X-cells in fish pseudotumors are parasitic protozoans

Diseases of Aquatic Organisms

Chihaya Nakayasu¹  Satoshi Miwa¹  Takashi Kamaishi¹  Yasutoshi Yoshiura¹ 

关键词: X-cell;    18S rRNA;    In situ hybridization;    Protozoa;    Hippoglossoides dubius;    Fishes;    Pseudotumor;   

DOI  :  10.3354/dao058165

学科分类：生物科学（综合）

来源: Inter-Research

【 摘 要 】

ABSTRACT: Bottom-dwelling teleosts, particularly flatfishes or cod living in temperate to cold seawater, sometimes develop tumor-like lesions on the body surface or in the branchial cavity. These lesions usually contain masses of so called ŒX-cells¹of unknown origin. We amplified a gene for small subunit ribosomal RNA (18S rRNA) from X-cell lesions of the flathead flounder Hippoglossoides dubius. Phylogenetic analysis clearly classified the obtained sequence as a protozoan, although theorganism had no clear affinity with any known protistan groups. In situ hybridization showed that probes specific for the protozoan 18S rRNA hybridized only with X-cells, and not with the host-fish cells, indicating that X-cells harbor theprotozoan rRNA. On the other hand, a probe specific for vertebrate 18S rRNA hybridized with the host-fish cells, but not with X-cells. This is conclusive evidence that X-cells are parasitic protozoans.

【 授权许可】

Unknown