A comparative study was carried out on the EM_cytochemical localization of calcium and Ca 2+ _ATPase activity in the suspension_cultured cells between the chilling_sensitive maize ( Zea mays L. cv. Black Mexica...A comparative study was carried out on the EM_cytochemical localization of calcium and Ca 2+ _ATPase activity in the suspension_cultured cells between the chilling_sensitive maize ( Zea mays L. cv. Black Mexican Sweet) and chilling_insensitive Trititrigia ( Triticum sect. Trititrigia mackey) at 4 ℃ chilling. When maize and Tyititrigia cells were cultured at 26 ℃, electron microscopic observations revealed that the electron_dense calcium antimonate deposits, an indication of the calcium localization, were localized mainly in the vacuoles, and few was found in the cytosol and nuclei. The electron_dense cerium phosphate deposits, an indication of Ca 2+ _ATPase activity, were abundantly distributed on the plasma membrane (PM). When the cells from both species were cultured at 4 ℃ for 1 and 3 h, an elevation of Ca 2+ level in the cytosol and nuclei was observed, whereas the cerium phosphate deposits on the PM showed no quantitative difference from those of the 26 ℃_cultured cells, indicating that the enzymatic activities were not altered during these chilling periods. However, there was a distinct difference in the dynamics of the Ca 2+ distribution and the PM Ca 2+ _ATPase activity between maize and Trititrigia when chilled at 4 ℃ for 12, 24 and 72 h. In maize cells, a large number of Ca 2+ deposits still existed in the cytosol and nuclei, and the PM Ca 2+ _ATPase became less and less active, and even inactive at all. In Trititrigia cells, the increased cytosolic and nuclear Ca 2+ ions decreased after 12 h chilling. By chilling up to 24 and 72 h, the intracellular Ca 2+ concentration had been restored to a similar low level as those of the warm temperature_cultured cells, while the activity of the PM Ca 2+ _ATPase maintained high. The transient cytosolic and nuclear Ca 2+ increase and the activities of PM Ca 2+ _ATPase during chilling are discussed in relation to plant cold hardiness.展开更多
The thermodynamic of drop appearance on hydrophobic vertical surface in gravitationalfield is analyzed. The mathematical model is established. The process of the generation,development, rolling drop on the vertical su...The thermodynamic of drop appearance on hydrophobic vertical surface in gravitationalfield is analyzed. The mathematical model is established. The process of the generation,development, rolling drop on the vertical surface is expounded. The mechanic criterion ofsliding or rolling of drop is given the view of dynamics.展开更多
文摘A comparative study was carried out on the EM_cytochemical localization of calcium and Ca 2+ _ATPase activity in the suspension_cultured cells between the chilling_sensitive maize ( Zea mays L. cv. Black Mexican Sweet) and chilling_insensitive Trititrigia ( Triticum sect. Trititrigia mackey) at 4 ℃ chilling. When maize and Tyititrigia cells were cultured at 26 ℃, electron microscopic observations revealed that the electron_dense calcium antimonate deposits, an indication of the calcium localization, were localized mainly in the vacuoles, and few was found in the cytosol and nuclei. The electron_dense cerium phosphate deposits, an indication of Ca 2+ _ATPase activity, were abundantly distributed on the plasma membrane (PM). When the cells from both species were cultured at 4 ℃ for 1 and 3 h, an elevation of Ca 2+ level in the cytosol and nuclei was observed, whereas the cerium phosphate deposits on the PM showed no quantitative difference from those of the 26 ℃_cultured cells, indicating that the enzymatic activities were not altered during these chilling periods. However, there was a distinct difference in the dynamics of the Ca 2+ distribution and the PM Ca 2+ _ATPase activity between maize and Trititrigia when chilled at 4 ℃ for 12, 24 and 72 h. In maize cells, a large number of Ca 2+ deposits still existed in the cytosol and nuclei, and the PM Ca 2+ _ATPase became less and less active, and even inactive at all. In Trititrigia cells, the increased cytosolic and nuclear Ca 2+ ions decreased after 12 h chilling. By chilling up to 24 and 72 h, the intracellular Ca 2+ concentration had been restored to a similar low level as those of the warm temperature_cultured cells, while the activity of the PM Ca 2+ _ATPase maintained high. The transient cytosolic and nuclear Ca 2+ increase and the activities of PM Ca 2+ _ATPase during chilling are discussed in relation to plant cold hardiness.
文摘The thermodynamic of drop appearance on hydrophobic vertical surface in gravitationalfield is analyzed. The mathematical model is established. The process of the generation,development, rolling drop on the vertical surface is expounded. The mechanic criterion ofsliding or rolling of drop is given the view of dynamics.
