1
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Armin G, Kim J, Inomura K. Saturating growth rate against phosphorus concentration explained by macromolecular allocation. mSystems 2023; 8:e0061123. [PMID: 37642424 PMCID: PMC10654069 DOI: 10.1128/msystems.00611-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2023] [Accepted: 06/28/2023] [Indexed: 08/31/2023] Open
Abstract
IMPORTANCE The Monod equation has been used to represent the relationship between growth rate and the environmental nutrient concentration under the limitation of this respective nutrient. This model often serves as a means to connect microorganisms to their environment, specifically in ecosystem and global models. Here, we use a simple model of a marine microorganism cell to illustrate the model's ability to capture the same relationship as Monod, while highlighting the additional physiological details our model provides. In this study, we focus on the relationship between growth rate and phosphorus concentration and find that RNA allocation largely contributes to the commonly observed trend. This work emphasizes the potential role our model could play in connecting microorganisms to the surrounding environment while using realistic physiological representations.
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Affiliation(s)
- Gabrielle Armin
- Graduate School of Oceanography, University of Rhode Island, Narragansett, Rhode Island, USA
| | - Jongsun Kim
- School of Earth, Environmental, and Marine Sciences, University of Texas Rio Grande Valley, Brownsville, Texas, USA
| | - Keisuke Inomura
- Graduate School of Oceanography, University of Rhode Island, Narragansett, Rhode Island, USA
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2
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Yoshizawa S, Azuma T, Kojima K, Inomura K, Hasegawa M, Nishimura Y, Kikuchi M, Armin G, Tsukamoto Y, Miyashita H, Ifuku K, Yamano T, Marchetti A, Fukuzawa H, Sudo Y, Kamikawa R. Light-driven Proton Pumps as a Potential Regulator for Carbon Fixation in Marine Diatoms. Microbes Environ 2023; 38:n/a. [PMID: 37344444 DOI: 10.1264/jsme2.me23015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/23/2023] Open
Abstract
Diatoms are a major phytoplankton group responsible for approximately 20% of carbon fixation on Earth. They perform photosynthesis using light-harvesting chlo-rophylls located in plastids, an organelle obtained through eukaryote-eukaryote endosymbiosis. Microbial rhodopsin, a photoreceptor distinct from chlo-rophyll-based photosystems, was recently identified in some diatoms. However, the physiological function of diatom rhodopsin remains unclear. Heterologous expression techniques were herein used to investigate the protein function and subcellular localization of diatom rhodopsin. We demonstrated that diatom rhodopsin acts as a light-driven proton pump and localizes primarily to the outermost membrane of four membrane-bound complex plastids. Using model simulations, we also examined the effects of pH changes inside the plastid due to rhodopsin-mediated proton transport on photosynthesis. The results obtained suggested the involvement of rhodopsin-mediated local pH changes in a photosynthetic CO2-concentrating mechanism in rhodopsin-possessing diatoms.
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Affiliation(s)
- Susumu Yoshizawa
- Atmosphere and Ocean Research Institute, The University of Tokyo
- Graduate School of Frontier Sciences, The University of Tokyo
- Collaborative Research Institute for Innovative Microbiology, The University of Tokyo
| | - Tomonori Azuma
- Graduate School of Human and Environmental Studies, Kyoto University
| | - Keiichi Kojima
- School of Pharmaceutical Sciences, Okayama University
- Faculty of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University
| | | | - Masumi Hasegawa
- Atmosphere and Ocean Research Institute, The University of Tokyo
- Graduate School of Frontier Sciences, The University of Tokyo
| | - Yosuke Nishimura
- Atmosphere and Ocean Research Institute, The University of Tokyo
| | | | | | - Yuya Tsukamoto
- Atmosphere and Ocean Research Institute, The University of Tokyo
| | - Hideaki Miyashita
- Graduate School of Human and Environmental Studies, Kyoto University
| | | | | | - Adrian Marchetti
- Department of Earth, Marine and Environmental Sciences, University of North Carolina at Chapel Hill
| | | | - Yuki Sudo
- School of Pharmaceutical Sciences, Okayama University
- Faculty of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University
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3
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Masuda T, Inomura K, Gao M, Armin G, Kotabová E, Bernát G, Lawrenz-Kendrick E, Lukeš M, Bečková M, Steinbach G, Komenda J, Prášil O. The balance between photosynthesis and respiration explains the niche differentiation between Crocosphaera and Cyanothece. Comput Struct Biotechnol J 2022; 21:58-65. [PMID: 36514336 PMCID: PMC9732122 DOI: 10.1016/j.csbj.2022.11.029] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2022] [Revised: 11/12/2022] [Accepted: 11/13/2022] [Indexed: 11/18/2022] Open
Abstract
Crocosphaera and Cyanothece are both unicellular, nitrogen-fixing cyanobacteria that prefer different environments. Whereas Crocosphaera mainly lives in nutrient-deplete, open oceans, Cyanothece is more common in coastal, nutrient-rich regions. Despite their physiological similarities, the factors separating their niches remain elusive. Here we performed physiological experiments on clone cultures and expand upon a simple ecological model to show that their different niches can be sufficiently explained by the observed differences in their photosynthetic capacities and rates of carbon (C) consumption. Our experiments revealed that Cyanothece has overall higher photosynthesis and respiration rates than Crocosphaera. A simple growth model of these microorganisms suggests that C storage and consumption are previously under-appreciated factors when evaluating the occupation of niches by different marine nitrogen fixers.
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Affiliation(s)
- Takako Masuda
- Institute of Microbiology, The Czech Academy of Sciences, Opatovický mlýn, 37901 Třeboň, Czech Republic,Corresponding authors.
| | - Keisuke Inomura
- Graduate School of Oceanography, University of Rhode Island, Narragansett, RI 02882, USA
| | - Meng Gao
- Graduate School of Oceanography, University of Rhode Island, Narragansett, RI 02882, USA
| | - Gabrielle Armin
- Graduate School of Oceanography, University of Rhode Island, Narragansett, RI 02882, USA
| | - Eva Kotabová
- Institute of Microbiology, The Czech Academy of Sciences, Opatovický mlýn, 37901 Třeboň, Czech Republic
| | - Gábor Bernát
- Institute of Microbiology, The Czech Academy of Sciences, Opatovický mlýn, 37901 Třeboň, Czech Republic,Balaton Limnological Research Institute, Eötvös Loránd Research Network (ELKH), Tihany, Hungary
| | - Evelyn Lawrenz-Kendrick
- Institute of Microbiology, The Czech Academy of Sciences, Opatovický mlýn, 37901 Třeboň, Czech Republic
| | - Martin Lukeš
- Institute of Microbiology, The Czech Academy of Sciences, Opatovický mlýn, 37901 Třeboň, Czech Republic
| | - Martina Bečková
- Institute of Microbiology, The Czech Academy of Sciences, Opatovický mlýn, 37901 Třeboň, Czech Republic
| | - Gábor Steinbach
- Institute of Microbiology, The Czech Academy of Sciences, Opatovický mlýn, 37901 Třeboň, Czech Republic,Cellular Imaging Laboratory, Biological Research Center, Eötvös Loránd Research Network (ELKH), Szeged, Hungary
| | - Josef Komenda
- Institute of Microbiology, The Czech Academy of Sciences, Opatovický mlýn, 37901 Třeboň, Czech Republic
| | - Ondřej Prášil
- Institute of Microbiology, The Czech Academy of Sciences, Opatovický mlýn, 37901 Třeboň, Czech Republic,Corresponding authors.
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4
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Benavides M, Bonnet S, Le Moigne FAC, Armin G, Inomura K, Hallstrøm S, Riemann L, Berman-Frank I, Poletti E, Garel M, Grosso O, Leblanc K, Guigue C, Tedetti M, Dupouy C. Sinking Trichodesmium fixes nitrogen in the dark ocean. ISME J 2022; 16:2398-2405. [PMID: 35835942 PMCID: PMC9478103 DOI: 10.1038/s41396-022-01289-6] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/31/2022] [Revised: 06/29/2022] [Accepted: 07/05/2022] [Indexed: 01/04/2023]
Abstract
The photosynthetic cyanobacterium Trichodesmium is widely distributed in the surface low latitude ocean where it contributes significantly to N2 fixation and primary productivity. Previous studies found nifH genes and intact Trichodesmium colonies in the sunlight-deprived meso- and bathypelagic layers of the ocean (200-4000 m depth). Yet, the ability of Trichodesmium to fix N2 in the dark ocean has not been explored. We performed 15N2 incubations in sediment traps at 170, 270 and 1000 m at two locations in the South Pacific. Sinking Trichodesmium colonies fixed N2 at similar rates than previously observed in the surface ocean (36-214 fmol N cell-1 d-1). This activity accounted for 40 ± 28% of the bulk N2 fixation rates measured in the traps, indicating that other diazotrophs were also active in the mesopelagic zone. Accordingly, cDNA nifH amplicon sequencing revealed that while Trichodesmium accounted for most of the expressed nifH genes in the traps, other diazotrophs such as Chlorobium and Deltaproteobacteria were also active. Laboratory experiments simulating mesopelagic conditions confirmed that increasing hydrostatic pressure and decreasing temperature reduced but did not completely inhibit N2 fixation in Trichodesmium. Finally, using a cell metabolism model we predict that Trichodesmium uses photosynthesis-derived stored carbon to sustain N2 fixation while sinking into the mesopelagic. We conclude that sinking Trichodesmium provides ammonium, dissolved organic matter and biomass to mesopelagic prokaryotes.
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Affiliation(s)
- Mar Benavides
- Aix Marseille Univ, Université de Toulon, CNRS, IRD, MIO UM 110, 13288, Marseille, France.
- Turing Center for Living Systems, Aix-Marseille University, 13009, Marseille, France.
| | - Sophie Bonnet
- Aix Marseille Univ, Université de Toulon, CNRS, IRD, MIO UM 110, 13288, Marseille, France
| | - Frédéric A C Le Moigne
- Aix Marseille Univ, Université de Toulon, CNRS, IRD, MIO UM 110, 13288, Marseille, France
- LEMAR, Laboratoire des Sciences de l'Environnement Marin, UMR6539, CNRS, UBO, IFREMER, IRD, 29280, Plouzané, Technopôle Brest-Iroise, France
| | - Gabrielle Armin
- Graduate School of Oceanography, University of Rhode Island, South Kingstown, RI, USA
| | - Keisuke Inomura
- Graduate School of Oceanography, University of Rhode Island, South Kingstown, RI, USA
| | - Søren Hallstrøm
- Marine Biological Section, Department of Biology, University of Copenhagen, Helsingør, Denmark
| | - Lasse Riemann
- Marine Biological Section, Department of Biology, University of Copenhagen, Helsingør, Denmark
| | - Ilana Berman-Frank
- Department of Marine Biology, Leon H. Charney School of Marine Sciences, University of Haifa, Mt, Carmel, Haifa, Israel
| | - Emilie Poletti
- Aix Marseille Univ, Université de Toulon, CNRS, IRD, MIO UM 110, 13288, Marseille, France
| | - Marc Garel
- Aix Marseille Univ, Université de Toulon, CNRS, IRD, MIO UM 110, 13288, Marseille, France
| | - Olivier Grosso
- Aix Marseille Univ, Université de Toulon, CNRS, IRD, MIO UM 110, 13288, Marseille, France
| | - Karine Leblanc
- Aix Marseille Univ, Université de Toulon, CNRS, IRD, MIO UM 110, 13288, Marseille, France
| | - Catherine Guigue
- Aix Marseille Univ, Université de Toulon, CNRS, IRD, MIO UM 110, 13288, Marseille, France
| | - Marc Tedetti
- Aix Marseille Univ, Université de Toulon, CNRS, IRD, MIO UM 110, 13288, Marseille, France
| | - Cécile Dupouy
- Aix Marseille Univ, Université de Toulon, CNRS, IRD, MIO UM 110, 13288, Marseille, France
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5
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Kim J, Armin G, Inomura K. Saturating relationship between phytoplankton growth rate and nutrient concentration explained by macromolecular allocation. Curr Res Microb Sci 2022; 3:100167. [PMID: 36518172 PMCID: PMC9742995 DOI: 10.1016/j.crmicr.2022.100167] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2022] [Revised: 08/22/2022] [Accepted: 09/20/2022] [Indexed: 11/16/2022] Open
Abstract
Phytoplankton account for about a half of photosynthesis in the world, making them a key player in the ecological and biogeochemical systems. One of the key traits of phytoplankton is their growth rate because it indicates their productivity and affects their competitive capability. The saturating relationship between phytoplankton growth rate and environmental nutrient concentration has been widely observed yet the mechanisms behind the relationship remain elusive. Here we use a mechanistic model and metadata of phytoplankton to show that the saturating relationship between growth rate and nitrate concentration can be interpreted by intracellular macromolecular allocation. At low nitrate levels, the diffusive nitrate transport linearly increases with the nitrate concentration, while the internal nitrogen requirement increases with the growth rate, leading to a non-linear increase in the growth rate with nitrate. This increased nitrogen requirement is due to the increased allocation to biosynthetic and photosynthetic molecules. The allocation to these molecules reaches a maximum at high nitrate concentration and the growth rate ceases to increase despite high nitrate availability due to carbon limitation. The produced growth rate and nitrate relationships are consistent with the data of phytoplankton across taxa. Our study provides a macromolecular interpretation of the widely observed growth-nutrient relationship and highlights that the key control of the phytoplankton growth exists within the cell.
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Affiliation(s)
- Jongsun Kim
- School of Earth, Environmental, and Marine Sciences, University of Texas Rio Grande Valley, Brownsville, TX, USA
- Graduate School of Oceanography, University of Rhode Island, Narragansett, RI, USA
| | - Gabrielle Armin
- Graduate School of Oceanography, University of Rhode Island, Narragansett, RI, USA
| | - Keisuke Inomura
- Graduate School of Oceanography, University of Rhode Island, Narragansett, RI, USA
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Gao M, Armin G, Inomura K. Low-Ammonium Environment Increases the Nutrient Exchange between Diatom-Diazotroph Association Cells and Facilitates Photosynthesis and N 2 Fixation-a Mechanistic Modeling Analysis. Cells 2022; 11:cells11182911. [PMID: 36139486 PMCID: PMC9497195 DOI: 10.3390/cells11182911] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2022] [Revised: 09/09/2022] [Accepted: 09/13/2022] [Indexed: 11/16/2022] Open
Abstract
Diatom–diazotroph associations (DDAs) are one of the most important symbiotic dinitrogen (N2) fixing groups in the oligotrophic ocean. Despite their capability to fix N2, ammonium (NH4+) remains a key nitrogen (N) source for DDAs, and the effect of NH4+ on their metabolism remains elusive. Here, we developed a coarse-grained, cellular model of the DDA with NH4+ uptake and quantified how the level of extracellular NH4+ influences metabolism and nutrient exchange within the symbiosis. The model shows that, under a fixed growth rate, an increased NH4+ concentration may lower the required level of N2 fixation and photosynthesis, and decrease carbon (C) and N exchange. A low-NH4+ environment leads to more C and N in nutrient exchange and more fixed N2 to support a higher growth rate. With higher growth rates, nutrient exchange and metabolism increased. Our study shows a strong effect of NH4+ on metabolic processes within DDAs, and thus highlights the importance of in situ measurement of NH4+ concentrations.
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Affiliation(s)
- Meng Gao
- Correspondence: ; Tel.: +1-401-771-5757
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7
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Masuda T, Inomura K, Kodama T, Shiozaki T, Kitajima S, Armin G, Matsui T, Suzuki K, Takeda S, Sato M, Prášil O, Furuya K. Crocosphaera as a Major Consumer of Fixed Nitrogen. Microbiol Spectr 2022; 10:e0217721. [PMID: 35770981 PMCID: PMC9431459 DOI: 10.1128/spectrum.02177-21] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2021] [Accepted: 06/05/2022] [Indexed: 11/23/2022] Open
Abstract
Crocosphaera watsonii (hereafter referred to as Crocosphaera) is a key nitrogen (N) fixer in the ocean, but its ability to consume combined-N sources is still unclear. Using in situ microcosm incubations with an ecological model, we show that Crocosphaera has high competitive capability both under low and moderately high combined-N concentrations. In field incubations, Crocosphaera accounted for the highest consumption of ammonium and nitrate, followed by picoeukaryotes. The model analysis shows that cells have a high ammonium uptake rate (~7 mol N [mol N]-1 d-1 at the maximum), which allows them to compete against picoeukaryotes and nondiazotrophic cyanobacteria when combined N is sufficiently available. Even when combined N is depleted, their capability of nitrogen fixation allows higher growth rates compared to potential competitors. These results suggest the high fitness of Crocosphaera in combined-N limiting, oligotrophic oceans heightening its potential significance in its ecosystem and in biogeochemical cycling. IMPORTANCE Crocosphaera watsonii is as a key nitrogen (N) supplier in marine ecosystems, and it has been estimated to contribute up to half of oceanic N2 fixation. Conversely, a recent study reported that Crocosphaera can assimilate combined N and proposed that unicellular diazotrophs can be competitors with non-N2 fixing phytoplankton for combined N. Despite its importance in nitrogen cycling, the methods by which Crocosphaera compete are not currently fully understood. Here, we present a new role of Crocosphaera as a combined-N consumer: a competitor against nondiazotrophic phytoplankton for combined N. In this study, we combined in situ microcosm experiments and an ecosystem model to quantitatively evaluate the combined-N consumption by Crocosphaera and other non-N2 fixing phytoplankton. Our results suggest the high fitness of Crocosphaera in combined-N limiting, oligotrophic oceans and, thus, heightens its potential significance in its ecosystem and in biogeochemical cycling.
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Affiliation(s)
- Takako Masuda
- Department of Aquatic Bioscience, The University of Tokyo, Tokyo, Japan
- Institute of Microbiology, The Czech Academy of Sciences, Třeboň, Czech Republic
| | - Keisuke Inomura
- Graduate School of Oceanography, University of Rhode Island, Narragansett, Rhode Island, USA
| | - Taketoshi Kodama
- Department of Aquatic Bioscience, The University of Tokyo, Tokyo, Japan
| | - Takuhei Shiozaki
- Department of Aquatic Bioscience, The University of Tokyo, Tokyo, Japan
| | - Satoshi Kitajima
- Department of Aquatic Bioscience, The University of Tokyo, Tokyo, Japan
| | - Gabrielle Armin
- Graduate School of Oceanography, University of Rhode Island, Narragansett, Rhode Island, USA
| | - Takato Matsui
- Graduate School of Environmental Science/Faculty of Environmental Earth Science, Hokkaido University, Sapporo, Japan
| | - Koji Suzuki
- Graduate School of Environmental Science/Faculty of Environmental Earth Science, Hokkaido University, Sapporo, Japan
| | - Shigenobu Takeda
- Department of Aquatic Bioscience, The University of Tokyo, Tokyo, Japan
| | - Mitsuhide Sato
- Department of Aquatic Bioscience, The University of Tokyo, Tokyo, Japan
| | - Ondřej Prášil
- Institute of Microbiology, The Czech Academy of Sciences, Třeboň, Czech Republic
| | - Ken Furuya
- Department of Aquatic Bioscience, The University of Tokyo, Tokyo, Japan
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Inomura K, Masuda T, Eichner M, Rabouille S, Zavřel T, Červený J, Vancová M, Bernát G, Armin G, Claquin P, Kotabová E, Stephan S, Suggett DJ, Deutsch C, Prášil O. Quantifying Cyanothece growth under DIC limitation. Comput Struct Biotechnol J 2021; 19:6456-6464. [PMID: 34938417 PMCID: PMC8665340 DOI: 10.1016/j.csbj.2021.11.036] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2021] [Revised: 11/22/2021] [Accepted: 11/22/2021] [Indexed: 11/26/2022] Open
Abstract
The photoautotrophic, unicellular N2-fixer, Cyanothece, is a model organism that has been widely used to study photosynthesis regulation, the structure of photosystems, and the temporal segregation of carbon (C) and nitrogen (N) fixation in light and dark phases of the diel cycle. Here, we present a simple quantitative model and experimental data that together, suggest external dissolved inorganic carbon (DIC) concentration as a major limiting factor for Cyanothece growth, due to its high C-storage requirement. Using experimental data from a parallel laboratory study as a basis, we show that after the onset of the light period, DIC was rapidly consumed by photosynthesis, leading to a sharp drop in the rate of photosynthesis and C accumulation. In N2-fixing cultures, high rates of photosynthesis in the morning enabled rapid conversion of DIC to intracellular C storage, hastening DIC consumption to levels that limited further uptake. The N2-fixing condition allows only a small fraction of fixed C for cellular growth since a large fraction was reserved in storage to fuel night-time N2 fixation. Our model provides a framework for resolving DIC limitation in aquatic ecosystem simulations, where DIC as a growth-limiting factor has rarely been considered, and importantly emphasizes the effect of intracellular C allocation on growth rate that varies depending on the growth environment.
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Affiliation(s)
- Keisuke Inomura
- Graduate School of Oceanography, University of Rhode Island, Narragansett, Rhode Island, USA
| | - Takako Masuda
- Institute of Microbiology, The Czech Academy of Sciences, Třeboň, Czech Republic
| | - Meri Eichner
- Institute of Microbiology, The Czech Academy of Sciences, Třeboň, Czech Republic
| | - Sophie Rabouille
- Sorbonne Université, CNRS, Laboratoire d'Océanographie Microbienne, LOMIC, F-66650 Banyuls-sur-mer, France
| | - Tomáš Zavřel
- Department of Adaptive Biotechnologies, Global Change Research Institute, Czech Academy of Sciences, Brno, Czech Republic
| | - Jan Červený
- Department of Adaptive Biotechnologies, Global Change Research Institute, Czech Academy of Sciences, Brno, Czech Republic
| | - Marie Vancová
- Laboratory of Electron Microscopy, Institute of Parasitology, Biology Centre of the Czech Academy of Sciences and Faculty of Science, University of South Bohemia, České Budějovice, Czech Republic
| | - Gábor Bernát
- Institute of Microbiology, The Czech Academy of Sciences, Třeboň, Czech Republic.,Balaton Limnological Research Institute, Eötvös Loránd Research Network (ELKH), Tihany, Hungary
| | - Gabrielle Armin
- Graduate School of Oceanography, University of Rhode Island, Narragansett, Rhode Island, USA
| | - Pascal Claquin
- Laboratoire de Biologie des ORganismes et Ecosystèmes Aquatiques (BOREA), UMR 8067, Muséum National d'Histoire Naturelle, CNRS, IRD Sorbonne Université, Université de Caen Normandie, Normandie Université, Esplanade de la Paix, F-14032 Caen, France
| | - Eva Kotabová
- Institute of Microbiology, The Czech Academy of Sciences, Třeboň, Czech Republic
| | - Susanne Stephan
- Department Experimental Limnology, Leibniz Institute of Freshwater Ecology and Inland Fisheries, Stechlin, Germany
| | - David J Suggett
- University of Technology Sydney, Climate Change Cluster, Faculty of Science, Ultimo, NSW 2007, Australia
| | - Curtis Deutsch
- School of Oceanography, University of Washington, Seattle, WA, USA
| | - Ondřej Prášil
- Institute of Microbiology, The Czech Academy of Sciences, Třeboň, Czech Republic
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9
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Armin G, Inomura K. Modeled temperature dependencies of macromolecular allocation and elemental stoichiometry in phytoplankton. Comput Struct Biotechnol J 2021; 19:5421-5427. [PMID: 34712391 PMCID: PMC8515405 DOI: 10.1016/j.csbj.2021.09.028] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2021] [Revised: 09/20/2021] [Accepted: 09/26/2021] [Indexed: 11/23/2022] Open
Abstract
Warming oceans may affect how phytoplankton allocate nutrients to essential cellular processes. Despite the potential impact of such processes on future biogeochemical cycles, questions remain about how temperature affects macromolecular allocation and elemental stoichiometry within phytoplankton cells. Here, we present a macromolecular model of phytoplankton and the effect of increasing temperature on the intracellular allocation of nutrients at a constant growth rate. When temperature increases under nitrogen (N) and phosphorus (P) co-limitation, the model shows less investment in phosphorus-rich RNA molecules relative to nitrogen-rich proteins, leading to a more severe decrease in cellular P:C than N:C causing increased cellular N:P values. Under P limitation, the model shows a similar pattern, but when excess P is available under N limitation, we predict lowered N:P due to the effect of luxury uptake of P. We reflected our model result on the surface ocean showing similar latitudinal patterns in N:P and P:C to observation and other model predictions, suggesting a considerable impact of temperature on constraining the elemental stoichiometry in the ocean.
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Affiliation(s)
- Gabrielle Armin
- Graduate School of Oceanography, University of Rhode Island, Narragansett, RI, United States
| | - Keisuke Inomura
- Graduate School of Oceanography, University of Rhode Island, Narragansett, RI, United States
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Axenovich SA, Kazarov AR, Boiko AD, Armin G, Roninson IB, Gudkov AV. Altered expression of ubiquitous kinesin heavy chain results in resistance to etoposide and hypersensitivity to colchicine: mapping of the domain associated with drug response. Cancer Res 1998; 58:3423-8. [PMID: 9699675] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
The motor protein kinesin is a tetramer consisting of two heavy and two light chains. Expression of an antisense RNA fragment derived from the mouse ubiquitous kinesin heavy chain (uKHC) cDNA is associated with a unique type of multidrug resistance. We analyzed the effects of retroviral transduction of the human uKHC and its derivatives on drug sensitivity of the human fibrosarcoma cell line HT1080. Surprisingly, overexpression of full-length uKHC and its variants that were deficient in the NH2-terminal motor domain produced a phenotype similar to that of antisense RNA, characterized by resistance to etoposide and collateral sensitivity to colchicine. This altered drug response, therefore, appears to be a general consequence of kinesin deregulation. The genetic suppressor element approach was applied to map the determinants of drug response in the kinesin heavy chain. A sense-oriented genetic suppressor element conferring resistance to etoposide was isolated from a retroviral library of randomly fragmented uKHC cDNA. This element encodes the last 55 amino acids of uKHC, suggesting that the COOH-terminal tail domain of uKHC is involved in the cellular drug response.
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Affiliation(s)
- S A Axenovich
- Department of Molecular Genetics, University of Illinois at Chicago, 60607, USA
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Komarova EA, Chernov MV, Franks R, Wang K, Armin G, Zelnick CR, Chin DM, Bacus SS, Stark GR, Gudkov AV. Transgenic mice with p53-responsive lacZ: p53 activity varies dramatically during normal development and determines radiation and drug sensitivity in vivo. EMBO J 1997; 16:1391-400. [PMID: 9135154 PMCID: PMC1169736 DOI: 10.1093/emboj/16.6.1391] [Citation(s) in RCA: 225] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
To analyze the involvement of p53-dependent transcriptional activation in normal development and in response to DNA damage in vivo, we created transgenic mice with a lacZ reporter gene under the control of a p53-responsive promoter. Five independent strains showed similar patterns of transgene expression. In untreated animals, lacZ expression was limited to the developing nervous system of embryos and newborn mice and was strongly decreased in the adult brain. gamma-irradiation or adriamycin treatment induced lacZ expression in the majority of cells of early embryos and in the spleen, thymus and small intestine in adult mice. Transgene expression was p53 dependent and coincided with the sites of strong p53 accumulation. The lacZ-expressing tissues and early embryos, unlike other adult tissues and late embryos, are characterized by high levels of p53 mRNA expression and respond to DNA damage by massive apoptotic cell death. Analysis of p53-null mice showed that this apoptosis is p53 dependent. These data suggest that p53 activity, monitored by the reporter lacZ transgene, is the determinant of radiation and drug sensitivity in vivo and indicate the importance of tissue and stage specificity of p53 regulation at the level of mRNA expression.
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Affiliation(s)
- E A Komarova
- Department of Genetics, University of Illinois at Chicago, 60607, USA
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