New sesquiterpene lactone glucosides from the roots of Ferula varia

Five new eudesmane- (1–5), two new guaiane- (6 and 7) and one new germacrane-type (8) sesquiterpene lactone glucosides were isolated from the H₂O-soluble fraction of the roots of Ferula varia. Their structures were elucidated by extensive spectroscopic analyses. The absolute configuration of 1 was determined by modified Mosher's method.     

A noninvasive method for extracting bivalve DNA from the water-filled mantle cavity

Genetic studies play a great role for determining the biology of bivalves, particularly those covering population genetics, phylogeny, breeding, stock management, and conservation. However, DNA sampling methods that require removal of bivalves from the water and/or opening of their shells often cause stress and damage to bivalves, which can be lethal. The invasiveness of DNA sampling has made it difficult to conduct genetic studies in threatened species, rare species, and/or breeding lineages. In the present study, we developed a non-invasive method for bivalve DNA sampling using the water-filled mantle cavity (WMC). Our method can extract DNA from a small WMC sample (about 100 µl), collected using a fine needle and syringe without opening the shell. We demonstrated that the WMC sample contains intact mitochondrial and nuclear DNA. DNA contamination from other organisms, such as adjacent bivalve individuals, did not affect the resulting PCR and DNA sequencing analyses. Finally, the individuals from whom WMC was collected remained alive for more than 2 months after the experiments. This non-invasive method will be of great assistance in investigating the genetics of bivalves.

     

The coreceptor CD2 uses plasma membrane microdomains to transduce signals in T cells

The interaction between a T cell and an antigen-presenting cell (APC) can trigger a signaling response that leads to T cell activation. Prior studies have shown that ligation of the T cell receptor (TCR) triggers a signaling cascade that proceeds through the coalescence of TCR and various signaling molecules (e.g., the kinase Lck and adaptor protein LAT [linker for T cell activation]) into microdomains on the plasma membrane. In this study, we investigated another ligand–receptor interaction (CD58–CD2) that facilities T cell activation using a model system consisting of Jurkat T cells interacting with a planar lipid bilayer that mimics an APC. We show that the binding of CD58 to CD2, in the absence of TCR activation, also induces signaling through the actin-dependent coalescence of signaling molecules (including TCR-ζ chain, Lck, and LAT) into microdomains. When simultaneously activated, TCR and CD2 initially colocalize in small microdomains but then partition into separate zones; this spatial segregation may enable the two receptors to enhance signaling synergistically. Our results show that two structurally distinct receptors both induce a rapid spatial reorganization of molecules in the plasma membrane, suggesting a model for how local increases in the concentration of signaling molecules can trigger T cell signaling.     

Isotopic Determination and Optimum Reaction Conditions of Pantothenic Acid Synthetase

When yeast protoplasts that were producing repressible acid phosphatase (r-APase) were treated with tunicamycin (TM), three specific proteins of 59k, 57k, and 55k daltons were accumulated in the membrane fraction in addition to the usual membrane proteins and these proteins were not detected in the secreted fraction. These proteins were immunoprecipitated with anti r-APase antiserum. Their molecular sizes were almost the same as those endo-H treated r-APase. Therefore these proteins were considered to be nonglycosylated forms of r-APase proteins. These results proved that nonglycosylated forms of r-APase produced by TM-treatment were not secreted by yeast protoplasts.     

Synthesis and characterization of novel Cu(II)-bipyridine complexes having functional groups and their application toward molecular recognition

Two kinds of Cu(II) complexes having 2,2′-bipyridine derivatives with two 1-naphthoylamide groups or two ethyl dimethylmalonylamide moieties at 6 and 6′ positions as ligands were prepared and characterized by X-ray crystallography and spectroscopic methods. Those ligands bound to the Cu(II) centers in a tetradentate fashion including two amide oxygen atoms in the equatorial planes. Those complexes were found to recognize carboxylic acids as guest molecules by coordination and additional non-covalent interactions, including intramolecular π-π interactions or hydrogen bonding.     

Mechanism of photoisomerization of optically pure trans-2,3-diphenylcyclopropane-1-carboxylic acid derivatives.

The photochemistry of optically pure isomers of alpha-methylbenzylamide of trans-2,3-diphenylcyclopropane-1-carboxylic acid has been examined in isotropic solution and within zeolites. The results suggest that these isomerize through cleavage of C2-C3 bond. The direct excitation in solution leads to non-equilibrating 1,3-singlet diradical intermediates whereas triplet sensitization results in equilibrating 1,3-triplet diradical intermediates. The direct excitation within NaY zeolite seems to result in equilibrating zwitterionic intermediates. Studies on the optically pure trans isomers allow one to understand the mechanism of chiral induction during the photoisomerization of mesocis-2,3-diphenylcyclopropane-1-carboxylic acid. The current study has clarified the nature of the excited states involved during the classic (R)-N-acetyl-1-naphthylethylamine sensitized isomerization of 1,2-diphenylcyclopropane.     

“Nojirimycin” as a Potent Inhibitor of Glucosidase

Glucose-6-phosphate dehydrogenase in a yeast, Hansenula mrakii IFO 0895 is induced when the cells are cultured in a medium containing lipid hydroperoxide. The enzyme was purified from H. mrakii to the homogeneous state on polyacrylamide gel electrophoresis. The molecular weight of the purified enzyme was estimated to be approximately 52kDa by SDS-PAGE and 130 kDa by Sephadex G-150column chromatography, respectively. The enzyme was specific to glucose-6-phosphate and NADP⁺, and K_mvalues for glucose-6-phosphate and NADP⁺ were 293µM and 24.1 µM, respectively. The enzyme activity was inhibited by diethylpyrocarbonate and 2, 4, 6-trinitrobenzene sulfonate, and by metal ions such as Zn^{2 +}, Cd^{2 +}, Cu^{2 +}, and Al^{3 +} . tert-Butyl hydroperoxide, a kind of lipid hydroperoxide, slightly(approximately 20%) increased the enzyme activity.     

Metabolic stability and inhibitory effect of O-methylated theaflavins on H2O2-induced oxidative damage in human HepG2 cells

Seven new O-methylated theaflavins (TFs) were synthesized by using O-methyltransferase from an edible mushroom. Using TFs and O-methylated TFs, metabolic stability in pooled human liver S9 fractions and inhibitory effect on H₂O₂-induced oxidative damage in human HepG2 cells were investigated. In O-methylation of theaflavin 3′-O-gallate (TF3′G), metabolic stability was potentiated by an increase in the number of introduced methyl groups. O-methylation of TF3,3′G did not affect metabolic stability, which was likely because of a remaining 3-O-galloyl group. The inhibitory effect on oxidative damage was assessed by measuring the viability of H₂O₂-damaged HepG2 cells treated with TFs and O-methylated TFs. TF3,3′G and O-methylated TFs increased cell viabilities significantly compared with DMSO, which was the compound vehicle (p?<?0.05), and improved to approximately 100%. Only TF3′G did not significantly increase cell viability. It was suggested that the inhibitory effect on H₂O₂-induced oxidative damage was potentiated by O-methylation or O-galloylation of TFs.