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Wei N, Hu C, Dittmann E, Song L, Gan N. The biological functions of microcystins. WATER RESEARCH 2024; 262:122119. [PMID: 39059200 DOI: 10.1016/j.watres.2024.122119] [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: 05/21/2024] [Revised: 07/16/2024] [Accepted: 07/17/2024] [Indexed: 07/28/2024]
Abstract
Microcystins are potent hepatotoxins predominantly produced by bloom-forming freshwater cyanobacteria (e.g., Microcystis, Planktothrix, Dolichospermum). Microcystin biosynthesis involves large multienzyme complexes and tailoring enzymes encoded by the mcy gene cluster. Mutation, recombination, and deletion events have shaped the mcy gene cluster in the course of evolution, resulting in a large diversity of microcystin congeners and the natural coexistence of toxic and non-toxic strains. The biological functions of microcystins and their association with algal bloom formation have been extensively investigated over the past decades. This review synthesizes recent advances in decoding the biological role of microcystins in carbon/nitrogen metabolism, antioxidation, colony formation, and cell-to-cell communication. Microcystins appear to adopt multifunctional roles in cyanobacteria that reflect the adaptive plasticity of toxic cyanobacteria to changing environments.
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Affiliation(s)
- Nian Wei
- Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, China; Yangtze River Fisheries Research Institute, Chinese Academy of Fishery Sciences, Wuhan 430223, China
| | - Chenlin Hu
- College of Pharmacy, University of Houston, Houston, TX 77204, USA
| | - Elke Dittmann
- Institute of Biochemistry and Biology, University of Potsdam, 14476 Potsdam-Golm, Germany
| | - Lirong Song
- Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, China
| | - Nanqin Gan
- Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, China.
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2
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Martínez-Jerónimo F, Gonzalez-Trujillo L, Hernández-Zamora M. Continuous and Intermittent Exposure to the Toxigenic Cyanobacterium Microcystis aeruginosa Differentially Affects the Survival and Reproduction of Daphnia curvirostris. Toxins (Basel) 2024; 16:360. [PMID: 39195770 PMCID: PMC11359247 DOI: 10.3390/toxins16080360] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2024] [Revised: 07/28/2024] [Accepted: 08/12/2024] [Indexed: 08/29/2024] Open
Abstract
Anthropic eutrophication leads to water quality degradation because it may cause the development of harmful cyanobacterial blooms, affecting aquatic biota and threatening human health. Because in the natural environment zooplankters are exposed continuously or intermittently to cyanotoxins in the water or through cyanobacterial consumption, this study aimed to assess the effects of the toxigenic Microcystis aeruginosa VU-5 by different ways of exposure in Daphnia curvirostris. The acute toxicity produced by the cells, the aqueous crude extract of cells (ACE), and the cell-free culture medium (CFM) were determined. The effect on the survival and reproduction of D. curvirostris under continuous and intermittent exposure was determined during 26 d. The LC50 was 407,000 cells mL-1; exposure to the ACE and CFM produced mortality lower than 20%. Daphnia survivorship and reproduction were significantly reduced. Continuous exposure to Microcystis cells caused 100% mortality on the fourth day. Exposure during 4 and 24 h in 48 h cycles produced adult mortality, and reproduction decreased as the exposure time and the Microcystis concentrations increased. The higher toxicity of cells than the ACE could mean that the toxin's absorption is higher in the digestive tract. The temporary exposure to Microcystis cells produced irreversible damage despite the recovery periods with microalgae as food. The form and the continuity in exposure to Microcystis produced adverse effects, warning about threats to the zooplankton during HCBs.
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Affiliation(s)
- Fernando Martínez-Jerónimo
- Instituto Politécnico Nacional, Escuela Nacional de Ciencias Biológicas, Laboratorio de Hidrobiología Experimental, Carpio y Plan de Ayala s/n, Ciudad de México 11340, Mexico
| | | | - Miriam Hernández-Zamora
- Instituto Politécnico Nacional, Escuela Nacional de Ciencias Biológicas, Laboratorio de Hidrobiología Experimental, Carpio y Plan de Ayala s/n, Ciudad de México 11340, Mexico
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3
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Johnston LH, Huang Y, Bermarija TD, Rafuse C, Zamlynny L, Bruce MR, Graham C, Comeau AM, Valadez-Cano C, Lawrence JE, Beach DG, Jamieson RC. Proliferation and anatoxin production of benthic cyanobacteria associated with canine mortalities along a stream-lake continuum. THE SCIENCE OF THE TOTAL ENVIRONMENT 2024; 917:170476. [PMID: 38290679 DOI: 10.1016/j.scitotenv.2024.170476] [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: 10/16/2023] [Revised: 01/24/2024] [Accepted: 01/24/2024] [Indexed: 02/01/2024]
Abstract
Proliferations of benthic cyanobacteria are increasingly in the public eye, with rising animal deaths associated with benthic rather than planktonic blooms. In early June 2021, two dogs died after consuming material on the shore of Shubenacadie Grand Lake, Nova Scotia. Preliminary investigations indicated anatoxins produced by benthic cyanobacterial mats were responsible for the deaths. In this study, we monitored the growth of a toxic benthic cyanobacterial species (Microcoleus sp.) along a stream-lake continuum where the canine poisonings occurred. We found that the species was able to proliferate in both lentic and lotic environments, but temporal growth dynamics and the predominant sub-species were influenced by habitat type, and differed with hydrodynamic setting, nutrient and sunlight availability. Toxin concentration was greatest in cyanobacterial mats growing in the oligotrophic lakeshore environment (maximum measured total anatoxins (ATXs) >20 mg·kg-1 wet weight). This corresponded with a shift in the profile of ATX analogues, which also indicated changing sub-species dominance along the stream-lake transition.
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Affiliation(s)
- Lindsay H Johnston
- Centre for Water Resources Studies, Department of Civil & Resource Engineering, Dalhousie University, 1360 Barrington Street, Halifax, NS, Canada
| | - Yannan Huang
- Centre for Water Resources Studies, Department of Civil & Resource Engineering, Dalhousie University, 1360 Barrington Street, Halifax, NS, Canada
| | - Tessa D Bermarija
- Centre for Water Resources Studies, Department of Civil & Resource Engineering, Dalhousie University, 1360 Barrington Street, Halifax, NS, Canada
| | - Cheryl Rafuse
- Biotoxin Metrology, National Research Council Canada, 1411 Oxford St, Halifax, NS, Canada
| | - Lydia Zamlynny
- Biotoxin Metrology, National Research Council Canada, 1411 Oxford St, Halifax, NS, Canada
| | - Meghann R Bruce
- Canadian Rivers Institute, Department of Biology, University of New Brunswick, P.O. Box 4400, Fredericton, NB, Canada
| | - Catherine Graham
- Nova Scotia Department of Agriculture, Animal Health Laboratory, 65 River Rd, Bible Hill, NS, Canada
| | - André M Comeau
- Integrated Microbiome Resource (IMR), Dalhousie University, Halifax, Canada
| | - Cecilio Valadez-Cano
- Biology Department, University of New Brunswick, Fredericton, New Brunswick, Canada
| | - Janice E Lawrence
- Biology Department, University of New Brunswick, Fredericton, New Brunswick, Canada
| | - Daniel G Beach
- Centre for Water Resources Studies, Department of Civil & Resource Engineering, Dalhousie University, 1360 Barrington Street, Halifax, NS, Canada; Biotoxin Metrology, National Research Council Canada, 1411 Oxford St, Halifax, NS, Canada
| | - Rob C Jamieson
- Centre for Water Resources Studies, Department of Civil & Resource Engineering, Dalhousie University, 1360 Barrington Street, Halifax, NS, Canada.
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McDonald K, DesRochers N, Renaud JB, Sumarah MW, McMullin DR. Metabolomics Reveals Strain-Specific Cyanopeptide Profiles and Their Production Dynamics in Microcystis aeruginosa and M. flos-aquae. Toxins (Basel) 2023; 15:254. [PMID: 37104192 PMCID: PMC10147050 DOI: 10.3390/toxins15040254] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2023] [Revised: 03/21/2023] [Accepted: 03/27/2023] [Indexed: 04/03/2023] Open
Abstract
Cyanobacterial blooms that release biologically active metabolites into the environment are increasing in frequency as a result of the degradation of freshwater ecosystems globally. The microcystins are one group of cyanopeptides that are extensively studied and included in water quality risk management frameworks. Common bloom-forming cyanobacteria produce incredibly diverse mixtures of other cyanopeptides; however, data on the abundance, distribution, and biological activities of non-microcystin cyanopeptides are limited. We used non-targeted LC-MS/MS metabolomics to study the cyanopeptide profiles of five Microcystis strains: four M. aeruginosa and one M. flos-aquae. Multivariate analysis and GNPS molecular networking demonstrated that each Microcystis strain produced a unique mixture of cyanopeptides. In total, 82 cyanopeptides from the cyanopeptolin (n = 23), microviridin (n = 18), microginin (n = 12), cyanobactin (n = 14), anabaenopeptin (n = 6), aeruginosin (n = 5), and microcystin (n = 4) classes were detected. Microcystin diversity was low compared with the other detected cyanopeptide classes. Based on surveys of the literature and spectral databases, most cyanopeptides represented new structures. To identify growth conditions yielding high amounts of multiple cyanopeptide groups, we next examined strain-specific cyanopeptide co-production dynamics for four of the studied Microcystis strains. When strains were cultivated in two common Microcystis growth media (BG-11 and MA), the qualitative cyanopeptides profiles remained unchanged throughout the growth cycle. For each of the cyanopeptide groups considered, the highest relative cyanopeptide amounts were observed in the mid-exponential growth phase. The outcomes of this study will guide the cultivation of strains producing common and abundant cyanopeptides contaminating freshwater ecosystems. The synchronous production of each cyanopeptide group by Microcystis highlights the need to make more cyanopeptide reference materials available to investigate their distributions and biological functions.
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Affiliation(s)
| | - Natasha DesRochers
- London Research and Development Center, Agriculture and Agri-Food Canada, London, ON N5V 4T3, Canada
| | - Justin B. Renaud
- London Research and Development Center, Agriculture and Agri-Food Canada, London, ON N5V 4T3, Canada
| | - Mark W. Sumarah
- London Research and Development Center, Agriculture and Agri-Food Canada, London, ON N5V 4T3, Canada
| | - David R. McMullin
- Department of Chemistry, Carleton University, Ottawa, ON K1S 5B6, Canada
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Vilar MCP, da Costa Pena Rodrigues TF, da Silva Ferrão-Filho A, de Oliveira E Azevedo SMF. Grazer-Induced Chemical Defense in a Microcystin-Producing Microcystis aeruginosa (Cyanobacteria) Exposed to Daphnia gessneri Infochemicals. J Chem Ecol 2021; 47:847-858. [PMID: 34569003 DOI: 10.1007/s10886-021-01315-5] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2021] [Revised: 09/09/2021] [Accepted: 09/14/2021] [Indexed: 10/20/2022]
Abstract
Cyanobacteria are photosynthetic microorganisms that compose phytoplankton and therefore have a trophic relationship with zooplankton, which represent an important link for energy flux in aquatic food webs. Several species can form blooms and produce bioactive metabolites known as cyanotoxins. However, the ecological and adaptative role of these toxins are still under debate. Many studies have addressed the cyanotoxins' function in defense against herbivory when grazing pressure by zooplankton plays a role in phytoplankton top-down control. Thus, the present study evaluated the ecophysiological responses of the cyanobacterial strain Microcystis aeruginosa NPLJ-4 underlying the chemical induced defense against the cladoceran Daphnia gessneri. Exposure to predator infochemicals consisted of cultures established in ASM-1 medium prepared in a filtrate from a culture of adults of D. gessneri at an environmentally relevant density. Daphnia infochemicals promoted a significant increase in toxin production by M. aeruginosa. However, no differences in growth were observed, despite a significant increase in both maximum photosynthetic efficiency and electron transport rate in response to zooplankton. Additionally, there was no significant variation in the production of exopolysaccharides. Overall, although a grazer-induced defense response was demonstrated, there were no effects on M. aeruginosa fitness, which maintained its growth in the presence of Daphnia alarm cues.
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Affiliation(s)
- Mauro Cesar Palmeira Vilar
- Laboratory of Ecophysiology and Toxicology of Cyanobacteria, Carlos Chagas Filho Institute of Biophysics, Federal University of Rio de Janeiro, Rio de Janeiro, 21949-902, Brazil.
| | - Thiago Ferreira da Costa Pena Rodrigues
- Laboratory of Ecophysiology and Toxicology of Cyanobacteria, Carlos Chagas Filho Institute of Biophysics, Federal University of Rio de Janeiro, Rio de Janeiro, 21949-902, Brazil
| | - Aloysio da Silva Ferrão-Filho
- Laboratory of Evaluation and Promotion of Environmental Health, Instituto Oswaldo Cruz, FIOCRUZ, Rio de Janeiro, RJ, 21040-360, Brazil
| | - Sandra Maria Feliciano de Oliveira E Azevedo
- Laboratory of Ecophysiology and Toxicology of Cyanobacteria, Carlos Chagas Filho Institute of Biophysics, Federal University of Rio de Janeiro, Rio de Janeiro, 21949-902, Brazil
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Sukenik A, Kaplan A. Cyanobacterial Harmful Algal Blooms in Aquatic Ecosystems: A Comprehensive Outlook on Current and Emerging Mitigation and Control Approaches. Microorganisms 2021; 9:1472. [PMID: 34361909 PMCID: PMC8306311 DOI: 10.3390/microorganisms9071472] [Citation(s) in RCA: 41] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2021] [Revised: 07/04/2021] [Accepted: 07/06/2021] [Indexed: 12/31/2022] Open
Abstract
An intensification of toxic cyanobacteria blooms has occurred over the last three decades, severely affecting coastal and lake water quality in many parts of the world. Extensive research is being conducted in an attempt to gain a better understanding of the driving forces that alter the ecological balance in water bodies and of the biological role of the secondary metabolites, toxins included, produced by the cyanobacteria. In the long-term, such knowledge may help to develop the needed procedures to restore the phytoplankton community to the pre-toxic blooms era. In the short-term, the mission of the scientific community is to develop novel approaches to mitigate the blooms and thereby restore the ability of affected communities to enjoy coastal and lake waters. Here, we critically review some of the recently proposed, currently leading, and potentially emerging mitigation approaches in-lake novel methodologies and applications relevant to drinking-water treatment.
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Affiliation(s)
- Assaf Sukenik
- The Yigal Allon Kinneret Limnological Laboratory, Israel Oceanographic and Limnological Research, P.O. Box 447, Migdal 14950, Israel
| | - Aaron Kaplan
- Department of Plant and Environmental Sciences, Edmond J. Safra Campus, The Hebrew University of Jerusalem, Givat Ram, Jerusalem 9190401, Israel;
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Vilar MCP, Rodrigues TFCP, Silva LO, Pacheco ABF, Ferrão-Filho AS, Azevedo SMFO. Ecophysiological Aspects and sxt Genes Expression Underlying Induced Chemical Defense in STX-Producing Raphidiopsis raciborskii (Cyanobacteria) against the Zooplankter Daphnia gessneri. Toxins (Basel) 2021; 13:406. [PMID: 34200983 PMCID: PMC8230027 DOI: 10.3390/toxins13060406] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2021] [Revised: 05/31/2021] [Accepted: 06/02/2021] [Indexed: 11/16/2022] Open
Abstract
Cyanobacteria stand out among phytoplankton when they form massive blooms and produce toxins. Because cyanotoxin genes date to the origin of metazoans, the hypothesis that cyanotoxins function as a defense against herbivory is still debated. Although their primary cellular function might vary, these metabolites could have evolved as an anti-predator response. Here we evaluated the physiological and molecular responses of a saxitoxin-producing Raphidiopsis raciborskii to infochemicals released by the grazer Daphnia gessneri. Induced chemical defenses were evidenced in R. raciborskii as a significant increase in the transcription level of sxt genes, followed by an increase in saxitoxin content when exposed to predator cues. Moreover, cyanobacterial growth decreased, and no significant effects on photosynthesis or morphology were observed. Overall, the induced defense response was accompanied by a trade-off between toxin production and growth. These results shed light on the mechanisms underlying zooplankton-cyanobacteria interactions in aquatic food webs. The widespread occurrence of the cyanobacterium R. raciborskii in freshwater bodies has been attributed to its phenotypic plasticity. Assessing the potential of this species to thrive over interaction filters such as zooplankton grazing pressure can enhance our understanding of its adaptive success.
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Affiliation(s)
- Mauro C. P. Vilar
- Laboratory Ecophysiology and Toxicology of Cyanobacteria, Carlos Chagas Filho Institute of Biophysics, Federal University of Rio de Janeiro, Rio de Janeiro 21949-902, Brazil; (T.F.C.P.R.); (L.O.S.); (S.M.F.O.A.)
| | - Thiago F. C. P. Rodrigues
- Laboratory Ecophysiology and Toxicology of Cyanobacteria, Carlos Chagas Filho Institute of Biophysics, Federal University of Rio de Janeiro, Rio de Janeiro 21949-902, Brazil; (T.F.C.P.R.); (L.O.S.); (S.M.F.O.A.)
| | - Luan O. Silva
- Laboratory Ecophysiology and Toxicology of Cyanobacteria, Carlos Chagas Filho Institute of Biophysics, Federal University of Rio de Janeiro, Rio de Janeiro 21949-902, Brazil; (T.F.C.P.R.); (L.O.S.); (S.M.F.O.A.)
| | - Ana Beatriz F. Pacheco
- Laboratory Biological Physics, Carlos Chagas Filho Institute of Biophysics, Federal University of Rio de Janeiro, Rio de Janeiro 21949-902, Brazil;
| | - Aloysio S. Ferrão-Filho
- Laboratory of Evaluation and Promotion of Environmental Health, Instituto Oswaldo Cruz, FIOCRUZ, Rio de Janeiro 21040-360, Brazil;
| | - Sandra M. F. O. Azevedo
- Laboratory Ecophysiology and Toxicology of Cyanobacteria, Carlos Chagas Filho Institute of Biophysics, Federal University of Rio de Janeiro, Rio de Janeiro 21949-902, Brazil; (T.F.C.P.R.); (L.O.S.); (S.M.F.O.A.)
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McDonald K, Renaud JB, Pick FR, Miller JD, Sumarah MW, McMullin DR. Diagnostic Fragmentation Filtering for Cyanopeptolin Detection. ENVIRONMENTAL TOXICOLOGY AND CHEMISTRY 2021; 40:1087-1097. [PMID: 33238037 DOI: 10.1002/etc.4941] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/11/2020] [Revised: 10/25/2020] [Accepted: 11/20/2020] [Indexed: 06/11/2023]
Abstract
Cyanobacteria are ubiquitous photosynthetic prokaryotes that produce structurally diverse bioactive metabolites. Although microcystins are extensively studied, other cyanopeptides produced by common bloom-forming species have received little attention. Cyanopeptolins are a large cyanopeptide group that contain a characteristic 3-amino-6-hydroxy-2-piperidone (Ahp) moiety. In the present study we used diagnostic fragmentation filtering (DFF), a semitargeted liquid chromatography-tandem mass spectrometry (MS/MS) product ion filtering approach, to investigate cyanopeptolin diversity from 5 Microcystis strains and 4 bloom samples collected from lakes in Ontario and Quebec, Canada. Data processing by DFF was used to search MS/MS data sets for pairs of diagnostic product ions corresponding to cyanopeptolin partial sequences. For example, diagnostic product ions at m/z 150.0912 and 215.1183 identified cyanopeptolins with the NMe-Tyr-Phe-Ahp partial sequence. Forty-eight different cyanopeptolins, including 35 new variants, were detected from studied strains and bloom samples. Different cyanopeptolin profiles were identified from each sample. We detected a new compound, cyanopeptolin 1143, from a bloom and elucidated its planar structure from subsequent targeted MS/MS experiments. Diagnostic fragmentation filtering is a rapid, easy-to-perform postacquisition metabolomics strategy for inferring structural features and prioritizing new compounds for further study and dereplication. More work on cyanopeptolin occurrence and toxicity is needed because their concentrations in freshwater lakes after blooms can be similar to those of microcystins. Environ Toxicol Chem 2021;40:1087-1097. © 2020 SETAC.
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Affiliation(s)
| | - Justin B Renaud
- London Research and Development Center, Agriculture and Agri-Food Canada, London, Ontario, Canada
| | - Frances R Pick
- Department of Biology, University of Ottawa, Ottawa, Ontario, Canada
| | - J David Miller
- Department of Chemistry, Carleton University, Ottawa, Ontario, Canada
| | - Mark W Sumarah
- London Research and Development Center, Agriculture and Agri-Food Canada, London, Ontario, Canada
| | - David R McMullin
- Department of Chemistry, Carleton University, Ottawa, Ontario, Canada
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Bojadzija Savic G, Colinet H, Bormans M, Edwards C, Lawton LA, Briand E, Wiegand C. Cell free Microcystis aeruginosa spent medium affects Daphnia magna survival and stress response. Toxicon 2021; 195:37-47. [PMID: 33716069 DOI: 10.1016/j.toxicon.2021.03.009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2020] [Revised: 02/19/2021] [Accepted: 03/08/2021] [Indexed: 12/01/2022]
Abstract
Primary consumers in freshwater ecosystems, such as the zooplankton organism Daphnia magna, are highly affected by cyanobacteria, both as they may use it as a food source but also by cyanobacterial metabolites present in the water. Here, we investigate the impacts of cyanobacterial metabolites focussing on the environmental realistic scenario of the naturally released mixture without crushing cyanobacterial cells or their uptake as food. Therefore, D. magna were exposed to two concentrations of cell free cyanobacterial spent medium from Microcystis aeruginosa PCC 7806 to represent higher and lower ecologically-relevant concentrations of cyanobacterial metabolites. Including microcystin-LR, 11 metabolites have been detected of which 5 were quantified. Hypothesising concentration and time dependent negative impact, survival, gene expression marking digestion and metabolism, oxidative stress response, cell cycle and molting as well as activities of detoxification and antioxidant enzymes were followed for 7 days. D. magna suffered from oxidative stress as both catalase and glutathione S-transferase enzyme activities significantly decreased, suggesting enzyme exhaustibility after 3 and 7 days. Moreover, gene-expressions of the 4 stress markers (glutathione S-transferase, glutathione peroxidase, catalase and thioredoxin) were merely downregulated after 7 days of exposure. Energy allocation (expression of glyceraldehyde-3-phosphate dehydrogenase) was increased after 3 days but decreased as well after 7 days exposure. Cell cycle was impacted time dependently but differently by the two concentrations, along with an increasing downregulation of myosin heavy chain responsible for cell arrangement and muscular movements. Deregulation of nuclear hormone receptor genes indicate that D. magna hormonal steering including molting seemed impaired despite no detection of microviridin J in the extracts. As a consequence of all those responses and presumably of more than investigated molecular and physiological changes, D. magna survival was impaired over time, in a concentration dependent manner. Our results confirm that besides microcystin-LR, other secondary metabolites contribute to negative impact on D. magna survival and stress response.
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Affiliation(s)
| | - Hervé Colinet
- UMR ECOBIO, 6553 CNRS, Université de Rennes 1, Campus de Beaulieu, Rennes, France.
| | - Myriam Bormans
- UMR ECOBIO, 6553 CNRS, Université de Rennes 1, Campus de Beaulieu, Rennes, France.
| | - Christine Edwards
- School of Pharmacy and Life Sciences, Robert Gordon University, Aberdeen, AB10 7GJ, United Kingdom.
| | - Linda A Lawton
- School of Pharmacy and Life Sciences, Robert Gordon University, Aberdeen, AB10 7GJ, United Kingdom.
| | - Enora Briand
- IFREMER, Phycotoxins Laboratory, F-44311, Nantes, France.
| | - Claudia Wiegand
- UMR ECOBIO, 6553 CNRS, Université de Rennes 1, Campus de Beaulieu, Rennes, France.
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Rzymski P, Klimaszyk P, Jurczak T, Poniedziałek B. Oxidative Stress, Programmed Cell Death and Microcystin Release in Microcystis aeruginosa in Response to Daphnia Grazers. Front Microbiol 2020; 11:1201. [PMID: 32625177 PMCID: PMC7311652 DOI: 10.3389/fmicb.2020.01201] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2020] [Accepted: 05/12/2020] [Indexed: 01/01/2023] Open
Abstract
There is increasing evidence that programmed cell death (PCD) in cyanobacteria is triggered by oxidative stress and that it contributes to the survival of the cyanobacterial population such as Microcystis aeruginosa. At the same time, microcystins (MCs) released during cell lysis have been implicated in colony formation (enabled by the release of polysaccharides) in M. aeruginosa – a strategy that allows the effect of a stressor, including grazing to be avoided or decreased. This experimental research has explored whether extracts of Daphnia magna and Daphnia cucullata (corresponding to 5, 25, 50, and 100 individuals per liter) reveal the effect on the growth, intracellular reactive oxygen species (ROS) content, lipid peroxidation, PCD, MC-LR release, and bound exopolysaccharide (EPS) level in M. aeruginosa during 7 days of exposure. As demonstrated, extracts of both daphnids induced dose-dependent growth inhibition, increase in ROS levels, lipid peroxidation, and PCD. Moreover, the release of MC-LR and an increase in the bound EPS fraction were observed in treated cultures. Generally, the greatest effects were observed under the influence of D. magna extracts. The study indicates that grazer presence can potentially trigger a series of events in the Microcystis population, with cells undergoing oxidative stress-induced PCD associated with MC release, which in turn increases EPS production by intact cells. As argued, this strategy is likely to have evolved in response to abiotic stressors, since both PCD and synthesis of MC in cyanobacteria predate the metazoan lineage. Nevertheless, it may still provide a benefit for the survival of the MC-producing M. aeruginosa population under grazer pressure.
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Affiliation(s)
- Piotr Rzymski
- Department of Environmental Medicine, Poznan University of Medical Sciences, Poznan´, Poland
| | - Piotr Klimaszyk
- Department of Water Protection, Adam Mickiewicz University, Poznan´, Poland
| | - Tomasz Jurczak
- UNESCO Chair on Ecohydrology and Applied Ecology, University of Lodz, Łódz´, Poland
| | - Barbara Poniedziałek
- Department of Environmental Medicine, Poznan University of Medical Sciences, Poznan´, Poland
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