Seasonal Changes in Plasma Membranes and Mitochondria Isolated From Jerusalem Artichoke Tubers. Possible Relationship to Cold Hardiness

概要

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Plasma membranes and mitochondria were isolated from Jerusalem artichoke tubers during cold acclimation from September to December. The protein and lipid contents of the membranes were analyzed with reference to physiological properties of the tubers, especially cold hardiness. As cold hardiness increased from autumn to winter, the content of phospholipids and sterols on a mg protein basis increased by 20-30% in plasma membranes, but little change was observed in mitochondria. Minor changes were observed in the fatty acid composition of phospholipids either in plasma membranes or mitochondria. Membrane fluidity, assessed by fluorescent polarization of 1,6-diphenyl-1,3,5-hexatriene, was found to be relatively constant in both membranes during the season. One dimensional SDS-polyacrylamide gel electrophoresis revealed seasonal changes in proteins and glycoproteins in plasma membranes, but not in mitochondrial membranes. Plasma membrane ATPase increased in specific activity from September to December, which was more noticeable at higher assay temperatures. However, irrespective of the season, the plasma membrane ATPase had an inflection on the slope of the Arrhenius plot around 15℃. These results suggest that plasma membranes, in contrast to mitochondria, undergo several molecular changes from autumn to winter, which may be related to cold acclimation of the tubers.
日本植物生理学会の論文