Holospora-like bacteria "Candidatus Gortzia yakutica" and Preeria caryophila: Ultrastructure, promiscuity, and biogeography of the symbionts.

Two already known representatives of Holospora-like bacteria, "Candidatus Gortzia yakutica" from Paramecium putrinum and Preeria caryophila, originally retrieved from the Paramecium aurelia complex, were found in new hosts: Paramecium nephridiatum and Paramecium polycaryum, respectively. In the present study, these bacteria were investigated using morphological and molecular methods. For "Ca.

Bacterial symbiosis in ciliates (Alveolata, Ciliophora): Roads traveled and those still to be taken.

The diversity of prokaryotic symbionts in Ciliophora and other protists is fascinatingly rich; they may even include some potentially pathogenic bacteria. In this review, we summarize currently available data on biodiversity and some morphological and biological peculiarities of prokaryotic symbionts mainly within the genera Paramecium and Euplotes. Another direction of ciliate symbiology, neglected for a long time and now re-discovered, is the study of epibionts of ciliates.

'Candidatus Gromoviella agglomerans', a novel intracellular Holosporaceae parasite of the ciliate Paramecium showing marked genome reduction.

Holosporales are an alphaproteobacterial lineage encompassing bacteria obligatorily associated with multiple diverse eukaryotes. For most representatives, little is known on the interactions with their hosts. In this study, we characterized a novel Holosporales symbiont of the ciliate Paramecium polycaryum.

Prof. H.-D. Görtz and his contribution to our knowledge of protozoan symbiosis.

Since the beginning of the 1980s, the Paramecium-Holospora system has become an important model and a subject of international scientific cooperation in symbiosis studies, established by Prof. H.-D.

Trichorickettsia mobilis", a bacterium, can be transiently transferred from the unicellular eukaryote to the planarian .

Most of the microorganisms responsible for vector-borne diseases (VBD) have hematophagous arthropods as vector/reservoir. Recently, many new species of microorganisms phylogenetically related to agents of VBD were found in a variety of aquatic eukaryotic hosts; in particular, numerous new bacterial species related to the genus (, ) were discovered in protist ciliates and other unicellular eukaryotes. Although their pathogenicity for humans and terrestrial animals is not known, several indirect indications exist that these bacteria might act as etiological agents of possible VBD of aquatic organisms, with protists as vectors.

Parablepharisma (Ciliophora) is not a Heterotrich: A Phylogenetic and Morphological Study with the Proposal of New Taxa.

The genus Parablepharisma Jankowski, 2007 at present includes five species, most of which have not been studied in detail, therefore phylogenetic affinities remained uninvestigated up to now. Parablepharisma is traditionally placed within Heterotrichea based on insufficient existing morphological data, and there are no available Parablepharisma gene sequences in molecular databases to support this placement. This work presents an 18S rDNA-based phylogeny of P.

"Candidatus Hafkinia simulans" gen. nov., sp. nov., a Novel Holospora-Like Bacterium from the Macronucleus of the Rare Brackish Water Ciliate Frontonia salmastra (Oligohymenophorea, Ciliophora): Multidisciplinary Characterization of the New Endosymbiont and Its Host.

We characterized a novel Holospora-like bacterium (HLB) (Alphaproteobacteria, Holosporales) living in the macronucleus of the brackish water ciliate Frontonia salmastra. This bacterium was morphologically and ultrastructurally investigated, and its life cycle and infection capabilities were described. We also obtained its 16S rRNA gene sequence and performed in situ hybridization experiments with a specifically-designed probe.

Detecting Associations Between Ciliated Protists and Prokaryotes with Culture-Independent Single-Cell Microbiomics: a Proof-of-Concept Study.

Symbioses between prokaryotes and microbial eukaryotes, particularly ciliated protists, have been studied for a long time. Nevertheless, researchers have focused only on a few host genera and species, mainly due to difficulties in cultivating the hosts, and usually have considered a single symbiont at a time. Here, we present a pilot study using a single-cell microbiomic approach to circumvent these issues.

The Hidden World of Rickettsiales Symbionts: "Candidatus Spectririckettsia obscura," a Novel Bacterium Found in Brazilian and Indian Paramecium caudatum.

Symbioses between bacteria and eukaryotes are widespread and may have significant impact on the evolutionary history of symbiotic partners. The order Rickettsiales is a lineage of intracellular Alphaproteobacteria characterized by an obligate association with a wide range of eukaryotic hosts, including several unicellular organisms, such as ciliates and amoebas. In this work, we characterized the Rickettsiales symbionts associated with two different genotypes of the freshwater ciliate Paramecium caudatum originated from freshwater environments in distant geographical areas.

Symbiont replacement between bacteria of different classes reveals additional layers of complexity in the evolution of symbiosis in the ciliate Euplotes.

Symbiosis is a diverse and complex phenomenon requiring diverse model systems. The obligate relationship between a monophyletic group of Euplotes species ("clade B") and the betaproteobacteria Polynucleobacter and "Candidatus Protistobacter" is among the best-studied in ciliates, and provides a framework to investigate symbiont replacements. Several other Euplotes-bacteria relationships exist but are less understood, such as the co-dependent symbiosis between Euplotes magnicirratus (which belongs to "clade A") and the alphaproteobacterium "Candidatus Devosia euplotis".

Strengths and Biases of High-Throughput Sequencing Data in the Characterization of Freshwater Ciliate Microbiomes.

Molecular surveys of eukaryotic microbial communities employing high-throughput sequencing (HTS) techniques are rapidly supplanting traditional morphological approaches due to their larger data output and reduced bench work time. Here, we directly compare morphological and Illumina data obtained from the same samples, in an effort to characterize ciliate faunas from sediments in freshwater environments. We show how in silico processing affects the final outcome of our HTS analysis, providing evidence that quality filtering protocols strongly impact the number of predicted taxa, but not downstream conclusions such as biogeography patterns.

Rare Freshwater Ciliate Paramecium chlorelligerum Kahl, 1935 and Its Macronuclear Symbiotic Bacterium "Candidatus Holospora parva".

Ciliated protists often form symbioses with many diverse microorganisms. In particular, symbiotic associations between ciliates and green algae, as well as between ciliates and intracellular bacteria, are rather wide-spread in nature. In this study, we describe the complex symbiotic system between a very rare ciliate, Paramecium chlorelligerum, unicellular algae inhabiting its cytoplasm, and novel bacteria colonizing the host macronucleus.

" Gortzia shahrazadis", a Novel Endosymbiont of and a Revision of the Biogeographical Distribution of -Like Bacteria.

spp. and " Gortzia infectiva", known as -like bacteria (HLB), are commonly found as nuclear endosymbionts of ciliates, especially the genus. HLB are related by phylogenetic relationships, morphological features, and life-cycles, which involve two alternating morphotypes: reproductive and infectious forms (RF, IF).

Ciliate communities and hidden biodiversity in freshwater biotopes of the Pistoia province (Tuscany, Italy).

Ciliates are essential components of aquatic environments, playing a pivotal role in microbial loops. Thus, the composition and dynamics of ciliate communities have been subjected to intense studying. Morphological methods have been traditionally employed, until the development of next-generation sequencing recently allowed to explore the topic with exclusively molecular techniques.

Response of the bacterial symbiont Holospora caryophila to different growth conditions of its host.

Previous studies on bacterial symbionts of ciliates have shown that some symbionts can be maintained relatively well under standard laboratory conditions whereas others are frequently lost, especially when the host is cultivated at a high division rate. In this study, the variation in infection level by the endosymbiont Holospora caryophila within its host population Paramecium octaurelia was investigated in response to three alimentary treatments and a subsequent starvation phase. The response of the ciliates was determined as a nearly exponential growth rate with different slopes in each treatment, proportional to the amount of food received.

Focusing on genera to improve species identification: revised systematics of the ciliate Spirostomum.

Although many papers dealing with the description of new ciliate taxa are published each year, species taxonomy and identification in most groups of the phylum Ciliophora remain confused. This is largely due to a scarcity of surveys on the systematics of immediately higher levels (genera and families) providing data for old and new species together. Spirostomum is a common and distinctive inhabitant of fresh- and brackish water environments, including artificial and eutrophic ones, and is a good model for applied ecology and symbiosis research.

Free-living ciliates as potential reservoirs for eukaryotic parasites: occurrence of a trypanosomatid in the macronucleus of Euplotes encysticus.

Background: Flagellates of the family Trypanosomatidae are obligate endoparasites, which can be found in various hosts. Several genera infect insects and occur as monoxenous parasites especially in representatives of Diptera and Hemiptera. These trypanosomatid flagellates probably share the worldwide distribution of their hosts, which are often infested by large numbers of endoparasites.

Flagellar movement in two bacteria of the family rickettsiaceae: a re-evaluation of motility in an evolutionary perspective.

Bacteria of the family Rickettsiaceae have always been largely studied not only for their importance in the medical field, but also as model systems in evolutionary biology. In fact, they share a recent common ancestor with mitochondria. The most studied species, belonging to genera Rickettsia and Orientia, are hosted by terrestrial arthropods and include many human pathogens.

Morphology, ultrastructure, and molecular phylogeny of the ciliate Sonderia vorax with insights into the systematics of order Plagiopylida.

Background: Ciliates of the family Sonderiidae are common members of the eukaryotic communities in various anoxic environments. They host both ecto- and endosymbiotic prokaryotes (the latter associated with hydrogenosomes) and possess peculiar morpho-ultrastructural features, whose functions and homologies are not known. Their phylogenetic relationships with other ciliates are not completely resolved and the available literature, especially concerning electron microscopy and molecular studies, is quite scarce.

Global lack of flyway structure in a cosmopolitan bird revealed by a genome wide survey of single nucleotide polymorphisms.

Knowledge about population structure and connectivity of waterfowl species, especially mallards (Anas platyrhynchos), is a priority because of recent outbreaks of avian influenza. Ringing studies that trace large-scale movement patterns have to date been unable to detect clearly delineated mallard populations. We employed 363 single nucleotide polymorphism markers in combination with population genetics and phylogeographical approaches to conduct a population genomic test of panmixia in 801 mallards from 45 locations worldwide.

Life of Alexander Onufrievich Kowalevsky (1840-1901).

A short description of the life of the famous Russian embryologist and zoologist Alexander O. Kowalevsky is presented, including some rare photos of the scientist.

Survey of Paramecium duboscqui using three markers and assessment of the molecular variability in the genus Paramecium.

The genus Paramecium (phylum Ciliophora) is one of the best-known among protozoa. Nevertheless, the knowledge on the diversity and distribution of species within this genus was remarkably scarce until recent times. In the last years a constantly growing amount of data has formed, especially on the distribution of species and the characterization of molecular markers.

Revised systematics of Holospora-like bacteria and characterization of "Candidatus Gortzia infectiva", a novel macronuclear symbiont of Paramecium jenningsi.

The genus Holospora (Rickettsiales) includes highly infectious nuclear symbionts of the ciliate Paramecium with unique morphology and life cycle. To date, nine species have been described, but a molecular characterization is lacking for most of them. In this study, we have characterized a novel Holospora-like bacterium (HLB) living in the macronuclei of a Paramecium jenningsi population.

Characterization of "Candidatus Nebulobacter yamunensis" from the cytoplasm of Euplotes aediculatus (Ciliophora, Spirotrichea) and emended description of the family Francisellaceae.

Our knowledge of ciliate endosymbionts occurrence and diversity greatly expanded in the last decades, due to the development of characterization methods for uncultivable bacteria. Symbionts related to human pathogens such as rickettsiae and francisellae have been detected inside the cytoplasm of different ciliate species. In the present work, we have characterized a novel Francisella-related bacterium inside the rich prokaryotic community harbored by a population of Euplotes aediculatus (Ciliophora, Spirotrichea).