Hiroshi Chiura

Quantum dot-based mortalin staining as a visual assay for detection of induced senescence in cancer cells

Abstract:  Quantum dots (QDs) are fluorescent nanocrystals that are emerging as fine alternatives to the conventional organic dyes. They have several advantages including greater photostability and a wider range of excitation–emission wavelengths. By using mortalin staining as a model, we initially demonstrated that the QDs are more stable and provide better resolution in protein imaging in fixed cells. With the help of an internalizing antibody, we generated internalizing QD (i‐QD) and demonstrated its inertness to cell replication, structure, and viability. Based on the superior resolution, stability and inertness, we propose the use of QD staining of mortalin as a cell‐based visual assay to screen for senescence‐inducing drugs, proteins, and siRNAs.

A Glucomannan as an Extracellular Product of Candida utilis I. Production and Characterization of a GlucomannanII. Structure of a Glucomannan: Characterization of Oligosaccharides Obtained by Partial Hydrolysis

A wild yeast, Candida utilis ATCC 42402, was found to secrete a glucomannan together with invertase on the consumption of sugar from the medium. The glucomannan in the culture filtrate was readily separated from the invertase by DEAE-cellulose chromatography. The crude glucomannan thus obtained was fractionated on a column of DEAE-Sephadex A-25 into several types of molecular species. The fractions were characterized by their sugar and amino acid composition which showed a tendency for an increasing mannose/glucose ratio, (1.66-5.74) coincident with greater amounts of the proteinous moiety (0.6-6%). One fraction from the DEAE-Sephadex A-25 separation, which was distinct from the other fractions in its lack of glucosamine as a component, showed a high homogeneity (M.W., 7.4 × 104 Sw,20 = 6.11 S).The structure of an extracellular glucomannan produced by Candida utilis was studied. Up to 15% hydrolysis of the glucomannan with the α-mannosidase isolated from Arthrobacter GJM-1 did not alter its viscosity. Seq...