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Hano T, Tomaru Y. Chronological age-related metabolome responses in the dinoflagellate Karenia mikimotoi, can predict future bloom demise. Commun Biol 2023; 6:273. [PMID: 36922623 PMCID: PMC10017670 DOI: 10.1038/s42003-023-04646-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2022] [Accepted: 03/01/2023] [Indexed: 03/18/2023] Open
Abstract
Karenia mikimotoi is a common harmful algal bloom (HAB)-forming dinoflagellate and has caused severe financial loss in aquaculture. There are limited metabolomic studies on dinoflagellate biology. Here, we examined alterations in metabolic profiles over the growth curve of K. mikimotoi under nitrogen or phosphorus deficiency and further explored a key criterion for the diagnosis of late stationary phase to identify when the dinoflagellate cells will enter bloom demise. The results demonstrate the differential expression of metabolites for coping with chronological aging or nutrient deprivation. Furthermore, an increase in the glucose to glycine ratio in the late stationary phase was indicative of dinoflagellate cells entering bloom demise; this was also detected in the cultured diatom, Chaetoceros tenuissimus, indicating that this may be the general criterion for phytoplankton species. Our findings provide insights regarding chronological aging and the criterion for the prediction of phytoplankton bloom demise.
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Affiliation(s)
- Takeshi Hano
- Environment Conservation Division, Fisheries Technology Institute, National Research and Development Agency, Japan Fisheries Research and Education Agency, 2-17-5 Maruishi, Hatsukaichi, Hiroshima, 739-0452, Japan.
| | - Yuji Tomaru
- Environment Conservation Division, Fisheries Technology Institute, National Research and Development Agency, Japan Fisheries Research and Education Agency, 2-17-5 Maruishi, Hatsukaichi, Hiroshima, 739-0452, Japan
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Yue C, Chai Z, Hu Z, Shang L, Deng Y, Tang YZ. Deficiency of nitrogen but not phosphorus triggers the life cycle transition of the dinoflagellate Scrippsiella acuminata from vegetative growth to resting cyst formation. HARMFUL ALGAE 2022; 118:102312. [PMID: 36195426 DOI: 10.1016/j.hal.2022.102312] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/06/2022] [Revised: 08/17/2022] [Accepted: 08/18/2022] [Indexed: 06/16/2023]
Abstract
Nitrogen (N) and phosphorus (P) are essential elements for algal growth. When N and P are deficient, dinoflagellates will take a series of measures to achieve population continuation including formation of resting cysts, an important ecological strategy of dinoflagellates that plays a key role in the initiation and termination of harmful algal blooms (HABs). How the deficiency of N and P affects algal growth and cyst formation has been investigated in some dinoflagellate species, but how it affects the life cycle transition in dinoflagellates has been poorly understood. In this study, we further explored the effect of N and P deficiency on the algal growth and resting cyst production in the cosmopolitan HABs-causing species Scrippsiella acuminata via refining the N and P concentration gradients. Further, we tracked the expression patterns of one CyclinB and one CDK1 genes of S. acuminata at different growth stages under three deficiency concentrations (1/1000 dilutions of N, P, and both N and P). The results suggest that N deficiency always triggered the cyst formation but P deficiency mainly inhibited the vegetative growth instead of inducing cyst formation. We also observed the highest cyst production when S. acuminata was cultured in the f/2-Si medium that was a one-thousandth dilution of N and P (N∼ 0.882 μM; P∼ 0.0362 μM). Our results for the expressions of CyclinB and CDK1 were well consistent with the results of algal growth and cyst formation at different deficiencies of N and P in terms of that higher expressions of these two genes were corresponding to higher rates of vegetative cell growth, while their expressions in resting cysts maintained to be moderate but significantly lower than that in fast-growing vegetative cells. Although we are still not sure whether the changing expressions of the two genes did regulate the transition of life cycle (i.e. cyst formation), or happened as parallels to the expressions of other truly regulating genes, our observations are surely inspirational for further investigations on the genetic regulation of life cycle transition in dinoflagellates. Our work will provide clues to probe the physiological and molecular mechanisms underlying the nutrient deficiency-induced alternation between life cycle stages in dinoflagellates.
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Affiliation(s)
- Caixia Yue
- CAS Key Laboratory of Marine Ecology and Environmental Sciences, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, 266071, China; University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Zhaoyang Chai
- CAS Key Laboratory of Marine Ecology and Environmental Sciences, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, 266071, China; Laboratory of Marine Ecology and Environmental Science, Qingdao National Laboratory for Marine Science and Technology, Qingdao, 266237, China; Center for Ocean Mega-Science, Chinese Academy of Sciences, Qingdao, 266071, China
| | - Zhangxi Hu
- CAS Key Laboratory of Marine Ecology and Environmental Sciences, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, 266071, China; Laboratory of Marine Ecology and Environmental Science, Qingdao National Laboratory for Marine Science and Technology, Qingdao, 266237, China; Center for Ocean Mega-Science, Chinese Academy of Sciences, Qingdao, 266071, China
| | - Lixia Shang
- CAS Key Laboratory of Marine Ecology and Environmental Sciences, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, 266071, China; Laboratory of Marine Ecology and Environmental Science, Qingdao National Laboratory for Marine Science and Technology, Qingdao, 266237, China; Center for Ocean Mega-Science, Chinese Academy of Sciences, Qingdao, 266071, China
| | - Yunyan Deng
- CAS Key Laboratory of Marine Ecology and Environmental Sciences, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, 266071, China; Laboratory of Marine Ecology and Environmental Science, Qingdao National Laboratory for Marine Science and Technology, Qingdao, 266237, China; Center for Ocean Mega-Science, Chinese Academy of Sciences, Qingdao, 266071, China.
| | - Ying Zhong Tang
- CAS Key Laboratory of Marine Ecology and Environmental Sciences, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, 266071, China; Laboratory of Marine Ecology and Environmental Science, Qingdao National Laboratory for Marine Science and Technology, Qingdao, 266237, China; Center for Ocean Mega-Science, Chinese Academy of Sciences, Qingdao, 266071, China.
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Wang Z, Xie C, Zhang J, Ji S, Zhao J, Nie X. The responses of Scrippsiella acuminata to the stresses of darkness: antioxidant activities and formation of pellicle cysts. HARMFUL ALGAE 2022; 115:102239. [PMID: 35623691 DOI: 10.1016/j.hal.2022.102239] [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: 11/18/2021] [Revised: 03/03/2022] [Accepted: 04/20/2022] [Indexed: 06/15/2023]
Abstract
In order to understand the strategy of Scrippsiella acuminata to cold dark environment, the antioxidant responses and the formation of pellicle cysts of S. acuminata to darkness at 8°C and 20°C were investigated. Cell densities decreased significantly after 96 h dark treatment, and no live cells were observed after 9-days dark treatments. The darkness stress generally resulted in an increase of antioxidant defenses, including soluble protein, superoxide dismutase (SOD), glutathione (GSH), and malondialdehyde (MDA). Cellular soluble protein and SOD activity increased sharply under 20°C darkness, which protected algal cells against the oxidative stress from darkness, and resulted in relatively lower MDA levels. Soluble protein and SOD activity were enhanced under 8°C darkness as well however not in a sharp rise, and higher levels of MDA and GSH were recorded. The results suggested high SOD and protein levels protected cells against harsh darkness stress, while high GSH not only helped algae cells resist dark stress, but also played an important role in low temperature stress. Darkness promoted the formation of pellicle cysts of S. acuminata, and the maximum formation rates were 16.06% to 21.74% at 8°C and 20°C, respectively. Germination of pellicle cysts occurred within 24 h after light exposure, however pellicle cysts could not withstand long-time darkness stress, and all pellicle cysts died after 9-days darkness exposure. The results of this study suggest that S. acuminata is able to overcome temporary cold darkness through forming pellicle cysts.
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Affiliation(s)
- Zhaohui Wang
- College of Life Science and Technology, Jinan University, Guangzhou, 510632, China.
| | - Changliang Xie
- College of Life Science and Technology, Jinan University, Guangzhou, 510632, China
| | - Jianneng Zhang
- College of Life Science and Technology, Jinan University, Guangzhou, 510632, China
| | - Shuanghui Ji
- College of Life Science and Technology, Jinan University, Guangzhou, 510632, China
| | - Jiangang Zhao
- College of Life Science and Technology, Jinan University, Guangzhou, 510632, China.
| | - Xiangping Nie
- College of Life Science and Technology, Jinan University, Guangzhou, 510632, China.
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A Novel Algicidal Bacterium and Its Effects against the Toxic Dinoflagellate Karenia mikimotoi (Dinophyceae). Microbiol Spectr 2022; 10:e0042922. [PMID: 35616372 PMCID: PMC9241683 DOI: 10.1128/spectrum.00429-22] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The toxic dinoflagellate Karenia mikimotoi is a harmful algal bloom-forming species in coastal areas around the world. It produces ichthyotoxins and hemolytic toxins, with deleterious effects on marine ecosystems. In this study, the bacterium Pseudoalteromonas sp. FDHY-MZ2, with high algicidal efficiency against K. mikimotoi, was isolated from a bloom event. Based on the results, it completely lysed K. mikimotoi cells within 24 h 0.5% (vol/vol), with the algicidal activity of the supernatant of the bacterium culture. Algal cell wall fragmentation occurred, leading to cell death. There was a marked decline in various photochemical traits. When treated with the supernatant, cellulase, pheophorbide a oxygenase (PAO) and cyclin B genes were significantly increased, suggesting induced cell wall deterioration, chloroplast degradation and cell cycle regulation of K. mikimotoi cells. In addition, the expression levels of reactive oxygen species (ROS) scavenging gene was significantly inhibited, indicating that the ROS removal system was damaged. The bacterial culture was dried to obtain the spray-dried powder, which showed algicidal activity rates of 92.2 and 100% against a laboratory K. mikimotoi culture and a field microcosm of Karlodinium sp. bloom within 24 h with the addition of 0.04% mass fraction powder. Our results demonstrate that FDHY-MZ2 is a suitable strain for K. mikimotoi and Karlodinium sp. blooms management. In addition, this study provides a new strategy for the anthropogenic control of harmful algal bloom-forming species in situ. IMPORTANCE K. mikimotoi is a noxious algal bloom-forming species that cause damaging of the aquaculture industry and great financial losses. Bacterium with algicidal activity is an ideal agency to inhibit the growth of harmful algae. In this approach application, the bacterium with high algicidal activity is required and the final management material is ideal for easy-to-use. The algicidal characteristics are also needed to understand the effects of the bacterium for managing strategy exploration. In this study, we isolated a novel algicidal bacterium with extremely high lysis efficiency for K. mikimotoi. The algicidal characteristics of the bacterium as well as the chemical and molecular response of K. mikimotoi with the strain challenge were examined. Finally, the algicidal powder was explored for application. The results demonstrate that FDHY-MZ2 is suitable for K. mikimotoi and Karlodinium sp. blooms controlling, and this study provides a new strategy for algicidal bacterium application.
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Liu Q, Wang Y, Li Y, Li Y, Wang Y, Zhou B, Zhou Z. Nutrient Alteration Drives the Impacts of Seawater Acidification on the Bloom-Forming Dinoflagellate Karenia mikimotoi. FRONTIERS IN PLANT SCIENCE 2021; 12:739159. [PMID: 34751224 PMCID: PMC8572056 DOI: 10.3389/fpls.2021.739159] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/10/2021] [Accepted: 09/30/2021] [Indexed: 06/13/2023]
Abstract
Seawater acidification and nutrient alteration are two dominant environmental factors in coastal environments that influence the dynamics and succession of marine microalgae. However, the impacts of their combination have seldom been recorded. A simulated experimental system was set up to mimic the effects of elevated acidification on a bloom-forming dinoflagellate, Karenia mikimotoi, exposed to different nutrient conditions, and the possible mechanism was discussed. The results showed that acidification at different pH levels of 7.6 or 7.4 significantly influenced microalgal growth (p<0.05) compared with the control at pH 8.0. Mitochondria, the key sites of aerobic respiration and energy production, were impaired in a pH-dependent manner, and a simultaneous alteration of reactive oxygen species (ROS) production occurred. Cytochrome c oxidase (COX) and citrate synthase (CS), two mitochondrial metabolism-related enzymes, were actively induced with acidification exposure, suggesting the involvement of the mitochondrial pathway in coping with acidification. Moreover, different nutrient statuses indicated by various N:P ratios of 7:1 (N limitation) and 52:1 (P limitation) dramatically altered the impacts of acidification compared with those exposed to an N:P ratio of 17:1 (control), microalgal growth at pH 7.4 was obviously accelerated with the elevation of the nutrient ratio compared to that at pH 8.1 (p<0.05), and nutrient limitations seemed beneficial for growth in acidifying conditions. The production of alkaline phosphatase (AP) and acid phosphatase (AcP), an effective index indicating the microalgal growth status, significantly increased at the same time (p<0.05), which further supported this speculation. However, nitrate reductase (NR) was slightly inhibited. Hemolytic toxin production showed an obvious increase as the N:P ratio increased when exposed to acidification. Taken together, mitochondrial metabolism was suspected to be involved in the process of coping with acidification, and nutrient alterations, especially P limitation, could effectively alleviate the negative impacts induced by acidification. The obtained results might be a possible explanation for the competitive fitness of K. mikimotoi during bloom development.
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Affiliation(s)
- Qian Liu
- College of Marine Life Science, Ocean University of China, Qingdao, China
- Laboratory for Marine Ecology and Environmental Science, Pilot National Laboratory for Marine Science and Technology, Qingdao, China
| | - Yanqun Wang
- College of Environmental Science and Engineering, Ocean University of China, Qingdao, China
| | - Yuanyuan Li
- College of Marine Life Science, Ocean University of China, Qingdao, China
| | - Yijun Li
- College of Life Sciences, Qingdao University, Qingdao, China
| | - You Wang
- College of Marine Life Science, Ocean University of China, Qingdao, China
- Laboratory for Marine Ecology and Environmental Science, Pilot National Laboratory for Marine Science and Technology, Qingdao, China
| | - Bin Zhou
- College of Marine Life Science, Ocean University of China, Qingdao, China
- Laboratory for Marine Ecology and Environmental Science, Pilot National Laboratory for Marine Science and Technology, Qingdao, China
| | - Zhongyuan Zhou
- College of Marine Life Science, Ocean University of China, Qingdao, China
- Laboratory for Marine Ecology and Environmental Science, Pilot National Laboratory for Marine Science and Technology, Qingdao, China
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Shi X, Xiao Y, Liu L, Xie Y, Ma R, Chen J. Transcriptome responses of the dinoflagellate Karenia mikimotoi driven by nitrogen deficiency. HARMFUL ALGAE 2021; 103:101977. [PMID: 33980427 DOI: 10.1016/j.hal.2021.101977] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/19/2020] [Revised: 01/13/2021] [Accepted: 01/14/2021] [Indexed: 06/12/2023]
Abstract
The availability of ambient N nutrient is often correlated with the occurrences of harmful algal bloom formed by certain dinoflagellates, making it important to understand how these species might be responding to such conditions. Here, transcriptome sequencing of Karenia mikimotoi was conducted to understand the underlying molecular mechanisms by which this dinoflagellate copes with nitrogen (N) deficiency. Transcriptomic analysis revealed 8802 unigenes (3.56%) that were differentially expressed with ≥ 2-fold change. Under N-depleted conditions, genes involved in glycolysis, fatty acid metabolism, and the tricarboxylic acid (TCA) cycle as well as lipid accumulation were significantly upregulated. The elevated expression of enzymes used in protein degradation and turnover suggests possible metabolic reconfiguration towards accelerated N recycling. Moreover, a significant increase in urea transporter was observed, indicating increased assimilation of organic nitrogen resources as an alternative in N-depleted cultures of K. mikimotoi. The down-regulated glutamate synthase genes were also identified under N deficiency, suggesting suppression of primary amino acid synthesis to save N resource. Taken together, results of this study show enhanced multiple N resource acquisition and reuse of multiple N resources constitute a comprehensive strategy to cope with N deficiency in a dinoflagellate.
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Affiliation(s)
- Xinguo Shi
- Fujian Engineering Research Center for Comprehensive Utilization of Marine Products Waste, Fuzhou University, Fujian 350116, China; Fujian Key Laboratory of Marine Enzyme Engineering, Fuzhou University, Fujian 350116, China.
| | - Yuchun Xiao
- Fujian Key Laboratory of Marine Enzyme Engineering, Fuzhou University, Fujian 350116, China
| | - Lemian Liu
- Fujian Engineering Research Center for Comprehensive Utilization of Marine Products Waste, Fuzhou University, Fujian 350116, China; Fujian Key Laboratory of Marine Enzyme Engineering, Fuzhou University, Fujian 350116, China
| | - Youping Xie
- Fujian Engineering Research Center for Comprehensive Utilization of Marine Products Waste, Fuzhou University, Fujian 350116, China; Fujian Key Laboratory of Marine Enzyme Engineering, Fuzhou University, Fujian 350116, China
| | - Ruijuan Ma
- Fujian Engineering Research Center for Comprehensive Utilization of Marine Products Waste, Fuzhou University, Fujian 350116, China; Fujian Key Laboratory of Marine Enzyme Engineering, Fuzhou University, Fujian 350116, China
| | - Jianfeng Chen
- Fujian Engineering Research Center for Comprehensive Utilization of Marine Products Waste, Fuzhou University, Fujian 350116, China; Fujian Key Laboratory of Marine Enzyme Engineering, Fuzhou University, Fujian 350116, China.
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Identification of Polyunsaturated Fatty Acids Synthesis Pathways in the Toxic Dinophyte Alexandrium minutum Using 13C-Labelling. Biomolecules 2020; 10:biom10101428. [PMID: 33050104 PMCID: PMC7600785 DOI: 10.3390/biom10101428] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2020] [Revised: 09/26/2020] [Accepted: 10/07/2020] [Indexed: 11/16/2022] Open
Abstract
The synthetic pathways responsible for the production of the polyunsaturated fatty acids 22:6n-3 and 20:5n-3 were studied in the Dinophyte Alexandrium minutum. The purpose of this work was to follow the progressive incorporation of an isotopic label (13CO2) into 11 fatty acids to better understand the fatty acid synthesis pathways in A. minutum. The Dinophyte growth was monitored for 54 h using high-frequency sampling. A. minutum presented a growth in two phases. A lag phase was observed during the first 30 h of development and had been associated with the probable temporary encystment of Dinophyte cells. An exponential growth phase was then observed after t30. A. minutum rapidly incorporated 13C into 22:6n-3, which ended up being the most 13C-enriched polyunsaturated fatty acid (PUFA) in this experiment, with a higher 13C atomic enrichment than 18:4n-3, 18:5n-3, 20:5n-3, and 22:5n-3. Overall, the 13C atomic enrichment (AE) was inversely proportional to number of carbons in n-3 PUFA. C18 PUFAs, 18:4n-3, and 18:5n-3, were indeed among the least 13C-enriched FAs during this experiment. They were assumed to be produced by the n-3 PUFA pathway. However, they could not be further elongated or desaturated to produce n-3 C20-C22 PUFA, because the AEs of the n-3 C18 PUFAs were lower than those of the n-3 C20-C22 PUFAs. Thus, the especially high atomic enrichment of 22:6n-3 (55.8% and 54.9% in neutral lipids (NLs) and polar lipids (PLs), respectively) led us to hypothesize that this major PUFA was synthesized by an O2-independent Polyketide Synthase (PKS) pathway. Another parallel PKS, independent of the one leading to 22:6n-3, was also supposed to produce 20:5n-3. The inverse order of the 13C atomic enrichment for n-3 PUFAs was also suspected to be related to the possible β-oxidation of long-chain n-3 PUFAs occurring during A. minutum encystment.
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Liu Y, Hu Z, Deng Y, Tang YZ. Evidence for Production of Sexual Resting Cysts by the Toxic Dinoflagellate Karenia mikimotoi in Clonal Cultures and Marine Sediments. JOURNAL OF PHYCOLOGY 2020; 56:121-134. [PMID: 31560797 DOI: 10.1111/jpy.12925] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/09/2018] [Accepted: 09/09/2019] [Indexed: 06/10/2023]
Abstract
The toxic dinoflagellate Karenia mikimotoi has been well-known for causing large-scale and dense harmful algal blooms (HABs) in coastal waters worldwide and serious economic loss in aquaculture and fisheries and other adverse effects on marine ecosystems. Whether K. mikimotoi forms resting cysts has been a puzzling issue regarding to the mechanisms of bloom initiation and geographic expansion of this species. We provide morphological and molecular confirmation of sexually produced thin-walled resting cysts by K. mikimotoi based on observations of laboratory cultures and their direct detection in marine sediments. Light and scanning electron microscopy evidences for sexual reproduction include attraction and pairing of gametes, gamete fusion, formation of planozygote and thin-walled cyst, and the documentation of the thin-walled cyst germination processes. Evidence for cysts in marine sediments was in three aspects: positive PCR detection of cysts using species-specific primers in the DNA extracted from whole sediments; fluorescence in situ hybridization detection of cysts using FISH probes; and single-cell PCR sequencing for cysts positively labeled with FISH probes. The existence of sexually produced, thin-walled resting cysts by K. mikimotoi provides a possible mechanism accounting for the initiation of annually recurring blooms at certain regions and global expansion of the species during the past decades.
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Affiliation(s)
- Yuyang Liu
- CAS Key Laboratory of Marine Ecology and Environmental Sciences, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, 266071, China
- Laboratory for Marine Ecology and Environmental Science, Qingdao National Laboratory for Marine Science and Technology, Qingdao, 266237, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Zhangxi Hu
- CAS Key Laboratory of Marine Ecology and Environmental Sciences, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, 266071, China
- Laboratory for Marine Ecology and Environmental Science, Qingdao National Laboratory for Marine Science and Technology, Qingdao, 266237, China
- Center for Ocean Mega-Science, Chinese Academy of Sciences, Qingdao, 266071, China
| | - Yunyan Deng
- CAS Key Laboratory of Marine Ecology and Environmental Sciences, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, 266071, China
- Laboratory for Marine Ecology and Environmental Science, Qingdao National Laboratory for Marine Science and Technology, Qingdao, 266237, China
- Center for Ocean Mega-Science, Chinese Academy of Sciences, Qingdao, 266071, China
| | - Ying Zhong Tang
- CAS Key Laboratory of Marine Ecology and Environmental Sciences, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, 266071, China
- Laboratory for Marine Ecology and Environmental Science, Qingdao National Laboratory for Marine Science and Technology, Qingdao, 266237, China
- Center for Ocean Mega-Science, Chinese Academy of Sciences, Qingdao, 266071, China
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Li X, Yan T, Yu R, Zhou M. A review of karenia mikimotoi: Bloom events, physiology, toxicity and toxic mechanism. HARMFUL ALGAE 2019; 90:101702. [PMID: 31806160 DOI: 10.1016/j.hal.2019.101702] [Citation(s) in RCA: 54] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/21/2019] [Revised: 09/10/2019] [Accepted: 10/28/2019] [Indexed: 06/10/2023]
Abstract
Karenia mikimotoi is a worldwide bloom-forming dinoflagellate in the genus Karenia. Blooms of this alga have been observed since the 1930s and have caused mass mortalities of fish, shellfish, and other invertebrates in the coastal waters of many countries, including Japan, Norway, Ireland, and New Zealand. This species has frequently bloomed in China, causing great financial losses (more than 2 billion yuan, Fujian Province, 2012). K. mikimotoi can adapt to various light, temperature, salinity, and nutrient conditions, which together with its complex life history, strong motility, and density-dependent allelopathy, allows it to form blooms that are lethal to almost all marine organisms. However, its toxicity differs between subspecies and some target-species-specific toxicity has also been recorded. Significant gill disorder is observed in affected fish, to which the massive fish kills are attributed, rather than to the hypoxia that occurs in the fading stage of a bloom. However, although this species is haemolytic and cytotoxic, and generates reactive oxygen species, none of the isolated toxins or lipophilic extracts have toxic effects as extreme as those of the intact algal cells. The toxic effects of K. mikimotoi are strongly related to contact with intact cells. Several reasonable hypotheses of how and why this species blooms and causes mass mortalities have been proposed, but further research is required.
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Affiliation(s)
- Xiaodong Li
- Key Laboratory of Marine Biotechnology of Fujian Province, Institute of Oceanology, College of Animal Sciences, Fujian Agriculture and Forestry University, Fuzhou, Fujian Province, 350002, China; Key Laboratory of Marine Ecology and Environmental Sciences, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, Shandong Province, 266071, China.
| | - Tian Yan
- Key Laboratory of Marine Ecology and Environmental Sciences, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, Shandong Province, 266071, China; Laboratory of Marine Ecology and Environmental Science, Qingdao National Laboratory for Marine Science and Technology, Qingdao, Shandong Province, 266071, China; Centre for Ocean Mega-Science, Chinese Academy of Sciences, Qingdao, China.
| | - Rencheng Yu
- Key Laboratory of Marine Ecology and Environmental Sciences, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, Shandong Province, 266071, China; Laboratory of Marine Ecology and Environmental Science, Qingdao National Laboratory for Marine Science and Technology, Qingdao, Shandong Province, 266071, China; Centre for Ocean Mega-Science, Chinese Academy of Sciences, Qingdao, China
| | - Mingjiang Zhou
- Key Laboratory of Marine Ecology and Environmental Sciences, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, Shandong Province, 266071, China
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Brevetoxin-Producing Spherical Cells Present in Karenia brevis Bloom: Evidence of Morphological Plasticity? JOURNAL OF MARINE SCIENCE AND ENGINEERING 2019. [DOI: 10.3390/jmse7020024] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Spherical cells were detected in low salinity waters during a bloom of Karenia brevis in Alabama coastal waters. These balls resembled K. brevis in size and organelle appearance, contained similar concentration of brevetoxin, and occurred during ongoing K. brevis bloom. Based on the environmental conditions in which these cells were observed, we speculate that a rapid drop in salinity triggered the sphere formation in K. brevis. Brevetoxin concentrations were comparable between surface water samples containing typical and atypical cells ranging from 1 to 10 ng/mL brevetoxin-3 equivalents. Accurate identification and quantification of cell abundance in the water column is essential for routine monitoring of coastal waters, so misidentification of these spherical cells may result in significant underestimation of cell densities, and consequently, brevetoxin level. These potential discrepancies may negatively impact the quality of regulatory decisions and their impact on shellfish harvest area closures. We demonstrate that traditional monitoring based on microscopy alone is not sufficient for brevetoxin detection, and supporting toxin data is necessary to evaluate potential risk.
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