Keiko Tsuchihashi

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The large-scale mouse mutagenesis with ENU has provided forward-genetic resources for functional genomics. The frozen sperm archive of ENU-mutagenized generation-1 (G1) mice could also provide a "mutant mouse library" that allows us to conduct reverse genetics in any particular target genes. We have archived frozen sperm as well as genomic DNA from 9224 G1(More)
Mutant mouse models are indispensable tools for clarifying the functions of genes and for elucidating the underlying pathogenic mechanisms of human diseases. Currently, several large-scale mutagenesis projects that employ the chemical mutagen N-ethyl-N-nitrosourea (ENU) are underway worldwide. One specific aim of our ENU mutagenesis project is to generate(More)
Dihydroceramide desaturase, which catalyzes the introduction of a double bond at the 4,5-position of the sphingosine base in a dihydroceramide, was assayed in vitro using radiolabeled D-erythro-C18-dihydroceramide (N-stearoyl sphinganine) and homogenates of fetal rat skin, and some enzymatic properties, including substrate specificity, were determined. The(More)
A novel GM3 O-acetylated at C-4 and at C-9 of N-glycolylneuraminic acid (4,9-di-O-Ac GM3), together with a second GM3 O-acetylated at O-4 of the neuraminic acid and O-6 of D-galactose (4,6'-di-O-Ac GM3) were isolated from equine erythrocytes as a mixture in approximate 1:1 ratio. These two major species were chromatographically inseparable. Their(More)
Modified galactosylceramide with a long-chain cyclic acetal at the sugar moiety, plasmalogalactosylceramide, was isolated from equine brain. To identify the isomeric stereostructure of the natural product, the plasmalo derivative was chemically synthesized from galactosylceramide through acetalization. The presence of cyclic acetal linkage, the linked(More)
A novel galactosylalkylglycerol modified with a long-chain cyclic acetal at the sugar moiety, 3-O-(4'6'-plasmalogalactosyl) 1-O-alkylglycerol, was isolated from equine brain. The presence of cyclic acetal linkage, its linked position, and the length of the acetal chain of the natural plasmalo lipid were determined by proton NMR spectroscopy and fast-atom(More)
Equine brain gangliosides were isolated and their structures were characterized, to examine whether equine brain has N-glycolyl neuraminic acid in gangliosides, since other mammals predominantly possess N-acetyl neuraminic acid in brain gangliosides, and equine erythrocytes and organs except the brain have gangliosides exclusively containing N-glycolyl(More)
A sulfatide, O-fatty-acylated 3-sulfogalactosylceramide at C6-O on galactoside, was isolated from equine brain and the chemical structure was characterized by proton NMR and MS. The O-acylation site of the acylated sulfatide was determined by the down-field shift of protons attached to a carbon having an O-acyl group in the NMR spectrum and by analysis of a(More)
Novel mono-O-acetylated GM3s, one containing 9-O-acetylN-glycolyl neuraminic acid and another containing 6′-O-acetyl galactose, were isolated as a mixture from equine erythrocytes, and the structures were characterized by one- and two-dimensional proton nuclear magnetic resonance (NMR) and fast atom bombardment-mass spectrometry (FAB-MS). The position of(More)
A novel O-acetylated GM3 containing 3-O-acetyl 4-sphingenine was isolated with one having a non-acetylated base from transplanted rat glioma tissue. The presence and position of the acetyl group were estimated by one- and two-dimensional proton nuclear magnetic resonance, and fast atom bombardment-mass spectrometries. In addition, the O-acetyl GM3 showed(More)