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Kühl M, Nielsen DA, Borisov SM. In Vivo Lifetime Imaging of the Internal O 2 Dynamics in Corals with near-Infrared-Emitting Sensor Nanoparticles. ACS Sens 2024. [PMID: 39179239 DOI: 10.1021/acssensors.4c01029] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/26/2024]
Abstract
Mapping of O2 with luminescent sensors within intact animals is challenging due to attenuation of excitation and emission light caused by tissue absorption and scattering as well as interfering background fluorescence. Here we show the application of luminescent O2 sensor nanoparticles (∼50-70 nm) composed of the O2 indicator platinum(II) tetra(4-fluoro)phenyltetrabenzoporphyrin (PtTPTBPF) immobilized in poly(methyl methacrylate-co-methacrylic acid) (PMMA-MA). We injected the sensor nanoparticles into the gastrovascular system of intact colony fractions of reef-building tropical corals that harbor photosynthetic microalgae in their tissues. The sensor nanoparticles are excited by red LED light (617 nm) and emit in the near-infrared (780 nm), which enhances the transmission of excitation and emission light through biological materials. This enabled us to map the internal O2 concentration via time-domain luminescence lifetime imaging through the outer tissue layers across several coral polyps in flowing seawater. After injection, nanoparticles dispersed within the coral tissue for several hours. While luminescence intensity imaging showed some local aggregation of sensor particles, lifetime imaging showed a more homogeneous O2 distribution across a larger area of the coral colony. Local stimulation of symbiont photosynthesis in corals induced oxygenation of illuminated tissue areas and formation of lateral O2 gradients toward surrounding respiring tissues, which were dissipated rapidly after the onset of darkness. Such measurements are key to improving our understanding of how corals regulate their internal chemical microenvironment and metabolic activity, and how they are affected by environmental stress such as ocean warming, acidification, and deoxygenation. Our experimental approach can also be adapted for in vivo O2 imaging in other natural systems such as biofilms, plant and animal tissues, as well as in organoids and other cell constructs, where imaging internal O2 conditions are relevant and challenging due to high optical density and background fluorescence.
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Affiliation(s)
- Michael Kühl
- Marine Biological Section, Department of Biology, University of Copenhagen, Strandpromenaden 5, 3000 Helsingør, Denmark
- Climate Change Cluster, University of Technology Sydney, Broadway 2007, Australia
| | | | - Sergey M Borisov
- Institute of Analytical Chemistry and Food Chemistry, Graz University of Technology, Stremayrgasse 9, A-8010 Graz, Austria
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Bartels N, Matthews JL, Lawson CA, Possell M, Hughes DJ, Raina JB, Suggett DJ. Paired metabolomics and volatilomics provides insight into transient high light stress response mechanisms of the coral Montipora mollis. Metabolomics 2024; 20:66. [PMID: 38886248 PMCID: PMC11182861 DOI: 10.1007/s11306-024-02136-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/28/2024] [Accepted: 05/27/2024] [Indexed: 06/20/2024]
Abstract
The coral holobiont is underpinned by complex metabolic exchanges between different symbiotic partners, which are impacted by environmental stressors. The chemical diversity of the compounds produced by the holobiont is high and includes primary and secondary metabolites, as well as volatiles. However, metabolites and volatiles have only been characterised in isolation so far. Here, we applied a paired metabolomic-volatilomic approach to characterise holistically the chemical response of the holobiont under stress. Montipora mollis fragments were subjected to high-light stress (8-fold higher than the controls) for 30 min. Photosystem II (PSII) photochemical efficiency values were 7-fold higher in control versus treatment corals immediately following high-light exposure, but returned to pre-stress levels after 30 min of recovery. Under high-light stress, we identified an increase in carbohydrates (> 5-fold increase in arabinose and fructose) and saturated fatty acids (7-fold increase in myristic and oleic acid), together with a decrease in fatty acid derivatives in both metabolites and volatiles (e.g., 80% decrease in oleamide and nonanal), and other antioxidants (~ 85% decrease in sorbitol and galactitol). These changes suggest short-term light stress induces oxidative stress. Correlation analysis between volatiles and metabolites identified positive links between sorbitol, galactitol, six other metabolites and 11 volatiles, with four of these compounds previously identified as antioxidants. This suggests that these 19 compounds may be related and share similar functions. Taken together, our findings demonstrate how paired metabolomics-volatilomics may illuminate broader metabolic shifts occurring under stress and identify linkages between uncharacterised compounds to putatively determine their functions.
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Affiliation(s)
- Natasha Bartels
- Climate Change Cluster, Faculty of Science, University of Technology Sydney, Ultimo, NSW, Australia.
| | - Jennifer L Matthews
- Climate Change Cluster, Faculty of Science, University of Technology Sydney, Ultimo, NSW, Australia
| | - Caitlin A Lawson
- Heron Island Research Station, Faculty of Science, University of Queensland, Gladstone, 4680, Australia
| | - Malcolm Possell
- School of Life and Environmental Sciences, University of Sydney, Sydney, NSW, Australia
| | - David J Hughes
- National Sea Simulator, Australian Institute of Marine Science, Townsville, QLD, Australia
| | - Jean-Baptiste Raina
- Climate Change Cluster, Faculty of Science, University of Technology Sydney, Ultimo, NSW, Australia
| | - David J Suggett
- KAUST Reefscape Restoration Initiative (KRRI) and Red Sea Research Center (RSRC), King Abdullah University of Science and Technology, Thuwal, Saudi Arabia
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Howard RD, Schul MD, Rodriguez Bravo LM, Altieri AH, Meyer JL. Shifts in the coral microbiome in response to in situ experimental deoxygenation. Appl Environ Microbiol 2023; 89:e0057723. [PMID: 37916820 PMCID: PMC10686059 DOI: 10.1128/aem.00577-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2023] [Accepted: 09/12/2023] [Indexed: 11/03/2023] Open
Abstract
IMPORTANCE Marine hypoxia is a threat for corals but has remained understudied in tropical regions where coral reefs are abundant. Though microbial symbioses can alleviate the effects of ecological stress, we do not yet understand the taxonomic or functional response of the coral microbiome to hypoxia. In this study, we experimentally lowered oxygen levels around Siderastrea siderea and Agaricia lamarcki colonies in situ to observe changes in the coral microbiome in response to deoxygenation. Our results show that hypoxia triggers a stochastic change of the microbiome overall, with some bacterial families changing deterministically after just 48 hours of exposure. These families represent an increase in anaerobic and opportunistic taxa in the microbiomes of both coral species. Thus, marine deoxygenation destabilizes the coral microbiome and increases bacterial opportunism. This work provides novel and fundamental knowledge of the microbial response in coral during hypoxia and may provide insight into holobiont function during stress.
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Affiliation(s)
- Rachel D. Howard
- Department of Soil, Water, and Ecosystem Sciences, University of Florida, Gainesville, Florida, USA
| | - Monica D. Schul
- Department of Soil, Water, and Ecosystem Sciences, University of Florida, Gainesville, Florida, USA
| | - Lucia M. Rodriguez Bravo
- Smithsonian Tropical Research Institute, Balboa, Ancon, Panama
- Red Sea Research Center, King Abdullah University of Science and Technology, Thuwal, Saudi Arabia
| | - Andrew H. Altieri
- Smithsonian Tropical Research Institute, Balboa, Ancon, Panama
- Department of Environmental Engineering Sciences, University of Florida, Gainesville, Florida, USA
| | - Julie L. Meyer
- Department of Soil, Water, and Ecosystem Sciences, University of Florida, Gainesville, Florida, USA
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Castrillón-Cifuentes AL, Zapata FA, Giraldo A, Wild C. Spatiotemporal variability of oxygen concentration in coral reefs of Gorgona Island (Eastern Tropical Pacific) and its effect on the coral Pocillopora capitata. PeerJ 2023; 11:e14586. [PMID: 36721774 PMCID: PMC9884479 DOI: 10.7717/peerj.14586] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2022] [Accepted: 11/28/2022] [Indexed: 01/27/2023] Open
Abstract
Dissolved oxygen concentration (DO) is one of the main factors limiting benthic species distribution. Due to ocean warming and eutrophication, the ocean is deoxygenating. In the Eastern Tropical Pacific (ETP), deep waters with low DO (<1 mg L-1) may reach coral reefs, because upwelling will likely intensify due to climate change. To understand oxygen variability and its effects on corals, we characterize the Spatio-temporal changes of DO in coral reefs of Gorgona Island and calculate the critical oxygen tension (P crit) to identify the DO concentration that could represent a hypoxic condition for Pocillopora capitata, one of the main reef-building species in the ETP. The mean (±SD) DO concentration in the coral reefs of Gorgona Island was 4.6 ± 0.89 mg L-1. Low DO conditions were due to upwelling, but hypoxia (<3.71 mg L-1, defined as a DO value 1 SD lower than the Mean) down to 3.0 mg O2 L-1 sporadically occurred at 10 m depth. The P crit of P. capitata was 3.7 mg L-1 and lies close to the hypoxic condition recorded on coral reefs during the upwelling season at 10 m depth. At Gorgona Island oxygen conditions lower than 2.3 mg L-1 occur at >20 m depth and coincide with the deepest bathymetric distribution of scattered colonies of Pocillopora. Because DO concentrations in coral reefs of Gorgona Island were comparably low to other coral reefs in the Eastern Tropical Pacific, and the hypoxic threshold of P. capitata was close to the minimum DO record on reefs, hypoxic events could represent a threat if conditions that promote eutrophication (and consequently hypoxia) increase.
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Affiliation(s)
- Ana Lucia Castrillón-Cifuentes
- Department of Marine Ecology/Faculty of Biology and Chemistry, Universität Bremen, Bremen, Germany,Departamento de Biología/Facultad de Ciencias Naturales y Exactas/Grupo de Investigación en Ecología de Arrecifes Coralinos, Universidad del Valle, Cali, Valle del Cauca, Colombia
| | - Fernando A. Zapata
- Departamento de Biología/Facultad de Ciencias Naturales y Exactas/Grupo de Investigación en Ecología de Arrecifes Coralinos, Universidad del Valle, Cali, Valle del Cauca, Colombia
| | - Alan Giraldo
- Departamento de Biología/Facultad de Ciencias Naturales y Exactas/Grupo de Investigación en Ciencias Oceanográficas, Universidad del Valle, Cali, Valle del Cauca, Colombia
| | - Christian Wild
- Department of Marine Ecology/Faculty of Biology and Chemistry, Universität Bremen, Bremen, Germany
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Lewis BM, Suggett DS, Prentis PJ, Nothdurft LD. Cellular adaptations leading to coral fragment attachment on artificial substrates in Acropora millepora (Am-CAM). Sci Rep 2022; 12:18431. [PMID: 36319668 PMCID: PMC9626494 DOI: 10.1038/s41598-022-23134-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2021] [Accepted: 10/25/2022] [Indexed: 11/18/2022] Open
Abstract
Reproductive propagation by asexual fragmentation in the reef-building coral Acropora millepora depends on (1) successful attachment to the reef substrate through modification of soft tissues and (2) a permanent bond with skeletal encrustation. Despite decades of research examining asexual propagation in corals, the initial response, cellular reorganisation, and development leading to fragment substrate attachment via a newly formed skeleton has not been documented in its entirety. Here, we establish the first "coral attachment model" for this species ("Am-CAM") by developing novel methods that allow correlation of fluorescence and electron microscopy image data with in vivo microscopic time-lapse imagery. This multi-scale imaging approach identified three distinct phases involved in asexual propagation: (1) the contact response of the coral fragment when contact with the substrate, followed by (2) fragment stabilisation through anchoring by the soft tissue, and (3) formation of a "lappet-like appendage" structure leading to substrate bonding of the tissue for encrustation through the onset of skeletal calcification. In developing Am-CAM, we provide new biological insights that can enable reef researchers, managers and coral restoration practitioners to begin evaluating attachment effectiveness, which is needed to optimise species-substrate compatibility and achieve effective outplanting.
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Affiliation(s)
- Brett M. Lewis
- grid.1024.70000000089150953School of Earth and Atmospheric Sciences, Faculty of Science, Queensland University of Technology, Brisbane, QLD Australia
| | - David S. Suggett
- grid.117476.20000 0004 1936 7611Climate Change Cluster (C3), University of Technology Sydney, Sydney, NSW Australia
| | - Peter J. Prentis
- grid.1024.70000000089150953Centre for Agriculture and Bioeconomy and School of Biology and Environmental Sciences, Faculty of Science, Queensland University of Technology, Brisbane, QLD Australia
| | - Luke D. Nothdurft
- grid.1024.70000000089150953School of Earth and Atmospheric Sciences, Faculty of Science, Queensland University of Technology, Brisbane, QLD Australia
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Alderdice R, Perna G, Cárdenas A, Hume BCC, Wolf M, Kühl M, Pernice M, Suggett DJ, Voolstra CR. Deoxygenation lowers the thermal threshold of coral bleaching. Sci Rep 2022; 12:18273. [PMID: 36316371 PMCID: PMC9622859 DOI: 10.1038/s41598-022-22604-3] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2022] [Accepted: 10/17/2022] [Indexed: 12/02/2022] Open
Abstract
Exposure to deoxygenation from climate warming and pollution is emerging as a contributing factor of coral bleaching and mortality. However, the combined effects of heating and deoxygenation on bleaching susceptibility remain unknown. Here, we employed short-term thermal stress assays to show that deoxygenated seawater can lower the thermal limit of an Acropora coral by as much as 1 °C or 0.4 °C based on bleaching index scores or dark-acclimated photosynthetic efficiencies, respectively. Using RNA-Seq, we show similar stress responses to heat with and without deoxygenated seawater, both activating putative key genes of the hypoxia-inducible factor response system indicative of cellular hypoxia. We also detect distinct deoxygenation responses, including a disruption of O2-dependent photo-reception/-protection, redox status, and activation of an immune response prior to the onset of bleaching. Thus, corals are even more vulnerable when faced with heat stress in deoxygenated waters. This highlights the need to integrate dissolved O2 measurements into global monitoring programs of coral reefs.
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Affiliation(s)
- Rachel Alderdice
- Climate Change Cluster, Faculty of Science, University of Technology Sydney, Ultimo, NSW, 2007, Australia.
- Department of Biology, University of Konstanz, 78457, Konstanz, Germany.
| | - Gabriela Perna
- Department of Biology, University of Konstanz, 78457, Konstanz, Germany
| | - Anny Cárdenas
- Department of Biology, University of Konstanz, 78457, Konstanz, Germany
| | - Benjamin C C Hume
- Department of Biology, University of Konstanz, 78457, Konstanz, Germany
| | - Martin Wolf
- Department of Biology, University of Konstanz, 78457, Konstanz, Germany
| | - Michael Kühl
- Marine Biology Section, Department of Biology, University of Copenhagen, Strandpromenaden 5, 3000, Helsingør, Denmark
| | - Mathieu Pernice
- Climate Change Cluster, Faculty of Science, University of Technology Sydney, Ultimo, NSW, 2007, Australia
| | - David J Suggett
- Climate Change Cluster, Faculty of Science, University of Technology Sydney, Ultimo, NSW, 2007, Australia
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