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S Moriya

Publications and source records attributed to S Moriya.

At least 19 recordsLinked to original sources
PubMed2006

Intracolony variation of bacterial gut microbiota among castes and ages in the fungus-growing termite Macrotermes gilvus.

The fungus-growing termites Macrotermes cultivate the obligate ectosymbiontic fungi, Termitomyces. While their relationship has been extesively studied, little is known about the gut bacterial symbionts, which also presumably play a crucial role for the nutrition of the termite host. In this study, we investigated the bacterial gut microbiota in two colonies of Macrotermes gilvus, and compared the diversity and community structure of bacteria among nine termite morphotypes, differing in caste and/or age, using terminal restriction fragment length polymorphism (T-RFLP) and clonal analysis of 16S rRNA. The obtained molecular community profiles clustered by termite morphotype rather than by colony, and the clustering pattern was clearly more related to a difference in age than to caste. Thus, we suggest that the bacterial gut microbiota change in relation to the food of the termite, which comprises fallen leaves and the fungus nodules of Termitomyces in young workers, and leaves degraded by the fungi, in old workers. Despite these intracolony variations in bacterial gut microbiota, their T-RFLP profiles formed a distinct cluster against those of the fungus garden, adjacent soil and guts of sympatric wood-feeding termites, implying a consistency and uniqueness of gut microbiota in M. gilvus. Since many bacterial phylotypes from M. gilvus formed monophyletic clusters with those from distantly related termite species, we suggest that gut bacteria have co-evolved with the termite host and form a microbiota specific to a termite taxonomic and/or feeding group, and furthermore, to caste and age within a termite species.

Age Factors↗
PubMed2003

Essential Bacillus subtilis genes.

To estimate the minimal gene set required to sustain bacterial life in nutritious conditions, we carried out a systematic inactivation of Bacillus subtilis genes. Among approximately 4,100 genes of the organism, only 192 were shown to be indispensable by this or previous work. Another 79 genes were predicted to be essential. The vast majority of essential genes were categorized in relatively few domains of cell metabolism, with about half involved in information processing, one-fifth involved in the synthesis of cell envelope and the determination of cell shape and division, and one-tenth related to cell energetics. Only 4% of essential genes encode unknown functions. Most essential genes are present throughout a wide range of Bacteria, and almost 70% can also be found in Archaea and Eucarya. However, essential genes related to cell envelope, shape, division, and respiration tend to be lost from bacteria with small genomes. Unexpectedly, most genes involved in the Embden-Meyerhof-Parnas pathway are essential. Identification of unknown and unexpected essential genes opens research avenues to better understanding of processes that sustain bacterial life.

Bacillus subtilis↗
PubMed2001

Degradation of G(M1) and G(M2) by mammalian sialidases.

In mammalian tissues, the pathway known for the catabolism of G(M1) [Galbeta3GalNAcbeta4(Neu5Acalpha3)Galbeta4GlcCer; where Cer is ceramide] is the conversion of this ganglioside into G(M2) [GalNAcbeta4(Neu5Acalpha3)Galbeta4GlcbetaCer] by beta-galactosidase followed by the conversion of G(M2) into G(M3) (Neu5Acalpha3Galbeta4GlcbetaCer) by beta-N-acetylhexosaminidase A (Hex A). However, the question of whether or not G(M1) and G(M2) can also be respectively converted into asialo-G(M1) (Galbeta3GalNAcbeta4Galbeta4GlcCer; G(A1)) and asialo-G(M2) (GalNAcbeta4Galbeta4GlcbetaCer, G(A2)) by mammalian sialidases has not been resolved. This is due to the fact that sialidases purified from mammalian tissues always contained detergents that interfered with the in vitro hydrolysis of G(M1) and G(M2) in the presence of an activator protein. The mouse model of human type B Tay-Sachs disease created by the disruption of the Hexa gene showed no neurological abnormalities, with milder clinical symptoms than the human counterpart, and the accumulation of G(M2) in the brains of affected mice was only limited to certain regions [Sango, Yamanaka, Hoffmann, Okuda, Grinberg, Westphal, McDonald, Crawley, Sandhoff, Suzuki and Proia (1995) Nat. Genet. 11, 170-176]. These results suggest the possible presence of an alternative catabolic pathway (the G(A2) pathway) in mouse to convert G(M2) into G(A2) by sialidase. To show the existence of this pathway, we have used recombinant mammalian cytosolic sialidase and membrane-associated sialidase to study the desialylation of G(M1) and G(M2). We found that the mouse membrane-bound sialidase was able to convert G(M1) and G(M2) into their respective asialo-derivatives in the presence of human or mouse G(M2) activator protein. The cytosolic sialidase did not exhibit this activity. Our results suggest that, in vivo, the stable NeuAc of G(M1) and G(M2) may be removed by the mammalian membrane-associated sialidase in the presence of G(M2) activator protein. They also support the presence of the G(A2) pathway for the catabolism of G(M2) in mouse.

Animals↗
PubMed2001

Diversification of the microtubule system in the early stage of eukaryote evolution: elongation factor 1 alpha and alpha-tubulin protein phylogeny of termite symbiotic oxymonad and hypermastigote protists.

The symbiotic protists of the lower termite have been regarded as a model of early-branched eukaryotes because of their simple cellular systems and morphological features. However, cultivation of these symbiotic protists is very difficult. For this reason, these interesting protists have not been well characterized in terms of their molecular biology. In research on these organisms which have not yet been cultivated, we developed a method for retrieving specific genes from a small number of cells, through micromanipulation without axenic cultivation, and we obtained EF-1 alpha and alpha-tubulin genes from members of the Hypermastigida--the parabasalid protist Trichonympha agilis and the oxymonad protists Pyrsonympha grandis and Dinenympha exilis--from the termite Reticulitermes speratus gut community. Results of phylogenetic analysis of the amino acid sequences of both proteins, EF-1 alpha and alpha-tubulin, indicate that the hypermastigid, parabasalid, and oxymonad protists do not share a close common ancestor. In addition, although the EF-1 alpha phylogeny indicates that these two groups of protists branched at an early stage of eukaryotic evolution, the alpha-tubulin phylogeny indicates that these protists can be assigned to two diversified clades. As shown in a recent investigation of alpha-tubulin phylogeny, eukaryotic organisms can be divided into three classes: an animal--parabasalids clade, a plant--protists clade, and the diplomonads. In this study, we show that parabasalids, including hypermastigids, can be classified as belonging to the animal--parabasalids clade and the early-branching eukaryote oxymonads can be classified as belonging to the plant--protists clade. Our findings suggest that these protists have a cellular microtubule system that has diverged considerably, and it seems that such divergence of the microtubule system occurred in the earliest stage of eukaryotic evolution.

Animals↗
PubMed2001

Deficiency of essential GTP-binding protein ObgE in Escherichia coli inhibits chromosome partition.

GTP-binding proteins are involved in cell proliferation, development, signal transduction, protein elongation, etc. and construct the GTPase superfamily, whose structures and sequence motifs (G-1 to G-5) are highly conserved from prokaryote to eukaryote. Obg of Bacillus subtilis and Obg homologues of other bacteria belong to the GTPase superfamily and have been suggested as being essential for cell growth, development and monitoring of intracellular levels of GTP. We identified the Obg homologue in Escherichia coli, a protein previously known as YhbZ, which we have renamed ObgE. Double cross-over experiments showed that the obgE gene is essential for growth in E. coli. From characterization of the obgE temperature-sensitive mutant, we found that DNA replication was not inhibited, that the nucleoids did not partition and instead remained in the middle of cell, and that the cells elongated. Overproduction of ObgE also resulted in aberrant chromosome segregation. These data suggested that ObgE is involved directly or indirectly in E. coli chromosome partitioning. Characterization studies showed that ObgE is abundant in normal cells, partially associated with the membrane and does not associate with ribosomes such as in Obg of B. subtilis. We purified ObgE protein from a cell extract of E. coli, and the purified ObgE had GTPase activity and DNA-binding ability.

Amino Acid Sequence↗
PubMed2001

Oxymonads are closely related to the excavate taxon Trimastix.

Despite intensive study in recent years, large-scale eukaryote phylogeny remains poorly resolved. This is particularly problematic among the groups considered to be potential early branches. In many recent systematic schemes for early eukaryotic evolution, the amitochondriate protists oxymonads and Trimastix have figured prominently, having been suggested as members of many of the putative deep-branching higher taxa. However, they have never before been proposed as close relatives of each other. We amplified, cloned, and sequenced small-subunit ribosomal RNA genes from the oxymonad Pyrsonympha and from several Trimastix isolates. Rigorous phylogenetic analyses indicate that these two protist groups are sister taxa and are not clearly related to any currently established eukaryotic lineages. This surprising result has important implications for our understanding of cellular evolution and high-level eukaryotic phylogeny. Given that Trimastix contains small, electron-dense bodies strongly suspected to be derived mitochondria, this study constitutes the best evidence to date that oxymonads are not primitively amitochondriate. Instead, Trimastix and oxymonads may be useful organisms for investigations into the evolution of the secondary amitochondriate condition. All higher taxa involving either oxymonads or Trimastix may require modification or abandonment. Affected groups include four contemporary taxa given the rank of phylum (Metamonada, Loukozoa, Trichozoa, Percolozoa), and the informal excavate taxa. A new "phylum-level" taxon may be warranted for oxymonads and Trimastix.

Animals↗
PubMed2001

Autoregulation of the dnaA-dnaN operon and effects of DnaA protein levels on replication initiation in Bacillus subtilis.

In Escherichia coli, the DnaA protein level appears to play a pivotal role in determining the timing of replication initiation. To examine the effects on replication initiation in B. subtilis, we constructed a strain in which a copy of the dnaA gene was integrated at the purA locus on the chromosome under the control of an isopropyl-beta-D-thiogalactopyranoside (IPTG)-inducible promoter. However, increasing the DnaA level resulted in cell elongation and inhibition of cell growth by induction of the SOS response. Transcription of the native dnaA-dnaN operon was greatly reduced at high DnaA levels, but it was increased in a dnaA-null mutant, indicating autoregulation of the operon by DnaA. When a copy of the dnaN gene was added downstream of the additional dnaA gene at purA, the cells grew at high DnaA levels, suggesting that depletion of DnaN (beta subunit of DNA polymerase III) within the cell by repression of the native dnaA-dnaN operon at high DnaA levels was the cause of the SOS induction. Flow cytometry of the cells revealed that the cell mass at initiation of replication increased at a lower DnaA level and decreased at DnaA levels higher than those of the wild type. Proper timing of replication initiation was observed at DnaA levels nearly comparable to the wild-type level. These results suggest that if the DnaA level increases with progression of the replication cycle, it could act as a rate-limiting factor of replication initiation in B. subtilis.

Bacillus subtilis↗
PubMed2001

DnaD protein of Bacillus subtilis interacts with DnaA, the initiator protein of replication.

The yeast two-hybrid assay revealed that Bacillus subtilis DnaD, a possible component of the primosome and required for replication initiation, interacted with DnaA and DnaD itself. The mutant DnaD23 was incapable of interacting with DnaA but retained interaction with the wild-type DnaD. These results suggest that interaction between DnaD and DnaA is important for replication initiation.

Bacillus subtilis↗
PubMed2001

[Peritoneal sclerosis in children under treatment with peritoneal dialysis].

Peritoneal dialysis(PD) is an established method of dialysis for children at the end stage of renal failure. Among several problems associated with PD, peritoneal sclerosis is one of the most serious complications. We examined four children on PD who were diagnosed as having peritoneal sclerosis in 1997 and 1998. Three of these cases were switched to hemodialysis(HD) and one is now undergoing a switch from PD to HD. Although all of the four patients had a history of bacterial peritonitis, they had been maintained in a fairly good condition on PD. The mean duration of PD was 9 years(4-14 years). All cases were anuric and had been maintained on PD without any problems of peritoneal function. From these observations, we should consider peritoneal sclerosis even in patients with a good clinical condition during the long-term period of PD. We recommend serial peritoneal biopsies, at least at the time of peritoneal catheter changes, to check for peritoneal sclerosis. The patients who are diagnosed as having sclerotic thickening of the peritoneal membrane should be switched from PD to HD to prevent the occurrence of life-threatening peritoneal sclerosis.

Adolescent↗
PubMed2000

Simple PCR detection of haptoglobin gene deletion in anhaptoglobinemic patients with antihaptoglobin antibody that causes anaphylactic transfusion reactions.

Two anhaptoglobinemic patients showing anaphylactic transfusion reactions by antihaptoglobin antibody were found. Southern blot analysis indicated that 2 patients were homozygous for the deleted allele of the haptoglobin gene (Hp(del)) as reported previously. We have identified the junction region of the deletion from genomic DNA of 1 patient using cassette-mediated polymerase chain reaction (PCR). Then, the deleted region from the 5' breakpoint to the promoter region of the Hp was amplified from genomic DNA of a control individual using PCR. DNA sequence analysis of these regions indicated that the 5' breakpoint of the Hp(del) allele was located 5. 2 kilobase (kb) upstream of exon 1 of the Hp and the 3' breakpoint was positioned between 52 and 53 base pair (bp) upstream of exon 5 of the haptoglobin-related gene. There was no significant homology between the DNA sequences flanking the 5' and 3' breakpoints, except for a 2-bp (TG) identity. To examine the gene frequency, we have developed a simple PCR method to detect the gene deletion. We found 8, 16, and 17 Hp(del) alleles in 157 Koreans, 523 Japanese, and in 284 Chinese, respectively, but did not find the Hp(del) in 101 Africans or in 100 European-Africans. The incidence of individuals homozygous for the Hp(del) allele was therefore expected to be 1/4000 in Japanese, 1/1500 in Koreans, and 1/1000 in Chinese. This incidence is higher than that of IgA deficiency in Japanese. More attention should be paid on haptoglobin deficiency and antihaptoglobin antibody as the cause of transfusion-related anaphylactic reactions in Asian populations. (Blood. 2000;95:1138-1143)

5' Untranslated Regions↗
PubMed2000

Sclerosing encapsulating peritonitis in pediatric peritoneal dialysis patients.

The aim of this study was to define the incidence and characteristics of sclerosing encapsulating peritonitis (SEP) in pediatric peritoneal dialysis (PD) patients in Japan. A questionnaire was sent to all dialysis units with at least two pediatric PD patients. Among 687 patients registered, 11 cases (1.6%) of SEP were diagnosed. The mean age of patients with SEP at the start of PD was 9.7+/-3.6 years and at SEP diagnosis, 19.1+/-3.8 years. All patients had undergone PD for more than 5 years, and the mean PD duration was 9.6+/-3.3 years. SEP was diagnosed in 6.6% and 12% of patients dialyzed for >5 years and >8 years, respectively. The incidence of peritonitis among patients with SEP was not different from that among the Japanese pediatric registry. All patients had virtually no residual urine volume and 9 had impaired peritoneal ultrafiltration. Peritoneal calcification was the most-frequent radiological finding. Peritoneal biopsy was performed in 7 patients and confirmed sclerotic peritonitis in all. Ten patients transferred to hemodialysis, and only 1 patient underwent surgery. Three patients died. We recommend that patients on PD for more than 5 years who have impaired peritoneal ultrafiltration or peritoneal calcification should be carefully managed as presumptive cases of SEP.

Adolescent↗
PubMed2000

Diverse genes of cellulase homologues of glycosyl hydrolase family 45 from the symbiotic protists in the hindgut of the termite Reticulitermes speratus.

Diverse genes encoding cellulase homologues belonging to glycosyl hydrolase family 45 were identified from the symbiotic protists in the hindgut of the termite Reticulitermes speratus through the use of consensus PCR and the screening of a cDNA library. Fifteen full-length cDNA clones were isolated and sequenced, which encoded polypeptides consisting of 218-221 amino acid residues showing up to 63% identity to known family 45 cellulases. The cellulase sequences of the termite symbiotic protists were phylogenetically monophyletic, showing more than 75% amino acid identity with each other. These enzymes consist of a single catalytic domain, lacking the ancillary domains found in most microbial cellulases. By whole-cell in situ hybridization using oligonucleotide probes specific for regions conserved in some of the sequences, the origin of the genes was identified as symbiotic hypermastigote protists. The presence of diverse cellulase homologues suggests that symbiotic protists of termites may be rich reservoirs of novel cellulase sequences.

Amino Acid Sequence↗
PubMed2000

Subcellular localization of Dna-initiation proteins of Bacillus subtilis: evidence that chromosome replication begins at either edge of the nucleoids.

We examined the intracellular distribution of Bacillus subtilis Dna-initiation proteins by immunofluorescence microscopy to visualize the initiation complex of replication in vivo. DnaA was distributed throughout the cytoplasm, but both DnaB and DnaI were always detected as foci during the cell-division cycle. Interaction of DnaI with the DnaC helicase by the yeast two-hybrid assay suggests that DnaI acts as a helicase loader. The number of DnaB and DnaI foci within the cell exceeded that of oriC. Although the foci were not always co-localized with oriC, they seemed to be localized near the outer or inner edges of the nucleoids at initiation of replication. When the replication cycle was synchronized in cells using a temperature-sensitive dnaA mutant, duplication of the oriC region was observed predominantly near an edge of the nucleoid. Before initiation occurred, each one of the DnaB and DnaI foci was frequently observed near there. Furthermore, DnaX-GFP (DnaX is a component of DNA polymerase III) foci were detected near either of the edges of the nucleoids at the onset of replication. These results suggest that the replisome is recruited into oriC near either edge of the nucleoids to initiate chromosome replication in B. subtilis.

Animals↗
PubMed2000

Identification of candidate endothelial cell autoantigens in systemic lupus erythematosus using a molecular cloning strategy: a role for ribosomal P protein P0 as an endothelial cell autoantigen.

OBJECTIVE: To attempt to characterize the diversity and nature of antigens recognized by anti-endothelial cell antibodies (AECA) in patients with systemic lupus erythematosus (SLE) using a molecular cloning strategy. METHODS: AECA in sera of 15 SLE patients were measured by ELISA and Western blot analysis was used to examine the diversity of autoantigen targets in two clinically active patients. A human umbilical vein endothelial cell cDNA expression library was immunoscreened with sera from these two patients to identify their autoantigen targets. An anti-ribosomal P peptide antibody ELISA was used to assess the clinical significance of anti-ribosomal P protein antibodies in the sera of one patient. RESULTS: Significantly higher AECA levels were found in five patients with active disease and nephritis than in five patients with clinically inactive disease. Sera from two clinically active patients were found to recognize distinct spectra of autoantigens. The candidate autoantigens that were identified included (1) endothelial cell-specific plasminogen activator inhibitor; (2) the classical lupus antigen, i.e. ribosomal P protein P0; and (3) proteins never before described as putative autoantigens in SLE, including ribosomal protein L6, elongation factor 1alpha, adenyl cyclase-associated protein, DNA replication licensing factor, profilin II and the novel proteins HEAPLA 1 and HEAPLA 2 (human endothelial associated putative lupus autoantigens 1 and 2). In one patient, antibodies against ribosomal P protein P0 were predominant and levels of these antibodies correlated with total AECA levels, anti-DNA antibody titres, overall clinical score and renal disease in a longitudinal study. CONCLUSIONS: A panel of candidate endothelial autoantigens in SLE, which includes previously described autoantigens and novel targets, has been identified by a molecular cloning strategy. This novel molecular approach could also be applied to the identification of autoantigens in other autoimmune vascular diseases.

Autoantibodies↗
PubMed2000

[Henoch-Schönlein purpura nephritis (HSPN) in children: comparison of the incidence and severity between two 12-year groups].

From 1971 to 1982, we treated 286 patients of HSP in Kitasato University Hospital. In these 286 patients, 137 developed purpura nephritis (47.9%). During the second 12-year period (from 1985 to 1996), we treated 34 HSPN patients among 189 HSP patients (18.0%). The clinico-pathological evaluations and comparisons in 30 cases from 1971 to 1982 and in 11 cases from 1985 to 1996 were performed, using the ISKDC grading. The numbers of patients of HSP and the incidence of HSPN both decreased in the more recent 12-year group. Furthermore, the severity of the renal histopathological findings decreased in the more recent group as well.

Adolescent↗
PubMed2000

Glutathione depletion enhances the formation of superoxide anion released into hepatic sinusoids after lipopolysaccharide challenge.

BACKGROUND: We examined the effects of glutathione depletion on the level of superoxide anion released into hepatic sinusoids after lipopolysaccharide challenge. METHODS: Rats were given 1 mg/kg of maleic acid diethyl ester to deplete glutathione in vivo and then 0.5 mg/kg body weight of lipopolysaccharide. RESULTS: This treatment significantly depleted serum reduced glutathione (32.7 +/- 1.7 vs. 23.0 +/- 3.2 mM, p = 0.002). However, it did not affect the serum oxidized glutathione concentration (2.88 +/- 0.56 vs. 3.10 +/- 0.78 mM, not significant). The lipopolysaccharide challenge caused significant superoxide anion formation as compared with controls (0.12 +/- 0.04 vs. 0.22 +/- 0.05 o.d., p < 0.001), and it was enhanced significantly by glutathione depletion (0.28 +/- 0.04 o.d., p < 0.05). There were no significant differences in levels of lipopolysaccharide (2142 +/- 452 vs. 2503 +/- 612 pg/ml) and tumor necrosis factor alpha (277 +/- 186 vs. 252 +/- 88 pg/ml) after the lipopolysaccharide challenge between the glutathione-depleted and nondepleted rats. Moreover, the purine nucleoside phosphorylase/glutamic-pyruvic transaminase ratio in liver perfusates, a marker of damage to endothelial cells in hepatic sinusoids, was significantly higher in the glutathione-depleted rats than in the nondepleted rats. CONCLUSIONS: The reduced form of glutathione can decrease levels of the superoxide anion released into hepatic sinusoids and can decrease subsequent damage to endothelial cells in these sinusoids caused by lipopolysaccharide; that is, it can reduce lipopolysaccharide-induced liver injury.

Animals↗