title: Respiratory toxicity of cyanobacterial aphantoxins from Aphanizomenon flos-aquae DC-1 in the zebrafish gill.
abstract: Aphantoxins from Aphanizomenon flos-aquae are frequently identified in eutrophic waterbodies worldwide. These toxins severely endanger environmental safety and human health due to the production of paralytic shellfish poisons (PSPs). Although the molecular mechanisms of aphantoxin neurotoxicity have been studied, many questions remain to be resolved such as in vivo alterations in branchial histology and neurotransmitter inactivation induced by these neurotoxins. Aphantoxins extracted from a naturally isolated strain of A. flos-aquae DC-1 were determined by high performance liquid chromatography. The basic components of the isolated aphantoxins identified were gonyautoxin 1 (GTX1), gonyautoxin 5 (GTX5), and neosaxitoxin (neoSTX), which comprised 34.04, 21.28, and 12.77% of the total, respectively. Zebrafish (Danio rerio) was administrated 5.3 or 7.61mg STX equivalents (eq)/kg (low and high doses, respectively) of the A. flos-aquae DC-1 aphantoxins by intraperitoneal injection. Histological alterations and changes in neurotransmitter inactivation in the gills of zebrafish were investigated for 24h following exposure. Aphantoxin exposure significantly increased the activities of gill alanine aminotransferase (ALT) and aspartate aminotransferase (AST) and resulted in histological alterations in the gills during the first 12h of exposure, indicating the induction of functional and structural damage. Gill acetylcholinesterase (AChE) and monoamine oxidase (MAO) activities were inhibited significantly, suggesting an alteration of neurotransmitter inactivation in zebrafish gills. The observed alterations in gill structure and function followed a time- and dose-dependent pattern. The results demonstrate that aphantoxins or PSPs lead to structural damage and altered function in the gills of zebrafish, including changes in histological structure and increases in the activities of AST and ALT. The inhibition of the activities of AChE and MAO suggest that aphantoxins or PSPs could induce respiratory toxicity in the zebrafish gill. Furthermore, these parameters may be used as bioindicators for investigating aphantoxin exposure and cyanobacterial blooms in nature.
authors.affiliation: Department of Lifescience and Biotechnology, College of Chemistry, Chemical Engineering and Life Sciences, Wuhan University of Technology, Wuhan 430070, PR China. Electronic address: deluzh@163.com.
authors.forename: De Lu
authors.initials: de L
authors.lastname: Zhang
authors.affiliation: Department of Lifescience and Biotechnology, College of Chemistry, Chemical Engineering and Life Sciences, Wuhan University of Technology, Wuhan 430070, PR China.
authors.forename: Si Yi
authors.initials: SY
authors.lastname: Liu
authors.affiliation: College of Chemistry and Molecular Sciences, Wuhan University, Wuhan 430072, PR China.
authors.forename: Jing
authors.initials: J
authors.lastname: Zhang
authors.affiliation: Department of Lifescience and Biotechnology, College of Chemistry, Chemical Engineering and Life Sciences, Wuhan University of Technology, Wuhan 430070, PR China.
authors.forename: Jian Kun
authors.initials: JK
authors.lastname: Zhang
authors.affiliation: Key Laboratory of Algal Biology, Institute of Hydrobiology, The Chinese Academy of Sciences, Wuhan 430072, PR China. Electronic address: cxhu@ihb.ac.cn.
authors.forename: Chun Xiang
authors.initials: CX
authors.lastname: Hu
authors.affiliation: Key Laboratory of Algal Biology, Institute of Hydrobiology, The Chinese Academy of Sciences, Wuhan 430072, PR China.
authors.forename: Yong Ding
authors.initials: YD
authors.lastname: Liu
mesh_terms: D000110:Acetylcholinesterase / Q000378:metabolism; D000410:Alanine Transaminase / Q000378:metabolism; D000818:Animals; D046890:Aphanizomenon; D001219:Aspartate Aminotransferases / Q000378:metabolism; D001427:Bacterial Toxins / Q000633:toxicity*; D002851:Chromatography, High Pressure Liquid; D005880:Gills / Q000187:drug effects* / Q000201:enzymology / Q000473:pathology; D008387:Marine Toxins / Q000633:toxicity*; D008995:Monoamine Oxidase / Q000378:metabolism; D012143:Respiratory Physiological Phenomena / Q000187:drug effects; D012530:Saxitoxin / Q000031:analogs & derivatives* / Q000633:toxicity; D014874:Water Pollutants, Chemical / Q000633:toxicity*; D015027:Zebrafish
chemical_list: D001427:Bacterial Toxins; D008387:Marine Toxins; D014874:Water Pollutants, Chemical; D012530:Saxitoxin; C034902:neosaxitoxin; C034321:aphantoxin; C013007:gonyautoxins; D008995:Monoamine Oxidase; D001219:Aspartate Aminotransferases; D000410:Alanine Transaminase; D000110:Acetylcholinesterase
keywords: AChE; Aphantoxins; Histological alteration; MAO; Respiratory toxicity; Zebrafish gill