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Masanori Saito

Publications and source records attributed to Masanori Saito.

18 recordsLinked to original sources
PubMed2006

Vacuolar localization of phosphorus in hyphae of Phialocephala fortinii, a dark septate fungal root endophyte.

Phialocephala fortinii is a dark septate fungal endophyte that colonizes roots of many host species. Its effect on plant growth varies from being pathogenic to beneficial. The basic biology of this species has received little research, and thus the main objectives of this study were to determine cytological features of hyphae, including the nature of the vacuolar system, and whether polyphosphate was present in vacuoles. Both living hyphae and hyphae that had been rapidly frozen and freeze substituted before embedding were studied. A complex system of vacuoles, including a motile tubular vacuolar system, elongated vacuoles, and spherical vacuoles, was demonstrated in living hyphae by the fluorescent probe Oregon Green 488 carboxylic acid diacetate, using laser scanning confocal microscopy. The motile tubular vacuolar system was more prevalent at the hyphal tip than in more distal regions, whereas elongated vacuoles and spherical vacuoles were more abundant distal to the tip. All vacuoles contained polyphosphate as shown by labelling embedded samples with recombinant polyphosphate binding domain of Escherichia coli exopolyphosphatase, containing Xpress tag at the N-terminal end, followed by anti-Xpress antibody and a secondary antibody conjugated either to a fluorescent probe for laser scanning confocal microscopy or colloidal gold for transmission electron microscopy. The polyphosphate was dispersed in vacuoles. This was confirmed by staining embedded samples with 4',6-diamidino-2-phenylindole and viewing with UV light using epifluorescence microscopy. These cytological methods showed that the tubular vacuolar system had lower concentrations of polyphosphate than the spherical vacuoles. Lipid bodies were present around vacuoles.

Carboxylic Acids↗
PubMed2005

A water quality analysis system to evaluate the impact of agricultural activities on N outflow in river basins in Japan.

We have developed a personal-computer-based water quality analysis system for river basins. The system estimates potential N outflow by model and calculates actual N outflow from monitoring data. For the former it uses the potential load factor method to estimate annual nitrogen load from various sources and runoff potential from each area of land in a basin. For the latter it analyzes water quality monitoring data in relation to meteorological data. We used the system to analyze N outflow in basins around Lake Kasumigaura and the Yahagi River in central Honshu, Japan. The land around Lake Kasumigaura is rather flat, and about 25% is periodically flooded for rice and lotus cultivation. The land around the Yahagi River is mountainous, and much less land is flooded. In the Yahagi River basin the actual N outflow agreed closely with the potential. However, the actual N outflow in the basin around Lake Kasumigaura was much less than the potential, suggesting that a large part of the N load is denitrified in flooded soils. This further indicates that a sequence of different land uses including flooded rice fields is an important factor determining N outflow in basins in Japan. On the basis of the above analyses, we incorporated a denitrification model into the system that enables us to estimate N balance in a designated basin; this system may be helpful in the formulation of scenarios of land use and soil management for improving water quality.

Agriculture↗
PubMed2005

Generation and characterization of reduced virulence Fusarium oxysporum f. sp. lycopersici mutants through plasmid-vector insertion.

Pathogenicity-impaired mutants, B02 and H15, of Fusarium oxysporum f. sp. lycorpersici (FOL) were obtained using restriction enzyme-mediated integration. Disease severities of Fusarium wilt caused by these mutants were significantly reduced, and their disease development rates were correlated with their colonization rates in tomato vessels. Both B02 and H15 produced significantly smaller amounts of extracellular proteins as well as fusaric acid than the wild-type. Southern blot analyses suggested that B02 and H15 likely contain a single and three copies of transformation vector, respectively. These mutants may thus be useful in isolating genes involved in pathogenicity of FOL.

DNA Restriction Enzymes↗
PubMed2005

A new hypothesis on the strategy for acquisition of phosphorus in arbuscular mycorrhiza: up-regulation of secreted acid phosphatase gene in the host plant.

The mycorrhiza-responsive phosphatase of Tagetes patula in symbiosis with Glomus etunicatum was detected by electrophoresis, was purified by column chromatography, and was characterized as acid phosphatase that was secreted into rhizosphere. The N-terminal amino acid sequence was determined by a gas-phase sequencer, and a cDNA fragment of the phosphatase gene (TpPAP1) was amplified by degenerate primers designed based on the N-terminal amino acid sequence. The full-length cDNA was obtained by the rapid amplification of cDNA ends technique. The TpPAP1 was of host origin, and the cDNA was 1,843 bp long with a predicted open reading frame of polypeptide of 466 amino acids. Phylogenetic analysis revealed that the gene fell into the cluster of plant high-molecular-weight purple acid phosphatase. Expression analysis of the TpPAP1 in T. patula in symbiosis with Archaeospora leptoticha showed that the levels of transcripts increased eightfold by mycorrhizal colonization. Western blot analysis revealed that the 57-kDa protein corresponding to the mycorrhiza-responsive phosphatase increased by mycorrhizal colonization. The present study proposes a new strategy for acquisition of P in arbuscular mycorrhizal associations in which the fungal partner activates a part of the low-P adaptation system of the plant partner, phosphatase secretion, and improves the overall efficiency of P uptake.

Acid Phosphatase↗
PubMed2005

Polyphosphate dynamics in mycorrhizal roots during colonization of an arbuscular mycorrhizal fungus.

Inorganic polyphosphate (poly P) has been considered to be a translocatable form of phosphate (Pi) in arbuscular mycorrhizal fungi (AMF). Here we examined time-course changes in poly P content during the AMF colonization process. Onion (Allium cepa) plants were cultured with or without inoculation with Gigaspora margarita for 2-8 wk with periodic sampling. Poly P in the extracts, purified through gel filtration, was quantified by the reverse reaction of polyphosphate kinase. The length of poly P in mycorrhizal roots appeared to be shorter than in extraradical hyphae or in spores of the AMF, indicating that AMF depolymerize poly P before providing Pi to the host. The poly P content increased as colonization proceeded, and was highly correlated with the weight of the colonized roots. These results support the model that AMF supply Pi to the host through the poly P pool, and that the poly P content of a mycorrhizal root can be a good indicator of the Pi-supplying activity of AMF.

Mycorrhizae↗
PubMed2005

Direct labeling of polyphosphate at the ultrastructural level in Saccharomyces cerevisiae by using the affinity of the polyphosphate binding domain of Escherichia coli exopolyphosphatase.

Inorganic polyphosphate (polyP) is a linear polymer of orthophosphate and has many biological functions in prokaryotic and eukaryotic organisms. To investigate polyP localization, we developed a novel technique using the affinity of the recombinant polyphosphate binding domain (PPBD) of Escherichia coli exopolyphosphatase to polyP. An epitope-tagged PPBD was expressed and purified from E. coli. Equilibrium binding assay of PPBD revealed its high affinity for long-chain polyP and its weak affinity for short-chain polyP and nucleic acids. To directly demonstrate polyP localization in Saccharomyces cerevisiae on resin sections prepared by rapid freezing and freeze-substitution, specimens were labeled with PPBD containing an epitope tag and then the epitope tag was detected by an indirect immunocytochemical method. A goat anti-mouse immunoglobulin G antibody conjugated with Alexa 488 for laser confocal microscopy or with colloidal gold for transmission electron microscopy was used. When the S. cerevisiae was cultured in yeast extract-peptone-dextrose medium (10 mM phosphate) for 10 h, polyP was distributed in a dispersed fashion in vacuoles in successfully cryofixed cells. A few polyP signals of the labeling were sometimes observed in cytosol around vacuoles with electron microscopy. Under our experimental conditions, polyP granules were not observed. Therefore, it remains unclear whether the method can detect the granule form. The method directly demonstrated the localization of polyP at the electron microscopic level for the first time and enabled the visualization of polyP localization with much higher specificity and resolution than with other conventional methods.

Acid Anhydride Hydrolases↗
PubMed2005

Effect of combined therapy of danaparoid sodium and tranexamic acid on chronic disseminated intravascular coagulation associated with abdominal aortic aneurysm.

Chronic disseminated intravascular coagulation (DIC) is a well-known complication of aortic aneurysm. A 63-year-old man with bleeding tendency and a large palpable abdominal aortic aneurysm (AAA) was diagnosed as having fibrinolysis dominant DIC by the excessive activation of both coagulation and fibrinolysis (plasmin -alpha2 plasmin inhibitor complex concentration is usually >4 microg/ml). Although several treatments were tried, DIC could not be controlled until the patient was given combined therapy of danaparoid (1,250 U/12 h, bolus IV) and tranexamic acid (0.5 g x 3/day, oral administration). This therapy may be beneficial when control for bleeding is required without restricting the ambulatory movement of patients by continuous drip.

Anticoagulants↗
PubMed2004

Quantification of polyphosphate: different sensitivities to short-chain polyphosphate using enzymatic and colorimetric methods as revealed by ion chromatography.

Polyphosphate is ubiquitous and has a variety of biochemical functions. Among polyphosphate quantification methods, an enzymatic assay using Escherichia coli polyphosphate kinase (PPK), in which polyphosphate is converted to adenosine 5'-triphosphate and quantified by luciferase assay, is the most specific and most sensitive. However, chain-length specificity of the assay has not been analyzed in detail so far. Ion chromatography equipped with an on-line hydroxide eluent generator enabled us to analyze polyphosphate up to 50 inorganic phosphate (P(i)) residues, and we employed this method to investigate the chain-length specificity of PPK in this study. Several fractions of short-chain polyphosphate were prepared by electrophoresis, and the chain-length distribution was analyzed before and after 1-6 h PPK reaction by ion chromatography. Polyphosphates longer than 23 P(i) residues were processed by PPK completely after 1 h incubation, but complete processing of those between 11 and 22 P(i) residues required 6h incubation. Limited processing of polyphosphates of 10 P(i) residues or shorter were observed even after 6h incubation. Metachromasy of Toluidine blue O, an alternative method for polyphosphate quantification, showed broader chain-length specificity although it was not as sensitive as the enzymatic assay. Combination of these two methods would be practically applicable to analysis of polyphosphate dynamics in living organisms.

Chromatography, Ion Exchange↗
PubMed2004

Possible involvement of hyphal phosphatase in phosphate efflux from intraradical hyphae isolated from mycorrhizal roots colonized by Gigaspora margarita.

We developed a method for separating physiologically active intraradical hyphae of arbuscular mycorrhizal (AM) fungi from mycorrhizal roots, allowing the hyphae to be used for physiological and biochemical experiments. In the present study, the phosphate efflux from the intraradical hyphae in vitro was examined in relation to hyphal phosphatase activity. Onion seedlings (Allium cepa) were planted in the soil inoculated with Gigaspora margarita. Six weeks after transplanting, the intraradical hyphae were isolated from the mycorrhizal roots using plant cell-wall digestion enzymes. The hyphae were incubated briefly at 25 degrees C in a buffer solution (50 mM Tris/HCl, pH 7.4), then incubated for 2 h and gently shaken with various inhibitors. Phosphate efflux, the amount of phosphate released to the buffer, was analysed by EnzChek phosphate assay kit. Hyphal phosphatase activity was stained histochemically and the proportion of phosphatase-active arbuscules was examined for each inhibitor. Phosphate effluxes were to some degree reduced by all inhibitors used, while the phosphatase inhibitor, BeSO4, greatly reduced the efflux. The degree of inhibition in the arbuscular phosphatase by each chemical was closely correlated to the decrease in the phosphate efflux. These results suggest that hyphal phosphatase may be partially involved in the phosphate efflux process from intraradical hyphae.

Biological Transport↗
PubMed2004

An idiopathic skin eruption resembling a butterfly rash in a septic patient with disseminated intravascular coagulation following bone marrow transplantation.

A 31-year-old man who underwent chemotherapy and bone marrow transplantation to treat acute myeloblastic leukemia was admitted to our department complaining of high fever and hypotension. His physical examination revealed warm shock state, eruptions resembling that seen in systemic lupus erythematosus on his face and cyanosis in his fingers. We diagnosed septic shock and idiopathic skin eruption on his face. Following treatment with blood transfusion, anticoagulant, antibiotics, respirator and continuous arteriovenous hemofiltration and dialysis, the patient's condition gradually improved. The eruptions on his face first observed at admission progressed with a worsening of his disseminated intravascular coagulation (DIC), and subsided with an improvement in his DIC. A biopsy of the eruption was taken and pathological findings of the eruption revealed multiple micro-fibrin depositions of the dermis. The skin necrosis in purpura fulminans often begins in the distal extremities. But our patient developed this uncommon skin eruption on his face. Patients with an idiopathic skin eruption resembling a butterfly rash in a septic patient should be considered to complicate DIC as in the present case.

Adult↗
PubMed2004

Anaerobic nitrogen-fixing consortia consisting of clostridia isolated from gramineous plants.

We report here the existence of anaerobic nitrogen-fixing consortia (ANFICOs) consisting of N(2)-fixing clostridia and diverse nondiazotrophic bacteria in nonleguminous plants; we found these ANFICOs while attempting to overcome a problem with culturing nitrogen-fixing microbes from various gramineous plants. A major feature of ANFICOs is that N(2) fixation by the anaerobic clostridia is supported by the elimination of oxygen by the accompanying bacteria in the culture. In a few ANFICOs, nondiazotrophic bacteria specifically induced nitrogen fixation of the clostridia in culture. ANFICOs are widespread in wild rice species and pioneer plants, which are able to grow in unfavorable locations. These results indicate that clostridia are naturally occurring endophytes in gramineous plants and that clostridial N(2) fixation arises in association with nondiazotrophic endophytes.

Anaerobiosis↗
PubMed2003

Different distribution of morphine and morphine-6 beta-glucuronide after intracerebroventricular injection in rats.

(1) We investigated the distribution of morphine and morphine-6beta-glucuronide (M6G) in the brain and spinal cord after intracerebroventricular (i.c.v.) injection of each drug in rats. (2) The cerebrospinal fluid (CSF) concentration of M6G was 5-37 times greater than that of morphine 10, 60 and 120 min after the i.c.v. injection. The apparent elimination clearance of M6G from the CSF was 10 times lower than that of morphine. (3) The intrathecal CSF concentration of M6G measured by the microdialysis method was 29-79 times greater than that of morphine, and M6G was rapidly distributed into the intrathecal space after the i.c.v. injection. (4) M6G was detected in the cerebrum, brainstem, cerebellum and spinal cord at concentrations 2-21 times higher than morphine after the i.c.v. injection of each drug. The distribution volume of M6G in rat brain slices was three times lower than that of morphine, and close to the extracellular fluid space in the brain regions corresponding to the vicinity of the opioid receptors. (5) These brain distribution characteristics of M6G, namely, low clearance from the central nervous system, localization in the extracellular fluid and rapid distribution into the intrathecal space, may contribute to the potent analgesic effect of M6G after i.c.v. injection.

Animals↗
PubMed2003

Factors affecting the occurrence of high-frequency positive occipital sharp transients of sleep.

To elucidate possible factors affecting the incidence of high-frequency positive occipital sharp transients of sleep (H-POSTS) and to investigate whether H-POSTS are associated with any specific pathophysiological conditions, we visually inspected on consecutive routine diurnal EEGs (2705 records) using our criteria for identification of H-POSTS. H-POSTS were observed in 164 records (subject age: 7.9 to 83.2 years). The incidence of H-POSTS was lower in subjects with highly abnormal EEG findings. Female subjects had a significantly higher incidence of H-POSTS than males that could not be explained by other factors. Patients with either fainting or headache had a significantly higher incidence of H-POSTS and lower grade of EEG abnormality. The precise mechanism of the gender difference in the incidence of H-POSTS could not be determined. The occurrence of H-POSTS seemed to be associated with healthy sleep macrostructure, rather than with any specific pathophysiological phenomena.

Adolescent↗
PubMed2002

A molecular marker diagnostic of a specific isolate of an arbuscular mycorrhizal fungus, Gigaspora margarita.

To investigate the auto-ecology of a strain of Gigaspora margarita in a commercial inoculum, we found a pair of PCR primers amplifying a sequence of 235 bp diagnostic of the isolate. We designed an oligonucleotide probe based on the DNA sequence. The combination of PCR and the probing successfully detected the diagnostic sequence from both DNA preparations of single spores and colonized roots. This protocol enabled us to distinguish the isolate among several isolates from Japan, Nepal and the USA.

Fungi↗
PubMed2002

Cognitive resource model for the information-processing of task-irrelevant visual stimuli.

In order to elucidate possible factors that effect P3s to task-irrelevant visual stimuli (non-target P3s), we made a normative visual event-related potential study with button-press tasks in four different conditions in which two factors (the number of colors of non-target stimuli, and the shape of the stimuli) were manipulated without any change in task nor target/non-target ratio. The peak distributions of non-target P3s (centrally peaking) were significantly different from those of task-relevant P3s (parietally peaking) in all conditions. The amplitude of non-target P3 decreased as the variety of colors of the non-target stimuli increased. The amplitude of non-target P3 to colored solid circles was larger than that of non-target P3 to colored Stroop stimuli. Between each condition, task- relevant P3 and reaction time showed no significant difference. Both the variety of non-target stimuli and the shape of the stimuli were shown to have effects on the amplitudes of non-target P3s without any alteration in task-relevant P3s. It is suggested that the amplitude behaviors of non-target P3s partly reflect the amount of cognitive resource allocated for each different kind of task-irrelevant visual stimuli.

Adult↗
PubMed2002

Marked difference in pathophysiology between tissue factor- and lipopolysaccharide-induced disseminated intravascular coagulation models in rats.

OBJECTIVE: Tissue factor and lipopolysaccharide frequently have been used to induce disseminated intravascular coagulation in experimental animal models. Although the pathophysiology of disseminated intravascular coagulation may differ according to the agents used to induce it, these previous models have not distinguished between the use of different disseminated intravascular coagulation-inducing agents. In this study, we attempted to evaluate the characteristic features of these agents in two types of disseminated intravascular coagulation models, with special reference to selected hemostatic parameters and pathologic findings in the kidney. DESIGN: Prospective, comparative, experimental study. SETTING: Laboratory at a university hospital. SUBJECTS: Twenty-seven male Wistar rats, age 6-7 wks, weighing 160-170 g. INTERVENTIONS: Three groups of animals were studied: a control group (n = 8) receiving physiologic saline, a tissue factor-treated group (n = 11) receiving tissue factor 3.75 units/kg, and a lipopolysaccharide-treated group (n = 8) receiving lipopolysaccharide 30 mg/kg; each group sustained infusion for 4 hrs via the tail vein. MEASUREMENTS AND MAIN RESULTS: The degree of hemostatic activation in both types of experimental disseminated intravascular coagulation was identical, based on the results of thrombin-antithrombin III complex levels. Markedly elevated D-dimer concentrations were observed without organ dysfunction or fibrin deposition in the kidney on administration of tissue factor, whereas markedly elevated plasminogen activator inhibitor activity, decreased antithrombin III activity, severe organ failure, and marked fibrin deposition in the kidney were observed for lipopolysaccharide administration. CONCLUSION: Because pathophysiology differed remarkably between the tissue factor- and lipopolysaccharide-induced disseminated intravascular coagulation models in rats, we recommend that they be assessed carefully as distinct entities to determine implications of their experimental and clinical use.

Animals↗