Publications

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. elegans. we investigate functions of orthologous core genes conserved across the three holospora species, which may be essential for the infection and survival in the host nucleus.	2014	25115770
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. this bacterium was morphologically and ultrastructurally investigated in detail, and its life cycle and infec ...	2013	22940732
route of infection of the bacteria holospora elegans and holospora obtusa into the nuclei of paramecium caudatum.	the route of infection of two endonucleobiotic bacteria in paramecium caudatum was investigated with the electron microscope. the bacterium holospora elegans specifically infects the micronucleus, whereas holospora obtusa infects the macronucleus. the infectious forms of both bacteria are ingested by the prospective host cell into a phagosome. the bacteria leave the phagosome without destroying its membrane. during their transport to the nuclei the bacteria remain surrounded by host membranes fo ...	2011	23195560
[In Process Citation].		2011	22168016
actin-based mechanism of holospora obtusa trafficking in paramecium caudatum.	holospora obtusa, an alpha-proteobacterium, is an obligate endonuclear pathogen of the ciliate paramecium caudatum. it is engulfed by the host cell in the course of phagocytosis but soon escapes from the phagosome and is transported across the host cell cytoplasm to the paramecium macronucleus. electron microscopy reveals a comet-like tail resembling that of listeria trailing after h. obtusa in the host cytoplasm. in this study we investigated the role of the host cell actin and arp3 in the proc ...	2009	19231281
"candidatus paraholospora nucleivisitans", an intracellular bacterium in paramecium sexaurelia shuttles between the cytoplasm and the nucleus of its host.	an intracellular bacterium was discovered in two isolates of paramecium sexaurelia from an aquarium with tropical fish in münster (germany) and from a pond in the wilhelma zoological-botanical garden, stuttgart (germany). the bacteria were regularly observed in the cytoplasm of the host, but on some occasions they were found in the macronucleus of the host cell. in these cases, only a few, if any, bacteria were observed remaining in the cytoplasm. the bacterium was not infectious to p. sexaureli ...	2009	19679418
micronucleus-specific bacterium holospora elegans irreversibly enhances stress gene expression of the host paramecium caudatum.	the bacterium holospora is an endonuclear symbiont of the ciliate paramecium. previously, we reported that paramecia bearing the macronuclear-specific symbiont holospora obtusa survived better than symbiont-free paramecia, even under high temperatures unsuitable for growth. the paramecia with symbionts expressed high levels of hsp70 mrnas even at 25 degrees c, a usual growth temperature. we report herein that paramecia bearing the micronuclear-specific symbiont holospora elegans also acquire the ...	2008	19120797
fate of the 63-kda periplasmic protein of the infectious form of the endonuclear symbiotic bacterium holospora obtusa during the infection process.	holospora obtusa is a macronucleus-specific endosymbiotic bacterium of the ciliate paramecium caudatum. we report the secretion of a 63-kda periplasmic protein of an infectious form of the bacterium into the macronucleus of its host. indirect immunofluorescence microscopy with five monoclonal antibodies against the 63-kda protein demonstrated that, soon after the bacterial invasion into the host macronucleus, the protein was detected in the infected macronucleus and that levels of the protein in ...	2008	18179589
nocodazole inhibits macronuclear infection with holospora obtusa in paramecium caudatum.	holospora obtusa is a gram-negative bacterium inhabiting the macronucleus of the ciliate paramecium caudatum. experimental infection with h. obtusa was carried out under nocodazole treatment. nocodazole has been shown to cause disassembly of the cytoplasmic microtubules radiating from the cytopharynx and postoral fibers in p. caudatum. treatment with this drug did not prevent the ingestion of both prey bacteria and h. obtusa, but it reduced the phagosome number and affected cyclosis. in situ hyb ...	2005	16333573
translocation of an 89-kda periplasmic protein is associated with holospora infection.	the symbiotic bacterium holospora obtusa infects the macronucleus of the ciliate paramecium caudatum. after ingestion by its host, an infectious form of holospora with an electron-translucent tip passes through the host digestive vacuole and penetrates the macronuclear envelope with this tip. to investigate the underlying molecular mechanism of this process, we raised a monoclonal antibody against the tip-specific 89-kda protein, sequenced this partially, and identified the corresponding complet ...	2005	16236256
paramecium caudatum acquires heat-shock resistance in ciliary movement by infection with the endonuclear symbiotic bacterium holospora obtusa.	holospora obtusa is a macronucleus-specific bacterium of the ciliate paramecium caudatum. three types of p. caudatum cells (h. obtusa-free cells, cells bearing the reproductive form of h. obtusa and cells bearing the predominantly infectious form of h. obtusa) cultured at 25 degrees c were transferred to 4, 10, 25, 35 and 40 degrees c and their swimming velocities were measured by taking photomicrographs with two-second exposures. the h. obtusa-free cells almost ceased swimming at both 4 and 40 ...	2005	15668007
co-infection of the macronucleus of paramecium caudatum by free-living bacteria together with the infectious holospora obtusa.	infection experiments were performed incubating paramecium caudatum with non-infectious free-living bacteria or weakly infectious intracellular bacteria together with the infectious holospora obtusa. two of four non-infectious free-living bacteria (enterobacter aerogenes and klebsiella pneumoniae) were found to get into the nuclei when added to paramecium together with h. obtusa. the endonuclear bacterium nonospora macronucleata that is weakly infectious by itself increases its infectivity when ...	2004	15352323
differences in gene expression of the ciliate paramecium caudatum caused by endonuclear symbiosis with holospora obtusa, revealed using differential display reverse transcribed pcr.	we identified six genes of paramecium caudatum, which differentially expressed in holospora obtusa-bearing and h. obtusa-free cells using differential display reverse transcribed pcr (ddrt-pcr). northern blot analyses revealed that two of the genes, ca10-3 and ca20-2, were expressed extensively in the h. obtusa-free cell, while the other four, as16-1, cs14, cs21 and ca17-1, were expressed more in the h. obtusa-bearing cell. putative amino acid sequences of ca10-3, as16-1 and ca17-1 showed high h ...	2004	15522509
phylogenetic relationships of non-mitochondrial nucleotide transport proteins in bacteria and eukaryotes.	current knowledge about the nucleotide metabolism of intracellular bacteria is very limited. here we report on the identification of nucleotide transport proteins (ntt) of two obligate endoparasites, caedibacter caryophila and holospora obtusa, both alpha-proteobacteria, which reside in the vegetative macronucleus of paramecium caudatum. for comparative studies, we also identified the first nucleotide transporter in chloroplasts of a red alga, i.e. galdieria sulphuraria, and further homologs in ...	2003	12657464
the endosymbiotic bacterium holospora obtusa enhances heat-shock gene expression of the host paramecium caudatum.	the bacterium holospora obtusa is a macronuclear-specific symbiont of the ciliate paramecium caudatum. h. obtusa-bearing paramecia could survive even after the cells were quickly heated from 25 degrees c to 35 degrees c. to determine whether infection with h. obtusa confers heat shock resistance on its host, we isolated genes homologous to the heat shock protein genes hsp60 and hsp70 from p. caudatum. the deduced amino acid sequences of both cdnas were highly homologous to hsp family sequences f ...	2003	15132173
novel bacterial endosymbionts of acanthamoeba spp. related to the paramecium caudatum symbiont caedibacter caryophilus.	acanthamoebae are increasingly being recognized as hosts for obligate bacterial endosymbionts, most of which are presently uncharacterized. in this study, the phylogeny of three gram-negative, rod-shaped endosymbionts and their acanthamoeba host cells was analysed by the rrna approach. comparative analyses of 16s rdna sequences retrieved from amoebic cell lysates revealed that the endosymbionts of acanthamoeba polyphaga hn-3, acanthamoeba sp. uwc9 and acanthamoeba sp. uwe39 are related to the pa ...	1999	11207753
effects of antibiotics on the early infection process of a macronuclear endosymbiotic bacterium holospora obtusa of paramecium caudatum.	we examined the effects of antibiotics involved in bacterial dna, rna and protein synthesis and host protein synthesis on the early infection process of the bacterium holospora obtusa, a macronucleus-specific symbiont of the ciliate paramecium caudatum. infection of the host macronucleus by the bacterium was not inhibited by mitomycin c, rifampicin and chloramphenicol. however, ingestion of the bacterium into the host digestive vacuoles and escape of the bacterium from the vacuoles to the host c ...	1999	10518753
structure and expression of a groe-homologous operon of a macronucleus-specific symbiont holospora obtusa of the ciliate paramecium caudatum.	the reproductive form of a macronucleus-specific symbiont holospora obtusa, when harbored by the macronucleus of the ciliate paramecium caudatum, selectively synthesized a 63-kda protein which is immunologically related to groel, or hsp60, of escherichia coli. heat shock treatment of isolated cells of the reproductive and infectious form of the bacterium also induced the synthesis of the groel homolog. immunoblotting showed that the amount of this protein per cell, whether the reproductive or in ...	1998	9495035
cloning and sequencing of gene coding for a periplasmic 5.4 kda peptide of the macronucleus-specific symbiont holospora obtusa of the ciliate paramecium caudatum.	we purified a 5.4 kda peptide which is present in the intermediate and infectious form, but not in the reproductive form of a symbiotic bacterium holospora obtusa of the ciliate paramecium caudatum. sequencing of its gene revealed that it encodes a peptide composed of 49 amino acids, and that the peptide is preceded by a putative signal peptide of 19 amino acids. we determined the transcription start point for the gene by primer extension analysis, indicating that the transcription starts with a ...	1997	9200981
quantitative changes in periplasmic proteins of the macronucleus-specific bacterium holospora obtusa in the infection process of the ciliate paramecium caudatum.	the gram-negative bacterium holospora obtusa is a macronucleus-specific symbiont of the ciliate paramecium caudatum. the infectious form of this bacterium infects the host macronucleus through digestive vacuoles and differentiates into the reproductive form two days after the infection in the nucleus. the monoclonal antibodies if-3-1 and if-3-2 reacted with 39 and 15 kda periplasmic proteins, respectively, that were specific for the infectious form of h. obtusa. because the antigens were not det ...	1997	9435135
molecular phylogeny and in situ detection of the etiologic agent of necrotizing hepatopancreatitis in shrimp.	necrotizing hepatopancreatitis (nhp) is a severe disease of farm-raised penaeus vannamei that has been associated with mortality losses ranging from 20 to 95%. nhp was first recognized in texas in 1985 (s. k. johnson, p. 16, in handbook of shrimp diseases, 1989) and is an economically important disease that has limited the ability to culture shrimp in texas. the putative cause of nhp is a gram-negative, pleomorphic, intracellular, rickettsia-like bacterium that remains uncultured in part because ...	1996	8795235
monoclonal antibody to a bacterial endonuclear symbiont holospora cross reacts with proteins of contractile vacuole radial canals of paramecium species.	a monoclonal antibody (mab) ir-2-1 was raised against a 67-kda protein purified from the macronucleus-specific bacterial symbiont holospora obtusa of paramecium caudatum. the mab was found to react with two bands (31 and 67-kda) on gels of h. obtusa. indirect immunofluorescence microscopy showed that these antigens were distributed inside the cells. however, unexpectedly, this mab also cross reacted with the radial arms of the contractile vacuole in p. caudatum, p. tetraurelia, p. multimicronucl ...	1994	7804254
occurrence of fragmented 16s rrna in an obligate bacterial endosymbiont of paramecium caudatum.	the phylogenetic position of caedibacter caryophila, a so far noncultured killer symbiont of paramecium caudatum, was elucidated by comparative sequence analysis of in vitro amplified 16s rrna genes (rdna). c. caryophila is a member of the alpha subclass of the proteobacteria phylum. within this subclass c. caryophila is moderately related to holospora obtusa, which is another obligate endosymbiont of paramecium caudatum, and to rickettsia. a 16s rrna targeted specific hybridization probe was de ...	1993	8234331
sensitivity of the infectious long form of the macronuclear endosymbiont holospora obtusa of the ciliate paramecium caudatum against chemical and physical factors.	effects of various temperatures, phs and drugs on the morphology, infectivity to the macronucleus of paramecium caudatum (ability to penetrate macronuclear membrane), and reproductive ability of the infectious long form of holospora obtusa were examined. the infectivity was not lost between ph 3-12, suggesting that acidosomal fusion with the bacteria-bearing food vacuoles does not inactivate the bacterial infectivity because ph in the food vacuoles at the maximum acidification has been known to ...	1991	23194703
identification and localization of major stage-specific polypeptides of infectious holospora obtusa with monoclonal antibodies.	with the help of monoclonal antibodies (mabs) we investigated the occurrence of six polypeptides throughout parts of the life cycle of holospora obtusa, a bacterium infecting the macronucleus of the ciliate paramecium caudatum. the polypeptides of interest formed major bands in the protein pattern of the infectious form (if) of h. obtusa. all mabs used recognized individual polypeptide bands of the if proteins separated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. three polypept ...	1991	1856177
changes in fine structure and polypeptide pattern during development of holospora obtusa, a bacterium infecting the macronucleus of paramecium caudatum.	the development of the bacterium holospora obtusa, which infects the macronucleus of paramecium caudatum, was investigated in the course of a new infection from the infectious form into the reproductive form and vice versa. in parallel with a complete structural reorganization of the bacterium, the protein pattern changed gradually in this development. during the differentiation of the infectious form into the reproductive form, the voluminous periplasm was gradually reduced and the cytoplasm ex ...	1990	2211504
infection and maintenance of holospora obtusa, a macronucleus-specific bacterium of the ciliate paramecium caudatum.	the gram-negative bacterium holospora obtusa is a macronucleus-specific symbiont of the ciliate paramecium caudatum, which invades the host cell via a food vacuole, infects its macronucleus and grows exclusively in the nucleus. from infection experiments, we showed that a property of the macronucleus that is necessary for it to be recognized and infected by h. obtusa is commonly provided by p. caudatum, p. multimicronucleatum and 14 species of the p. aurelia complex, but not by p. jenningsi, p. ...	1985	3905836
isolation and characterization of macronuclei of paramecium caudatum infected with the macronucleus-specific bacterium holospora obtusa.	macronuclei from paramecium caudatum infected with holospora obtusa may be isolated on sucrose step gradients. macronuclei containing primarily infectious forms can be separated from those bearing predominantly reproductive forms. rna polymerase activity in infected macronuclei is greater by a factor of 5 than that in uninfected macronuclei. proteinase activity is also significantly higher.	1985	3894389
infection of macronuclear anlagen of paramecium caudatum with the macronucleus-specific symbiont holospora obtusa.	the gram-negative bacterium holospora obtusa is an endonuclear symbiont of paramecium caudatum, which is incorporated into the host cells via the food vacuoles and infects their macronucleus exclusively, but never the micronucleus. since these two kinds of nuclei originate from a fertilization nucleus, it is assumed that the macronucleus acquires a property necessary for it to be recognized by the bacterium at a certain time during the nuclear differentiation process. we found that this property ...	1983	6662855