Shin-ichi Ono

Novel DNA virus isolated from samples showing endothelial cell necrosis in the Japanese eel, Anguilla japonica

Economic loss due to viral endothelial cell necrosis of eel (VECNE) of Anguilla japonica is a serious problem for the cultured Japanese eel market. However, the viral genome responsible for VECNE is unknown. We recently developed a rapid determination system for viral nucleic acid sequences (RDV) to determine viral genome sequences. In this study, viral DNA fragments were obtained using RDV, and approximately 15-kbp circular full genome sequences were determined using a next-generation sequencing system, overlapping PCR, and Southern blot analysis. One open reading frame (ORF) was homologous to the large T-antigen of polyomavirus; other ORFs have no homology with any nucleic or amino acid sequences of polyomavirus. Therefore, as this DNA virus might comprise a novel virus family, we provisionally named it Japanese eel endothelial cells-infecting virus (JEECV). JEECV was detected in both naturally and experimentally infected eels, suggesting that JEECV potentially causes VECNE.

Identification, characterization and full-length sequence analysis of a novel dsRNA virus isolated from the arboreal ant Camponotus yamaokai.

A novel dsRNA virus was identified from the arboreal ant Camponotus yamaokai. The complete nucleotide sequence analysis of the virus revealed that the virus consisted of 5704 bp with two ORFs. ORF1 (3084 nt) encoded a putative capsid protein. ORF2 (1977 nt) encoded a viral RNA-dependent RNA polymerase (RdRp). ORF2 could be translated as a fusion with the ORF1 product by a - 1 frameshift in the overlapping ORF1. Phylogenetic analyses based on the RdRp revealed that the virus from C. yamaokai was most likely a novel totivirus, but it was not closely related to the previously known totiviruses in arthropods. Transmission electron microscopy revealed isometric virus particles of ~30 nm diameter in the cytoplasm, which was consistent with the characteristics of the family Totiviridae. The virus was detected by reverse transcription-PCR in all caste members and developmental stages of ants, including eggs, larvae, pupae, adult workers, alates (male and female) and queens. To our knowledge, this is the first report of a member of the family Totiviridae in a hymenopteran; the virus was designated Camponotus yamaokai virus.

Detection of Japanese eel endothelial cells-infecting virus in Anguilla japonica elvers.

Japanese eel endothelial cells-infecting virus (JEECV) has spread in eel farms and caused serious economic loss. In this study, we examined the prevalence of JEECV infection in 100 wild Japanese eel (Anguilla japonica) elvers caught from Yamaguchi prefecture, Japan, using quantitative PCR and conventional PCR. Total genomic DNA was obtained from the cranial quarter of the body in 70 of 100 eels and from the gill in the remaining. Of 30 gill samples, 20 were analyzed after pooling with other samples, and the remaining 10 were analyzed separately. A single positive result for JEECV was detected following analysis of the 10 separately analyzed samples. This result constitutes the first report of JEECV infection in wild A. japonica elvers.

Complete Genome Sequences of Two Japanese Eel Endothelial Cell-Infecting Virus Strains Isolated in Japan.

ABSTRACT Japanese eel endothelial cell-infecting virus (JEECV) causes viral endothelial cell necrosis of eel (VECNE), resulting in severe economic losses in eel aquaculture in Japan. Here, we report the complete genome sequences of two new JEECV strains isolated from farmed Japanese eels.

Microbially Mediated Growth Process of Manganese Oxides.

マンガン酸化バクテリアの媒介によってマンガン酸化物が沈殿している東海大学海洋科学博物館の地下海水給水系に, スライド・ガラスを多数設置し, その上に付着するマンガン酸化バクテリアおよび酸化物を時系列的に調べ, マンガン酸化物の成長過程の形態学的および化学的研究を行った。最初, バクテリアがばらばらにスライドガラスに付着し, その後集菌する。それらは集塊状になった後溶菌する。溶菌と共にマンガン酸化物が沈殿を開始し, ドーナツ状, ドーム状を経て, カリフラワー状に成長する。ドーナツ状になった段階で, 酸化物表面に, マンガン酸塩(manganate)特有の蜂の巣状構造が現れる。マンガン酸化物の成長速度は1.8×10-2mmyr-1であり, Mn(II)の酸化速度定数(kMn)は, kMn=6×1019mol-4l4d-1であった。マンガン酸化物中のCoおよびNiの濃度は, 沈殿後取り込み現象(post-depositional uptake)により, 時間と共に増加するが, Cuにはこの傾向は見られなかった。