No abstract

No abstract

The scuticociliate Miamiensis avidus was isolated from olive flounder Paralichthys olivaceus showing typical symptoms of ulceration and hemorrhages in skeletal muscle and fins. In an infection experiment, olive flounder (mean length: 14.9 cm; mean weight: 26.8 g) were immersion challenged with 2.0 × 10 3 , 2.0 × 10 4 and 2.0 × 10 5 ciliates ml -1 of the cloned YS1 strain of M. avidus. Cumulative mortalities were 85% in the 2.0 × 10 3 cells ml -1 treatment group and 100% in the other 2 infection groups. Many ciliates, containing red blood cells in the cytoplasm, were observed in the gills, skeletal muscle, skin, fins and brains of infected fish, which showed accompanying hemorrhagic and necrotic lesions. Ciliates were also observed in the lamina propria of the digestive tract, pharynx and cornea. The fixed ciliates were 31.5 ± 3.87 µm in length and 18.5 ± 3.04 µm in width, and were ovoid and slightly elongated in shape, with a pointed anterior and a rounded posterior, presenting a caudal cilium. Other morphological characteristics were as follows: 13 to 14 somatic kineties, oral ciliature comprising membranelles M1, M2, M3, and paroral membranes PM1 and PM2, contractile vacuole at the posterior end of kinety 2, shortened last somatic kinety and a buccal field to body length ratio of 0.47 ± 0.03. In addition, continuous PM1 and PM2, lack of M3 and variable kinetosome numbers in M2 and M3 were frequently observed. Specimens in the current study were compared with previous reports on M. avidus and Philasterides dicentrarchi and confirmed consistently that these 2 taxa are conspecific.KEY WORDS: Miamiensis avidus · Philasterides dicentrarchi · Ciliophora · Scuticociliatida · Pathogenicity · Olive flounder Resale or republication not permitted without written consent of the publisherDis Aquat Org 73: [227][228][229][230][231][232][233][234] 2007 describe, the morphometric characteristics of M. avidus cultured in Chinook salmon embryo (CHSE-214) cells and confirm M. avidus as a senior synonym for Philasterides dicentrarchi. MATERIALS AND METHODSNaturally infected fish. Wet preparations of skeletal muscle, gills and brain from Paralichthys olivaceus olive flounder showing typical symptoms of infection (ulceration and hemorrhage of skeletal muscle) were examined for the presence of ciliates. Small fish were fixed whole, in Bouin's solution; in the case of larger specimens, skeletal muscle, gills, liver, kidney, spleen, heart and brain were fixed in 10% formalin solution.Experimental infection. A cloned strain of Miamiensis avidus, YS1, was cultured for 6 d in CHSE-214 cells, then collected and centrifuged at 980 × g for 5 min. The ciliates were suspended in PBS (phosphate-buffered saline), and numbers were estimated using a hemocytometer. Olive flounder (mean total length: 14.9 cm; mean body weight: 26.8 g) were kept in an indoor tank for 2 wk prior to ciliate infection. Three groups of 20 fish were exposed to the ciliates for 45 min in 4 l of aerated water containing 2.0 × 10 3 , 2.0 × 10 4 , or 2.0 × 10 5 ...

Lymphocystis disease virus (LCDV) is the causative agent of lymphocystis disease. In this study, nucleotide sequences of the major capsid protein (MCP) gene were analyzed among LCDV isolates from Japanese flounder and rockfish. A phylogenetic tree revealed three clusters for lymphocystiviruses. The first cluster included Japanese flounder isolates; the second cluster consisted of rockfish isolates; and the remaining one consisted of LCDV-1. Nucleotide sequence identities were > or =99.6% among Japanese flounder isolates and 100% among rockfish isolates, while between each cluster they were < or =85.2%. Experimental infections with Japanese flounder and rockfish isolates revealed that Japanese flounder and rockfish were infected by the respective homologous isolate but not by the heterologous isolate. These findings suggest that at least three genotypes exist in the genus Lymphocystivirus.

Eight isolates of Miamiensis avidus (scuticociliates) were collected from olive flounder Paralichthys olivaceus with symptoms of severe ulcers and haemorrhages at several culture farms in 1999 and 2003. Cloned strains were produced and the complete small subunit ribosomal RNA gene (SSU rRNA) of each strain was sequenced for classification and phylogenic study. The SSU rRNA is 1759 bp in length and the sequence was deposited in the GenBank under accession number AY550080. All 8 strains exhibited the same sequence, but this sequence did not match any previously deposited scuticociliate SSU rRNA sequence. Phylogenetic analysis placed Miamiensis avidus in a sister lineage to Cohnilembus verminus, Pseudocohnilembus hargisi and P. marinus.