A rickettsial endosymbiont inhabiting the cytoplasm of <i>Volvox carteri</i> (Volvocales, Chlorophyceae)

Kawafune, Kaoru; Hongoh, Yuichi; Nozaki, Hisayoshi

doi:10.2216/13-193.1

Cited by 13 publications

(32 citation statements)

References 26 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Rickettsial symbionts were also found living inside phototrophic host eukaryotes, including strains of three volvocalean green algae: Carteria cerasiformis , Pleodorina japonica , and Volvox carteri (Kawafune et al. , ).…”

Section: Discussionmentioning

confidence: 99%

“…Among protists, ciliates (Alveolata), amoebozoans (Amoebozoa), haplosporidians (Rhizaria), and euglenids (Excavata) are known to associate with rickettsial symbionts (Fritsche et al 1999, Beier et al 2002, Hine et al 2002, Kim et al 2010, Vannini et al 2010, Dziallas et al 2012. Rickettsial symbionts were also found living inside phototrophic host eukaryotes, including strains of three volvocalean green algae: Carteria cerasiformis, Pleodorina japonica, and Volvox carteri (Kawafune et al 2012(Kawafune et al , 2014.…”

Section: Discussionmentioning

confidence: 99%

“…) and eveFC‐5′/enRG‐3′ (Kawafune et al. , ). When amplification was positive, the corresponding PCR product was cleaned up and directly sequenced in both directions.…”

Section: Methodsmentioning

confidence: 99%

“…To screen for the presence or absence of rickettsial endosymbiont in three strains of M. viride (NIES-296, NIES-475, and SAG50-1), PCR amplification was performed using two sets of primers that target specifically the family Rickettsiaceae. These include N577enFE-5 0 /N577enRG-3 0 (Kawafune et al 2012) and eveFC-5 0 /enRG-3 0 (Kawafune et al 2012(Kawafune et al , 2014. When amplification was positive, the corresponding PCR product was cleaned up and directly sequenced in both directions.…”

Section: Methodsmentioning

confidence: 99%

See 3 more Smart Citations

Rickettsial endosymbiont in the “early‐diverging” streptophyte green alga Mesostigma viride

Yang

Narechania

Kim

2016

Journal of Phycology

View full text Add to dashboard Cite

A bacterial endosymbiont was unexpectedly found in the "axenic" culture strain of the streptophyte green alga Mesostigma viride (NIES-995). Phylogenetic analyses based on 16S rRNA gene sequences showed that the symbiont belongs to the order Rickettsiales, specifically to the recently designated clade "Candidatus Megaira," which is closely related to the well-known Rickettsia clade. Rickettsiales bacteria of the "Ca. Megaira" clade are found in a taxonomically diverse array of eukaryotic hosts, including chlorophycean green algae, several ciliate species, and invertebrates such as Hydra. Transmission electron microscopy, fluorescence in situ hybridi-zation, and SYBR Green I staining experiments revealed that the endosymbiont of M. viride NIES-995 is rod shaped, typically occurs in clusters, and is surrounded by a halo-like structure, presumably formed by secretory substances from the bacterium. Two additional M. viride strains (NIES-296 and NIES-475), but not SAG50-1, were found to house the rickettsial endosymbiont. Analyses of strain NIES-995 transcriptome data indicated the presence of at least 91 transcriptionally active genes of symbiont origins. These include genes for surface proteins (e.g., rOmpB) that are known to play key roles in bacterial attachment onto host eukaryotes in related Rickettsia species. The assembled M. viride transcriptome includes transcripts that code for a suite of predicted algal-derived proteins, such as Ku70, WASH, SCAR, and CDC42, which may be important in the formation of the algal-rickettsial association.

show abstract

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

“…) and eveFC‐5′/enRG‐3′ (Kawafune et al. , ). When amplification was positive, the corresponding PCR product was cleaned up and directly sequenced in both directions.…”

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

See 2 more Smart Citations

Rickettsial endosymbiont in the “early‐diverging” streptophyte green alga Mesostigma viride

Yang

Narechania

Kim

2016

Journal of Phycology

View full text Add to dashboard Cite

show abstract

“…A Rickettsia species was found in the cytoplasm of the naked, filose amoeba Nuclearia pattersonii (Nucleariidae, Opisthokonta) (73), and representatives of the "Ca. Megaira" clade (Rickettsiaceae) colonize volvocalean green algae such as Carteria, Pleodorina, and Volvox (Chlorophyta, Viridiplantae) (74)(75)(76). There is also one report on "Ca.…”

Section: Phylogenetic Identity and Taxonomy Of "Candidatus Finniella"mentioning

confidence: 99%

“Candidatus Finniella” (Rickettsiales, Alphaproteobacteria), Novel Endosymbionts of Viridiraptorid Amoeboflagellates (Cercozoa, Rhizaria)

Hess

Suthaus

Melkonian

2016

Appl Environ Microbiol

View full text Add to dashboard Cite

The Rickettsiales (Alphaproteobacteria) are obligate intracellular bacteria that colonize a wide range of eukaryotic hosts, including diverse metazoa and protists. Here, we characterize rickettsial endosymbionts discovered in the cytoplasm of the algivorous amoeboflagellates Viridiraptor invadens and Orciraptor agilis (Viridiraptoridae, Cercozoa, Rhizaria), supplying evidence of free-living, phagotrophic members of the Cercozoa serving as hosts for Rickettsiales. According to 16S rRNA gene phylogenies, the bacteria represent two closely related but distinct genotypes within a deep-branching rickettsial clade, which contains the genera "Candidatus Odyssella," "Candidatus Paracaedibacter," and "Candidatus Captivus." Using the full-cycle rRNA approach, we detected the novel bacteria in four of nine viridiraptorid strains tested. Furthermore, two specific oligonucleotide probes with a single-nucleotide-difference discriminated both bacterial genotypes by fluorescence in situ hybridization (FISH). We establish the candidate species "Candidatus Finniella inopinata" (found in Viridiraptor invadens) and "Candidatus Finniella lucida" (found in Orciraptor agilis) for the novel bacteria and propose a new, provisional family of Rickettsiales, "Candidatus Paracaedibacteraceae." T he family Viridiraptoridae (Cercozoa, Rhizaria) comprises amoeboflagellates that perforate the cell walls of freshwater green algae (Viridiplantae) and feed on the algal cell contents by phagocytosis (1). During the ultrastructural investigation of Viridiraptor invadens, we observed intracellular bacteria that were scattered throughout the cytoplasm and not enclosed in a vacuolar membrane (2). Besides these ultrastructural features, the strictly algivorous diet of Viridiraptor and the axenic culture conditions excluded the possibility of engulfed food bacteria and instead suggested that Viridiraptor was colonized by endosymbionts. Singlecelled eukaryotes (protists) of diverse phylogenetic affiliations are known to harbor bacterial endosymbionts and therefore represent an almost ubiquitous, natural reservoir for facultative and obligate intracellular bacteria (3-5). The bacteria colonizing eukaryotic cells are equally diverse, and a broad spectrum of interaction exists, ranging from mutualism and balanced parasitism to pathogenic situations that involve host cell lysis (5). Protists have even been suggested to serve as vectors and training grounds for pathogenic bacteria (6). They are frequently colonized by representatives of the eubacterial orders Chlamydiales (Chlamydiae), Legionellales (Gammaproteobacteria), and Rickettsiales (Alphaproteobacteria), whose members are linked to severe diseases in mammals, including humans (7-9).Compared to other protist groups, such as ciliates (Alveolata) and bacterivorous amoebae (Amoebozoa), Rhizaria are poorly studied in terms of endosymbiotic relationships with heterotrophic bacteria. Therefore, our finding triggered the following questions. What is the phylogenetic affiliation of the bacteria residing in Viri...

show abstract

Biodiversity of “Non-model” Rickettsiales and Their Association with Aquatic Organisms

2016

View full text Add to dashboard Cite

Representatives of the order Rickettsiales are obligate intracellular bacteria, traditionally including well-studied pathogens of humans and other vertebrates, such as Rickettsia, Orientia, Anaplasma, and Ehrlichia. In the last two decades, studies based on molecular characterization techniques have reshaped our view on the biodiversity of Rickettsiales, and the eukaryotic hosts they can exploit. Several new genera have been described in “traditional” Rickettsiales families Rickettsiaceae and Anaplasmataceae. Moreover, a new family, “Candidatus Midichloriaceae,” displaying diversity at least comparable with the “traditional” ones, has been described. Recent data show that the majority of extant genera of Rickettsiales (16 out of 24) are hosted exclusively (or at least partly) by aquatic organisms, such as protists (e.g., ciliates, amoebas, flagellates), and animals (e.g., cnidarians, mollusks, tunicates, leeches), while only ten genera include some terrestrial host, such as arthropods. Given the highly interwoven phylogenetic relationships among Rickettsiales hosted by aquatic and terrestrial hosts, it is likely that the ancestral host of Rickettsiales was an aquatic protist organism, and the adaptation to terrestrial environments occurred independently in several distinct sublineages at least six times. Newly discovered lineages of “non-model” Rickettsiales present unforeseen features for the order such as the presence of flagella. Future investigations on “non-model” Rickettsiales are crucial to gain insight on the evolutionary history of the whole group, including the origin of molecular mechanisms involved in pathogenesis for humans and vertebrates

show abstract

A rickettsial endosymbiont inhabiting the cytoplasm of Volvox carteri (Volvocales, Chlorophyceae)

Cited by 13 publications

References 26 publications

Rickettsial endosymbiont in the “early‐diverging” streptophyte green alga Mesostigma viride

Rickettsial endosymbiont in the “early‐diverging” streptophyte green alga Mesostigma viride

“Candidatus Finniella” (Rickettsiales, Alphaproteobacteria), Novel Endosymbionts of Viridiraptorid Amoeboflagellates (Cercozoa, Rhizaria)

Biodiversity of “Non-model” Rickettsiales and Their Association with Aquatic Organisms

Contact Info

Product

Resources

About