Ryo Hoshina

Ryo Hoshina
Ritsumeikan University · Department of Biomedical Sciences

About

80
Publications
11,028
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515
Citations
Citations since 2016
11 Research Items
258 Citations
2016201720182019202020212022020406080
2016201720182019202020212022020406080
2016201720182019202020212022020406080
2016201720182019202020212022020406080
Introduction
Skills and Expertise
Additional affiliations
January 2013 - present
Nagahama Institute of Bio-Science and Technology
Position
  • josyu

Publications

Publications (80)
Preprint
Full-text available
Background: Photosynthetic eukaryotes have evolved through the acquisition of plastids by secondary endosymbiosis, a process that requires several steps. Immediately before plastid acquisition, the genome of the symbiont is known to be dramatically reduced, but few studies have focused on the genomic changes in the symbiont at the early stages of s...
Preprint
Full-text available
Background: Photosynthetic eukaryotes have evolved through the acquisition of plastids by secondary endosymbiosis, a process that requires several steps. Immediately before plastid acquisition, the genome of the symbiont is known to be dramatically reduced, but few studies have focused on the genomic changes in the symbiont at the early stages of s...
Article
Full-text available
The genus Stentor is a relatively well-known ciliate owing to its lucid trumpet shape. Stentor pyriformis represents a green, short, and fat Stentor , but it is a little-known species. We investigated 124 ponds and wetlands in Japan and confirmed the presence of S. pyriformis at 23 locations. All these ponds were noticeably oligotrophic. With the i...
Article
Full-text available
Freshwater protists often harbor unicellular green algae within their cells. In ciliates, possibly because of large host cell sizes and the small size of algal coccoids, a single host cell typically contains more than a hundred algal cells. While surveying such algae-bearing protists on Minami Daito Jima Island in Japan, we found a green Loxodes ci...
Article
Full-text available
Background: The plastid acquisition by secondary endosymbiosis is a driving force for the algal evolution, and the comparative genomics was required to examine the genomic change of symbiont. Therefore, we established a pipeline of a de novo assembly of middle-sized genomes at a low cost and with high quality using long and short reads. Results:...
Article
Full-text available
Chlorella variabilis, a symbiotic alga, is usually present in the cytoplasm of Paramecium bursaria, although it can be cultured in host-free conditions. Morphological and chemical properties of its cell wall were compared between its free-living and symbiotic states. Transmission electron microscopy (quick-freezing and freeze-substitution methods)...
Article
Recently, the genus name Brandtia Hoshina was given for a chlorellacean symbiotic alga residing in some ciliate species. However, it was found that Brandtia Hoshina 2017 is an illegitimate later homonym of Brandtia Kunth 1831. Therefore, a replacement name, Carolibrandtia nom. nov., for Brandtia Hoshina is here proposed.
Article
Many freshwater protists harbor unicellular green algae within their cells and these host-symbiont relationships slowly are becoming better understood. Recently, we reported that several ciliate species shared a single species of symbiotic algae. Nonetheless, the algae from different host ciliates were each distinguishable by their different genoty...
Article
Many freshwater protists harbor unicellular green algae within their cells, but little is known of their degree of integration and specificity. Using algae-targeted PCR of whole ciliate cells collected at irregular intervals over 15 months from Lake Biwa, Japan, we explored the SSU-ITS rDNA of the endosymbiotic algae and its changes over time, obta...
Article
Full-text available
Background DNA comparison is becoming the leading approach to the analysis of microbial diversity. For eukaryotes, the internal transcribed spacer 2 (ITS2) has emerged as a conspicuous molecule that is useful for distinguishing between species. Because of the small number of usable ITS data in GenBank, ITS2 sequence comparisons have only been used...
Article
Full-text available
The photobiont-containing ciliate, Paramecium bursaria, was cultured for a week under three treatments: 25A degrees C with light (25 L), 10A degrees C without light (10 D), and 10A degrees C with light (10 L). Cells of two strains under the 10 D treatment were enlarged relative to those under the 25 L treatment. This effect was very pronounced in t...
Article
Chlorella Beijerinck (Chlorellaceae, Trebouxiophyceae) strains from the collection of the National Institute for Environmental Studies (NIES) were characterized using gene sequence data. The misidentification of a number of strains was rectified. Chlorella vulgaris Beijerinck NIES-2173 was reclassified as C. sorokiniana Shihira et Krauss. Chlorella...
Article
Stentor polymorphus (Müller) Ehrenberg (Heterotrichea, Ciliophora) is a trumpet-form ciliate with endosymbiotic green algae (photobionts). Previous reports have indicated that this photobiont has a form typical of Chlorella Beijerinck (Trebouxiophyceae), with one chloroplast and a distinct pyrenoid. We collected S. polymorphus from an artificial po...
Article
Full-text available
The green ciliate, Paramecium bursaria, has evolved a mutualistic relationship with endosymbiotic green algae (photo-bionts). Under culture conditions, photobionts are usually unified (to be single species) within each P. bursaria strain. In most cases, the algal partners are restricted to either Chlorella variabilis or Micractinium reisseri (Chlor...
Article
Full-text available
The intronic sequence intervening the small subunit ribosomal DNA (SSU rDNA) of Chlorella sp. T-24-5, an atypical photobiont of Paramecium bursaria was examined. The position of the insertion was found to be 10 nucleotides upstream from that of a major P. bursaria photobiont, Micractinium reisseri (S651), and was found to be a novel insertion site...
Article
Micractinium reisseri Hoshina, Iwataki et Imamura (Chlorellaceae, Trebouxiophyceae), an alga symbiotic with the ciliate Paramecium bursaria (Ehrenberg) Focker, was recently renamed M. conductrix (K. Brandt) Pröschold et Darienko. The name ‘conductrix’ was originally given to an algal endosymbiont of Hydra, a genus of Hydrozoa. Here, I outline key d...
Article
Micractinium reisseri Hoshina, Iwataki et Imamura (Chlorellaceae, Trebouxiophyceae), an alga symbiotic with the ciliate Paramecium bursaria (Ehrenberg) Focker, was recently renamed M. conductrix (K. Brandt) Pröschold et Darienko. The name ‘conductrix’ was originally given to an algal endosymbiont of Hydra, a genus of Hydrozoa. Here, I outline key d...
Article
The nuclear ribosomal RNA gene operon is interrupted by internal transcribed spacer (ITS) 1 and ITS2. Although the secondary structure of ITS2 has been widely investigated, less is known about ITS1 and its structure. In this study, the secondary structure of ITS1 sequences for Paramecium and other ciliates was predicted. Each Paramecium ITS1 forms...
Article
Full-text available
We performed an environmental study of viruses infecting the symbiotic single-celled algae of Paramecium bursaria (Paramecium bursaria Chlorella virus, PBCV) in Lake Biwa, the largest lake in Japan. The viruses detected were all Chlorella variabilis virus (CvV = NC64A virus). One of them, designated CvV-BW1, was subjected to further characterizatio...
Article
Symbiotic algae of the ciliate Paramecium bursaria (Ehrenberg) Focker are key species in the fields of virology and molecular evolutionary biology as well as in the biology of symbiotic relationships. These symbiotic algae were once identified as Zoochlorella conductrix Brandt by the Dutch microbiologist, Beijerinck 120 years ago. However, after ma...
Chapter
The green paramecium, Paramecium bursaria, has evolved a mutualistic relationship with green algae that has fascinated microbiologists for over a century. Classical approaches to determining the identities of these algae have indicated that the symbionts are close relatives of the genus Chlorella, in which two differentiable algal groups, the “Amer...
Article
Group I introns are a distinct RNA group that catalyze their excision from precursor RNA transcripts and ligate the exons. Group I introns have a sporadic and highly biased distribution due to the two intron transfer mechanisms of homing and reverse splicing. These transfer pathways recognize assigned sequences even when introns are transferred bey...
Article
Paramecium bursaria, a species belonging to the genus Paramecium, is quite unique in that the species intracellularly maintains several hundreds of symbiotic algae. This species has been regarded as firstly branched-off species within this genus, and reported its higher genetic variation. We determined rDNA 5 ’ half regions of 13 strains of P. burs...
Article
Although the examination of large subunit ribosomal RNA genes (LSU rDNA) is advanced in phylogenetic studies, no corresponding sequence data from trebouxiophytes have been published, with the exception of ‘Chlorella’ellipsoidea Gerneck. We determined the LSU rDNA sequence of Chlorella vulgaris Beijerinck and of the symbiotic alga of green parameciu...
Article
Many organisms have symbioses with photosynthetic algae as typified by corals, clams, lichens, and some protozoa. Paramecium bursaria contains green algal symbionts and this unicellular ciliate is a textbook example used for microscopic observation in junior high school science projects. We have determined molecular phylogenies for the green algal...
Article
Paramecium bursaria, a species belonging to the genus Paramecium, is quite unique in that the species intracellularly maintains several hundreds of symbiotic algae. This species has been regarded as firstly branched-off species within this genus, and reported its higher genetic variation. We determined rDNA 5' half regions of 13 strains of P. bursa...
Article
SUMMARY Endosymbiotic algae of Japanese Paramecium bur- saria were isolated and their axenicity was finally con- firmed by DGGE method. Japanese symbiotic strains (F36- ZK and others) and American one, NC64A from ATCC, could use ammonia and organic nitrogen but not nitrate or nitrite as a sole nitrogen source. The measurement of nitrate (NR) reduct...
Article
Paramecium bursaria is composed of a "host" ciliate and a "symbiont" green alga. Based upon physiology, DNA hybridization and virus infection, two types of symbionts, called "American" type and "European" type, have been reported to date. Here, we determined the 18S rDNA and internal transcribed spacer 2 (ITS2) regions for both "American" and "Euro...
Article
Cells of the green paramecium, Paramecium bursaria, contain several hundred endosymbiont cells. The properties of the symbionts are considered to vary depending on the collection site of the host. Difficulties in achieving axenic cells and maintenance of axenic strains for long periods have been reported for symbiotic algae from P. bursaria isolate...
Article
In the nuclear encoded small subunit ribosomal DNA (18S rDNA) of symbiotic alga of Paramecium bursaria (F36 collected in Japan) possesses three intron‐like insertions (Hoshina et al., unpubl. data, 2003). The present study confirmed these exact lengths and insertion sites by reverse transcription‐PCR. Two of them were inserted at Escherichia coli...
Article
Endosymbiotic green algae of Japanese Paramecium bursaria were phylogenetically analyzed based on DNA sequences from the ribosomal DNA operon (18S rDNA, ITS1, 5.8S rDNA, and ITS2). Phylogenetic trees constructed using 18S rDNA sequences showed that the symbionts belong to the Chlorella sensu stricto (Trebouxiophyceae) group. They are genetically cl...

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