Publications by authors named "Kensuke Igarashi"

35 Publications

Complete Genome Sequence of Bacterium Strain SO-S41, Isolated from Forest Soil.

Microbiol Resour Announc 2021 Jul 22;10(29):e0053621. Epub 2021 Jul 22.

Graduate School of Agriculture, Hokkaido University, Sapporo, Hokkaido, Japan.

The complete genome of hydrogen peroxide-sensitive alphaproteobacterial strain SO-S41 was sequenced. The complete genome contains a single chromosome, is 4,443,179 bp in length, contains a total of 4,632 genes, and has a G+C content of 66.2%.
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http://dx.doi.org/10.1128/MRA.00536-21DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8297455PMC
July 2021

Peri-implant tissue augmentation by volume-stable collagen matrix transplantation: a study of dog mandibles.

Odontology 2021 Jul 19. Epub 2021 Jul 19.

Department of Crown and Bridge Prosthodontics, The Nippon Dental University School of Life Dentistry at Niigata, 1-8 Hamauracho, Chuo-ku, Niigata, 951-8580, Japan.

The aim of this study was to investigate histologically the amount of peri-implant tissue augmentation after volume-stable porcine collagen matrix transplantation. Six male beagle dogs were used in the experiment. P2, P4, and M1 distal roots were extracted under general anesthesia. After 6 months, implants were placed in the same sites, and volume-stable porcine collagen matrix transplantation was performed. Impressions were taken at 1 and 2 weeks and at 1, 2, and 3 months after transplantation. The dogs were euthanized at 3 months, and their mandibles were removed and scanned using micro-computed tomography. Standard Triangulated Language data were also obtained. Using preoperative models as a reference, the data for all time points were compared, and changes in the thickness of the cross-section of the implant sites were measured. The model created at 3 months was then compared with the mandible data, and the thickness of collected peri-implant soft tissue was measured under optical microscopy. Increased thickness was found at some of the sites on the buccal side. Regarding the peri-implant soft tissue, the thickness of the measured sites on the buccal side was significantly increased at 3 months in the experimental group. Histological observations of the internal structures of the tissue in the experimental group revealed irregular collagen fibers and a remnant collagen matrix. Endogenous tissue was observed within the collagen matrix, indicating good fusion with the surrounding autologous tissue. These results suggest that volume-stable porcine collagen matrix transplantation promotes peri-implant tissue augmentation on the buccal side.
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http://dx.doi.org/10.1007/s10266-021-00639-8DOI Listing
July 2021

Retention forces between primary and secondary CAD/CAM manufactured telescopic crowns: an in vitro comparison of common material combinations.

Clin Oral Investig 2021 Apr 8. Epub 2021 Apr 8.

Section for Digital Implant- and Reconstructive Dentistry [DIRecD], Department of Reconstructive Dentistry and Gerodontology, School of Dental Medicine, University of Bern, Freiburgstrasse 7, 3010, Bern, Switzerland.

Objectives: To analyze the retention forces between primary and secondary telescopic crowns milled from various materials and to compare them with the retention forces between cast telescopic crowns made of precious metal alloys.

Materials And Methods: Primary and secondary crowns (N = 60; n = 10 per group) were fabricated using various material combinations (1: zirconia [ZIR]/polyether ether ketone [PEEK]; 2: titanium grade IV [TI]/PEEK; 3: PEEK/PEEK; 4: non-precious alloy [NPA]/PEEK; 5:NPA/NPA), while precious alloy (PA) was used for the control group (6: PA/PA). The retention forces at 10, 1000, 5000, and 10,000 connection and disconnection cycles and the relative weights were analyzed, applying nonparametric repeated measures ANOVA and post hoc Mann-Whitney and Wilcoxon signed-rank tests (α < 0.05).

Results: Globally, significant differences in the retention forces among the materials (p < 0.0001), time points (p < 0.0001), and wear resistance for the various materials (p < 0.0001) were observed. No significant changes in retention forces compared to baseline were observed in groups 2, 4, 5, and 6. A significantly higher weight loss for both primary and secondary crowns was observed in groups 4 and 6.

Conclusions: The material combination in telescopic attachments influences retention forces and wear. Interactions between materials and time were evident, indicating that the change in retention forces differs among the materials. The combinations of milled TI/PEEK and NPA/NPA qualify for further preclinical testing in a more clinically realistic setup, determining a material-specific double-crown design.

Clinical Relevance: The design of precious alloy telescopic crowns cannot be directly transferred to other milled material combinations due to different retention behaviors.
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http://dx.doi.org/10.1007/s00784-021-03928-2DOI Listing
April 2021

CBCT imaging and histopathological characteristics of osteoradionecrosis and medication-related osteonecrosis of the jaw.

Imaging Sci Dent 2021 Mar 29;51(1):73-80. Epub 2021 Jan 29.

Department of Oral and Maxillofacial Surgery, The Nippon Dental University School of Life Dentistry at Niigata, Niigata, Japan.

Purpose: The purpose of this study was to evaluate the cone-beam computed tomographic (CBCT) imaging and histopathological characteristics of osteoradionecrosis (ORN) and medication-related osteonecrosis of the jaw (MRONJ).

Materials And Methods: Ten surgical specimens from segmental mandibulectomy (3 ORN and 7 MRONJ) were analyzed using CBCT. The CBCT parameters were as follows: high-resolution mode (tube voltage, 90.0 kV; tube current, 4.00 mA; rotation time, 16.8 s; field of view, 56 mm×56 mm; thickness, 0.099 mm). Histopathological characteristics were evaluated using histological slides of the surgical specimens. The Pearson chi-square test was used to compare ORN and MRONJ in terms of CBCT findings (internal texture, sequestrum, periosteal reaction and cortical perforation) and histopathological characteristics (necrotic bone, inflammatory cells, reactive bone formation, bacteria, , and osteoclasts). A value less than 0.05 was considered to indicate statistical significance.

Results: MRONJ showed periosteal reaction on CBCT more frequently than ORN (7 of 7 [100%] vs. 0 of 3 [0%], <0.05). Regarding histopathological characteristics, MRONJ showed osteoclasts more frequently than ORN (6 of 7 [85.7%] vs. 0 of 3 [0%], <0.05).

Conclusion: This study evaluated the CBCT imaging and histopathological characteristics of ORN and MRONJ, and the findings suggest that CBCT could be useful for the evaluation of ORN and MRONJ.
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http://dx.doi.org/10.5624/isd.20200230DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8007393PMC
March 2021

Vertical eruption of anterior maxillary teeth adjacent to single-implant-supported crowns: An assessment after a 3-year follow-up period.

J Prosthet Dent 2021 Mar 4. Epub 2021 Mar 4.

Full Professor, Department of Oral Implantology and Prosthetic Dentistry, ACTA, University of Amsterdam and VU University, Amsterdam, the Netherlands.

Statement Of Problem: Vertical eruption of teeth adjacent to an implant has been reported clinically and might affect the esthetic outcome over time. The prevalence of the problem is unclear.

Purpose: The purpose of this prospective clinical trial was to evaluate the vertical eruption of anterior maxillary teeth adjacent to single-implant crowns after a 3-year follow-up period.

Material And Methods: Thirty single dental implants were inserted in maxillary anterior sites including the first premolar. The mean age of the participants at implant-supported crown insertion was 48.4 years (range 23 to 79 years). Each implant was restored with a 1-piece screw-retained ceramic single crown. The vertical changes of 60 adjacent anterior maxillary teeth were evaluated from periapical radiographs and casts at baseline, 6, 12, and 36 months.

Results: A global ANOVA test showed statistically significant differences for the outcomes of the distance-implant platform and cement-enamel junction (DPC) (P<.001), crown length distal (P=.021) and mesial (P=.035), implant crown length (P=.022), and incisal edge to edge (P<.001).

Conclusions: Continuous vertical tooth eruption next to a single dental implant was observed in adult participants.
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http://dx.doi.org/10.1016/j.prosdent.2020.07.040DOI Listing
March 2021

Reductive Transformation of Fe(III) (oxyhydr)Oxides by Mesophilic Homoacetogens in the Genus .

Front Microbiol 2021 1;12:600808. Epub 2021 Feb 1.

Bioproduction Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Sapporo, Japan.

Microbial reduction of iron contributes to the dissolution and transformation of iron-containing minerals in nature. Diverse groups of homoacetogenic bacteria (homoacetogens) have been reported to reduce insoluble Fe(III) oxides, such as hydrous ferric oxide (HFO), an Fe(III) mineral commonly found in soils and sediments. Several members of genus reportedly oxidize Fe(0), indicating the presence of an extracellular electron-uptake mechanism. However, the ability of the genus to reduce insoluble Fe(III) oxides is limited, and the underlying reduction mechanism remains to be elucidated. In this study, the HFO reduction ability of three spp. ( sp. strain GT1, , and ) and a homoacetogen of a different genus () were assayed under organotrophic (ethanol) and lithotrophic (H + CO) conditions without a chelator or reducing reagent. All tested homoacetogens showed acetogenic growth and concomitant reduction of HFO under both organotrophic and lithotrophic conditions. Analysis of the growth stoichiometry showed that Fe(III) reduction does not support direct energy conservation, thereby indicating that Fe(III) reduction is a side reaction of acetogenesis to dissipate the excess reducing power. HFO was reduced to a soluble Fe(II) form by microbial activity. In addition, we observed that strain GT1, , and reduced crystalline Fe(III) oxides, and HFO was reductively transformed into magnetite (FeO) under phosphate-limiting conditions. Separation of HFO by a dialysis membrane still permitted Fe(II) production, although the reduction rate was decreased, suggesting that Fe(III) reduction is at least partially mediated by soluble redox compound(s) secreted from the cells. Finally, culture experiments and comparative genomic analysis suggested that electron transfer by flavins and multiheme -type cytochrome were not directly correlated with Fe(III) reduction activity. This study reveals the capability of spp. in the reductive transformation of iron mineral and indicates the potential involvement of these organisms in iron and other mineral cycles in nature.
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http://dx.doi.org/10.3389/fmicb.2021.600808DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7901989PMC
February 2021

An iron corrosion-assisted H-supplying system: a culture method for methanogens and acetogens under low H pressures.

Sci Rep 2020 11 5;10(1):19124. Epub 2020 Nov 5.

Bioproduction Research Institute, AIST, 1-1-1 Higashi, Tsukuba, 305-8567, Japan.

H is an important fermentation intermediate in anaerobic environments. Although H occurs at very low partial pressures in the environments, the culture and isolation of H-utilizing microorganisms is usually carried out under very high H pressures, which might have hampered the discovery and understanding of microorganisms adapting to low H environments. Here we constructed a culture system designated the "iron corrosion-assisted H-supplying (iCH) system" by connecting the gas phases of two vials (one for the iron corrosion reaction and the other for culturing microorganisms) to achieve cultures of microorganisms under low H pressures. We conducted enrichment cultures for methanogens and acetogens using rice paddy field soil as the microbial source. In the enrichment culture of methanogens under canonical high H pressures, only Methanobacterium spp. were enriched. By contrast, Methanocella spp. and Methanoculleus spp., methanogens adapting to low H pressures, were specifically enriched in the iCH cultures. We also observed selective enrichment of acetogen species by the iCH system (Acetobacterium spp. and Sporomusa spp.), whereas Clostridium spp. predominated in the high H cultures. These results demonstrate that the iCH system facilitates culture of anaerobic microorganisms under low H pressures, which will enable the selective culture of microorganisms adapting to low H environments.
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http://dx.doi.org/10.1038/s41598-020-76267-zDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7645788PMC
November 2020

Single versus splinted short implants at sinus augmented sites: A systematic review and meta-analysis.

J Stomatol Oral Maxillofac Surg 2021 06 28;122(3):303-310. Epub 2020 Sep 28.

Department of Reconstructive Dentistry & Gerodontology, School of Dental Medicine, Faculty of Medicine, University of Bern, 3010 Bern, Switzerland; Department of Life Science Dentistry, The Nippon Dental University, Niigata 951-8580, Japan.

Objective: This review primarily evaluated the success, survival and failure rates of implants shorter than 10 mm restored with single-unit or splinted fixed dental prostheses in maxillary sinus augmented sites.

Material And Methods: Two reviewers independently performed the systematic search of electronic databases, including MEDLINE, EMBASE and CENTRAL, up to September 2019 with no language restriction. A supplemental hand search consisted of screening 13 journals. The inclusion criteria were: primary studies reporting implant, prosthetic and patient-reported outcome measures (PROMs) of extra-short and short implants placed in conjunction with sinus floor elevation in partially dentate patients, restored with single- and splinted-crowns for direct comparison, with a minimal 1-year follow-up. Weighted arithmetic mean (WAM) of the implant survival was performed according to the type of prosthesis. This was confirmed by using Review Manager software to perform meta-analysis.

Results: Two observational studies reporting on 106 tapered, press-fit, sintered porous-surfaced implants with a length ranging from 5 mm to 9 mm were included in this systematic review. Of these, 20 and 86 implants were restored with single and splinted prostheses, respectively. The risk ratio (RR) was 1.16 (95% CI: .31-4.30, p = .58, I² = 0%) for individually restored implants failure when compared to splinted implants, indicating that short dental implants restored with single crowns could have a 16% higher possibility of failure if compared to implants with splinted crowns. The heterogeneity value was not statistically significative (p = .58). No statistical difference in the implant survival rate of the two types of analysed prostheses was observed after WAM (p= .923). The level of evidence for the included studies ranged from low (4) to fair (2B).

Conclusion: Similar clinical outcomes up to a 9-year follow-up were observed in single and splinted porous-surfaced implants shorter than 10 mm located in sites with sinus lift. However, the conclusion shall be interpreted with caution due to the level of evidence and limited number of included studies included in this systematic review.
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http://dx.doi.org/10.1016/j.jormas.2020.08.013DOI Listing
June 2021

Microbial Community Analysis of Anaerobic Enrichment Cultures Supplemented with Bacterial Peptidoglycan as the Sole Substrate.

Microbes Environ 2020 ;35(3)

Division of Applied Bioscience, Graduate School of Agriculture, Hokkaido University.

Methanogenic microbial communities were enriched from rice paddy soil and anaerobic digester sludge using peptidoglycan purified from gram-negative Escherichia coli or gram-positive Micrococcus luteus as the sole substrate. Methane production data suggested the anaerobic degradation of peptidoglycan and also that peptidoglycan from E. coli had lower degradability. The community structures of enrichment cultures fed peptidoglycan from E. coli or M. luteus were similar, but distinctly different. A number of phylogenetically novel and uncultured bacteria, particularly in the phyla Bacteroidetes, WWE1, Armatimonadetes, and Verrucomicrobia, dominated the enrichment cultures, suggesting their involvement in anaerobic peptidoglycan degradation.
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http://dx.doi.org/10.1264/jsme2.ME20002DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7511781PMC
March 2021

Variability in tongue pressure among elderly and young healthy cohorts: A systematic review and meta-analysis.

J Oral Rehabil 2021 Apr 15;48(4):430-448. Epub 2020 Sep 15.

Department of Reconstructive Dentistry and Gerodontology, School of Dental Medicine, University of Bern, Bern, Switzerland.

Objectives: Tongue pressure (TP) is used for the diagnosis of oral hypofunction; however, the impact of several variables on TP is unclear. Therefore, the current systematic review and meta-analysis aimed to analyse the variability in tongue pressure among healthy individuals aged ≥60 years vs <60 years. Secondary outcomes were the influence of gender and the type of measuring device (Iowa Oral Performance Instrument (IOPI) vs JMS tongue pressure measurement device (JMS)).

Methods: PubMed and the Japanese database Ichushi-Web were searched systematically by two independent reviewers for studies reporting TP values in healthy populations. Clinical studies published between 1959 and June 2020 with more than 10 participants, written in English, German or Japanese, were included. A random-effects meta-regression for aggregate-level data was applied (α < 0.05).

Results: Sixty-eight studies reported TP for a total of 13 773 subjects aged <60 years (n = 3265) and ≥60 years (n = 10 508). TP was significantly higher in subjects <60 years (estimated weighted mean (EWM) ± standard error = 51.9 ± 1.28 kPa; 95% CI = 49.4-54.4) relative to those ≥60 (EWM = 34.7 ± 0.94 kPa; 95% CI = 32.8-36.5) (P < .001), men (EWM = 45.9 ± 2.09 kPa; 95% CI = 41.8-50.0) relative to women (EWM = 39.3 ± 1.68 kPa; 95% CI = 36.0-42.6) (P = .015) and when assessed with the IOPI (EWM = 51.9 ± 1.32 kPa; 95% CI = 49.3-54.5) compared to the JMS (EWM = 33.5 ± 0.63 kPa; 95% CI = 32.2-34.7) (P < .001). In terms of gender, there was no significant difference in TP among subjects ≥60 years (P = .282). However, in subjects younger than 60, a significant difference was observed (P = .004).

Conclusions: Healthy populations aged <60 years showed significantly higher TP than those aged ≥60 years. TP values ascertained by the IOPI are significantly higher than those obtained with the JMS.
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http://dx.doi.org/10.1111/joor.13076DOI Listing
April 2021

A hydrogen-dependent geochemical analogue of primordial carbon and energy metabolism.

Nat Ecol Evol 2020 04 2;4(4):534-542. Epub 2020 Mar 2.

Institute for Molecular Evolution, University of Düsseldorf, Düsseldorf, Germany.

Hydrogen gas, H, is generated by alkaline hydrothermal vents through an ancient geochemical process called serpentinization, in which water reacts with iron-containing minerals deep within the Earth's crust. H is the electron donor for the most ancient and the only energy-releasing route of biological CO fixation, the acetyl-CoA pathway. At the origin of metabolism, CO fixation by hydrothermal H within serpentinizing systems could have preceded and patterned biotic pathways. Here we show that three hydrothermal minerals-greigite (FeS), magnetite (FeO) and awaruite (NiFe)-catalyse the fixation of CO with H at 100 °C under alkaline aqueous conditions. The product spectrum includes formate (up to 200 mM), acetate (up to 100 µM), pyruvate (up to 10 µM), methanol (up to 100 µM) and methane. The results shed light on both the geochemical origin of microbial metabolism and the nature of abiotic formate and methane synthesis in modern hydrothermal vents.
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http://dx.doi.org/10.1038/s41559-020-1125-6DOI Listing
April 2020

Thermotogales origin scenario of eukaryogenesis.

J Theor Biol 2020 05 7;492:110192. Epub 2020 Feb 7.

Bioproduction Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Sapporo 062‒8517, Hokkaido, Japan.

How eukaryotes were generated is an enigma of evolutionary biology. Widely accepted archaeal-origin eukaryogenesis scenarios, based on similarities of genes and related characteristics between archaea and eukaryotes, cannot explain several eukaryote-specific features of the last eukaryotic common ancestor, such as glycerol-3-phosphate-type membrane lipids, large cells and genomes, and endomembrane formation. Thermotogales spheroids, having multicopy-integrated large nucleoids and producing progeny in periplasm, may explain all of these features as well as endoplasmic reticulum-type signal cleavage sites, although they cannot divide. We hypothesize that the progeny chromosome is formed by random joining small DNAs in immature progeny, followed by reorganization by mechanisms including homologous recombination enabled with multicopy-integrated large genome (MILG). We propose that Thermotogales ancestor spheroids came to divide owing to the archaeal cell division genes horizontally transferred via virus-related particles, forming the first eukaryotic common ancestor (FECA). Referring to the hypothesis, the archaeal information-processing system would have been established in FECA by random joining DNAs excised from the MILG, which contained horizontally transferred archaeal and bacterial DNAs, followed by reorganization by the MILG-enabled homologous recombination. Thus, the large genome may have been a prerequisite, but not a consequence, of eukaryogenesis. The random joining of DNAs likely provided the basic mechanisms for eukaryotic evolution: producing the diversity by the formations of supergroups, novel genes, and introns that are involved in exon shuffling.
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http://dx.doi.org/10.1016/j.jtbi.2020.110192DOI Listing
May 2020

Isolation and Genomic Characterization of a Proteobacterial Methanotroph Requiring Lanthanides.

Microbes Environ 2020 ;35(1)

Bioproduction Research Institute, National Institute of Advanced Industrial Science and Technology (AIST).

Although the bioavailability of rare earth elements (REEs, including scandium, yttrium, and 15 lanthanides) has not yet been examined in detail, methane-oxidizing bacteria (methanotrophs) were recently shown to harbor specific types of methanol dehydrogenases (XoxF-MDHs) that contain lanthanides in their active site, whereas their well-characterized counterparts (MxaF-MDHs) were Ca-dependent. However, lanthanide dependency in methanotrophs has not been demonstrated, except in acidic environments in which the solubility of lanthanides is high. We herein report the isolation of a lanthanide-dependent methanotroph from a circumneutral environment in which lanthanides only slightly dissolved. Methanotrophs were enriched and isolated from pond sediment using mineral medium supplemented with CaCl or REE chlorides. A methanotroph isolated from the cerium (Ce) chloride-supplemented culture, Methylosinus sp. strain Ce-a6, was clearly dependent on lanthanide. Strain Ce-a6 only required approximately 30 nM lanthanide chloride for its optimal growth and exhibited the ability to utilize insoluble lanthanide oxides, which may enable survival in circumneutral environments. Genome and gene expression analyses revealed that strain Ce-a6 lost the ability to produce functional MxaF-MDH, and this may have been due to a large-scale deletion around the mxa gene cluster. The present results provide evidence for lanthanide dependency as a novel survival strategy by methanotrophs in circumneutral environments.
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http://dx.doi.org/10.1264/jsme2.ME19128DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7104280PMC
March 2020

Direct Interspecies Electron Transfer Mediated by Graphene Oxide-Based Materials.

Front Microbiol 2019 17;10:3068. Epub 2020 Jan 17.

Bioproduction Research Institute, National Institute of Advanced Industrial Science and Technology, Sapporo, Japan.

Conductive materials are known to promote direct interspecies electron transfer (DIET) by electrically bridging microbial cells. Previous studies have suggested that supplementation of graphene oxide (GO) based materials, including GO, and reduced GO (rGO), to anaerobic microbial communities, can promote DIET. This promotion mechanism is thought to be involved in electron transfer via rGO or biologically formed rGO. However, concrete evidence that rGO directly promotes DIET is still lacking. Furthermore, the effects of the physicochemical properties of GO-based materials on DIET efficiency have not been elucidated. In the current work, we investigated whether chemically and biologically reduced GO compounds can promote DIET in a defined model coculture system, and also examined the effects of surface properties on DIET-promoting efficiency. Supplementation of GO to a defined DIET coculture composed of an ethanol-oxidizing electron producer and a methane-producing electron consumer promoted methane production from ethanol. X-ray photoelectron spectroscopy revealed that GO was reduced to rGO during cultivation by activity. The stoichiometry of methane production from ethanol and the isotope labeling experiments clearly showed that biologically reduced GO induced DIET-mediated syntrophic methanogenesis. We also assessed the DIET-promoting efficiency of chemically reduced GO and its derivatives, including hydrophilic amine-functionalized rGO (rGO-NH) and hydrophobic octadecylamine-functionalized rGO (rGO-ODA). While all tested rGO derivatives induced DIET, the rGO derivatives with higher hydrophilicity showed higher DIET-promoting efficiency. Optical microscope observation revealed that microbial cells, in particular, , more quickly adhered to more hydrophilic GO-based materials. The superior ability to recruit microbial cells is a critical feature of the higher DIET-promoting efficiency of the hydrophilic materials. This study demonstrates that biologically and chemically reduced GO can promote DIET-mediated syntrophic methanogenesis. Our results also suggested that the surface hydrophilicity (i.e., affinity toward microbial cells) is one of the important determinants of the DIET-promoting efficiencies. These observations will provide useful guidance for the selection of conductive particles for the improvement of methanogenesis in anaerobic digesters.
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http://dx.doi.org/10.3389/fmicb.2019.03068DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6978667PMC
January 2020

Computer programme to assess mandibular cortex morphology in cases of medication-related osteonecrosis of the jaw with osteoporosis or bone metastases.

Imaging Sci Dent 2019 Dec 24;49(4):281-286. Epub 2019 Dec 24.

Department of Oral Radiology, Asahi University School of Dentistry, Mizuho, Japan.

Purpose: The purpose of this study was to evaluate the morphology of the mandibular cortex in cases of medication-related osteonecrosis of the jaw (MRONJ) in patients with osteoporosis or bone metastases using a computer programme.

Materials And Methods: Fifty-four patients with MRONJ (35 with osteoporosis and 19 with bone metastases) were examined using panoramic radiography. The morphology of the mandibular cortex was evaluated using a computer programme that scanned the mandibular inferior cortex and automatically assessed the mandibular cortical index (MCI) according to the thickness and roughness of the mandibular cortex, as follows: normal (class 1), mildly to moderately eroded (class 2), or severely eroded (class 3). The MCI classifications of MRONJ patients with osteoporosis or bone metastases were evaluated with the Pearson chi-square test. In these analyses, a 5% significance level was used.

Results: The MCI of MRONJ patients with osteoporosis (class 1: 6, class 2: 15, class 3: 14) tended to be higher than that of patients with bone metastases (class 1: 14, class 2: 5, class 3: 0) (=0.000).

Conclusion: The use of a computer programme to assess mandibular cortex morphology may be an effective technique for the objective and quantitative evaluation of the MCI in MRONJ patients with osteoporosis or bone metastases.
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http://dx.doi.org/10.5624/isd.2019.49.4.281DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6941839PMC
December 2019

Single-staged implant placement using the bone ring technique with and without membrane placement: Micro-CT analysis in a preclinical in vivo study.

Clin Oral Implants Res 2020 Jan 1;31(1):29-36. Epub 2019 Oct 1.

Department of Cranio-Maxillofacial Surgery, Inselspital, Bern University Hospital, and University of Bern, Bern, Switzerland.

Objectives: To assess the impact of collagen membrane application on bone formation surrounding implants placed simultaneously with the bone ring technique.

Material And Methods: Dental implants were inserted simultaneously with the bone ring technique in standardized, vertical alveolar bony defects in the mandible of dogs. On one side of the mandible, the augmented sites were covered with a collagen membrane (M-Group). On the contralateral side, no membranes were used (NM-Group). Implants were left to heal with osseointegration for three and six months. The harvested samples were analyzed by means of micro-CT.

Results: A nonparametric analysis of data revealed that the membranes were not a significant negative factor for bone volume (BV), but for bone-to-implant contact (BIC, p = .04). Absence of healing caps impaired BV (p = .04) and BIC (p = .02) as well. Furthermore, loss of healing caps and exposure to the oral environment significantly and negatively affected BV (p < .001) and bone mineral density (p < .05) within 2 mm below the implant shoulder. Implant exposure and healing time had a negative interaction effect on both BV (p = .01) and BIC (p = .01).

Conclusions: Within its limitations, the present study revealed no benefit of membrane application to implant placement simultaneous with the bone ring technique. Disruption of soft tissue healing was identified as a risk factor for decrease in BV and BIC.
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http://dx.doi.org/10.1111/clr.13543DOI Listing
January 2020

Characterization of the microbiota in long- and short-term natural indigo fermentation.

J Ind Microbiol Biotechnol 2019 Dec 20;46(12):1657-1667. Epub 2019 Aug 20.

Graduate School of Agriculture, Hokkaido University, Sapporo, Japan.

The duration for which the indigo-reducing state maintenance in indigo natural fermentation in batch dependent. The microbiota was analyzed in two batches of sukumo fermentation fluids that lasted for different durations (Batch 1: less than 2 months; Batch 2: nearly 1 year) to understand the mechanisms underlying the sustainability and deterioration of this natural fermentation process. The transformation of the microbiota suggested that the deterioration of the fermentation fluid is associated with the relative abundance of Alcaligenaceae. Principal coordinates analysis (PCoA) showed that the microbial community maintained a very stable state in only the long-term Batch 2. Therefore, entry of the microbiota into a stable state under alkaline anaerobic condition is an important factor for maintenance of indigo fermentation for long duration. This is the first report on the total transformation of the microbiota for investigation of long-term maintenance mechanisms and to address the problem of deterioration in indigo fermentation.
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http://dx.doi.org/10.1007/s10295-019-02223-0DOI Listing
December 2019

Quantitative SPECT/CT imaging for medication-related osteonecrosis of the jaw: a preliminary study using volume-based parameters, comparison with chronic osteomyelitis.

Ann Nucl Med 2019 Oct 24;33(10):776-782. Epub 2019 Jul 24.

Department of Oral and Maxillofacial Radiology, The Nippon Dental University School of Life Dentistry at Niigata, 1-8 Hamaura-cho, Chuo-ku, Niigata, Niigata, 951-8580, Japan.

Objective: To investigate the quantitative SPECT/CT imaging for medication-related osteonecrosis of the jaw (MRONJ) using volume-based parameters.

Methods: Thirteen patients with mandibular lesions (nine MRONJ and four chronic osteomyelitis) underwent SPECT/CT acquisition at 4 h after injection of technetium 99m hydroxymethylene diphosphonate. Then, reconstruction of the acquired data and underwent voxel-based quantitative analysis using GI-BONE software. The parameters of the quantitative manner, such as maximum standardized uptake value (SUV), peak SUV (SUV), mean SUV (SUV), metabolic bone volume (MBV) and total bone uptake (TBU), were compared for the mandibular lesions. Statistical analyses for the quantitative parameters of mandibular lesions were performed by Mann-Whitney U test. A p value lower than 0.05 was considered as statistically significant.

Results: Then, reconstruction of these quantitative parameters, SUV (10.16 ± 0.96), SUV (7.95 ± 0.88), SUV (5.90 ± 0.86) and TBU (94.22 ± 57.44) for chronic osteomyelitis were significantly higher than those for MRONJ [5.50 ± 2.47 (p = 0.020), 4.10 ± 1.85 (p = 0.011), 2.74 ± 1.07 (p = 0.006) and 29.88 ± 15.46 (p = 0.034), respectively].

Conclusions: SUV, SUV, SUV and TBU derived from bone SPECT/CT and voxel-based quantitative parameters may be useful for the evaluation of mandibular lesions, such as MRONJ and chronic osteomyelitis.
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http://dx.doi.org/10.1007/s12149-019-01390-5DOI Listing
October 2019

Performance of a repair service set for the retrieval of fractured abutment screws: a pilot in vitro study.

Int J Oral Maxillofac Implants 2019 May/June;34(3):567–573. Epub 2019 Apr 1.

Purpose: To report the success of a repair service set for the retrieval of fractured screws and to compare three clinical assessments to an in vitro assessment to verify the completeness of removal of the fractured screws.

Materials And Methods: Twelve clinicians were asked to remove fractured implant abutment screws from prepared specimens by means of a repair service set. The completeness of the removal of any abutment screw material was measured by the fit of an impression post, a dental surgery microscope, and the use of an elastomeric impression material.

Results: After the participants attempted to remove the fractured screw with the repair service set, 100%, 83.3%, 66.7%, and 75% of the fractured screws were considered successful in the impression post, dental surgery microscope, silicone replica, and stereomicroscope assessments, respectively.

Conclusion: The retrieval of fractured screws succeeded in 75% of the cases. The silicone replica technique and the dental surgery microscope had similar diagnostic values to the stereoscopic microscope assessment.
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http://dx.doi.org/10.11607/jomi.7106DOI Listing
December 2019

Draft Genome Sequence of Thermosipho globiformans Strain MN14.

Authors:
Kensuke Igarashi

Microbiol Resour Announc 2019 Feb 28;8(9). Epub 2019 Feb 28.

Bioproduction Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Sapporo, Japan.

Thermosipho globiformans strain MN14, a Gram-negative, heterotrophic, thermophilic bacterium, was isolated from a hydrothermal vent in the western Pacific Ocean. Here, I present the 1.9-Mb draft genome sequence of the strain, which consists of 75 contigs with 30.8% GC content and 1,900 predicted protein-coding genes.
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http://dx.doi.org/10.1128/MRA.01728-18DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6395878PMC
February 2019

Extracellular Electron Transfer via Outer Membrane Cytochromes in a Methanotrophic Bacterium (Bath).

Front Microbiol 2018 29;9:2905. Epub 2018 Nov 29.

Bioproduction Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Sapporo, Japan.

Electron exchange reactions between microbial cells and solid materials, referred to as extracellular electron transfer (EET), have attracted attention in the fields of microbial physiology, microbial ecology, and biotechnology. Studies of model species of iron-reducing, or equivalently, current-generating bacteria such as spp. and spp. have revealed that redox-active proteins, especially outer membrane -type cytochromes (OMCs), play a pivotal role in the EET process. Recent (meta)genomic analyses have revealed that diverse microorganisms that have not been demonstrated to have EET ability also harbor OMC-like proteins, indicating that EET via OMCs could be more widely preserved in microorganisms than originally thought. A methanotrophic bacterium (Bath) was reported to harbor multiple OMC genes whose expression is elevated by Cu starvation. However, the physiological role of these genes is unknown. Therefore, in this study, we explored whether (Bath) displays EET abilities via OMCs. In electrochemical analysis, (Bath) generated anodic current only when electron donors such as formate were available, and could reduce insoluble iron oxides in the presence of electron donor compounds. Furthermore, the current-generating and iron-reducing activities of (Bath) cells that were cultured in a Cu-deficient medium, which promotes high levels of OMC expression, were higher than those cultured in a Cu-supplemented medium. Anodic current production by the Cu-deficient cells was significantly suppressed by disruption of MCA0421, a highly expressed OMC gene, and by treatment with carbon monoxide (CO) gas (an inhibitor of -type cytochromes). Our results provide evidence of EET in (Bath) and demonstrate the pivotal role of OMCs in this process. This study raises the possibility that EET to solid compounds is a novel survival strategy of methanotrophic bacteria.
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http://dx.doi.org/10.3389/fmicb.2018.02905DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6281684PMC
November 2018

Hard and soft tissue responses to implant made of three different materials with microgrooved collar in a dog model.

Dent Mater J 2018 Nov 12;37(6):964-972. Epub 2018 Jul 12.

Department of Histology, The Nippon Dental University School of Life Dentistry at Niigata.

The objective of the present study was to assess hard and soft tissue around dental implants made of three different materials with microgrooves on the collar surface. Microgrooved implants were inserted in the mandibles of five male beagles. Implants were made of three kinds of material; titanium (Ti), yttria-stabilized tetragonal zirconia polycrystals (Y-TZP) and ceria partially stabilized zirconia/alumina nanocomposite (Ce-TZP/AlO). The animals were euthanatized at three months after implantation, and harvested tissue was analyzed by means of histology. All kinds of implant were osseointegrated, and there were no significant differences in any histomorphometric parameters among the three groups of microgrooved implants made of different materials. Within the limitations of this study, implants with microgrooves integrated into the surrounding bone tissue, without statistically significant differences among the three tested materials, Ti, Y-TZP, and Ce-TZP/AlO.
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http://dx.doi.org/10.4012/dmj.2017-197DOI Listing
November 2018

Loss of natural abutment teeth with cast copings retaining overdentures: a systematic review and meta-analysis.

J Prosthodont Res 2018 Oct 8;62(4):407-415. Epub 2018 Jun 8.

Division of Gerodontology, University of Bern, Bern, Switzerland; Division of Gerodontology and Removable Prosthodontics, University of Geneva, Geneva, Switzerland. Electronic address:

Purpose: To analyze the available evidence in the English, German and Japanese literature on the survival and complications of natural teeth with cast copings used to retain overdentures (ROD).

Study Selection: A systematic search strategy was conducted using MeSH terms and pre-defined criteria. Two groups of researchers searched Pubmed, CENTRAL, Embase (English, German), Ichushi-web (Japanese) as well as hand searching. Data were extracted independently by the two groups. The estimated frequency of abutment tooth loss was calculated from data on the number of lost teeth and exposure time. A meta-analysis was conducted to estimate the annual frequency of abutment tooth loss across all included studies.

Results: A total of 4791 eligible studies from PubMed, Embase, and CENTRAL. An additional 316 articles were identified from the Ichushi-Web plus another 131 articles from additional sources. From those manuscripts, 19 reported relevant outcome data that was then extracted. The pooled data included a total of 1954 abutment teeth with a combined total exposure time of 9098 years. The estimated linear rate of loss was 1.76 %/year (95 %CI 1.13; 2.72). Caries and periodontal infections were identified as the most common reasons for abutment tooth loss.

Conclusions: Natural tooth retained overdentures often constitute the last resort before edentulism and might aid in this transition, especially in very old patients with reduced adaptive capacities. Given correct design, preparation and aftercare, RODs with cast copings, still are a valid treatment option in partially edentulous patients.
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http://dx.doi.org/10.1016/j.jpor.2018.05.002DOI Listing
October 2018

Enhancement of methanogenesis by electric syntrophy with biogenic iron-sulfide minerals.

Microbiologyopen 2019 03 6;8(3):e00647. Epub 2018 Jun 6.

Bioproduction Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Sapporo, Japan.

Recent studies have shown that interspecies electron transfer between chemoheterotrophic bacteria and methanogenic archaea can be mediated by electric currents flowing through conductive iron oxides, a process termed electric syntrophy. In this study, we conducted enrichment experiments with methanogenic microbial communities from rice paddy soil in the presence of ferrihydrite and/or sulfate to determine whether electric syntrophy could be enabled by biogenic iron sulfides. Although supplementation with either ferrihydrite or sulfate alone suppressed methanogenesis, supplementation with both ferrihydrite and sulfate enhanced methanogenesis. In the presence of sulfate, ferrihydrite was transformed into black precipitates consisting mainly of poorly crystalline iron sulfides. Microbial community analysis revealed that a methanogenic archaeon and iron- and sulfate-reducing bacteria (Methanosarcina, Geobacter, and Desulfotomaculum, respectively) predominated in the enrichment culture supplemented with both ferrihydrite and sulfate. Addition of an inhibitor specific for methanogenic archaea decreased the abundance of Geobacter, but not Desulfotomaculum, indicating that Geobacter acquired energy via syntrophic interaction with methanogenic archaea. Although electron acceptor compounds such as sulfate and iron oxides have been thought to suppress methanogenesis, this study revealed that coexistence of sulfate and iron oxide can promote methanogenesis by biomineralization of (semi)conductive iron sulfides that enable methanogenesis via electric syntrophy.
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http://dx.doi.org/10.1002/mbo3.647DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6436484PMC
March 2019

Comparison of three block bone substitutes for bone regeneration: long-term observation in the beagle dog.

Odontology 2018 Oct 20;106(4):398-407. Epub 2018 Mar 20.

Department of Cranio-Maxillofacial Surgery, Inselspital, Bern University Hospital, University of Bern, Freiburugstrasse, 3010, Bern, Switzerland.

This study aimed to evaluate the impact of three types of block bone substitute material on bone formation and graft resorption in vivo. Standardized bone defects (n = 4 defects/animal) were created in the calvaria of nine dogs. Block bone substitutes made of deproteinized bovine bone mineral (DBBM), beta-tricalcium phosphate (β-TCP) and a mixture alpha-TCP and hydroxyapatite (α-TCP/HA) were inserted into the bone defects. A fourth defect was left untreated (empty). All sites were covered with a collagenous membrane. Block biopsies were harvested at 3, 6 and 12 months post-implantation and analyzed by micro-CT and histology. Biomaterial absorption was minimal and incorporation within the defect margin was good for all biomaterials. However, β-TCP demonstrated a relatively greater volume of new bone formation and less residual material volume when compared with DBBM and α-TCP/HA. Conversely, α-TCP/HA showed higher osteoconductive potential and a greater new bone area compared with the other two biomaterials. The block bone substitutes used in the present in vivo study showed advantageous in terms of maintenance of their original form in bony defect. However, the positive impact of all biomaterials on new bone formation and replacement of bone was minor even at 12 months. These findings indicate that block bone substitutes are not well suited to vertical bone augmentation. Further investigations are required to improve the insufficient new bone volume for promising clinical results.
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http://dx.doi.org/10.1007/s10266-018-0352-7DOI Listing
October 2018

Single-staged implant placement using bone ring technique with and without membrane placement: An experimental study in the Beagle dog.

Clin Oral Implants Res 2018 Mar 12;29(3):263-276. Epub 2017 Dec 12.

Department of Cranio-Maxillofacial Surgery, Inselspital, Bern University Hospital, University of Bern, Switzerland.

Aim: To evaluate the impact of a collagen membrane on bone remodeling and osseointegration of implants placed simultaneously with a bone ring technique.

Material And Methods: Standardized, vertical alveolar bone defects in the mandibles of six dogs were created. Tapered dental implants designed for two-stage subcrestal placement were inserted simultaneously with a bone ring technique. On one side of the mandible, the augmented sites were covered with a collagenous membrane. Implants with (M Group) and without membranes (NM Group) were left for an osseointegration period of 3 and 6 months, respectively. Block biopsies of the implants with surrounding bone were harvested and analyzed histologically.

Results: Implant exposure was a common finding (2/3) concomitantly with loss of healing caps. It appeared to be related to advanced bone loss around the implants. Exposure of implants was more frequent in M Group, however, without significant differences when compared to NM Group. The total bone area within the region of the bone ring was greater in the NM Group compared to the M Group. Moreover, in the region of the pristine bone of the M Group, the total bone was greater than at the corresponding NM Group sites at both observation periods. A nonparametric analysis of variance (ANOVA) revealed no significant effects of membrane placement or healing period on the total area of the bone. The total bone-to-implant contact (BIC) for the two groups was similar at each observation time point. However, BIC increased significantly at 6-month compared with 3-month observation period (p = .0088) in both groups.

Conclusions: In vertical bone augmentation applying the bone ring technique, the disruption of soft tissue was a frequent complication. Membrane placement yielded no significant advantage on the osseointegration (BIC) of implants or bone characteristics.
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http://dx.doi.org/10.1111/clr.13111DOI Listing
March 2018

A modified technique for the intraoral assessment of static occlusal contacts.

J Prosthet Dent 2018 Jun 29;119(6):909-911. Epub 2017 Nov 29.

Chairman Emeritus, Division of Fixed Prosthodontics & Biomaterials, School of Dental Medicine, Faculty of Medicine, University of Geneva, Geneva, Switzerland.

This article describes a procedure in which articulating paper is modified for the intraoral assessment of static occlusal contacts. The rectangular-shaped articulating paper is modified by creating parallel cuts at 2- to 3-mm intervals perpendicular to its long side without completely separating the paper. This modification may improve the accuracy in determining occlusal contacts and therefore facilitate an occlusal adjustment procedure.
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http://dx.doi.org/10.1016/j.prosdent.2017.10.006DOI Listing
June 2018

Clinical assessment of fractured implant abutment screws: The Bernese silicone replica technique.

J Prosthet Dent 2018 May 29;119(5):717-719. Epub 2017 Sep 29.

Fellow, Advanced Studies in Oral Implantology, Department of Reconstructive Dentistry & Gerodontology, School of Dental Medicine, University of Bern, Bern, Switzerland. Electronic address:

Fractured implant abutment screws can be retrieved with repair or rescue devices. However, whether the screw was completely retrieved or the inner implant body was damaged may be uncertain. A silicone replica technique was recently implemented in Bern and may be the most predictable method available at the moment for clinically assessing the internal implant body. This technique is straightforward and precise and may help dentists determine the internal implant condition when managing a fractured screw.
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http://dx.doi.org/10.1016/j.prosdent.2017.08.005DOI Listing
May 2018

Extracellular electron transfer in acetogenic bacteria and its application for conversion of carbon dioxide into organic compounds.

Appl Microbiol Biotechnol 2017 Aug 26;101(16):6301-6307. Epub 2017 Jul 26.

Bioproduction Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), 2-17-2-1 Tsukisamu-Higashi, Toyohira-ku, Sapporo, Hokkaido, 062-8517, Japan.

Acetogenic bacteria (i.e., acetogens) produce acetate from CO during anaerobic chemoautotrophic growth. Because acetogens fix CO with high energy efficiency, they have been investigated as biocatalysts of CO conversion into valuable chemicals. Recent studies revealed that some acetogens are capable of extracellular electron transfer (EET), which enables electron exchange between microbial cells and extracellular solid materials. Thus, acetogens are promising candidates as biocatalysts in recently developed bioelectrochemical technologies, including microbial electrosynthesis (MES), in which useful chemicals are biologically produced from CO using electricity as the energy source. In microbial photoelectrosynthesis, a variant of MES technology, the conversion of CO into organic compounds is achieved using light as the sole energy source without an external power supply. In this mini-review, we introduce the general features of bioproduction and EET of acetogens and describe recent progress and future prospects of MES technologies based on the EET capability of acetogens.
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http://dx.doi.org/10.1007/s00253-017-8421-3DOI Listing
August 2017

Progeny production in the periplasm of Thermosipho globiformans.

Extremophiles 2017 Jul 2;21(4):805-815. Epub 2017 Jun 2.

Faculty of Life and Environmental Sciences, University of Tsukuba, Tsukuba, 305-8572, Ibaraki, Japan.

Thermotogales are rod-shaped, Gram-negative, anaerobic, (hyper) thermophiles distinguished by an outer sheath-like toga, which comprises an outer membrane (OM) and an amorphous layer (AL). Thermosipho globiformans bacteria can transform into spheroids with multiple cells concurrently with AL disintegration during early growth; the cell is defined as the cytoplasmic membrane (CM) plus the entity surrounded by the CM. Spheroids eventually produce rapidly moving periplasmic 'progenies' through an unknown mechanism. Here, we used high-temperature microscopy (HTM) to directly observe spheroid generation and growth. Rod OMs abruptly inflated to form ~2 μm-diameter balloons. Concurrently, multiple globular cells emerged in the balloons, suggesting their translocation and transformation from the rod state. During spheroid growth, the cells elongated and acquired a large dish shape by possible fusion. Spheroids with dish-shaped cells further enlarged to ~12 μm in diameter. HTM and epifluorescence-microscopy results collectively indicated that the nucleoids of dish-shaped cells transformed to form a ring shape, which then distorted to form a lip shape as the spheroid enlarged. HTM showed that 'progenies' were produced in the spheroid periplasm. Transmission electron microscopy results suggested that the 'progenies' represented immature progenies lacking togas, which were acquired subsequently.
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http://dx.doi.org/10.1007/s00792-017-0944-0DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5487896PMC
July 2017
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