Role of host ciliate Paramecium bursaria mitochondria and trichocysts for symbiotic Chlorella variabilis attachment beneath the host cell cortex.

Symbiotic Chlorella variabilis is encased in the perialgal vacuole (PV) membrane of ciliate Paramecium bursaria. The PV membrane is stably anchored below the host cell cortex by adhesion to host mitochondria. Host trichocysts, which are defensive organelles against predators, are present in the mitochondria and PV membrane vicinity.

A 63-kDa Periplasmic Protein of the Endonuclear Symbiotic Bacterium Secreted to the Outside of the Bacterium during the Early Infection Process Binds Weakly to the Macronuclear DNA of the Host .

The Gram-negative bacterium is a macronucleus-specific symbiont of the ciliate . It is known that an infection of this bacterium induces high level expressions of the host and genes, and the host cell acquires both heat-shock and high salt resistances. In addition, an infectious form of -specific 63-kDa periplasmic protein with a DNA-binding domain in its amino acid sequence is secreted into the host macronucleus after invasion into the macronucleus and remain within the nucleus.

Endosymbiotic Chlorella variabilis reduces mitochondrial number in the ciliate Paramecium bursaria.

Extant symbioses illustrate endosymbiosis is a driving force for evolution and diversification. In the ciliate Paramecium bursaria, the endosymbiotic alga Chlorella variabilis in perialgal vacuole localizes beneath the host cell cortex by adhesion between the perialgal vacuole membrane and host mitochondria. We investigated whether host mitochondria are also affected by algal endosymbiosis.

Mechanisms for establishing primary and secondary endosymbiosis in Paramecium.

Primary (eukaryote and procaryote) and secondary (eukaryote and eukaryote) endosymbioses are driving forces in eukaryotic cell evolution. These phenomena are still contributing to acquire new cell structures and functions. To understand mechanisms for establishment of each endosymbiosis, experiments that can induce endosymbiosis synchronously by mixing symbionts isolated from symbiont-bearing host cells and symbiont-free host cells are indispensable.

Genome plasticity in Paramecium bursaria revealed by population genomics.

Background: Ciliates are an ancient and diverse eukaryotic group found in various environments. A unique feature of ciliates is their nuclear dimorphism, by which two types of nuclei, the diploid germline micronucleus (MIC) and polyploidy somatic macronucleus (MAC), are present in the same cytoplasm and serve different functions. During each sexual cycle, ciliates develop a new macronucleus in which newly fused genomes are extensively rearranged to generate functional minichromosomes.

Peculiar Hosts Fail to Establish a Stable Intracellular Relationship With .

, an intracellular human pathogen, establishes intracellular relationships with several protist hosts, including . can escape the normal digestion process and establish intracellular relationships in . In this study, we identify new strains that significantly reduce the number of during infection.

Fiber-associated spirochetes are major agents of hemicellulose degradation in the hindgut of wood-feeding higher termites.

Symbiotic digestion of lignocellulose in wood-feeding higher termites (family Termitidae) is a two-step process that involves endogenous host cellulases secreted in the midgut and a dense bacterial community in the hindgut compartment. The genomes of the bacterial gut microbiota encode diverse cellulolytic and hemicellulolytic enzymes, but the contributions of host and bacterial symbionts to lignocellulose degradation remain ambiguous. Our previous studies of spp.

Identification of novel Legionella genes required for endosymbiosis in Paramecium based on comparative genome analysis with Holospora spp.

The relationship between Legionella and protist hosts has a huge impact when considering the infectious risk in humans because it facilitates the long-term replication and survival of Legionella in the environment. The ciliate Paramecium is considered to be a protist host for Legionella in natural environments, but the details of their endosymbiosis are largely unknown. In this study, we determined candidate Legionella pneumophila genes that are likely to be involved in the establishment of endosymbiosis in Paramecium caudatum by comparing the genomes of Legionella spp.

Crucial Role of TolC in the Inhibition of Cellular Trafficking in the Protistan Host .

is a facultative intracellular Gram-negative bacterium, which is a major causative agent of Legionnaires' disease. In the environment, this bacterium survives in free-living protists such as amoebae and . The association of and protists leads to the replication and spread of this bacterium.

High degree of specificity in the association between symbiotic betaproteobacteria and the host Euplotes (Ciliophora, Euplotia).

The Betaproteobacteria-Euplotes association is an obligatory symbiotic system involving a monophyletic group of ciliate species and two betaproteobacteria species which can be alternatively present. Recent data showed that this relationship has been established more than once and that several symbiont-substitution events took place, revealing a complex and intriguing evolutionary path. Due to the different evolutionary pathways followed by the different symbionts, each bacterial strain could have differentially evolved and/or lost functional traits.

Ciliate Paramecium is a natural reservoir of Legionella pneumophila.

Legionella pneumophila, the causative agent of Legionnaires' disease, replicates within alveolar macrophages and free-living amoebae. However, the lifestyle of L. pneumophila in the environment remains largely unknown.

Analysis of amino acid and codon usage in Paramecium bursaria.

The ciliate Paramecium bursaria harbors the green-alga Chlorella symbionts. We reassembled the P. bursaria transcriptome to minimize falsely fused transcripts, and investigated amino acid and codon usage using the transcriptome data.

Symbiotic Chlorella variabilis incubated under constant dark conditions for 24 hours loses the ability to avoid digestion by host lysosomal enzymes in digestive vacuoles of host ciliate Paramecium bursaria.

Endosymbiosis between symbiotic Chlorella and alga-free Paramecium bursaria cells can be induced by mixing them. To establish the endosymbiosis, algae must acquire temporary resistance to the host lysosomal enzymes in the digestive vacuoles (DVs). When symbiotic algae isolated from the alga-bearing paramecia are kept under a constant dark conditions for 24 h before mixing with the alga-free paramecia, almost all algae are digested in the host DVs.

Draft genome sequences of three Holospora species (Holospora obtusa, Holospora undulata, and Holospora elegans), endonuclear symbiotic bacteria of the ciliate Paramecium caudatum.

We present draft genome sequences of three Holospora species, hosted by the ciliate Paramecium caudatum; that is, the macronucleus-specific H. obtusa and the micronucleus-specific H. undulata and H.

Comparison of gene expression of Paramecium bursaria with and without Chlorella variabilis symbionts.

Background: The ciliate Paramecium bursaria harbors several hundred cells of the green-alga Chlorella sp. in their cytoplasm. Irrespective of the mutual relation between P.

Draft Genome Sequence of Holospora undulata Strain HU1, a Micronucleus-Specific Symbiont of the Ciliate Paramecium caudatum.

Holospora undulata is a micronucleus-specific symbiont of the ciliate Paramecium caudatum. We report here the draft genome sequence of H. undulata strain HU1.

Synchronous induction of detachment and reattachment of symbiotic Chlorella spp. from the cell cortex of the host Paramecium bursaria.

Paramecium bursaria harbor several hundred symbiotic Chlorella spp. Each alga is enclosed in a perialgal vacuole membrane, which can attach to the host cell cortex. How the perialgal vacuole attaches beneath the host cell cortex remains unknown.

Cell division and density of symbiotic Chlorella variabilis of the ciliate Paramecium bursaria is controlled by the host's nutritional conditions during early infection process.

The association of ciliate Paramecium bursaria with symbiotic Chlorella sp. is a mutualistic symbiosis. However, both the alga-free paramecia and symbiotic algae can still grow independently and can be reinfected experimentally by mixing them.

Characteristics of the digestive vacuole membrane of the alga-bearing ciliate Paramecium bursaria.

Cells of the ciliate Paramecium bursaria harbor symbiotic Chlorella spp. in their cytoplasm. To establish endosymbiosis with alga-free P.

Endosymbionts in paramecium.

Paramecium species are extremely valuable organisms to enable experiments for the reestablishment of endosymbiosis. This is investigated in two different systems, the first with Paramecium caudatum and the endonuclear symbiotic bacterium Holospora species. Although most endosymbiotic bacteria cannot grow outside the host cell as a result of their reduced genome size, Holospora species can maintain their infectivity for a limited time.

Symbiotic Chlorella vulgaris of the ciliate Paramecium bursaria plays an important role in maintaining perialgal vacuole membrane functions.

Treatment of symbiotic alga-bearing Paramecium bursaria cells with a protein synthesis inhibitor, cycloheximide, induces synchronous swelling of all perialgal vacuoles at about 24h after treatment under a constant light condition. Subsequently, the vacuoles detach from the host cell cortex. The algae in the vacuoles are digested by the host's lysosomal fusion to the vacuoles.

Secondary symbiosis between Paramecium and Chlorella cells.

Each symbiotic Chlorella species of Paramecium bursaria is enclosed in a perialgal vacuole (PV) membrane derived from the host digestive vacuole (DV) membrane. Algae-free paramecia and symbiotic algae are capable of growing independently and paramecia can be reinfected experimentally by mixing them. This phenomenon provides an excellent model for studying cell-to-cell interaction and the evolution of eukaryotic cells through secondary endosymbiosis between different protists.

Endosymbiosis of Chlorella species to the ciliate Paramecium bursaria alters the distribution of the host's trichocysts beneath the host cell cortex.

Each symbiotic Chlorella of the ciliate Paramecium bursaria is enclosed in a perialgal vacuole membrane derived from the host digestive vacuole membrane. Alga-free paramecia and symbiotic algae can grow independently. Mixing them experimentally can cause reinfection.

Comparison and critical evaluation of PCR-mediated methods to walk along the sequence of genomic DNA.

Although researchers can access information on the entire genomic DNA sequence of typical research organisms, convenient genome walking methods in the laboratory are still needed. For the analysis of microorganisms, these methods are especially useful because the available genetic information is often scarce or limited.Many genomic walking methods are based on the polymerase chain reaction (PCR), and useful methods have been developed.

High therapeutic effectiveness of postoperative irinotecan chemotherapy in a typical case of radiographically and pathologically diagnosed pleuropulmonary blastoma.

A 2-year 9-month-old girl with a large mass in the right chest underwent middle and inferior lobectomy, after which the mass was pathologically diagnosed as a pleuropulmonary blastoma (PPB). The clinical, radiographic, and pathologic findings were typical. Three courses of postoperative chemotherapy with 2 different regimens were ineffective in preventing multiple metastases of the lung.