A Molecular Approach to the Tangled Intrageneric Relationships Underlying Phylogeny in Euplotes (Ciliophora, Spirotrichea)

Petroni, Giulio; Dini, Fernando; Verni, Franco; Rosati, Giovanna

doi:10.1006/mpev.2001.1030

Cited by 116 publications

(115 citation statements)

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“…The two sequences are almost identical: there is only one difference at a single nucleotide position (nucleotide 1675, which is an "A" in HS11/7 and a "T" in BOD18). The 18S rRNA gene sequence of strain HS11/7 is identical to the sequence of Euplotes harpa FSP1.4 that had been collected some years before in the same pond (EMBL accession number AJ811015F [50]) and present one-nucleotide difference with respect to the sequences of E. harpa FC1 (EMBL accession number AJ811016 [50]) and BOD2 (EMBL accession number AJ305252 [35]). In turn, this last sequence is identical to that of BOD18; indeed, both strains were collected at the same time in the same locality, and they differ by two nucleotides respect to the 18S rRNA sequence of strain FC1.…”

Section: Resultsmentioning

confidence: 76%

“…PCRs were carried out with a Primus 96 Plus thermocycler (MWG Biotech, Ebersberg, Germany). The 18S rRNA gene of host ciliates was amplified using the forward primer 18S F9 (5Ј-CTG GTT GAT CCT GCC AG-3Ј [30]) together with the reverse primer 18S R1513 Hypo (5Ј-TGA TCC TTC YGC AGG TTC-3Ј [35]). The reaction was performed with annealing taking place at 57°C for 35 cycles.…”

Section: Methodsmentioning

confidence: 99%

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“CandidatusAnadelfobacter veles” and “CandidatusCyrtobacter comes,” Two NewRickettsialesSpecies Hosted by the Protist CiliateEuplotes harpa(Ciliophora, Spirotrichea)

Vannini

Ferrantini

Schleifer

et al. 2010

Appl Environ Microbiol

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The order Rickettsiales (Alphaproteobacteria) is a well-known group containing obligate endocellular prokaryotes. The order encompasses three families (Rickettsiaceae, Anaplasmataceae, and Holosporaceae) and a fourth, family-level cluster, which includes only one candidate species, "Candidatus Midichloria mitochondrii," as well as several unnamed bacterial symbionts. The broad host range exhibited by the members of the "Candidatus Midichloria" clade suggests their eventual relevance for a better understanding of the evolution of symbiosis and host specificity of Rickettsiales. In this paper, two new bacteria belonging to the "Candidatus Midichloria" clade, hosted by two different strains of the ciliate protist Euplotes harpa, are described on the basis of ultrastructural observations, comparative 16S rRNA gene sequence analysis, and an estimation of the percentage of infection. Ultrastructure of these bacteria shows some unusual features: one has an electrondense cytoplasm, and the other one lacks a symbiosomal membrane. The latter was up to now considered an exclusive feature of bacteria belonging to the family Rickettsiaceae. 16S rRNA gene phylogenetic analysis unambiguously places the new bacteria in the "Candidatus Midichloria" clade, although their phylogenetic relationships with other members of the clade are not clearly resolved. This is the first report of a ciliate-borne bacterium belonging to the "Candidatus Midichloria" clade. On the basis of the data obtained, the two bacteria are proposed as two new candidate genera and species, "Candidatus Anadelfobacter veles" and "Candidatus Cyrtobacter comes."

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Section: Resultsmentioning

confidence: 76%

Section: Methodsmentioning

confidence: 99%

“CandidatusAnadelfobacter veles” and “CandidatusCyrtobacter comes,” Two NewRickettsialesSpecies Hosted by the Protist CiliateEuplotes harpa(Ciliophora, Spirotrichea)

Vannini

Ferrantini

Schleifer

et al. 2010

Appl Environ Microbiol

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“…The DNA was isolated following the standard protocol of Sambrook et al (1989), modified and optimized for the genomic DNA isolation from protists, as reported by Fokin et al (2008). The SSU-rRNA gene, universally considered a good species-specific marker, was amplified by PCR using the universal eukaryotic forward primer 18S F9 5'-CTGGTTGATCCTGCCAG-3' (Medlin et al, 1988) and the 18S R1513 Hypo reverse primer 5'-TGATCCTTCYGCAGGTTC-3' (Petroni et al, 2002). The PCR product was purified and directly sequenced in both directions.…”

Section: Culture Conditions and Molecular Characterizationmentioning

confidence: 99%

Changes in the non-protein thiol pool and production of dissolved gaseous mercury in the marine diatom Thalassiosira weissflogii under mercury exposure

Morelli

Ferrara

Bellini

et al. 2009

Science of The Total Environment

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Two detoxification mechanisms working in the marine diatom Thalassiosira weissfloggii to cope with mercury toxicity were investigated. Initially, the effect of mercury on the intracellular pool of non-protein thiols was studied in exponentially growing cultures exposed to sub-toxic HgCl 2 concentrations. T. weissfloggii cells responded by synthesizing metalbinding peptides, named phytochelatins (PCs), besides increasing the intracellular pool of glutathione and γ-glutamylcysteine (γ-EC). Intracellular Hg and PC concentrations increased with the Hg concentration in the culture medium, exhibiting a distinct dose-response relationship. However, considerations of the PCs-SH:Hg molar ratio suggest that also glutathione could be involved in the intracellular mercury sequestration. The time course of the non-protein thiol pool and Hg intracellular concentration shows that PCs, glutathione and γ-EC represent a rapid cellular response to mercury, although their role in Hg detoxification seems to lose importance at longer incubation times. The occurrence of a process of reduction of Hg(II) to Hg° and subsequent production of dissolved gaseous mercury (DGM) was also investigated at lower Hg concentrations, at which the PC synthesis doesn't seem to be involved. The significant (P<0.01) correlation between the cellular density in solution and the production of DGM suggests that this diatom is capable of directly producing DGM, both in light and dark conditions. This finding has been confirmed by the absence of DGM production in the culture media containing formaldehyde-killed cells. Finally, the relationship between these two different pathways of Hg detoxification is discussed.

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“…In other cases, neither the symbiont nor the host can live without the other. A group of species of Euplotes, phylogenetically correlated despite differences in morphological and ecological characteristics (Petroni et al 2002), harbour similar bacteria. The best-known species is Polynucleobacter necessarius, formerly omikron (Heckmann 1975), an endosymbiont of E. aediculatus (Heckmann et al 1983).…”

Section: Introductionmentioning

confidence: 99%

Euplotes magnicirratus (Ciliophora, Hypotrichia) depends on its bacterial endosymbiont 'Candidatus Devosia euplotis' for food digestion

Vannini¹,

Schena²,

Verni³

et al. 2004

Aquat. Microb. Ecol.

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A symbiotic relationship between the marine ciliate Euplotes magnicirratus and an alpha-proteobacterium has recently been described. The bacterial symbiont, identified by molecular analysis as a new species of the genus Devosia, is referred to with the provisional name 'Candidatus Devosia euplotis'. This association is constant (it was found in different ciliate strains sampled in different geographical regions), and durable (it persisted in laboratory conditions for years). The physiological significance of this association was investigated through antibiotically produced aposymbiotic E. magnicirratus and attempts to grow the endosymbionts outside their host. Aposymbiotic protozoa completely lost the ability to digest the green alga Dunaliella tertiolecta, their usual food in laboratory conditions, and died. An investigation into the different steps of the digestive process showed that acidification of the digestive vacuoles occurred normally in both symbiotic and aposymbiotic ciliates, but that subsequent activation of acid phosphatase did not occur in aposymbiotic cells. Therefore, the ciliate depends on the symbiont for digestion of its green algal food and, as a consequence, for its survival. Attempts to grow bacterial endosymbionts on diluted culture media and on ciliate homogenate were unsuccessful. The results indicate that this represents a new type of symbiosis between prokaryotes and ciliates, which is mutualistic, and most likely obligatory for both partners.KEY WORDS: Alpha-proteobacteria · Ciliates · Devosia · Digestive process · Euplotes · Lysis · SymbiosisResale or republication not permitted without written consent of the publisher

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A Molecular Approach to the Tangled Intrageneric Relationships Underlying Phylogeny in Euplotes (Ciliophora, Spirotrichea)

Cited by 116 publications

References 57 publications

“CandidatusAnadelfobacter veles” and “CandidatusCyrtobacter comes,” Two NewRickettsialesSpecies Hosted by the Protist CiliateEuplotes harpa(Ciliophora, Spirotrichea)

“CandidatusAnadelfobacter veles” and “CandidatusCyrtobacter comes,” Two NewRickettsialesSpecies Hosted by the Protist CiliateEuplotes harpa(Ciliophora, Spirotrichea)

Changes in the non-protein thiol pool and production of dissolved gaseous mercury in the marine diatom Thalassiosira weissflogii under mercury exposure

Euplotes magnicirratus (Ciliophora, Hypotrichia) depends on its bacterial endosymbiont 'Candidatus Devosia euplotis' for food digestion

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