Physiological and behavioural impacts of Pacific ciguatoxin-1 (P-CTX-1) on marine medaka (Oryzias melastigma)

Yim Ling MAK, Jing LI, Chih-Ning LIU, Shuk Han CHENG, Paul K.S. LAM, Jinping CHENG, Leo L. CHAN

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16 Citations (Scopus)


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 (2 h 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 24 h 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, 24 h after exposure. Repeated low-dose P-CTX-1 exposure resulted in larval mortality comparable to that of a single high-dose exposure. Copyright © 2016 Elsevier B.V.
Original languageEnglish
Pages (from-to)782-790
JournalJournal of Hazardous Materials
Early online date01 Oct 2016
Publication statusPublished - 05 Jan 2017


Mak, Y. L., Li, J., Liu, C.-N., Cheng, S. H., Lam, P. K. S., Cheng, J., & Chan, L. L. (2017). Physiological and behavioural impacts of Pacific ciguatoxin-1 (P-CTX-1) on marine medaka (Oryzias melastigma). Journal of Hazardous Materials, 321, 782-790. doi: 10.1016/j.jhazmat.2016.09.066


  • Ciguatoxins
  • Marine medaka
  • Locomotion
  • Behaviour
  • Cardiotoxicity


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