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MacVittie S, Doroodian S, Alberto A, Sogin M. Microbiome depletion and recovery in the sea anemone, Exaiptasia diaphana, following antibiotic exposure. mSystems 2024; 9:e0134223. [PMID: 38757963 PMCID: PMC11237641 DOI: 10.1128/msystems.01342-23] [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: 12/11/2023] [Accepted: 04/19/2024] [Indexed: 05/18/2024] Open
Abstract
Microbial species that comprise host-associated microbiomes play an essential role in maintaining and mediating the health of plants and animals. While defining the role of individual or even complex communities is important toward quantifying the effect of the microbiome on host health, it is often challenging to develop causal studies that link microbial populations to changes in host fitness. Here, we investigated the impacts of reduced microbial load following antibiotic exposure on the fitness of the anemone, Exaiptasia diaphana and subsequent recovery of the host's microbiome. Anemones were exposed to two different types of antibiotic solutions for 3 weeks and subsequently held in sterilized seawater for a 3-week recovery period. Our results revealed that both antibiotic treatments reduced the overall microbial load during and up to 1 week post-treatment. The observed reduction in microbial load was coupled with reduced anemone biomass, halted asexual reproduction rates, and for one of the antibiotic treatments, the partial removal of the anemone's algal symbiont. Finally, our amplicon sequencing results of the 16S rRNA gene revealed that anemone bacterial composition only shifted in treated individuals during the recovery phase of the experiment, where we also observed a significant reduction in the overall diversity of the microbial community. Our work implies that the E. diaphana's microbiome contributes to host fitness and that the recovery of the host's microbiome following disturbance with antibiotics leads to a reduced, but stable microbial state.IMPORTANCEExaiptasia diaphana is an emerging model used to define the cellular and molecular mechanisms of coral-algal symbioses. E. diaphana also houses a diverse microbiome, consisting of hundreds of microbial partners with undefined function. Here, we applied antibiotics to quantify the impact of microbiome removal on host fitness as well as define trajectories in microbiome recovery following disturbance. We showed that reduction of the microbiome leads to negative impacts on host fitness, and that the microbiome does not recover to its original composition while held under aseptic conditions. Rather the microbiome becomes less diverse, but more consistent across individuals. Our work is important because it suggests that anemone microbiomes play a role in maintaining host fitness, that they are susceptible to disturbance events, and that it is possible to generate gnotobiotic individuals that can be leveraged in microbiome manipulation studies to investigate the role of individual species on host health.
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Affiliation(s)
- Sophie MacVittie
- Department of Molecular Cell Biology, University of California, Merced, California, USA
| | - Saam Doroodian
- Department of Molecular Cell Biology, University of California, Merced, California, USA
| | - Aaron Alberto
- Department of Molecular Cell Biology, University of California, Merced, California, USA
| | - Maggie Sogin
- Department of Molecular Cell Biology, University of California, Merced, California, USA
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2
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Tran C, Rosenfield GR, Cleves PA, Krediet CJ, Paul MR, Clowez S, Grossman AR, Pringle JR. Photosynthesis and other factors affecting the establishment and maintenance of cnidarian-dinoflagellate symbiosis. Philos Trans R Soc Lond B Biol Sci 2024; 379:20230079. [PMID: 38497261 PMCID: PMC10945401 DOI: 10.1098/rstb.2023.0079] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2023] [Accepted: 02/07/2024] [Indexed: 03/19/2024] Open
Abstract
Coral growth depends on the partnership between the animal hosts and their intracellular, photosynthetic dinoflagellate symbionts. In this study, we used the sea anemone Aiptasia, a laboratory model for coral biology, to investigate the poorly understood mechanisms that mediate symbiosis establishment and maintenance. We found that initial colonization of both adult polyps and larvae by a compatible algal strain was more effective when the algae were able to photosynthesize and that the long-term maintenance of the symbiosis also depended on photosynthesis. In the dark, algal cells were taken up into host gastrodermal cells and not rapidly expelled, but they seemed unable to reproduce and thus were gradually lost. When we used confocal microscopy to examine the interaction of larvae with two algal strains that cannot establish stable symbioses with Aiptasia, it appeared that both pre- and post-phagocytosis mechanisms were involved. With one strain, algae entered the gastric cavity but appeared to be completely excluded from the gastrodermal cells. With the other strain, small numbers of algae entered the gastrodermal cells but appeared unable to proliferate there and were slowly lost upon further incubation. We also asked if the exclusion of either incompatible strain could result simply from their cells' being too large for the host cells to accommodate. However, the size distributions of the compatible and incompatible strains overlapped extensively. Moreover, examination of macerates confirmed earlier reports that individual gastrodermal cells could expand to accommodate multiple algal cells. This article is part of the theme issue 'Sculpting the microbiome: how host factors determine and respond to microbial colonization'.
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Affiliation(s)
- Cawa Tran
- Department of Genetics, Stanford University School of Medicine, Stanford CA 94305, USA
- Department of Biology, University of San Diego, San Diego, CA 92110, USA
| | - Gabriel R. Rosenfield
- Department of Genetics, Stanford University School of Medicine, Stanford CA 94305, USA
| | - Phillip A. Cleves
- Department of Genetics, Stanford University School of Medicine, Stanford CA 94305, USA
| | - Cory J. Krediet
- Department of Genetics, Stanford University School of Medicine, Stanford CA 94305, USA
| | - Maitri R. Paul
- Department of Genetics, Stanford University School of Medicine, Stanford CA 94305, USA
| | - Sophie Clowez
- Department of Plant Biology, Carnegie Institution for Science, Stanford, CA 94305, USA
| | - Arthur R. Grossman
- Department of Plant Biology, Carnegie Institution for Science, Stanford, CA 94305, USA
| | - John R. Pringle
- Department of Genetics, Stanford University School of Medicine, Stanford CA 94305, USA
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3
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Chen H, Sosa A, Chen F. Growth and Cell Size of Microalga Auxenochlorella protothecoides AS-1 under Different Trophic Modes. Microorganisms 2024; 12:835. [PMID: 38674779 PMCID: PMC11052296 DOI: 10.3390/microorganisms12040835] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2024] [Revised: 04/11/2024] [Accepted: 04/19/2024] [Indexed: 04/28/2024] Open
Abstract
Certain microalgal species can grow with different trophic strategies depending on the availability of nutrient resources. They can use the energy from light or an organic substrate, or both, and can therefore be called autotrophs, heterotrophs, or mixotrophs. We recently isolated a microalgal strain from the microplastic biofilm, which was identified as Auxenochlorella protothecoides, AS-1. Strain AS-1 grew rapidly in bacterial culture media and exhibited different growth rates and cell sizes under different trophic conditions. We compared the growth performance of AS-1 under the three different trophic modes. AS-1 reached a high biomass (>4 g/L) in 6 days under mixotrophic growth conditions with a few organic carbons as a substrate. In contrast, poor autotrophic growth was observed for AS-1. Different cell sizes, including daughter and mother cells, were observed under the different growth modes. We applied a Coulter Counter to measure the size distribution patterns of AS-1 under different trophic modes. We showed that the cell size distribution of AS-1 was affected by different growth modes. Compared to the auto-, hetero- and mixotrophic modes, AS-1 achieved higher biomass productivity by increasing cell number and cell size in the presence of organic substrate. The mechanisms and advantages of having more mother cells with organic substrates are still unclear and warrant further investigations. The work here provides the growth information of a newly isolated A. protothecoides AS-1 which will be beneficial to future downstream applications.
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Affiliation(s)
- Haoyu Chen
- Institute of Marine & Environmental Technology, University of Maryland Center for Environmental Science, Baltimore, MD 21613, USA; (H.C.); (A.S.)
| | - Ana Sosa
- Institute of Marine & Environmental Technology, University of Maryland Center for Environmental Science, Baltimore, MD 21613, USA; (H.C.); (A.S.)
- Maryland Sea Grant College, University of Maryland Center for Environmental Science, Cambridge, MD 21613, USA
| | - Feng Chen
- Institute of Marine & Environmental Technology, University of Maryland Center for Environmental Science, Baltimore, MD 21613, USA; (H.C.); (A.S.)
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4
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Allen-Waller LR, Jones KG, Martynek MP, Brown KT, Barott KL. Comparative physiology reveals heat stress disrupts acid-base homeostasis independent of symbiotic state in the model cnidarian Exaiptasia diaphana. J Exp Biol 2024; 227:jeb246222. [PMID: 38269486 PMCID: PMC10911193 DOI: 10.1242/jeb.246222] [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: 05/31/2023] [Accepted: 01/17/2024] [Indexed: 01/26/2024]
Abstract
Climate change threatens the survival of symbiotic cnidarians by causing photosymbiosis breakdown in a process known as bleaching. Direct effects of temperature on cnidarian host physiology remain difficult to describe because heatwaves depress symbiont performance, leading to host stress and starvation. The symbiotic sea anemone Exaiptasia diaphana provides an opportune system to disentangle direct versus indirect heat effects on the host, as it can survive indefinitely without symbionts. We tested the hypothesis that heat directly impairs cnidarian physiology by comparing symbiotic and aposymbiotic individuals of two laboratory subpopulations of a commonly used clonal strain of E. diaphana, CC7. We exposed anemones to a range of temperatures (ambient, +2°C, +4°C and +6°C) for 15-18 days, then measured their symbiont population densities, autotrophic carbon assimilation and translocation, photosynthesis, respiration and host intracellular pH (pHi). Symbiotic anemones from the two subpopulations differed in size and symbiont density and exhibited distinct heat stress responses, highlighting the importance of acclimation to different laboratory conditions. Specifically, the cohort with higher initial symbiont densities experienced dose-dependent symbiont loss with increasing temperature and a corresponding decline in host photosynthate accumulation. In contrast, the cohort with lower initial symbiont densities did not lose symbionts or assimilate less photosynthate when heated, similar to the response of aposymbiotic anemones. However, anemone pHi decreased at higher temperatures regardless of cohort, symbiont presence or photosynthate translocation, indicating that heat consistently disrupts cnidarian acid-base homeostasis independent of symbiotic status or mutualism breakdown. Thus, pH regulation may be a critical vulnerability for cnidarians in a changing climate.
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Affiliation(s)
| | - Katelyn G. Jones
- Department of Biology, University of Pennsylvania, Philadelphia, PA 19104, USA
| | | | - Kristen T. Brown
- Department of Biology, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Katie L. Barott
- Department of Biology, University of Pennsylvania, Philadelphia, PA 19104, USA
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5
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Anthony CJ, Lock C, Bentlage B. Rapid, high-throughput phenotypic profiling of endosymbiotic dinoflagellates (Symbiodiniaceae) using benchtop flow cytometry. PLoS One 2023; 18:e0290649. [PMID: 37708174 PMCID: PMC10501577 DOI: 10.1371/journal.pone.0290649] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2022] [Accepted: 08/05/2023] [Indexed: 09/16/2023] Open
Abstract
Endosymbiotic dinoflagellates (Family Symbiodiniaceae) are the primary producer of energy for many cnidarians, including corals. The intricate coral-dinoflagellate symbiotic relationship is becoming increasingly important under climate change, as its breakdown leads to mass coral bleaching and often mortality. Despite methodological progress, assessing the phenotypic traits of Symbiodiniaceae in-hospite remains a complex task. Bio-optics, biochemistry, or "-omics" techniques are expensive, often inaccessible to investigators, or lack the resolution required to understand single-cell phenotypic states within endosymbiotic dinoflagellate assemblages. To help address this issue, we developed a protocol that collects information on cell autofluorescence, shape, and size to simultaneously generate phenotypic profiles for thousands of Symbiodiniaceae cells, thus revealing phenotypic variance of the Symbiodiniaceae assemblage to the resolution of single cells. As flow cytometry is adopted as a robust and efficient method for cell counting, integration of our protocol into existing workflows allows researchers to acquire a new level of resolution for studies examining the acclimation and adaptation strategies of Symbiodiniaceae assemblages.
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Affiliation(s)
| | - Colin Lock
- Marine Laboratory, University of Guam, Mangilao, Guam, United States of America
| | - Bastian Bentlage
- Marine Laboratory, University of Guam, Mangilao, Guam, United States of America
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6
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Symbiotic dinoflagellates divert energy away from mutualism during coral bleaching recovery. Symbiosis 2023. [DOI: 10.1007/s13199-023-00901-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
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7
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Walker NS, Cornwell BH, Nestor V, Armstrong KC, Golbuu Y, Palumbi SR. Persistence of phenotypic responses to short-term heat stress in the tabletop coral Acropora hyacinthus. PLoS One 2022; 17:e0269206. [PMID: 36084033 PMCID: PMC9462741 DOI: 10.1371/journal.pone.0269206] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2022] [Accepted: 08/23/2022] [Indexed: 12/26/2022] Open
Abstract
Widespread mapping of coral thermal resilience is essential for developing effective management strategies and requires replicable and rapid multi-location assays of heat resistance and recovery. One- or two-day short-term heat stress experiments have been previously employed to assess heat resistance, followed by single assays of bleaching condition. We tested the reliability of short-term heat stress resistance, and linked resistance and recovery assays, by monitoring the phenotypic response of fragments from 101 Acropora hyacinthus colonies located in Palau (Micronesia) to short-term heat stress. Following short-term heat stress, bleaching and mortality were recorded after 16 hours, daily for seven days, and after one and two months of recovery. To follow corals over time, we utilized a qualitative, non-destructive visual bleaching score metric that correlated with standard symbiont retention assays. The bleaching state of coral fragments 16 hours post-heat stress was highly indicative of their state over the next 7 days, suggesting that symbiont population sizes within corals may quickly stabilize post-heat stress. Bleaching 16 hours post-heat stress predicted likelihood of mortality over the subsequent 3–5 days, after which there was little additional mortality. Together, bleaching and mortality suggested that rapid assays of the phenotypic response following short-term heat stress were good metrics of the total heat treatment effect. Additionally, our data confirm geographic patterns of intraspecific variation in Palau and show that bleaching severity among colonies was highly correlated with mortality over the first week post-stress. We found high survival (98%) and visible recovery (100%) two months after heat stress among coral fragments that survived the first week post-stress. These findings help simplify rapid, widespread surveys of heat sensitivity in Acropora hyacinthus by showing that standardized short-term experiments can be confidently assayed after 16 hours, and that bleaching sensitivity may be linked to subsequent survival using experimental assessments.
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Affiliation(s)
- Nia S. Walker
- Department of Biology, Hopkins Marine Station of Stanford University, Pacific Grove, California, United States of America
- * E-mail:
| | - Brendan H. Cornwell
- Department of Biology, Hopkins Marine Station of Stanford University, Pacific Grove, California, United States of America
| | | | - Katrina C. Armstrong
- Department of Biology, Hopkins Marine Station of Stanford University, Pacific Grove, California, United States of America
| | | | - Stephen R. Palumbi
- Department of Biology, Hopkins Marine Station of Stanford University, Pacific Grove, California, United States of America
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8
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Cui G, Liew YJ, Konciute MK, Zhan Y, Hung SH, Thistle J, Gastoldi L, Schmidt-Roach S, Dekker J, Aranda M. Nutritional control regulates symbiont proliferation and life history in coral-dinoflagellate symbiosis. BMC Biol 2022; 20:103. [PMID: 35549698 PMCID: PMC9102920 DOI: 10.1186/s12915-022-01306-2] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2021] [Accepted: 04/22/2022] [Indexed: 12/18/2022] Open
Abstract
Background The coral-Symbiodiniaceae symbiosis is fundamental for the coral reef ecosystem. Corals provide various inorganic nutrients to their algal symbionts in exchange for the photosynthates to meet their metabolic demands. When becoming symbionts, Symbiodiniaceae cells show a reduced proliferation rate and a different life history. While it is generally believed that the animal hosts play critical roles in regulating these processes, far less is known about the molecular underpinnings that allow the corals to induce the changes in their symbionts. Results We tested symbiont cell proliferation and life stage changes in vitro in response to different nutrient-limiting conditions to determine the key nutrients and to compare the respective symbiont transcriptomic profiles to cells in hospite. We then examined the effects of nutrient repletion on symbiont proliferation in coral hosts and quantified life stage transitions in vitro using time-lapse confocal imaging. Here, we show that symbionts in hospite share gene expression and pathway activation profiles with free-living cells under nitrogen-limited conditions, strongly suggesting that symbiont proliferation in symbiosis is limited by nitrogen availability. Conclusions We demonstrate that nitrogen limitation not only suppresses cell proliferation but also life stage transition to maintain symbionts in the immobile coccoid stage. Nutrient repletion experiments in corals further confirmed that nitrogen availability is the major factor limiting symbiont density in hospite. Our study emphasizes the importance of nitrogen in coral-algae interactions and, more importantly, sheds light on the crucial role of nitrogen in symbiont life history regulation. Supplementary Information The online version contains supplementary material available at 10.1186/s12915-022-01306-2.
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Affiliation(s)
- Guoxin Cui
- Biological and Environmental Sciences and Engineering Division (BESE), Red Sea Research Center (RSRC), King Abdullah University of Science and Technology (KAUST), Thuwal, Saudi Arabia.
| | - Yi Jin Liew
- Biological and Environmental Sciences and Engineering Division (BESE), Red Sea Research Center (RSRC), King Abdullah University of Science and Technology (KAUST), Thuwal, Saudi Arabia
| | - Migle K Konciute
- Biological and Environmental Sciences and Engineering Division (BESE), Red Sea Research Center (RSRC), King Abdullah University of Science and Technology (KAUST), Thuwal, Saudi Arabia
| | - Ye Zhan
- Program in Systems Biology, Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, MA, USA
| | - Shiou-Han Hung
- Biological and Environmental Sciences and Engineering Division (BESE), Red Sea Research Center (RSRC), King Abdullah University of Science and Technology (KAUST), Thuwal, Saudi Arabia
| | - Jana Thistle
- Biological and Environmental Sciences and Engineering Division (BESE), Red Sea Research Center (RSRC), King Abdullah University of Science and Technology (KAUST), Thuwal, Saudi Arabia
| | - Lucia Gastoldi
- Biological and Environmental Sciences and Engineering Division (BESE), Red Sea Research Center (RSRC), King Abdullah University of Science and Technology (KAUST), Thuwal, Saudi Arabia
| | - Sebastian Schmidt-Roach
- Biological and Environmental Sciences and Engineering Division (BESE), Red Sea Research Center (RSRC), King Abdullah University of Science and Technology (KAUST), Thuwal, Saudi Arabia
| | - Job Dekker
- Program in Systems Biology, Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, MA, USA.,Howard Hughes Medical Institute, Chevy Chase, MD, USA
| | - Manuel Aranda
- Biological and Environmental Sciences and Engineering Division (BESE), Red Sea Research Center (RSRC), King Abdullah University of Science and Technology (KAUST), Thuwal, Saudi Arabia.
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9
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Vuckovic D, Tinoco AI, Ling L, Renicke C, Pringle JR, Mitch WA. Conversion of oxybenzone sunscreen to phototoxic glucoside conjugates by sea anemones and corals. Science 2022; 376:644-648. [PMID: 35511969 DOI: 10.1126/science.abn2600] [Citation(s) in RCA: 41] [Impact Index Per Article: 20.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
The reported toxicity of oxybenzone-based sunscreens to corals has raised concerns about the impacts of ecotourist-shed sunscreens on corals already weakened by global stressors. However, oxybenzone's toxicity mechanism(s) are not understood, hampering development of safer sunscreens. We found that oxybenzone caused high mortality of a sea anemone under simulated sunlight including ultraviolet (UV) radiation (290 to 370 nanometers). Although oxybenzone itself protected against UV-induced photo-oxidation, both the anemone and a mushroom coral formed oxybenzone-glucoside conjugates that were strong photo-oxidants. Algal symbionts sequestered these conjugates, and mortality correlated with conjugate concentrations in animal cytoplasm. Higher mortality in anemones that lacked symbionts suggests an enhanced risk from oxybenzone to corals bleached by rising temperatures. Because many commercial sunscreens contain structurally related chemicals, understanding metabolite phototoxicity should facilitate the development of coral-safe products.
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Affiliation(s)
- Djordje Vuckovic
- Department of Civil and Environmental Engineering, Stanford University, Stanford, CA, USA
| | - Amanda I Tinoco
- Department of Genetics, Stanford University School of Medicine, Stanford, CA, USA
| | - Lorraine Ling
- Department of Genetics, Stanford University School of Medicine, Stanford, CA, USA
| | - Christian Renicke
- Department of Genetics, Stanford University School of Medicine, Stanford, CA, USA
| | - John R Pringle
- Department of Genetics, Stanford University School of Medicine, Stanford, CA, USA
| | - William A Mitch
- Department of Civil and Environmental Engineering, Stanford University, Stanford, CA, USA
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10
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Hong JK, Kim SB, Ahn SH, Choi Y, Lee TK. Flow cytometric monitoring of the bacterial phenotypic diversity in aquatic ecosystems. J Microbiol 2021; 59:879-885. [PMID: 34554452 DOI: 10.1007/s12275-021-1443-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2021] [Revised: 09/15/2021] [Accepted: 09/15/2021] [Indexed: 11/30/2022]
Abstract
Flow cytometry is a promising tool used to identify the phenotypic features of bacterial communities in aquatic ecosystems by measuring the physical and chemical properties of cells based on their light scattering behavior and fluorescence. Compared to molecular or culture-based approaches, flow cytometry is suitable for the online monitoring of microbial water quality because of its relatively simple sample preparation process, rapid analysis time, and high-resolution phenotypic data. Advanced statistical techniques (e.g., denoising and binning) can be utilized to successfully calculate phenotypic diversity by processing the scatter data obtained from flow cytometry. These phenotypic diversities were well correlated with taxonomic-based diversity computed using next-generation 16S RNA gene sequencing. The protocol provided in this paper should be a useful guide for a fast and reliable flow cytometric monitoring of bacterial phenotypic diversity in aquatic ecosystems.
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Affiliation(s)
- Jin-Kyung Hong
- Department of Environmental and Energy Engineering, Yonsei University, Wonju, 26493, Republic of Korea
| | - Soo Bin Kim
- Department of Environmental and Energy Engineering, Yonsei University, Wonju, 26493, Republic of Korea
| | - Seok Hyun Ahn
- Department of Environmental and Energy Engineering, Yonsei University, Wonju, 26493, Republic of Korea
| | - Yongjoo Choi
- Research Institute for Global Change, Japan Agency for Marine-Earth Science and Technology, Yokohama, 236-0001, Japan
| | - Tae Kwon Lee
- Department of Environmental and Energy Engineering, Yonsei University, Wonju, 26493, Republic of Korea.
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11
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Cornwell B, Armstrong K, Walker NS, Lippert M, Nestor V, Golbuu Y, Palumbi SR. Widespread variation in heat tolerance and symbiont load are associated with growth tradeoffs in the coral Acropora hyacinthus in Palau. eLife 2021; 10:64790. [PMID: 34387190 PMCID: PMC8457836 DOI: 10.7554/elife.64790] [Citation(s) in RCA: 28] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2020] [Accepted: 08/06/2021] [Indexed: 12/20/2022] Open
Abstract
Climate change is dramatically changing ecosystem composition and productivity, leading scientists to consider the best approaches to map natural resistance and foster ecosystem resilience in the face of these changes. Here, we present results from a large-scale experimental assessment of coral bleaching resistance, a critical trait for coral population persistence as oceans warm, in 221 colonies of the coral Acropora hyacinthus across 37 reefs in Palau. We find that bleaching-resistant individuals inhabit most reefs but are found more often in warmer microhabitats. Our survey also found wide variation in symbiont concentration among colonies, and that colonies with lower symbiont load tended to be more bleaching-resistant. By contrast, our data show that low symbiont load comes at the cost of lower growth rate, a tradeoff that may operate widely among corals across environments. Corals with high bleaching resistance have been suggested as a source for habitat restoration or selective breeding in order to increase coral reef resilience to climate change. Our maps show where these resistant corals can be found, but the existence of tradeoffs with heat resistance may suggest caution in unilateral use of this one trait in restoration.
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Affiliation(s)
- Brendan Cornwell
- Department of Biology, Hopkins Marine Station of Stanford University, Pacific Grove, United States
| | - Katrina Armstrong
- Department of Biology, Hopkins Marine Station of Stanford University, Pacific Grove, United States
| | - Nia S Walker
- Department of Biology, Hopkins Marine Station of Stanford University, Pacific Grove, United States
| | - Marilla Lippert
- Department of Biology, Hopkins Marine Station of Stanford University, Pacific Grove, United States
| | - Victor Nestor
- Research, Palau International Coral Reef Center, Koror, Palau
| | - Yimnang Golbuu
- Director, Palau International Coral Reef Center, Koror, Palau
| | - Stephen R Palumbi
- Department of Biology, Hopkins Marine Station of Stanford University, Pacific Grove, United States
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12
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McLachlan RH, Dobson KL, Schmeltzer ER, Vega Thurber R, Grottoli AG. A review of coral bleaching specimen collection, preservation, and laboratory processing methods. PeerJ 2021; 9:e11763. [PMID: 34285838 PMCID: PMC8272927 DOI: 10.7717/peerj.11763] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2021] [Accepted: 06/21/2021] [Indexed: 12/02/2022] Open
Abstract
Under current climate warming predictions, the future of coral reefs is dire. With projected coral reef decline, it is likely that coral specimens for bleaching research will increasingly become a more limited resource in the future. By adopting a holistic approach through increased collaborations, coral bleaching scientists can maximize a specimen’s investigative yield, thus reducing the need to remove more coral material from the reef. Yet to expand a specimen’s utility for additional analytic methods, information on how corals are collected is essential as many methods are variably sensitive to upstream handling and processing. In an effort to identify common practices for coral collection, sacrifice, preservation, and processing in coral bleaching research, we surveyed the literature from the last 6.5 years and created and analyzed the resulting dataset of 171 publications. Since January 2014, at least 21,890 coral specimens were collected for bleaching surveys or bleaching experiments. These specimens spanned 122 species of scleractinian corals where the most frequently sampled were Acropora millepora, Pocillopora damicornis, and Stylophora pistillata. Almost 90% of studies removed fragments from the reef, 6% collected skeletal cores, and 3% collected mucus specimens. The most common methods for sacrificing specimens were snap freezing with liquid nitrogen, chemical preservation (e.g., with ethanol or nucleic acid stabilizing buffer), or airbrushing live fragments. We also characterized 37 distinct methodological pathways from collection to processing of specimens in preparation for a variety of physiological, -omic, microscopy, and imaging analyses. Interestingly, almost half of all studies used only one of six different pathways. These similarities in collection, preservation, and processing methods illustrate that archived coral specimens could be readily shared among researchers for additional analyses. In addition, our review provides a reference for future researchers who are considering which methodological pathway to select to maximize the utility of coral bleaching specimens that they collect.
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Affiliation(s)
- Rowan H McLachlan
- School of Earth Sciences, Ohio State University, Columbus, OH, United States of America
| | - Kerri L Dobson
- School of Earth Sciences, Ohio State University, Columbus, OH, United States of America
| | - Emily R Schmeltzer
- Department of Microbiology, Oregon State University, Corvallis, OR, United States of America
| | - Rebecca Vega Thurber
- Department of Microbiology, Oregon State University, Corvallis, OR, United States of America
| | - Andréa G Grottoli
- School of Earth Sciences, Ohio State University, Columbus, OH, United States of America
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13
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Innis T, Allen-Waller L, Brown KT, Sparagon W, Carlson C, Kruse E, Huffmyer AS, Nelson CE, Putnam HM, Barott KL. Marine heatwaves depress metabolic activity and impair cellular acid-base homeostasis in reef-building corals regardless of bleaching susceptibility. GLOBAL CHANGE BIOLOGY 2021; 27:2728-2743. [PMID: 33784420 DOI: 10.1111/gcb.15622] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/23/2021] [Revised: 03/18/2021] [Accepted: 03/21/2021] [Indexed: 06/12/2023]
Abstract
Ocean warming is causing global coral bleaching events to increase in frequency, resulting in widespread coral mortality and disrupting the function of coral reef ecosystems. However, even during mass bleaching events, many corals resist bleaching despite exposure to abnormally high temperatures. While the physiological effects of bleaching have been well documented, the consequences of heat stress for bleaching-resistant individuals are not well understood. In addition, much remains to be learned about how heat stress affects cellular-level processes that may be overlooked at the organismal level, yet are crucial for coral performance in the short term and ecological success over the long term. Here we compared the physiological and cellular responses of bleaching-resistant and bleaching-susceptible corals throughout the 2019 marine heatwave in Hawai'i, a repeat bleaching event that occurred 4 years after the previous regional event. Relative bleaching susceptibility within species was consistent between the two bleaching events, yet corals of both resistant and susceptible phenotypes exhibited pronounced metabolic depression during the heatwave. At the cellular level, bleaching-susceptible corals had lower intracellular pH than bleaching-resistant corals at the peak of bleaching for both symbiont-hosting and symbiont-free cells, indicating greater disruption of acid-base homeostasis in bleaching-susceptible individuals. Notably, cells from both phenotypes were unable to compensate for experimentally induced cellular acidosis, indicating that acid-base regulation was significantly impaired at the cellular level even in bleaching-resistant corals and in cells containing symbionts. Thermal disturbances may thus have substantial ecological consequences, as even small reallocations in energy budgets to maintain homeostasis during stress can negatively affect fitness. These results suggest concern is warranted for corals coping with ocean acidification alongside ocean warming, as the feedback between temperature stress and acid-base regulation may further exacerbate the physiological effects of climate change.
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Affiliation(s)
- Teegan Innis
- Department of Biology, University of Pennsylvania, Philadelphia, PA, USA
| | | | - Kristen T Brown
- Department of Biology, University of Pennsylvania, Philadelphia, PA, USA
- ARC Centre of Excellence for Coral Reef Studies and School of Biological Sciences, University of Queensland, St. Lucia, Qld, Australia
| | - Wesley Sparagon
- Daniel K. Inouye Center for Microbial Oceanography: Research and Education, Department of Oceanography and Sea Grant College Program, University of Hawai'i at Mānoa, Honolulu, HI, USA
| | | | - Elisa Kruse
- Department of Biology, University of Pennsylvania, Philadelphia, PA, USA
| | - Ariana S Huffmyer
- Department of Biological Sciences, University of Rhode Island, Kingston, RI, USA
| | - Craig E Nelson
- Daniel K. Inouye Center for Microbial Oceanography: Research and Education, Department of Oceanography and Sea Grant College Program, University of Hawai'i at Mānoa, Honolulu, HI, USA
| | - Hollie M Putnam
- Department of Biological Sciences, University of Rhode Island, Kingston, RI, USA
| | - Katie L Barott
- Department of Biology, University of Pennsylvania, Philadelphia, PA, USA
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14
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Clowez S, Renicke C, Pringle JR, Grossman AR. Impact of Menthol on Growth and Photosynthetic Function of Breviolum Minutum (Dinoflagellata, Dinophyceae, Symbiodiniaceae) and Interactions with its Aiptasia Host. JOURNAL OF PHYCOLOGY 2021; 57:245-257. [PMID: 33025575 DOI: 10.1111/jpy.13081] [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: 06/01/2019] [Revised: 09/01/2020] [Accepted: 09/19/2020] [Indexed: 06/11/2023]
Abstract
Environmental change, including global warming and chemical pollution, can compromise cnidarian-(e.g., coral-) dinoflagellate symbioses and cause coral bleaching. Understanding the mechanisms that regulate these symbioses will inform strategies for sustaining healthy coral-reef communities. A model system for corals is the symbiosis between the sea anemone Exaiptasia pallida (common name Aiptasia) and its dinoflagellate partners (family Symbiodiniaceae). To complement existing studies of the interactions between these organisms, we examined the impact of menthol, a reagent often used to render cnidarians aposymbiotic, on the dinoflagellate Breviolum minutum, both in culture and in hospite. In both environments, the growth and photosynthesis of this alga were compromised at either 100 or 300 µM menthol. We observed reduction in PSII and PSI functions, the abundances of reaction-center proteins, and, at 300 µM menthol, of total cellular proteins. Interestingly, for free-living algae exposed to 100 µM menthol, an initial decline in growth, photosynthetic activities, pigmentation, and protein abundances reversed after 5-15 d, eventually approaching control levels. This behavior was observed in cells maintained in continuous light, but not in cells experiencing a light-dark regimen, suggesting that B. minutum can detoxify menthol or acclimate and repair damaged photosynthetic complexes in a light- and/or energy-dependent manner. Extended exposures of cultured algae to 300 µM menthol ultimately resulted in algal death. Most symbiotic anemones were also unable to survive this menthol concentration for 30 d. Additionally, cells impaired for photosynthesis by pre-treatment with 300 µM menthol exhibited reduced efficiency in re-populating the anemone host.
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Affiliation(s)
- Sophie Clowez
- Department of Plant Biology, Carnegie Institution for Science, 260 Panama Street, Stanford, California, 94305, USA
| | - Christian Renicke
- Department of Genetics, Stanford University, Stanford, California, 94305, USA
| | - John R Pringle
- Department of Genetics, Stanford University, Stanford, California, 94305, USA
| | - Arthur R Grossman
- Department of Plant Biology, Carnegie Institution for Science, 260 Panama Street, Stanford, California, 94305, USA
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15
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Cleves PA, Krediet CJ, Lehnert EM, Onishi M, Pringle JR. Insights into coral bleaching under heat stress from analysis of gene expression in a sea anemone model system. Proc Natl Acad Sci U S A 2020; 117:28906-28917. [PMID: 33168733 PMCID: PMC7682557 DOI: 10.1073/pnas.2015737117] [Citation(s) in RCA: 36] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Loss of endosymbiotic algae ("bleaching") under heat stress has become a major problem for reef-building corals worldwide. To identify genes that might be involved in triggering or executing bleaching, or in protecting corals from it, we used RNAseq to analyze gene-expression changes during heat stress in a coral relative, the sea anemone Aiptasia. We identified >500 genes that showed rapid and extensive up-regulation upon temperature increase. These genes fell into two clusters. In both clusters, most genes showed similar expression patterns in symbiotic and aposymbiotic anemones, suggesting that this early stress response is largely independent of the symbiosis. Cluster I was highly enriched for genes involved in innate immunity and apoptosis, and most transcript levels returned to baseline many hours before bleaching was first detected, raising doubts about their possible roles in this process. Cluster II was highly enriched for genes involved in protein folding, and most transcript levels returned more slowly to baseline, so that roles in either promoting or preventing bleaching seem plausible. Many of the genes in clusters I and II appear to be targets of the transcription factors NFκB and HSF1, respectively. We also examined the behavior of 337 genes whose much higher levels of expression in symbiotic than aposymbiotic anemones in the absence of stress suggest that they are important for the symbiosis. Unexpectedly, in many cases, these expression levels declined precipitously long before bleaching itself was evident, suggesting that loss of expression of symbiosis-supporting genes may be involved in triggering bleaching.
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Affiliation(s)
- Phillip A Cleves
- Department of Genetics, Stanford University School of Medicine, Stanford, CA 94305
| | - Cory J Krediet
- Department of Genetics, Stanford University School of Medicine, Stanford, CA 94305
- Department of Marine Science, Eckerd College, St. Petersburg, FL 33711
| | - Erik M Lehnert
- Department of Genetics, Stanford University School of Medicine, Stanford, CA 94305
| | - Masayuki Onishi
- Department of Genetics, Stanford University School of Medicine, Stanford, CA 94305
| | - John R Pringle
- Department of Genetics, Stanford University School of Medicine, Stanford, CA 94305;
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16
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Experimental investigation of tidal and freshwater influence on Symbiodiniaceae abundance in Anthopleura elegantissima. PLoS One 2020; 15:e0238361. [PMID: 32866211 PMCID: PMC7458305 DOI: 10.1371/journal.pone.0238361] [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: 09/10/2019] [Accepted: 08/15/2020] [Indexed: 11/19/2022] Open
Abstract
The San Francisco Bay outflow creates a tidally influenced low-salinity plume that affects adjacent coastal sites. In the study region, Anthopleura elegantissima (Cnidaria; Anthozoa) hosts a single symbiont, the dinoflagellate Breviolum muscatinei. Salinity, temperature, and aerial stress induce a bleaching response similar to corals where symbionts are expelled, causing further energetic stress. Using field observations of environmental conditions and symbiont abundance at sites on a gradient of exposure to estuarine outflow, along with a fully crossed multifactorial lab experiment, we tested for changes in symbiont abundance in response to various combinations of three stressors. Lab experiments were designed to mimic short term outflow events with low salinity, high temperature, and aerial exposure treatments. The lab aerial exposure treatment was a statistically significant factor in suppressing symbiont repopulation (ANOVA, p = .017). In the field, symbiont density decreased with increasing tidal height at the site closest to freshwater outflow (ANOVA, p = .007), suggesting that aerial exposure may affect symbiont density more than sea surface temperature and salinity. Unanticipated documentation of survival in 9 months of sand burial and subsequent repopulation of symbionts is reported as a six-month extension to past observations, exemplifying strong tolerance to environmental insult in this Cnidarian mutualism. The study of this symbiosis is useful in examining predicted changes in ocean conditions in tidepool communities and considering relative sources of stress.
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17
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Huffmyer AS, Matsuda SB, Eggers AR, Lemus JD, Gates RD. Evaluation of laser scanning confocal microscopy as a method for characterizing reef-building coral tissue thickness and Symbiodiniaceae fluorescence. J Exp Biol 2020; 223:jeb220335. [PMID: 32098888 DOI: 10.1242/jeb.220335] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2019] [Accepted: 02/13/2020] [Indexed: 08/26/2023]
Abstract
Predicting the sensitivity of reef-building corals to disturbance, including bleaching, requires an understanding of physiological responses to stressors, which may be limited by destructive sampling and the capacity of common methodologies to characterize early life history stages. We developed a new methodology using laser scanning confocal microscopy (LSCM) to measure and track the physiological condition of corals. In a thermal stress experiment, we used LSCM to track coral condition during bleaching in adults and juveniles of two species, Montipora capitata and Pocillopora acuta Depth of fluorescence in coral tissues provides a proxy measure of tissue thickness, whereas Symbiodiniaceae population fluorescence relates to both population density and chlorophyll a content. In response to thermal stress, there were significant shifts in tissue thickness and Symbiodiniaceae fluorescence with differences between life stages. This method is particularly well suited for detecting shifts in physiological condition of living corals in laboratory studies, especially in small juvenile colonies.
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Affiliation(s)
- A S Huffmyer
- Hawai'i Institute of Marine Biology, University of Hawai'i at Mānoa, 46-007 Lilipuna Road, Kāne'ohe, HI 96744, USA
| | - S B Matsuda
- Hawai'i Institute of Marine Biology, University of Hawai'i at Mānoa, 46-007 Lilipuna Road, Kāne'ohe, HI 96744, USA
| | - A R Eggers
- Department of Molecular and Cell Biology, University of California, Berkeley, 142 LSA #3200 Berkeley, CA 94720, USA
| | - J D Lemus
- Hawai'i Institute of Marine Biology, University of Hawai'i at Mānoa, 46-007 Lilipuna Road, Kāne'ohe, HI 96744, USA
| | - R D Gates
- Hawai'i Institute of Marine Biology, University of Hawai'i at Mānoa, 46-007 Lilipuna Road, Kāne'ohe, HI 96744, USA
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18
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Xiang T, Lehnert E, Jinkerson RE, Clowez S, Kim RG, DeNofrio JC, Pringle JR, Grossman AR. Symbiont population control by host-symbiont metabolic interaction in Symbiodiniaceae-cnidarian associations. Nat Commun 2020; 11:108. [PMID: 31913264 PMCID: PMC6949306 DOI: 10.1038/s41467-019-13963-z] [Citation(s) in RCA: 58] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2019] [Accepted: 12/11/2019] [Indexed: 01/28/2023] Open
Abstract
In cnidarian-Symbiodiniaceae symbioses, algal endosymbiont population control within the host is needed to sustain a symbiotic relationship. However, the molecular mechanisms that underlie such population control are unclear. Here we show that a cnidarian host uses nitrogen limitation as a primary mechanism to control endosymbiont populations. Nitrogen acquisition and assimilation transcripts become elevated in symbiotic Breviolum minutum algae as they reach high-densities within the sea anemone host Exaiptasia pallida. These same transcripts increase in free-living algae deprived of nitrogen. Symbiotic algae also have an elevated carbon-to-nitrogen ratio and shift metabolism towards scavenging nitrogen from purines relative to free-living algae. Exaiptasia glutamine synthetase and glutamate synthase transcripts concomitantly increase with the algal endosymbiont population, suggesting an increased ability of the host to assimilate ammonium. These results suggest algal growth and replication in hospite is controlled by access to nitrogen, which becomes limiting for the algae as their population within the host increases. The relationship between the coral animal and symbiotic algae is essential to coral health, and researchers are turning to Exaiptasia, a model cnidarian system, to study this relationship mechanistically. Here the authors find that endosymbiotic algae become limited by nitrogen at high population densities and provide the host with high levels of fixed carbon.
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Affiliation(s)
- Tingting Xiang
- Department of Plant Biology, Carnegie Institution for Science, Stanford, CA, 94305, USA. .,Department of Biological Sciences, University of North Carolina at Charlotte, Charlotte, NC, 28223, USA.
| | - Erik Lehnert
- Department of Genetics, Stanford University School of Medicine, Stanford, CA, 94305, USA
| | - Robert E Jinkerson
- Department of Chemical and Environmental Engineering, University of California, Riverside, CA, 92521, USA
| | - Sophie Clowez
- Department of Plant Biology, Carnegie Institution for Science, Stanford, CA, 94305, USA
| | - Rick G Kim
- Department of Plant Biology, Carnegie Institution for Science, Stanford, CA, 94305, USA
| | - Jan C DeNofrio
- Department of Genetics, Stanford University School of Medicine, Stanford, CA, 94305, USA
| | - John R Pringle
- Department of Genetics, Stanford University School of Medicine, Stanford, CA, 94305, USA
| | - Arthur R Grossman
- Department of Plant Biology, Carnegie Institution for Science, Stanford, CA, 94305, USA
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19
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Gegner HM, Rädecker N, Ochsenkühn M, Barreto MM, Ziegler M, Reichert J, Schubert P, Wilke T, Voolstra CR. High levels of floridoside at high salinity link osmoadaptation with bleaching susceptibility in the cnidarian-algal endosymbiosis. Biol Open 2019; 8:8/12/bio045591. [PMID: 31843766 PMCID: PMC6918757 DOI: 10.1242/bio.045591] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Coral reefs are in global decline mainly due to increasing sea surface temperatures triggering coral bleaching. Recently, high salinity has been linked to increased thermotolerance and decreased bleaching in the sea anemone coral model Aiptasia. However, the underlying processes remain elusive. Using two Aiptasia host–endosymbiont pairings, we induced bleaching at different salinities and show reduced reactive oxygen species (ROS) release at high salinities, suggesting a role of osmoadaptation in increased thermotolerance. A subsequent screening of osmolytes revealed that this effect was only observed in algal endosymbionts that produce 2-O-glycerol-α-D-galactopyranoside (floridoside), an osmolyte capable of scavenging ROS. This result argues for a mechanistic link between osmoadaptation and thermotolerance, mediated by ROS-scavenging osmolytes (e.g., floridoside). This sheds new light on the putative mechanisms underlying the remarkable thermotolerance of corals from water bodies with high salinity such as the Red Sea or Persian/Arabian Gulf and holds implications for coral thermotolerance under climate change. This article has an associated First Person interview with the first author of the paper. Summary: Using the coral model Aiptasia, we show increased thermotolerance at high salinities, concomitant with a reduced reactive oxygen species (ROS) release by algal endosymbionts. This suggests a mechanistic link between osmoadaptation and thermotolerance, mediated by ROS-scavenging osmolytes.
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Affiliation(s)
- Hagen M Gegner
- Red Sea Research Center, Division of Biological and Environmental Science and Engineering (BESE), King Abdullah University of Science and Technology (KAUST), Thuwal 23955, Saudi Arabia
| | - Nils Rädecker
- Red Sea Research Center, Division of Biological and Environmental Science and Engineering (BESE), King Abdullah University of Science and Technology (KAUST), Thuwal 23955, Saudi Arabia
| | - Michael Ochsenkühn
- Division of Science and Engineering, New York University Abu Dhabi (NYUAD), Saadiyat Island, Abu Dhabi, United Arab Emirates
| | - Marcelle M Barreto
- Red Sea Research Center, Division of Biological and Environmental Science and Engineering (BESE), King Abdullah University of Science and Technology (KAUST), Thuwal 23955, Saudi Arabia
| | - Maren Ziegler
- Red Sea Research Center, Division of Biological and Environmental Science and Engineering (BESE), King Abdullah University of Science and Technology (KAUST), Thuwal 23955, Saudi Arabia.,Department of Animal Ecology & Systematics, Justus Liebig University, 35390 Giessen, Germany
| | - Jessica Reichert
- Department of Animal Ecology & Systematics, Justus Liebig University, 35390 Giessen, Germany
| | - Patrick Schubert
- Department of Animal Ecology & Systematics, Justus Liebig University, 35390 Giessen, Germany
| | - Thomas Wilke
- Department of Animal Ecology & Systematics, Justus Liebig University, 35390 Giessen, Germany
| | - Christian R Voolstra
- Red Sea Research Center, Division of Biological and Environmental Science and Engineering (BESE), King Abdullah University of Science and Technology (KAUST), Thuwal 23955, Saudi Arabia .,Department of Biology, University of Konstanz, 78457 Konstanz, Germany
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20
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Xiao D, Ling KHJ, Tarnowski T, Majeed SR, Kearney B, Kolaris C, Zondlo S. The determination of human peripheral blood mononuclear cell counts using a genomic DNA standard and application in tenofovir diphosphate quantitation. Anal Biochem 2019; 585:113399. [PMID: 31437427 DOI: 10.1016/j.ab.2019.113399] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2019] [Revised: 08/13/2019] [Accepted: 08/14/2019] [Indexed: 10/26/2022]
Abstract
A fluorescent quantitation method to determine PBMC-derived DNA amounts using purified human genomic DNA (gDNA) as the reference standard was developed and validated. gDNA was measured in a fluorescence-based assay using a DNA intercalant, SYBR green. The fluorescence signal was proportional to the amount (mass) of DNA in the sample. The results confirmed a linear fit from 0.0665 to 1.17 μg/μL for gDNA, corresponding to 2.0 × 106 to 35.0 × 106 cells/PBMC sample. Intra-batch and inter-batch accuracy (%RE) was within ±15%, and precision (%CV) was <15%. Benchtop stability, freeze/thaw stability and long term storage stability of gDNA in QC sample matrix, PBMC pellets samples, and pellet debris samples, respectively, as well as dilution linearity had been established. Consistency between hemocytometry cell counting method and gDNA-based counting method was established. 6 out of 6 evaluated PBMC lots had hemocytometry cell counts that were within ±20% of the cell counts determined by the gDNA method. This method was used in conjunction with a validated LC-MS/MS method to determine the level of tenofovir diphosphate (TFV-DP), the active intracellular metabolite of the prodrugs tenofovir alafenamide (TAF) and tenofovir disoproxil fumarate (TDF), measured in PBMCs in clinical trials of TAF or TDF-containing fixed dose combinations.
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21
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Biomimetic dense lamellar scaffold based on a colloidal complex of the polyaniline (PANi) and biopolymers for electroactive and physiomechanical stimulation of the myocardial. Colloids Surf A Physicochem Eng Asp 2019. [DOI: 10.1016/j.colsurfa.2019.123650] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
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22
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Thomas L, López EH, Morikawa MK, Palumbi SR. Transcriptomic resilience, symbiont shuffling, and vulnerability to recurrent bleaching in reef‐building corals. Mol Ecol 2019; 28:3371-3382. [DOI: 10.1111/mec.15143] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2019] [Revised: 05/14/2019] [Accepted: 06/04/2019] [Indexed: 12/22/2022]
Affiliation(s)
- Luke Thomas
- Australian Institute of Marine Science, Indian Ocean Marine Research Centre Perth WA Australia
- Oceans Graduate School The UWA Oceans Institute, The University of Western Australia Perth WA Australia
- Biology Department, Hopkins Marine Station Stanford University Stanford CA USA
| | - Elora H. López
- Biology Department, Hopkins Marine Station Stanford University Stanford CA USA
| | - Megan K. Morikawa
- Biology Department, Hopkins Marine Station Stanford University Stanford CA USA
| | - Stephen R. Palumbi
- Biology Department, Hopkins Marine Station Stanford University Stanford CA USA
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23
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Vembadi A, Menachery A, Qasaimeh MA. Cell Cytometry: Review and Perspective on Biotechnological Advances. Front Bioeng Biotechnol 2019; 7:147. [PMID: 31275933 PMCID: PMC6591278 DOI: 10.3389/fbioe.2019.00147] [Citation(s) in RCA: 70] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2019] [Accepted: 05/31/2019] [Indexed: 12/20/2022] Open
Abstract
Cell identification and enumeration are essential procedures within clinical and research laboratories. For over 150 years, quantitative investigation of body fluids such as counts of various blood cells has been an important tool for diagnostic analysis. With the current evolution of point-of-care diagnostics and precision medicine, cheap and precise cell counting technologies are in demand. This article reviews the timeline and recent notable advancements in cell counting that have occurred as a result of improvements in sensing including optical and electrical technology, enhancements in image processing capabilities, and contributions of micro and nanotechnologies. Cell enumeration methods have evolved from the use of manual counting using a hemocytometer to automated cell counters capable of providing reliable counts with high precision and throughput. These developments have been enabled by the use of precision engineering, micro and nanotechnology approaches, automation and multivariate data analysis. Commercially available automated cell counters can be broadly classified into three categories based on the principle of detection namely, electrical impedance, optical analysis and image analysis. These technologies have many common scientific uses, such as hematological analysis, urine analysis and bacterial enumeration. In addition to commercially available technologies, future technological trends using lab-on-a-chip devices have been discussed in detail. Lab-on-a-chip platforms utilize the existing three detection technologies with innovative design changes utilizing advanced nano/microfabrication to produce customized devices suited to specific applications.
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Affiliation(s)
- Abhishek Vembadi
- Division of Engineering, New York University, Abu Dhabi, United Arab Emirates
| | - Anoop Menachery
- Division of Engineering, New York University, Abu Dhabi, United Arab Emirates
| | - Mohammad A. Qasaimeh
- Division of Engineering, New York University, Abu Dhabi, United Arab Emirates
- Department of Mechanical and Aerospace Engineering, New York University Tandon School of Engineering, Brooklyn, NY, United States
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24
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卢 余, 钟 春, 贾 力, 陈 建. 基于荧光染料的珊瑚共生菌的群落组成及表型检测. Bio Protoc 2019. [DOI: 10.21769/bioprotoc.1010347] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022] Open
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25
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Okubo N, Takahashi S, Nakano Y. Microplastics disturb the anthozoan-algae symbiotic relationship. MARINE POLLUTION BULLETIN 2018; 135:83-89. [PMID: 30301104 DOI: 10.1016/j.marpolbul.2018.07.016] [Citation(s) in RCA: 52] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/12/2018] [Revised: 07/02/2018] [Accepted: 07/03/2018] [Indexed: 06/08/2023]
Abstract
World production of plastic has dramatically increased from the 1950's and now it reaches approximately 311 million tons per year. The resulting accumulation of small plastic detritus less than 5 mm in size, termed "microplastics", has started threatening the life cycles of marine organisms. Here we show the first evidence that microplastics disturb the initiation of symbiotic relationships in anthozoan-algae symbiosis. We found in both the aposymbiotic sea-anemone Aiptasia sp. and the coral Favites chinensis that the infectivity of symbiotic algae into the host is severely suppressed by microspheres fed either directly or indirectly through microsphere-fed Artemia sp. Similar trends were seen when microplastics collected from commercial facewash were used instead of microspheres. Therefore, ongoing accumulation of microplastics in the ocean might disturb the healthy anthozoan-algae symbiotic relationships, which are cornerstones of the biologically enriched coral reef ecosystem.
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Affiliation(s)
- Nami Okubo
- Department of Economics, Tokyo Keizai University, 1-7-34 Minamimachi, Kokubunji, Tokyo 185-8502, Japan.
| | - Shunichi Takahashi
- Division of Environmental Photobiology, National Institute for Basic Biology, Nishigonaka 38, Myodaiji, Okazaki 444-8585, Japan
| | - Yoshikatsu Nakano
- Tropical Biosphere Research Center, Sesoko Station, Ryukyu University, Motobu, Okinawa 905-0227, Japan
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26
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Thomas L, Palumbi SR. The genomics of recovery from coral bleaching. Proc Biol Sci 2018; 284:rspb.2017.1790. [PMID: 29070726 DOI: 10.1098/rspb.2017.1790] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2017] [Accepted: 09/22/2017] [Indexed: 12/12/2022] Open
Abstract
Ecological damage from periodic environmental extremes is often repaired in resilient ecosystems, but the rate of return to a non-damaged state is critical. Measures of recovery of communities include biomass, productivity and diversity, while measures of recovery of individuals tend to focus on physiological conditions and the return to normal metabolic functioning. Transcriptomics offers a window into the entire physiology of the organism under stress and can represent a holistic view of organismal recovery. In this study, we track the recovery of seven colonies of Acropora hyacinthus following a natural bleaching event. We identified a large environmental stress response in the field that involved approximately 20% of the host transcriptome. The transcriptome remained largely perturbed for at least six months after temperatures had cooled and four months after symbiont populations had recovered. Moreover, a small set of genes did not recover to previous expression levels even 12 months after the event, about the time that normal growth rates resumed. This study is among the first to incorporate transcriptomics into a longitudinal dataset of recovery from environmental stress. The data demonstrate large and lasting effects on coral physiology long after environmental conditions return to normal and symbiont populations recover.
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Affiliation(s)
- Luke Thomas
- Department of Biology, Hopkins Marine Station, Stanford University, Pacific Grove, CA 93950, USA
| | - Stephen R Palumbi
- Department of Biology, Hopkins Marine Station, Stanford University, Pacific Grove, CA 93950, USA
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27
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Rodriguez IB, Ho TY. Trace Metal Requirements and Interactions in Symbiodinium kawagutii. Front Microbiol 2018; 9:142. [PMID: 29467748 PMCID: PMC5808119 DOI: 10.3389/fmicb.2018.00142] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2017] [Accepted: 01/22/2018] [Indexed: 11/13/2022] Open
Abstract
Photosynthetic organisms need trace metals for various biological processes and different groups of microalgae have distinctive obligate necessities due to their respective biochemical requirements and ecological niches. We have previously shown that the dinoflagellate Symbiodinium kawagutii requires high concentrations of bioavailable Fe to achieve optimum growth. Here, we further explored the trace metal requirements of S. kawagutii with intensive focus on the effect of individual metal and its interaction with other divalent metals. We found that low Zn availability significantly decreases growth rates and results in elevated intracellular Mn, Co, Ni, and Fe quotas in the dinoflagellate. The results highlight the complex interaction among trace metals in S. kawagutii and suggest either metal replacement strategy to counter low Zn availability or enhanced uptake of other metals by non-specific divalent metal transporters. In this work, we also examined the Fe requirement of S. kawagutii using continuous cultures. We validated that 500 pM of Fe′ was sufficient to support maximum cell density during steady state growth period either at 26 or 28°C. This study shows that growth of S. kawagutii was limited by metal availability in the following order, Fe > Zn > Mn > Cu > Ni > Co. The fundamental information obtained for the free-living Symbiodinium shall provide insights into how trace metal availability, either from ambient seawater or hosts, affects growth and proliferation of symbiotic dinoflagellates and the interaction between symbiont and their hosts.
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Affiliation(s)
- Irene B Rodriguez
- Research Center for Environmental Changes, Academia Sinica, Taipei, Taiwan
| | - Tung-Yuan Ho
- Research Center for Environmental Changes, Academia Sinica, Taipei, Taiwan.,Institute of Oceanography, National Taiwan University, Taipei, Taiwan
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Xiang T, Jinkerson RE, Clowez S, Tran C, Krediet CJ, Onishi M, Cleves PA, Pringle JR, Grossman AR. Glucose-Induced Trophic Shift in an Endosymbiont Dinoflagellate with Physiological and Molecular Consequences. PLANT PHYSIOLOGY 2018; 176:1793-1807. [PMID: 29217594 PMCID: PMC5813547 DOI: 10.1104/pp.17.01572] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/02/2017] [Accepted: 12/04/2017] [Indexed: 05/12/2023]
Abstract
Interactions between the dinoflagellate endosymbiont Symbiodinium and its cnidarian hosts (e.g. corals, sea anemones) are the foundation of coral-reef ecosystems. Carbon flow between the partners is a hallmark of this mutualism, but the mechanisms governing this flow and its impact on symbiosis remain poorly understood. We showed previously that although Symbiodinium strain SSB01 can grow photoautotrophically, it can grow mixotrophically or heterotrophically when supplied with Glc, a metabolite normally transferred from the alga to its host. Here we show that Glc supplementation of SSB01 cultures causes a loss of pigmentation and photosynthetic activity, disorganization of thylakoid membranes, accumulation of lipid bodies, and alterations of cell-surface morphology. We used global transcriptome analyses to determine if these physiological changes were correlated with changes in gene expression. Glc-supplemented cells exhibited a marked reduction in levels of plastid transcripts encoding photosynthetic proteins, although most nuclear-encoded transcripts (including those for proteins involved in lipid synthesis and formation of the extracellular matrix) exhibited little change in their abundances. However, the altered carbon metabolism in Glc-supplemented cells was correlated with modest alterations (approximately 2x) in the levels of some nuclear-encoded transcripts for sugar transporters. Finally, Glc-bleached SSB01 cells appeared unable to efficiently populate anemone larvae. Together, these results suggest links between energy metabolism and cellular physiology, morphology, and symbiotic interactions. However, the results also show that in contrast to many other organisms, Symbiodinium can undergo dramatic physiological changes that are not reflected by major changes in the abundances of nuclear-encoded transcripts and thus presumably reflect posttranscriptional regulatory processes.
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Affiliation(s)
- Tingting Xiang
- Carnegie Institution for Science, Department of Plant Biology, Stanford, California 94305
| | - Robert E Jinkerson
- Carnegie Institution for Science, Department of Plant Biology, Stanford, California 94305
- Department of Chemical and Environmental Engineering, University of California, Riverside, California 92521
| | - Sophie Clowez
- Carnegie Institution for Science, Department of Plant Biology, Stanford, California 94305
| | - Cawa Tran
- Department of Genetics, Stanford University School of Medicine, Stanford, California 94305
- Department of Biological Sciences, California State University, Chico, California 95929
| | - Cory J Krediet
- Department of Genetics, Stanford University School of Medicine, Stanford, California 94305
- Eckerd College, Department of Marine Science, St. Petersburg, Florida 33711
| | - Masayuki Onishi
- Department of Genetics, Stanford University School of Medicine, Stanford, California 94305
| | - Phillip A Cleves
- Department of Genetics, Stanford University School of Medicine, Stanford, California 94305
| | - John R Pringle
- Department of Genetics, Stanford University School of Medicine, Stanford, California 94305
| | - Arthur R Grossman
- Carnegie Institution for Science, Department of Plant Biology, Stanford, California 94305
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Gegner HM, Ziegler M, Rädecker N, Buitrago-López C, Aranda M, Voolstra CR. High salinity conveys thermotolerance in the coral model Aiptasia. Biol Open 2017; 6:1943-1948. [PMID: 29175860 PMCID: PMC5769654 DOI: 10.1242/bio.028878] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
The endosymbiosis between dinoflagellate algae of the genus Symbiodinium and stony corals provides the foundation of coral reef ecosystems. Coral bleaching, the expulsion of endosymbionts from the coral host tissue as a consequence of heat or light stress, poses a threat to reef ecosystem functioning on a global scale. Hence, a better understanding of the factors contributing to heat stress susceptibility and tolerance is needed. In this regard, some of the most thermotolerant corals live in particularly saline habitats, but possible effects of high salinity on thermotolerance in corals are anecdotal. Here we test the hypothesis that high salinity may lead to increased thermotolerance. We conducted a heat stress experiment at low, intermediate, and high salinities using a set of host-endosymbiont combinations of the coral model Aiptasia. As expected, all host-endosymbiont combinations showed reduced photosynthetic efficiency and endosymbiont loss during heat stress, but the severity of bleaching was significantly reduced with increasing salinities for one of the host-endosymbiont combinations. Our results show that higher salinities can convey increased thermotolerance in Aiptasia, although this effect seems to be dependent on the particular host strain and/or associated symbiont type. This finding may help explain the extraordinarily high thermotolerance of corals in high salinity environments, such as the Red Sea and the Persian/Arabian Gulf, and provides novel insight regarding factors that contribute to thermotolerance. Since our results are based on a salinity effect in symbiotic sea anemones, it remains to be determined whether this salinity effect can also be observed in stony corals. Summary: High salinity can be a factor contributing to increased cnidarian thermal tolerance, as indicated by reduced algal endosymbiont loss and reduced photosynthetic impairment in the sea anemone Aiptasia.
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Affiliation(s)
- Hagen M Gegner
- Red Sea Research Center, Division of Biological and Environmental Science and Engineering (BESE), King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Saudi Arabia
| | - Maren Ziegler
- Red Sea Research Center, Division of Biological and Environmental Science and Engineering (BESE), King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Saudi Arabia
| | - Nils Rädecker
- Red Sea Research Center, Division of Biological and Environmental Science and Engineering (BESE), King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Saudi Arabia
| | - Carol Buitrago-López
- Red Sea Research Center, Division of Biological and Environmental Science and Engineering (BESE), King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Saudi Arabia
| | - Manuel Aranda
- Red Sea Research Center, Division of Biological and Environmental Science and Engineering (BESE), King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Saudi Arabia
| | - Christian R Voolstra
- Red Sea Research Center, Division of Biological and Environmental Science and Engineering (BESE), King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Saudi Arabia
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Bellis ES, Denver DR. Natural Variation in Responses to Acute Heat and Cold Stress in a Sea Anemone Model System for Coral Bleaching. THE BIOLOGICAL BULLETIN 2017; 233:168-181. [PMID: 29373064 DOI: 10.1086/694890] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Rising ocean temperatures disrupt the symbiosis between corals and their microalgae, accelerating global decline of coral reef ecosystems. Because of the difficulty of performing laboratory experiments with corals, the sea anemone Aiptasia has emerged as an important model system for molecular studies of coral bleaching and symbiosis. Here, we investigate natural variation in bleaching responses among different genetic lineages of Aiptasia. Both heat- and cold-induced paths to symbiosis breakdown were analyzed. Significant genetic variation in response to acute heat stress was observed, with severe bleaching of two Aiptasia strains from Hawaii but minimal bleaching of strains from the U.S. South Atlantic, including the strain used to generate the Aiptasia reference genome. Both strains from Hawaii hosted Symbiodinium type B1, whereas strains from the U.S. South Atlantic hosted type A4 or B2. In contrast to the results from exposures to acute heat stress, negligible variation was observed in response to a pulsed cold shock despite moderate bleaching across all strains. These results support our hypothesis that bleaching responses to distinct stressors are independent. Our findings emphasize the role of stress regime when predicting adaptive responses of symbiotic cnidarians to changing climates, because genetic variation may exist for some forms of stress-induced bleaching but not others.
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Rosental B, Kozhekbaeva Z, Fernhoff N, Tsai JM, Traylor-Knowles N. Coral cell separation and isolation by fluorescence-activated cell sorting (FACS). BMC Cell Biol 2017; 18:30. [PMID: 28851289 PMCID: PMC5575905 DOI: 10.1186/s12860-017-0146-8] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2016] [Accepted: 08/20/2017] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Generalized methods for understanding the cell biology of non-model species are quite rare, yet very much needed. In order to address this issue, we have modified a technique traditionally used in the biomedical field for ecological and evolutionary research. Fluorescent activated cell sorting (FACS) is often used for sorting and identifying cell populations. In this study, we developed a method to identify and isolate different cell populations in corals and other cnidarians. METHODS Using fluorescence-activated cell sorting (FACS), coral cell suspension were sorted into different cellular populations using fluorescent cell markers that are non-species specific. Over 30 different cell markers were tested. Additionally, cell suspension from Aiptasia pallida was also tested, and a phagocytosis test was done as a downstream functional assay. RESULTS We found that 24 of the screened markers positively labeled coral cells and 16 differentiated cell sub-populations. We identified 12 different cellular sub-populations using three markers, and found that each sub-population is primarily homogeneous. Lastly, we verified this technique in a sea anemone, Aiptasia pallida, and found that with minor modifications, a similar gating strategy can be successfully applied. Additionally, within A. pallida, we show elevated phagocytosis of sorted cells based on an immune associated marker. CONCLUSIONS In this study, we successfully adapted FACS for isolating coral cell populations and conclude that this technique is translatable for future use in other species. This technique has the potential to be used for different types of studies on the cellular stress response and other immunological studies.
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Affiliation(s)
- Benyamin Rosental
- Institute for Stem Cell Biology and Regenerative Medicine, Stanford University School of Medicine, Stanford, CA, 94305, USA.
- Department of Pathology, Hopkins Marine Station, Stanford University, 120 Ocean View Blvd, Pacific Grove, CA, 93950, USA.
| | - Zhanna Kozhekbaeva
- University of Miami, Rosenstiel School of Marine and Atmospheric Science, 4600 Rickenbacker Causeway, Florida, 33149, USA
| | - Nathaniel Fernhoff
- Institute for Stem Cell Biology and Regenerative Medicine, Stanford University School of Medicine, Stanford, CA, 94305, USA
| | - Jonathan M Tsai
- Institute for Stem Cell Biology and Regenerative Medicine, Stanford University School of Medicine, Stanford, CA, 94305, USA
| | - Nikki Traylor-Knowles
- University of Miami, Rosenstiel School of Marine and Atmospheric Science, 4600 Rickenbacker Causeway, Florida, 33149, USA.
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32
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Bieri T, Onishi M, Xiang T, Grossman AR, Pringle JR. Relative Contributions of Various Cellular Mechanisms to Loss of Algae during Cnidarian Bleaching. PLoS One 2016; 11:e0152693. [PMID: 27119147 PMCID: PMC4847765 DOI: 10.1371/journal.pone.0152693] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2015] [Accepted: 03/17/2016] [Indexed: 12/15/2022] Open
Abstract
When exposed to stress such as high seawater temperature, corals and other cnidarians can bleach due to loss of symbiotic algae from the host tissue and/or loss of pigments from the algae. Although the environmental conditions that trigger bleaching are reasonably well known, its cellular and molecular mechanisms are not well understood. Previous studies have reported the occurrence of at least four different cellular mechanisms for the loss of symbiotic algae from the host tissue: in situ degradation of algae, exocytic release of algae from the host, detachment of host cells containing algae, and death of host cells containing algae. The relative contributions of these several mechanisms to bleaching remain unclear, and it is also not known whether these relative contributions change in animals subjected to different types and/or durations of stresses. In this study, we used a clonal population of the small sea anemone Aiptasia, exposed individuals to various precisely controlled stress conditions, and quantitatively assessed the several possible bleaching mechanisms in parallel. Under all stress conditions tested, except for acute cold shock at 4°C, expulsion of intact algae from the host cells appeared to be by far the predominant mechanism of bleaching. During acute cold shock, in situ degradation of algae and host-cell detachment also became quantitatively significant, and the algae released under these conditions appeared to be severely damaged.
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Affiliation(s)
- Tamaki Bieri
- Department of Genetics, Stanford University School of Medicine, Stanford, California, United States of America
- Department of Biology, Stanford University, Stanford, California, United States of America
| | - Masayuki Onishi
- Department of Genetics, Stanford University School of Medicine, Stanford, California, United States of America
| | - Tingting Xiang
- Department of Plant Biology, Carnegie Institution for Science, Stanford, California, United States of America
| | - Arthur R. Grossman
- Department of Biology, Stanford University, Stanford, California, United States of America
- Department of Plant Biology, Carnegie Institution for Science, Stanford, California, United States of America
| | - John R Pringle
- Department of Genetics, Stanford University School of Medicine, Stanford, California, United States of America
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