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Cao L, Bi D, Fan W, Xu J, Beardall J, Gao K, Wu Y. Warming exacerbates the impacts of ultraviolet radiation in temperate diatoms but alleviates the effect on polar species. Photochem Photobiol 2024; 100:491-498. [PMID: 37528525 DOI: 10.1111/php.13844] [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] [Revised: 07/20/2023] [Accepted: 07/23/2023] [Indexed: 08/03/2023]
Abstract
Under global change scenarios, the sea surface temperature is increasing steadily along with other changes to oceanic environments. Consequently, marine diatoms are influenced by multiple ocean global change drivers. We hypothesized that temperature rise mediates the responses of polar and temperate diatoms to UV radiation (UVR) to different extents, and exposed the temperate centric diatoms, Thalassiosira weissflogii and Skeletonema costatum, and a polar pennate diatom Entomoneis sp., to warming (+5°C) for 10 days, then performed short-term incubations under different radiation treatments with or without UVR. The effective quantum yields of the three diatoms were stable during exposure to PAR, but decreased when exposed to PAR + UVR, leading to significant UV-induced inhibition, which was 3% and 9%, respectively, for T. weissflogii and S. costatum under ambient temperature but increased to 12% and 17%, respectively, in the cells acclimated to the warming treatment. In contrast, UVR induced much higher inhibition, by about 45%, in the polar diatom Entomoneis sp. at ambient temperature, and the warming treatment alleviated the UV-induced inhibition, which dropped to 36%. The growth rates were significantly inhibited by UVR in S. costatum under the warming treatment and in Entomoneis sp. under ambient temperature, while there was no significant effect for T. weissflogii. Our results indicate that the polar diatom was more sensitive to UVR though warming could alleviate its impact, whereas the temperate diatoms were less sensitive to UVR but warming exacerbated its impacts, implying that diatoms living in different regions may exhibit differential responses to global changes.
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Affiliation(s)
- Lixin Cao
- Jiangsu Key Laboratory of Marine Bioresources and Environment/Co-Innovation Center of Jiangsu Marine Bio-Industry Technology, Jiangsu Ocean University, Lianyungang, China
| | - Dongquan Bi
- Jiangsu Key Laboratory of Marine Bioresources and Environment/Co-Innovation Center of Jiangsu Marine Bio-Industry Technology, Jiangsu Ocean University, Lianyungang, China
| | - Wei Fan
- Jiangsu Key Laboratory of Marine Bioresources and Environment/Co-Innovation Center of Jiangsu Marine Bio-Industry Technology, Jiangsu Ocean University, Lianyungang, China
| | - Juntian Xu
- Jiangsu Key Laboratory of Marine Bioresources and Environment/Co-Innovation Center of Jiangsu Marine Bio-Industry Technology, Jiangsu Ocean University, Lianyungang, China
- Key Laboratory of Coastal Salt Marsh Ecosystems and Resources Ministry of Natural Resources, Jiangsu Ocean University, Lianyungang, China
| | - John Beardall
- State Key Laboratory of Marine Environmental Science, College of Ocean & Earth Sciences, Xiamen University, Xiamen, China
- School of Biological Sciences, Monash University, Clayton, Victoria, Australia
| | - Kunshan Gao
- State Key Laboratory of Marine Environmental Science, College of Ocean & Earth Sciences, Xiamen University, Xiamen, China
| | - Yaping Wu
- Jiangsu Key Laboratory of Marine Bioresources and Environment/Co-Innovation Center of Jiangsu Marine Bio-Industry Technology, Jiangsu Ocean University, Lianyungang, China
- Key Laboratory of Coastal Salt Marsh Ecosystems and Resources Ministry of Natural Resources, Jiangsu Ocean University, Lianyungang, China
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2
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Jiang X, Zhang Y, Hutchins DA, Gao K. Nitrogen-limitation exacerbates the impact of ultraviolet radiation on the coccolithophore Gephyrocapsa oceanica. JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY. B, BIOLOGY 2022; 226:112368. [PMID: 34864530 DOI: 10.1016/j.jphotobiol.2021.112368] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/16/2021] [Revised: 11/16/2021] [Accepted: 11/20/2021] [Indexed: 12/13/2022]
Abstract
To investigate effects of UV radiation (UVR, 280-400 nm) on coccolithophorids under nutrient-limited conditions, we grew Gephyrocapsa oceanica to determine its resilience to consecutive daily short-term exposures to +UVR (irradiances >295 nm) under a range of nitrate availabilities (100, 24, 12, 6 and 3 μM). +UVR alone significantly hampered the growth of G. oceanica, with the synergistic negative effects of +UVR and N-limitation being about 58% and 22% greater than under UVR or N-limitation alone, respectively. Most 3 μM nitrate cultures died, but those exposed to UVR succumbed sooner. This was due to a failure of photoprotection and repair mechanisms under low N-availability with exposures to UVR. Additionally, the UVR-induced inhibition of the effective quantum yield of photosystem II (PSII) was significantly higher and was further aggravated by N limitation. The algal cells increased photoprotective pigments and UV-absorbing compounds as a priority rather than using calcification for defense against UVR, indicating a trade-off in energy and resource allocation. Our results indicate the negative effects of UVR on coccolithophorid growth and photosynthesis, and highlight the important role of N availability in defense against UVR as well as high PAR. We predict that enhanced N-limitation in future surface oceans due to warming-induced stratification will exacerbate the sensitivity of G. oceanica to UVR, while coccolithophores can be potentially more susceptible to other environmental stresses due to increased levels of nutrient limitation.
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Affiliation(s)
- Xiaowen Jiang
- State Key Laboratory of Marine Environmental Science & College of Ocean and Earth Sciences, Xiamen University, Xiamen, China
| | - Yong Zhang
- State Key Laboratory of Marine Environmental Science & College of Ocean and Earth Sciences, Xiamen University, Xiamen, China; College of Environmental Science and Engineering and Fujian Key Laboratory of Pollution Control and Resource Recycling, Fujian Normal University, Fuzhou, China
| | - David A Hutchins
- Marine and Environmental Biology, University of Southern California, Los Angeles, CA, United States
| | - Kunshan Gao
- State Key Laboratory of Marine Environmental Science & College of Ocean and Earth Sciences, Xiamen University, Xiamen, China; Co-Innovation Center of Jiangsu Marine Bio-industry Technology, Jiangsu Ocean University, Lianyungang 222005, China.
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Jakubowski HV, Bock N, Busta L, Pearce M, Roston RL, Shomo ZD, Terrell CR. Introducing climate change into the biochemistry and molecular biology curriculum. BIOCHEMISTRY AND MOLECULAR BIOLOGY EDUCATION : A BIMONTHLY PUBLICATION OF THE INTERNATIONAL UNION OF BIOCHEMISTRY AND MOLECULAR BIOLOGY 2021; 49:167-188. [PMID: 32833339 DOI: 10.1002/bmb.21422] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/27/2020] [Revised: 07/09/2020] [Accepted: 07/13/2020] [Indexed: 06/11/2023]
Abstract
Our climate is changing due to anthropogenic emissions of greenhouse gases from the production and use of fossil fuels. Present atmospheric levels of CO2 were last seen 3 million years ago, when planetary temperature sustained high Arctic camels. As scientists and educators, we should feel a professional responsibility to discuss major scientific issues like climate change, and its profound consequences for humanity, with students who look up to us for knowledge and leadership, and who will be most affected in the future. We offer simple to complex backgrounds and examples to enable and encourage biochemistry educators to routinely incorporate this most important topic into their classrooms.
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Affiliation(s)
- Henry V Jakubowski
- Department of Chemistry, College of St. Benedict/St. John's University, St. Joseph, Minnesota, USA
| | - Nicholas Bock
- Lamont-Doherty Earth Observatory, Biology and Paleo Environment, Columbia University, Palisades, New York, USA
| | - Lucas Busta
- Department of Biochemistry and Center for Plant Science Innovation, University of Nebraska-Lincoln, Lincoln, Nebraska, USA
| | - Matthew Pearce
- NASA Goddard Space Flight Center, Office of Education, NASA Goddard Institute for Space Studies, New York, New York, USA
| | - Rebecca L Roston
- Department of Biochemistry and Center for Plant Science Innovation, University of Nebraska-Lincoln, Lincoln, Nebraska, USA
| | - Zachery D Shomo
- Department of Biochemistry and Center for Plant Science Innovation, University of Nebraska-Lincoln, Lincoln, Nebraska, USA
| | - Cassidy R Terrell
- Center for Learning Innovation, University of Minnesota Rochester, Rochester, Minnesota, USA
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Mann M, Serif M, Wrobel T, Eisenhut M, Madhuri S, Flachbart S, Weber APM, Lepetit B, Wilhelm C, Kroth PG. The Aureochrome Photoreceptor PtAUREO1a Is a Highly Effective Blue Light Switch in Diatoms. iScience 2020; 23:101730. [PMID: 33235981 PMCID: PMC7670200 DOI: 10.1016/j.isci.2020.101730] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2020] [Revised: 09/30/2020] [Accepted: 10/21/2020] [Indexed: 02/08/2023] Open
Abstract
Aureochromes represent a unique type of blue light photoreceptors that possess a blue light sensing flavin-binding LOV-domain and a DNA-binding bZIP domain, thus being light-driven transcription factors. The diatom Phaeodactylum tricornutum, a member of the essential marine primary producers, possesses four aureochromes (PtAUREO1a, 1b, 1c, 2). Here we show a dramatic change in the global gene expression pattern of P. tricornutum wild-type cells after a shift from red to blue light. About 75% of the genes show significantly changed transcript levels already after 10 and 60 min of blue light exposure, which includes genes of major transcription factors as well as other photoreceptors. Very surprisingly, this light-induced regulation of gene expression is almost completely inhibited in independent PtAureo1a knockout lines. Such a massive and fast transcriptional change depending on one single photoreceptor is so far unprecedented. We conclude that PtAUREO1a plays a key role in diatoms upon blue light exposure. Blue light induces a very fast transcriptional response in the diatom P. tricornutum This strong response is almost completely inhibited when Aureochrome 1a is absent The results imply a key role of PtAureo1a in blue light-induced responses in diatoms
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Affiliation(s)
- Marcus Mann
- Institut für Biologie, Universität Leipzig, 04009 Leipzig, Germany
| | - Manuel Serif
- Fachbereich Biologie, Universität Konstanz, 78457 Konstanz, Germany
| | - Thomas Wrobel
- Institut für Biochemie der Pflanzen, Cluster of Excellence on Plant Science (CEPLAS), Heinrich-Heine-Universität, 40225 Düsseldorf, Germany
| | - Marion Eisenhut
- Institut für Biochemie der Pflanzen, Cluster of Excellence on Plant Science (CEPLAS), Heinrich-Heine-Universität, 40225 Düsseldorf, Germany
| | - Shvaita Madhuri
- Fachbereich Biologie, Universität Konstanz, 78457 Konstanz, Germany
| | - Samantha Flachbart
- Institut für Biochemie der Pflanzen, Cluster of Excellence on Plant Science (CEPLAS), Heinrich-Heine-Universität, 40225 Düsseldorf, Germany
| | - Andreas P M Weber
- Institut für Biochemie der Pflanzen, Cluster of Excellence on Plant Science (CEPLAS), Heinrich-Heine-Universität, 40225 Düsseldorf, Germany
| | - Bernard Lepetit
- Fachbereich Biologie, Universität Konstanz, 78457 Konstanz, Germany
| | | | - Peter G Kroth
- Fachbereich Biologie, Universität Konstanz, 78457 Konstanz, Germany
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Multiple interacting environmental drivers reduce the impact of solar UVR on primary productivity in Mediterranean lakes. Sci Rep 2020; 10:19812. [PMID: 33188224 PMCID: PMC7666193 DOI: 10.1038/s41598-020-76237-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2020] [Accepted: 10/23/2020] [Indexed: 11/25/2022] Open
Abstract
Increases in rainfall, continental runoff, and atmospheric dust deposition are reducing water transparency in lakes worldwide (i.e. higher attenuation Kd). Also, ongoing alterations in multiple environmental drivers due to global change are unpredictably impacting phytoplankton responses and lakes functioning. Although both issues demand urgent research, it remains untested how the interplay between Kd and multiple interacting drivers affect primary productivity (Pc). We manipulated four environmental drivers in an in situ experiment—quality of solar ultraviolet radiation (UVR), nutrient concentration (Nut), CO2 partial pressure (CO2), and light regime (Mix)—to determine how the Pc of nine freshwater phytoplankton communities, found along a Kd gradient in Mediterranean ecosystems, changed as the number of interacting drivers increased. Our findings indicated that UVR was the dominant driver, its effect being between 3–60 times stronger, on average, than that of any other driver tested. Also, UVR had the largest difference in driver magnitude of all the treatments tested. A future UVR × CO2 × Mix × Nut scenario exerted a more inhibitory effect on Pc as the water column became darker. However, the magnitude of this synergistic effect was 40–60% lower than that exerted by double and triple interactions and by UVR acting independently. These results illustrate that although future global-change conditions could reduce Pc in Mediterranean lakes, multiple interacting drivers can temper the impact of a severely detrimental driver (i.e. UVR), particularly as the water column darkens.
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Li W, Wang T, Campbell DA, Gao K. Ocean acidification interacts with variable light to decrease growth but increase particulate organic nitrogen production in a diatom. MARINE ENVIRONMENTAL RESEARCH 2020; 160:104965. [PMID: 32291249 DOI: 10.1016/j.marenvres.2020.104965] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/12/2019] [Revised: 03/06/2020] [Accepted: 03/21/2020] [Indexed: 06/11/2023]
Abstract
Phytoplankton in the upper oceans are exposed to changing light levels due to mixing, diurnal solar cycles and weather conditions. Consequently, effects of ocean acidification are superimposed upon responses to variable light levels. We therefore grew a model diatom Thalassiosira pseudonana under either constant or variable light but at the same daily photon dose, with current low (400 μatm, LC) and future high CO2 (1000 μatm, HC) treatments. Variable light, compared with the constant light regime, decreased the growth rate, Chl a, Chl c, and carotenoid contents under both LC and HC conditions. Cells grown under variable light appeared more tolerant of high light as indicated by higher maximum relative electron transport rate and saturation light. Light variation interacted with high CO2/lowered pH to decrease the carbon fixation rate, but increased particulate organic carbon (POC) and particularly nitrogen (PON) per cell, which drove a decrease in C/N ratio, reflecting changes in the efficiency of energy transfer from photo-chemistry to net biomass production. Our results imply that elevated pCO2 under varying light conditions can lead to less primary productivity but more PON per biomass of the diatom, which might improve the food quality of diatoms and thereby influence biogeochemical nitrogen cycles.
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Affiliation(s)
- Wei Li
- State Key Laboratory of Marine Environmental Science & College of Ocean and Earth Sciences, Xiamen University, Xiamen, 361005, China; College of Life and Environmental Sciences, Huangshan University, Huangshan, 245041, China
| | - Tifeng Wang
- State Key Laboratory of Marine Environmental Science & College of Ocean and Earth Sciences, Xiamen University, Xiamen, 361005, China
| | - Douglas A Campbell
- Biology Department, Mount Allison University, Sackville, NB, E4L 1G7, Canada
| | - Kunshan Gao
- State Key Laboratory of Marine Environmental Science & College of Ocean and Earth Sciences, Xiamen University, Xiamen, 361005, China.
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7
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Lorenzo MR, Neale PJ, Sobrino C, León P, Vázquez V, Bresnan E, Segovia M. Effects of elevated CO 2 on growth, calcification, and spectral dependence of photoinhibition in the coccolithophore Emiliania huxleyi (Prymnesiophyceae) 1. JOURNAL OF PHYCOLOGY 2019; 55:775-788. [PMID: 31090939 DOI: 10.1111/jpy.12885] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/03/2019] [Accepted: 05/03/2019] [Indexed: 05/20/2023]
Abstract
We studied the effects of elevated CO2 concentrations on cell growth, calcification, and spectral variation in the sensitivity of photosynthesis to inhibition by solar radiation in the globally important coccolithophore Emiliania huxleyi. Growth rates and chlorophyll a content per cell showed no significant differences between elevated (800 ppmv) and ambient (400 ppmv) CO2 conditions. However, the production of organic carbon and the cell quotas for both carbon and nitrogen, increased under elevated CO2 conditions, whilst particulate inorganic carbon production rates decreased under the same conditions. Biometric analyses of cells showed that coccoliths only presented significant differences due to treatments in the central area width. Most importantly, the size of the coccosphere decreased under elevated CO2 conditions. The susceptibility of photosynthesis to inhibition by ultraviolet radiation (UVR) was estimated using biological weighting functions (BWFs) and a model that predicts photosynthesis under photosynthetically active radiation and UVR exposures. BWF results demonstrated that the sensitivity of photosynthesis to UVR was not significantly different between E. huxleyi cells grown under elevated and present CO2 concentrations. We propose that the acclimation to elevated CO2 conditions involves a physiological mechanism of regulation and allocation of energy and metabolites in the cell, which is also responsible for altering the sensitivity to UVR. In coccolithophores, this mechanism might be affected by the decrease in the calcification rates.
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Affiliation(s)
- M Rosario Lorenzo
- Department of Ecology, Faculty of Sciences, University of Málaga, Bulevar Louis Pasteur s/n, Málaga, 29071, Spain
| | - Patrick J Neale
- Smithsonian Environmental Research Center, 647 Contees Wharf Rd, Edgewater, Maryland, 21037, USA
| | - Cristina Sobrino
- Department of Ecology and Animal Biology, Faculty of Sciences, University of Vigo, Campus Lagoas-Marcosende, 36310, Vigo, Spain
| | - Pablo León
- Marine Scotland Science, Marine Laboratory, 375 Victoria Road, Aberdeen, AB11 9DB, UK
| | - Víctor Vázquez
- Department of Ecology, Faculty of Sciences, University of Málaga, Bulevar Louis Pasteur s/n, Málaga, 29071, Spain
| | - Eileen Bresnan
- Marine Scotland Science, Marine Laboratory, 375 Victoria Road, Aberdeen, AB11 9DB, UK
| | - María Segovia
- Department of Ecology, Faculty of Sciences, University of Málaga, Bulevar Louis Pasteur s/n, Málaga, 29071, Spain
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8
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Metabolomic and transcriptomic analyses reveal the effects of ultraviolet radiation deprivation on Isochrysis galbana at high temperature. ALGAL RES 2019. [DOI: 10.1016/j.algal.2019.101424] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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9
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Phytoplankton as Key Mediators of the Biological Carbon Pump: Their Responses to a Changing Climate. SUSTAINABILITY 2018. [DOI: 10.3390/su10030869] [Citation(s) in RCA: 51] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
The world’s oceans are a major sink for atmospheric carbon dioxide (CO2). The biological carbon pump plays a vital role in the net transfer of CO2 from the atmosphere to the oceans and then to the sediments, subsequently maintaining atmospheric CO2 at significantly lower levels than would be the case if it did not exist. The efficiency of the biological pump is a function of phytoplankton physiology and community structure, which are in turn governed by the physical and chemical conditions of the ocean. However, only a few studies have focused on the importance of phytoplankton community structure to the biological pump. Because global change is expected to influence carbon and nutrient availability, temperature and light (via stratification), an improved understanding of how phytoplankton community size structure will respond in the future is required to gain insight into the biological pump and the ability of the ocean to act as a long-term sink for atmospheric CO2. This review article aims to explore the potential impacts of predicted changes in global temperature and the carbonate system on phytoplankton cell size, species and elemental composition, so as to shed light on the ability of the biological pump to sequester carbon in the future ocean.
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Li ZK, Dai GZ, Juneau P, Qiu BS. Different physiological responses of cyanobacteria to ultraviolet-B radiation under iron-replete and iron-deficient conditions: Implications for underestimating the negative effects of UV-B radiation. JOURNAL OF PHYCOLOGY 2017; 53:425-436. [PMID: 28164281 DOI: 10.1111/jpy.12517] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/28/2016] [Accepted: 12/19/2016] [Indexed: 06/06/2023]
Abstract
Iron deficiency has been considered one of the main limiting factors of phytoplankton productivity in some aquatic systems including oceans and lakes. Concomitantly, solar ultraviolet-B radiation has been shown to have both deleterious and positive impacts on phytoplankton productivity. However, how iron-deficient cyanobacteria respond to UV-B radiation has been largely overlooked in aquatic systems. In this study, physiological responses of four cyanobacterial strains (Microcystis and Synechococcus), which are widely distributed in freshwater or marine systems, were investigated under different UV-B irradiances and iron conditions. The growth, photosynthetic pigment composition, photosynthetic activity, and nonphotochemical quenching of the different cyanobacterial strains were drastically altered by enhanced UV-B radiation under iron-deficient conditions, but were less affected under iron-replete conditions. Intracellular reactive oxygen species (ROS) and iron content increased and decreased, respectively, with increased UV-B radiation under iron-deficient conditions for both Microcystis aeruginosa FACHB 912 and Synechococcus sp. WH8102. On the contrary, intracellular ROS and iron content of these two strains remained constant and increased, respectively, with increased UV-B radiation under iron-replete conditions. These results indicate that iron-deficient cyanobacteria are more susceptible to enhanced UV-B radiation. Therefore, UV-B radiation probably plays an important role in influencing primary productivity in iron-deficient aquatic systems, suggesting that its effects on the phytoplankton productivity may be underestimated in iron-deficient regions around the world.
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Affiliation(s)
- Zheng-Ke Li
- School of Life Sciences, Hubei Key Laboratory of Genetic Regulation and Integrative Biology, Central China Normal University, Wuhan, Hubei, 430079, China
| | - Guo-Zheng Dai
- School of Life Sciences, Hubei Key Laboratory of Genetic Regulation and Integrative Biology, Central China Normal University, Wuhan, Hubei, 430079, China
| | - Philippe Juneau
- Department of Biological Sciences, GRIL-TOXEN, Ecotoxicology of Aquatic Microorganisms Laboratory, Université du Québec à Montréal, CP8888 Succursale Centre-ville, Montréal, Québec, Canada, H3C 3P8
| | - Bao-Sheng Qiu
- School of Life Sciences, Hubei Key Laboratory of Genetic Regulation and Integrative Biology, Central China Normal University, Wuhan, Hubei, 430079, China
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Li Y, Zhuang S, Wu Y, Ren H, Chen F, Lin X, Wang K, Beardall J, Gao K. Ocean acidification modulates expression of genes and physiological performance of a marine diatom. PLoS One 2017; 12:e0170970. [PMID: 28192486 PMCID: PMC5305191 DOI: 10.1371/journal.pone.0170970] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2016] [Accepted: 01/13/2017] [Indexed: 12/03/2022] Open
Abstract
Ocean Acidification (OA) is known to affect various aspects of physiological performances of diatoms, but little is known about the underlining molecular mechanisms involved. Here, we show that in the model diatom Phaeodactylum tricornutum, the expression of key genes associated with photosynthetic light harvesting as well as those encoding Rubisco, carbonic anhydrase, NADH dehydrogenase and nitrite reductase, are modulated by OA (1000 μatm, pHnbs 7.83). Growth and photosynthetic carbon fixation were enhanced by elevated CO2. OA treatment decreased the expression of β-carbonic anhydrase (β-ca), which functions in balancing intracellular carbonate chemistry and the CO2 concentrating mechanism (CCM). The expression of the genes encoding fucoxanthin chlorophyll a/c protein (lhcf type (fcp)), mitochondrial ATP synthase (mtATP), ribulose-1, 5-bisphosphate carboxylase/oxygenase large subunit gene (rbcl) and NADH dehydrogenase subunit 2 (ndh2), were down-regulated during the first four days (< 8 generations) after the cells were transferred from LC (cells grown under ambient air condition; 390 μatm; pHnbs 8.19) to OA conditions, with no significant difference between LC and HC treatments with the time elapsed. The expression of nitrite reductase (nir) was up-regulated by the OA treatment. Additionally, the genes for these proteins (NiR, FCP, mtATP synthase, β-CA) showed diel expression patterns. It appeared that the enhanced photosynthetic and growth rates under OA could be attributed to stimulated nitrogen assimilation, increased CO2 availability or saved energy from down-regulation of the CCM and consequently lowered cost of protein synthesis versus that of non-nitrogenous cell components.
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Affiliation(s)
- Yahe Li
- State Key Laboratory of Marine Environmental Science (Xiamen University), College of Ocean and Earth Sciences, Xiamen University, Xiamen, China
| | - Shufang Zhuang
- State Key Laboratory of Marine Environmental Science (Xiamen University), College of Ocean and Earth Sciences, Xiamen University, Xiamen, China
| | - Yaping Wu
- State Key Laboratory of Marine Environmental Science (Xiamen University), College of Ocean and Earth Sciences, Xiamen University, Xiamen, China
| | - Honglin Ren
- Key Laboratory of Zoonosis Research, Ministry of Education, Institute of Zoonosis, Jilin University, Changchun, China
| | - Fangyi Chen
- State Key Laboratory of Marine Environmental Science (Xiamen University), College of Ocean and Earth Sciences, Xiamen University, Xiamen, China
| | - Xin Lin
- State Key Laboratory of Marine Environmental Science (Xiamen University), College of Ocean and Earth Sciences, Xiamen University, Xiamen, China
| | - Kejian Wang
- State Key Laboratory of Marine Environmental Science (Xiamen University), College of Ocean and Earth Sciences, Xiamen University, Xiamen, China
| | - John Beardall
- School of Biological Sciences, Monash University, Clayton, Victoria, Australia
| | - Kunshan Gao
- State Key Laboratory of Marine Environmental Science (Xiamen University), College of Ocean and Earth Sciences, Xiamen University, Xiamen, China
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12
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Limited phosphorus availability is the Achilles heel of tropical reef corals in a warming ocean. Sci Rep 2016; 6:31768. [PMID: 27531136 PMCID: PMC4987665 DOI: 10.1038/srep31768] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2016] [Accepted: 07/27/2016] [Indexed: 12/04/2022] Open
Abstract
During the 20th century, seawater temperatures have significantly increased, leading to profound alterations in biogeochemical cycles and ecosystem processes. Elevated temperatures have also caused massive bleaching (symbiont/pigment loss) of autotrophic symbioses, such as in coral-dinoflagellate association. As symbionts provide most nutrients to the host, their expulsion during bleaching induces host starvation. However, with the exception of carbon, the nutritional impact of bleaching on corals is still unknown, due to the poorly understood requirements in inorganic nutrients during stress. We therefore assessed the uptake rates of nitrogen and phosphate by five coral species maintained under normal and thermal stress conditions. Our results showed that nitrogen acquisition rates were significantly reduced during thermal stress, while phosphorus uptake rates were significantly increased in most species, suggesting a key role of this nutrient. Additional experiments showed that during thermal stress, phosphorus was required to maintain symbiont density and photosynthetic rates, as well as to enhance the translocation and retention of carbon within the host tissue. These findings shed new light on the interactions existing between corals and inorganic nutrients during thermal stress, and highlight the importance of phosphorus for symbiont health.
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Puente-Sánchez F, Olsson S, Gómez-Rodriguez M, Souza-Egipsy V, Altamirano-Jeschke M, Amils R, Parro V, Aguilera A. Solar Radiation Stress in Natural Acidophilic Biofilms of Euglena mutabilis Revealed by Metatranscriptomics and PAM Fluorometry. Protist 2016; 167:67-81. [DOI: 10.1016/j.protis.2015.12.003] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2015] [Revised: 12/18/2015] [Accepted: 12/21/2015] [Indexed: 12/27/2022]
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14
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Wu Y, Li Z, Du W, Gao K. Physiological response of marine centric diatoms to ultraviolet radiation, with special reference to cell size. JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY B-BIOLOGY 2015; 153:1-6. [DOI: 10.1016/j.jphotobiol.2015.08.035] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/27/2015] [Revised: 08/20/2015] [Accepted: 08/21/2015] [Indexed: 12/15/2022]
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15
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Carrillo P, Medina-Sánchez JM, Herrera G, Durán C, Segovia M, Cortés D, Salles S, Korbee N, L. Figueroa F, Mercado JM. Interactive Effect of UVR and Phosphorus on the Coastal Phytoplankton Community of the Western Mediterranean Sea: Unravelling Eco-Physiological Mechanisms. PLoS One 2015; 10:e0142987. [PMID: 26599583 PMCID: PMC4658109 DOI: 10.1371/journal.pone.0142987] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2015] [Accepted: 10/29/2015] [Indexed: 12/17/2022] Open
Abstract
Some of the most important effects of global change on coastal marine systems include increasing nutrient inputs and higher levels of ultraviolet radiation (UVR, 280-400 nm), which could affect primary producers, a key trophic link to the functioning of marine food webs. However, interactive effects of both factors on the phytoplankton community have not been assessed for the Mediterranean Sea. An in situ factorial experiment, with two levels of ultraviolet solar radiation (UVR+PAR vs. PAR) and nutrients (control vs. P-enriched), was performed to evaluate single and UVR×P effects on metabolic, enzymatic, stoichiometric and structural phytoplanktonic variables. While most phytoplankton variables were not affected by UVR, dissolved phosphatase (APAEX) and algal P content increased in the presence of UVR, which was interpreted as an acclimation mechanism of algae to oligotrophic marine waters. Synergistic UVR×P interactive effects were positive on photosynthetic variables (i.e., maximal electron transport rate, ETRmax), but negative on primary production and phytoplankton biomass because the pulse of P unmasked the inhibitory effect of UVR. This unmasking effect might be related to greater photodamage caused by an excess of electron flux after a P pulse (higher ETRmax) without an efficient release of carbon as the mechanism to dissipate the reducing power of photosynthetic electron transport.
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Affiliation(s)
- Presentación Carrillo
- Instituto del Agua, Universidad de Granada, Granada, Spain
- Departamento de Ecología, Facultad de Ciencias, Universidad de Granada, Granada, Spain
| | - Juan M. Medina-Sánchez
- Instituto del Agua, Universidad de Granada, Granada, Spain
- Departamento de Ecología, Facultad de Ciencias, Universidad de Granada, Granada, Spain
| | | | - Cristina Durán
- Instituto del Agua, Universidad de Granada, Granada, Spain
| | - María Segovia
- Departamento de Ecología, Facultad de Ciencias, Universidad de Málaga, Málaga, Spain
| | - Dolores Cortés
- Centro Oceanográfico de Málaga, Instituto Español de Oceanografía Fuengirola, Málaga, Spain
| | - Soluna Salles
- Centro Oceanográfico de Málaga, Instituto Español de Oceanografía Fuengirola, Málaga, Spain
| | - Nathalie Korbee
- Departamento de Ecología, Facultad de Ciencias, Universidad de Málaga, Málaga, Spain
| | - Félix L. Figueroa
- Departamento de Ecología, Facultad de Ciencias, Universidad de Málaga, Málaga, Spain
| | - Jesús M. Mercado
- Centro Oceanográfico de Málaga, Instituto Español de Oceanografía Fuengirola, Málaga, Spain
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García-Gómez C, Gordillo FJL, Palma A, Lorenzo MR, Segovia M. Elevated CO2 alleviates high PAR and UV stress in the unicellular chlorophyte Dunaliella tertiolecta. Photochem Photobiol Sci 2015; 13:1347-58. [PMID: 25043601 DOI: 10.1039/c4pp00044g] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The effects of increased CO2 and irradiance on the physiological performance of the chlorophyte Dunaliella tertiolecta were studied at different PAR and UVR (UVA + UVB) irradiances, simulating the solar radiation at different depths, at present (390 ppmv, LC) and predicted CO2 levels for the year 2100 (1000 ppmv, HC). Elevated CO2 resulted in higher optimum and effective quantum yields (F(v)/F(m) and ϕPSII, respectively), electron transport rates (ETR) and specific growth rates (μ). Cell stress was alleviated in HC with respect to LC as evidenced by a decrease in reactive oxygen species (ROS) accumulation. DNA damage showed a 42-fold increase in cyclobutane-pyrimidine dimer (CPD) formation under the highest irradiance (1100 μmol quanta m(-2) s(-1)) in LC with respect to the lowest irradiance (200 μmol quanta m(-2) s(-1)). Photolyase (CII-PCD-PL) gene expression was upregulated under HC resulting in a drastic decrease in CPD accumulation to only 25% with respect to LC. Proliferating cell nuclear antigen (PCNA) accumulation was always higher in HC and the accumulation pattern indicated its involvement in repair or growth depending on the irradiance dose. The repressor of silencing (ROS1) was only marginally involved in the response, suggesting that photoreactivation was the most relevant mechanism to overcome UVR damage. Our results demonstrate that future scenarios of global change result in alleviation of irradiance stress by CO2-induced photoprotection in D. tertiolecta.
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Affiliation(s)
- Candela García-Gómez
- Department of Ecology, Faculty of Sciences, University of Málaga, Bvd. Louis Pasteur s/n, 29010 Málaga, Spain.
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Interactive Effects of Temperature and UV Radiation on Photosynthesis of Chlorella Strains from Polar, Temperate and Tropical Environments: Differential Impacts on Damage and Repair. PLoS One 2015; 10:e0139469. [PMID: 26427046 PMCID: PMC4591349 DOI: 10.1371/journal.pone.0139469] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2015] [Accepted: 09/13/2015] [Indexed: 11/20/2022] Open
Abstract
Global warming and ozone depletion, and the resulting increase of ultraviolet radiation (UVR), have far-reaching impacts on biota, especially affecting the algae that form the basis of the food webs in aquatic ecosystems. The aim of the present study was to investigate the interactive effects of temperature and UVR by comparing the photosynthetic responses of similar taxa of Chlorella from Antarctic (Chlorella UMACC 237), temperate (Chlorella vulgaris UMACC 248) and tropical (Chlorella vulgaris UMACC 001) environments. The cultures were exposed to three different treatments: photosynthetically active radiation (PAR; 400–700 nm), PAR plus ultraviolet-A (320–400 nm) radiation (PAR + UV-A) and PAR plus UV-A and ultraviolet-B (280–320 nm) radiation (PAR + UV-A + UV-B) for one hour in incubators set at different temperatures. The Antarctic Chlorella was exposed to 4, 14 and 20°C. The temperate Chlorella was exposed to 11, 18 and 25°C while the tropical Chlorella was exposed to 24, 28 and 30°C. A pulse-amplitude modulated (PAM) fluorometer was used to assess the photosynthetic response of microalgae. Parameters such as the photoadaptive index (Ek) and light harvesting efficiency (α) were determined from rapid light curves. The damage (k) and repair (r) rates were calculated from the decrease in ΦPSIIeff over time during exposure response curves where cells were exposed to the various combinations of PAR and UVR, and fitting the data to the Kok model. The results showed that UV-A caused much lower inhibition than UV-B in photosynthesis in all Chlorella isolates. The three isolates of Chlorella from different regions showed different trends in their photosynthesis responses under the combined effects of UVR (PAR + UV-A + UV-B) and temperature. In accordance with the noted strain-specific characteristics, we can conclude that the repair (r) mechanisms at higher temperatures were not sufficient to overcome damage caused by UVR in the Antarctic Chlorella strain, suggesting negative effects of global climate change on microalgae inhabiting (circum-) polar regions. For temperate and tropical strains of Chlorella, damage from UVR was independent of temperature but the repair constant increased with increasing temperature, implying an improved ability of these strains to recover from UVR stress under global warming.
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Häder DP, Villafañe VE, Helbling EW. Productivity of aquatic primary producers under global climate change. Photochem Photobiol Sci 2015; 13:1370-92. [PMID: 25191675 DOI: 10.1039/c3pp50418b] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The productivity of aquatic primary producers depends on a number of biotic and abiotic factors, such as pH, CO2 concentration, temperature, nutrient availability, solar UV and PAR irradiances, mixing frequency as well as herbivore pressure and the presence of viruses, among others. The effects of these factors, within a climate change context, may be additive, synergistic or antagonistic. Since some of them, e.g. solar radiation and temperature, vary along a latitudinal gradient, this perspective about the effects of global climate change on primary producers will consider ecosystems individually, separated into polar (Arctic and Antarctic), temperate and tropical waters. As coastal waters are characterized by lower light penetration and higher DOM and nutrient concentrations, they are considered in a separate section. Freshwater systems are also governed by different conditions and therefore also treated in their own section. Overall, we show that although there are general common trends of changes in variables associated with global change (e.g. the impact of UVR on photosynthesis tends to decrease with increasing temperature and nutrient input), the responses of aquatic primary producers have great variability in the different ecosystems across latitudes. This is mainly due to direct or indirect effects associated with physico-chemical changes that occur within water bodies. Therefore we stress the need for regional predictions on the responses of primary producers to climate change as it is not warranted to extrapolate from one system to another.
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Varshney P, Mikulic P, Vonshak A, Beardall J, Wangikar PP. Extremophilic micro-algae and their potential contribution in biotechnology. BIORESOURCE TECHNOLOGY 2015; 184:363-372. [PMID: 25443670 DOI: 10.1016/j.biortech.2014.11.040] [Citation(s) in RCA: 122] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/06/2014] [Revised: 11/05/2014] [Accepted: 11/07/2014] [Indexed: 05/18/2023]
Abstract
Micro-algae have potential as sustainable sources of energy and products and alternative mode of agriculture. However, their mass cultivation is challenging due to low survival under harsh outdoor conditions and competition from other, undesired, species. Extremophilic micro-algae have a role to play by virtue of their ability to grow under acidic or alkaline pH, high temperature, light, CO2 level and metal concentration. In this review, we provide several examples of potential biotechnological applications of extremophilic micro-algae and the ranges of tolerated extremes. We also discuss the adaptive mechanisms of tolerance to these extremes. Analysis of phylogenetic relationship of the reported extremophiles suggests certain groups of the Kingdom Protista to be more tolerant to extremophilic conditions than other taxa. While extremophilic microalgae are beginning to be explored, much needs to be done in terms of the physiology, molecular biology, metabolic engineering and outdoor cultivation trials before their true potential is realized.
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Affiliation(s)
- Prachi Varshney
- Department of Chemical Engineering, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India; School of Biological Sciences, Monash University, Clayton, Victoria 3800, Australia; IIT Bombay Monash Research Academy, CSE Building, 2nd Floor, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India
| | - Paulina Mikulic
- School of Biological Sciences, Monash University, Clayton, Victoria 3800, Australia
| | - Avigad Vonshak
- Jacob Blaustein Institutes for Desert Research, Ben Gurion University, Sede Boqer Campus, 84990, Israel
| | - John Beardall
- School of Biological Sciences, Monash University, Clayton, Victoria 3800, Australia
| | - Pramod P Wangikar
- Department of Chemical Engineering, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India.
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Gordillo FJL, Aguilera J, Wiencke C, Jiménez C. Ocean acidification modulates the response of two Arctic kelps to ultraviolet radiation. JOURNAL OF PLANT PHYSIOLOGY 2015; 173:41-50. [PMID: 25462077 DOI: 10.1016/j.jplph.2014.09.008] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/06/2014] [Revised: 09/19/2014] [Accepted: 09/20/2014] [Indexed: 06/04/2023]
Abstract
The combined effects of ocean acidification and ultraviolet radiation (UVR) have been studied in the kelps Alaria esculenta and Saccharina latissima from Kongsfjorden (Svalbard), two major components of the Arctic macroalgal community, in order to assess their potential to thrive in a changing environment. Overall results revealed synergistic effects, however with a different amplitude in the respective species. Changes in growth, internal N, C:N ratio, pigments, optimum quantum yield (Fv/Fm) and electron transport rates (ETR) following CO2 enrichment and/or UVR were generally more pronounced in S. latissima than in A. esculenta. The highest growth rates were recorded under simultaneous CO2 enrichment and UVR in both species. UVR-mediated changes in pigment content were partially prevented under elevated CO2 in both species. Similarly, UVR led to increased photosynthetic efficiency (α) and ETR only if CO2 was not elevated in A. esculenta and even under high CO2 in S. latissima. Increased CO2 did not inhibit external carbonic anhydrase (eCA) activity in the short-term but in the mid-term, indicating a control through acclimation of photosynthesis rather than a direct inhibition of eCA by CO2. The higher benefit of simultaneous CO2 enrichment and UVR for S. latissima respect to A. esculenta seems to involve higher C and N assimilation efficiency, as well as higher ETR, despite a more sensitive Fv/Fm. The differential responses shown by these two species indicate that ongoing ocean acidification and UVR could potentially change the dominance at lower depths (4-6m), which will eventually drive changes at the community level in the Arctic coastal ecosystem. These results support an existing consideration of S. latissima as a winner species in the global change scenario.
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Affiliation(s)
- Francisco J L Gordillo
- Departamento de Ecología, Facultad de Ciencias, Universidad de Málaga, Bulevar Louis Pasteur s/n, 29010 Málaga, Spain.
| | - José Aguilera
- Departamento de Dermatología, Facultad de Medicina, Universidad de Málaga, Bulevar Louis Pasteur s/n, 29010 Málaga, Spain
| | - Christian Wiencke
- Alfred Wegener Institute, Am Handelshafen 12, D-27570 Bremerhaven, Germany
| | - Carlos Jiménez
- Departamento de Ecología, Facultad de Ciencias, Universidad de Málaga, Bulevar Louis Pasteur s/n, 29010 Málaga, Spain
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21
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Xing T, Gao K, Beardall J. Response of Growth and Photosynthesis ofEmiliania huxleyito Visible and UV Irradiances under Different Light Regimes. Photochem Photobiol 2015; 91:343-9. [DOI: 10.1111/php.12403] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2014] [Accepted: 12/03/2014] [Indexed: 11/27/2022]
Affiliation(s)
- Tao Xing
- State Key Laboratory of Marine Environmental Science; Xiamen University; Xiamen China
| | - Kunshan Gao
- State Key Laboratory of Marine Environmental Science; Xiamen University; Xiamen China
| | - John Beardall
- School of Biological Sciences; Monash University; Clayton Vic. Australia
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22
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Xu K, Gao K. Solar UV Irradiances Modulate Effects of Ocean Acidification on the CoccolithophoridEmiliania huxleyi. Photochem Photobiol 2014; 91:92-101. [DOI: 10.1111/php.12363] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2014] [Accepted: 10/12/2014] [Indexed: 01/08/2023]
Affiliation(s)
- Kai Xu
- State Key Laboratory of Marine Environmental Science; Xiamen University; Xiamen China
- Department of Biological Sciences; University of Southern California; Los Angeles CA
| | - Kunshan Gao
- State Key Laboratory of Marine Environmental Science; Xiamen University; Xiamen China
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Wu Y, Campbell DA, Gao K. Faster recovery of a diatom from UV damage under ocean acidification. JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY B-BIOLOGY 2014; 140:249-54. [DOI: 10.1016/j.jphotobiol.2014.08.006] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/11/2014] [Revised: 08/04/2014] [Accepted: 08/07/2014] [Indexed: 11/26/2022]
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24
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Häder DP, Richter PR, Villafañe VE, Helbling EW. Influence of light history on the photosynthetic and motility responses of Gymnodinium chlorophorum exposed to UVR and different temperatures. JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY B-BIOLOGY 2014; 138:273-81. [PMID: 24998868 DOI: 10.1016/j.jphotobiol.2014.05.020] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/25/2014] [Revised: 05/20/2014] [Accepted: 05/26/2014] [Indexed: 12/01/2022]
Abstract
In the wake of global climate change, phytoplankton productivity and species composition is expected to change due to altered external conditions such as temperature, nutrient accessibility, pH and exposure to solar visible (PAR) and ultraviolet radiation (UVR). The previous light history is also of importance for the performance of phytoplankton cells. In order to assess the combined impacts of UVR and temperature on the dinoflagellate Gymnodinium chlorophorum we analyzed the effective photochemical quantum yield (Y), relative electron transport rate vs. irradiance curves (rETR vs. I), percentage of motile cells and swimming velocity. Cells were grown at three different temperatures (15, 20 and 25 °C) and two PAR intensities: low light (LL, 100 μmol photons m(-2) s(-1)) and high light (HL, 250 μmol photons m(-2) s(-1)). Pre-acclimated cells were then exposed to either PAR only (P), PAR+UV-A (PA) or PAR+UV-A+UV-B (PAB) radiation at two different irradiances, followed by a recovery period in darkness. The Y decreased during exposure, being least inhibited in P and most in PAB treatments. Inhibition was higher and recovery slower in LL-grown cells than in HL-grown cells at 15° and 20 °C, but the opposite occurred at 25 °C, when exposed to high irradiances. Maximal values of rETR were determined at t0 as compared to the different (before and after exposure) radiation treatments. The effects of temperature and UVR on rETR were antagonistic in LL-grown cells (i.e., less UVR inhibition at higher temperature), while it was synergistic in HL cells. Swimming velocity and percentage of motile cells were not affected at all tested temperatures and exposure regimes, independent of the light history. Our results indicate that, depending on the previous light history, increased temperature and UVR as predicted under climate change conditions, can have different interactions thus conditioning the photosynthetic response of G. chlorophorum.
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Affiliation(s)
| | - Peter R Richter
- Friedrich-Alexander Universität, Department Biologie, Lehrstuhl für Zellbiologie, AG für Gravitationsbiologie, Staudtstr. 5, 90158 Erlangen, Germany.
| | - Virginia E Villafañe
- ESTACIÓN de Fotobiología Playa Unión, Casilla de Correo 15, U9103ZAA Rawson, Chubut, Argentina.
| | - E Walter Helbling
- ESTACIÓN de Fotobiología Playa Unión, Casilla de Correo 15, U9103ZAA Rawson, Chubut, Argentina.
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Gao K, Campbell DA. Photophysiological responses of marine diatoms to elevated CO 2 and decreased pH: a review. FUNCTIONAL PLANT BIOLOGY : FPB 2014; 41:449-459. [PMID: 32481004 DOI: 10.1071/fp13247] [Citation(s) in RCA: 65] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/21/2013] [Accepted: 12/24/2013] [Indexed: 05/19/2023]
Abstract
Diatoms dominate nearly half of current oceanic productivity, so their responses to ocean acidification are of general concern regarding future oceanic carbon sequestration. Community, mesocosm and laboratory studies show a range of diatom growth and photophysiological responses to increasing pCO2. Nearly 20 studies on effects of elevated pCO2 on diatoms have shown stimulations, no effects or inhibitions of growth rates. These differential responses could result from differences in experimental setups, cell densities, levels of light and temperature, but also from taxon-specific physiology. Generally, ocean acidification treatments of lowered pH with elevated CO2 stimulate diatom growth under low to moderate levels of light, but lead to growth inhibition when combined with excess light. Additionally, diatom cell sizes and their co-varying metabolic rates can influence responses to increasing pCO2 and decreasing pH, although cell size effects are confounded with taxonomic specificities in cell structures and metabolism. Here we summarise known diatom growth and photophysiological responses to increasing pCO2 and decreasing pH, and discuss some reasons for the diverse responses observed across studies.
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Affiliation(s)
- Kunshan Gao
- State Key Laboratory of Marine Environmental Science, Xiamen University, 361005 Xiamen, China
| | - Douglas A Campbell
- Department of Biology, Mount Allison University, Sackville, NB E4L 1G7, Canada
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Santos AL, Baptista I, Gomes NCM, Henriques I, Almeida A, Correia A, Cunha A. Contribution of chemical water properties to the differential responses of bacterioneuston and bacterioplankton to ultraviolet-B radiation. FEMS Microbiol Ecol 2013; 87:517-35. [PMID: 24164491 DOI: 10.1111/1574-6941.12239] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2013] [Revised: 09/24/2013] [Accepted: 10/21/2013] [Indexed: 11/26/2022] Open
Abstract
The surface microlayer (SML) is characterized by different physicochemical properties from underlying waters (UW). However, whether these differences in abiotic factors underlie the distinct sensitivity of bacterioneuston (i.e. SML bacteria) and bacterioplankton to environmental stressors remains to be addressed. We investigated the contribution of abiotic factors to the UV-B sensitivity of bacterioneuston and bacterioplankton. Nutrients (especially nitrogen and phosphate) emerged as important determinants of bacterial UV-B sensitivity. The role of particles, nutrients, and dissolved organic components on bacterial UV-B sensitivity was further evaluated using dilution cultures. Filtered samples were twofold more UV sensitive than unfiltered samples, suggesting a UV-protective effect of particles. High nutrient concentrations attenuated bacterial UV-B sensitivity (up to 40%), compared with unamended conditions, by influencing bacterial physiology and/or community composition. Suspending cells in natural water, particularly from the SML, also attenuated UV-B sensitivity (up to 23%), compared with suspension in an artificial mineral solution. Bioassays using Pseudomonas sp. strain NT5I1.2B revealed that chemical water properties influence UV-induced oxidative damage. UV-B sensitivity was associated with high cell-specific activities. The chemical environment of the SML and UW influences UV-B effects on the corresponding bacterial communities. Maintaining low cell activities might be advantageous in stressful environments, like the SML.
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Affiliation(s)
- Ana L Santos
- Department of Biology and CESAM, University of Aveiro, Aveiro, Portugal
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Prince EK, Irmer F, Pohnert G. Domoic acid improves the competitive ability of Pseudo-nitzschia delicatissima against the diatom Skeletonema marinoi. Mar Drugs 2013; 11:2398-412. [PMID: 23852091 PMCID: PMC3736430 DOI: 10.3390/md11072398] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2013] [Revised: 06/19/2013] [Accepted: 06/28/2013] [Indexed: 11/16/2022] Open
Abstract
Because domoic acid, a neurotoxic secondary metabolite produced by marine diatoms in the genus Pseudo-nitzschia, is hypothesized to be part of a high affinity iron uptake system, we investigated whether domoic acid could improve the competitive ability of Pseudo-nitzschia delicatissima, and whether the availability of iron changed the outcome of competition experiments. We found that domoic acid had a slight negative effect on growth of the diatom Skeletonema marinoi when it was grown in monocultures. However, when S. marinoi was cultured with P. delicatissima the presence of domoic acid resulted in a reduction of S. marinoi cells by up to 38% and an increase in P. delicatissima cell numbers by up to 17% under iron replete conditions. Similar effects were not observed in low iron treatments. Domoic acid was not taken up by P. delicatissima cells. Overall, our results indicate that domoic acid can improve the competitive ability of Pseudo-nitzschia spp. and that iron is likely to be involved. This study provides an unusual example of indirect inhibition of competitor growth mediated by a secondary metabolite.
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Affiliation(s)
- Emily K. Prince
- Department of Mathematics, Sciences, and Technology, Paine College, 1235 15th Street, Augusta, GA 30901, USA
- Author to whom correspondence should be addressed; E-Mail: ; Tel.: +1-706-896-8108
| | - Friederike Irmer
- Institute for Inorganic and Analytical Chemistry, Friedrich Schiller University, Lessingstrasse 8, Jena 07743, Germany; E-Mails: (F.I.); (G.P.)
| | - Georg Pohnert
- Institute for Inorganic and Analytical Chemistry, Friedrich Schiller University, Lessingstrasse 8, Jena 07743, Germany; E-Mails: (F.I.); (G.P.)
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Li W, Gao K, Beardall J. Interactive effects of ocean acidification and nitrogen-limitation on the diatom Phaeodactylum tricornutum. PLoS One 2012; 7:e51590. [PMID: 23236517 PMCID: PMC3517544 DOI: 10.1371/journal.pone.0051590] [Citation(s) in RCA: 66] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2012] [Accepted: 11/05/2012] [Indexed: 11/28/2022] Open
Abstract
Climate change is expected to bring about alterations in the marine physical and chemical environment that will induce changes in the concentration of dissolved CO(2) and in nutrient availability. These in turn are expected to affect the physiological performance of phytoplankton. In order to learn how phytoplankton respond to the predicted scenario of increased CO(2) and decreased nitrogen in the surface mixed layer, we investigated the diatom Phaeodactylum tricornutum as a model organism. The cells were cultured in both low CO(2) (390 μatm) and high CO(2) (1000 μatm) conditions at limiting (10 μmol L(-1)) or enriched (110 μmol L(-1)) nitrate concentrations. Our study shows that nitrogen limitation resulted in significant decreases in cell size, pigmentation, growth rate and effective quantum yield of Phaeodactylum tricornutum, but these parameters were not affected by enhanced dissolved CO(2) and lowered pH. However, increased CO(2) concentration induced higher rETR(max) and higher dark respiration rates and decreased the CO(2) or dissolved inorganic carbon (DIC) affinity for electron transfer (shown by higher values for K(1/2 DIC) or K(1/2 CO2)). Furthermore, the elemental stoichiometry (carbon to nitrogen ratio) was raised under high CO(2) conditions in both nitrogen limited and nitrogen replete conditions, with the ratio in the high CO(2) and low nitrate grown cells being higher by 45% compared to that in the low CO(2) and nitrate replete grown ones. Our results suggest that while nitrogen limitation had a greater effect than ocean acidification, the combined effects of both factors could act synergistically to affect marine diatoms and related biogeochemical cycles in future oceans.
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Affiliation(s)
- Wei Li
- State Key Laboratory of Marine Environmental Science, Xiamen University, Xiamen, China
| | - Kunshan Gao
- State Key Laboratory of Marine Environmental Science, Xiamen University, Xiamen, China
| | - John Beardall
- School of Biological Sciences, Monash University, Clayton, Victoria, Australia
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Xu J, Gao K. Future CO2-induced ocean acidification mediates the physiological performance of a green tide alga. PLANT PHYSIOLOGY 2012; 160:1762-9. [PMID: 23129205 PMCID: PMC3510108 DOI: 10.1104/pp.112.206961] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
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Steven B, Gallegos-Graves LV, Yeager CM, Belnap J, Evans RD, Kuske CR. Dryland biological soil crust cyanobacteria show unexpected decreases in abundance under long-term elevated CO2. Environ Microbiol 2012; 14:3247-58. [DOI: 10.1111/1462-2920.12011] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2012] [Revised: 09/11/2012] [Accepted: 09/28/2012] [Indexed: 11/28/2022]
Affiliation(s)
- Blaire Steven
- Bioscience Division; Los Alamos National Laboratory; Los Alamos; NM; 87545; USA
| | | | - Chris M. Yeager
- Bioscience Division; Los Alamos National Laboratory; Los Alamos; NM; 87545; USA
| | - Jayne Belnap
- US Geological Service; Southwest Biological Science Center; Moab; UT; 84532; USA
| | - R. David Evans
- School of Biological Sciences; Washington State University; Pullman; WA; 99163; USA
| | - Cheryl R. Kuske
- Bioscience Division; Los Alamos National Laboratory; Los Alamos; NM; 87545; USA
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Llewellyn CA, White DA, Martinez-Vincente V, Tarran G, Smyth TJ. Distribution of mycosporine-like amino acids along a surface water meridional transect of the Atlantic. MICROBIAL ECOLOGY 2012; 64:320-333. [PMID: 22438039 DOI: 10.1007/s00248-012-0038-6] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/12/2011] [Accepted: 02/17/2012] [Indexed: 05/31/2023]
Abstract
The composition and abundance of mycosporine-like amino acids (MAAs) were investigated in the surface waters along a 13,000-km meridional transect (52° N to 45° S) in the Atlantic Ocean (Atlantic Meridional Transect programme: Cruise AMT 18: 4/10/2008-10/11/2008). MAAs were ubiquitous along the transect, although the composition of the MAAs was variable. Highest concentrations were in the far south (below 40° S; MAA >1 μg L(-1)) and in north subtropical equatorial region (NER: 0-25° N; MAA up to 0.8 μg L(-1)). Highest MAA relative to chlorophyll-a occurred in the NER (MAA/chl-a ratio between 2 and 5). MAA/chl-a significantly correlated with the preceding month's mean daily UV dose and with UV-B/UV-A. In the far south, high MAA concentrations coincided with high phytoplankton biomass, high nutrients and a deep mixed layer associated with the austral spring. Here, the phytoplankton community was dominated by micro- and nano-eukaryotes. At the NER, the high MAA/chl-a coincided with low nutrient concentrations, a shallow mixed layer depth (20-70 m) and to a lesser extent to a shallow nitracline (40-90 m). Here, the phytoplankton consisted primarily of picophytoplankton (0-0.2 μm), dominated by the pico-cyanobacteria Synechococcus sp. and Prochlorococcus sp. and by the nitrogen fixing filamentous cyanobacterium Trichodesmium. The low nitrate concentrations (<0.1 μmol L(-1)) at the NER suggest that nitrogen fixation was required for MAA production. Specific MAAs could not easily be assigned to particular groups of phytoplankton and we could not rule out the possibility that MAAs were associated with symbiotic cyanobacteria contained within heterotrophic dinoflagellates or diatoms.
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Affiliation(s)
- Carole A Llewellyn
- Plymouth Marine Laboratory, Prospect Place, The Hoe, Plymouth, PL1 3DH, Devon, UK.
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Fields DM, Durif CMF, Bjelland RM, Shema SD, Skiftesvik AB, Browman HI. Grazing rates of Calanus finmarchicus on Thalassiosira weissflogii cultured under different levels of ultraviolet radiation. PLoS One 2011; 6:e26333. [PMID: 22028858 PMCID: PMC3196560 DOI: 10.1371/journal.pone.0026333] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2011] [Accepted: 09/25/2011] [Indexed: 11/25/2022] Open
Abstract
UVB alters photosynthetic rate, fatty acid profiles and morphological characteristics of phytoplankton. Copepods, important grazers of primary production, select algal cells based upon their size, morphological traits, nutritional status, and motility. We investigated the grazing rates of the copepod Calanus finmarchicus on the diatom Thalassiosira weissflogii cultured under 3 levels of ultraviolet radiation (UVR): photosynthetically active radiation (PAR) only (4 kJ-m(-2)/day), and PAR supplemented with UVR radiation at two intensities (24 kJ-m(-2)/day and 48 kJ-m(-2)/day). There was no significant difference in grazing rates between the PAR only treatment and the lower UVR treatment. However, grazing rates were significantly (∼66%) higher for copepods feeding on cells treated with the higher level of UVR. These results suggest that a short-term increase in UVR exposure results in a significant increase in the grazing rate of copepods and, thereby, potentially alters the flow rate of organic matter through this component of the ecosystem.
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Affiliation(s)
- David M Fields
- Bigelow Laboratory for Ocean Sciences, West Boothbay Harbor, Maine, United States of America.
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Raven JA, Giordano M, Beardall J, Maberly SC. Algal and aquatic plant carbon concentrating mechanisms in relation to environmental change. PHOTOSYNTHESIS RESEARCH 2011; 109:281-296. [PMID: 21327536 DOI: 10.1007/s11120-011-9632-6] [Citation(s) in RCA: 67] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/15/2010] [Accepted: 02/01/2011] [Indexed: 05/30/2023]
Abstract
Carbon dioxide concentrating mechanisms (also known as inorganic carbon concentrating mechanisms; both abbreviated as CCMs) presumably evolved under conditions of low CO(2) availability. However, the timing of their origin is unclear since there are no sound estimates from molecular clocks, and even if there were, there are no proxies for the functioning of CCMs. Accordingly, we cannot use previous episodes of high CO(2) (e.g. the Palaeocene-Eocene Thermal Maximum) to indicate how organisms with CCMs responded. Present and predicted environmental change in terms of increased CO(2) and temperature are leading to increased CO(2) and HCO(3)(-) and decreased CO(3)(2-) and pH in surface seawater, as well as decreasing the depth of the upper mixed layer and increasing the degree of isolation of this layer with respect to nutrient flux from deeper waters. The outcome of these forcing factors is to increase the availability of inorganic carbon, photosynthetic active radiation (PAR) and ultraviolet B radiation (UVB) to aquatic photolithotrophs and to decrease the supply of the nutrients (combined) nitrogen and phosphorus and of any non-aeolian iron. The influence of these variations on CCM expression has been examined to varying degrees as acclimation by extant organisms. Increased PAR increases CCM expression in terms of CO(2) affinity, whilst increased UVB has a range of effects in the organisms examined; little relevant information is available on increased temperature. Decreased combined nitrogen supply generally increases CO(2) affinity, decreased iron availability increases CO(2) affinity, and decreased phosphorus supply has varying effects on the organisms examined. There are few data sets showing interactions amongst the observed changes, and even less information on genetic (adaptation) changes in response to the forcing factors. In freshwaters, changes in phytoplankton species composition may alter with environmental change with consequences for frequency of species with or without CCMs. The information available permits less predictive power as to the effect of the forcing factors on CCM expression than for their overall effects on growth. CCMs are currently not part of models as to how global environmental change has altered, and is likely to further alter, algal and aquatic plant primary productivity.
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Affiliation(s)
- John A Raven
- Division of Plant Sciences, University of Dundee at SCRI, Scottish Crop Research Institute, Invergowrie, Dundee, UK.
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Zepp RG, Erickson III DJ, Paul ND, Sulzberger B. Effects of solar UV radiation and climate change on biogeochemical cycling: interactions and feedbacks. Photochem Photobiol Sci 2011; 10:261-79. [DOI: 10.1039/c0pp90037k] [Citation(s) in RCA: 75] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
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Li G, Gao K, Gao G. Differential Impacts of Solar UV Radiation on Photosynthetic Carbon Fixation from the Coastal to Offshore Surface Waters in the South China Sea. Photochem Photobiol 2010; 87:329-34. [DOI: 10.1111/j.1751-1097.2010.00862.x] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Combined effects of solar UV radiation and CO2-induced seawater acidification on photosynthetic carbon fixation of phytoplankton assemblages in the South China Sea. ACTA ACUST UNITED AC 2010. [DOI: 10.1007/s11434-010-4119-y] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Ma Z, Li W, Gao K. Horizontal migration of Acartia pacifica Steuer (copepoda) in response to UV-radiation. JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY B-BIOLOGY 2010; 101:233-7. [PMID: 20696590 DOI: 10.1016/j.jphotobiol.2010.07.008] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/06/2010] [Revised: 07/09/2010] [Accepted: 07/14/2010] [Indexed: 11/15/2022]
Affiliation(s)
- Z Ma
- East China Sea Fisheries Research Institute, Chinese Academy of Fisheries Science, Shanghai, China
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Harrison JW, Smith REH. Effects of ultraviolet radiation on the productivity and composition of freshwater phytoplankton communities. Photochem Photobiol Sci 2009; 8:1218-32. [PMID: 19707611 DOI: 10.1039/b902604e] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The net influence of ultraviolet radiation (UVR; 280-400 nm) on freshwater phytoplankton communities depends on the photon flux density, duration, and spectral quality of exposure and the UVR sensitivity of the assemblage in terms of photosynthetic impairment, biochemical composition, and nutrient assimilation mechanisms. Such effects are mitigated to varying degrees by photoacclimation and selective adaptation at the community level. Variation in UVR penetration among lakes is considerable, largely due to differences in chromophoric dissolved organic matter concentrations. Documented losses of areal daily primary production in lakes due to UVR range from negligible (2.5%) to appreciable (26%). UVR has the potential to alter algal biochemical composition and therefore indirectly affect higher trophic levels. There is evidence that algal nutritional status can influence UVR sensitivity, and that UVR can inhibit uptake and assimilation of inorganic nutrients, but results have been inconsistent. Taxonomic variability in susceptibility to the effects of UVR exists, and likely reflects variation in cell size and shape, concentrations of photoprotective pigments, and capacity to repair UVR photodamage. Suggestions for future research include: (1) resolution of taxon-specific UVR responses by way of single-cell techniques (e.g. enzyme-labelled fluorescence assays, microscope-based variable fluorometers) and (2) systematic comparative studies to link UVR exposure in natural habitats to community responses using the biological weighting function modelling approach. A more robust understanding of how sensitivity to UVR varies according to taxon and habitat is needed if predictions of its role in ecosystem functioning, particularly in connection with climate change, are to be meaningful.
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Affiliation(s)
- Joel W Harrison
- University of Waterloo, 200 University Avenue West, Waterloo, ON, Canada N2L3G1.
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