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Sixto M, Riobó P, Rodríguez F, Díaz PA, Figueroa RI. Climate Change Stressors, Phosphate Limitation, and High Irradiation Interact to Increase Alexandrium minutum Toxicity and Modulate Encystment Rates. Microorganisms 2024; 12:1480. [PMID: 39065248 PMCID: PMC11278771 DOI: 10.3390/microorganisms12071480] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2024] [Revised: 07/11/2024] [Accepted: 07/12/2024] [Indexed: 07/28/2024] Open
Abstract
The changes in the cell physiology (growth rate, cell size, and cell DNA content), photosynthetic efficiency, toxicity, and sexuality under variable light and nutrient (phosphates) conditions were evaluated in cultures of the dinoflagellate Alexandrium minutum obtained from a red tide in the Ría de Vigo (NW Spain). The cells were grown at low (40 and 150 µE m-2 s-1), moderate (400 µE m-2 s-1), and high (800 µE m-2 s-1) light intensities in a medium with phosphate (P+) and without (P-). Cultures were acclimated to the irradiance conditions for one week, and the experiment was run for ~1 month. The cell size and DNA content were monitored via flow cytometry. Two different clonal strains were employed as a monoculture (in a P- or P+ medium) or, to foster sexuality and resting cyst formation, as a mixed culture (only in a P- medium). A. minutum growth was favored by increasing light intensities until 400 µE m-2 s-1. The DNA content analyses indicated the accumulation of S-phase cells at the highest light intensities (400 and 800 µE m-2 s-1) and therefore the negative effects on cell cycle progression. Only when the cells were grown in a P- medium did higher light intensities trigger dose-dependent, significantly higher toxicities in all the A. minutum cultures. This result suggests that the toxicity level is responsive to the combined effects of (high) light and (low) P stress. The cell size was not significantly affected by the light intensity or P conditions. The optimal light intensity for resting cyst formation was 150 µE m-2 s-1, with higher irradiances reducing the total encystment yield. Encystment was not observed at the lowest light intensity tested, indicative of the key role of low-level irradiance in gamete and/or zygote formation, in contrast to the stressor effect of excessive irradiance on planozygote formation and/or encystment.
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Affiliation(s)
- Marta Sixto
- Centro Oceanográfico de Vigo, Instituto Español de Oceanografía (IEO-CSIC), Subida a Radio Faro 50-52, 36390 Vigo, Spain;
- Campus do Mar, Facultad de Ciencias del Mar, Universidad de Vigo, 36311 Vigo, Spain
| | - Pilar Riobó
- Instituto de Investigaciones Marinas, Consejo Superior de Investigaciones Científicas (IIM-CSIC), Eduardo Cabello 6, 36208 Vigo, Spain;
| | - Francisco Rodríguez
- Centro Oceanográfico de Vigo, Instituto Español de Oceanografía (IEO-CSIC), Subida a Radio Faro 50-52, 36390 Vigo, Spain;
| | - Patricio A. Díaz
- Centro i~mar & CeBiB, Universidad de Los Lagos, Casilla 557, Puerto Montt 5480000, Chile;
| | - Rosa I. Figueroa
- Centro Oceanográfico de Vigo, Instituto Español de Oceanografía (IEO-CSIC), Subida a Radio Faro 50-52, 36390 Vigo, Spain;
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Chen T, Zhang H, Dong W, Bu K, Chen X. Toxin production and transcriptomic response to nitrate concentrations in the toxic dinoflagellate Alexandrium tamarense. MARINE ENVIRONMENTAL RESEARCH 2024; 198:106550. [PMID: 38820827 DOI: 10.1016/j.marenvres.2024.106550] [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: 11/06/2023] [Revised: 04/22/2024] [Accepted: 05/09/2024] [Indexed: 06/02/2024]
Abstract
The bloom-forming dinoflagellate Alexandrium tamarense is one of the most important producers of paralytic shellfish poisoning toxins. Annually recurrent blooms of this dinoflagellate species is associated with the incremental nitrogen influx, especially excessive nitrate input. However, limited studies have been conducted on the toxin production and underlying molecular regulation mechanisms of A. tamarense under various nitrate (N) conditions. Therefore, toxin production and transcriptomic responses of this species were investigated. The toxin profile of A. tamarense was consistently dominated by the C2-toxins, and the cellular toxicity increased with N concentrations peaking at 9.23 ± 0.03 fmol/cell in the 883 μM N-added group. Under lower N conditions, expressions of two STX-core genes, sxtA and sxtG, were significantly down-regulated, suggesting that N regulated sxt expression and triggered responses related to toxin biosynthesis. Results of this study provided valuable insights into the ecophysiology of A. tamarense, enhancing our understanding of the occurrence of toxification events in natural environments.
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Affiliation(s)
- Tiantian Chen
- College of Environmental Science and Engineering, Ocean University of China, Qingdao, 266100, China; Key Laboratory of Marine Environment and Ecology, Ocean University of China, Qingdao, 266100, China
| | - Han Zhang
- College of Environmental Science and Engineering, Ocean University of China, Qingdao, 266100, China; Key Laboratory of Marine Environment and Ecology, Ocean University of China, Qingdao, 266100, China
| | - Wenlong Dong
- Shandong Marine Forecast and Hazard Mitigation Service, Qingdao, 266100, China
| | - Kexin Bu
- College of Environmental Science and Engineering, Ocean University of China, Qingdao, 266100, China; Key Laboratory of Marine Environment and Ecology, Ocean University of China, Qingdao, 266100, China
| | - Xi Chen
- College of Marine Life Sciences, Ocean University of China, Qingdao, 266003, China.
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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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Rahav E, Herut B. Impact of combined seawater warming and triazine-type herbicide pollution on the physiology and potential toxicity of the dinoflagellate Alexandrium minutum. MARINE POLLUTION BULLETIN 2023; 196:115612. [PMID: 37837785 DOI: 10.1016/j.marpolbul.2023.115612] [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: 08/03/2023] [Revised: 09/11/2023] [Accepted: 09/30/2023] [Indexed: 10/16/2023]
Abstract
Coastal phytoplankton communities are often exposed to multiple anthropogenic stressors simultaneously. Here, we experimentally examined how temperature increase (20-26 °C) and triazine-type herbicides pollution (500 ng terbutryn L-1), both recognized as emerging stressors, affect the abundance, physiology and selected saxitoxin gene expression in the toxic dinoflagellate Alexandrium minutum. The results show that A. minutum is more susceptible to terbutryn pollution with increasing temperatures, resulting in a significant decline in its abundance (∼80 %) and photosynthetic activity (∼40 %), while saxitoxin gene expression increased (1.5-2.5-fold). This suggests that in warming polluted coastal areas where A. minutum is often found, saxitoxin poisoning may occur even in the absence of a massive bloom. Our results recommend the development of science-based monitoring practices for algal dissolved toxins in coastal waters and estuaries, supporting environmental policies under warming and contaminated coastal regions.
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Affiliation(s)
- Eyal Rahav
- Israel Oceanographic and Limnological Research, National Institute of Oceanography, Haifa, Israel 310800.
| | - Barak Herut
- Israel Oceanographic and Limnological Research, National Institute of Oceanography, Haifa, Israel 310800
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Akbar MA, Mohd Yusof NY, Usup G, Ahmad A, Baharum SN, Bunawan H. Nutrient Deficiencies Impact on the Cellular and Metabolic Responses of Saxitoxin Producing Alexandrium minutum: A Transcriptomic Perspective. Mar Drugs 2023; 21:497. [PMID: 37755110 PMCID: PMC10532982 DOI: 10.3390/md21090497] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2023] [Revised: 07/11/2023] [Accepted: 07/12/2023] [Indexed: 09/28/2023] Open
Abstract
Dinoflagellate Alexandrium minutum Halim is commonly associated with harmful algal blooms (HABs) in tropical marine waters due to its saxitoxin production. However, limited information is available regarding the cellular and metabolic changes of A. minutum in nutrient-deficient environments. To fill this gap, our study aimed to investigate the transcriptomic responses of A. minutum under nitrogen and phosphorus deficiency. The induction of nitrogen and phosphorus deficiency resulted in the identification of 1049 and 763 differently expressed genes (DEGs), respectively. Further analysis using gene set enrichment analysis (GSEA) revealed 702 and 1251 enriched gene ontology (GO) terms associated with nitrogen and phosphorus deficiency, respectively. Our results indicate that in laboratory cultures, nitrogen deficiency primarily affects meiosis, carbohydrate catabolism, ammonium assimilation, ion homeostasis, and protein kinase activity. On the other hand, phosphorus deficiency primarily affects the carbon metabolic response, cellular ion transfer, actin-dependent cell movement, signalling pathways, and protein recycling. Our study provides valuable insights into biological processes and genes regulating A. minutum's response to nutrient deficiencies, furthering our understanding of the ecophysiological response of HABs to environmental change.
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Affiliation(s)
- Muhamad Afiq Akbar
- Department of Microbiology, Faculty of Biotechnology and Biomolecular Sciences, Universiti Putra Malaysia, Serdang 43400, Selangor, Malaysia
- Aquatic Animal Health and Therapeutics Laboratory, Institute of Bioscience, Universiti Putra Malaysia, Serdang 43400, Selangor, Malaysia
- Institute of System Biology, Universiti Kebangsaan Malaysia, Bangi 43600, Selangor, Malaysia;
| | - Nurul Yuziana Mohd Yusof
- Department of Earth Science and Environment, Faculty of Science and Technology, Universiti Kebangsaan Malaysia, Bangi 43600, Selangor, Malaysia; (N.Y.M.Y.); (G.U.)
| | - Gires Usup
- Department of Earth Science and Environment, Faculty of Science and Technology, Universiti Kebangsaan Malaysia, Bangi 43600, Selangor, Malaysia; (N.Y.M.Y.); (G.U.)
| | - Asmat Ahmad
- Department of Biological Sciences and Biotechnology, Faculty of Science and Technology, Universiti Kebangsaan Malaysia, Bangi 43600, Selangor, Malaysia;
| | - Syarul Nataqain Baharum
- Institute of System Biology, Universiti Kebangsaan Malaysia, Bangi 43600, Selangor, Malaysia;
| | - Hamidun Bunawan
- Institute of System Biology, Universiti Kebangsaan Malaysia, Bangi 43600, Selangor, Malaysia;
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Abassi S, Kim HS, Bui QTN, Ki JS. Effects of nitrate on the saxitoxins biosynthesis revealed by sxt genes in the toxic dinoflagellate Alexandrium pacificum (group IV). HARMFUL ALGAE 2023; 127:102473. [PMID: 37544673 DOI: 10.1016/j.hal.2023.102473] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/08/2023] [Revised: 06/09/2023] [Accepted: 06/10/2023] [Indexed: 08/08/2023]
Abstract
The dinoflagellate Alexandrium pacificum (group IV) is of particular interest because of its involvement in harmful algal blooms and production of saxitoxin (STX), which causes paralytic shellfish poisoning. The toxicity from STX and its analogues (STXs) is suspected to be affected by nitrogen (N) availability. However, the toxicity-associated behavior and STX-biosynthesis gene responses of the toxic A. pacificum under N fluctuations have not been sufficiently investigated. In the present study, we identified the sxtI gene involved in sxt biosynthesis pathway and evaluated the effects of nitrate (NO3-) on STXs production and the expression of four sxt core genes (sxtA4, sxtG, sxtB, and sxtI). Quantification of total STXs levels in the cultures under different NO3- regimes showed that NO3- concentration influenced STXs production. In addition, the proportion and concentration of STXs varied depending on the NO3- concentration. Core sxt transcript abundance was also influenced by available NO3- in a time-dependent manner. Expressional levels and patterns of sxtI were correlated with those of sxtA and sxtB. The relationship between the toxins and sxt responses in A. pacificum under various NO3- regimes suggests the direct involvement of N in the STXs biosynthesis pathway. Understanding this link would provide a tool to understand the toxin dynamics of dinoflagellates following N shifts in marine environments.
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Affiliation(s)
- Sofia Abassi
- Department of Biotechnology, Sangmyung University, Seoul, 03016, Republic of Korea
| | - Han-Sol Kim
- Department of Biotechnology, Sangmyung University, Seoul, 03016, Republic of Korea
| | - Quynh Thi Nhu Bui
- Department of Biotechnology, Sangmyung University, Seoul, 03016, Republic of Korea
| | - Jang-Seu Ki
- Department of Biotechnology, Sangmyung University, Seoul, 03016, Republic of Korea.
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Christou ED, Varkitzi I, Maneiro I, Zervoudaki S, Pagou K. The Influence of the Toxic Dinoflagellate Alexandrium minutum, Grown under Different N:P Ratios, on the Marine Copepod Acartia tonsa. Toxins (Basel) 2023; 15:toxins15040287. [PMID: 37104225 PMCID: PMC10144234 DOI: 10.3390/toxins15040287] [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: 03/28/2023] [Revised: 04/13/2023] [Accepted: 04/14/2023] [Indexed: 04/28/2023] Open
Abstract
HABs pose a threat to coastal ecosystems, the economic sector and human health, and are expanding globally. However, their influence on copepods, a major connector between primary producers and upper trophic levels, remains essentially unknown. Microalgal toxins can eventually control copepod survival and reproduction by deterring grazing and hence reducing food availability. We present several 24-h experiments in which the globally distributed marine copepod, Acartia tonsa, was exposed to different concentrations of the toxic dinoflagellate, Alexandrium minutum, grown under three N:P ratios (4:1, 16:1 and 80:1), with the simultaneous presence of non-toxic food (the dinoflagellate Prorocentrum micans). The different N:P ratios did not affect the toxicity of A. minutum, probably due to the low toxicity of the tested strain. Production of eggs and pellets as well as ingested carbon appeared to be affected by food toxicity. Toxicity levels in A. minutum also had an effect on hatching success and on the toxin excreted in pellets. Overall, A. minutum toxicity affected the reproduction, toxin excretion and, to an extent, the feeding behavior of A. tonsa. This work indicates that even short-term exposure to toxic A. minutum can impact the vital functions of A. tonsa and might ultimately pose serious threats to copepod recruitment and survival. Still, further investigation is required for identifying and understanding, in particular, the long-term effects of harmful microalgae on marine copepods.
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Affiliation(s)
- Epaminondas D Christou
- Hellenic Centre for Marine Research (HCMR), Institute of Oceanography, P.O. Box 712, 19013 Athens, Greece
| | - Ioanna Varkitzi
- Hellenic Centre for Marine Research (HCMR), Institute of Oceanography, P.O. Box 712, 19013 Athens, Greece
| | - Isabel Maneiro
- Istituti di Ricerca per l'Ambiente Marino, Consiglio Nazionale delle Ricerche (IAS CNR), SS di Capo Granitola, Via del Mare 3, Torretta Granitola, 91021 Campobello di Mazara, Italy
| | - Soultana Zervoudaki
- Hellenic Centre for Marine Research (HCMR), Institute of Oceanography, P.O. Box 712, 19013 Athens, Greece
| | - Kalliopi Pagou
- Hellenic Centre for Marine Research (HCMR), Institute of Oceanography, P.O. Box 712, 19013 Athens, Greece
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Kim HS, Park H, Wang H, Kim T, Ki JS. Saxitoxins-producing potential of the marine dinoflagellate Alexandrium affine and its environmental implications revealed by toxins and transcriptome profiling. MARINE ENVIRONMENTAL RESEARCH 2023; 185:105874. [PMID: 36689843 DOI: 10.1016/j.marenvres.2023.105874] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/11/2022] [Revised: 12/08/2022] [Accepted: 01/04/2023] [Indexed: 06/17/2023]
Abstract
The marine dinoflagellate Alexandrium occurs widely in coastal waters, and some of them can produce saxitoxins (STXs) that cause paralytic shellfish poisoning (PSP). Alexandrium affine is a harmful algal bloom (HAB)-forming species off the coast of Asia; however, its ability to produce STXs has been controversial. In the present study, we detected STXs in A. affine Alex02 isolated from the southern coast of Korea. The total STXs equivalent (STXs eq) and profiles of Alex02 varied depending on the tested environmental conditions, including the temperature and nitrate concentrations. STXs toxicity levels of A. affine Alex02 (<0.8 STXs eq fmol cell-1) were significantly lower than those of toxic A. catenella Alex03 and A. pacificum Alex05. On a genetic basis, we identified all the STX biosynthesis sxt genes, except sxtX in A. affine, via large-scale transcriptome analysis. Interestingly, the two proteins, sxtA4 and sxtG, were similar in sequence and domain structure to those of other toxic dinoflagellates and cyanobacteria; however, their transcript levels were extremely low. Our results suggest that A. affine has the potential to produce STXs, while its toxicity is much lower or negligible, which is unlikely to cause PSP incidents in marine environments.
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Affiliation(s)
- Han-Sol Kim
- Department of Biotechnology, Sangmyung University, Seoul, 03016, South Korea
| | - Hyunjun Park
- Department of Biotechnology, Sangmyung University, Seoul, 03016, South Korea
| | - Hui Wang
- Department of Biotechnology, Sangmyung University, Seoul, 03016, South Korea
| | - Taehee Kim
- 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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Wan X, Yao G, Wang K, Bao S, Han P, Wang F, Song T, Jiang H. Transcriptomic analysis of polyketide synthesis in dinoflagellate, Prorocentrum lima. HARMFUL ALGAE 2023; 123:102391. [PMID: 36894212 DOI: 10.1016/j.hal.2023.102391] [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: 08/30/2022] [Revised: 12/31/2022] [Accepted: 01/31/2023] [Indexed: 06/18/2023]
Abstract
The benthic dinoflagellate Prorocentrum lima is among the most common toxic morphospecies with a cosmopolitan distribution. P. lima can produce polyketide compounds, such as okadaic acid (OA), dinophysistoxin (DTX) and their analogues, which are responsible for diarrhetic shellfish poisoning (DSP). Studying the molecular mechanism of DSP toxin biosynthesis is crucial for understanding the environmental driver influencing toxin biosynthesis as well as for better monitoring of marine ecosystems. Commonly, polyketides are produced by polyketide synthases (PKS). However, no gene has been confirmatively assigned to DSP toxin production. Here, we assembled a transcriptome from 94,730,858 Illumina RNAseq reads using Trinity, resulting in 147,527 unigenes with average sequence length of 1035 nt. Using bioinformatics analysis methods, we found 210 unigenes encoding single-domain PKS with sequence similarity to type I PKSs, as reported in other dinoflagellates. In addition, 15 transcripts encoding multi-domain PKS (forming typical type I PKSs modules) and 5 transcripts encoding hybrid nonribosomal peptide synthetase (NRPS)/PKS were found. Using comparative transcriptome and differential expression analysis, a total of 16 PKS genes were identified to be up-regulated in phosphorus-limited cultures, which was related to the up regulation of toxin expression. In concert with other recent transcriptome analyses, this study contributes to the building consensus that dinoflagellates may utilize a combination of Type I multi-domain and single-domain PKS proteins, in an as yet undefined manner, to synthesize polyketides. Our study provides valuable genomic resource for future research in order to understand the complex mechanism of toxin production in this dinoflagellate.
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Affiliation(s)
- Xiukun Wan
- State Key Laboratory of NBC Protection for Civilian, Beijing 102205, China
| | - Ge Yao
- State Key Laboratory of NBC Protection for Civilian, Beijing 102205, China
| | - Kang Wang
- State Key Laboratory of NBC Protection for Civilian, Beijing 102205, China
| | - Shaoheng Bao
- State Key Laboratory of NBC Protection for Civilian, Beijing 102205, China
| | - Penggang Han
- State Key Laboratory of NBC Protection for Civilian, Beijing 102205, China
| | - Fuli Wang
- State Key Laboratory of NBC Protection for Civilian, Beijing 102205, China
| | - Tianyu Song
- State Key Laboratory of NBC Protection for Civilian, Beijing 102205, China
| | - Hui Jiang
- State Key Laboratory of NBC Protection for Civilian, Beijing 102205, China.
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Cho Y, Tsuchiya S, Omura T, Koike K, Konoki K, Oshima Y, Yotsu-Yamashita M. Metabolic inhibitor induces dynamic changes in saxitoxin biosynthesis and metabolism in the dinoflagellate Alexandrium pacificum (Group IV) under in vivo labeling condition. HARMFUL ALGAE 2023; 122:102372. [PMID: 36754461 DOI: 10.1016/j.hal.2022.102372] [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: 09/04/2022] [Revised: 12/14/2022] [Accepted: 12/19/2022] [Indexed: 06/18/2023]
Abstract
In paralytic shellfish toxin-producing dinoflagellates, intracellular levels of saxitoxin and its analogues (STXs) are controlled by a balance between degradation and biosynthesis in response to marine environmental fluctuations and stresses. The purpose of this study was to demonstrate the utility of statistical analysis of in vivo labeling data for the dynamic analysis of variations in toxin production under stress. A toxic strain of the dinoflagellate Alexandrium pacificum (Group IV) was cultured in colchicine-containing 15N-labeled sodium nitrate-medium and metabolite levels were analyzed over time by liquid chromatography-mass spectrometry. Quantitative values of all isotopomers of precursor amino acids, biosynthetic intermediates, and major STXs were subjected to statistical analysis. The decrease of the nitrogen incorporation rates for all compounds suggested that colchicine decreased nitrate assimilation upstream of glutamate biosynthesis. In colchicine-treated cultures, the per-cell content of total STX analogues did not change significantly over time; however, the production rate of each pathway varied greatly. De novo STX biosynthesis was decreased by colchicine until Day 3, while the salvage pathway was not. Subsequently, biosynthesis by both pathways was enhanced. This analysis of dynamic metabolism provides new insights into the complex mechanisms regulating STX metabolism in dinoflagellates.
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Affiliation(s)
- Yuko Cho
- Graduate School of Agricultural Science, Tohoku University, 468-1 Aramaki-Aza-Aoba, Aoba-ku, Sendai, Miyagi 980-8572, Japan.
| | - Shigeki Tsuchiya
- Graduate School of Agricultural Science, Tohoku University, 468-1 Aramaki-Aza-Aoba, Aoba-ku, Sendai, Miyagi 980-8572, Japan
| | - Takuo Omura
- Laboratory of Aquatic Science Consultant Co., LTD. 2-30-17, Higashikamata, Ota-ku, Tokyo 144-0031, Japan
| | - Kazuhiko Koike
- Graduate School of Integrated Sciences for Life, Hiroshima University, 1-4-4 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8528, Japan
| | - Keiichi Konoki
- Graduate School of Agricultural Science, Tohoku University, 468-1 Aramaki-Aza-Aoba, Aoba-ku, Sendai, Miyagi 980-8572, Japan
| | - Yasukatsu Oshima
- Graduate School of Life Sciences, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai, Miyagi 980-8577, Japan
| | - Mari Yotsu-Yamashita
- Graduate School of Agricultural Science, Tohoku University, 468-1 Aramaki-Aza-Aoba, Aoba-ku, Sendai, Miyagi 980-8572, Japan
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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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Lian Z, Li F, He X, Chen J, Yu RC. Rising CO 2 will increase toxicity of marine dinoflagellate Alexandrium minutum. JOURNAL OF HAZARDOUS MATERIALS 2022; 431:128627. [PMID: 35359114 DOI: 10.1016/j.jhazmat.2022.128627] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/13/2022] [Revised: 03/01/2022] [Accepted: 03/02/2022] [Indexed: 06/14/2023]
Abstract
Ocean acidification caused by increasing emission of carbon dioxide (CO2) is expected to have profound impacts on marine ecological processes, including the formation and evolution of harmful algal blooms (HABs). We designed a set of experiments in the laboratory to examine the effects of increasing CO2 on the growth and toxicity of a toxic dinoflagellate Alexandrium minutum producing paralytic shellfish toxins (PSTs). It was found that high levels of CO2 (800 and 1200 ppm) significantly promoted the growth of A. minutum compared to the group (400 ppm) representing the current CO2 level. The total yields of PSTs by A. minutum, including both intracellular and extracellular toxins, were significantly enhanced, probably due to the induction of core enzyme activity and key amino acids synthesis for PST production. More interestingly, high level of CO2 promoted the transformation from gonyautoxin2&3 to gonyautoxin1&4 and depressed the release of PSTs from inside to outside of the cells. All these processes collectively led to an apparent increase of A. minutum toxicity. Our study demonstrated that rising CO2 would increase the risk of toxic A. minutum based on the comprehensive analyses of different processes including algal growth and toxin synthesis, transformation and release.
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Affiliation(s)
- Ziru Lian
- Marine College, Shandong University, Weihai 264209, PR China.
| | - Fang Li
- Marine College, Shandong University, Weihai 264209, PR China; Marine Bioresource and Environment Research Center, Key Laboratory of Marine Eco-Environmental Science and Technology, The First Institute of Oceanography, Ministry of Natural Resources, Qingdao 266061, PR China
| | - Xiuping He
- Marine Bioresource and Environment Research Center, Key Laboratory of Marine Eco-Environmental Science and Technology, The First Institute of Oceanography, Ministry of Natural Resources, Qingdao 266061, PR China
| | - Junhui Chen
- Marine Bioresource and Environment Research Center, Key Laboratory of Marine Eco-Environmental Science and Technology, The First Institute of Oceanography, Ministry of Natural Resources, Qingdao 266061, PR China
| | - Ren-Cheng Yu
- CAS Key Laboratory of Marine Ecology and Environmental Sciences, Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, PR China; University of Chinese Academy of Sciences, Beijing 100049, PR China
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13
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Thi Nhu Bui Q, Kim H, Wang H, Ki JS. Unveiling the genomic structures and evolutionary events of the saxitoxin biosynthetic gene sxtA in the marine toxic dinoflagellate Alexandrium. Mol Phylogenet Evol 2022; 168:107417. [PMID: 35031458 DOI: 10.1016/j.ympev.2022.107417] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2021] [Revised: 11/24/2021] [Accepted: 12/27/2021] [Indexed: 12/30/2022]
Abstract
Marine dinoflagellates Alexandriumare known to produce saxitoxin (STX) and cause paralytic shellfish poisoning (PSP) which can result in mortality in human. SxtA is considered a core gene for the biosynthesis of STX. However, its gene coding structure and evolutionary history have yet to be fully elucidated. Here, we determined the full-length sequences of sxtA cDNA and genomic coding regions from two toxic dinoflagellates, Alexandrium catenella (LIMS-PS-2645 and LIMS-PS-2647) andA. pacificum (LMBE-C4), characterised their domain structures, and resolved evolutionary events. The sxtA gene was encoded on the genome without introns, and was identical in length (4002 bp) between two A. catenella strains, but their sequences differed from A. pacificum (5031 bp). SxtA consists of four domains, sxtA1, sxtA2, sxtA3, and sxtA4; however, A. pacificum has an extra domain TauD near sxtA1. Each domain had >64.4% GC content, with the highest being 71.6% in sxtA3. Molecular divergence was found to be significantly higher in sxtA4 than in the other domains. Phylogenetic trees of sxtA and separate domains showed that bacteria diverged earliest, followed by non-toxic, toxic cyanobacteria, toxic dinoflagellates. While sxtA domains in Alexandrium were similar to the PKS-like structure with the conserved sxtA1, sxtA2, and sxtA3. PKS_KS may be replaced by sxtA4 in toxic Alexandrium. These suggest that sxtA in Alexandrium may have evolved by acquiring specific domains, whose modification and complexity markedly affect toxin biosynthesis.
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Affiliation(s)
- Quynh Thi Nhu Bui
- Department of Biotechnology, Sangmyung University, Seoul 03016, South Korea
| | - Hansol Kim
- Department of Biotechnology, Sangmyung University, Seoul 03016, South Korea
| | - Hui Wang
- Department of Biotechnology, Sangmyung University, Seoul 03016, South Korea; Hunan Province Key Laboratory of Typical Environmental Pollution and Health Hazards, School of Public Health, University of South China, Hengyang 421001, China
| | - Jang-Seu Ki
- Department of Biotechnology, Sangmyung University, Seoul 03016, South Korea.
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14
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Bui QTN, Kim H, Park H, Ki JS. Salinity Affects Saxitoxins (STXs) Toxicity in the Dinoflagellate Alexandrium pacificum, with Low Transcription of SXT-Biosynthesis Genes sxtA4 and sxtG. Toxins (Basel) 2021; 13:toxins13100733. [PMID: 34679026 PMCID: PMC8539879 DOI: 10.3390/toxins13100733] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2021] [Revised: 10/13/2021] [Accepted: 10/15/2021] [Indexed: 01/23/2023] Open
Abstract
Salinity is an important factor for regulating metabolic processes in aquatic organisms; however, its effects on toxicity and STX biosynthesis gene responses in dinoflagellates require further elucidation. Herein, we evaluated the physiological responses, toxin production, and expression levels of two STX synthesis core genes, sxtA4 and sxtG, in the dinoflagellate Alexandrium pacificum Alex05 under different salinities (20, 25, 30, 35, and 40 psu). Optimal growth was observed at 30 psu (0.12 cell division/d), but cell growth significantly decreased at 20 psu and was irregular at 25 and 40 psu. The cell size increased at lower salinities, with the highest size of 31.5 µm at 20 psu. STXs eq was highest (35.8 fmol/cell) in the exponential phase at 30 psu. GTX4 and C2 were predominant at that time but were replaced by GTX1 and NeoSTX in the stationary phase. However, sxtA4 and sxtG mRNAs were induced, and their patterns were similar in all tested conditions. PCA showed that gene transcriptional levels were not correlated with toxin contents and salinity. These results suggest that A. pacificum may produce the highest amount of toxins at optimal salinity, but sxtA4 and sxtG may be only minimally affected by salinity, even under high salinity stress.
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Affiliation(s)
- Quynh Thi Nhu Bui
- Department of Biotechnology, Sangmyung University, Seoul 03016, Korea
| | - Hansol Kim
- Department of Biotechnology, Sangmyung University, Seoul 03016, Korea
| | - Hyunjun Park
- Department of Biotechnology, Sangmyung University, Seoul 03016, Korea
| | - Jang-Seu Ki
- Department of Biotechnology, Sangmyung University, Seoul 03016, Korea
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15
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Hii KS, Mohd-Din M, Luo Z, Tan SN, Lim ZF, Lee LK, Leong SCY, Teng ST, Gu H, Cao X, Lim PT, Leaw CP. Diverse harmful microalgal community assemblages in the Johor Strait and the environmental effects on its community dynamics. HARMFUL ALGAE 2021; 107:102077. [PMID: 34456026 DOI: 10.1016/j.hal.2021.102077] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/05/2021] [Revised: 06/15/2021] [Accepted: 06/27/2021] [Indexed: 06/13/2023]
Abstract
Coastal ecosystems are often subjected to anthropogenic disturbances that lead to water quality deterioration and an increase in harmful algal bloom (HAB) events. Using the next-generation molecular tool of 18S rDNA metabarcoding, we examined the community assemblages of HAB species in the Johor Strait, Malaysia between May 2018 and September 2019, covering 19 stations across the strait. The molecular operational taxonomic units (OTUs) of HAB taxa retrieved from the dataset (n = 194) revealed a much higher number of HAB taxa (26 OTUs) than before, with 12 taxa belong to new records in the strait. As revealed in the findings of this study, the diversity and community structure of HAB taxa varied significantly over time and space. The most common and abundant HAB taxa in the strait (frequency of occurrence >70%) comprised Heterosigma akashiwo, Fibrocapsa japonica, Pseudo-nitzschia pungens, Dinophysis spp., Gymnodinium catenatum, Alexandrium leei, and A. tamiyavanichii. Also, our results demonstrated that the HAB community assemblages in the strait were dependent on the interplay of environmental variables that influence by the monsoonal effects. Different HAB taxa, constitute various functional types, occupied and prevailed in different environmental niches across space and time, leading to diverse community assemblages and population density. This study adds to the current understandings of HAB dynamics and provides a robust overview of temporal-spatial changes in HAB community assemblages along the environmental gradients in a tropical eutrophic coastal ecosystem.
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Affiliation(s)
- Kieng Soon Hii
- Bachok Marine Research Station, Institute of Ocean and Earth Sciences, University of Malaya, 16310 Bachok, Kelantan, Malaysia
| | - Monaliza Mohd-Din
- Bachok Marine Research Station, Institute of Ocean and Earth Sciences, University of Malaya, 16310 Bachok, Kelantan, Malaysia; Department of Biosciences, Faculty of Science, Universiti Teknologi Malaysia, 81310 Skudai, Johor, Malaysia
| | - Zhaohe Luo
- Third Institute of Oceanography, Ministry of Natural Resources, Xiamen, 361005, China
| | - Suh Nih Tan
- Bachok Marine Research Station, Institute of Ocean and Earth Sciences, University of Malaya, 16310 Bachok, Kelantan, Malaysia
| | - Zhen Fei Lim
- Bachok Marine Research Station, Institute of Ocean and Earth Sciences, University of Malaya, 16310 Bachok, Kelantan, Malaysia
| | - Li Keat Lee
- Bachok Marine Research Station, Institute of Ocean and Earth Sciences, University of Malaya, 16310 Bachok, Kelantan, Malaysia
| | - Sandric Chee Yew Leong
- Tropical Marine Science Institute, National University of Singapore, 18 Kent Ridge Road, S2S Building, Singapore, 119227 Singapore
| | - Sing Tung Teng
- Faculty of Resource Science and Technology, Universiti Malaysia Sarawak, 94300 Kota Samarahan, Sarawak, Malaysia
| | - Haifeng Gu
- Third Institute of Oceanography, Ministry of Natural Resources, Xiamen, 361005, China
| | - Xiuyun Cao
- Institute of Hydrobiologia, Chinese Academic of Science, Wuhan, China
| | - Po Teen Lim
- Bachok Marine Research Station, Institute of Ocean and Earth Sciences, University of Malaya, 16310 Bachok, Kelantan, Malaysia.
| | - Chui Pin Leaw
- Bachok Marine Research Station, Institute of Ocean and Earth Sciences, University of Malaya, 16310 Bachok, Kelantan, Malaysia.
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16
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Kim H, Park H, Wang H, Yoo HY, Park J, Ki JS. Low Temperature and Cold Stress Significantly Increase Saxitoxins (STXs) and Expression of STX Biosynthesis Genes sxtA4 and sxtG in the Dinoflagellate Alexandrium catenella. Mar Drugs 2021; 19:291. [PMID: 34064031 PMCID: PMC8224010 DOI: 10.3390/md19060291] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2021] [Revised: 05/18/2021] [Accepted: 05/18/2021] [Indexed: 12/22/2022] Open
Abstract
Toxic dinoflagellate Alexandrium spp. produce saxitoxins (STXs), whose biosynthesis pathway is affected by temperature. However, the link between the regulation of the relevant genes and STXs' accumulation and temperature is insufficiently understood. In the present study, we evaluated the effects of temperature on cellular STXs and the expression of two core STX biosynthesis genes (sxtA4 and sxtG) in the toxic dinoflagellate Alexandrium catenella Alex03 isolated from Korean waters. We analyzed the growth rate, toxin profiles, and gene responses in cells exposed to different temperatures, including long-term adaptation (12, 16, and 20 °C) and cold and heat stresses. Temperature significantly affected the growth of A. catenella, with optimal growth (0.49 division/day) at 16 °C and the largest cell size (30.5 µm) at 12 °C. High concentration of STXs eq were detected in cells cultured at 16 °C (86.3 fmol/cell) and exposed to cold stress at 20→12 °C (96.6 fmol/cell) compared to those at 20 °C and exposed to heat stress. Quantitative real-time PCR (qRT-PCR) revealed significant gene expression changes of sxtA4 in cells cultured at 16 °C (1.8-fold) and cold shock at 20→16 °C (9.9-fold). In addition, sxtG was significantly induced in cells exposed to cold shocks (20→16 °C; 19.5-fold) and heat stress (12→20 °C; 25.6-fold). Principal component analysis (PCA) revealed that low temperature (12 and 16 °C) and cold stress were positively related with STXs' production and gene expression levels. These results suggest that temperature may affect the toxicity and regulation of STX biosynthesis genes in dinoflagellates.
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Affiliation(s)
- Hansol Kim
- Department of Biotechnology, Sangmyung University, Seoul 03016, Korea; (H.K.); (H.P.); (H.W.); (H.Y.Y.)
| | - Hyunjun Park
- Department of Biotechnology, Sangmyung University, Seoul 03016, Korea; (H.K.); (H.P.); (H.W.); (H.Y.Y.)
| | - Hui Wang
- Department of Biotechnology, Sangmyung University, Seoul 03016, Korea; (H.K.); (H.P.); (H.W.); (H.Y.Y.)
| | - Hah Young Yoo
- Department of Biotechnology, Sangmyung University, Seoul 03016, Korea; (H.K.); (H.P.); (H.W.); (H.Y.Y.)
| | - Jaeyeon Park
- Environment and Resource Convergence Center, Advanced Institute of Convergence Technologies, Suwon 16229, Korea
| | - Jang-Seu Ki
- Department of Biotechnology, Sangmyung University, Seoul 03016, Korea; (H.K.); (H.P.); (H.W.); (H.Y.Y.)
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17
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Geffroy S, Lechat MM, Le Gac M, Rovillon GA, Marie D, Bigeard E, Malo F, Amzil Z, Guillou L, Caruana AMN. From the sxtA4 Gene to Saxitoxin Production: What Controls the Variability Among Alexandrium minutum and Alexandrium pacificum Strains? Front Microbiol 2021; 12:613199. [PMID: 33717003 PMCID: PMC7944994 DOI: 10.3389/fmicb.2021.613199] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2020] [Accepted: 02/03/2021] [Indexed: 12/22/2022] Open
Abstract
Paralytic shellfish poisoning (PSP) is a human foodborne syndrome caused by the consumption of shellfish that accumulate paralytic shellfish toxins (PSTs, saxitoxin group). In PST-producing dinoflagellates such as Alexandrium spp., toxin synthesis is encoded in the nuclear genome via a gene cluster (sxt). Toxin production is supposedly associated with the presence of a 4th domain in the sxtA gene (sxtA4), one of the core genes of the PST gene cluster. It is postulated that gene expression in dinoflagellates is partially constitutive, with both transcriptional and post-transcriptional processes potentially co-occurring. Therefore, gene structure and expression mode are two important features to explore in order to fully understand toxin production processes in dinoflagellates. In this study, we determined the intracellular toxin contents of twenty European Alexandrium minutum and Alexandrium pacificum strains that we compared with their genome size and sxtA4 gene copy numbers. We observed a significant correlation between the sxtA4 gene copy number and toxin content, as well as a moderate positive correlation between the sxtA4 gene copy number and genome size. The 18 toxic strains had several sxtA4 gene copies (9-187), whereas only one copy was found in the two observed non-toxin producing strains. Exploration of allelic frequencies and expression of sxtA4 mRNA in 11 A. minutum strains showed both a differential expression and specific allelic forms in the non-toxic strains compared with the toxic ones. Also, the toxic strains exhibited a polymorphic sxtA4 mRNA sequence between strains and between gene copies within strains. Finally, our study supported the hypothesis of a genetic determinism of toxin synthesis (i.e., the existence of several genetic isoforms of the sxtA4 gene and their copy numbers), and was also consistent with the hypothesis that constitutive gene expression and moderation by transcriptional and post-transcriptional regulation mechanisms are the cause of the observed variability in the production of toxins by A. minutum.
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Affiliation(s)
| | | | | | | | - Dominique Marie
- Sorbonne Université, CNRS, UMR 7144 Adaptation et Diversité en Milieu Marin, Station Biologique de Roscoff, Roscoff, France
| | - Estelle Bigeard
- Sorbonne Université, CNRS, UMR 7144 Adaptation et Diversité en Milieu Marin, Station Biologique de Roscoff, Roscoff, France
| | | | | | - Laure Guillou
- Sorbonne Université, CNRS, UMR 7144 Adaptation et Diversité en Milieu Marin, Station Biologique de Roscoff, Roscoff, France
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18
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Baek SH, Choi JM, Lee M, Park BS, Zhang Y, Arakawa O, Takatani T, Jeon JK, Kim YO. Change in Paralytic Shellfish Toxins in the Mussel Mytilus galloprovincialis Depending on Dynamics of Harmful Alexandrium catenella (Group I) in the Geoje Coast (South Korea) during Bloom Season. Toxins (Basel) 2020; 12:toxins12070442. [PMID: 32645973 PMCID: PMC7404969 DOI: 10.3390/toxins12070442] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2020] [Revised: 06/26/2020] [Accepted: 07/02/2020] [Indexed: 11/16/2022] Open
Abstract
Paralytic shellfish toxins (PSTs) produced by Alexandriumcatenella (formerly A. tamarense) in Korean coastal waters caused the deaths of four people (in 1986 and 1996) who consumed contaminated mussels (Mytilus edulis). This led to more detailed consideration of the risks of PST outbreaks and incidents in Korea, including the introduction of shellfish collection bans. In this study, we investigated the relationships between A. catenella population dynamics and PST accumulation in the mussel M. galloprovincialis. Discharges from the Nakdong River affect the environmental conditions along the Geoje coast, resulting in low salinity and high nutrient levels that trigger blooms of A. catenella. At the toxin peak on 24 April 2017, the toxins detected in A. catenella cells were C1, gonyautoxin (GTX)1 and GTX2, whereas the concentrations of PSTs in M. galloprovincialis were high and in the order of GTX4 > GTX1 > GTX3 > saxitoxin (STX) > GTX2 > neoSTX > decarbamoylgonyautoxin (dcGTX)2 > dc GTX3. The PST level in mussels was also high. At 15 °C, the PSTs are constantly found to be higher (10-fold higher in 2017 and 30-fold higher in 2018) than safe levels for human consumption (80 μg STX diHCl equivalents 100 g−1).
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Affiliation(s)
- Seung Ho Baek
- Risk Assessment Research Center, KIOST (Korea Institute of Ocean Science and Technology), Geoje 53201, Korea; (S.H.B.); (M.L.)
| | - Jung Min Choi
- Marine Ecosystem Research Center, KIOST, Busan 49111, Korea; (J.M.C.); (B.S.P.)
| | - Minji Lee
- Risk Assessment Research Center, KIOST (Korea Institute of Ocean Science and Technology), Geoje 53201, Korea; (S.H.B.); (M.L.)
| | - Bum Soo Park
- Marine Ecosystem Research Center, KIOST, Busan 49111, Korea; (J.M.C.); (B.S.P.)
| | - Yuchengmin Zhang
- Graduate School of Fisheries and Environmental Sciences, Nagasaki University, Nagasaki 852-8521, Japan; (Y.Z.); (O.A.); (T.T.)
| | - Osamu Arakawa
- Graduate School of Fisheries and Environmental Sciences, Nagasaki University, Nagasaki 852-8521, Japan; (Y.Z.); (O.A.); (T.T.)
| | - Tomohiro Takatani
- Graduate School of Fisheries and Environmental Sciences, Nagasaki University, Nagasaki 852-8521, Japan; (Y.Z.); (O.A.); (T.T.)
| | - Joong-Kyun Jeon
- Faculty of Marine Bioscience and Technology, Gangneung-Wonju National University, Gangneung 26403, Korea;
| | - Young Ok Kim
- Marine Environmental & Climate Research Division, KIOST, Busan 49111, Korea
- Correspondence: ; Tel.: +82-51-644-3240; Fax: +82-51-955-3981
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19
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Biocompatibility of Alexandrium minutum in the growth and paralytic shellfish toxins production under five cultivation methods. Toxicon 2020; 182:59-65. [DOI: 10.1016/j.toxicon.2020.05.005] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2019] [Revised: 04/26/2020] [Accepted: 05/15/2020] [Indexed: 12/31/2022]
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20
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Wu Z, Luo H, Yu L, Lee WH, Li L, Mak YL, Lin S, Lam PKS. Characterizing ciguatoxin (CTX)- and Non-CTX-producing strains of Gambierdiscus balechii using comparative transcriptomics. THE SCIENCE OF THE TOTAL ENVIRONMENT 2020; 717:137184. [PMID: 32084685 DOI: 10.1016/j.scitotenv.2020.137184] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/30/2019] [Revised: 01/28/2020] [Accepted: 02/06/2020] [Indexed: 06/10/2023]
Abstract
Gambierdiscus spp. can produce the polyketide compound, ciguatoxin (CTX), and are hence responsible for ciguatera fish poisoning (CFP). Studying the molecular mechanism that regulates CTX production is crucial for understanding the environmental trigger of CTX as well as for better informing fishery management. Commonly, polyketide synthases are important for polyketide synthesis; however, no gene has been confirmatively assigned to CTX production. Here, suppression subtractive hybridization (SSH) and transcriptome sequencing (RNA-Seq) were used to compare a CTX-producing strain with a non-CTX-producing strain. Using both methods, a total of 52 polyketide synthase (PKS) genes were identified to be up-regulated in the CTX-producing G. balechii, including transcripts encoding single-domain PKSs as well as transcripts encoding multi-domain PKSs. Using reverse transcription quantitative PCR, the expression of these genes in the CTX-producing strain and in nitrogen-limited cultures of the strain was further documented. These data suggest that PKSs are likely involved in polyketide synthesis and potentially in CTX synthesis in this dinoflagellate species. Our study provides the candidate biomarkers for the detection of CTXs or CFP in waters or any other organisms as well as a valuable genomic resource for the research on Gambierdiscus and other dinoflagellates.
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Affiliation(s)
- Zhen Wu
- State Key Laboratory of Marine Pollution, City University of Hong Kong, Hong Kong, China; Department of Chemistry, City University of Hong Kong, Hong Kong, China
| | - Hao Luo
- State Key Laboratory of Marine Environmental Science, Xiamen University, Xiamen, China
| | - Liying Yu
- State Key Laboratory of Marine Environmental Science, Xiamen University, Xiamen, China
| | - Wai Hin Lee
- State Key Laboratory of Marine Pollution, City University of Hong Kong, Hong Kong, China; Department of Biomedical Sciences, City University of Hong Kong, Hong Kong, China
| | - Ling Li
- State Key Laboratory of Marine Environmental Science, Xiamen University, Xiamen, China
| | - Yim Ling Mak
- State Key Laboratory of Marine Pollution, City University of Hong Kong, Hong Kong, China; Shenzhen Key Laboratory for the Sustainable Use of Marine Biodiversity, Research Centre for the Oceans and Human Health, City University of Hong Kong Shenzhen Research Institute, Shenzhen, China
| | - Senjie Lin
- State Key Laboratory of Marine Environmental Science, Xiamen University, Xiamen, China; Department of Marine Sciences, University of Connecticut, Groton, CT, USA.
| | - Paul K S Lam
- State Key Laboratory of Marine Pollution, City University of Hong Kong, Hong Kong, China; Department of Chemistry, City University of Hong Kong, Hong Kong, China; Shenzhen Key Laboratory for the Sustainable Use of Marine Biodiversity, Research Centre for the Oceans and Human Health, City University of Hong Kong Shenzhen Research Institute, Shenzhen, China
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21
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Akbar MA, Mohd Yusof NY, Tahir NI, Ahmad A, Usup G, Sahrani FK, Bunawan H. Biosynthesis of Saxitoxin in Marine Dinoflagellates: An Omics Perspective. Mar Drugs 2020; 18:md18020103. [PMID: 32033403 PMCID: PMC7073992 DOI: 10.3390/md18020103] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2019] [Revised: 01/09/2020] [Accepted: 01/09/2020] [Indexed: 02/07/2023] Open
Abstract
Saxitoxin is an alkaloid neurotoxin originally isolated from the clam Saxidomus giganteus in 1957. This group of neurotoxins is produced by several species of freshwater cyanobacteria and marine dinoflagellates. The saxitoxin biosynthesis pathway was described for the first time in the 1980s and, since then, it was studied in more than seven cyanobacterial genera, comprising 26 genes that form a cluster ranging from 25.7 kb to 35 kb in sequence length. Due to the complexity of the genomic landscape, saxitoxin biosynthesis in dinoflagellates remains unknown. In order to reveal and understand the dynamics of the activity in such impressive unicellular organisms with a complex genome, a strategy that can carefully engage them in a systems view is necessary. Advances in omics technology (the collective tools of biological sciences) facilitated high-throughput studies of the genome, transcriptome, proteome, and metabolome of dinoflagellates. The omics approach was utilized to address saxitoxin-producing dinoflagellates in response to environmental stresses to improve understanding of dinoflagellates gene–environment interactions. Therefore, in this review, the progress in understanding dinoflagellate saxitoxin biosynthesis using an omics approach is emphasized. Further potential applications of metabolomics and genomics to unravel novel insights into saxitoxin biosynthesis in dinoflagellates are also reviewed.
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Affiliation(s)
- Muhamad Afiq Akbar
- School of Bioscience and Biotechnology, Faculty of Science and Technology, Universiti Kebangsaan Malaysia, Bangi 43600, Malaysia;
| | - Nurul Yuziana Mohd Yusof
- Department of Earth Science and Environment, Faculty of Science and Technology, Universiti Kebangsaan Malaysia, Bangi 43600, Malaysia; (N.Y.M.Y.); (F.K.S.)
| | - Noor Idayu Tahir
- Malaysian Palm Oil Board, No 6, Persiaran Institusi, Bandar Baru Bangi, Kajang 43000, Selangor, Malaysia;
| | - Asmat Ahmad
- University College Sabah Foundation, Jalan Sanzac, Kota Kinabalu 88100, Sabah, Malaysia; (A.A.); (G.U.)
| | - Gires Usup
- University College Sabah Foundation, Jalan Sanzac, Kota Kinabalu 88100, Sabah, Malaysia; (A.A.); (G.U.)
| | - Fathul Karim Sahrani
- Department of Earth Science and Environment, Faculty of Science and Technology, Universiti Kebangsaan Malaysia, Bangi 43600, Malaysia; (N.Y.M.Y.); (F.K.S.)
| | - Hamidun Bunawan
- Institute of Systems Biology, Universiti Kebangsaan Malaysia, Bangi 43600, Malaysia
- Correspondence: ; Tel.: +60-389-214-546
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22
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Transcriptional and physiological responses to inorganic nutrition in a tropical Pacific strain of Alexandrium minutum: Implications for nutrient uptakes and assimilation. Gene 2019; 711:143950. [PMID: 31255736 DOI: 10.1016/j.gene.2019.143950] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2018] [Revised: 06/25/2019] [Accepted: 06/26/2019] [Indexed: 11/22/2022]
Abstract
The marine dinoflagellate Alexandrium minutum is known to produce saxitoxins that cause paralytic shellfish poisoning in human worldwide through consumption of the contaminated shellfish mollusks. Despite numerous studies on the growth physiology and saxitoxin production of this species, the knowledge on the molecular basis of nutrient uptakes in relation to toxin production in this species is limited. In this study, relative expressions of the high-affinity transporter genes of nitrate, ammonium, and phosphate (AmNrt2, AmAmt1 and AmPiPT1) and the assimilation genes, nitrate reductase (AmNas), glutamine synthase (AmGSIII) and carbamoyl phosphate synthase (AmCPSII) from A. minutum were studied in batch clonal culture condition with two nitrogen sources (nitrate: NO3- or ammonium: NH4+) under different N:P ratios (high-P: N:P of 14 and 16, and low-P: N:P of 155). The expression of AmAmt1 was suppressed in excess NH4+-grown condition but was not observed in AmNrt2 and AmNas. Expressions of AmAmt1, AmNrt2, AmNas, AmGSIII, AmCPSII, and AmPiPT1 were high in P-deficient condition, showing that A. minutum is likely to take up nutrients for growth under P-stress condition. Conversely, relative expression of AmCPSII was incongruent with cell growth, but was well correlated with toxin quota, suggesting that the gene might involve in arginine metabolism and related toxin production pathway. The expression of AmGSIII is found coincided with higher toxin production and is believed to involve in mechanism to detoxify the cells from excess ammonium stress. The gene regulation observed in this study has provided better insights into the ecophysiology of A. minutum in relation to its adaptive strategies in unfavorable environments.
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Verma A, Barua A, Ruvindy R, Savela H, Ajani PA, Murray SA. The Genetic Basis of Toxin Biosynthesis in Dinoflagellates. Microorganisms 2019; 7:E222. [PMID: 31362398 PMCID: PMC6722697 DOI: 10.3390/microorganisms7080222] [Citation(s) in RCA: 37] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2019] [Revised: 07/23/2019] [Accepted: 07/27/2019] [Indexed: 02/07/2023] Open
Abstract
In marine ecosystems, dinoflagellates can become highly abundant and even dominant at times, despite their comparatively slow growth rates. One factor that may play a role in their ecological success is the production of complex secondary metabolite compounds that can have anti-predator, allelopathic, or other toxic effects on marine organisms, and also cause seafood poisoning in humans. Our knowledge about the genes involved in toxin biosynthesis in dinoflagellates is currently limited due to the complex genomic features of these organisms. Most recently, the sequencing of dinoflagellate transcriptomes has provided us with valuable insights into the biosynthesis of polyketide and alkaloid-based toxin molecules in dinoflagellate species. This review synthesizes the recent progress that has been made in understanding the evolution, biosynthetic pathways, and gene regulation in dinoflagellates with the aid of transcriptomic and other molecular genetic tools, and provides a pathway for future studies of dinoflagellates in this exciting omics era.
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Affiliation(s)
- Arjun Verma
- Climate Change Cluster, University of Technology Sydney, Sydney 2007, Australia.
| | - Abanti Barua
- Climate Change Cluster, University of Technology Sydney, Sydney 2007, Australia
- Department of Microbiology, Noakhali Science and Technology University, Chittagong 3814, Bangladesh
| | - Rendy Ruvindy
- Climate Change Cluster, University of Technology Sydney, Sydney 2007, Australia
| | - Henna Savela
- Finnish Environment Institute, Marine Research Centre, 00790 Helsinki, Finland
| | - Penelope A Ajani
- Climate Change Cluster, University of Technology Sydney, Sydney 2007, Australia
| | - Shauna A Murray
- Climate Change Cluster, University of Technology Sydney, Sydney 2007, Australia
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15N Stable Isotope Labeling PSTs in Alexandrium minutum for Application of PSTs as Biomarker. Toxins (Basel) 2019; 11:toxins11040211. [PMID: 30965634 PMCID: PMC6521191 DOI: 10.3390/toxins11040211] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2019] [Revised: 04/04/2019] [Accepted: 04/04/2019] [Indexed: 12/17/2022] Open
Abstract
The dinoflagellate Alexandrium minutum (A. minutum) which can produce paralytic shellfish toxins (PSTs) is often used as a model to study the migration, biotransformation, accumulation, and removal of PSTs. However, the mechanism is still unclear. To provide a new tool for related studies, we tried to label PSTs metabolically with 15N stable isotope to obtain 15N-PSTs instead of original 14N, which could be treated as biomarker on PSTs metabolism. We then cultured the A. minutum AGY-H46 which produces toxins GTX1-4 in f/2 medium of different 15N/P concentrations. The 15N-PSTs’ toxicity and toxin profile were detected. Meanwhile, the 15N labeling abundance and 15N atom number of 15N-PSTs were identified. The 14N of PSTs produced by A. minutum can be successfully replaced by 15N, and the f/2 medium of standard 15N/P concentration was the best choice in terms of the species’ growth, PST profile, 15N labeling result and experiment cost. After many (>15) generations, the 15N abundance in PSTs extract reached 82.36%, and the 15N atom number introduced into GTX1-4 might be 4–6. This paper innovatively provided the initial evidence that 15N isotope application of labeling PSTs in A. minutum is feasible. The 15N-PSTs as biomarker can be applied and provide further information on PSTs metabolism.
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Lewis AM, Coates LN, Turner AD, Percy L, Lewis J. A review of the global distribution of Alexandrium minutum (Dinophyceae) and comments on ecology and associated paralytic shellfish toxin profiles, with a focus on Northern Europe. JOURNAL OF PHYCOLOGY 2018; 54:581-598. [PMID: 30047623 DOI: 10.1111/jpy.12768] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/08/2018] [Accepted: 06/21/2018] [Indexed: 06/08/2023]
Abstract
Alexandrium minutum is a globally distributed harmful algal bloom species with many strains that are known to produce paralytic shellfish toxins (PSTs) and consequently represent a concern to human and ecosystem health. This review highlights that A. minutum typically occurs in sheltered locations, with cell growth occurring during periods of stable water conditions. Sediment characteristics are important in the persistence of this species within a location, with fine sediments providing cyst deposits for ongoing inoculation to the water column. Toxic strains of A. minutum do not produce a consistent toxin profile, different populations produce a range of PSTs in differing quantities. Novel cluster analysis of published A. minutum toxin profiles indicates five PST profile clusters globally. Some clusters are grouped geographically (Northern Europe) while others are widely spread. Isolates from Taiwan have a range of toxin profile clusters and this area appears to have the most diverse set of PST producing A. minutum populations. These toxin profiles indicate that within the United Kingdom there are two populations of A. minutum grouping with strains from Northern France and Southern Ireland. There is a degree of interconnectivity in this region due to oceanic circulation and a high level of shipping and recreational boating. Further research into the interrelationships between the A. minutum populations in this global region would be of value.
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Affiliation(s)
- Adam Michael Lewis
- Cefas, The Nothe, Barrack Road, Weymouth, Dorset, DT48UB, UK
- Faculty of Science and Technology, The University of Westminster, 115 New Cavendish Street, London, W1W6UW, UK
| | | | - Andrew D Turner
- Cefas, The Nothe, Barrack Road, Weymouth, Dorset, DT48UB, UK
| | - Linda Percy
- Faculty of Science and Technology, The University of Westminster, 115 New Cavendish Street, London, W1W6UW, UK
| | - Jane Lewis
- Faculty of Science and Technology, The University of Westminster, 115 New Cavendish Street, London, W1W6UW, UK
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Er HH, Lee LK, Lim ZF, Teng ST, Leaw CP, Lim PT. Responses of phytoplankton community to eutrophication in Semerak Lagoon (Malaysia). ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2018; 25:22944-22962. [PMID: 29858995 DOI: 10.1007/s11356-018-2389-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/14/2017] [Accepted: 05/22/2018] [Indexed: 06/08/2023]
Abstract
Effects of aquaculture activities on the environmental parameters and phytoplankton community structure were investigated in a semi-enclosed lagoon located at Semerak River, Malaysia. Elevated concentrations of phosphate and ammonia were observed at the aquaculture area and the inner lagoon. Relatively low dissolved oxygen, high total chlorophyll a, and high phytoplankton abundances but low species richness were recorded. Chaetoceros, Pseudo-nitzschia brasiliana, Blixaea quinquecornis, and Skeletonema blooms were observed, and some were associated with anoxia condition. Eutrophication level assessed by UNTRIX suggests that the water quality in the lagoon is deteriorating. Dissolved inorganic phosphorus and nitrogen at the impacted area were 15 and 12 times higher than the reference sites, respectively. Such trophic status indices could provide a useful guideline for optimal aquaculture management plan to reduce the environmental impact caused by aquaculture.
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Affiliation(s)
- Huey Hui Er
- Bachok Marine Research Station, Institute of Ocean and Earth Sciences, University of Malaya, 16310, Bachok, Kelantan, Malaysia
| | - Li Keat Lee
- Bachok Marine Research Station, Institute of Ocean and Earth Sciences, University of Malaya, 16310, Bachok, Kelantan, Malaysia
| | - Zhen Fei Lim
- Bachok Marine Research Station, Institute of Ocean and Earth Sciences, University of Malaya, 16310, Bachok, Kelantan, Malaysia
| | - Sing Tung Teng
- Faculty of Resource Science and Technology, Universiti Malaysia Sarawak, 94300, Kota Samarahan, Sarawak, Malaysia
| | - Chui Pin Leaw
- Bachok Marine Research Station, Institute of Ocean and Earth Sciences, University of Malaya, 16310, Bachok, Kelantan, Malaysia.
| | - Po Teen Lim
- Bachok Marine Research Station, Institute of Ocean and Earth Sciences, University of Malaya, 16310, Bachok, Kelantan, Malaysia.
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Extending the "One Strain Many Compounds" (OSMAC) Principle to Marine Microorganisms. Mar Drugs 2018; 16:md16070244. [PMID: 30041461 PMCID: PMC6070831 DOI: 10.3390/md16070244] [Citation(s) in RCA: 156] [Impact Index Per Article: 26.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2018] [Revised: 07/17/2018] [Accepted: 07/19/2018] [Indexed: 02/07/2023] Open
Abstract
Genomic data often highlights an inconsistency between the number of gene clusters identified using bioinformatic approaches as potentially producing secondary metabolites and the actual number of chemically characterized secondary metabolites produced by any given microorganism. Such gene clusters are generally considered as “silent”, meaning that they are not expressed under laboratory conditions. Triggering expression of these “silent” clusters could result in unlocking the chemical diversity they control, allowing the discovery of novel molecules of both medical and biotechnological interest. Therefore, both genetic and cultivation-based techniques have been developed aimed at stimulating expression of these “silent” genes. The principles behind the cultivation based approaches have been conceptualized in the “one strain many compounds” (OSMAC) framework, which underlines how a single strain can produce different molecules when grown under different environmental conditions. Parameters such as, nutrient content, temperature, and rate of aeration can be easily changed, altering the global physiology of a microbial strain and in turn significantly affecting its secondary metabolism. As a direct extension of such approaches, co-cultivation strategies and the addition of chemical elicitors have also been used as cues to activate “silent” clusters. In this review, we aim to provide a focused and comprehensive overview of these strategies as they pertain to marine microbes. Moreover, we underline how changes in some parameters which have provided important results in terrestrial microbes, but which have rarely been considered in marine microorganisms, may represent additional strategies to awaken “silent” gene clusters in marine microbes. Unfortunately, the empirical nature of the OSMAC approach forces scientists to perform extensive laboratory experiments. Nevertheless, we believe that some computation and experimental based techniques which are used in other disciplines, and which we discuss; could be effectively employed to help streamline the OSMAC based approaches. We believe that natural products discovery in marine microorganisms would be greatly aided through the integration of basic microbiological approaches, computational methods, and technological innovations, thereby helping unearth much of the as yet untapped potential of these microorganisms.
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Lau WLS, Law IK, Liow GR, Hii KS, Usup G, Lim PT, Leaw CP. Life-history stages of natural bloom populations and the bloom dynamics of a tropical Asian ribotype of Alexandrium minutum. HARMFUL ALGAE 2017; 70:52-63. [PMID: 29169568 DOI: 10.1016/j.hal.2017.10.006] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/15/2017] [Revised: 10/30/2017] [Accepted: 10/30/2017] [Indexed: 06/07/2023]
Abstract
In 2015, a remarkably high density bloom of Alexandrium minutum occurred in Sungai Geting, a semi-enclosed lagoon situated in the northeast of Peninsular Malaysia, causing severe discoloration and contaminated the benthic clams (Polymesoda). Plankton and water samples were collected to investigate the mechanisms of bloom development of this toxic species. Analysis of bloom samples using flow cytometry indicated that the bloom was initiated by the process of active excystment, as planomycetes (>4C cells) were observed in the early stage of the bloom. Increase in planozygotes (2C cells) was evident during the middle stage of the bloom, coinciding with an abrupt decrease in salinity and increase of temperature. The bloom was sustained through the combination of binary division of vegetative cells, division of planozygotes, and cyst germination through continuous excystment. Nutrient depletion followed by precipitation subsequently caused the bloom to terminate. This study provides the first continuous record of in situ life-cycle stages of a natural bloom population of A. minutum through a complete bloom cycle. The event has provided a fundamental understanding of the pelagic life-cycle stages of this tropical dinoflagellate, and demonstrated a unique bloom development characteristic shared among toxic Alexandrium species in coastal embayments.
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Affiliation(s)
- Winnie Lik Sing Lau
- Institute of Ocean and Earth Sciences, University of Malaya, 16310 Bachok, Kelantan, Malaysia
| | - Ing Kuo Law
- Institute of Ocean and Earth Sciences, University of Malaya, 16310 Bachok, Kelantan, Malaysia
| | - Guat Ru Liow
- Institute of Ocean and Earth Sciences, University of Malaya, 16310 Bachok, Kelantan, Malaysia
| | - Kieng Soon Hii
- Institute of Ocean and Earth Sciences, University of Malaya, 16310 Bachok, Kelantan, Malaysia
| | - Gires Usup
- Faculty of Science and Technology, Universiti Kebangsaan Malaysia, 43600 Bangi, Malaysia
| | - Po Teen Lim
- Institute of Ocean and Earth Sciences, University of Malaya, 16310 Bachok, Kelantan, Malaysia.
| | - Chui Pin Leaw
- Institute of Ocean and Earth Sciences, University of Malaya, 16310 Bachok, Kelantan, Malaysia.
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Lugliè A, Giacobbe MG, Riccardi E, Bruno M, Pigozzi S, Mariani MA, Satta CT, Stacca D, Bazzoni AM, Caddeo T, Farina P, Padedda BM, Pulina S, Sechi N, Milandri A. Paralytic Shellfish Toxins and Cyanotoxins in the Mediterranean: New Data from Sardinia and Sicily (Italy). Microorganisms 2017; 5:microorganisms5040072. [PMID: 29144421 PMCID: PMC5748581 DOI: 10.3390/microorganisms5040072] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2017] [Revised: 11/12/2017] [Accepted: 11/13/2017] [Indexed: 12/14/2022] Open
Abstract
Harmful algal blooms represent a severe issue worldwide. They affect ecosystem functions and related services and goods, with consequences on human health and socio-economic activities. This study reports new data on paralytic shellfish toxins (PSTs) from Sardinia and Sicily (Italy), the largest Mediterranean islands where toxic events, mainly caused by Alexandrium species (Dinophyceae), have been ascertained in mussel farms since the 2000s. The toxicity of the A. minutum, A. tamarense and A. pacificum strains, established from the isolation of vegetative cells and resting cysts, was determined by high performance liquid chromatography (HPLC). The analyses indicated the highest toxicity for A. pacificum strains (total PSTs up to 17.811 fmol cell-1). The PSTs were also assessed in a strain of A. tamarense. The results encourage further investigation to increase the knowledge of toxic species still debated in the Mediterranean. This study also reports new data on microcystins (MCs) and β-N-methylamino-L-alanine (BMAA) from a Sardinian artificial lake (Lake Bidighinzu). The presence of MCs and BMAA was assessed in natural samples and in cell cultures by enzyme-linked immunosorbent assay (ELISA). BMAA positives were found in all the analysed samples with a maximum of 17.84 µg L-1. The obtained results added further information on cyanotoxins in Mediterranean reservoirs, particularly BMAA, which have not yet been thoroughly investigated.
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Affiliation(s)
- Antonella Lugliè
- Dipartimento di Architettura, Design e Urbanistica, University of Sassari, Via Piandanna 4, 07100 Sassari, Italy.
| | - Maria Grazia Giacobbe
- Istituto per l'Ambiente Marino Costiero, CNR, Spianata S. Raineri 86, 98122 Messina, Italy.
| | - Elena Riccardi
- Fondazione Centro Ricerche Marine, National Reference Laboratory for Marine Biotoxins, Viale A. Vespucci 2, 47042 Cesenatico (FC), Italy.
| | - Milena Bruno
- Environmental Quality and Fish Farming, Environment and Primary Prevention, Istituto Superiore di Sanità, V.le Regina Elena 299, 00161 Rome, Italy.
| | - Silvia Pigozzi
- Fondazione Centro Ricerche Marine, National Reference Laboratory for Marine Biotoxins, Viale A. Vespucci 2, 47042 Cesenatico (FC), Italy.
| | - Maria Antonietta Mariani
- Dipartimento di Architettura, Design e Urbanistica, University of Sassari, Via Piandanna 4, 07100 Sassari, Italy.
| | - Cecilia Teodora Satta
- Dipartimento di Architettura, Design e Urbanistica, University of Sassari, Via Piandanna 4, 07100 Sassari, Italy.
- Agenzia Regionale per la Ricerca in Agricoltura (AGRIS), Servizio Ittico, S.S. Sassari-Fertilia Km 18,600, Bonassai, 07040 Olmedo, Italy.
| | - Daniela Stacca
- Dipartimento di Architettura, Design e Urbanistica, University of Sassari, Via Piandanna 4, 07100 Sassari, Italy.
| | - Anna Maria Bazzoni
- Dipartimento di Ispezione degli Alimenti, Istituto Zooprofilattico Sperimentale della Sardegna G. Pegreffi, Via Duca degli Abruzzi 8, 07100 Sassari, Italy.
| | - Tiziana Caddeo
- Dipartimento di Architettura, Design e Urbanistica, University of Sassari, Via Piandanna 4, 07100 Sassari, Italy.
| | - Pasqualina Farina
- Dipartimento di Architettura, Design e Urbanistica, University of Sassari, Via Piandanna 4, 07100 Sassari, Italy.
| | - Bachisio Mario Padedda
- Dipartimento di Architettura, Design e Urbanistica, University of Sassari, Via Piandanna 4, 07100 Sassari, Italy.
| | - Silvia Pulina
- Dipartimento di Architettura, Design e Urbanistica, University of Sassari, Via Piandanna 4, 07100 Sassari, Italy.
- Department of Life and Environmental Sciences, University of Cagliari, Via Fiorelli 1, 09126 Cagliari, Italy.
| | - Nicola Sechi
- Dipartimento di Architettura, Design e Urbanistica, University of Sassari, Via Piandanna 4, 07100 Sassari, Italy.
| | - Anna Milandri
- Fondazione Centro Ricerche Marine, National Reference Laboratory for Marine Biotoxins, Viale A. Vespucci 2, 47042 Cesenatico (FC), Italy.
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