Ray Wu, 79; developed rice strains with potential to increase world supply

Cornell University

'HE MADE ENORMOUS CONTRIBUTIONS': The strains of rice that Ray Wu produced with his research are now being cross-bred with commercial rice varieties in several countries in order to introduce their desirable traits into widely used strains.

Nature Materials 5, 632 - 635 (2006)
doi:10.1038/nmat1681

Organization and mobility of water in amorphous and crystalline trehalose

Duncan Kilburn, Sam Townrow, Vincent Meunier, Robert Richardson, Ashraf Alam and Job Ubbink

The disaccharide trehalose is accumulated by microorganisms, such as yeasts, and multicellular organisms, such as tardigrades, when conditions of extreme drought occur. In this way these organisms can withstand dehydration through the formation of an intracellular carbohydrate glass, which, with its high viscosity and hydrogen-bonding interactions, stabilizes and protects the integrity of complex biological structures and molecules. This property of trehalose can also be harnessed in the stabilization of liposomes, proteins and in the preservation of red blood cells, but the underlying mechanism of bioprotection is not yet fully understood. Here we use positron annihilation lifetime spectroscopy to probe the free volume of trehalose matrices; specifically, we develop a molecular picture of the organization and mobility of water in both amorphous and crystalline states. Whereas in amorphous matrices, water increases the average intermolecular hole size, in the crystalline dihydrate it is organized as a confined one-dimensional fluid in channels of fixed diameter that allow activated diffusion of water in and out of the crystallites. We present direct real-time evidence of water molecules unloading reversibly from these channels, thereby acting as both a sink and a source of water in low-moisture systems. We postulate that this behaviour may provide the overall stability required to keep organisms viable through dehydration conditions.

1.       H.H. Wills Physics Laboratory, University of Bristol, Tyndall Avenue, Bristol BS8 1TL, UK

2.       Nestlé Research Center, Vers-chez-les-Blanc, CH-1000 Lausanne 26, Switzerland

Crystallization inhibition of an amorphous sucrose system using raffinose*
K.M. Leinen and T.P. Labuza†
Department of Food Science and Nutrition, University of Minnesota, St. Paul, MN 55108, USA
†E-mail:tplabuza@umn.edu

Abstract

The shelf life of pure amorphous sucrose systems, such as cotton candy, can be very short. Previous studies have shown that amorphous sucrose systems held above the glass transition temperature will collapse and crystallize. One study, however, showed that adding a small percent of another type of sugar, such as trehalose, to sucrose can extend the shelf life of the amorphous system by slowing crystallization. This study explores the hypothesis that raffinose increases the stability of an amorphous sucrose system. Cotton candy at 5 wt% raffinose and 95 wt% sucrose was made and stored at room temperature and three different relative humidities (%RH) 11%RH, 33%RH, and 43%RH. XRD patterns, and glass transition temperatures were obtained to determine the stability as a function of %RH. The data collected showed that raffinose slows sucrose crystallization in a low moisture amorphous state above the glass transition temperature and therefore improves the stability of amorphous sucrose systems.

Source

A bifunctional TPS-TPP enzyme from yeast confers tolerance to multiple and extreme abiotic-stress conditions in transgenic Arabidopsis

Miranda, José * ; Avonce, Nelson; Suárez, Ramón; Thevelein, Johan; Van Dijck, Patrick; Iturriaga, Gabriel

Improving stress tolerance is a major goal for agriculture. Trehalose is a key molecule involved in drought tolerance in anhydrobiotic organisms. Here we describe the construction of a chimeric translational fusion of yeast trehalose-6-phosphate synthase and trehalose-6-phosphate phosphatase. This construct was overexpressed in yeast cells displaying both TPS and TPP enzyme activities and trehalose biosynthesis capacity. In Arabidopsis thaliana, the gene fusion was overexpressed using either the 35S promoter or the stress-regulated rd29A promoter. Transgene insertion in the genome was checked by PCR and transcript expression by RT-PCR. Several independent homozygous lines were selected in the presence of kanamycin and further analyzed.