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Lu J, Niu X, Wang H, Zhang H, Guan W. Toxic dinoflagellate Karenia mikimotoi induces apoptosis in Neuro-2a cells through an oxidative stress-mediated mitochondrial pathway. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2023; 267:115667. [PMID: 37944466 DOI: 10.1016/j.ecoenv.2023.115667] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/15/2023] [Revised: 11/01/2023] [Accepted: 11/04/2023] [Indexed: 11/12/2023]
Abstract
The dinoflagellate Karenia mikimotoi is a toxic bloom-forming species that threatens aquaculture and public health worldwide. Previous studies showed that K. mikimotoi induces neurotoxicity; however, the underlying mechanism is poorly understood. In this study, three neural cell lines were used to investigate the potential neurotoxicity of K. mikimotoi. The tested cells were exposed to a ruptured cell solution (RCS) of K. mikimotoi at different concentrations (0.5 × 105, 1.0 × 105, 2.0 × 105, 4.0 × 105, and 6 × 105 cells mL-1) for 24 h, and the RCS decreased cell viabilities and promoted Neuro-2a (N2A) cell apoptosis in a dose-dependent manner. The underlying mechanism was further investigated in N2A cells. At the biochemical level, the RCS stimulated reactive oxygen species (ROS) and malondialdehyde (MDA) formation, decreased SOD activity, and reduced mitochondrial membrane potential (MMP). At the gene level, the moderate RCS treatment (2.0 × 105 cells mL-1) upregulated antioxidant response genes (e.g., nrf-2, HO-1, NQO-1, and cat) to alleviate RCS-induced oxidative stress, while the high RCS treatment (4.0 × 105 cells mL-1) downregulated these genes, thereby aggravating oxidative stress. Meanwhile, apoptosis-related genes (e.g., p53, caspase 3, and bax2) were significantly upregulated and the anti-apoptotic gene bcl2 was suppressed after RCS treatment. Western blotting results for Caspase 3, Bax2 and Bcl2 were consistent with the mRNA trends. These results revealed that K. mikimotoi RCS can induce neural cell apoptosis via the oxidative stress-mediated mitochondrial pathway, providing novel insights into the neurotoxicity of K. mikimotoi.
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Affiliation(s)
- Jinfang Lu
- Wenzhou Key Laboratory of Sanitary Microbiology, Key Laboratory of Laboratory Medicine, Ministry of Education, China, School of Laboratory Medicine and Life Sciences, Wenzhou Medical University, Wenzhou, Zhejiang 325035, China
| | - Xiaoqin Niu
- Wenzhou Key Laboratory of Sanitary Microbiology, Key Laboratory of Laboratory Medicine, Ministry of Education, China, School of Laboratory Medicine and Life Sciences, Wenzhou Medical University, Wenzhou, Zhejiang 325035, China; Department of Clinical Laboratory, The First Hospital of Jiaxing, The Affiliated Hospital of Jiaxing University, Jiaxing 314000, China
| | - Hong Wang
- Wenzhou Key Laboratory of Sanitary Microbiology, Key Laboratory of Laboratory Medicine, Ministry of Education, China, School of Laboratory Medicine and Life Sciences, Wenzhou Medical University, Wenzhou, Zhejiang 325035, China
| | - He Zhang
- Zhejiang Provincial Key Laboratory for Subtropical Water Environment and Marine Biological Resources Protection, National and Local Joint Engineering Research Center of Ecological Treatment Technology for Urban Water Pollution, College of Life and Environmental Sciences, Wenzhou University, Wenzhou, Zhejiang 325035, China.
| | - Wanchun Guan
- Wenzhou Key Laboratory of Sanitary Microbiology, Key Laboratory of Laboratory Medicine, Ministry of Education, China, School of Laboratory Medicine and Life Sciences, Wenzhou Medical University, Wenzhou, Zhejiang 325035, China; Institute of Marine Science, Wenzhou Medical University, Wenzhou, Zhejiang 325035, China.
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Huang K, Zhuang Y, Wang Z, Ou L, Cen J, Lu S, Qi Y. Bioavailability of Organic Phosphorus Compounds to the Harmful Dinoflagellate Karenia mikimotoi. Microorganisms 2021; 9:1961. [PMID: 34576855 PMCID: PMC8469735 DOI: 10.3390/microorganisms9091961] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2021] [Revised: 09/13/2021] [Accepted: 09/13/2021] [Indexed: 11/16/2022] Open
Abstract
Karenia mikimotoi is one of the most well-known harmful bloom species in temperate coastal waters. The present study investigated the characteristics of alkaline phosphatase (APase) and phosphodiesterase (PDEase) activities in hydrolysis of two phosphomonoesters (adenosine triphosphate (ATP) and ribulose 5-phosphate (R5P)) and a phosphodiester (cyclic adenosine monophosphate (cAMP)) in K. mikimotoi and compared its growth and physiological responses to the different forms of phosphorus substrates. K. mikimotoi produced comparable quantities of APase and PDEase to hydrolyze the organic phosphorus substrates, although hydrolysis of the phosphomonoesters was much faster than that of the phosphodiester. The growth of K. mikimotoi on organic phosphorus substrates was comparable to or better than that on inorganic phosphate. The difference in particulate organic nutrients (carbon, nitrogen, and phosphorus) and hemolytic activity supported different rates of hydrolysis-assimilation of the various organic phosphorus substrates by K. mikimotoi. The hemolytic activities of K. mikimotoi in the presence of organic phosphorus substrates were several times those in the presence of inorganic phosphate during the exponential phase. This suggested the potential important role of organic phosphorus in K. mikimotoi blooms.
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Affiliation(s)
| | | | | | - Linjian Ou
- Research Center of Harmful Algae and Marine Biology, Key Laboratory of Eutrophication and Red Tide Prevention of Guangdong Higher Education Institutes, Jinan University, Guangzhou 510632, China; (K.H.); (Y.Z.); (Z.W.); (J.C.); (S.L.); (Y.Q.)
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Li XD, Yan T, Zhang QC, Yu RC, Zhou MJ. Inhibition to crucial enzymes in the lethal effects of the dinoflagellate Karenia mikimotoi on the rotifer Brachionus plicatilis. MARINE ENVIRONMENTAL RESEARCH 2020; 157:104866. [PMID: 32275503 DOI: 10.1016/j.marenvres.2019.104866] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/22/2019] [Revised: 12/06/2019] [Accepted: 12/19/2019] [Indexed: 06/11/2023]
Abstract
Blooms of the dinoflagellate Karenia mikimotoi have cause great financial losses to the marine aquaculture industry. However, the toxicity mechanism of this species is still not fully known. In this study, we evaluated the short-term effects of K. mikimotoi on the rotifer Brachionus plicatilis by micro and sub micro observing and by measuring inhibition of crucial enzymes. Behaviour disorder, mucus production, corona and cilium damage, vesical production, and body shrinkage occurred within 1 h after rotifers were treated with K. mikimotoi at a density of 3 × 104 cells/mL. Enzyme activity assays showed that K. mikimotoi at low densities significantly inhibited multiple enzymes within 3 h, and obvious density-effect trends were also observed. For instance, activity of esterase and acetylcholinesterase of rotifers significantly decreased to 94.3/83.3% and 82.8/66.9% of control treatment values in 30 and 1000 cells/mL algal treatment, respectively. Total ATPase and Na+-K+-ATPase activities of rotifers also decreased to 82.3% and 68.6% of control values in 1000 cells/mL treatment. The LDH releasement test and MDA tests showed no significant difference between algae treatment and control. It suggested that K. mikimotoi might not cause significant cytolysis and oxidative damage to rotifers, but may cause mortality by inhibiting the activity of crucial enzymes, which may lead to cell permeability disorder and body shrinkage.
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Affiliation(s)
- Xiao-Dong Li
- Key Laboratory of Marine Biotechnology of Fujian Province, Institute of Oceanology, College of Animal Sciences, Fujian Agriculture and Forestry University, Fuzhou, Fujian, 350002, China; Key Laboratory of Marine Ecology and Environmental Sciences, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, Shandong, 266071, China; Laboratory of Marine Ecology and Environmental Science, Qingdao National Laboratory for Marine Science and Technology, Qingdao, Shandong, 266071, China.
| | - Tian Yan
- Key Laboratory of Marine Ecology and Environmental Sciences, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, Shandong, 266071, China; Laboratory of Marine Ecology and Environmental Science, Qingdao National Laboratory for Marine Science and Technology, Qingdao, Shandong, 266071, China; Centre for Ocean Mega-Science, Chinese Academy of Sciences, Qingdao, Shandong, 266071, China.
| | - Qing-Chun Zhang
- Key Laboratory of Marine Ecology and Environmental Sciences, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, Shandong, 266071, China; Laboratory of Marine Ecology and Environmental Science, Qingdao National Laboratory for Marine Science and Technology, Qingdao, Shandong, 266071, China; Centre for Ocean Mega-Science, Chinese Academy of Sciences, Qingdao, Shandong, 266071, China
| | - Ren-Cheng Yu
- Key Laboratory of Marine Ecology and Environmental Sciences, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, Shandong, 266071, China; Laboratory of Marine Ecology and Environmental Science, Qingdao National Laboratory for Marine Science and Technology, Qingdao, Shandong, 266071, China; Centre for Ocean Mega-Science, Chinese Academy of Sciences, Qingdao, Shandong, 266071, China
| | - Ming-Jiang Zhou
- Key Laboratory of Marine Ecology and Environmental Sciences, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, Shandong, 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: 53] [Impact Index Per Article: 10.6] [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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