| r-body-producing bacteria. | until 10 years ago, r bodies were known only as diagnostic features by which endosymbionts of paramecia were identified as kappa particles. they were thought to be limited to the cytoplasm of two species in the paramecium aurelia species complex. now, r bodies have been found in free-living bacteria and other paramecium species. the organisms now known to form r bodies include the cytoplasmic kappa endosymbionts of p. biaurelia and p. tetraurelia, the macronuclear kappa endosymbionts of p. cauda ... | 1989 | 2651865 |
| transposonlike elements in caedibacter taeniospiralis. | we report that the 1.5- and 7.5-kilobase-pair (kbp) transposonlike sequences present in the r-body-coding plasmids of caedibacter taeniospiralis share homology. the r-body-coding plasmids of two new strains of c. taeniospiralis, derived from strains 169 and a30, carry the 7.5- and 1.5-kbp elements, respectively, inserted at new positions. sequences homologous to the 7.5-kbp sequence from c. taeniospiralis 47 were detected in the chromosomes of three other strains of c. taeniospiralis. | 1986 | 3007438 |
| a mutation in the r body-coding sequence destroys expression of the killer trait in p. tetraurelia. | this report describes a mutant strain of caedibacter taeniospiralis 169 that does not produce refractile (r) bodies or kill sensitive paramecia, but still renders its host resistant to killing by wild-type strains of caedibacter taeniospiralis. the mutation is due to insertion of a 7.5-kilobase, transposon-like element into the r body-coding region of the plasmid pkap169. the results provide strong evidence that r body synthesis is required for expression of the killer trait. | 1986 | 3008334 |
| organization and expression of genetic determinants for synthesis and assembly of type 51 r bodies. | type 51 r bodies are produced by all bacterial endosymbionts (caedibacter taeniospiralis) of paramecium tetraurelia that confer the hump-killer trait upon their hosts. type 51 r-body synthesis by c. taeniospiralis is required for expression of the hump-killer trait. the genetic determinants for type 51 r-body synthesis by c. taeniospiralis 47 have been cloned and expressed in escherichia coli. in this communication we describe three species of polypeptides required for r-body synthesis and the o ... | 1986 | 3759909 |
| physical map of a plasmid from caedibacter taeniospiralis 51. | caedibacter taeniospiralis 51 carries at least two plasmids, pkap51 and pkap52. the smaller plasmid, pkap51, contains 43 kilobase pairs. the larger plasmid, pkap52, contains more than 110 kilobase pairs. relative positions of recognition sequences for seven different restriction endonucleases were determined, and a physical map of pkap51, consisting of a total of 28 restriction sites, was constructed. | 1982 | 6290459 |
| plasmids from bacterial endosymbionts of hump-killer paramecia. | six isolates of caedibacter taeniospiralis, collected from four continents, were screened for plasmid dna. plasmid dna species containing between 41.5 and 49.5 kilobase pairs (kb) were observed in all strains. physical maps of plasmids were constructed by determining relative positions of the restriction endonuclease (bamhi, sali, xhoi, saci, psti, avai, and ecori) recognition sequences in each plasmid. the physical map of the smallest plasmid (41.5 kb), pkap30, is reflected in each of the plasm ... | 1983 | 6306706 |
| cloning and expression of dna sequences associated with the killer trait of paramecium tetraurelia stock 47. | we have presented direct evidence that at least one of the traits associated with killing of paramecia by kappa particles is determined by an extrachromosomal genetic element. plasmid dna was isolated from caedibacter taeniospiralis 47 (commonly known as 47 kappa), which is an obligate cytoplasmic endosymbiont of paramecium tetraurelia. fragments of pkap47 dna generated by pst i digestion were inserted into pbr328 and then introduced into escherichia coli 294 by transformation. clones carrying r ... | 1983 | 6571998 |
| characterization of genetic determinants for r body synthesis and assembly in caedibacter taeniospiralis 47 and 116. | caedibacter taeniospiralis, an obligate bacterial endosymbiont of paramecium tetraurelia, confers a killing trait upon its host paramecium. type 51 r bodies (refractile inclusion bodies) are synthesized by these endosymbionts and are required for expression of the killing trait. the nucleotide sequence of the genetic determinants for type 51 r body synthesis and assembly was determined for c. taeniospiralis 47 and 116. three independently transcribed genes (reba, rebb, and rebc) were characteriz ... | 1994 | 8206833 |
| the genus caedibacter comprises endosymbionts of paramecium spp. related to the rickettsiales (alphaproteobacteria) and to francisella tularensis (gammaproteobacteria). | obligate bacterial endosymbionts of paramecia able to form refractile inclusion bodies (r bodies), thereby conferring a killer trait upon their ciliate hosts, have traditionally been grouped into the genus caedibacter: of the six species described to date, only the paramecium caudatum symbiont caedibacter caryophilus has been phylogenetically characterized by its 16s rrna gene sequence, and it was found to be a member of the alphaproteobacteria related to the rickettsiales: in this study, the ca ... | 2002 | 12450827 |
| sequence, transcription activity, and evolutionary origin of the r-body coding plasmid pkap298 from the intracellular parasitic bacterium caedibacter taeniospiralis. | we isolated the intracellular parasitic bacterium caedibacter taeniospiralis from cultures of the freshwater ciliate paramecium tetraurelia strain 298. plasmid pkap298 as well as the total rna were isolated from the bacteria. pkap298 was totally sequenced (49.1 kb; ncbi accession number ay422720). from southern blots of pkap-fragments and digoxigenin-labeled cdna of the caedibacter-rna, we generated transcription maps of pkap298. the observed transcription activity indicated functions of the pla ... | 2005 | 15785846 |
| molecular characterization of the obligate endosymbiont "caedibacter macronucleorum"fokin and görtz, 1993 and of its host paramecium duboscqui strain ku4-8. | bacterial endosymbionts of protozoa were often described as new species by protozoologists mainly on the basis of few morphological characters and partly by host specificity. many of these species have never been validated by prokaryotic microbiologists whose taxonomic rules are quite different from those of protozoologists, who use the zoological code of nomenclature. "caedibacter macronucleorum"fokin and görtz 1993, an endosymbiont of paramecium duboscqui, belongs to this category. here we pro ... | 2006 | 17123414 |
| fangia hongkongensis gen. nov., sp. nov., a novel gammaproteobacterium of the order thiotrichales isolated from coastal seawater of hong kong. | a gram-negative, coccobacillus-shaped, aerobic bacterium, designated strain ust040201-002t, was isolated in february 2004 from seawater at the outlet of a sandfilter in port shelter, hong kong sar, china. this strain possessed ubiquinone-8; its 16s rrna gene sequence shared only 91% similarity with the sequence from caedibacter taeniospiralis and 89-90% similarity with sequences from francisella tularensis, francisella novicida, francisella philomiragia and wolbachia persica. 16s rrna gene seque ... | 2007 | 17978237 |
| phrr-like gene prar of azorhizobium caulinodans ors571 is essential for symbiosis with sesbania rostrata and is involved in expression of reb genes. | this study focuses on the function of the gene prar that encodes a putative transcription factor in azorhizobium caulinodans ors571, a microsymbiont of sesbania rostrata. the prar gene is a homolog of the phrr gene of sinorhizobium medicae wsm419, and the prar and phrr homologs are distributed throughout the class alphaproteobacteria. the growth and nitrogen fixation activity of an a. caulinodans prar deletion mutant in the free-living state were not significantly different from those of the wil ... | 2010 | 20382809 |
| isolation and characterisation of the trichocysts of the dinophyte prorocentrum micans. | trichocyst-enriched fractions were isolated from the marine dinophyte prorocentrum micans. transmission electron microscopy revealed that most of the trichocysts were discharged and had elongated to long filaments. some trichocysts were still condensed. fragments of discharged trichocysts measured up to 20 μm in length and 260 nm in width, those still condensed measured up to 1 μm in width and 16 μm in length. a distinct banding pattern with a transversal periodicity of approximately 16-18 nm an ... | 2015 | 25030517 |
| vertically transmitted symbiont reduces host fitness along temperature gradient. | parasites with exclusive vertical transmission from host parent to offspring are an evolutionary puzzle. with parasite fitness entirely linked to host reproduction, any fitness cost for infected hosts risks their selective elimination. environmental conditions likely influence parasite impact and thereby the success of purely vertical transmission strategies. we tested for temperature-dependent virulence of caedibacter taeniospiralis, a vertically transmitted bacterial symbiont of the protozoan ... | 2014 | 24779056 |
| isolation and characterization of the ejectisomes of the prasinophyte pyramimonas grossii. | for the first time, ejectisome-enriched fractions were isolated from the marine prasinophyte pyramimonas grossii. transmission electron microscopy revealed that most of the ejectisomes were discharged and formed long, spirally twisted filaments. some ejectisomes were still fully or partly furled. discharged ejectisomes measured up to 26 μm in length and 200 nm in width; those still furled measured up to 900 nm in width and 1,000 nm in length. particle periodicities of approximately 4.2 and 5.8 n ... | 2013 | 23779212 |
| ejectisins: tough and tiny polypeptides are a major component of cryptophycean ejectisomes. | fragments of discharged ejectisomes were isolated from two cryptomonas and a chroomonas species by detergent treatment followed by percoll density gradient centrifugation. the fragments withstand high concentrated detergent solutions, reducing agents and freeze-thawing. disintegration was achieved in 6 m guanidine hydrochloride. reassembly into long, filamentous, ejectisome-like structures occurred after dialysis. sodium dodecyl sulfate polyacrylamide gel electrophoresis revealed that the polype ... | 2013 | 22868567 |
| trichocyst ribbons of a cryptomonads are constituted of homologs of r-body proteins produced by the intracellular parasitic bacterium of paramecium. | trichocysts are ejectile organelles found in cryptomonads, dinoflagellates, and peniculine ciliates. the fine structure of trichocysts differs considerably among lineages, and their evolutionary relationships are unclear. the biochemical makeup of the trichocyst constituents has been studied in the ciliate paramecium, but there have been no investigations of cryptomonads and dinoflagellates. furthermore, morphological similarity between the contents of cryptomonad trichocysts and the r-bodies of ... | 2012 | 22447322 |
| tracing the role of r-bodies in the killer trait: absence of toxicity of r-body producing recombinant e. coli on paramecia. | r-bodies are coiled proteinaceous ribbons produced by paramecium endosymbionts belonging to the genus caedibacter. these intracellular bacteria confer upon their hosts a phenomenon called the killer trait. it is the ability to kill symbiont-free competitors called sensitives. the r-body is the crucial element of this process, but despite many efforts, the actual role of r-bodies in killing sensitive paramecia is still not satisfactory clarified. the open question is whether the r-body acts as tr ... | 2012 | 22356923 |