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A Shimoyama

Publications and source records attributed to A Shimoyama.

16 recordsLinked to original sources
PubMed2006

Konjak mosaic virus: the complete nucleotide sequence of the genomic RNA and its comparison with other potyviruses.

Konjak mosaic virus (KoMV) belongs to the genus Potyvirus, family Potyviridae. The complete nucleotide sequence of KoMV F isolate (KoMV F) was determined. The genome is 9,544 nucleotides long excluding the 3' terminal poly A tail and encodes a typical potyviral 350-kDa polyprotein of 3,087 amino acids. Phylogenetic analysis using known potyvirus polyproteins shows that KoMV constitutes a branch with yam mosaic virus, close to another branch including Japanese yam mosaic virus, turnip mosaic virus, scallion mosaic virus and lettuce mosaic virus. The 3' terminal 1,842 nucleotides of a different isolate of KoMV, K-2, was also determined, covering the C-terminal 292 amino acids of the nuclear inclusion protein b (NIb), coat protein (CP), and the 3' untranslated region. The amino acid sequences of the KoMV F CP and the nucleotide sequences of the KoMV F 3' untranslated region showed 92.5 and 90.5% identity to the corresponding genes of K-2, 88.7-96.8 and 92.7-94.4% to those of Zantedeschia mosaic virus (ZaMV) isolates, 87.5-89.7% and 85.5-90.3% to those of Japanese hornwort mosaic virus (JHMV) isolates. These results showed that KoMV is a distinct potyvirus and that KoMV, ZaMV, and JHMV are members of the same potyvirus species. Considering that KoMV was the first of these to be described, ZaMV and JHMV may be considered isolates of KoMV.

Amorphophallus↗
PubMed2001

Symmetrical cationic triglycerides: an efficient synthesis and application to gene transfer.

Some cationic triglycerides 1Aa-1Cb which have a symmetrical structure were effectively synthesized and formulated into cationic liposomes with the co-lipid dioleoylphosphatidylethanolamine (DOPE) and/or dilauroylphosphatidylcholine (DLPC). The plasmid encoding a luciferase was delivered into CHO cells by using these cationic liposomes. Our symmetrical cationic triglycerides showed high transfection activity when DOPE was used as a co-lipid. Among the symmetrical cationic triglycerides synthesized here, 1Ab and 1Ac, which have an oleoyl group at the 1- and 3-position in the glycerol backbone and also have a relatively long linker connecting the 2-hydroxy group in glycerol with the quaternary ammonium head group, were found to be the most suitable for gene delivery into cells. The transfection activity of the symmetrical cationic triglyceride 1Ab was comparable with that of its asymmetrical congener 6 and several times higher than that of Lipofectin.

Animals↗
PubMed1999

Molecular distribution of monocarboxylic acids in Asuka carbonaceous chondrites from Antarctica.

Molecular distribution of low-molecular-weight monocarboxylic acids was studied in three CM2 Asuka carbonaceous chondrites (A-881280, A-881334 and A-881458), which were recovered from Antarctica by the 29th Japanese Antarctic Research Expedition in 1988. GC and GC/MS analyses identified more than 30 monocarboxylic acids in A-881458, including aliphatic and aromatic acids with various structural isomers. Isomeric phenolic compounds were also identified. The aliphatic carboxylic acids have straight-chain structures having 2 to 12 carbon atoms (C2 to C12), and branched-chain structures (C4 to C9). The quantities of straight-chain acids decrease logarithmically with increasing carbon number. At the same carbon number, a straight-chain isomer is always predominant compared to branched-chain isomers. All of the 14 possible C4, C5 and C6 aliphatic monocarboxylic acids (not including optical isomers) have been identified, although all the isomers were not reported in Murchison and Y-791198 meteorites. Of the 17 possible isomeric C7 acids, at least 14 isomers were tentatively identified by mass spectra (EI and CI mode). At C8 or above, peaks of branched-chain isomers become obscure, probably due to the large number of isomers and small concentrations. Branched-chain monocarboxylic acids over C6 have never been reported in Muchison. Although occurrence of aliphatic acids are similar between A-881458 and Murchison at C4, C5 and C6 acids, a major difference is that A-881458 as well as Y-791198 have straight-chain predominance among isomers in contrast to Murchison being branched-chain predominant. In the case of isomeric aromatic compounds such as toluic acids and cresols, m-toluic acid and p-cresol are more abundant among their isomers, respectively. The molecular distribution may not reflect thermodynamic equilibrium but rather a kinetically controlled process for their formation mechanism. The other two CM2 chondrites (A-881280 and A-881334) were depleted in carboxylic acids in spite of similar carbon contents. The depletion is not due to weathering on ice, because the degrees of weathering are small and similar among the three chondrites. Probably those latter two chondrites may have been subjected to aqueous alteration or metamorphism on their meteorite parent bodies.

Antarctic Regions↗
PubMed1999

Gene transfer mediated by YKS-220 cationic particles: convenient and efficient gene delivery reagent.

A monocationic lipid, YKS-220, with a symmetrical and biodegradable structure can be used as an effective gene transfer vector in a cationic particle form (not a cationic liposome form), and is obtained by diluting an ethanol solution of YKS-220 and DOPE (1:5, molar ratio) with an aqueous medium. This preparation method is more convenient than that for cationic liposomes. YKS-220 cationic particles showed a heterogeneous large mean diameter of 4.4 microm. An obvious size change was not observed when plasmid DNA was added. The transfection activity of YKS-220 cationic particles was comparable to those of YKS-220 liposomes and DOSPA liposomes (LipofectAMINE), and even higher than that of DOGS (TRNSFECTAM). Interestingly, the YKS-220 cationic particle/DNA complexes were resistant to the neutralizing effect of serum. All of these findings indicate that YKS-220 cationic particles are a convenient and efficient gene delivery reagent.

Animals↗
PubMed1999

Properties of cationic liposomes composed of cationic lipid YKS-220 having an ester linkage: adequate stability, high transfection efficiency, and low cytotoxicity.

Cationic lipid N-[3-[2-(1,3-dioleoyloxy)propoxy-carbonyl]propyl]-N,N,N-trimethyla mmonium iodide (YKS-220) having a symmetrical and biodegradable structure was employed for the preparation of cationic liposomes with dioleoylphosphatidylethanolamine (DOPE). The stability, transfection activity in several cell lines and cytotoxicity of YKS-220 cationic liposomes were studied. It was found the YKS-220 cationic liposomes were very stable and their transfection activity remained even after storage at 4 degrees C for 12 months. The transfection activity of these liposomes was assayed using CHO, COS, and HepG2 cells and found to be comparable with, or better than, that of other cationic liposomes, such as N-[1-(2,3-dioleoyloxy)propyl]-N,N,N-trimethylammonium methylsulfate (DOTAP) liposome, N-[1-(2,3-dioleyloxy)propyl]-N,N,N-trimethylammonium chloride (DOTMA) liposome (Lipofectin), and 2,3-dioleyloxy-N-[2-(sperminecarboxamido)ethyl]-N,N-dimethyl -1-propanaminium trifluoroacetate (DOSPA) liposome (LipofectAMINE). In addition, the cytotoxicity of YKS-220 cationic liposomes was far lower than that of other cationic liposomes.

Animals↗
PubMed1997

Complex organics in meteorites.

Complex macromolecular organic matter is present in carbonaceous chondrites as the most abundant organic matter and may be present in interstellar dusts and comets. With this view, our studies of the complex organic matter isolated from six CM2 chondrites, namely Yamato-74662, Yamato-791198, Yamato-793321, Yamato-86720, Belgica-7904, and Murchison are introduced and discussed in the text. The complex organic matter is acid-insoluble and organic solvent-insoluble, and therefore, it was examined by heating experiments to obtain information on its chemical constituents and characteristics. Three chondrites, Yamato-74662, Yamato-791198, and Murchison which have solvent-extractable organic compounds, such as amino acids, carboxylic acid, hydrocarbons, etc. possess thermally labile organic fraction in the complex organic matter. Organic compounds detected in the pyrolyzate of the complex organic matter number over 130 of which aromatic hydrocarbons are dominant. They appeared around 300 degrees C, and disappeared at about 600 degrees C with a maximum at 400-500 degrees C during the heating. On the other hand, the other three chondrites do not have the extractable organic compounds nor a thermally labile organic fraction. The presence or absence of the fraction in the complex organic matter likely indicates the presence or absence of the solvent-extractable organic compounds and relates to thermal history of the chondrite.

Carbon↗
PubMed1992

Inhibition of soybean lipoxygenase-1 by n-alcohols and n-alkylthiols.

A series of n-alcohols and n-alkylthiols with carbon chains from 2 to 12 were examined for the inhibition of soybean lipoxygenase-1 (L-1). The alcohol produces a competitive inhibition, the extent of which increases with an increase in the carbon number of alkyl chain up to 8. Whereas the inhibition of the alkylthiol is noncompetitive, the extent of which is almost independent from the carbon number. From the behavior of pKi dependence on the carbon number of the alcohol, the decyl group appears to be optimum to bind to L-1. The thermodynamic analysis for the inhibition based upon van 't Hoff equation indicates positive enthalpy and entropy changes for the binding of the alcohol to the enzyme and negative enthalpy and positive to negative entropy changes for that of the alkylthiol. These observations suggest that the alcohol inhibits L-1 by binding of the hydrophobic alkyl tail to the catalytic site of the enzyme by a hydrophobic interaction. The alkylthiol inhibits by binding of the nucleophilic sulfhydryl head to a polarizable region of the enzyme and the alkyl tail to a hydrophobic region of the enzyme free from the steric hindrance as an anchor.

Alcohols↗
PubMed1982

Clay and the origin of life.

Research concerning the possible role of clay in chemical evolution is reviewed. The probable importance of clays in the origin of life is assessed.

Amino Acids↗
PubMed1982

Amino acids from the late Precambrian Thule group, Greenland.

Amino acids were recovered at concentration level of 10-9 M/g from the interior of chert and dolomite of the Late Precambrian Thule Group. Examination of the stability of amino acids in chert under dry-heating conditions suggests that these amino acids have been preserved with a predominance of L-enantiomers in the precambrian chert. Enantiomer analysis of amino acids in dolomite showed a thermal effect resulting from a late precambrian igneous intrusion. This evidence indicates that the amino acids isolated from the Thule samples were chemical fossils and not recent contaminants.

Amino Acids↗
PubMed1980

Adsorption of protein and non-protein amino acids on a clay mineral: a possible role of selection in chemical evolution.

The adsorption of protein and non-protein amino acids by Na-montmorillonite was studied at pH 3, 7, and 10, in order to determine whether clays could have played a part in selection of protein over non-protein amino acids in prebiotic times. Five pairs of amino acids, containing two to six carbons, were used at a concentration equal to 100% cation exchange capacity of the clay in adsorption experiments. The following pairs of protein and non-protein amino acids were used: glycine and sarcosine, alpha-alanine and beta-alanine, alpha-aminobutyric acid and gamma-aminobutyric acid, valine and norvaline, L-isoleucine and D-alloisoleucine. No selective adsorption of protein amino acids occurred at varying hydrogen ion concentrations. The one difference observed in the adsorption of amino acids in the mixtures was a three- and four-fold greater adsorption of beta- and gamma-amino acids, respectively, than their alpha-amino acid counterparts under acidic and neutral conditions. Strong and weak adsorption of amino acids on the clay were correlated with mechanisms such as cation exchange and hydrogen bonding. The results of this research are significant to understanding the role of clay in chemical evolution because they do not support the role of preferential adsorption of protein over non-protein amino acids by clays.

Adsorption↗
PubMed1979

Amino acids in a carbonaceous chondrite from Antarctica.

A carbonaceous chondrite from the Antarctic, referred to as the Allan Hills meteorite 77306, appears to be free from terrestrial organic contamination. The presence of both protein and non-protein amino acids and an equal abundance of D- and L-enantiomers of amino acids, is testimony to the extraterrestrial nature of these compounds.

Amino Acids↗
PubMed1977

Evidence for amino acids in hydrolysates of compounds formed by ionizing radiations. I. Aqueous solutions of HCN, NH4CN, and NaCN.

Dilute, 02-free aqueous cyanides were exposed to multikilorad doses of a radioactive cobalt source. After the removal of unreacted cyanides and of volatile radiolytic products, the residue was hydrolyzed and the resulting material analyzed for amino acids. The results show the presence of five protein amino acids and five amino acids which do not occur in natural proteins. The amino acids of enantiomeric derivatives separated on an optically active column, appeared to consist of approximately equal amounts of D and L isomers. Radiation-chemical yields of amino acids were determined at various radiation doses. The results obtained support the previous findings that the free-radical initiated process is the source of oligomers which on hydrolysis release the amino acids.

Amino Acids↗
PubMed1977

Evidence of amino acids in hydrolysates of compounds formed by ionizing radiations. II. Aqueous solutions of CH3CN and C2H5CN.

It has been shown that the action of ionizing radiations on dilute, oxygen-free, aqueous solutions of acetonitrile and propionitrile leads to the formation of oligomers, which upon hydrolyses release amino acids. The presence of nine amino acids, the same as those found in irradiated aqueous cyanides, has been established. those amino acids with asymmetric carbon atoms separated by GC method, appeared to consist of nearly equal amounts of D and L isomers. Glycine is the most abundant amino acid in hydrolysates of acetonitrile, while alanine appears in the samples of propionitrile. A comparison of all amino acids, identified in hydrolysates of various cyanides and nitriles, suggests that it is the cyano group, and a free-radical initiated mechanism, that is primarily involved in these radiation-chemical changes of potential interest to prebiotic chemistry.

Acetonitriles↗
PubMed1975

Search for amino acids in Apollo returned lunar soil.

The lunar samples from Apollo flights 11 through 17 provided the students of chemical evolution with an opportunity of examining extraterrestrial materials for evidence of early prebiological chemistry in the solar system. Our search was directed to water-extractable compounds with emphasis on amino acids. Gas chromatography, ion-exchange chromatography and gas chromatography combined with mass spectrometry were used for the analysis. It is our conclusion that amino acids are not present in the lunar regolith above the background levels of our investigations.

Amino Acids↗