Encystment and excystment of kinetoplastid Azumiobodo hoyamushi, causal agent of soft tunic syndrome in ascidian aquaculture

Diseases of Aquatic Organisms

Euichi Hirose¹  Shin-Ichi Kitamura¹  Akatsuki Nawata¹  Akira Kumagai¹ 

关键词: Kinetoplastid flagellate;    Halocynthia roretzi;    Soft tunic syndrome;    Tunic extract;    Temporary cyst;    In vitro culture;    pH;   

DOI  :  10.3354/dao02897

学科分类：生物科学（综合）

来源: Inter-Research

【 摘 要 】

ABSTRACT: Soft tunic syndrome in the edible ascidian Halocynthia roretzi is caused by the kinetoplastid flagellate Azumiobodo hoyamushi, which was found to assume a fusiform cell form with 2 flagella in axenic, pure culture. When the flagellate form was incubated in sterilized artificial seawater (pH 8.4), some of the cells became cyst-like and adhered to the bottom of the culture plate. The cyst-like forms were spherical or cuboidal, and each had 2 flagella encapsulated in its cytoplasm. Encystment was also induced in culture medium alkalified to the pH of seawater (8.4) but not in unmodified (pH 7.2) or acidified media (pH 6.4). More than 95% of the cyst-like cells converted to the flagellate form within 1 d following transfer to seawater containing ascidian tunic extracts from host ascidians. The cyst-like cells were able to survive in seawater with no added nutrients for up to 2 wk at 20°C and for a few months at 5 to 15°C. The survival period in seawater depended on temperature: some cyst-like cells survived 3 mo at 10°C, and ca. 95% of these converted to flagellate forms in seawater containing tunic extracts. Thus, A. hoyamushi is able to persist under adverse conditions in a cyst-like form able to adhere to organic and inorganic substrata for protracted periods of time.

【 授权许可】

Unknown