Document Detail

High accumulation of soluble sugars in deep supercooling Japanese white birch xylem parenchyma cells.
MedLine Citation:
PMID:  17447912     Owner:  NLM     Status:  MEDLINE    
Seasonal changes in the accumulation of soluble sugars in extracellular freezing cortical parenchyma cells and deep supercooling xylem parenchyma cells in Japanese white birch (Betula platyphylla var. japonica) were compared to identify the effects of soluble sugars on the mechanism of deep supercooling, which keeps the liquid state of water in cells under extremely low temperatures for long periods. Soluble sugars in both tissues were analyzed by high-performance liquid chromatography (HPLC), and the concentrations of sugars in cells were estimated by histological observation of occupancy rates of parenchyma cells in each tissue. Relative and equilibrium melting points of parenchyma cells were measured by differential thermal analysis and cryoscanning electron microscopy, respectively. In both xylem and cortical parenchyma cells, amounts of sucrose, raffinose and stachyose increased in winter, but amounts of fructose and glucose exhibited little change throughout the entire year. In addition, no sugars were found to be specific for either tissue. Combined results of HPLC analyses, histological observation and melting point analyses confirmed that the concentration of sugars was much higher in xylem cells than in cortical cells. It is thought that the higher concentration of soluble sugars in xylem cells may contribute to facilitation of deep supercooling in xylem cells by depressing the nucleation temperature.
Jun Kasuga; Keita Arakawa; Seizo Fujikawa
Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  The New phytologist     Volume:  174     ISSN:  0028-646X     ISO Abbreviation:  New Phytol.     Publication Date:  2007  
Date Detail:
Created Date:  2007-04-23     Completed Date:  2007-10-23     Revised Date:  2008-11-21    
Medline Journal Info:
Nlm Unique ID:  9882884     Medline TA:  New Phytol     Country:  England    
Other Details:
Languages:  eng     Pagination:  569-79     Citation Subset:  IM    
Department of Environmental Resources, Graduate School of Agriculture, Hokkaido University, Sapporo 060-8589, Japan.
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MeSH Terms
Adaptation, Physiological
Betula / chemistry,  metabolism*
Carbohydrate Metabolism*
Carbohydrates / analysis
Cold Temperature
Trees / metabolism
Xylem / cytology,  metabolism*
Reg. No./Substance:

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