title: Physiological and behavioural impacts of Pacific ciguatoxin-1 (P-CTX-1) on marine medaka (Oryzias melastigma).
abstract: Ciguatoxins (CTXs) are natural biotoxins produced by benthic dinoflagellates of the genus Gambierdiscus, which are bioaccumulated and biotransformed along food chains in coral ecosystems. They are neurotoxins that activate voltage-gated sodium channels and disrupt ion conductance in the excitable tissues. Pacific ciguatoxin-1 (P-CTX-1) is the most prevalent and potent CTX congener present in fishes from the Pacific Ocean. In this study, P-CTX-1 was administrated to larval marine medaka (2h post-hatch) via microinjection. Exposure to P-CTX-1 at sub-ppb levels led to adverse behavioural changes, altered physiological performances and reduced survivability of the larval marine medaka as early as 24h after exposure. P-CTX-1 decreased the rate of heartbeat and locomotion of the exposed larvae, probably owing to a series of physiological processes and morphological changes such as pericardial oedema, failure of swim bladder inflation and spinal curvature. The exposed larval marine medaka also demonstrated reduced, delayed and paralyzed responses to external stimulations. This may render them more susceptible to predation. P-CTX-1 could be effectively distributed from the yolk sac to all parts of the fish body, including head and trunk, 24h after exposure. Repeated low-dose P-CTX-1 exposure resulted in larval mortality comparable to that of a single high-dose exposure.
authors.affiliation: State Key Laboratory in Marine Pollution, City University of Hong Kong, Tat Chee Avenue, Kowloon Tong, Hong Kong Special Administrative Region; 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.
authors.forename: Yim Ling
authors.initials: YL
authors.lastname: Mak
authors.affiliation: 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.
authors.forename: Jing
authors.initials: J
authors.lastname: Li
authors.affiliation: State Key Laboratory in Marine Pollution, City University of Hong Kong, Tat Chee Avenue, Kowloon Tong, Hong Kong Special Administrative Region; 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.
authors.forename: Chih-Ning
authors.initials: CN
authors.lastname: Liu
authors.affiliation: State Key Laboratory in Marine Pollution, City University of Hong Kong, Tat Chee Avenue, Kowloon Tong, Hong Kong Special Administrative Region; Department of Biomedical Sciences, City University of Hong Kong, Tat Chee Avenue, Kowloon Tong, Hong Kong Special Administrative Region.
authors.forename: Shuk Han
authors.initials: SH
authors.lastname: Cheng
authors.affiliation: State Key Laboratory in Marine Pollution, City University of Hong Kong, Tat Chee Avenue, Kowloon Tong, Hong Kong Special Administrative Region; 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; Department of Biology and Chemistry, City University of Hong Kong, Tat Chee Avenue, Kowloon Tong, Hong Kong Special Administrative Region.
authors.forename: Paul K S
authors.initials: PKS
authors.lastname: Lam
authors.affiliation: Environmental Science Programs, School of Science, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong Special Administrative Region. Electronic address: jinpingcheng@gmail.com.
authors.forename: Jinping
authors.initials: J
authors.lastname: Cheng
authors.affiliation: State Key Laboratory in Marine Pollution, City University of Hong Kong, Tat Chee Avenue, Kowloon Tong, Hong Kong Special Administrative Region; 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; Department of Biomedical Sciences, City University of Hong Kong, Tat Chee Avenue, Kowloon Tong, Hong Kong Special Administrative Region. Electronic address: leochan@cityu.edu.hk.
authors.forename: Leo L
authors.initials: LL
authors.lastname: Chan
mesh_terms: D000014:Abnormalities, Drug-Induced / Q000473:pathology; D000818:Animals; D001522:Behavior, Animal / Q000187:drug effects*; D002922:Ciguatoxins / Q000493:pharmacokinetics / Q000633:toxicity*; D006339:Heart Rate / Q000187:drug effects; D007814:Larva; D008845:Microinjections; D009043:Motor Activity / Q000187:drug effects; D009498:Neurotoxins / Q000493:pharmacokinetics / Q000633:toxicity*; D009990:Oryzias; D016019:Survival Analysis; D014018:Tissue Distribution
chemical_list: D009498:Neurotoxins; D002922:Ciguatoxins
keywords: Behaviour; Cardiotoxicity; Ciguatoxins; Locomotion; Marine medaka