Harmful effects of Dinophysis to the ciliate Mesodinium rubrum: Implications for prey capture.

Autor: Mafra LL Jr; Centro de Estudos do Mar, Universidade Federal do Paraná, Cx. Postal 61, Pontal do Paraná, Paraná, 83255-976, Brazil. Electronic address: luiz.mafra@ufpr.br., Nagai S; National Research Institute of Fisheries Science, 2-14-4 Fukuura, Kanazawa, Yokohama, Kanagawa, 236-8648, Japan. Electronic address: snagai@affrc.go.jp., Uchida H; National Research Institute of Fisheries Science, 2-14-4 Fukuura, Kanazawa, Yokohama, Kanagawa, 236-8648, Japan. Electronic address: huchida@affrc.go.jp., Tavares CP; Centro de Estudos do Mar, Universidade Federal do Paraná, Cx. Postal 61, Pontal do Paraná, Paraná, 83255-976, Brazil. Electronic address: camilapstavares@gmail.com., Escobar BP; Centro de Estudos do Mar, Universidade Federal do Paraná, Cx. Postal 61, Pontal do Paraná, Paraná, 83255-976, Brazil. Electronic address: bruno.p.escobar@hotmail.com., Suzuki T; National Research Institute of Fisheries Science, 2-14-4 Fukuura, Kanazawa, Yokohama, Kanagawa, 236-8648, Japan. Electronic address: tsuzuki@affrc.go.jp.
Jazyk: angličtina
Zdroj: Harmful algae [Harmful Algae] 2016 Nov; Vol. 59, pp. 82-90. Date of Electronic Publication: 2016 Oct 07.
DOI: 10.1016/j.hal.2016.09.009
Abstrakt: Toxigenic Dinophysis spp. are obligate mixotrophic dinoflagellates that require a constant supply of prey-Mesodinium rubrum-to achieve long-term growth by means of kleptoplasty. Mesodinium rubrum is, however, a fast moving, jumping ciliate exhibiting an effective escape response from suspensivorous predators. In the present study, a series of laboratory experiments evaluating the motility and survival of M. rubrum in the presence of Dinophysis cells and/or substances contained in their culture medium was designed, in order to assess the mechanisms involved in prey capture by Dinophysis spp. Cell abundance of M. rubrum decreased in the presence of Dinophysis cf. ovum cells producing okadaic acid (OA; up to 7.94±2.67pgcell -1 ) and smaller amounts of dinophysistoxin-1 (DTX-1) and pectenotoxin-2 (PTX-2). Prey capture was often observed after the ciliate had been attached to adhesive "mucus traps", which only appeared in the presence of Dinophysis cells. Before being attached to the mucus traps, M. rubrum cells reduced significantly their swimming frequency (from ∼41 to 19±3 jumps min -1 ) after only 4h of initial contact with D. cf. ovum cells. M. rubrum survival was not affected in contact with purified OA, DTX-1 and PTX-2 solutions, but decreased significantly when the ciliate was exposed to cell-free or filtered culture medium from both D. cf. ovum and D. caudata, the latter containing moderate concentrations of free eicosapentaenoic acid and docosahexaenoic acid. The results thus indicate that Dinophysis combines the release of toxic compounds other than shellfish toxins, possibly free PUFAs, and a "mucus trap" to enhance its prey capture success by immobilizing and subsequently arresting M. rubrum cells.
(Copyright © 2016 Elsevier B.V. All rights reserved.)
Databáze: MEDLINE
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