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Bui QTN, Pradhan B, Kim HS, Ki JS. Environmental Factors Modulate Saxitoxins (STXs) Production in Toxic Dinoflagellate Alexandrium: An Updated Review of STXs and Synthesis Gene Aspects. Toxins (Basel) 2024; 16:210. [PMID: 38787062 PMCID: PMC11125744 DOI: 10.3390/toxins16050210] [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: 02/02/2024] [Revised: 04/23/2024] [Accepted: 04/28/2024] [Indexed: 05/25/2024] Open
Abstract
The marine dinoflagellate Alexandrium is known to form harmful algal blooms (HABs) and produces saxitoxin (STX) and its derivatives (STXs) that cause paralytic shellfish poisoning (PSP) in humans. Cell growth and cellular metabolism are affected by environmental conditions, including nutrients, temperature, light, and the salinity of aquatic systems. Abiotic factors not only engage in photosynthesis, but also modulate the production of toxic secondary metabolites, such as STXs, in dinoflagellates. STXs production is influenced by a variety of abiotic factors; however, the relationship between the regulation of these abiotic variables and STXs accumulation seems not to be consistent, and sometimes it is controversial. Few studies have suggested that abiotic factors may influence toxicity and STXs-biosynthesis gene (sxt) regulation in toxic Alexandrium, particularly in A. catenella, A. minutum, and A. pacificum. Hence, in this review, we focused on STXs production in toxic Alexandrium with respect to the major abiotic factors, such as temperature, salinity, nutrients, and light intensity. This review informs future research on more sxt genes involved in STXs production in relation to the abiotic factors in toxic dinoflagellates.
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Affiliation(s)
- Quynh Thi Nhu Bui
- Department of Life Science, Sangmyung University, Seoul 03016, Republic of Korea; (Q.T.N.B.); (H.-S.K.)
| | - Biswajita Pradhan
- Department of Biotechnology, Sangmyung University, Seoul 03016, Republic of Korea;
- Department of Botany, Model Degree College, Rayagada 765017, Odisha, India
| | - Han-Sol Kim
- Department of Life Science, Sangmyung University, Seoul 03016, Republic of Korea; (Q.T.N.B.); (H.-S.K.)
| | - Jang-Seu Ki
- Department of Life Science, Sangmyung University, Seoul 03016, Republic of Korea; (Q.T.N.B.); (H.-S.K.)
- Department of Biotechnology, Sangmyung University, Seoul 03016, Republic of Korea;
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Park H, Kim HS, Abassi S, Bui QTN, Ki JS. Two novel glutathione S-transferase (GST) genes in the toxic marine dinoflagellate Alexandrium pacificum and their transcriptional responses to environmental contaminants. THE SCIENCE OF THE TOTAL ENVIRONMENT 2024; 915:169983. [PMID: 38215848 DOI: 10.1016/j.scitotenv.2024.169983] [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: 06/06/2023] [Revised: 01/02/2024] [Accepted: 01/05/2024] [Indexed: 01/14/2024]
Abstract
The present study identified two novel glutathione S-transferase (GST) genes from the toxic dinoflagellate Alexandrium pacificum and examined their molecular characteristics and transcriptional responses to algicides and environmental contaminants. Bioinformatic analysis revealed that both ApGSTs are cytosolic, belonging to the chi-like class (ApGST1) and an undefined class (ApGST2). The overall expression of ApGSTs showed similar patterns depending on the exposed contaminants, while they were differently regulated by polychlorinated biphenyl (PCB). Copper treatments (CuCl2 and CuSO4) did not significantly induce the expression of ApGSTs. The highest up-regulations of ApGST1 and ApGST2 were under 6-h treatments of 0.10 and 0.50 mg L-1 NaOCl. Interestingly, only ApGST1 increased significantly after 0.10, 0.50, and 1.00 mg L-1 of PCB exposure (6 h). Intracellular reactive oxygen species (ROS) increased considerably under NaOCl; however, it was not significantly higher in the PCB-treated cells. GST activity was increased by NaOCl and PCB treatments, but only PCB caused apoptosis. These results suggest that GSTs are involved in the first line of phase II detoxification, protecting dinoflagellate cells against oxidative damage.
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Affiliation(s)
- Hyunjun Park
- Department of Life Science, Sangmyung University, Seoul, South Korea
| | - Han-Sol Kim
- Department of Life Science, Sangmyung University, Seoul, South Korea
| | - Sofia Abassi
- Department of Life Science, Sangmyung University, Seoul, South Korea
| | - Quynh Thi Nhu Bui
- Department of Life Science, Sangmyung University, Seoul, South Korea
| | - Jang-Seu Ki
- Department of Life Science, Sangmyung University, Seoul, South Korea; Department of Biotechnology, Sangmyung University, Seoul, South Korea.
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Cooney EC, Holt CC, Jacko-Reynolds VKL, Leander BS, Keeling PJ. Photosystems in the eye-like organelles of heterotrophic warnowiid dinoflagellates. Curr Biol 2023; 33:4252-4260.e3. [PMID: 37703877 DOI: 10.1016/j.cub.2023.08.052] [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: 06/06/2023] [Revised: 08/03/2023] [Accepted: 08/16/2023] [Indexed: 09/15/2023]
Abstract
Warnowiid dinoflagellates contain a highly complex camera-eye-like structure called the ocelloid that is composed of different organelles resembling parts of metazoan eyes, including a modified plastid that serves as the retinal body.1 The overall structure of the ocelloid has been investigated by microscopy; because warnowiids are not in culture and are rare in nature, we know little about their function.1,2 Here, we generate single-cell transcriptomes from 18 warnowiid cells collected directly from the marine environment representing all 4 known genera and 1 previously undescribed genus, as well as 8 cells from a related lineage, the polykrikoids. Phylogenomic analyses show that photosynthesis was independently lost twice in warnowiids. Interestingly, the non-photosynthetic taxa still express a variety of photosynthesis-related proteins. Nematodinium and Warnowia (known or suspected to be photosynthetic1,3) unsurprisingly express a full complement of photosynthetic pathway components. However, non-photosynthetic genera with ocelloids were also found to express light-harvesting complexes, photosystem I, photosynthetic electron transport (PET), cytochrome b6f, and, in Erythropsidinium, plastid ATPase, representing all major complexes except photosystem II and the Calvin cycle. This suggests that the non-photosynthetic retinal body has retained a reduced but still substantial photosynthetic apparatus that perhaps functions using cyclic electron flow (CEF). This may support ATP synthesis in a reduced capacity, but it is also possible that the photosystem has been co-opted to function as a light-driven proton pump at the heart of the sensory mechanism within the complex architecture of ocelloids.
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Affiliation(s)
- Elizabeth C Cooney
- Department of Botany, University of British Columbia, Vancouver, BC V6T 1Z4, Canada; Hakai Institute, Heriot Bay, BC V9W 5E3, Canada.
| | - Corey C Holt
- Department of Botany, University of British Columbia, Vancouver, BC V6T 1Z4, Canada; Hakai Institute, Heriot Bay, BC V9W 5E3, Canada
| | | | - Brian S Leander
- Department of Botany, University of British Columbia, Vancouver, BC V6T 1Z4, Canada; Department of Zoology, University of British Columbia, Vancouver, BC V6T 1Z4, Canada
| | - Patrick J Keeling
- Department of Botany, University of British Columbia, Vancouver, BC V6T 1Z4, Canada
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Roussel A, Mériot V, Jauffrais T, Berteaux-Lecellier V, Lebouvier N. OMICS Approaches to Assess Dinoflagellate Responses to Chemical Stressors. BIOLOGY 2023; 12:1234. [PMID: 37759633 PMCID: PMC10525455 DOI: 10.3390/biology12091234] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/25/2023] [Revised: 07/13/2023] [Accepted: 07/18/2023] [Indexed: 09/29/2023]
Abstract
Dinoflagellates are important primary producers known to form Harmful Algae Blooms (HABs). In water, nutrient availability, pH, salinity and anthropogenic contamination constitute chemical stressors for them. The emergence of OMICs approaches propelled our understanding of dinoflagellates' responses to stressors. However, in dinoflagellates, these approaches are still biased, as transcriptomic approaches are largely conducted compared to proteomic and metabolomic approaches. Furthermore, integrated OMICs approaches are just emerging. Here, we report recent contributions of the different OMICs approaches to the investigation of dinoflagellates' responses to chemical stressors and discuss the current challenges we need to face to push studies further despite the lack of genomic resources available for dinoflagellates.
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Affiliation(s)
- Alice Roussel
- ISEA, EA7484, Campus de Nouville, Université de la Nouvelle Calédonie, Noumea 98851, New Caledonia; (A.R.); (V.M.)
| | - Vincent Mériot
- ISEA, EA7484, Campus de Nouville, Université de la Nouvelle Calédonie, Noumea 98851, New Caledonia; (A.R.); (V.M.)
- Ifremer, IRD, CNRS, Univ. de la Réunion, Univ. de la Nouvelle Calédonie, UMR 9220 ENTROPIE, 101 Promenade Roger Laroque, Noumea 98897, New Caledonia;
| | - Thierry Jauffrais
- Ifremer, IRD, CNRS, Univ. de la Réunion, Univ. de la Nouvelle Calédonie, UMR 9220 ENTROPIE, 101 Promenade Roger Laroque, Noumea 98897, New Caledonia;
| | - Véronique Berteaux-Lecellier
- CNRS, Ifremer, IRD, Univ. de la Réunion, Univ. de la Nouvelle Calédonie, UMR 9220 ENTROPIE, 101 Promenade Roger Laroque, Noumea 98897, New Caledonia;
| | - Nicolas Lebouvier
- ISEA, EA7484, Campus de Nouville, Université de la Nouvelle Calédonie, Noumea 98851, New Caledonia; (A.R.); (V.M.)
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Bui QTN, Ki JS. Two novel superoxide dismutase genes (CuZnSOD and MnSOD) in the toxic marine dinoflagellate Alexandrium pacificum and their differential responses to metal stressors. CHEMOSPHERE 2023; 313:137532. [PMID: 36509186 DOI: 10.1016/j.chemosphere.2022.137532] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/28/2022] [Revised: 12/08/2022] [Accepted: 12/09/2022] [Indexed: 06/17/2023]
Abstract
Superoxide dismutase (SOD) is an important antioxidant enzyme that is involved in the first line of defense against reactive oxygen species (ROS) within cells. Herein, we determined two novel CuZnSOD and MnSOD genes from the toxic marine dinoflagellate Alexandrium pacificum (designated as ApCuZnSOD and ApMnSOD) and characterized their structural features and phylogenetic affiliations. In addition, we examined the relative gene expression and ROS levels following exposure to heavy metals. ApCuZnSOD encoded 358 amino acids (aa) with two CuZnSOD-conserved domains. ApMnSOD encoded 203 aa that contained a mitochondrial-targeting signal and a MnSOD signature motif but missed an N-terminal domain. Phylogenetic trees showed that ApCuZnSOD clustered with other dinoflagellates, whereas ApMnSOD formed a clade with green algae and plants. Based on the 72-h median effective concentration (EC50), A. pacificum showed toxic responses in the order of Cu, Ni, Cr, Zn, Cd, and Pb. SOD expression levels dramatically increased after 6 h of Pb (≥6.5 times) and 48 h of Cu treatment (≥3.9 times). These results are consistent with the significant increase in ROS production in the A. pacificum exposed to Pb and Cu. These suggest that the two ApSODs are involved in the antioxidant defense system but respond differentially to individual metals.
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Affiliation(s)
- Quynh Thi Nhu Bui
- Department of Biotechnology, Sangmyung University, Seoul, 03016, South Korea
| | - Jang-Seu Ki
- Department of Biotechnology, Sangmyung University, Seoul, 03016, South Korea.
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Mary L, Quere J, Latimier M, Rovillon GA, Hégaret H, Réveillon D, Le Gac M. Genetic association of toxin production in the dinoflagellate Alexandrium minutum. Microb Genom 2022; 8:mgen000879. [PMID: 36326655 PMCID: PMC9836089 DOI: 10.1099/mgen.0.000879] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2022] [Accepted: 07/25/2022] [Indexed: 11/06/2022] Open
Abstract
Dinoflagellates of the genus Alexandrium are responsible for harmful algal blooms and produce paralytic shellfish toxins (PSTs). Their very large and complex genomes make it challenging to identify the genes responsible for toxin synthesis. A family-based genomic association study was developed to determine the inheritance of toxin production in Alexandrium minutum and identify genomic regions linked to this production. We show that the ability to produce toxins is inheritable in a Mendelian way, while the heritability of the toxin profile is more complex. We developed the first dinoflagellate genetic linkage map. Using this map, several major results were obtained: 1. A genomic region related to the ability to produce toxins was identified. 2. This region does not contain any polymorphic sxt genes, known to be involved in toxin production in cyanobacteria. 3. The sxt genes, known to be present in a single cluster in cyanobacteria, are scattered on different linkage groups in A. minutum. 4. The expression of two sxt genes not assigned to any linkage group, sxtI and sxtG, may be regulated by the genomic region related to the ability to produce toxins. Our results provide new insights into the organization of toxicity-related genes in A. minutum, suggesting a dissociated genetic mechanism for the production of the different analogues and the ability to produce toxins. However, most of the newly identified genes remain unannotated. This study therefore proposes new candidate genes to be further explored to understand how dinoflagellates synthesize their toxins.
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Affiliation(s)
- Lou Mary
- Ifremer, DYNECO PELAGOS, 29280 Plouzané, France
- Ifremer, PHYTOX, Laboratoire METALG, F-44000 Nantes, France
- Laboratoire des Sciences de l’Environnement Marin (LEMAR), UMR 6539 CNRS UBO IRD IFREMER - Institut Universitaire Européen de la Mer, 29280 Plouzané, France
| | | | | | | | - Hélène Hégaret
- Laboratoire des Sciences de l’Environnement Marin (LEMAR), UMR 6539 CNRS UBO IRD IFREMER - Institut Universitaire Européen de la Mer, 29280 Plouzané, France
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Nowicka B. Heavy metal-induced stress in eukaryotic algae-mechanisms of heavy metal toxicity and tolerance with particular emphasis on oxidative stress in exposed cells and the role of antioxidant response. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2022; 29:16860-16911. [PMID: 35006558 PMCID: PMC8873139 DOI: 10.1007/s11356-021-18419-w] [Citation(s) in RCA: 42] [Impact Index Per Article: 21.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/04/2021] [Accepted: 12/27/2021] [Indexed: 04/15/2023]
Abstract
Heavy metals is a collective term describing metals and metalloids with a density higher than 5 g/cm3. Some of them are essential micronutrients; others do not play a positive role in living organisms. Increased anthropogenic emissions of heavy metal ions pose a serious threat to water and land ecosystems. The mechanism of heavy metal toxicity predominantly depends on (1) their high affinity to thiol groups, (2) spatial similarity to biochemical functional groups, (3) competition with essential metal cations, (4) and induction of oxidative stress. The antioxidant response is therefore crucial for providing tolerance to heavy metal-induced stress. This review aims to summarize the knowledge of heavy metal toxicity, oxidative stress and antioxidant response in eukaryotic algae. Types of ROS, their formation sites in photosynthetic cells, and the damage they cause to the cellular components are described at the beginning. Furthermore, heavy metals are characterized in more detail, including their chemical properties, roles they play in living cells, sources of contamination, biochemical mechanisms of toxicity, and stress symptoms. The following subchapters contain the description of low-molecular-weight antioxidants and ROS-detoxifying enzymes, their properties, cellular localization, and the occurrence in algae belonging to different clades, as well as the summary of the results of the experiments concerning antioxidant response in heavy metal-treated eukaryotic algae. Other mechanisms providing tolerance to metal ions are briefly outlined at the end.
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Affiliation(s)
- Beatrycze Nowicka
- Department of Plant Physiology and Biochemistry, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, Gronostajowa 7, 30-387, Kraków, Poland.
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