Publications (4)4.67 Total impact
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Article: Environmental Chlamydiae Alter the Growth Speed and Motility of Host Acanthamoebae.
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ABSTRACT: Symbiosis between living beings is an important driver of evolutionary novelty and ecological diversity; however, understanding the mechanisms underlying obligate mutualism remains a significant challenge. Regarding this, we have previously isolated two different Acanthamoeba strains harboring endosymbiotic bacteria, Protochlamydia (R18 symbiotic amoebae: R18WT) or Neochlamydia (S13 symbiotic amoebae; S13WT). In this study, we treated the symbiotic amoebae R18WT and S13WT with doxycycline (DOX) and rifampicin (RFP), respectively, to establish the aposymbiotic amoebae R18DOX and S13RFP, respectively. Subsequently, we compared the growth speed, motility, phagocytosis, pinocytosis, and morphology of the symbiotic and aposymbiotic amoebae. The growth speed of R18DOX was decreased, although that of S13RFP was increased. A marked change in motility was observed only for R18DOX amoebae. There was no difference in phagocytic and pinocytic activities between the symbiotic and aposymbiotic amoebae. Meanwhile, we observed a significant change in the phalloidin staining pattern and morphological changes in R18DOX (but not S13RFP) aposymbiotic amoebae, indicating a change in actin accumulation upon removal of the Protochlamydia. Infection of C3 (a reference strain) or S13RFP amoebae with Protochlamydia had a harmful effect on the host amoebae, but R18DOX amoebae re-infected with Protochlamydia showed recovery in both growth speed and motility. Taken together, we conclude that endosymbiont environmental chlamydiae alter the growth speed and/or motility of their host Acanthamoeba, possibly implying an close mutual relationship between amoebae and environmental chlamydiae.Microbes and Environments 10/2012; · 1.91 Impact Factor -
Article: Ciliates rapidly enhance the frequency of conjugation between Escherichia coli strains through bacterial accumulation in vesicles.
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ABSTRACT: The mechanism underlying bacterial conjugation through protozoa was investigated. Kanamycin-resistant Escherichia coli SM10λ+ carrying pRT733 with TnphoA was used as donor bacteria and introduced by conjugation into ciprofloxacin-resistant E. coli clinical isolate recipient bacteria. Equal amounts of donor and recipient bacteria were mixed together in the presence or absence of protozoa (ciliates, free-living amoebae, myxamoebae) in Page's amoeba saline for 24 h. Transconjugants were selected with Luria broth agar containing kanamycin and ciprofloxacin. The frequency of conjugation was estimated as the number of transconjugants for each recipient. Conjugation frequency in the presence of ciliates was estimated to be approximately 10⁻⁶, but in the absence of ciliates, or in the presence of other protozoa, it was approximately 10⁻⁸. Conjugation also occurred in culture of ciliates at least 2 h after incubation. Successful conjugation was confirmed by the polymerase chain reaction. Addition of cycloheximide or latrunculin B resulted in suppression of conjugation. Heat killing the ciliates or bacteria had no effect on conjugation frequency. Co-localization of green fluorescent protein-expressing E. coli and PKH-67-vital-stained E. coli was observed in the same ciliate vesicles, suggesting that both donor and recipient bacteria had accumulated in the same vesicle. In this study, the conjugation frequency of bacteria was found to be significantly higher in vesicles purified from ciliates than those in culture suspension. We conclude that ciliates rapidly enhance the conjugation of E. coli strains through bacterial accumulation in vesicles.Research in Microbiology 10/2010; 161(8):711-9. · 2.76 Impact Factor -
Article: Endosymbiotic bacterium Protochlamydia can survive in acanthamoebae following encystation
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ABSTRACT: Whether endosymbionts can survive amoebal encystations remains a significant challenge in cellular biology. The survival of the endosymbiotic bacteria Protochlamydia belonging to environmental chlamydiae in acanthamoebae following encystation was therefore assessed. The bacteria were observed in cysts and the bacterial transcripts (16S rRNA and/or groEL) were also detected in amoeba cultures following encystation. Furthermore, the bacterial replication and the growth was confirmed in trophozoites reverted from cysts. Thus, these results demonstrated that Protochlamydia could survive in acanthamoebae following encystation. Our findings suggest that amoeba cysts might be further studied in order to elucidate the their role in the environmental survival of endosymbionts. -
Article: Survival and transfer ability of phylogenetically diverse bacterial endosymbionts in environmental Acanthamoeba isolates
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ABSTRACT: Obligate intracellular bacteria are commonly found as endosymbionts of acanthamoebae, however, their survival in and ability to transfer to amoebae are currently uncharacterized. In this study, six bacterial endosymbionts, found in five environmental Acanthamoeba isolates (S13, R18, S23, S31, S40) from different locations of Sapporo city, Japan, were characterized. Phylogenetic analysis revealed that three-bacterial endosymbionts (eS31, eS40a, eS23) belonged to α- and β-Proteobacterium phyla and the remaining endosymbionts (eR18, eS13, eS40b) belonged to the Chlamydiales phylum. The Acanthamoeba isolate (S40) contained two phylogenetically different bacterial endosymbionts (eS40a, eS40b). Fluorescent in situ hybridization analysis showed that all bacterial endosymbionts were diffusely localized within amoebae. Transmission electron microscopy also showed that the endosymbionts were rod-shaped (eS31, eS40a, eS23) or sphere- or crescent-shaped (eR18, eS13, eS40b). No successful culture of these bacteria was achieved using conventional culture methods, but the viability of endosymbionts was confirmed by live/dead staining and RT-PCR methods. However, endosymbionts (except eR18) derived from original host cells lost the ability to be transferred to another amoeba strain (Acanthamoebae ATCC C3). Taken together, our data demonstrate that phylogenetically diverse bacterial endosymbionts found in amoebae are viable and maintain a stable interaction with amoebae.
