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Larson AG, Chajwa R, Li H, Prakash M. Inflation-induced motility for long-distance vertical migration. Curr Biol 2024; 34:5149-5163.e3. [PMID: 39423814 DOI: 10.1016/j.cub.2024.09.046] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2024] [Revised: 06/26/2024] [Accepted: 09/17/2024] [Indexed: 10/21/2024]
Abstract
The vertical migrations of pelagic organisms play a crucial role in shaping marine ecosystems and influencing global biogeochemical cycles. They also form the foundation of what might be the largest daily biomass movement on Earth. Surprisingly, among this diverse group of organisms, some single-cell protists can transit depths exceeding 50 m without employing flagella or cilia. How these non-motile cells perform large migrations remains unknown. It has been previously proposed that this capability might rely on the cell's ability to regulate its internal density relative to seawater. Here, using the dinoflagellate algae Pyrocystis noctiluca as a model system, we discover a rapid cell inflation event post cell division, during which a single plankton cell expands its volume 6-fold in less than 10 min. We demonstrate this rapid cellular inflation is the primary mechanism of density control. This self-regulated cellular inflation selectively imports fluid less dense than surrounding seawater and can thus effectively sling-shot a cell and reverse sedimentation within minutes. To accommodate its dramatic cellular expansion, Pyrocystis noctiluca possesses a unique reticulated cytoplasmic architecture that enables a rapid increase in overall cell volume without diluting its cytoplasmic content. We further present a generalized mathematical framework that unifies cell-cycle-driven density regulation, stratified ecology, and associated cell behavior in the open ocean. Our study unveils an ingenious strategy employed by a non-motile plankton to evade the gravitational sedimentation trap, highlighting how precise control of cell size and cell density can enable long-distance migration in the open ocean.
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Affiliation(s)
- Adam G Larson
- Department of Bioengineering, Stanford University, Stanford, CA 94305, USA
| | - Rahul Chajwa
- Department of Bioengineering, Stanford University, Stanford, CA 94305, USA
| | - Hongquan Li
- Department of Bioengineering, Stanford University, Stanford, CA 94305, USA
| | - Manu Prakash
- Department of Bioengineering, Stanford University, Stanford, CA 94305, USA; Department of Biology, Stanford University, Stanford, CA 94305, USA; Department of Ocean, Stanford University, Stanford, CA 94305, USA; Woods Institute of the Environment, Stanford University, Stanford, CA 94305, USA.
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2
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Tian X, Wang Y, Xu T, Guo Y, Bi Y, Liu Y, Liang Y, Cui W, Liu Y, Hu L, Yin Y, Cai Y, Jiang G. Bioconcentration of Inorganic and Methyl Mercury by Algae Revealed Using Dual-Mass Single-Cell ICP-MS with Double Isotope Tracers. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2024; 58:7860-7869. [PMID: 38647522 DOI: 10.1021/acs.est.3c10884] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/25/2024]
Abstract
Algae are an entry point for mercury (Hg) into the food web. Bioconcentration of Hg by algae is crucial for its biogeochemical cycling and environmental risk. Herein, considering the cell heterogeneity, we investigated the bioconcentration of coexisting isotope-labeled inorganic (199IHg) and methyl Hg (201MeHg) by six typical freshwater and marine algae using dual-mass single-cell inductively coupled plasma mass spectrometry (scICP-MS). First, a universal pretreatment procedure for the scICP-MS analysis of algae was developed. Using the proposed method, the intra- and interspecies heterogeneities and the kinetics of Hg bioconcentration by algae were revealed at the single-cell level. The heterogeneity in the cellular Hg contents is largely related to cell size. The bioconcentration process reached a dynamic equilibrium involving influx/adsorption and efflux/desorption within hours. Algal density is a key factor affecting the distribution of Hg between algae and ambient water. Cellular Hg contents were negatively correlated with algal density, whereas the volume concentration factors almost remained constant. Accordingly, we developed a model based on single-cell analysis that well describes the density-driven effects of Hg bioconcentration by algae. From a novel single-cell perspective, the findings improve our understanding of algal bioconcentration governed by various biological and environmental factors.
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Affiliation(s)
- Xiangwei Tian
- Laboratory of Environmental Nanotechnology and Health Effect, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China
- State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China
- University of Chinese Academy of Sciences (UCAS), Beijing 100049, China
| | - Ying Wang
- Institute of Environment and Health, Hangzhou Institute for Advanced Study, UCAS, Hangzhou 310024, China
| | - Tao Xu
- Institute of Environment and Health, Hangzhou Institute for Advanced Study, UCAS, Hangzhou 310024, China
| | - Yingying Guo
- Laboratory of Environmental Nanotechnology and Health Effect, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China
- State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China
| | - Yonghong Bi
- State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, China
| | - Yanqun Liu
- School of Medicine, Jianghan University, Wuhan 430056, China
- Hubei Key Laboratory of Environmental and Health Effects of Persistent Toxic Substances, School of Environment and Health, Jianghan University, Wuhan 430056, China
| | - Yong Liang
- Hubei Key Laboratory of Environmental and Health Effects of Persistent Toxic Substances, School of Environment and Health, Jianghan University, Wuhan 430056, China
| | - Wenbin Cui
- R&D Center, Shandong Yingsheng Biotechnology Co., Ltd., Beijing 100088, China
| | - Yanwei Liu
- Laboratory of Environmental Nanotechnology and Health Effect, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China
- State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China
| | - Ligang Hu
- State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China
| | - Yongguang Yin
- Laboratory of Environmental Nanotechnology and Health Effect, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China
- State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China
- University of Chinese Academy of Sciences (UCAS), Beijing 100049, China
- Institute of Environment and Health, Hangzhou Institute for Advanced Study, UCAS, Hangzhou 310024, China
- Hubei Key Laboratory of Environmental and Health Effects of Persistent Toxic Substances, School of Environment and Health, Jianghan University, Wuhan 430056, China
| | - Yong Cai
- Laboratory of Environmental Nanotechnology and Health Effect, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China
- State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China
- Department of Chemistry and Biochemistry, Florida International University, Miami, Florida 33199, United States
| | - Guibin Jiang
- State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China
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Petrucciani A, Moretti P, Ortore MG, Norici A. Integrative effects of morphology, silicification, and light on diatom vertical movements. FRONTIERS IN PLANT SCIENCE 2023; 14:1143998. [PMID: 37056507 PMCID: PMC10087530 DOI: 10.3389/fpls.2023.1143998] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/13/2023] [Accepted: 03/06/2023] [Indexed: 06/19/2023]
Abstract
Diatoms represent the most abundant and diversified class of primary producers in present oceans; their distinctive trait is the ability to incorporate silicic acid in a silica outer shell called frustule. Numerous adaptative functions are ascribed to frustules, including the control of vertical movements through the water column; this indirectly determines cell access to fundamental resources such as light and nutrients, and favors diatom escape from predators. At the same time, light guides phototroph movements in the water column by affecting cell density (e.g., by modulating Si deposition in diatoms, vacuole volume, and/or solution). We investigated how the tremendous diversity in morphology and silicification that characterizes the frustule and the crucial role of light in diatom spatial distribution govern diatom sinking capacity. To test their integrative effects, we acclimated four diatoms distinguished by frustule traits (Chaetoceros muelleri, Conticribra weissflogii, Phaeodactylum tricornutum, and Cylindrotheca fusiformis) to different light conditions and evaluated their physiological performance in terms of growth, elemental composition, morphological changes, and their in vivo sinking capacity. What emerged from this study was that silicification, more than other morphological characteristics, controls species vertical movements, while a higher energy availability enhances cell floating independently from the silica content.
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Lynch M, Schavemaker PE, Licknack TJ, Hao Y, Pezzano A. Evolutionary bioenergetics of ciliates. J Eukaryot Microbiol 2022; 69:e12934. [PMID: 35778890 PMCID: PMC11336482 DOI: 10.1111/jeu.12934] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2022] [Revised: 05/23/2022] [Accepted: 06/08/2022] [Indexed: 10/17/2022]
Abstract
Understanding why various organisms evolve alternative ways of living requires information on both the fitness advantages of phenotypic modifications and the costs of constructing and operating cellular features. Although the former has been the subject of a myriad of ecological studies, almost no attention has been given to how organisms allocate resources to alternative structures and functions. We address these matters by capitalizing on an array of observations on diverse ciliate species and from the emerging field of evolutionary bioenergetics. A relatively robust and general estimator for the total cost of a cell per cell cycle (in units of ATP equivalents) is provided, and this is then used to understand how the magnitudes of various investments scale with cell size. Among other things, we examine the costs associated with the large macronuclear genomes of ciliates, as well as ribosomes, various internal membranes, osmoregulation, cilia, and swimming activities. Although a number of uncertainties remain, the general approach taken may serve as blueprint for expanding this line of work to additional traits and phylogenetic lineages.
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Affiliation(s)
- Michael Lynch
- Biodesign Center for Mechanisms of Evolution, Arizona State University, Tempe, Arizona, USA
| | - Paul E. Schavemaker
- Biodesign Center for Mechanisms of Evolution, Arizona State University, Tempe, Arizona, USA
| | - Timothy J. Licknack
- Biodesign Center for Mechanisms of Evolution, Arizona State University, Tempe, Arizona, USA
| | - Yue Hao
- Biodesign Center for Mechanisms of Evolution, Arizona State University, Tempe, Arizona, USA
| | - Arianna Pezzano
- Ira A. Fulton Schools of Engineering, School of Biological and Health Systems Engineering, Arizona State University, Tempe, Arizona, USA
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Evolution of Phytoplankton in Relation to Their Physiological Traits. JOURNAL OF MARINE SCIENCE AND ENGINEERING 2022. [DOI: 10.3390/jmse10020194] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Defining the physiological traits that characterise phytoplankton involves comparison with related organisms in benthic habitats. Comparison of survival time in darkness under natural conditions requires more information. Gas vesicles and flagella as mechanisms of upward movement relative to surrounding water, allowing periodic vertical migration, are not confined to plankton, although buoyancy changes related to compositional changes of a large central vacuole may be restricted to plankton. Benthic microalgae have the same range of photosynthetic pigments as phytoplankton; it is not clear if there are differences in the rate of regulation and acclimation of photosynthetic machinery to variations in irradiance for phytoplankton and for microphytobenthos. There are inadequate data to determine if responses to variations in frequency or magnitude of changes in the supply of inorganic carbon, nitrogen or phosphorus differ between phytoplankton and benthic microalgae. Phagophotomixotrophy and osmophotomixotrophy occur in both phytoplankton and benthic microalgae. Further progress in identifying physiological traits specific to phytoplankton requires more experimentation on benthic microalgae that are closely related to planktonic microalgae, with attention to whether the benthic algae examined have, as far as can be determined, never been planktonic during their evolution or are derived from planktonic ancestors.
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Hamano R, Shoumura S, Takeda Y, Yamazaki T, Hirayama K, Hanada Y, Mayama S, Takemura M, Lin HJ, Umemura K. Sinking of Four Species of Living Diatom Cells Directly Observed by a "Tumbled" Optical Microscope. MICROSCOPY AND MICROANALYSIS : THE OFFICIAL JOURNAL OF MICROSCOPY SOCIETY OF AMERICA, MICROBEAM ANALYSIS SOCIETY, MICROSCOPICAL SOCIETY OF CANADA 2021; 27:1-7. [PMID: 34294188 DOI: 10.1017/s1431927621012150] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
The study of the sinking phenomenon of diatom cells, which have a slightly larger specific gravity (~1.3) compared to that of water, is an important research topic for understanding photosynthetic efficiency. In this study, we successfully demonstrated the observation of the sinking behaviors of four different species of diatom using a homemade “tumbled” optical microscope. A homemade 1 mm3 microchamber was employed to decrease the effects of convection currents. In the microchamber, diatom cells were basically settled in a linear manner without floating, although some of the cells were rotated during their sinking. Sinking speeds of the four species of diatom cells, Nitzschia sp., Pheodactylum tricornutum, Navicula sp., and Odontella aurita, were 0.81 ± 5.56, 3.03 ± 10.17, 3.29 ± 7.39, and 11.22 ± 21.42 μm/s, respectively, based on the automatic tracking analysis of the centroids of each cell. Manual analysis of a vector between two longitudinal ends of the cells (two-point analysis) was effective for quantitatively characterizing the rotation phenomenon; therefore, angles and angular velocities of rotating cells were well determined as a function of time. The effects of the cell shapes on sinking velocity could be explained by simulation analysis using the modified Stokes’ law proposed by Miklasz et al.
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Affiliation(s)
- Ryo Hamano
- Department of Physics, Tokyo University of Science, 1-3 Kagurazaka, Shinjuku, Tokyo162-8601, Japan
| | - Shingo Shoumura
- Department of Physics, Tokyo University of Science, 1-3 Kagurazaka, Shinjuku, Tokyo162-8601, Japan
| | - Yuto Takeda
- Department of Physics, Tokyo University of Science, 1-3 Kagurazaka, Shinjuku, Tokyo162-8601, Japan
| | - Tokio Yamazaki
- Department of Physics, Tokyo University of Science, 1-3 Kagurazaka, Shinjuku, Tokyo162-8601, Japan
| | - Kota Hirayama
- Department of Physics, Tokyo University of Science, 1-3 Kagurazaka, Shinjuku, Tokyo162-8601, Japan
| | - Yasutaka Hanada
- Graduate School of Science and Technology, Hirosaki University, 3 Bunkyo-cho, Hirosaki, Aomori036-8561, Japan
| | - Shigeki Mayama
- Advanced Support Center for Science Teachers, Tokyo Gakugei University, 4-1-1 Nukui-kita-machi, Koganei, Tokyo184-8511, Japan
| | - Masaharu Takemura
- Laboratory of Biology, Institute of Arts and Sciences, Tokyo University of Science, 1-3 Kagurazaka, Shinjuku, Tokyo162-8601, Japan
| | - Han-Jia Lin
- Department of Bioscience and Biotechnology, Center of Excellence for the Oceans, National Taiwan Ocean University, Keelung20224, Taiwan
| | - Kazuo Umemura
- Department of Physics, Tokyo University of Science, 1-3 Kagurazaka, Shinjuku, Tokyo162-8601, Japan
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7
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Tyerman SD, McGaughey SA, Qiu J, Yool AJ, Byrt CS. Adaptable and Multifunctional Ion-Conducting Aquaporins. ANNUAL REVIEW OF PLANT BIOLOGY 2021; 72:703-736. [PMID: 33577345 DOI: 10.1146/annurev-arplant-081720-013608] [Citation(s) in RCA: 43] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Aquaporins function as water and neutral solute channels, signaling hubs, disease virulence factors, and metabolon components. We consider plant aquaporins that transport ions compared to some animal counterparts. These are candidates for important, as yet unidentified, cation and anion channels in plasma, tonoplast, and symbiotic membranes. For those individual isoforms that transport ions, water, and gases, the permeability spans 12 orders of magnitude. This requires tight regulation of selectivity via protein interactions and posttranslational modifications. A phosphorylation-dependent switch between ion and water permeation in AtPIP2;1 might be explained by coupling between the gates of the four monomer water channels and the central pore of the tetramer. We consider the potential for coupling between ion and water fluxes that could form the basis of an electroosmotic transducer. A grand challenge in understanding the roles of ion transporting aquaporins is their multifunctional modes that are dependent on location, stress, time, and development.
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Affiliation(s)
- Stephen D Tyerman
- Australian Research Council (ARC) Centre of Excellence in Plant Energy Biology, School of Agriculture, Food and Wine, University of Adelaide, Glen Osmond, South Australia 5064, Australia; ,
| | - Samantha A McGaughey
- ARC Centre of Excellence for Translational Photosynthesis, Division of Plant Sciences, Research School of Biology, Australian National University, Acton, Australian Capital Territory 0200, Australia; ,
| | - Jiaen Qiu
- Australian Research Council (ARC) Centre of Excellence in Plant Energy Biology, School of Agriculture, Food and Wine, University of Adelaide, Glen Osmond, South Australia 5064, Australia; ,
| | - Andrea J Yool
- Adelaide Medical School, University of Adelaide, Adelaide, South Australia 5005, Australia;
| | - Caitlin S Byrt
- ARC Centre of Excellence for Translational Photosynthesis, Division of Plant Sciences, Research School of Biology, Australian National University, Acton, Australian Capital Territory 0200, Australia; ,
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8
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Behrenfeld MJ, Halsey KH, Boss E, Karp‐Boss L, Milligan AJ, Peers G. Thoughts on the evolution and ecological niche of diatoms. ECOL MONOGR 2021. [DOI: 10.1002/ecm.1457] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Affiliation(s)
- Michael J. Behrenfeld
- Department of Botany and Plant Pathology Oregon State University 4575 SW Research Way Corvallis Oregon 97333 USA
| | - Kimberly H. Halsey
- Department of Microbiology Oregon State University Nash Hall 226 Corvallis Oregon 97331 USA
| | - Emmanuel Boss
- School of Marine Sciences University of Maine 5706 Aubert Hall Orono Maine 04469‐5706 USA
| | - Lee Karp‐Boss
- School of Marine Sciences University of Maine 5706 Aubert Hall Orono Maine 04469‐5706 USA
| | - Allen J. Milligan
- Department of Botany and Plant Pathology Oregon State University 4575 SW Research Way Corvallis Oregon 97333 USA
| | - Graham Peers
- Department of Biology Colorado State University Biology Building, Room 111, 1878 Campus Delivery Fort Collins Colorado 80523‐1878 USA
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Vitali V, Sutka M, Ojeda L, Aroca R, Amodeo G. Root hydraulics adjustment is governed by a dominant cell-to-cell pathway in Beta vulgaris seedlings exposed to salt stress. PLANT SCIENCE : AN INTERNATIONAL JOURNAL OF EXPERIMENTAL PLANT BIOLOGY 2021; 306:110873. [PMID: 33775369 DOI: 10.1016/j.plantsci.2021.110873] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/02/2020] [Revised: 02/27/2021] [Accepted: 03/02/2021] [Indexed: 06/12/2023]
Abstract
Soil salinity reduces root hydraulic conductivity (Lpr) of several plant species. However, how cellular signaling and root hydraulic properties are linked in plants that can cope with water restriction remains unclear. In this work, we exposed the halotolerant species red beet (Beta vulgaris) to increasing concentrations of NaCl to determine the components that might be critical to sustaining the capacity to adjust root hydraulics. Our strategy was to use both hydraulic and cellular approaches in hydroponically grown seedlings during the first osmotic phase of salt stress. Interestingly, Lpr presented a bimodal profile response apart from the magnitude of the imposed salt stress. As well as Lpr, the PIP2-aquaporin profile follows an unphosphorylated/phosphorylated pattern when increasing NaCl concentration while PIP1 aquaporins remain constant. Lpr also shows high sensitivity to cycloheximide. In low NaCl concentrations, Lpr was high and 70 % of its capacity could be attributed to the CHX-inhibited cell-to-cell pathway. More interestingly, roots can maintain a constant spontaneous exudated flow that is independent of the applied NaCl concentration. In conclusion, Beta vulgaris root hydraulic adjustment completely lies in a dominant cell-to-cell pathway that contributes to satisfying plant water demands.
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Affiliation(s)
- Victoria Vitali
- Departamento de Biodiversidad y Biología Experimental, Facultad de Ciencias Exactas y Naturales & Instituto de Biodiversidad, Biología Experimental y Aplicada, Universidad de Buenos Aires and Consejo Nacional de Investigaciones Científicas y Técnicas, C1428EGA, Buenos Aires, Argentina
| | - Moira Sutka
- Departamento de Biodiversidad y Biología Experimental, Facultad de Ciencias Exactas y Naturales & Instituto de Biodiversidad, Biología Experimental y Aplicada, Universidad de Buenos Aires and Consejo Nacional de Investigaciones Científicas y Técnicas, C1428EGA, Buenos Aires, Argentina
| | - Lucas Ojeda
- Departamento de Biodiversidad y Biología Experimental, Facultad de Ciencias Exactas y Naturales & Instituto de Biodiversidad, Biología Experimental y Aplicada, Universidad de Buenos Aires and Consejo Nacional de Investigaciones Científicas y Técnicas, C1428EGA, Buenos Aires, Argentina
| | - Ricardo Aroca
- Departamento de Microbiología del Suelo y Sistemas Simbióticos, Estación Experimental del Zaidín (EEZ-CSIC), Profesor Albareda 1, 18008, Granada, Spain
| | - Gabriela Amodeo
- Departamento de Biodiversidad y Biología Experimental, Facultad de Ciencias Exactas y Naturales & Instituto de Biodiversidad, Biología Experimental y Aplicada, Universidad de Buenos Aires and Consejo Nacional de Investigaciones Científicas y Técnicas, C1428EGA, Buenos Aires, Argentina.
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10
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Raven JA. Determinants, and implications, of the shape and size of thylakoids and cristae. JOURNAL OF PLANT PHYSIOLOGY 2021; 257:153342. [PMID: 33385618 DOI: 10.1016/j.jplph.2020.153342] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/02/2020] [Revised: 11/25/2020] [Accepted: 12/08/2020] [Indexed: 06/12/2023]
Abstract
Thylakoids are flattened sacs isolated from other membranes; cristae are attached to the rest of the inner mitochondrial membrane by the crista junction, but the crista lumen is separated from the intermembrane space. The shape of thylakoids and cristae involves membranes with small (5-30 nm) radii of curvature. While the mechanism of curvature is not entirely clear, it seems to be largely a function of Curt proteins in thylakoids and Mitochondrial Organising Site and Crista Organising Centre proteins and oligomeric FOF1 ATP synthase in cristae. A subordinate, or minimal, role is attributable to lipids with areas of their head group area greater (convex leaflet) or smaller (concave leaflet) than the area of the lipid tail; examples of the latter group are monogalactosyldiglyceride in thylakoids and cardiolipin in cristae. The volume per unit area on the lumen side of the membrane is less than that of the chloroplast stroma or cyanobacterial cytosol for thylakoids, and mitochondrial matrix for cristae. A low volume per unit area of thylakoids and cristae means a small lumen width that is the average of wider spaces between lipid parts of the membranes and the narrower gaps dominated by extra-membrane components of transmembrane proteins. These structural constraints have important implications for the movement of the electron carriers plastocyanin and cytochrome c6 (thylakoids) and cytochrome c (cristae) and hence the separation of the membrane-associated electron donors to, and electron acceptors from, these water-soluble electron carriers. The donor/acceptor pairs, are the cytochrome fb6Fenh complex and P700+ in thylakoids, and Complex III and Complex IV of cristae. The other energy flux parallel to the membranes is that of the proton motive force generated by redox-powered H+ pumps into the lumen to the proton motive force use in ATP synthesis by H+ flux from the lumen through the ATP synthase. For both the electron transport and proton motive force movement, concentration differences of reduced and oxidised electron carriers and protonated and deprotonated pH buffers are involved. The need for diffusion along a congested route of these energy transfer agents may limit the separation of sources and sinks parallel to the membranes of thylakoids and cristae.
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Affiliation(s)
- John A Raven
- Division of Plant Science, University of Dundee at the James Hutton Institute, Invergowrie, Dundee, DD2 5DA, UK; University of Technology, Sydney, Climate Change Cluster, Faculty of Science, Sydney, Ultimo, NSW, 2007, Australia; School of Biological Sciences, University of Western Australia, Crawley, WA, 6009, Australia.
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11
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Raven JA. Chloride involvement in the synthesis, functioning and repair of the photosynthetic apparatus in vivo. THE NEW PHYTOLOGIST 2020; 227:334-342. [PMID: 32170958 DOI: 10.1111/nph.16541] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/04/2020] [Accepted: 03/05/2020] [Indexed: 06/10/2023]
Abstract
Cl- has long been known as a micronutrient for oxygenic photosynthetic resulting from its role an essential cofactor for photosystem II (PSII). Evidence on the in vivo Cl- distribution in Spinacia oleracea leaves and chloroplasts shows that sufficient Cl- is present for the involvement in PSII function, as indicated by in vitro studies on, among other organisms, S. oleracea PsII. There is also sufficient Cl- to function, with K+ , in parsing the H+ electrochemical potential difference (proton motive force) across the illuminated thylakoid membrane into electrical potential difference and pH difference components. However, recent in vitro work on PSII from S. oleracea shows that oxygen evolving complex (OEC) synthesis, and resynthesis after photodamage, requires significantly higher Cl- concentrations than would satisfy the function of assembled PSII O2 evolution of the synthesised PSII with the OEC. The low Cl- affinity of OEC (re-)assembly could be a component limiting the rate of OEC (re-)assembly.
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Affiliation(s)
- John A Raven
- Division of Plant Sciences, University of Dundee at the James Hutton Institute, Invergowrie, Dundee, DD2 5DA, UK
- Climate Change Cluster, University of Technology, Ultimo, Sydney, NSW, 2007, Australia
- School of Biological Science, University of Western Australia, 35 Stirling Highway, Crawley, WA, 6009, Australia
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12
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Lavoie M, Raven JA. How can large-celled diatoms rapidly modulate sinking rates episodically? JOURNAL OF EXPERIMENTAL BOTANY 2020; 71:3386-3389. [PMID: 32161972 PMCID: PMC7364400 DOI: 10.1093/jxb/eraa129] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/11/2019] [Accepted: 03/07/2020] [Indexed: 06/10/2023]
Affiliation(s)
- Michel Lavoie
- Québec-Océan and Unité Mixte Internationale Takuvik Ulaval-CNRS, Département de Biologie, Université Laval, Québec-Océan, Québec, Canada
| | - John A Raven
- Division of Plant Science, University of Dundee, The James Hutton Institute, Invergowrie, Dundee, UK
- School of Biological Sciences, University of Western Australia, Crawley (Perth), WA, Australia
- Climate Changer Cluster, University of Technology Sydney, Ultimo, NSW, Australia
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13
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McParland EL, Wright A, Art K, He M, Levine NM. Evidence for contrasting roles of dimethylsulfoniopropionate production in Emiliania huxleyi and Thalassiosira oceanica. THE NEW PHYTOLOGIST 2020; 226:396-409. [PMID: 31850524 PMCID: PMC7154784 DOI: 10.1111/nph.16374] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/24/2019] [Accepted: 11/27/2019] [Indexed: 05/28/2023]
Abstract
Dimethylsulfoniopropionate (DMSP) is a globally abundant marine metabolite and a significant source of organic carbon and sulfur for marine microbial ecosystems with the potential to influence climate regulation. However, the physiological function of DMSP has remained enigmatic for >30 yr. Recent insight suggests that there are different physiological roles for DMSP based on the cellular DMSP concentrations in producers. Differential production of DMSP was tested with multiple physiological experiments that altered nitrate availability, salinity and temperature to create stressed growth and target different metabolic conditions in Emiliania huxleyi, a high DMSP producer and Thalassiosira oceanica, a low DMSP producer. Emiliania huxleyi intracellular DMSP did not respond to metabolically imbalanced conditions, while Thalassiosira oceanica intracellular DMSP was significantly correlated to stressed growth rate across all conditions tested and exhibited a plastic response on a timescale of hours in nonsteady-state. The previous assumption that proposed DMSP mechanism(s) can be universally applied to all producers is shown to be unlikely. Rather, two distinct ecological roles for DMSP likely exist that differ by producer type, where: (1) the primary role of DMSP in high producers is a constitutive compatible solute; and (2) DMSP production in low producers is a finely tuned stress response.
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Affiliation(s)
- Erin L. McParland
- Department of Marine Chemistry and GeochemistryWoods Hole Oceanographic InstitutionWoods HoleMA02543USA
- Department of Marine and Environmental BiologyUniversity of Southern CaliforniaLos AngelesCA90089USA
| | - Anna Wright
- Department of Marine and Environmental BiologyUniversity of Southern CaliforniaLos AngelesCA90089USA
| | - Kristin Art
- Department of Marine and Environmental BiologyUniversity of Southern CaliforniaLos AngelesCA90089USA
| | - Meagan He
- Department of Marine and Environmental BiologyUniversity of Southern CaliforniaLos AngelesCA90089USA
| | - Naomi M. Levine
- Department of Marine and Environmental BiologyUniversity of Southern CaliforniaLos AngelesCA90089USA
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Wegner LH, Shabala S. Biochemical pH clamp: the forgotten resource in membrane bioenergetics. THE NEW PHYTOLOGIST 2020; 225:37-47. [PMID: 31393010 DOI: 10.1111/nph.16094] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/07/2019] [Accepted: 08/01/2019] [Indexed: 05/08/2023]
Abstract
Solute uptake and release by plant cells are frequently energized by coupling to H+ influx supported by the proton motive force (pmf). The pmf results from a stable pH difference between the apoplast and the cytosol, with bulk values ranging from 4.9 to 5.8 and from 7.1 to 7.5, respectively, in combination with a negative electrical membrane potential. The P-type H+ ATPases pumping H+ from the cytosol into the apoplast at the expense of ATP hydrolysis are generally viewed as the only pmf source, exclusively linking membrane transport to energy metabolism. However, recent evidence suggests that pump activity may be insufficient to energize transport, particularly under stress conditions. Indeed, cytosolic H+ scavenging and apoplastic H+ generation by metabolism (denoted as 'active' buffering in contrast to the readily exhausted 'passive' matrix buffering) also stabilize the pH gradient. In the cytosol, H+ scavenging is mainly associated with malate decarboxylation catalyzed by malic enzyme, and via the GABA shunt of the tricarboxylic acid (TCA) cycle involving glutamate decarboxylation. In the apoplast, formation of bicarbonate from CO2 , the end-product of respiration, generates H+ at pH ≥ 6. Membrane potential is stabilized by K+ release and/or by anion uptake via ion channels. Finally, thermodynamic aspects of active buffering are discussed.
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Affiliation(s)
- Lars H Wegner
- International Research Centre for Environmental Membrane Biology, Foshan University, Foshan, 528041, China
| | - Sergey Shabala
- International Research Centre for Environmental Membrane Biology, Foshan University, Foshan, 528041, China
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15
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Du Clos KT, Karp-Boss L, Villareal TA, Gemmell BJ. Coscinodiscus wailesii mutes unsteady sinking in dark conditions. Biol Lett 2019; 15:20180816. [PMID: 30890072 DOI: 10.1098/rsbl.2018.0816] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Several species of large, centric diatoms exhibit an unsteady sinking behaviour characterized by order-of-magnitude oscillations in sinking speed that occur over seconds. We show that under nutrient-depleted conditions, Coscinodiscus wailesii exhibits significantly stronger unsteady sinking behaviour in the light than in the dark. Results suggest that regulating unsteady sinking in response to irradiance as well as nutrient conditions may help C. wailesii balance its requirements for light and nutrients, which are often spatially separated.
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Affiliation(s)
- Kevin T Du Clos
- 1 Department of Integrative Biology, University of South Florida , Tampa, FL 33620 , USA.,2 Marine Science Institute, University of Texas at Austin , Port Aransas, TX 78373 , USA
| | - Lee Karp-Boss
- 3 School of Marine Sciences, University of Maine , Orono, ME 04473 , USA
| | - Tracy A Villareal
- 2 Marine Science Institute, University of Texas at Austin , Port Aransas, TX 78373 , USA
| | - Brad J Gemmell
- 1 Department of Integrative Biology, University of South Florida , Tampa, FL 33620 , USA
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16
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Raven JA. The potential effect of low cell osmolarity on cell function through decreased concentration of enzyme substrates. JOURNAL OF EXPERIMENTAL BOTANY 2018; 69:4667-4673. [PMID: 29992331 DOI: 10.1093/jxb/ery254] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/11/2018] [Accepted: 07/03/2018] [Indexed: 06/08/2023]
Abstract
Some freshwater algae have lower (<130 osmol m-3) intracellular osmolarities than most others (>180 osmol m-3). Low osmolarities are related to the presence of flagella and the low energy cost of active water efflux following downhill water influx unconstrained by cell walls covering the plasmalemma, and the low resource cost of cell wall synthesis with the same mechanical degree of safety. One consequence of low intracellular osmolarity is limitation on the concentration of metabolites, that is, substrates and products of enzyme activity. Models of the flux through metabolic pathways, and hence the specific growth rate, using steady-state concentrations of enzymes and metabolites have involved organisms with intracellular metabolite osmolarities >280 osmol m-3, where the metabolite concentrations are much greater than the total osmolarity of some freshwater algae. Since the protein concentration (mol m-3) in the cells and the specific growth rates of freshwater cells with low and with higher intracellular osmolarity are highly similar, the models of trade-offs between enzyme and metabolite concentrations for cells with high intracellular osmolarity need modification for cells with low intracellular osmolarity. The soluble free-radical scavenger ascorbate can constitute as little as 0.2% of the low intracellular metabolite concentration (mol m-3) of low-intracellular-osmolarity cells.
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Affiliation(s)
- John A Raven
- Division of Plant Science, University of Dundee, The James Hutton Institute, Invergowrie, Dundee, UK
- School of Biological Sciences, University of Western Australia, Crawley (Perth), WA, Australia
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17
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Sánchez-Baracaldo P, Raven JA, Pisani D, Knoll AH. Early photosynthetic eukaryotes inhabited low-salinity habitats. Proc Natl Acad Sci U S A 2017; 114:E7737-E7745. [PMID: 28808007 PMCID: PMC5603991 DOI: 10.1073/pnas.1620089114] [Citation(s) in RCA: 148] [Impact Index Per Article: 21.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The early evolutionary history of the chloroplast lineage remains an open question. It is widely accepted that the endosymbiosis that established the chloroplast lineage in eukaryotes can be traced back to a single event, in which a cyanobacterium was incorporated into a protistan host. It is still unclear, however, which Cyanobacteria are most closely related to the chloroplast, when the plastid lineage first evolved, and in what habitats this endosymbiotic event occurred. We present phylogenomic and molecular clock analyses, including data from cyanobacterial and chloroplast genomes using a Bayesian approach, with the aim of estimating the age for the primary endosymbiotic event, the ages of crown groups for photosynthetic eukaryotes, and the independent incorporation of a cyanobacterial endosymbiont by Paulinella Our analyses include both broad taxon sampling (119 taxa) and 18 fossil calibrations across all Cyanobacteria and photosynthetic eukaryotes. Phylogenomic analyses support the hypothesis that the chloroplast lineage diverged from its closet relative Gloeomargarita, a basal cyanobacterial lineage, ∼2.1 billion y ago (Bya). Our analyses suggest that the Archaeplastida, consisting of glaucophytes, red algae, green algae, and land plants, share a common ancestor that lived ∼1.9 Bya. Whereas crown group Rhodophyta evolved in the Mesoproterozoic Era (1,600-1,000 Mya), crown groups Chlorophyta and Streptophyta began to radiate early in the Neoproterozoic (1,000-542 Mya). Stochastic mapping analyses indicate that the first endosymbiotic event occurred in low-salinity environments. Both red and green algae colonized marine environments early in their histories, with prasinophyte green phytoplankton diversifying 850-650 Mya.
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Affiliation(s)
| | - John A Raven
- Division of Plant Science, University of Dundee at the James Hutton Institute, Dundee DD2 5DA, United Kingdom
- Plant Functional Biology and Climate Change Cluster, University of Technology Sydney, Ultimo, NSW 2007, Australia
| | - Davide Pisani
- School of Biological Sciences, University of Bristol, Bristol BS8 1TH, United Kingdom
- School of Earth Sciences, University of Bristol, Bristol BS8 1TH, United Kingdom
| | - Andrew H Knoll
- Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA 02138
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18
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Groszmann M, Osborn HL, Evans JR. Carbon dioxide and water transport through plant aquaporins. PLANT, CELL & ENVIRONMENT 2017; 40:938-961. [PMID: 27739588 DOI: 10.1111/pce.12844] [Citation(s) in RCA: 73] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/19/2016] [Revised: 09/01/2016] [Accepted: 09/22/2016] [Indexed: 05/25/2023]
Abstract
Aquaporins are channel proteins that function to increase the permeability of biological membranes. In plants, aquaporins are encoded by multigene families that have undergone substantial diversification in land plants. The plasma membrane intrinsic proteins (PIPs) subfamily of aquaporins is of particular interest given their potential to improve plant water relations and photosynthesis. Flowering plants have between 7 and 28 PIP genes. Their expression varies with tissue and cell type, through development and in response to a variety of factors, contributing to the dynamic and tissue specific control of permeability. There are a growing number of PIPs shown to act as water channels, but those altering membrane permeability to CO2 are more limited. The structural basis for selective substrate specificities has not yet been resolved, although a few key amino acid positions have been identified. Several regions important for dimerization, gating and trafficking are also known. PIP aquaporins assemble as tetramers and their properties depend on the monomeric composition. PIPs control water flux into and out of veins and stomatal guard cells and also increase membrane permeability to CO2 in mesophyll and stomatal guard cells. The latter increases the effectiveness of Rubisco and can potentially influence transpiration efficiency.
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Affiliation(s)
- Michael Groszmann
- Australian Research Council Centre of Excellence for Translational Photosynthesis, Division of Plant Sciences, Research School of Biology, The Australian National University, Acton, ACT, 2601, Australia
| | - Hannah L Osborn
- Australian Research Council Centre of Excellence for Translational Photosynthesis, Division of Plant Sciences, Research School of Biology, The Australian National University, Acton, ACT, 2601, Australia
| | - John R Evans
- Australian Research Council Centre of Excellence for Translational Photosynthesis, Division of Plant Sciences, Research School of Biology, The Australian National University, Acton, ACT, 2601, Australia
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19
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Fricke W. Water transport and energy. PLANT, CELL & ENVIRONMENT 2017; 40:977-994. [PMID: 27756100 DOI: 10.1111/pce.12848] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/11/2016] [Revised: 10/08/2016] [Accepted: 10/10/2016] [Indexed: 05/10/2023]
Abstract
Water transport in plants occurs along various paths and is driven by gradients in its free energy. It is generally considered that the mode of transport, being either diffusion or bulk flow, is a passive process, although energy may be required to sustain the forces driving water flow. This review aims at putting water flow at the various organisational levels (cell, organ, plant) in the context of the energy that is required to maintain these flows. In addition, the question is addressed (1) whether water can be transported against a difference in its chemical free energy, 'water potential' (Ψ), through, directly or indirectly, active processes; and (2) whether the energy released when water is flowing down a gradient in its energy, for example during day-time transpiration and cell expansive growth, is significant compared to the energy budget of plant and cell. The overall aim of review is not so much to provide a definite 'Yes' and 'No' to these questions, but rather to stimulate discussion and raise awareness that water transport in plants has its real, associated, energy costs and potential energy gains.
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Affiliation(s)
- Wieland Fricke
- School of Biology and Environmental Sciences, University College Dublin (UCD), Belfield, Dublin, 4, Ireland
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20
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Wegner LH. A pump/leak model of growth: the biophysics of cell elongation in higher plants revisited. FUNCTIONAL PLANT BIOLOGY : FPB 2017; 44:185-197. [PMID: 32480556 DOI: 10.1071/fp16184] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/18/2016] [Accepted: 09/08/2016] [Indexed: 06/11/2023]
Abstract
Current concepts of growth hydraulics in higher plants are critically revisited, and it is concluded that they partly fail to interpret the experimental data adequately, particularly in the case of hydroponics-grown roots. Theoretical considerations indicate that the growth rate in roots is controlled by the extensibility of the cell wall, excluding water availability (i.e. hydraulic conductance) as a major constraint. This is supported by the findings that the growth rate does not scale with turgor, and that no radial nor axial water potential gradients have been observed in the root elongation zone. Nevertheless, a water potential deficit ranging from -0.2 to -0.6MPa has repeatedly been reported for growing cells that by far exceeds the shallow trans-membrane water potential difference required for the uptake of growth water. Unexpectedly, growth was also shown to depend on the hydraulic conductance (LP) of the plasma membrane of root cells, even though LP should generally be too large to have an impact on growth. For leaves, similar observations have been reported, but the interpretation of the data is less straightforward. Inconsistencies associated with the current model of growth hydraulics prompt the author to suggest a revised model that comprises, in addition to a passive mechanism of water transport across the plasma membrane of growing cells mediated by aquaporins ('leak') a secondary active water transport ('pump'), in analogy to a mechanism previously demonstrated for mammalian epithelia and postulated for xylem parenchyma cells in roots. Water is hypothesised to be secreted against a trans-membrane water potential difference by cotransport with solutes (salts, sugars, and/or amino acids), taking advantage of the free energy released by this transport step. The solute concentration gradient is supposed to be maintained by a subsequent retrieval of the solutes from the apoplast and back-transport at the expense of metabolic energy. Water secretion tends to reduce the turgor pressure and retards growth, but turgor and, in turn, growth can be upregulated very rapidly independent from any adjustment in the osmolyte deposition rate by increasing LP and/or reducing secondary active water transport, e.g. when the root is exposed to mild osmotic stress, as confirmed by experimental studies.
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Affiliation(s)
- Lars H Wegner
- Karlsruhe Institute of Technology, Institute for Pulsed Power and Microwave Technology (IHM), Campus North, Building 630, Hermann v. Helmholtz Platz 1, 76344 Eggenstein-Leopoldshafen, Germany. Email
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21
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Raven JA. Chloride: essential micronutrient and multifunctional beneficial ion. JOURNAL OF EXPERIMENTAL BOTANY 2017; 38:359-367. [PMID: 28040799 DOI: 10.1093/jxb/erw421] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Cl− is an essential micronutrient for oxygenic photolithotrophs. About half of global primary productivity is carried out by oxygenic photolithotrophs exposed to saline waters with Cl− concentrations orders of magnitude higher than that needed to satisfy the micronutrient requirement. The other half of primary productivity involves terrestrial and freshwater glycophytes sometimes in environments containing significantly more Cl− than is needed for the micronutrient requirement, but less than the toxic Cl– concentration for glycophytes. Intracellular Cl− acts in regulation of cell turgor and volume, including that of stomatal and pulvinar nastic movements, is a major ion in streptophyte and ulvophycean action potentials, and is involved in ion currents flowing around apices of pollen tubes and Acetabularia cells. More work is needed on the essentiality of Cl− in these processes, as well as the recent finding that Cl− at 1–5 mol m−3 increases water use efficiency of growth and leaf area in Nicotiana tabacum.
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Affiliation(s)
- John A Raven
- Division of Plant Science, University of Dundee at the James Hutton Institute, Invergowrie, Dundee, UK
- School of Plant Biology, University of Western Australia MO84, Stirling Highway. Crawley, WA, Australia
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22
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H. Wegner L. Cotransport of water and solutes in plant membranes: The molecular basis, and physiological functions. AIMS BIOPHYSICS 2017. [DOI: 10.3934/biophy.2017.2.192] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
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23
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Drift in ocean currents impacts intergenerational microbial exposure to temperature. Proc Natl Acad Sci U S A 2016; 113:5700-5. [PMID: 27140608 DOI: 10.1073/pnas.1521093113] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Microbes are the foundation of marine ecosystems [Falkowski PG, Fenchel T, Delong EF (2008) Science 320(5879):1034-1039]. Until now, the analytical framework for understanding the implications of ocean warming on microbes has not considered thermal exposure during transport in dynamic seascapes, implying that our current view of change for these critical organisms may be inaccurate. Here we show that upper-ocean microbes experience along-trajectory temperature variability up to 10 °C greater than seasonal fluctuations estimated in a static frame, and that this variability depends strongly on location. These findings demonstrate that drift in ocean currents can increase the thermal exposure of microbes and suggests that microbial populations with broad thermal tolerance will survive transport to distant regions of the ocean and invade new habitats. Our findings also suggest that advection has the capacity to influence microbial community assemblies, such that regions with strong currents and large thermal fluctuations select for communities with greatest plasticity and evolvability, and communities with narrow thermal performance are found where ocean currents are weak or along-trajectory temperature variation is low. Given that fluctuating environments select for individual plasticity in microbial lineages, and that physiological plasticity of ancestors can predict the magnitude of evolutionary responses of subsequent generations to environmental change [Schaum CE, Collins S (2014) Proc Biol Soc 281(1793):20141486], our findings suggest that microbial populations in the sub-Antarctic (∼40°S), North Pacific, and North Atlantic will have the most capacity to adapt to contemporary ocean warming.
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Lavoie M, Raven JA, Levasseur M. Energy cost and putative benefits of cellular mechanisms modulating buoyancy in aflagellate marine phytoplankton. JOURNAL OF PHYCOLOGY 2016; 52:239-251. [PMID: 27037589 DOI: 10.1111/jpy.12390] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/28/2015] [Accepted: 01/15/2016] [Indexed: 06/05/2023]
Abstract
Little information is available on the energetics of buoyancy modulation in aflagellate phytoplankton, which comprises the majority of autotrophic cells found in the ocean. Here, we computed for three aflagellate species of marine phytoplankton (Emiliania huxleyi, Thalassiosira pseudonana, and Ethmodiscus rex) the theoretical minimum energy cost as photons absorbed and nitrogen resource required of the key physiological mechanisms (i.e., replacement of quaternary ammonium by dimethyl-sulfoniopropionate, storage of polysaccharides, and cell wall biosynthesis) affecting the cell's vertical movement as a function of nitrogen (N) availability. These energy costs were also normalized to the capacity of each buoyancy mechanism to modulate sinking or rising rates based on Stokes' law. The three physiological mechanisms could act as ballast in the three species tested in conditions of low N availability at a low fraction (<12%) of the total photon energy cost for growth. Cell wall formation in E. huxleyi was the least costly ballast strategy, whereas in T. pseudonana, the photon energy cost of the three ballast strategies was similar. In E. rex, carbohydrate storage and mobilization appear to be energetically cheaper than modulations in organic solute synthesis to achieve vertical migration. This supports the carbohydrate-ballast strategy for vertical migration for this species, but argues against the theory of replacement of low- or high-density organic solutes. This study brings new insights into the energy cost and potential selective advantages of several strategies modulating the buoyancy of aflagellate marine phytoplankton.
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Affiliation(s)
- Michel Lavoie
- Québec-Océan and Unité Mixte Internationale Takuvik Ulaval-CNRS, Département de Biologie, Université Laval, Québec, Québec, Canada, G1V 0A6
| | - John A Raven
- Division of Plant Science, University of Dundee at the James Hutton Institute, Invergowrie, Dundee, DD2 5DA, UK
- Functional Plant Biology and Climate Change Cluster (C3), University of Technology Sydney, Ultimo, NSW, 2007, Australia
| | - Maurice Levasseur
- Québec-Océan and Unité Mixte Internationale Takuvik Ulaval-CNRS, Département de Biologie, Université Laval, Québec, Québec, Canada, G1V 0A6
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Wegner LH. A thermodynamic analysis of the feasibility of water secretion into xylem vessels against a water potential gradient. FUNCTIONAL PLANT BIOLOGY : FPB 2015; 42:828-835. [PMID: 32480725 DOI: 10.1071/fp15077] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/25/2015] [Accepted: 06/20/2015] [Indexed: 06/11/2023]
Abstract
A series of recent publications has launched a debate on trans-membrane water secretion into root xylem vessels against a water potential gradient, energised by a cotransport with salts (e.g. KCl) that follow their chemical potential gradient. Cation-chloride-cotransporter -type transporters that function in this way in mammalian epithelia were detected in root stelar cells bordering on xylem vessels. Using literature data on barley (Hordeum vulgare L.) seedlings, one study confirmed that K+ and Cl- gradients across stelar cell membranes favour salt efflux. Moreover, the energetic costs of putative water secretion into the xylem (required for maintaining ionic gradients) would amount to just 0.12% of the energy captured by photosynthetic C assimilation if transpirational water flow relied exclusively on this mechanism. Here, a detailed thermodynamic analysis of water secretion into xylem vessels is undertaken, including an approach that exploits its analogy to a desalinisation process. Water backflow due to the passive hydraulic conductivity of stelar cell membranes is also considered. By comparing free energy consumption by putative water secretion with (i) the free energy pool provided by root respiration and (ii) stelar ATPase activity, the feasibility of this mechanism is confirmed but is shown to depend critically on the plant's energy status.
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Affiliation(s)
- Lars H Wegner
- Karlsruhe Institute of Technology, Institute for Pulsed Power and Microwave Technology (IHM), Campus North, Building 630, Hermann v. Helmholtz Platz 1, 76344 Eggenstein-Leopoldshafen, Germany. Email
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26
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Raven JA. Compartmentation of defensive compound synthesis in a red alga. JOURNAL OF PHYCOLOGY 2015; 51:222-224. [PMID: 26986517 DOI: 10.1111/jpy.12287] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Affiliation(s)
- John A Raven
- Division of Plant Science, University of Dundee at the James Hutton Institute, Invergowrie, Dundee, DD2 5DA, UK
- Functional Plant Biology and Climate Change Cluster, University of Technology Sydney, Ultimo, NSW, 2007, Australia
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