New method for synthesizing the intermediates to 5-HETE from yeast-mediated reduction products by employing Baeyer-Villiger oxidation with complete retention of enantiomeric excess

(R) and (S)-Aldehydes 2, which are intermediates for the synthesis of (5R) and (5S)-HETE, were respectively synthesized from the yeast-mediated reductive products, hydroxy ester 3 and cis-lactone 4, through Baeyer-Villiger oxidation with complete retention of enantiomeric excess.     

The mechanism of the stabilization of the hexagonal II (HII) phase in phosphatidylethanolamine membranes in the presence of low concentrations of dimethyl sulfoxide

Dimethyl sulfoxide (DMSO), a water-miscible organic solvent, has been used as a cryoprotectant for cells. It is known that DMSO stabilizes the HII phase of phosphatidylethanolamine (PE) membranes rather than the Lalpha phase, while most other water-miscible organic solvents such as acetone and ethanol destabilize the HII phase. To elucidate the mechanism for this stabilizing effect of DMSO on the HII phase, we have investigated its effects on the structures and physical properties of PE membranes. X-ray diffraction data indicated that dipalmitoleoylphosphatidylethanolamine (DPOPE) membranes in H2O at 20 degrees C were in the Lalpha phase and that an Lalpha to HII phase transition occurred at X=0.060 (mole fraction of DMSO) in water/DMSO mixtures. As the DMSO concentration increased, the basis vector length of the dioleoylphosphatidylethanolamine (DOPE)/ 16 wt% tetradecane membrane and also of the DPOPE/ 16 wt% tetradecane membrane in the HII phase decreased, suggesting that the spontaneous curvature of these membranes increased. We have also investigated the effects of DMSO on the physical properties of the PE membranes, and compared them with those of acetone. As the DMSO concentration increased, the excimer to monomer fluorescence intensities of pyrene-phosphatidylcholine in the PE membranes decreased, indicating that the membrane fluidity decreased, and also the generalized polarization value of the Laurdan fluorescent probe in the DPOPE membrane increased, indicating that the polarity of the membrane interface decreased. On the other hand, acetone had the opposite effects to DMSO. The interaction free energy between the membrane surface segments and solvent increased with an increase in DMSO concentration. It decreased the amount of solvent in the membrane interface, inducing an increase in the spontaneous curvature. This can reasonably explain the effects of DMSO on the phase stability and the physical properties of the membranes.     

Dynamic localization and function of Bni1p at the sites of directed growth in Saccharomyces cerevisiae

Formin homology (FH) proteins are implicated in cell polarization and cytokinesis through actin organization. There are two FH proteins in the yeast Saccharomyces cerevisiae, Bni1p and Bnr1p. Bni1p physically interacts with Rho family small G proteins (Rho1p and Cdc42p), actin, two actin-binding proteins (profilin and Bud6p), and a polarity protein (Spa2p). Here we analyzed the in vivo localization of Bni1p by using a time-lapse imaging system and investigated the regulatory mechanisms of Bni1p localization and function in relation to these interacting proteins. Bni1p fused with green fluorescent protein localized to the sites of cell growth throughout the cell cycle. In a small-budded cell, Bni1p moved along the bud cortex. This dynamic localization of Bni1p coincided with the apparent site of bud growth. A bni1-disrupted cell showed a defect in directed growth to the pre-bud site and to the bud tip (apical growth), causing its abnormally spherical cell shape and thick bud neck. Bni1p localization at the bud tips was absolutely dependent on Cdc42p, largely dependent on Spa2p and actin filaments, and partly dependent on Bud6p, but scarcely dependent on polarized cortical actin patches or Rho1p. These results indicate that Bni1p regulates polarized growth within the bud through its unique and dynamic pattern of localization, dependent on multiple factors, including Cdc42p, Spa2p, Bud6p, and the actin cytoskeleton.     

Bupivacaine hydrochloride induces muscle fiber necrosis and hydroxyl radical formation-dimethyl sulphoxide reduces hydroxyl radical formation

We induced acute skeletal muscle necrosis in rats using bupivacaine hydrochloride and found that both 2,5- and 2,3-dihydroxybenzoic acid significantly increased in skeletal muscle. A single administration of dimethyl sulphoxide, a free radical scavenger, significantly lowered concentrations of 2,5- and 2,3-dihydroxybenzoic acid. These results suggest that dimethyl sulphoxide is an effective hydroxyl radical scavenger and may be useful in the treatment of myopathy.     

Isolation, tissue distribution, and chromosomal localization of the human activation-induced cytidine deaminase (AID) gene

The gene encoding activation-induced cytidine deaminase (AID), a member of the cytidine deaminase family, was isolated from a murine B cell lymphoma line, CH12F3-2, induced by combined stimulation of TGF-beta, IL-4, and CD40L. We have isolated the human orthologue of mouse AID cDNA, which has an open reading frame of 198 residues containing a conserved cytidine deaminase motif. The amino acid sequence of human AID is 92% identical to that of mouse AID. RT-PCR analysis of 15 human tissues showed that AID mRNA is expressed strongly in lymph nodes and tonsils. The complete human AID gene consisting of five exons was isolated and mapped to chromosome 12p13 by fluorescence in situ hybridization.     

Synthesis of optically active olivil type of lignan from L-arabinose using threo-selective aldol condensation as a key reaction

The threo-selective aldol condensation of (3R, 4S)-3-hydroxy-5-trityloxy-4-pentanolide, which was prepared from L-arabinose, with piperonal was applied to the stereoselective synthesis of the olivil type of lignan, (2R, 3R, 4R)-4-benzyl-4-hydroxy-3-hydroxymethyl-2-(3,4-methylenedioxyphenyl)tetrahydrofuran.     

Stereoselective model synthesis of the optically active olivil type of lignan from D-xylose

The olivil type of lignan, (2S,3R,4R)-4-benzyl-4-hydroxy - 3 - hydroxymethyl - 2 - (3,4 - methylenedioxyphenyl)tetrahydrofuran, was stereoselectively synthesized from D-xylose.     

Control of microtubule dynamics by the antagonistic activities of XMAP215 and XKCM1 in Xenopus egg extracts

Microtubules are dynamic polymers that move stochastically between periods of growth and shrinkage, a property known as dynamic instability. Here, to investigate the mechanisms regulating microtubule dynamics in Xenopus egg extracts, we have cloned the complementary DNA encoding the microtubule-associated protein XMAP215 and investigated the function of the XMAP215 protein. Immunodepletion of XMAP215 indicated that it is a major microtubule-stabilizing factor in Xenopus egg extracts. During interphase, XMAP215 stabilizes microtubules primarily by opposing the activity of the destabilizing factor XKCM1, a member of the kinesin superfamily. These results indicate that microtubule dynamics in Xenopus egg extracts are regulated by a balance between a stabilizing factor, XMAP215, and a destabilizing factor, XKCM1.