Effect of natural and synthetic retinoids on the proliferation and differentiation of three canine melanoma cell lines

The effect of two natural retinoids and synthetic retinoids with or without retinoid synergists on the proliferation and differentiation of 3 melanoma cell lines were investigated in vitro. No retinoids showed significant growth inhibitory effect on these cell lines when used alone, however, cell differentiation and significant growth inhibition were observed when treated with a combination of retinoids and a retinoid synergist. This study may suggest that, though the cells showed low susceptibilities when retinoids were treated alone, the combination of retinoids and a retinoid synergist may be effective to control the growth of canine melanoma cell lines.     

Determination of nitrobenzene oxidation products by GC and1H-NMR spectroscopy using 5-iodovanillin as a new internal standard

The nitrobenzene oxidation method was modified to obtain more reproducible data and more structural information about lignin, not only by gas chromatography (GC) but also by proton nuclear magnetic resonance (¹H-NMR) spectroscopy for quantitative determination of the oxidation products and to simplify the procedures. The nitrobenzene oxidation mixture was directly extracted after acidification without preextraction of by-products. The direct extraction made the extractive step easy and gave reproducible data. 5-Iodovanillin was selected as a new internal standard. The reason for this selection was that 5-iodovanillin did not exist in the nitrobenzene oxidation products from any plant species and had an aldehyde group whose peak did not overlap with the other aldehyde peaks on an¹H-NMR spectrum. Thus, the use of 5-iodovanillin enabled us to quantifyp-hydroxybenzaldehyde, vanillin, and syringaldehyde in oxidation products on the basis of¹H-NMR analysis as well as GC. Furthermore, more information about the condensed structure of lignin was derived by comparing the¹H-NMR and GC analyses.Part of this work was presented at the 42nd Annual Meeting of the Lignin Symposium, Sapporo, October 1997     

Chemical structures of the condensed tannins in the fruits of Diospyros species

The structural variety of the condensed tannins (proanthocyanidins) in the fruits of 16Diospyros species are reported. Eleven species contained condensed tannins mostly consisting of a mixture of catechin (CA) and gallocatechin (GCA) repeating units; the other five species did not. The GCA content in the CA-GCA total varied from 0.3% to 84.6%. The number of esterified gallic acid per one flavan repeating unit (degree of galloylation, DG) ranged from 0.01 to 0.89. The GCA content was found to be proportional to the DG values. Thus, 16Diospyros species tested may be classified into five groups by the analytical data of their condensed tannins. It may be interesting to compare their structural characteristics with those of the condensed tannins in other fruits, leaves, woods, and barks from the viewpoint of their biosynthesis and function in the plants.Part of this paper was presented at the 46th Annual Meeting of the Japan Wood Research Society, Tokyo, April 1995     

Preparation of novel reagents 4-alkoxytrityl chlorides and their reaction with methyl Α-d-glucoside

A series of novel 4-O-alkoxytrityl chlorides (1) with different chain lengths was synthesized as a novel reagent for obtaining 6-O-alkylated cellulose with high regioselectivity via trityl groups in one reaction step without the use of any protective groups. These chlorides were reacted with methyl -d-glucoside, which was used as a model compound, to examine the reactivities toward the primary hydroxyl groups of cellulose to afford a series of 6-O-alkylated methyl -d-glucosides in high yields. The product compounds were found to have interesting solubilities and thermal properties. Thus, newly prepared trityl chloride derivatives were found to be useful regioselective derivatization reagents on the primary hydroxyl group in carbohydrates, especially in cellulose.     

Slipping magnetic reconnection in coronal loops

Magnetic reconnection of solar coronal loops is the main process that causes solar flares and possibly coronal heating. In the standard model, magnetic field lines break and reconnect instantaneously at places where the field mapping is discontinuous. However, another mode may operate where the magnetic field mapping is continuous but shows steep gradients: The field lines may slip across each other. Soft x-ray observations of fast bidirectional motions of coronal loops, observed by the Hinode spacecraft, support the existence of this slipping magnetic reconnection regime in the Sun's corona. This basic process should be considered when interpreting reconnection, both on the Sun and in laboratory-based plasma experiments.     

At5g54160 gene encodes <Emphasis Type="Italic">Arabidopsis thaliana</Emphasis> 5-hydroxyconiferaldehyde <Emphasis Type="Italic">O</Emphasis>-methyltransferase

The function of an Arabidopsis thaliana gene, At5g54160 annotated as a caffeic acid O-methyltransferase CAOMT gene was characterized. The recombinant enzyme of this gene (AtOMT1) catalyzed the O-methylation of phenylpropanoid and flavonoid substrates. The specificity constants (k _cat/K _m) for 5-hydroxyconiferaldehyde (5-HCAld) and quercetin were both 0.11 μM⁻¹·min⁻¹. On the other hand, lignins of At5g54160-knockout Arabidopsis mutants lacked syringyl units. In addition, we showed that the gene silencing also resulted in significant accumulation of caffeyl alcohol (CaAlc). These results strongly suggested that At5g54160 gene is involved in syringyl lignin synthesis for the methylation of both 5-hydroxyconiferaldehyde and 3,4-dihydroxyphenyl compound(s). Part of this work was presented at the Annual Meeting of Japan Society for Bioscience, Biotechnology, and Agrochemistry, March 24–27, 2007     

Genotypes and allele frequencies of buried SNPs in a bovine single‐nucleotide polymorphism array in Japanese Black cattle

Single nucleotide polymorphism (SNP) arrays are widely used for genetic and genomic analyses in cattle breeding; thus, data derived from SNP arrays have accumulated on a large scale nationwide. Commercial SNP arrays contain a considerable number of unassigned SNPs on the chromosome/position on the genome; these SNPs are excluded in subsequent analyses. Notably, the position‐unassigned SNPs, or “buried SNPs” include some of the markers associated with genetic disease. In this study, we identified the position of buried SNPs using the Basic Local Alignment Search Tool against the surrounding sequences and characterized the relationship between SNPs and genetic diseases in Online Mendelian Inheritance in Animals based on the genomic position. We determined the position of 285 buried SNPs on the genome and surveyed the genotype and allele frequencies of these SNPs in 5,955 individual Japanese Black cattle. Eleven SNPs associated with genetic disease, which contained five buried SNPs, were found in the population with the risk allele frequency ranging from 0.00008396 to 0.46. These results indicate that buried SNPs in the bovine SNP array can be utilized to identify associations with genetic disorders from large scale accumulated SNP genotype data in Japanese Black cattle.     

Facile synthesis of rubiadin by microwave heating

Rubiadin (4) (1,3-dihydroxy-2-methylanthraquinone), which is one of the natural dyes from the roots of Rubiaceae, was synthesized from phthalic anhydride (1) and 2,6-dihydroxytoluene (3) by two reaction steps, that is, a Friedel-Crafts reaction with AlCl₃ and a cyclization with H₂SO₄/HBO₂. Microwave heating resulted in remarkable acceleration of the reaction rate in the first reaction, and had an effect in reducing the reaction time and increasing the yield of rubiadin (4) in the second reaction.     

Chemical structural elucidation of total lignins in woods I: fractionation of the lignin in residual wood meal after extraction of milled wood lignin

Residual wood meal after extraction of milled wood lignin (WMEM) ofEucalyptus globulus was extracted with alkali and LiCl/N,N-Dimethylacetamide (DMAc). These agents dissolve mainly hemicellulose and cellulose, respectively. The extractability of WMEM in alkali solutions was influenced by the degree of swelling of the cellulose. Under good swelling conditions, considerable amounts of cellulose and lignin were extracted with the hemicellulose. Maximum extractability was about 60% of the WMEM under optimum conditions (3 M or 5 M LiOH or 3M NaOH solution). Some portion of cellulose was extracted with LiCl/DMAc at room temperature. Thus, lignin inE. globulus WMEM was divided into three fractions: hemicellulose-lignin fraction, cellulose-lignin fraction, and insoluble-lignin fraction.Part of this work was presented at the 49th annual meeting of the Japan Wood Research Society, Tokyo, April 1999; and at the 50th annual meeting of the Japan Wood Research Society, Kyoto, April 2000     

Effects of impregnation of simple phenolic and natural polycyclic compounds on physical properties of wood

The impregnation of various simple phenolic and natural polycyclic compounds into wood was investigated from the viewpoints of vibrational property and dimensional stabilizing effect. When simple phenolic compounds were impregnated, the loss tangent (tan ) in the longitudinal direction increased linearly with increasing weight gain. Meanwhile, among the natural polycyclic compounds hematoxylin decreased the tan drastically by impregnation. It was suggested that the five hydroxyl groups and the pyran ring oxygen in the hematoxylin molecule contribute to formation of the crosslinkage-type hydrogen bonds between wood components. The rigidity of hematoxylin molecules may also be important. By impregnation of about 10% catechol, resorcinol, and saligenin, a 40% level of antiswelling efficiency (ASE) was attained, although a significant dimensional stabilizing effect was not observed after impregnation of natural polycyclic compounds.Part of this work has been published as a Rapid Communication inMokuzai Gakkaishi 43(12). It was also presented at the 48th annual meeting of the Japan Wood Research Society, Shizuoka, April 1998