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Biomedical subjects

Y Takanami

Publications and source records attributed to Y Takanami.

At least 19 recordsLinked to original sources
PubMed2004

Competition between wild-type virus and a reassortant from subgroups I and II of CMV and activation of antiviral responses in cowpea.

To investigate the interactions between RNA3 and RNA4 from subgroups I and II in mixed infections, accumulation of CMV RNA were analyzed. In the mixed inoculation assays with CMV-LE (LE, subgroup I) and a reassortant LLm consisting of RNA1 and RNA2 from LE, and RNA3 from CMV-m2 (m2, subgroup II), LE RNA3 and RNA4 could systemically spread in the plants, whereas those of m2 could not. Furthermore, accumulation of virus short RNA and a cowpea-encoded RNA-directed RNA polymerase gene (VuRdRP1) mRNA were found in the plants, suggesting that VIGS and/or distinct antiviral responses (was) were activated by infection with CMV.

Cucumovirus↗
PubMed2001

Combination of amino acids in the 3a protein and the coat protein of cucumber mosaic virus determines symptom expression and viral spread in bottle gourd.

Bottle gourd plants infected with an isolate of cucumber mosaic virus (CMV-KM) developed severe chronic mosaic symptoms (SCMS) with stunting, but two other isolates (CMV-Y and CMV-D8) did not. CMV-KM and CMV-D8 induced enlarged chlorotic spots and rapidly spread over the inoculated cotyledons, whereas CMV-Y elicited a hypersensitive response (HR) producing pin-point necrotic lesions. Reassortment analysis among the three isolates revealed that the local and systemic symptoms on the plants were regulated by RNA3. Reciprocal recombination and site-directed point mutation analyses of the three RNA3s demonstrated that a combination of genetic information encoded by the movement protein (MP) gene and the coat protein (CP) gene determines the induction of SCMS in bottle gourd. SCMS occurred when Ser51 in the MP of CMV-D8 was changed to Asn51, whereas substitution of Ser51 for Asn51 in the MP of CMV-KM eliminated its ability to induce SCMS. Furthermore, Ser129 in the CPs was shown to be responsible for induction of HR and blocking of efficient cell-to-cell and long-distance movement.

Capsid↗
PubMed2000

Vitamin E supplementation and endurance exercise: are there benefits?

It has been widely noted that vitamin E shows numerous beneficial effects through and beyond its antioxidative properties; consequently, vitamin E is expected to prevent degenerative diseases. In the field of sports medicine, many studies dealing with vitamin E have been conducted originally from the point of view of its effects on physical performance. Although some earlier studies indicated that vitamin E supplementation could improve physical performance, defects in the study design or statistical analysis were pointed out at a later time. The majority of subsequent well controlled studies have reported no significant effect on physical performance from vitamin E supplementation. Recent studies suggest that endurance exercise may promote free radical generation in the body, and vitamin E may play an important role in preventing the free radical damage associated with endurance exercise. Although there is evidence of free radical involvement in exercise-induced muscle injury, vitamin E supplementation might not be expected to prevent muscle damage caused by exercise in humans without a vitamin E deficiency. Since it is still unclear whether exercise induces lipid peroxidation in the human body, the beneficial effect of vitamin E supplementation on exercise-induced lipid peroxidation has not yet been established. However, it is proposed that as a result of exercise vitamin E may be mobilised from store tissues and redistributed in the body to prevent oxidative damage. Therefore, we are convinced that vitamin E contributes to preventing exercise-induced lipid peroxidation. It has also been indicated that strenuous endurance exercise may enhance the production of oxidised low density lipoprotein (LDL), which plays a key role in the initiation and progression of atherosclerosis. It is also suggested that this enhanced production of oxidised LDL could be reduced if a higher vitamin E status is maintained. Supplementation with 100 to 200mg of vitamin E daily can be recommended for all endurance athletes to prevent exercise-induced oxidative damage and to reap the full health benefits of exercise.

Creatine Kinase↗
PubMed2000

Vitamin E level changes in serum and red blood cells due to acute exhaustive exercise in collegiate women.

The purpose of this study was to investigate the change in vitamin E level in both serum and red blood cells (RBC) during exercise and to clarify the effect of vitamin E supplementation. Ten young sedentary female subjects received 200 mg D-alpha-tocopherol acetate daily for 1 wk after the initial exercise bout. After 1 wk of vitamin E supplementation, the same subjects repeated the same exercise. Before vitamin E supplementation, the alpha-tocopherol level in the serum (serum-alpha-tocopherol) did not change after exercise, but a significant decrease in the alpha-tocopherol level in RBC (RBC-alpha-tocopherol) was observed after exercise (p < 0.05). On the other hand, after vitamin E supplementation, the serum-alpha-tocopherol level decreased significantly after exercise (p < 0.05), while the RBC-alpha-tocopherol level was maintained after exercise. Furthermore, a negative correlation between the changes in serum- and RBC-alpha-tocopherol levels was observed only after vitamin E supplementation (r = 0.667, p < 0.05). The present results suggest that as RBC suffers oxidative stress, vitamin E in RBC is consumed to protect RBC from oxidative damage during exercise. These results also suggest that when there is a sufficient amount of vitamin E in the serum, vitamin E is shifted from the serum to RBC, resulting in a steady RBC-alpha-tocopherol level and a decrease in the serum-alpha-tocopherol level under oxidative stress such as exercise.

Adult↗
PubMed1999

Dissociable and nondissociable forms of platelet-activating factor acetylhydrolase in human plasma LDL: implications for LDL oxidative susceptibility.

Platelet-activating factor acetylhydrolase (PAF-AH) is transported by lipoproteins in plasma and is thought to possess both anti-inflammatory and anti-oxidative activity. It has been reported that PAF-AH is recovered primarily in small, dense LDL and HDL following ultracentrifugal separation of lipoproteins. In the present studies, we aimed to further define the distribution of PAF-AH among lipoprotein fractions and subfractions, and to determine whether these distributions are affected by the lipoprotein isolation strategy (FPLC versus sequential ultracentrifugation) and LDL particle distribution profile. When lipoproteins were isolated by FPLC, the bulk (approximately 85%) of plasma PAF-AH activity was recovered within LDL-containing fractions, whereas with ultracentrifugation, there was a redistribution to HDL (which contained approximately 18% of the activity) and the d>1.21 g/ml fraction (which contained approximately 32%). Notably, re-ultracentrifugation of isolated LDL did not result in any further movement of PAF-AH to higher densities, suggesting the presence of dissociable and nondissociable forms of the enzyme on LDL. Differences were noted in the distribution of PAF-AH activity among LDL subfractions from subjects exhibiting the pattern A (primarily large, buoyant LDL) versus pattern B (primarily small, dense LDL) phenotype. In the latter group, there was a relative depletion of PAF-AH activity in subfractions in the intermediate to dense range (d=1.039-1.047 g/ml) with a corresponding increase in enzyme activity recovered within the d>1.21 g/ml ultracentrifugal fraction. Thus, there appears to be a greater proportion of the dissociable form of PAF-AH in pattern B subjects. In both populations, most of the nondissociable activity was recovered in a minor small, dense LDL subfraction. Based on conjugated dienes as a measure of lipid peroxidation, variations in PAF-AH activity appeared to contribute to variations in oxidative behavior among ultracentrifugally isolated LDL subfractions. The physiologic relevance of PAF-AH dissociability and the minor PAF-AH-enriched oxidation-resistant LDL subpopulation remains to be determined.

1-Alkyl-2-acetylglycerophosphocholine Esterase↗
PubMed1998

Involvement of cucumber mosaic cucumovirus RNA2 and RNA3 in viral systemic spread in radish plant.

The genetics of cucumber mosaic cucumovirus (CMV) and the pathogenicity of the virus for Raphanus sativus were analyzed using pseudorecombinants constructed from the infectious transcripts of two naturally occurring strains of cucumber mosaic cucumovirus (CMV-D8 and CMV-Y). CMV-D8, but not CMV-Y, could cause systemic infection of the plant. Viral accumulation and systemic movement in the plants was examined using immuno-tissue blot analysis, dot blot and Northern blot hybridization. Virus was equally distributed and CMV RNAs accumulated to similar levels in the inoculated cotyledons of radish irrespective of the pseudorecombinant, suggesting that there are no apparent differences in the ability of infection and viral accumulation between CMV-D8 and CMV-Y. We found, however, that both RNAs 2 and 3 of CMV-D8 are involved in determining the efficiency for the systemic infection of R. sativus. Co-operated interactions between genetic information of RNAs 2 and 3 would control the efficient translocation of virus from the inoculated leaves to the uninoculated upper leaves of radish plant.

Blotting, Northern↗
PubMed1998

Molecular mechanism of peptide-specific pheromone signaling in Enterococcus faecalis: functions of pheromone receptor TraA and pheromone-binding protein TraC encoded by plasmid pPD1.

Conjugative transfer of the Enterococcus faecalis plasmid pPD1 is activated by cPD1, one of several peptide sex pheromones secreted by plasmid-free recipient cells, and is blocked by a donor-produced peptide inhibitor, iPD1. Using a tritiated pheromone, [3H]cPD1, we investigated how pPD1-harboring donor cells receive these peptide signals. Donor cells rapidly incorporated [3H]cPD1. The cell extract but not the membrane fraction of the donor strain exhibited significant [3H]cPD1-binding activity. On the basis of these data and those of tracer studies, it was demonstrated that cPD1 was internalized, where it bound to a high-molecular-weight compound. The cell extract of a strain carrying the traA-bearing multicopy plasmid (pDLHH21) also exhibited high [3H]cPD1-binding activity. A recombinant TraA exhibited a dissociation constant of 0.49 +/- 0.08 nM against [3H]cPD1. iPD1 competitively inhibited [3H]cPD1 binding to TraA, whereas pheromones and inhibitors relating to other plasmid systems did not. These results show that TraA is a specific intracellular receptor for cPD1 and that iPD1 acts as an antagonist for TraA. A strain carrying the traC-bearing multicopy plasmid (pDLES23) exhibited significant [3H]cPD1-binding activity. A strain carrying traC-disrupted pPD1 (pAM351CM) exhibited lower [3H] cPD1-binding activity as well as lower sensitivity to cPD1 than a wild-type donor strain. Some of the other pheromones and inhibitors inhibited [3H]cPD1 binding to the traC transformant like cPD1 and iPD1 did. These results show that TraC, as an extracellular less-specific pheromone-binding protein, supports donor cells to receive cPD1.

Bacterial Outer Membrane Proteins↗
PubMed1996

Resistance against cucumber mosaic virus in plants expressing the viral replicon.

CMV RNAs 1 and 2 are considered to constitute the viral replicon. Tobacco plants were transformed with either RNA1 or RNA2 to produce plant lines V1 and V2, respectively. Plants homozygous for each of the RNAs were generated and crossed to produce V1V2 (V2V1) lines that expressed both RNA1 and RNA2. An RNase protection assay indicated that RNA1 and RNA2 multiplied in V1V2 (V2V1) plants. Surprisingly, V1V2 (V2V1) plants, unlike their parent lines, showed a remarkably high level of resistance to CMV; this resistance was more effective against RNA inoculation than against virion inoculation. Experiments using protoplasts showed that the resistance was expressed at the single cell level. All the data together suggested that the observed resistance does not fit the criteria for either 'RNA-mediated' or 'replicase-mediated' resistance.

Base Sequence↗
PubMed1995

Point mutations in the coat protein of cucumber mosaic virus affect symptom expression and virion accumulation in tobacco.

We examined the correlation of the amino acid at position 129 in the coat protein (CP) of cucumber mosaic virus (CMV) with the phenotype of the viral pathology in tobacco by using CP mutants in which several amino acid substitutions had been introduced. An exchange between Ser129 in CMV-Y, a chlorosis-inducing strain, and Pro129 of CMV-O, a green-mosaic-inducing strain, reciprocally altered the phenotypes of those virus strains on tobacco. Replacement of either Ser129 in CMV-Y or Pro129 in CMV-O with a Leu, as is found in a chlorosis-inducing strain, CMV-M, resulted in veinal necrosis. Furthermore, we created mutants that have a Phe or a Gly at position 129. Two Phe129 mutants induced necrotic lesions on the inoculated leaves, and a Gly129 mutant induced green mosaic symptoms. In inoculated protoplasts, the mutant viruses and the wild-type virus all replicated RNA well, and accumulated CP; however, infection with the Leu129 and Phe129 mutants yielded few virions. The Phe129 mutants lacked the capacity to move systemically in tobacco; by 2 weeks post-inoculation, the Phe129 mutants occasionally gave rise to revertants that elicited chlorosis, green mosaic or veinal necrosis. Sequence analysis revealed that one had reverted to the parental Y strain, and the others had additional single amino acid changes (positions 138, 144 or 147). We suggest that amino acids at specific sites affect the whole structure of the CP and affect virus assembly, virus transport and symptom expression.

Amino Acid Sequence↗
PubMed1993

Tomato necrosis and the 369 nucleotide Y satellite of cucumber mosaic virus: factors affecting satellite biological expression.

To determine which factors can affect biological expression of the Y satellite RNA of cucumber mosaic virus (CMV) in tomato, three laboratories collaboratively exchanged their natural satellite variants, the corresponding recombinant DNA clones and helper virus strains, as well as tomato varieties, on which different observations previously reported were based. The effects of these materials and the influence of temperature on symptom expression were systematically studied. The results show that in a standardized tomato bioassay at 24 degrees C, the Y satellite, when supported by either CMV-1 or CMV-Y, did not induce tomato necrosis in the Rutgers variety but elicited a slower necrotic response in the Best of All variety that was variably lethal, as compared to the faster inevitably lethal response induced by a prototype necrogenic D satellite variant in both tomato varieties. At higher temperatures (26.5 to 32 degrees C) an extremely fast-killing necrosis caused by CMV-Y itself was observed. The study demonstrates that in experiments on virus symptom modulation induced by CMV satellites, the nature of the helper virus, host plant varieties, as well as the environmental conditions should be precisely defined, and the effects of each parameter change determined separately.

Mosaic Viruses↗
PubMed1991

DNA sequence of Mirabilis antiviral protein (MAP), a ribosome-inactivating protein with an antiviral property, from mirabilis jalapa L. and its expression in Escherichia coli.

We cloned a cDNA for Mirabilis antiviral protein (MAP), a ribosome-inactivating protein (RIP), which inhibits the mechanical transmission of plant virus and the in vitro protein synthesis of both prokaryotes and eukaryotes. The cDNA consisted of 1066 nucleotides and could encode 278 amino acids. The major part of the amino acid sequence (from Ala29 to Ser278) was identical with the sequence of native MAP as determined by protein sequencing. An NH2-terminal extrapeptide (28 amino acid residues) of MAP was comparable with the signal peptides of plant proteins accumulating in the vacuole. A stable hairpin structure was predicted in the 3'-noncoding region of the cDNA. Tandem repeated sequences were found downstream from the hairpin structure. They were composed of triple complete repeats of a heptanucleotide with preceding and following hexa-nucleotide repeats. The cDNA was expressed in Escherichia coli based on the T7 expression system. The product encoded by the cDNA was confirmed to be MAP precursor by Western blotting followed by immunological analysis. The growth of the transformants was inhibited by the expression of the gene. MAP precursor also seemed to inhibit the protein synthesis of E. coli just as native MAP has been observed to do.

Amino Acid Sequence↗
PubMed1991

Functional analysis of deletion mutants of cucumber mosaic virus RNA3 using an in vitro transcription system.

Full-length DNA copies of RNAs 1, 2, and 3 of CMV Y strain (CMV-Y) were cloned downstream of modified phage T7 promoter sequences to obtain infectious RNA transcripts. The small number of extra nonviral nucleotides at the 5' ends considerably decreased the specific infectivity of the transcripts of RNAs 1 and 2 but did not affect that of the RNA3 transcripts. Using the most infective transcripts, up to 45% of tobacco protoplasts could be infected. Various cDNA mutants were constructed from the full-length RNA3 cDNA to give RNA transcripts having deletions in the coding region of the 3a protein or the coat protein. These mutants replicated in tobacco protoplasts but did not produce systemic symptoms on tobacco when inoculated together with transcripts of RNAs 1 and 2. One of the mutants having a small in-frame deletion near the N-terminal region of the coat protein produced local lesions on cowpea and local chlorotic spots on the inoculated leaves of tobacco. These results suggest that both the 3a protein and the coat protein are involved in virus transport, and that viral assembly is associated with long-distance movement of CMV.

Base Sequence↗
PubMed1991

Reciprocal phenotype alterations between two satellite RNAs of cucumber mosaic virus.

Cucumber mosaic virus Y satellite RNA (Y-satRNA) induces distinctive yellow mosaic symptoms on tobacco, whereas S19 satellite RNA (S19-satRNA) causes an attenuated green mosaic on tobacco, although they show considerable sequence identity. Biological assays of infectious chimeric satellite RNA molecules synthesized from cDNA clones of Y-satRNA and S19-satRNA using common restriction sites showed that the determinant for the induction of yellow mosaic symptoms lies in the BstXI-NheI fragment, in which 14 nucleotide differences are found between the two satellite RNAs. To define more precisely the yellow mosaic determinant(s) in this fragment, several site-directed mutants of Y-satRNA were created. The replacement of AUU, at nucleotides 191 to 193 in Y-satRNA, with GC, which mimics the S19-satRNA sequence at the corresponding site, abolished the ability of Y-satRNA to elicit a yellow mosaic. Conversely, a mutant RNA molecule derived from S19-satRNA in which GC at nucleotides 192 and 193 was changed to AUU induced the yellow mosaic symptoms. Thus, the phenotypes of two satellite RNAs on tobacco can be altered reciprocally by changing the sequences in this limited region.

Base Sequence↗
PubMed1991

Effects of combination therapy with low-dose aspirin and warfarin on platelet functions after heart valve replacement.

To evaluate the efficacy and safety of combination therapy with aspirin and warfarin for preventing the development of thromboembolism, we compared the effects of low-dose aspirin (81 mg/day) on platelet functions to those of ticlopidine (300 mg/day) in heart valve replacement patients. Experiments were performed in two groups; the first group within 1 month after operation (the unstable period) and the second group between 3 months and 3 years after operation (the stable period). At the stable period, low-dose aspirin inhibited platelet aggregation induced by ADP, collagen, or arachidonic acid, and suppressed the increase in intracellular Ca2+ concentration [( Ca2+]i) induced by thrombin significantly. On the other hand, ticlopidine inhibited platelet aggregation induced by ADP or collagen, but did not suppress arachidonic acid-induced aggregation and the thrombin-induced [Ca2+]i increase. At the unstable period, the combination therapy of low-dose aspirin plus warfarin did not prolong the bleeding time compared to ticlopidine plus warfarin. And low-dose aspirin inhibited platelet aggregation induced by ADP, collagen or epinephrine, and especially blocked arachidonic acid-induced aggregation. Ticlopidine inhibited ADP-, collagen- or U-46619-induced aggregation, but did not affect on the increase in [Ca2+]i induced by thrombin. From the results in this study, we suggest that the combination therapy with low-dose aspirin (81 mg/day) and warfarin is safe as an antithrombotic medication in heart valve replacement, and results in the inhibition of platelet functions without any side effect calling for special mention at the early unstable period after operation.

15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5↗
PubMed1989

Determination of sequence and structural requirements for pathogenicity of a cucumber mosaic virus satellite RNA (Y-satRNA).

We describe the use of biologically active cDNA clones to investigate genetic determinants of a satellite RNA that modulates symptoms normally induced by its helper virus, cucumber mosaic virus (CMV). For this purpose, we have investigated a CMV satellite RNA (Y-satRNA) that induces bright yellow symptoms on tobacco and necrosis on tomato. To determine the pathogenicity-modulating domain of Y-satRNA, several insertion and deletion mutants were created by using various restriction sites in the cDNA of Y-satRNA, and RNA transcripts derived from the clones were mixed with CMV and used to inoculate plants. Although the satellite RNA was able to tolerate small insertions (as much as 4 bases at present), small deletions were deleterious, indicating that the sequence requirements for viability of the satellite RNA are relatively inflexible. Biological activity assays of chimeric satellite RNAs between Y-satRNA and a non-necrogenic satellite RNA, T73-satRNA, suggested that only two (or at least one of two) specific bases (positions 318 and 325) in the 3' region direct the necrogenic property of Y-satRNA. Sequences involved in production of yellow symptoms were investigated by constructing chimeras between Y-sat cDNA and cDNA of a satellite RNA designated S19-satRNA. S19-satRNA has considerable homology to Y-satRNA but does not elicit yellow symptoms on tobacco. Chimeric clones were constructed by using a BstXI site that cuts within a stable secondary structure in the region between positions 100 and 200 (region Y). The results of infectivity tests with RNA transcripts suggest that formation of a secondary structure in region Y may be involved in induction of yellow symptoms as well as viability of Y-satRNA.

Base Sequence↗