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Via CW, Grauso L, McManus KM, Kirk RD, Kim AM, Webb EA, Held NA, Saito MA, Scarpato S, Zimba PV, Moeller PDR, Mangoni A, Bertin MJ. Spatial and Temporal Resolution of Cyanobacterial Bloom Chemistry Reveals an Open-Ocean Trichodesmium thiebautii as a Talented Producer of Specialized Metabolites. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2024. [PMID: 38758591 DOI: 10.1021/acs.est.3c10739] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2024]
Abstract
While the ecological role that Trichodesmium sp. play in nitrogen fixation has been widely studied, little information is available on potential specialized metabolites that are associated with blooms and standing stock Trichodesmium colonies. While a collection of biological material from a T. thiebautii bloom event from North Padre Island, Texas, in 2014 indicated that this species was a prolific producer of chlorinated specialized metabolites, additional spatial and temporal resolution was needed. We have completed these metabolite comparison studies, detailed in the current report, utilizing LC-MS/MS-based molecular networking to visualize and annotate the specialized metabolite composition of these Trichodesmium blooms and colonies in the Gulf of Mexico (GoM) and other waters. Our results showed that T. thiebautii blooms and colonies found in the GoM have a remarkably consistent specialized metabolome. Additionally, we isolated and characterized one new macrocyclic compound from T. thiebautii, trichothilone A (1), which was also detected in three independent cultures of T. erythraeum. Genome mining identified genes predicted to synthesize certain functional groups in the T. thiebautii metabolites. These results provoke intriguing questions of how these specialized metabolites affect Trichodesmium ecophysiology, symbioses with marine invertebrates, and niche development in the global oligotrophic ocean.
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Affiliation(s)
- Christopher W Via
- Department of Biomedical and Pharmaceutical Sciences, College of Pharmacy, University of Rhode Island, 7 Greenhouse Road, Kingston, Rhode Island 02881, United States
| | - Laura Grauso
- Dipartimento di Agraria, Università degli Studi di Napoli Federico II, via Universita 100, Portici Napoli 80055, Italy
| | - Kelly M McManus
- Department of Biomedical and Pharmaceutical Sciences, College of Pharmacy, University of Rhode Island, 7 Greenhouse Road, Kingston, Rhode Island 02881, United States
| | - Riley D Kirk
- Department of Biomedical and Pharmaceutical Sciences, College of Pharmacy, University of Rhode Island, 7 Greenhouse Road, Kingston, Rhode Island 02881, United States
| | - Andrew M Kim
- Department of Biomedical and Pharmaceutical Sciences, College of Pharmacy, University of Rhode Island, 7 Greenhouse Road, Kingston, Rhode Island 02881, United States
| | - Eric A Webb
- Marine and Environmental Biology, Department of Biological Sciences, University of Southern California, Los Angeles, California 90089, United States
| | - Noelle A Held
- Marine and Environmental Biology, Department of Biological Sciences, University of Southern California, Los Angeles, California 90089, United States
| | - Mak A Saito
- Department of Marine Chemistry and Geochemistry, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts 02543, United States
| | - Silvia Scarpato
- Dipartimento di Farmacia, Università degli Studi di Napoli Federico II, via Domenico Montesano 49, Napoli 80131, Italy
| | - Paul V Zimba
- Rice Rivers Center, Virginia Commonwealth University, Richmond, Virginia 23284, United States
| | - Peter D R Moeller
- Harmful Algal Bloom Monitoring and Reference Branch, Stressor Detection and Impacts Division, National Ocean Service/NOAA, Hollings Marine Laboratory, 331 Fort Johnson Road, Charleston, South Carolina 29412, United States
| | - Alfonso Mangoni
- Dipartimento di Farmacia, Università degli Studi di Napoli Federico II, via Domenico Montesano 49, Napoli 80131, Italy
| | - Matthew J Bertin
- Department of Chemistry, Case Western Reserve University, Cleveland, Ohio 44106, United States
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Reich HG, Camp EF, Roger LM, Putnam HM. The trace metal economy of the coral holobiont: supplies, demands and exchanges. Biol Rev Camb Philos Soc 2023; 98:623-642. [PMID: 36897260 DOI: 10.1111/brv.12922] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2022] [Revised: 11/07/2022] [Accepted: 11/08/2022] [Indexed: 11/23/2022]
Abstract
The juxtaposition of highly productive coral reef ecosystems in oligotrophic waters has spurred substantial interest and progress in our understanding of macronutrient uptake, exchange, and recycling among coral holobiont partners (host coral, dinoflagellate endosymbiont, endolithic algae, fungi, viruses, bacterial communities). By contrast, the contribution of trace metals to the physiological performance of the coral holobiont and, in turn, the functional ecology of reef-building corals remains unclear. The coral holobiont's trace metal economy is a network of supply, demand, and exchanges upheld by cross-kingdom symbiotic partnerships. Each partner has unique trace metal requirements that are central to their biochemical functions and the metabolic stability of the holobiont. Organismal homeostasis and the exchanges among partners determine the ability of the coral holobiont to adjust to fluctuating trace metal supplies in heterogeneous reef environments. This review details the requirements for trace metals in core biological processes and describes how metal exchanges among holobiont partners are key to sustaining complex nutritional symbioses in oligotrophic environments. Specifically, we discuss how trace metals contribute to partner compatibility, ability to cope with stress, and thereby to organismal fitness and distribution. Beyond holobiont trace metal cycling, we outline how the dynamic nature of the availability of environmental trace metal supplies can be influenced by a variability of abiotic factors (e.g. temperature, light, pH, etc.). Climate change will have profound consequences on the availability of trace metals and further intensify the myriad stressors that influence coral survival. Lastly, we suggest future research directions necessary for understanding the impacts of trace metals on the coral holobiont symbioses spanning subcellular to organismal levels, which will inform nutrient cycling in coral ecosystems more broadly. Collectively, this cross-scale elucidation of the role of trace metals for the coral holobiont will allow us to improve forecasts of future coral reef function.
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Affiliation(s)
- Hannah G Reich
- Department of Biological Sciences, University of Rhode Island, 120 Flagg Road, Kingston, RI, 02881, USA
| | - Emma F Camp
- Climate Change Cluster, University of Technology Sydney, Ultimo, NSW, Australia
| | - Liza M Roger
- Chemical & Life Science Engineering, Virginia Commonwealth University, 601 W. Main Street, Richmond, VA, 23284, USA
| | - Hollie M Putnam
- Department of Biological Sciences, University of Rhode Island, 120 Flagg Road, Kingston, RI, 02881, USA
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3
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Hou X, Hu X. Self-Assembled Nanoscale Manganese Oxides Enhance Carbon Capture by Diatoms. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2022; 56:17215-17226. [PMID: 36375171 DOI: 10.1021/acs.est.2c04500] [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: 06/16/2023]
Abstract
Continuous CO2 emissions from human activities increase atmospheric CO2 concentrations and affect global climate change. The carbon storage capacity of the ocean is 20-fold higher than that of the land, and diatoms contribute to approximately 40% of carbon capture in the ocean. Manganese (Mn) is a major driver of marine phytoplankton growth and the marine carbon pump. Here, we discovered self-assembled manganese oxides (MnOx) for CO2 fixation in a diatom-based biohybrid system. MnOx shared key features (e.g., di-μ-oxo-bridged Mn-Mn) with the Mn4CaO5 cluster of the biological catalyst in photosystem II and promoted photosynthesis and carbon capture by diatoms/MnOx. The CO2 capture capacity of diatoms/MnOx was 1.5-fold higher than that of diatoms alone. Diatoms/MnOx easily allocated carbon into proteins and lipids instead of carbohydrates. Metabolomics showed that the contents of several metabolites (e.g., lysine and inositol) were positively associated with increased CO2 capture. Diatoms/MnOx upregulated six genes encoding photosynthesis core proteins and a key rate-limiting enzyme (Rubisco, ribulose 1,5-bisphosphate carboxylase-oxygenase) in the Calvin-Benson-Bassham carbon assimilation cycle, revealing the link between MnOx and photosynthesis. These findings provide a route for offsetting anthropogenic CO2 emissions and inspiration for self-assembled biohybrid systems for carbon capture by marine phytoplankton.
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Affiliation(s)
- Xuan Hou
- Key Laboratory of Pollution Processes and Environmental Criteria (Ministry of Education)/Tianjin Key Laboratory of Environmental Remediation and Pollution Control, College of Environmental Science and Engineering, Nankai University, Tianjin300350, China
| | - Xiangang Hu
- Key Laboratory of Pollution Processes and Environmental Criteria (Ministry of Education)/Tianjin Key Laboratory of Environmental Remediation and Pollution Control, College of Environmental Science and Engineering, Nankai University, Tianjin300350, China
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Electrostatic effects on ligand-assisted transfer of metals to (bio)accumulating interfaces and metal complexes (bioavai)lability. Colloids Surf A Physicochem Eng Asp 2022. [DOI: 10.1016/j.colsurfa.2022.130679] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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5
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Luo J, Huang Z, Li S, Zheng F, Liu F, Huang Q, Huang X, Xie H. Photodegradation Kinetics and Deep Learning-Based Intelligent Colorimetric Method for Bioavailability-Based Dissolved Iron Speciation. Anal Chem 2022; 94:14801-14809. [PMID: 36239120 DOI: 10.1021/acs.analchem.2c04014] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Via the photodegradation of dissolved iron (dFe) complexes in the euphotic zone, released free Fe(III) is the most important source of bioavailable iron for eukaryotic phytoplankton. There is an urgent need to establish bioavailability-based dissolved iron speciation (BDIS) methods. Herein, an intelligent system with dFe pretreatment and a colorimetric sensor is developed for real-time monitoring of newly generated Fe(III) ions. According to the photodegradation kinetics of dFe, including kinetic constant and photogenerated time of free Fe(III) ions, 3 sources, 6 kinds, and 12 species of dFe are determined by our photocatalytic-assisted colorimetric sensor and deep learning model within 20.0 min. The algal dFe-uptake for 4 days can be predicted by BDIS with correlation coefficient 0.85, which could be explained by the hard and soft acids and bases theory (HSAB) and density functional theory (DFT). These results successfully demonstrate the proof-of-concept for photodegradation kinetics-based speciation and bioavailability assessments of dissolved metals.
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Affiliation(s)
- Jiayi Luo
- College of Chemistry, Chemical Engineering & Environmental Science, Minnan Normal University, Zhangzhou 363000, China
| | - Zhaojing Huang
- College of Chemistry, Chemical Engineering & Environmental Science, Minnan Normal University, Zhangzhou 363000, China
| | - Shunxing Li
- College of Chemistry, Chemical Engineering & Environmental Science, Minnan Normal University, Zhangzhou 363000, China.,Fujian Province Key Laboratory of Modern Analytical Science and Separation Technology, Fujian Province University Key Laboratory of Pollution Monitoring and Control, Minnan Normal University, Zhangzhou 3630003, China
| | - Fengying Zheng
- College of Chemistry, Chemical Engineering & Environmental Science, Minnan Normal University, Zhangzhou 363000, China.,Fujian Province Key Laboratory of Modern Analytical Science and Separation Technology, Fujian Province University Key Laboratory of Pollution Monitoring and Control, Minnan Normal University, Zhangzhou 3630003, China
| | - Fengjiao Liu
- College of Chemistry, Chemical Engineering & Environmental Science, Minnan Normal University, Zhangzhou 363000, China.,Fujian Province Key Laboratory of Modern Analytical Science and Separation Technology, Fujian Province University Key Laboratory of Pollution Monitoring and Control, Minnan Normal University, Zhangzhou 3630003, China
| | - Qianyan Huang
- College of Chemistry, Chemical Engineering & Environmental Science, Minnan Normal University, Zhangzhou 363000, China
| | - Xuguang Huang
- College of Chemistry, Chemical Engineering & Environmental Science, Minnan Normal University, Zhangzhou 363000, China.,Fujian Province Key Laboratory of Modern Analytical Science and Separation Technology, Fujian Province University Key Laboratory of Pollution Monitoring and Control, Minnan Normal University, Zhangzhou 3630003, China
| | - Haijiao Xie
- Hangzhou Yanqu Information Technology Company of Limited Liability, Hangzhou 310003, China
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Liu F, Gledhill M, Tan QG, Zhu K, Zhang Q, Salaün P, Tagliabue A, Zhang Y, Weiss D, Achterberg EP, Korchev Y. Phycosphere pH of unicellular nano- and micro- phytoplankton cells and consequences for iron speciation. THE ISME JOURNAL 2022; 16:2329-2336. [PMID: 35798938 PMCID: PMC9478132 DOI: 10.1038/s41396-022-01280-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/02/2021] [Revised: 06/15/2022] [Accepted: 06/22/2022] [Indexed: 11/15/2022]
Abstract
Surface ocean pH is declining due to anthropogenic atmospheric CO2 uptake with a global decline of ~0.3 possible by 2100. Extracellular pH influences a range of biological processes, including nutrient uptake, calcification and silicification. However, there are poor constraints on how pH levels in the extracellular microenvironment surrounding phytoplankton cells (the phycosphere) differ from bulk seawater. This adds uncertainty to biological impacts of environmental change. Furthermore, previous modelling work suggests that phycosphere pH of small cells is close to bulk seawater, and this has not been experimentally verified. Here we observe under 140 μmol photons·m−2·s−1 the phycosphere pH of Chlamydomonas concordia (5 µm diameter), Emiliania huxleyi (5 µm), Coscinodiscus radiatus (50 µm) and C. wailesii (100 µm) are 0.11 ± 0.07, 0.20 ± 0.09, 0.41 ± 0.04 and 0.15 ± 0.20 (mean ± SD) higher than bulk seawater (pH 8.00), respectively. Thickness of the pH boundary layer of C. wailesii increases from 18 ± 4 to 122 ± 17 µm when bulk seawater pH decreases from 8.00 to 7.78. Phycosphere pH is regulated by photosynthesis and extracellular enzymatic transformation of bicarbonate, as well as being influenced by light intensity and seawater pH and buffering capacity. The pH change alters Fe speciation in the phycosphere, and hence Fe availability to phytoplankton is likely better predicted by the phycosphere, rather than bulk seawater. Overall, the precise quantification of chemical conditions in the phycosphere is crucial for assessing the sensitivity of marine phytoplankton to ongoing ocean acidification and Fe limitation in surface oceans.
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Liu W, Worms IAM, Jakšić Ž, Slaveykova VI. Aquatic organisms modulate the bioreactivity of engineered nanoparticles: focus on biomolecular corona. FRONTIERS IN TOXICOLOGY 2022; 4:933186. [PMID: 36060121 PMCID: PMC9437328 DOI: 10.3389/ftox.2022.933186] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2022] [Accepted: 07/11/2022] [Indexed: 11/15/2022] Open
Abstract
The increased use of nanoparticle (NP)-enabled materials in everyday-life products have raised concerns about their environmental implications and safety. This motivated the extensive research in nanoecotoxicology showing the possibility that NPs could cause harm to the aquatic organisms if present at high concentrations. By contrast, studies dealing with influence that organisms could exert on the fate and thus effects of NPs are still very rare. Drawing on the existing up-to-date knowledge we critically discuss the formation of biomolecular corona as one of the mechanisms by which organisms exerted control on the NPs fate in the aquatic and biotic environments. We focused the formation of corona by exogeneous and endogenous biomolecules and illustrated the discussion with the specific example of phytoplankton and aquatic invertebrate species. We highlighted the necessity to incorporate the concept of biomolecular corona within more general framework considering the feedback of aquatic organisms and the control they exert in shaping the fate and impact of NPs in the aquatic and biological environment. In our view such broader perspective will contribute to get novel insights into the drivers of environmental transformations of NPs and their mechanisms, which are important in environmental risk assessment.
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Affiliation(s)
- Wei Liu
- Department F.-A. Forel for Environmental and Aquatic Sciences, Environmental Biogeochemistry and Ecotoxicology, Faculty of Sciences, Earth and Environment Sciences, University of Geneva, Uni Carl Vogt, Geneva, Switzerland
| | - Isabelle A. M. Worms
- Department F.-A. Forel for Environmental and Aquatic Sciences, Environmental Biogeochemistry and Ecotoxicology, Faculty of Sciences, Earth and Environment Sciences, University of Geneva, Uni Carl Vogt, Geneva, Switzerland
| | - Željko Jakšić
- Center for Marine Research Rovinj, Institute Ruđer Bošković, Rovinj, Croatia
| | - Vera I. Slaveykova
- Department F.-A. Forel for Environmental and Aquatic Sciences, Environmental Biogeochemistry and Ecotoxicology, Faculty of Sciences, Earth and Environment Sciences, University of Geneva, Uni Carl Vogt, Geneva, Switzerland
- *Correspondence: Vera I. Slaveykova,
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Exploiting Catabolite Repression and Stringent Response to Control Delay and Multimodality of Bioluminescence Signal by Metal Whole-Cell Biosensors: Interplay between Metal Bioavailability and Nutritional Medium Conditions. BIOSENSORS 2022; 12:bios12050327. [PMID: 35624628 PMCID: PMC9139025 DOI: 10.3390/bios12050327] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/23/2022] [Revised: 05/09/2022] [Accepted: 05/10/2022] [Indexed: 12/02/2022]
Abstract
The time-dependent response of metal-detecting whole-cell luminescent bacterial sensors is impacted by metal speciation/bioavailability in solution. The comprehensive understanding of such connections requires the consideration of the bacterial energy metabolism at stake and the effects of supplied food on cells’ capability to convert bioaccumulated metals into light. Accordingly, we investigated the time response (48 h assay) of PzntA-luxCDABE Escherichia coli Cd biosensors in media differing with respect to sources of amino acids (tryptone or Lysogeny Broth) and carbon (glucose, xylose and mixtures thereof). We show that the resulting coupling between the stringent cell response and glucose/xylose-mediated catabolite repressions lead to well-defined multimodalities and shapes of the bioluminescence signal over time. Based on a recent theory for the time–response of metal-sensing luminescent bacteria, successful theoretical reconstructions of the bioluminescence signals are reported under all Cd concentrations (0–20 nM) and nutritive conditions examined. This analysis leads to the evaluation of time-dependent cell photoactivity and qualitative information on metal speciation/bioavailability in solution. Biosensor performance and the position, shape, number, and magnitude of detected peaks are discussed in relation to the metabolic pathways operative during the successive light emission modes identified here over time. Altogether, the results clarify the contributions of metal/nutrient bio-availabilities and food quality to cell response typology.
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Synergistic use of siderophores and weak organic ligands during zinc transport in the rhizosphere controlled by pH and ion strength gradients. Sci Rep 2022; 12:6774. [PMID: 35474082 PMCID: PMC9042811 DOI: 10.1038/s41598-022-10493-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2021] [Accepted: 04/04/2022] [Indexed: 11/09/2022] Open
Abstract
Citrate (Cit) and Deferoxamine B (DFOB) are two important organic ligands coexisting in soils with distinct different affinities for metal ions. It has been theorized that siderophores and weak organic ligands play a synergistic role during the transport of micronutrients in the rhizosphere, but the geochemical controls of this process remain unknown. Here we test the hypothesis that gradients in pH and ion strength regulate and enable the cooperation. To this end, first we use potentiometric titrations to identify the dominant Zn(II)–Cit and Zn(II)–DFOB complexes and to determine their ionic strength dependent stability constants between 0 and 1 mol dm−3. We parametrise the Extended Debye-Hückel (EDH) equation and determine accurate intrinsic association constants (logβ0) for the formation of the complexes present. The speciation model developed confirms the presence of [Zn(Cit)]−, [Zn(HCit)], [Zn2(Cit)2(OH)2]4−, and [Zn(Cit)2]4−, with [Zn(Cit)]− and [Zn2(Cit)2(OH)2]4− the dominant species in the pH range relevant to rhizosphere. We propose the existence of a new [Zn(Cit)(OH)3]4− complex above pH 10. We also verify the existence of two hexadentate Zn(II)–DFOB species, i.e., [Zn(DFOB)]− and [Zn(HDFOB)], and of one tetradentate species [Zn(H2DFOB)]+. Second, we identify the pH and ionic strength dependent ligand exchange points (LEP) of Zn with citrate and DFOB and the stability windows for Zn(II)–Cit and Zn(II)–DFOB complexes in NaCl and rice soil solutions. We find that the LEPs fall within the pH and ionic strength gradients expected in rhizospheres and that the stability windows for Zn(II)–citrate and Zn(II)–DFOB, i.e., low and high affinity ligands, can be distinctly set off. This suggests that pH and ion strength gradients allow for Zn(II) complexes with citrate and DFOB to dominate in different parts of the rhizosphere and this explains why mixtures of low and high affinity ligands increase leaching of micronutrients in soils. Speciation models of soil solutions using newly determined association constants demonstrate that the presence of dissolved organic matter and inorganic ligands (i.e., bicarbonate, phosphate, sulphate, or chlorides) do neither affect the position of the LEP nor the width of the stability windows significantly. In conclusion, we demonstrate that cooperative and synergistic ligand interaction between low and high affinity ligands is a valid mechanism for controlling zinc transport in the rhizosphere and possibly in other environmental reservoirs such as in the phycosphere. Multiple production of weak and strong ligands is therefore a valid strategy of plants and other soil organisms to improve access to micronutrients.
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Koppel DJ, Whitelaw N, Adams MS, King CK, Jolley DF. The microalga Phaeocystis antarctica is tolerant to salinity and metal mixture toxicity interactions. ENVIRONMENTAL SCIENCE. PROCESSES & IMPACTS 2021; 23:1362-1375. [PMID: 34351327 DOI: 10.1039/d1em00233c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Salinity in the Antarctic nearshore marine environment is seasonally dynamic and climate change is driving greater variability through altered sea ice seasons, ocean evaporation rates, and increased terrestrial ice melt. The greatest salinity changes are likely to occur in the nearshore environment where elevated metal exposures from historical waste or wastewater discharge occur. How salinity changes affect metal toxicity has not yet been investigated. This study investigated the toxicity of cadmium, copper, nickel, lead, and zinc, and their equitoxic mixtures across a salinity gradient to the Antarctic marine microalga Phaeocystis antarctica. In the metal-free control exposures, algal population growth rates were significantly lower at salinities <20 PSU or >35 PSU compared to the control growth rate at 35 PSU of 0.60 ± 0.05 doublings per day and there was no growth below 10 or above 68 PSU. Salinity-induced changes to metal speciation and activity were investigated using the WHAM VII model. Percentages of free ion activity and metal-organic complexes increased at decreasing salinities while the activity of inorganic metal complexes increased with increasing salinities. Despite metal speciation and activity changes, toxicity was generally unchanged across the salinity gradient except that there was less copper toxicity and more lead toxicity than model predictions at salinities of 15 and 25 PSU and antagonistic interactions in metal-mixture treatments. In mixtures with and without copper, it was shown that copper was responsible for ∼50% of the antagonism from observed toxicity at salinities below 45 PSU. Across all treatments, using different metal fractions in toxicity models did not improve toxicity predictions compared to dissolved metal concentrations. These results provide evidence that P. antarctica is unlikely to be at a greater risk from metal contaminants as a result of salinity changes.
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Affiliation(s)
- Darren J Koppel
- Faculty of Science and Engineering, Curtin University, Perth, WA, Australia.
- Faculty of Science, Medicine, and Health, University of Wollongong, Wollongong, NSW, Australia
- CSIRO Land and Water, Lucas Heights, NSW, Australia
| | - Nicholas Whitelaw
- Faculty of Science, Medicine, and Health, University of Wollongong, Wollongong, NSW, Australia
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Northover GHR, Garcia-España E, Weiss DJ. Unravelling the modus operandi of phytosiderophores during zinc uptake in rice: the importance of geochemical gradients and accurate stability constants. JOURNAL OF EXPERIMENTAL BOTANY 2021; 72:1517-1526. [PMID: 33332561 DOI: 10.1093/jxb/eraa580] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/03/2020] [Accepted: 12/10/2020] [Indexed: 06/12/2023]
Abstract
Micronutrient deficiencies threaten global food production. Attempts to biofortify crops rely on a clear understanding of micronutrient uptake processes. Zinc deficiency in rice is a serious problem. One of the pathways proposed for the transfer of zinc from soils into rice plants involves deoxymugineic acid (DMA), a phytosiderophore. The idea that phytosiderophores play a wider role in nutrition of Poaceae beyond iron is well established. However, key mechanistic details of the DMA-assisted zinc uptake pathway in rice remain uncertain. In particular, questions surround the form in which zinc from DMA is taken up [i.e. as free aqueous Zn(II) or as Zn(II)-DMA complexes] and the role of competitive behaviour of other metals with DMA. We propose that an accurate description of the effect of changes in pH, ligand concentration, and ionic strength on the stability of Zn(II)-DMA complexes in the presence of other metals in the microenvironment around root cells is critical for understanding the modus operandi of DMA during zinc uptake. To that end, we reveal the importance of geochemical changes in the microenvironment around root cells and demonstrate the effect of inaccurate stability constants on speciation models.
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Affiliation(s)
- George H R Northover
- Department of Earth Science and Engineering, Imperial College London, London, UK
| | | | - Dominik J Weiss
- Department of Earth Science and Engineering, Imperial College London, London, UK
- Department of Civil and Environmental Engineering, Princeton University, Princeton, NJ, USA
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