellular eukaryotes that are essential primary producers in aquatic ecosystems. The dynamic nature of their habitat necessitates a quick and specific response to various stresses. However, the molecular mechanisms of their physiological adaptations are still underexplored. In this work, we study the response of the cosmopolitan freshwater diatom Ulnaria acus (Bacillariophyceae, Fragilariophycidae, Licmophorales, Ulnariaceae, Ulnaria) in relation to a range of stress factors, namely silica deficiency, prolonged cultivation, and interaction with an algicidal bacterium. Fluorescent staining and light microscopy were used to determine the physiological state of cells under these stresses. To explore molecular reactions, we studied the genes involved in the stress response-type III metacaspase (MC), metacaspase-like proteases (MCP), death-specific protein (DSP), delta-1-pyrroline-5-carboxylate dehydrogenase (ALDH12), and glutathione synthetase (GSHS). We have described the structure of these genes, analyzed the predicted amino acid sequences, and measured their expression dynamics in vitro using qRT-PCR. We demonstrated that the expression of UaMC1, UaMC3, and UaDSP increased during the first five days of silicon starvation. On the seventh day, it was replaced with the expression of UaMC2, UaGSHS, and UaALDH. After 45 days of culture, cells stopped growing, and the expression of UaMC1, UaMC2, UaGSHS, and UaDSP increased. Exposure to an algicidal bacterial filtrate induced a higher expression of UaMC1 and UaGSHS. Thus, we can conclude that these proteins are involved in diatoms' adaptions to environmental changes. Further, these data show that the molecular adaptation mechanisms in diatoms depend on the nature and exposure duration of a stress factor.
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Affiliation(s)
| | | | | | | | | | | | - Yekaterina Bedoshvili
- Limnological Institute, Siberian Branch of the Russian Academy of Sciences, 664033 Irkutsk, Russia; (E.B.); (D.P.); (A.M.); (A.M.); (Y.G.); (Y.Z.); (Y.L.)
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Chatelain P, Astier J, Wendehenne D, Rosnoblet C, Jeandroz S. Identification of Partner Proteins of the Algae Klebsormidium nitens NO Synthases: Toward a Better Understanding of NO Signaling in Eukaryotic Photosynthetic Organisms. FRONTIERS IN PLANT SCIENCE 2021; 12:797451. [PMID: 35003186 PMCID: PMC8728061 DOI: 10.3389/fpls.2021.797451] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/18/2021] [Accepted: 11/30/2021] [Indexed: 06/14/2023]
Abstract
In animals, NO is synthesized from L-arginine by three isoforms of nitric oxide synthase (NOS) enzyme. NO production and effects have also been reported in plants but the identification of its sources, especially the enzymatic ones, remains one of the critical issues in the field. NOS-like activities have been reported, although there are no homologs of mammalian NOS in the land plant genomes sequenced so far. However, several NOS homologs have been found in algal genomes and transcriptomes. A first study has characterized a functional NOS in the chlorophyte Ostreococcus tauri and the presence of NOS homologs was later confirmed in a dozen algae. These results raise the questions of the significance of the presence of NOS and their molecular diversity in algae. We hypothesize that comparisons among protein structures of the two KnNOS, together with the identification of their interacting partner proteins, might allow a better understanding of the molecular diversification and functioning of NOS in different physiological contexts and, more generally, new insights into NO signaling in photosynthetic organisms. We recently identified two NOS homologs sequences in the genome of the streptophyte Klebsormidium nitens, a model alga in the study of plant adaptation to terrestrial life. The first sequence, named KnNOS1, contains canonical NOS signatures while the second, named KnNOS2, presents a large C-ter extension including a globin domain. In order to identify putative candidates for KnNOSs partner proteins, we draw the protein-protein interaction networks of the three human NOS using the BioGRID database and hypothesized on the biological role of K. nitens orthologs. Some of these conserved partners are known to be involved in mammalian NOSs regulation and functioning. In parallel, our methodological strategy for the identification of partner proteins of KnNOS1 and KnNOS2 by in vitro pull-down assay is presented.
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Regulatory role of death specific protein in response to nutrient limitation in a marine diatom. ALGAL RES 2021. [DOI: 10.1016/j.algal.2021.102392] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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Kuo EY, Lee TM. Molecular Mechanisms Underlying the Acclimation of Chlamydomonas reinhardtii Against Nitric Oxide Stress. FRONTIERS IN PLANT SCIENCE 2021; 12:690763. [PMID: 34421944 PMCID: PMC8374494 DOI: 10.3389/fpls.2021.690763] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/04/2021] [Accepted: 06/14/2021] [Indexed: 06/13/2023]
Abstract
The acclimation mechanism of Chlamydomonas reinhardtii to nitric oxide (NO) was studied by exposure to S-nitroso-N-acetylpenicillamine (SNAP), a NO donor. Treatment with 0.1 or 0.3 mM SNAP transiently inhibited photosynthesis within 1 h, followed by a recovery, while 1.0 mM SNAP treatment caused irreversible photosynthesis inhibition and mortality. The SNAP effects are avoided in the presence of the NO scavenger, 2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-l-oxyl-3-oxide (cPTIO). RNA-seq, qPCR, and biochemical analyses were conducted to decode the metabolic shifts under NO stress by exposure to 0.3 mM SNAP in the presence or absence of 0.4 mM cPTIO. These findings revealed that the acclimation to NO stress comprises a temporally orchestrated implementation of metabolic processes: (1). modulation of NADPH oxidase (respiratory burst oxidase-like 2, RBOL2) and ROS signaling pathways for downstream mechanism regulation, (2). trigger of NO scavenging elements to reduce NO level; (3). prevention of photo-oxidative risk through photosynthesis inhibition and antioxidant defense system induction; (4). acclimation to nitrogen and sulfur shortage; (5). attenuation of transcriptional and translational activity together with degradation of damaged proteins through protein trafficking machinery (ubiquitin, SNARE, and autophagy) and molecular chaperone system for dynamic regulation of protein homeostasis. In addition, the expression of the gene encoding NADPH oxidase, RBOL2, showed a transient increase while that of RBOL1 was slightly decreased after NO challenge. It reflects that NADPH oxidase, a regulator in ROS-mediated signaling pathway, may be involved in the responses of Chlamydomonas to NO stress. In conclusion, our findings provide insight into the molecular events underlying acclimation mechanisms in Chlamydomonas to NO stress.
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Affiliation(s)
- Eva YuHua Kuo
- Department of Marine Biotechnology and Resources, National Sun Yat-sen University, Kaohsiung, Taiwan
| | - Tse-Min Lee
- Department of Marine Biotechnology and Resources, National Sun Yat-sen University, Kaohsiung, Taiwan
- Doctoral Degree Program in Marine Biotechnology, National Sun Yat-sen University, Kaohsiung, Taiwan
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Astier J, Rossi J, Chatelain P, Klinguer A, Besson-Bard A, Rosnoblet C, Jeandroz S, Nicolas-Francès V, Wendehenne D. Nitric oxide production and signalling in algae. JOURNAL OF EXPERIMENTAL BOTANY 2021; 72:781-792. [PMID: 32910824 DOI: 10.1093/jxb/eraa421] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/26/2020] [Accepted: 09/07/2020] [Indexed: 05/27/2023]
Abstract
Nitric oxide (NO) was the first identified gaseous messenger and is now well established as a major ubiquitous signalling molecule. The rapid development of our understanding of NO biology in embryophytes came with the partial characterization of the pathways underlying its production and with the decrypting of signalling networks mediating its effects. Notably, the identification of proteins regulated by NO through nitrosation greatly enhanced our perception of NO functions. In comparison, the role of NO in algae has been less investigated. Yet, studies in Chlamydomonas reinhardtii have produced key insights into NO production through the identification of NO-forming nitrite reductase and of S-nitrosated proteins. More intriguingly, in contrast to embryophytes, a few algal species possess a conserved nitric oxide synthase, the main enzyme catalysing NO synthesis in metazoans. This latter finding paves the way for a deeper characterization of novel members of the NO synthase family. Nevertheless, the typical NO-cyclic GMP signalling module transducing NO effects in metazoans is not conserved in algae, nor in embryophytes, highlighting a divergent acquisition of NO signalling between the green and the animal lineages.
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Affiliation(s)
- Jeremy Astier
- Agroécologie, AgroSup Dijon, CNRS, INRAE, Univ. Bourgogne Franche-Comté, Dijon, France
| | - Jordan Rossi
- Agroécologie, AgroSup Dijon, CNRS, INRAE, Univ. Bourgogne Franche-Comté, Dijon, France
| | - Pauline Chatelain
- Agroécologie, AgroSup Dijon, CNRS, INRAE, Univ. Bourgogne Franche-Comté, Dijon, France
| | - Agnès Klinguer
- Agroécologie, AgroSup Dijon, CNRS, INRAE, Univ. Bourgogne Franche-Comté, Dijon, France
| | - Angélique Besson-Bard
- Agroécologie, AgroSup Dijon, CNRS, INRAE, Univ. Bourgogne Franche-Comté, Dijon, France
| | - Claire Rosnoblet
- Agroécologie, AgroSup Dijon, CNRS, INRAE, Univ. Bourgogne Franche-Comté, Dijon, France
| | - Sylvain Jeandroz
- Agroécologie, AgroSup Dijon, CNRS, INRAE, Univ. Bourgogne Franche-Comté, Dijon, France
| | | | - David Wendehenne
- Agroécologie, AgroSup Dijon, CNRS, INRAE, Univ. Bourgogne Franche-Comté, Dijon, France
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Kennedy F, Martin A, McMinn A. Insights into the Production and Role of Nitric Oxide in the Antarctic Sea-ice Diatom Fragilariopsis cylindrus. JOURNAL OF PHYCOLOGY 2020; 56:1196-1207. [PMID: 32428973 DOI: 10.1111/jpy.13027] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/15/2019] [Accepted: 03/16/2020] [Indexed: 06/11/2023]
Abstract
Nitric oxide (NO) is widely recognized as an important transmitter molecule in biological systems, from animals to plants and microbes. However, the role of NO in marine photosynthetic microbes remains unclear and even less is known about the role of this metabolite in Antarctic sea-ice diatoms. Using a combination of microsensors, microfluidic chambers, and artificial sea-ice tanks, a basic mechanistic insight into NO's dynamics within the Antarctic sea-ice diatom Fragilariopsis cylindrus was obtained. Results suggest that NO production in F. cylindrus is nitrite-dependent via nitrate reductase. NO production was abolished upon exposure to light but could be induced in the light when normal photosynthetic electron flow was disrupted. The addition of exogenous NO to cellular suspensions of F. cylindrus negatively influenced growth, disrupted photosynthesis, and altered non-photochemical dissipation mechanisms. NO production was also observed when cells were exposed to stressful salinity and temperature regimes. These results suggest that during periods of environmental stress, NO could be produced in F. cylindrus as a "stress signa" molecule.
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Affiliation(s)
- Fraser Kennedy
- Institute for Marine and Antarctic Studies, University of Tasmania, Hobart, TAS, Australia
| | - Andrew Martin
- Institute for Marine and Antarctic Studies, University of Tasmania, Hobart, TAS, Australia
| | - Andrew McMinn
- Institute for Marine and Antarctic Studies, University of Tasmania, Hobart, TAS, Australia
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Zhao Y, Tang X, Qu F, Lv M, Liu Q, Li J, Li L, Zhang B, Zhao Y. ROS-mediated programmed cell death (PCD) of Thalassiosira pseudonana under the stress of BDE-47. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2020; 262:114342. [PMID: 32179226 DOI: 10.1016/j.envpol.2020.114342] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/16/2019] [Revised: 02/21/2020] [Accepted: 03/05/2020] [Indexed: 06/10/2023]
Abstract
Polybrominated diphenyl ethers (PBDEs) are a series of highly persistent organic pollutants (POPs) ubiquitously distributed in marine environments. As key primary producers, microalgae are the start of PBDEs bioaccumulations and vulnerable to their toxicities. In order to deeply investigate the toxic mechanism of PBDEs on microalgal cells, the occurrence of programmed cell death (PCD) in a model diatom Thalassiosira pseudonana and its possible mediating mechanism were studied. The results indicated: cell death of T. pseudonana happened under the stress of BDE-47, which was proved to be PCD based on the correlations with three biochemical markers (DNA fragmentation, phosphatidylserine externalization and caspase activity) and three molecular markers [Metacaspase 2 gene (TpMC2), Death-associated protein gene (DAP3) and Death-specific protein 1 gene (TpDSP1)]; Furthermore, the changes of cellular ROS levels were correlated with the PCD markers and the dead cell rates, and the cell membrane and the chloroplast were identified as the major ROS production sites. Therefore, we concluded that PCD might be an important toxic mechanism of PBDEs on microalgal cells, and that chloroplast- and cell membrane-produced ROS was an important signaling molecule to mediate the PCD activation process. Our research firstly indicated microalgal PCD could be induced by PBDEs, and increased our knowledge of the toxic mechanisms by which POPs affect microalgal cells.
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Affiliation(s)
- Yirong Zhao
- College of Marine Life Sciences, Department of Marine Ecology, Ocean University of China, Qingdao, 266003, China
| | - Xuexi Tang
- College of Marine Life Sciences, Department of Marine Ecology, Ocean University of China, Qingdao, 266003, China; Laboratory for Marine Ecology and Environmental Science, Qingdao National Laboratory for Marine Science and Technology, Qingdao, 266071, China
| | - Fangyuan Qu
- First Institute of Oceanography, Ministry of Natural Resources, Qingdao, 266061, China
| | - Mengchen Lv
- College of Marine Life Sciences, Department of Marine Ecology, Ocean University of China, Qingdao, 266003, China
| | - Qian Liu
- College of Marine Life Sciences, Department of Marine Ecology, Ocean University of China, Qingdao, 266003, China
| | - Jun Li
- College of Marine Life Sciences, Department of Marine Ecology, Ocean University of China, Qingdao, 266003, China
| | - Luying Li
- College of Marine Life Sciences, Department of Marine Ecology, Ocean University of China, Qingdao, 266003, China
| | - Bihan Zhang
- College of Marine Life Sciences, Department of Marine Ecology, Ocean University of China, Qingdao, 266003, China
| | - Yan Zhao
- College of Marine Life Sciences, Department of Marine Ecology, Ocean University of China, Qingdao, 266003, China; Laboratory for Marine Ecology and Environmental Science, Qingdao National Laboratory for Marine Science and Technology, Qingdao, 266071, China.
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Valegård K, Andralojc PJ, Haslam RP, Pearce FG, Eriksen GK, Madgwick PJ, Kristoffersen AK, van Lun M, Klein U, Eilertsen HC, Parry MAJ, Andersson I. Structural and functional analyses of Rubisco from arctic diatom species reveal unusual posttranslational modifications. J Biol Chem 2018; 293:13033-13043. [PMID: 29925588 DOI: 10.1074/jbc.ra118.003518] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2018] [Revised: 06/19/2018] [Indexed: 01/09/2023] Open
Abstract
The catalytic performance of the major CO2-assimilating enzyme, ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco), restricts photosynthetic productivity. Natural diversity in the catalytic properties of Rubisco indicates possibilities for improvement. Oceanic phytoplankton contain some of the most efficient Rubisco enzymes, and diatoms in particular are responsible for a significant proportion of total marine primary production as well as being a major source of CO2 sequestration in polar cold waters. Until now, the biochemical properties and three-dimensional structures of Rubisco from diatoms were unknown. Here, diatoms from arctic waters were collected, cultivated, and analyzed for their CO2-fixing capability. We characterized the kinetic properties of five and determined the crystal structures of four Rubiscos selected for their high CO2-fixing efficiency. The DNA sequences of the rbcL and rbcS genes of the selected diatoms were similar, reflecting their close phylogenetic relationship. The Vmax and Km for the oxygenase and carboxylase activities at 25 °C and the specificity factors (Sc/o) at 15, 25, and 35 °C were determined. The Sc/o values were high, approaching those of mono- and dicot plants, thus exhibiting good selectivity for CO2 relative to O2 Structurally, diatom Rubiscos belong to form I C/D, containing small subunits characterized by a short βA-βB loop and a C-terminal extension that forms a β-hairpin structure (βE-βF loop). Of note, the diatom Rubiscos featured a number of posttranslational modifications of the large subunit, including 4-hydroxyproline, β-hydroxyleucine, hydroxylated and nitrosylated cysteine, mono- and dihydroxylated lysine, and trimethylated lysine. Our studies suggest adaptation toward achieving efficient CO2 fixation in arctic diatom Rubiscos.
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Affiliation(s)
- Karin Valegård
- From the Department of Cell and Molecular Biology, Uppsala University, Box 596, S-751 24 Uppsala, Sweden
| | - P John Andralojc
- Department of Plant Science, Rothamsted Research, Harpenden, Herts AL5 2JQ, United Kingdom
| | - Richard P Haslam
- Department of Plant Science, Rothamsted Research, Harpenden, Herts AL5 2JQ, United Kingdom
| | - F Grant Pearce
- From the Department of Cell and Molecular Biology, Uppsala University, Box 596, S-751 24 Uppsala, Sweden
| | - Gunilla K Eriksen
- the Norwegian College of Fisheries Science, Arctic University of Norway, N-9037 Tromsø, Norway, and
| | - Pippa J Madgwick
- Department of Plant Science, Rothamsted Research, Harpenden, Herts AL5 2JQ, United Kingdom
| | - Anne K Kristoffersen
- the Department of Biosciences, University of Oslo, P.O. Box 1066, Blindern, N-0316 Oslo, Norway
| | - Michiel van Lun
- From the Department of Cell and Molecular Biology, Uppsala University, Box 596, S-751 24 Uppsala, Sweden
| | - Uwe Klein
- the Department of Biosciences, University of Oslo, P.O. Box 1066, Blindern, N-0316 Oslo, Norway
| | - Hans C Eilertsen
- the Norwegian College of Fisheries Science, Arctic University of Norway, N-9037 Tromsø, Norway, and
| | - Martin A J Parry
- Department of Plant Science, Rothamsted Research, Harpenden, Herts AL5 2JQ, United Kingdom
| | - Inger Andersson
- From the Department of Cell and Molecular Biology, Uppsala University, Box 596, S-751 24 Uppsala, Sweden,
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Hespen CW, Bruegger JJ, Guo Y, Marletta MA. Native Alanine Substitution in the Glycine Hinge Modulates Conformational Flexibility of Heme Nitric Oxide/Oxygen (H-NOX) Sensing Proteins. ACS Chem Biol 2018; 13:1631-1639. [PMID: 29757599 DOI: 10.1021/acschembio.8b00248] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Heme nitric oxide/oxygen sensing (H-NOX) domains are direct NO sensors that regulate a variety of biological functions in both bacteria and eukaryotes. Previous work on H-NOX proteins has shown that upon NO binding, a conformational change occurs along two glycine residues on adjacent helices (termed the glycine hinge). Despite the apparent importance of the glycine hinge, it is not fully conserved in all H-NOX domains. Several H-NOX sensors from the family Flavobacteriaceae contain a native alanine substitution in one of the hinge residues. In this work, the effect of the increased steric bulk within the Ala-Gly hinge on H-NOX function was investigated. The hinge in Kordia algicida OT-1 ( Ka H-NOX) is composed of A71 and G145. Ligand-binding properties and signaling function for this H-NOX were characterized. The variant A71G was designed to convert the hinge region of Ka H-NOX to the typical Gly-Gly motif. In activity assays with its cognate histidine kinase (HnoK), the wild type displayed increased signal specificity compared to A71G. Increasing titrations of unliganded A71G gradually inhibits HnoK autophosphorylation, while increasing titrations of unliganded wild type H-NOX does not inhibit HnoK. Crystal structures of both wild type and A71G Ka H-NOX were solved to 1.9 and 1.6 Å, respectively. Regions of H-NOX domains previously identified as involved in protein-protein interactions with HnoK display significantly higher b-factors in A71G compared to wild-type H-NOX. Both biochemical and structural data indicate that the hinge region controls overall conformational flexibility of the H-NOX, affecting NO complex formation and regulation of its HnoK.
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Affiliation(s)
- Charles W. Hespen
- QB3 Institute, University of California—Berkeley, 356 Stanley Hall, Berkeley, California 94720-3220, United States
| | - Joel J. Bruegger
- QB3 Institute, University of California—Berkeley, 356 Stanley Hall, Berkeley, California 94720-3220, United States
| | - Yirui Guo
- QB3 Institute, University of California—Berkeley, 356 Stanley Hall, Berkeley, California 94720-3220, United States
| | - Michael A. Marletta
- QB3 Institute, University of California—Berkeley, 356 Stanley Hall, Berkeley, California 94720-3220, United States
- Department of Chemistry, Department of Molecular and Cell Biology, QB3 Institute, University of California—Berkeley, 374B Stanley Hall, Berkeley, California 94720-3220, United States
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Tutar O, Marín-Guirao L, Ruiz JM, Procaccini G. Antioxidant response to heat stress in seagrasses. A gene expression study. MARINE ENVIRONMENTAL RESEARCH 2017; 132:94-102. [PMID: 29126631 DOI: 10.1016/j.marenvres.2017.10.011] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/19/2017] [Revised: 10/16/2017] [Accepted: 10/22/2017] [Indexed: 05/03/2023]
Abstract
Seawater warming associated to the ongoing climate change threatens functioning and survival of keystone coastal benthic species such as seagrasses. Under elevated temperatures, the production of reactive oxygen species (ROS) is increased and plants must activate their antioxidant defense mechanisms to protect themselves from oxidative damage. Here we explore from a molecular perspective the ability of Mediterranean seagrasses to activate heat stress response mechanisms, with particular focus on antioxidants. The level of expression of targeted genes was analyzed in shallow and deep plants of the species Posidonia oceanica and in shallow plants of Cymodocea nodosa along an acute heat exposure of several days and after recovery. The overall gene expression response of P. oceanica was more intense and complete than in C. nodosa and reflected a higher oxidative stress level during the experimental heat exposure. The strong activation of genes with chaperone activity (heat shock proteins and a luminal binding protein) just in P. oceanica plants, suggested the higher sensitivity of the species to increased temperatures. In spite of the interspecific differences, genes from the superoxide dismutase (SOD) family seem to play a pivotal role in the thermal stress response of Mediterranean seagrasses as previously reported for other marine plant species. Shallow and deep P. oceanica ecotypes showed a different timing of response to heat. Shallow plants early responded to heat and after a few days relaxed their response which suggests a successful early metabolic adjustment. The response of deep plants was delayed and their recovery incomplete evidencing a lower resilience to heat in respect to shallow ecotypes. Moreover, shallow ecotypes showed some degree of pre-adaptation to heat as most analyzed genes showed higher constitutive expression levels than in deep ecotypes. The recurrent exposure of shallow plants to elevated summer temperatures has likely endowed them with a higher basal level of antioxidant defense and a faster responsiveness to warming than deep plants. Our findings match with previous physiological studies and supported the idea that warming will differently impact Mediterranean seagrass meadows depending on the species as well as on the depth (i.e. thermal regimen) at which the meadow grows. The increase in the incidence of summer heat waves could therefore produce a significant change in the distribution and composition of Mediterranean seagrass meadows with considerable consequences for the functioning of the whole ecosystem and for the socio-economic services that these ecosystems offer to the riverine populations.
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Affiliation(s)
- O Tutar
- Integrative Marine Ecology, Stazione Zoologica Anton Dohrn, Villa Comunale, 80121 Napoli, Italy; Department of Earth and Environmental Sciences, University Milano-Bicocca, Piazza della Scienza, 4-20126 Milano, Italy
| | - L Marín-Guirao
- Integrative Marine Ecology, Stazione Zoologica Anton Dohrn, Villa Comunale, 80121 Napoli, Italy.
| | - J M Ruiz
- Seagrass Ecology Group, Oceanographic Center of Murcia, Spanish Institute of Oceanography, C/ Varadero, 30740 San Pedro del Pinatar, Murcia, Spain
| | - G Procaccini
- Integrative Marine Ecology, Stazione Zoologica Anton Dohrn, Villa Comunale, 80121 Napoli, Italy
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Autoinhibitory sterol sulfates mediate programmed cell death in a bloom-forming marine diatom. Nat Commun 2017; 8:1292. [PMID: 29101388 PMCID: PMC5670183 DOI: 10.1038/s41467-017-01300-1] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2017] [Accepted: 09/07/2017] [Indexed: 01/07/2023] Open
Abstract
Cell mortality is a key mechanism that shapes phytoplankton blooms and species dynamics in aquatic environments. Here we show that sterol sulfates (StS) are regulatory molecules of a cell death program in Skeletonema marinoi, a marine diatom-blooming species in temperate coastal waters. The molecules trigger an oxidative burst and production of nitric oxide in a dose-dependent manner. The intracellular level of StS increases with cell ageing and ultimately leads to a mechanism of apoptosis-like death. Disrupting StS biosynthesis by inhibition of the sulfonation step significantly delays the onset of this fatal process and maintains steady growth in algal cells for several days. The autoinhibitory activity of StS demonstrates the functional significance of small metabolites in diatoms. The StS pathway provides another view on cell regulation during bloom dynamics in marine habitats and opens new opportunities for the biochemical control of mass-cultivation of microalgae. Phytoplankton blooms are shaped by a period of rapid growth followed by massive cell death. Here the authors show that sterol sulfates accumulate in aging cells of a bloom-forming marine diatom and trigger an oxidative burst that leads to a mechanism of apoptosis-like death.
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13
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Wang H, Butt L, Rooks P, Khan F, Allen MJ, Ali ST. Characterisation of algicidal bacterial exometabolites against the lipid-accumulating diatom Skeletonema sp. ALGAL RES 2016. [DOI: 10.1016/j.algal.2015.11.012] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Insights into possible cell-death markers in the diatom Skeletonema marinoi in response to senescence and silica starvation. Mar Genomics 2015; 24 Pt 1:81-8. [DOI: 10.1016/j.margen.2015.06.008] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2015] [Revised: 05/18/2015] [Accepted: 06/15/2015] [Indexed: 10/23/2022]
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15
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Muhseen ZT, Xiong Q, Chen Z, Ge F. Proteomics studies on stress responses in diatoms. Proteomics 2015; 15:3943-53. [PMID: 26364674 DOI: 10.1002/pmic.201500165] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2015] [Revised: 08/09/2015] [Accepted: 09/09/2015] [Indexed: 01/09/2023]
Abstract
Diatoms are a highly diverse group of eukaryotic phytoplankton that are distributed throughout marine and freshwater environments and are believed to be responsible for approximately 40% of the total marine primary productivity. The ecological success of diatoms suggests that they have developed a range of strategies to cope with various biotic and abiotic stress factors. It is of great interest to understand the adaptive responses of diatoms to different stresses in the marine environment. Proteomic technologies have been applied to the adaptive responses of marine diatoms under different growth conditions in recent years such as nitrogen starvation, iron limitation and phosphorus deficiency. These studies have provided clues to elucidate the sophisticated sensing mechanisms that control their adaptive responses. Although only a very limited number of proteomic studies were conducted in diatoms, the obtained data have led to a better understanding of the biochemical processes that contribute to their ecological success. This review presents the current status of proteomic studies of diatom stress responses and discusses the novel developments and applications for the analysis of protein post-translational modification in diatoms. The potential future application of proteomics could contribute to a better understanding of the physiological mechanisms underlying diatom acclimation to a given stress and the acquisition of an enhanced diatom stress tolerance. Future challenges and research opportunities in the proteomics studies of diatoms are also discussed.
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Affiliation(s)
- Ziyad Tariq Muhseen
- Key Laboratory of Algal Biology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, P. R. China.,University of Chinese Academy of Sciences, Beijing, P. R. China
| | - Qian Xiong
- Key Laboratory of Algal Biology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, P. R. China
| | - Zhuo Chen
- Key Laboratory of Algal Biology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, P. R. China
| | - Feng Ge
- Key Laboratory of Algal Biology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, P. R. China
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16
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Ji N, Li L, Lin L, Lin S. Screening for Suitable Reference Genes for Quantitative Real-Time PCR in Heterosigma akashiwo (Raphidophyceae). PLoS One 2015; 10:e0132183. [PMID: 26133173 PMCID: PMC4489630 DOI: 10.1371/journal.pone.0132183] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2015] [Accepted: 06/10/2015] [Indexed: 11/24/2022] Open
Abstract
The raphidophyte Heterosigma akashiwo is a globally distributed harmful alga that has been associated with fish kills in coastal waters. To understand the mechanisms of H. akashiwo bloom formation, gene expression analysis is often required. To accurately characterize the expression levels of a gene of interest, proper reference genes are essential. In this study, we assessed ten of the previously reported algal candidate genes (rpL17-2, rpL23, cox2, cal, tua, tub, ef1, 18S, gapdh, and mdh) for their suitability as reference genes in this species. We used qRT-PCR to quantify the expression levels of these genes in H. akashiwo grown under different temperatures, light intensities, nutrient concentrations, and time points over a diel cycle. The expression stability of these genes was evaluated using geNorm and NormFinder algorithms. Although none of these genes exhibited invariable expression levels, cal, tub, rpL17-2 and rpL23 expression levels were the most stable across the different conditions tested. For further validation, these selected genes were used to normalize the expression levels of ribulose-1, 5-bisphosphate carboxylase/oxygenase large unite (HrbcL) over a diel cycle. Results showed that the expression of HrbcL normalized against each of these reference genes was the highest at midday and lowest at midnight, similar to the diel patterns typically documented for this gene in algae. While the validated reference genes will be useful for future gene expression studies on H. akashiwo, we expect that the procedure used in this study may be helpful to future efforts to screen reference genes for other algae.
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Affiliation(s)
- Nanjing Ji
- State Key Laboratory of Marine Environmental Science, Xiamen University, Xiamen, Fujian 361005, China
| | - Ling Li
- State Key Laboratory of Marine Environmental Science, Xiamen University, Xiamen, Fujian 361005, China
| | - Lingxiao Lin
- State Key Laboratory of Marine Environmental Science, Xiamen University, Xiamen, Fujian 361005, China
| | - Senjie Lin
- State Key Laboratory of Marine Environmental Science, Xiamen University, Xiamen, Fujian 361005, China
- Department of Marine Sciences, University of Connecticut, Groton, Connecticut 06340, United States of America
- * E-mail:
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17
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Nitric oxide in marine photosynthetic organisms. Nitric Oxide 2015; 47:34-9. [PMID: 25795592 DOI: 10.1016/j.niox.2015.03.001] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2014] [Revised: 03/10/2015] [Accepted: 03/11/2015] [Indexed: 12/22/2022]
Abstract
Nitric oxide is a versatile and powerful signaling molecule in plants. However, most of our understanding stems from studies on terrestrial plants and very little is known about marine autotrophs. This review summarizes current knowledge about the source of nitric oxide synthesis in marine photosynthetic organisms and its role in various physiological processes under normal and stress conditions. The interactions of nitric oxide with other stress signals and cross talk among secondary messengers are also highlighted.
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18
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Bidle KD. The molecular ecophysiology of programmed cell death in marine phytoplankton. ANNUAL REVIEW OF MARINE SCIENCE 2014; 7:341-75. [PMID: 25251265 DOI: 10.1146/annurev-marine-010213-135014] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Planktonic, prokaryotic, and eukaryotic photoautotrophs (phytoplankton) share a diverse and ancient evolutionary history, during which time they have played key roles in regulating marine food webs, biogeochemical cycles, and Earth's climate. Because phytoplankton represent the basis of marine ecosystems, the manner in which they die critically determines the flow and fate of photosynthetically fixed organic matter (and associated elements), ultimately constraining upper-ocean biogeochemistry. Programmed cell death (PCD) and associated pathway genes, which are triggered by a variety of nutrient stressors and are employed by parasitic viruses, play an integral role in determining the cell fate of diverse photoautotrophs in the modern ocean. Indeed, these multifaceted death pathways continue to shape the success and evolutionary trajectory of diverse phytoplankton lineages at sea. Research over the past two decades has employed physiological, biochemical, and genetic techniques to provide a novel, comprehensive, mechanistic understanding of the factors controlling this key process. Here, I discuss the current understanding of the genetics, activation, and regulation of PCD pathways in marine model systems; how PCD evolved in unicellular photoautotrophs; how it mechanistically interfaces with viral infection pathways; how stress signals are sensed and transduced into cellular responses; and how novel molecular and biochemical tools are revealing the impact of PCD genes on the fate of natural phytoplankton assemblages.
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Affiliation(s)
- Kay D Bidle
- Department of Marine and Coastal Sciences, Rutgers University, New Brunswick, New Jersey 08901;
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19
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The effect of polyunsaturated aldehydes on Skeletonema marinoi (Bacillariophyceae): the involvement of reactive oxygen species and nitric oxide. Mar Drugs 2014; 12:4165-87. [PMID: 25026265 PMCID: PMC4113821 DOI: 10.3390/md12074165] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2014] [Revised: 06/04/2014] [Accepted: 06/30/2014] [Indexed: 12/24/2022] Open
Abstract
Nitric oxide (NO) and reactive oxygen species (ROS) production was investigated in the marine diatom, Skeletonema marinoi (SM), exposed to 2E,4E/Z-decadienal (DECA), 2E,4E/Z-octadienal (OCTA), 2E,4E/Z-heptadienal (HEPTA) and a mix of these last two (MIX). When exposed to polyunsaturated aldehydes (PUA), a decrease of NO was observed, proportional to the PUA concentration (85% of the initial level after 180 min with 66 µM DECA). Only OCTA, HEPTA and MIX induced a parallel increase of ROS, the highest (2.9-times the control) with OCTA concentrations twice the EC50 for growth at 24 h (20 μM). The synthesis of carotenoids belonging to the xanthophyll cycle (XC) was enhanced during exposure, suggesting their antioxidant activity. Our data provide evidence that specific pathways exist as a reaction to PUA and that they depend upon the PUA used and/or the diatom species. In fact, Phaeodactylum tricornutum (PT) produces NO in response to DECA, but not to OCTA. We advance the hypothesis that SM perceives OCTA and HEPTA as intra-population infochemicals (as it produces PUA), while PT (non-PUA producing species) perceives them as allelochemicals. The ability to produce and to use PUA as infochemicals may underlie ecological traits of different diatom species and modulate ecological success in natural communities.
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20
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Chen Z, Yang MK, Li CY, Wang Y, Zhang J, Wang DB, Zhang XE, Ge F. Phosphoproteomic analysis provides novel insights into stress responses in Phaeodactylum tricornutum, a model diatom. J Proteome Res 2014; 13:2511-23. [PMID: 24712722 DOI: 10.1021/pr401290u] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Protein phosphorylation on serine, threonine, and tyrosine (Ser/Thr/Tyr) is well established as a key regulatory posttranslational modification used in signal transduction to control cell growth, proliferation, and stress responses. However, little is known about its extent and function in diatoms. Phaeodactylum tricornutum is a unicellular marine diatom that has been used as a model organism for research on diatom molecular biology. Although more than 1000 protein kinases and phosphatases with specificity for Ser/Thr/Tyr residues have been predicted in P. tricornutum, no phosphorylation event has so far been revealed by classical biochemical approaches. Here, we performed a global phosphoproteomic analysis combining protein/peptide fractionation, TiO(2) enrichment, and LC-MS/MS analyses. In total, we identified 264 unique phosphopeptides, including 434 in vivo phosphorylated sites on 245 phosphoproteins. The phosphorylated proteins were implicated in the regulation of diverse biological processes, including signaling, metabolic pathways, and stress responses. Six identified phosphoproteins were further validated by Western blotting using phospho-specific antibodies. The functions of these proteins are discussed in the context of signal transduction networks in P. tricornutum. Our results advance the current understanding of diatom biology and will be useful for elucidating the phosphor-relay signaling networks in this model diatom.
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Affiliation(s)
- Zhuo Chen
- State Key Laboratory of Virology, Wuhan Institute of Virology, Chinese Academy of Sciences , Wuhan 430071, China
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21
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Johnson JG, Janech MG, Van Dolah FM. Caspase-like activity during aging and cell death in the toxic dinoflagellate Karenia brevis. HARMFUL ALGAE 2014; 31:41-53. [PMID: 28040110 DOI: 10.1016/j.hal.2013.08.005] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/24/2013] [Revised: 08/27/2013] [Accepted: 08/28/2013] [Indexed: 06/06/2023]
Abstract
The observation of caspase-like activity during cell death has provided a new framework for understanding the evolutionary and ecological contexts of programmed cell death in phytoplankton. However, additional roles for this caspase-like activity, the enzymes responsible, and the targets of this enzyme activity in phytoplankton remain largely undefined. In the present study, the role of caspase-like activity in aging and ROS-mediated cell death were investigated and death programs both dependent on and independent of caspase-like activity were observed in the toxic dinoflagellate, Karenia brevis. The dual use of in situ caspase 3/7 and TUNEL staining identified previously undescribed death-associated morphotypes in K. brevis. In silico motif analysis identified several enzymes with predicted caspase-like activity in the K. brevis transcriptome, although bona fide caspases are absent. Lastly, computational prediction of downstream caspase substrates, using sequence context and predicted secondary structure, identified proteins involved in a wide range of biological processes including regulation of protein turnover, cell cycle progression, lipid metabolism, coenzyme metabolism, apoptotic and autophagic death. To confirm the computational predictions, a short peptide was designed around the predicated caspase cleavage site in a predicted novel K. brevis caspase 3/7-like target, S-adenosylmethionine synthetase (KbAdoMetS). Cleavage of the peptide substrate with recombinant caspase 3 enzyme was determined by MALDI-TOF MS, confirming that KbAdoMetS is indeed a bona fide caspase substrate. These data identify the involvement of caspase-like activity in both aging and cell death in K. brevis and identify novel executioner enzymes and downstream targets that may be important for bloom termination.
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Affiliation(s)
- Jillian G Johnson
- NOAA Center for Coastal Environmental Health and Biomolecular Research, Charleston, SC, USA; Marine Biomedicine and Environmental Sciences Program, Medical University of South Carolina, Charleston, SC, USA.
| | - Michael G Janech
- Marine Biomedicine and Environmental Sciences Program, Medical University of South Carolina, Charleston, SC, USA; Department of Medicine, Division of Nephrology, Medical University of South Carolina, Charleston, SC, USA.
| | - Frances M Van Dolah
- NOAA Center for Coastal Environmental Health and Biomolecular Research, Charleston, SC, USA; Marine Biomedicine and Environmental Sciences Program, Medical University of South Carolina, Charleston, SC, USA.
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22
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Death-specific protein in a marine diatom regulates photosynthetic responses to iron and light availability. Proc Natl Acad Sci U S A 2013; 110:20123-8. [PMID: 24277817 DOI: 10.1073/pnas.1304727110] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Diatoms, unicellular phytoplankton that account for ∼40% of marine primary productivity, often dominate coastal and open-ocean upwelling zones. Limitation of growth and productivity by iron at low light is attributed to an elevated cellular Fe requirement for the synthesis of Fe-rich photosynthetic proteins. In the dynamic coastal environment, Fe concentrations and daily surface irradiance levels can vary by two to three orders of magnitude on short spatial and temporal scales. Although genome-wide studies are beginning to provide insight into the molecular mechanisms used by diatoms to rapidly respond to such fluxes, their functional role in mediating the Fe stress response remains uncharacterized. Here, we show, using reverse genetics, that a death-specific protein (DSP; previously named for its apparent association with cell death) in the coastal diatom Thalassiosira pseudonana (TpDSP1) localizes to the plastid and enhances growth during acute Fe limitation at subsaturating light by increasing the photosynthetic efficiency of carbon fixation. Clone lines overexpressing TpDSP1 had a lower quantum requirement for growth, increased levels of photosynthetic and carbon fixation proteins, and increased cyclic electron flow around photosystem I. Cyclic electron flow is an ATP-producing pathway essential in higher plants and chlorophytes with a heretofore unappreciated role in diatoms. However, cells under replete conditions were characterized as having markedly reduced growth and photosynthetic rates at saturating light, thereby constraining the benefits afforded by overexpression. Widespread distribution of DSP-like sequences in environmental metagenomic and metatranscriptomic datasets highlights the presence and relevance of this protein in natural phytoplankton populations in diverse oceanic regimes.
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23
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Grouneva I, Gollan PJ, Kangasjärvi S, Suorsa M, Tikkanen M, Aro EM. Phylogenetic viewpoints on regulation of light harvesting and electron transport in eukaryotic photosynthetic organisms. PLANTA 2013; 237:399-412. [PMID: 22971817 DOI: 10.1007/s00425-012-1744-5] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/29/2012] [Accepted: 08/03/2012] [Indexed: 06/01/2023]
Abstract
The comparative study of photosynthetic regulation in the thylakoid membrane of different phylogenetic groups can yield valuable insights into mechanisms, genetic requirements and redundancy of regulatory processes. This review offers a brief summary on the current understanding of light harvesting and photosynthetic electron transport regulation in different photosynthetic eukaryotes, with a special focus on the comparison between higher plants and unicellular algae of secondary endosymbiotic origin. The foundations of thylakoid structure, light harvesting, reversible protein phosphorylation and PSI-mediated cyclic electron transport are traced not only from green algae to vascular plants but also at the branching point between the "green" and the "red" lineage of photosynthetic organisms. This approach was particularly valuable in revealing processes that (1) are highly conserved between phylogenetic groups, (2) serve a common physiological role but nevertheless originate in divergent genetic backgrounds or (3) are missing in one phylogenetic branch despite their unequivocal importance in another, necessitating a search for alternative regulatory mechanisms and interactions.
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Affiliation(s)
- Irina Grouneva
- Molecular Plant Biology, University of Turku, Tykistökatu 6A, Turku, Finland.
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24
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Taylor RL, Rand JD, Caldwell GS. Treatment with algae extracts promotes flocculation, and enhances growth and neutral lipid content in Nannochloropsis oculata--a candidate for biofuel production. MARINE BIOTECHNOLOGY (NEW YORK, N.Y.) 2012; 14:774-781. [PMID: 22527265 DOI: 10.1007/s10126-012-9441-8] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/11/2011] [Accepted: 03/20/2012] [Indexed: 05/31/2023]
Abstract
Marine microalgae represent a potentially valuable feedstock for biofuel production; however, large-scale production is not yet economically viable. Optimisation of productivity and lipid yields is required and the cost of biomass harvesting and dewatering must be significantly reduced. Microalgae produce a wide variety of biologically active metabolites, many of which are involved in inter- and intra-specific interactions (the so-called infochemicals). The majority of infochemicals remain unidentified or uncharacterised. Here, we apply known and candidate (undefined extracts) infochemicals as a potential means to manipulate the growth and lipid content of Nannochloropsis oculata-a prospective species for biofuel production. Five known infochemicals (β-cyclocitral, trans,trans-2,4-decadienal, hydrogen peroxide, norharman and tryptamine) and crude extracts prepared from Skeletonema marinoi and Dunaliella salina cultures at different growth stages were assayed for impacts on N. oculata over 24 h. The neutral lipid content of N. oculata increased significantly with exposure to three infochemicals (β-cyclocitral, decadienal and norharman); however the effective concentrations affected a significant decrease in growth. Exposure to particular crude extracts significantly increased both growth and neutral lipid levels. In addition, water-soluble extracts of senescent S. marinoi cultures induced a degree of flocculation in the N. oculata. These preliminary results indicate that artificial manipulation of N. oculata cultures by application of algae infochemicals could provide a valuable tool towards achieving economically viable large-scale algae biofuel production.
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Affiliation(s)
- Rebecca L Taylor
- School of Marine Science and Technology, Newcastle University, Ridley Building, Claremont Road, Newcastle upon Tyne, NE1 7RU, England, UK
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25
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Hawkins TD, Davy SK. Nitric oxide production and tolerance differ among Symbiodinium types exposed to heat stress. PLANT & CELL PHYSIOLOGY 2012; 53:1889-1898. [PMID: 22992385 DOI: 10.1093/pcp/pcs127] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Nitric oxide (NO) is a ubiquitous molecule and its involvement in metazoan-microbe symbiosis is well known. Evidence suggests that it plays a role in the temperature-induced breakdown ('bleaching') of the ecologically important cnidarian-dinoflagellate association, and this can often lead to widespread mortality of affected hosts. This study confirms that dinoflagellates of the genus Symbiodinium can produce NO and that production of the compound is differentially regulated in different types when exposed to elevated temperature. Temperature-sensitive type B1 cells under heat stress (8°C above ambient) exhibited significant increases in NO synthesis, which occurred alongside pronounced photoinhibition and cell mortality. Tolerant type A1 cells also displayed increases in NO production, yet maintained photosynthetic yields at levels similar to those of untreated cells and displayed less dramatic increases in cell death. Type C1 cells displayed a down-regulation of NO synthesis at high temperature, and no significant mortality increases were observed in this type. Temperature-induced mortality in types A1 and B1 was affected by the prevailing level of NO and, furthermore, photosynthetic yields of these temperature-tolerant and -sensitive types appeared differentially susceptible to NO donated by pharmacological agents. Taken together, these differences in NO synthesis and tolerance could potentially influence the varying bleaching responses seen among hosts harboring different Symbiodinium types.
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Affiliation(s)
- Thomas D Hawkins
- School of Biological Sciences, Victoria University of Wellington, Wellington 6140, New Zealand
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26
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Xu Y, Feng Y, Li H, Gao Z. Ferric citrate CYP2E1-independently promotes alcohol-induced apoptosis in HepG2 cells via oxidative/nitrative stress which is attenuated by pretreatment with baicalin. Food Chem Toxicol 2012; 50:3264-72. [PMID: 22699086 DOI: 10.1016/j.fct.2012.05.061] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2012] [Revised: 05/19/2012] [Accepted: 05/31/2012] [Indexed: 12/26/2022]
Abstract
In the case of alcoholic liver injury, an iron overload is always present. Both alcohol and iron can individually induce oxidative stress in liver. However, the combined effect of physiological concentrations of alcohol and iron on oxidative stress in hepatocytes remains unknown. Baicalin has been demonstrated to be an antioxidant or iron chelator in animal experiments. In this study, we investigated the injury to hepatocytes CYP2E1-independently induced by the combination of alcohol and iron and the protective effect of baicalin. Compared with cells treated with ethanol alone, ferric citrate enhanced the accumulation of reactive oxygen and nitrogen species, increased the occurrence of protein carbonylation/nitration and the levels of 4-hydroxy-2-nonenal, changed the distribution of iNOS, and eventually resulted in apoptosis. However, pretreatment with baicalin inhibited the oxidative stress induced by the combination of alcohol and iron, mainly by chelating iron. Our findings therefore suggest that iron could CPY2E1-independently enhance the oxidative stress induced by alcohol, which probably contributes to the pathogenesis of alcoholic liver disease. Baicalin is a promising phytomedicine for preventing alcoholic liver disease.
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Affiliation(s)
- Yan Xu
- School of Chemistry and Chemical Engineering, Huazhong University of Science & Technology, Wuhan 430074, PR China
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27
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Hsu YT, Lee TM. Nitric oxide up-regulates the expression of methionine sulfoxide reductase genes in the intertidal macroalga Ulva fasciata for high light acclimation. PLANT & CELL PHYSIOLOGY 2012; 53:445-456. [PMID: 22210901 DOI: 10.1093/pcp/pcr190] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Nitric oxide (NO) has emerged as a fundamental signal molecule involved in the responses of plant to stress. A role for NO in the regulation of methionine sulfoxide reductase (MSR) mRNA expression and high light acclimation was studied in a green macroalga Ulva fasciata Delile. Transfer from darkness to high light (≥1,200 μmol photons m(-2) s(-1)) inhibited photosynthesis and growth but increased NO production and UfMSRA and UfMSRB transcripts. Treatment with an NO scavenger, 2-(4-carboxy- phenyl)-4,4,5,5-tetramethyl-imidazoline-1-oxyl-3-oxide (cPTIO), at 1,200 μmol photons m(-2) s(-1) caused a further growth inhibition accompanied by an inhibition of the increase of UfMSRA and UfMSRB transcripts by high light, while treatment with an NO generator, sodium nitroprusside (SNP), alleviated the growth inhibition and enhanced UfMSRA and UfMSRB expression. Exposure to moderate light (300 μmol photons m(-2) s(-1)) conditions also increased UfMSRA and UfMSRB transcripts, which were not affected by cPTIO treatment but were enhanced by SNP treatment. So, NO does not mediate the up-regulation of UfMSR genes by transfer to moderate light possibly as a precautionary mechanism in the sense of increasing light intensities in the daytime. In conclusion, NO production can be induced in U. fasciata upon exposure to high light for up-regulation of UfMSRA and UfMSRB expression but the level of NO production is not sufficient for acquisition of full tolerance to high light stress. Enhanced NO production by an exogenously applied NO generator can effectively trigger the high light acclimation process, including UfMSRA and UfMSRB expression.
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Affiliation(s)
- Yuan-Ting Hsu
- Institute of Marine Biology, National Sun Yat-sen University, Kaohsiung 80424, Taiwan
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Thamatrakoln K, Korenovska O, Niheu AK, Bidle KD. Whole-genome expression analysis reveals a role for death-related genes in stress acclimation of the diatom Thalassiosira pseudonana. Environ Microbiol 2011; 14:67-81. [DOI: 10.1111/j.1462-2920.2011.02468.x] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
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29
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Shikata T, Iseki M, Matsunaga S, Higashi SI, Kamei Y, Watanabe M. Blue and Red Light-Induced Germination of Resting Spores in the Red-Tide Diatom Leptocylindrus danicus†. Photochem Photobiol 2011; 87:590-7. [DOI: 10.1111/j.1751-1097.2011.00914.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
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30
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Foresi N, Correa-Aragunde N, Parisi G, Caló G, Salerno G, Lamattina L. Characterization of a nitric oxide synthase from the plant kingdom: NO generation from the green alga Ostreococcus tauri is light irradiance and growth phase dependent. THE PLANT CELL 2010; 22:3816-3830. [PMID: 21119059 DOI: 10.1105/tpc.109.07351] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
The search for a nitric oxide synthase (NOS) sequence in the plant kingdom yielded two sequences from the recently published genomes of two green algae species of the Ostreococcus genus, O. tauri and O. lucimarinus. In this study, we characterized the sequence, protein structure, phylogeny, biochemistry, and expression of NOS from O. tauri. The amino acid sequence of O. tauri NOS was found to be 45% similar to that of human NOS. Folding assignment methods showed that O. tauri NOS can fold as the human endothelial NOS isoform. Phylogenetic analysis revealed that O. tauri NOS clusters together with putative NOS sequences of a Synechoccocus sp strain and Physarum polycephalum. This cluster appears as an outgroup of NOS representatives from metazoa. Purified recombinant O. tauri NOS has a K(m) for the substrate l-Arg of 12 ± 5 μM. Escherichia coli cells expressing recombinant O. tauri NOS have increased levels of NO and cell viability. O. tauri cultures in the exponential growth phase produce 3-fold more NOS-dependent NO than do those in the stationary phase. In O. tauri, NO production increases in high intensity light irradiation and upon addition of l-Arg, suggesting a link between NOS activity and microalgal physiology.
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Affiliation(s)
- Noelia Foresi
- Instituto de Investigaciones Biológicas, Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Mar del Plata, 7600 Mar del Plata, Argentina
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31
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Foresi N, Correa-Aragunde N, Parisi G, Caló G, Salerno G, Lamattina L. Characterization of a nitric oxide synthase from the plant kingdom: NO generation from the green alga Ostreococcus tauri is light irradiance and growth phase dependent. THE PLANT CELL 2010; 22:3816-30. [PMID: 21119059 PMCID: PMC3015112 DOI: 10.1105/tpc.109.073510] [Citation(s) in RCA: 188] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/15/2009] [Revised: 09/17/2010] [Accepted: 11/09/2010] [Indexed: 05/18/2023]
Abstract
The search for a nitric oxide synthase (NOS) sequence in the plant kingdom yielded two sequences from the recently published genomes of two green algae species of the Ostreococcus genus, O. tauri and O. lucimarinus. In this study, we characterized the sequence, protein structure, phylogeny, biochemistry, and expression of NOS from O. tauri. The amino acid sequence of O. tauri NOS was found to be 45% similar to that of human NOS. Folding assignment methods showed that O. tauri NOS can fold as the human endothelial NOS isoform. Phylogenetic analysis revealed that O. tauri NOS clusters together with putative NOS sequences of a Synechoccocus sp strain and Physarum polycephalum. This cluster appears as an outgroup of NOS representatives from metazoa. Purified recombinant O. tauri NOS has a K(m) for the substrate l-Arg of 12 ± 5 μM. Escherichia coli cells expressing recombinant O. tauri NOS have increased levels of NO and cell viability. O. tauri cultures in the exponential growth phase produce 3-fold more NOS-dependent NO than do those in the stationary phase. In O. tauri, NO production increases in high intensity light irradiation and upon addition of l-Arg, suggesting a link between NOS activity and microalgal physiology.
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Affiliation(s)
- Noelia Foresi
- Instituto de Investigaciones Biológicas, Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Mar del Plata, 7600 Mar del Plata, Argentina
| | - Natalia Correa-Aragunde
- Instituto de Investigaciones Biológicas, Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Mar del Plata, 7600 Mar del Plata, Argentina
| | - Gustavo Parisi
- Centro de Estudios e Investigaciones, Universidad Nacional de Quilmes, Sáenz Peña 180, B1876BXD Bernal, Argentina
| | - Gonzalo Caló
- Centro de Investigaciones Biológicas and Centro de Estudios de Biodiversidad y Biotecnología de Mar del Plata, Fundación para Investigaciones Biológicas Aplicadas, 7600 Mar del Plata, Argentina
| | - Graciela Salerno
- Centro de Investigaciones Biológicas and Centro de Estudios de Biodiversidad y Biotecnología de Mar del Plata, Fundación para Investigaciones Biológicas Aplicadas, 7600 Mar del Plata, Argentina
| | - Lorenzo Lamattina
- Instituto de Investigaciones Biológicas, Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Mar del Plata, 7600 Mar del Plata, Argentina
- Address correspondence to
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Nedelcu AM, Driscoll WW, Durand PM, Herron MD, Rashidi A. On the paradigm of altruistic suicide in the unicellular world. Evolution 2010; 65:3-20. [PMID: 20722725 DOI: 10.1111/j.1558-5646.2010.01103.x] [Citation(s) in RCA: 84] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Altruistic suicide is best known in the context of programmed cell death (PCD) in multicellular individuals, which is understood as an adaptive process that contributes to the development and functionality of the organism. After the realization that PCD-like processes can also be induced in single-celled lineages, the paradigm of altruistic cell death has been extended to include these active cell death processes in unicellular organisms. Here, we critically evaluate the current conceptual framework and the experimental data used to support the notion of altruistic suicide in unicellular lineages, and propose new perspectives. We argue that importing the paradigm of altruistic cell death from multicellular organisms to explain active death in unicellular lineages has the potential to limit the types of questions we ask, thus biasing our understanding of the nature, origin, and maintenance of this trait. We also emphasize the need to distinguish between the benefits and the adaptive role of a trait. Lastly, we provide an alternative framework that allows for the possibility that active death in single-celled organisms is a maladaptive trait maintained as a byproduct of selection on pro-survival functions, but that could-under conditions in which kin/group selection can act-be co-opted into an altruistic trait.
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Affiliation(s)
- Aurora M Nedelcu
- University of New Brunswick, Department of Biology, Fredericton, NB, Canada.
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Bowler C, Vardi A, Allen AE. Oceanographic and biogeochemical insights from diatom genomes. ANNUAL REVIEW OF MARINE SCIENCE 2010; 2:333-65. [PMID: 21141668 DOI: 10.1146/annurev-marine-120308-081051] [Citation(s) in RCA: 125] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Diatoms are the most successful group of eukaryotic phytoplankton in the modern ocean and have risen to dominance relatively quickly over the last 100 million years. Recently completed whole genome sequences from two species of diatom, Thalassiosira pseudonana and Phaeodactylum tricornutum, have revealed a wealth of information about the evolutionary origins and metabolic adaptations that have led to their ecological success. A major finding is that they have incorporated genes both from their endosymbiotic ancestors and by horizontal gene transfer from marine bacteria. This unique melting pot of genes encodes novel capacities for metabolic management, for example, allowing the integration of a urea cycle into a photosynthetic cell. In this review we show how genome-enabled approaches are being leveraged to explore major phenomena of oceanographic and biogeochemical relevance, such as nutrient assimilation and life histories in diatoms. We also discuss how diatoms may be affected by climate change-induced alterations in ocean processes.
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Affiliation(s)
- Chris Bowler
- CNRS UMR8186, Department of Biology, Ecole Normale Supérieure, Paris, France.
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Délano-Frier JP, Estrada-Hernández MG. Bemisia tabaci-infested tomato plants show a phase-specific pattern of photosynthetic gene expression indicative of disrupted electron flow leading to photo-oxidation and plant death. PLANT SIGNALING & BEHAVIOR 2009; 4:992-995. [PMID: 19826216 PMCID: PMC2801371 DOI: 10.4161/psb.4.10.9663] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/29/2009] [Accepted: 07/30/2009] [Indexed: 05/28/2023]
Abstract
A suppression-subtractive-hybridization (SSH) strategy led to the identification of several genes whose expression was differentially modified in response to different larval phases present during the infestation process of tomato plants (Solanum lycopersicum) by virus-free whitefly Bemisia tabaci (Bt). The findings regarding photosynthetic gene expression were in accordance to previous studies reporting altered patterns of expression as a result of insect herbivory. However, the examination, in this study, of four stages of larval Bt development permitted the detection of phase-dependent changes in gene expression which appeared to target specific photosynthetic complexes. Thus, an upregulation of photosystem II genes in the latter two phases of Bt development contrasted with a general repression of genes belonging to the three other photosynthetic complexes, in addition to a number of genes coding for proteins associated with the oxygen evolving complex and the Calvin cycle. We propose that the contrasting pattern of expression led to an over-excitation of PSII and consequent oxidative damage, as suggested by the concomitant upregulation of oxidative stress genes, and could have contributed to the wide-spread necrosis observed in Bt-infested tomato plants at late stages of the plant-insect interaction.
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Affiliation(s)
- John Paul Délano-Frier
- Unidad de Biotecnología e Ingeniería Genética de Plantas, (Cinvestav-Campus Guanajuato), Km 9.6 del Libramiento Norte Carretera Irapuato-León, Irapuato, Gto., México.
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Abstract
Two genome sequences of diatoms, marine single-celled photosynthetic eukaryotes that often have ornate cell walls, give insights into their metabolic and signaling systems. The results of two published genome sequences from marine diatoms provide basic insights into how these remarkable organisms evolved to become one of the most successful groups of eukaryotic algae in the contemporary ocean.
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Affiliation(s)
- Assaf Vardi
- Environmental Biophysics and Molecular Ecology Program, Institute of Marine and Coastal Sciences, Rutgers University, New Brunswick, NJ 08540, USA
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