Possible involvement of hemolytic activity in the contact-dependent lethal effects of the dinoflagellate Karenia mikimotoi on the rotifer Brachionus plicatilis

• Published in: Harmful algae Vol. 9; no. 4; pp. 367 - 373
• Main Authors: Zou, Yanan, Yamasaki, Yasuhiro, Matsuyama, Yukihiko, Yamaguchi, Kenichi, Honjo, Tsuneo, Oda, Tatsuya
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.05.2010
• Subjects: Brachionus plicatilis; Cell contact; Hemolytic activity; Karenia mikimotoi; Marine; Reactive oxygen species; Rotifera; Toxic effect; Brachionus plicatilis; Cell contact; Reactive oxygen species; Hemolytic activity; Toxic effect; Karenia mikimotoi
• ISSN: 1568-9883; 1878-1470
• DOI: 10.1016/j.hal.2010.01.005

We investigated the effects of two strains (SUO-1 and FUK) of the dinoflagellate Karenia mikimotoi on the rotifer Brachionus plicatilis. The SUO-1 strain was highly toxic to rotifers, whereas the FUK strain was less toxic. After 10-h incubations, the survivorship of rotifers exposed to SUO-1 and FUK was 20% and 95%, respectively. Both the cell-free culture supernatant and the ruptured cell suspension prepared from these strains were not toxic to rotifers. Furthermore, when direct contact between K. mikimotoi and rotifers was interrupted with a cell-impermeable membrane (3-μm pores), the toxicity of both the SUO-1 and FUK strains of K. mikimotoi to rotifers were completely inhibited even after a 24-h exposure. Cell suspensions of SUO-1 showed hemolytic activity toward horse erythrocytes, but the FUK strain did not. The cell-free supernatant and the ruptured cell suspension of SUO-1 showed no significant hemolytic activity. These results suggest that this highly toxic strain of K. mikimotoi causes lethality in rotifers by direct contact in which live cell-mediated hemolytic activity might be a contributing factor.