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
Electron microscopic observations revealed that the tissues of poplar ( Populus deltoides Bartr. ex Marsh) apical bud cells, which were fixed by a modified procedure of potassium permanganate fixative, showed a di...Electron microscopic observations revealed that the tissues of poplar ( Populus deltoides Bartr. ex Marsh) apical bud cells, which were fixed by a modified procedure of potassium permanganate fixative, showed a distinct endomembrane organization, in particular, the structural associations of the endoplasmic reticulum (ER) with other membrane systems. The striking findings are that some ER elements were in connection with the nuclear envelopes of two adjacent cells through plasmodesmata, and many ER elements were also associated with mitochondria, plastids, Golgi bodies or the plasma membrane (PM), forming a bridge_like continuum among various endomembrane systems or between nucleus to nucleus. A great number of plasmodesmata existed between cells, indicating a perfectly integrated symplasmic structure in poplar apical bud meristem grown in a long day environment. During the short day_induced dormancy, ER contracted, leading to its disassociation between nuclei, and between the nucleus and organelles/plasmalemma in many cells. After dormancy broke and shoots growth resumed, contracted ER was no longer observed in the apical bud cells. The ER associations with other endomembrane systems and the intercellular communication channels were re_established similar to that of plants before dormancy induction. These observations suggest that ER may play an important role in linking_up between the nucleus and organelles, and between the nucleus and the nucleus (or cell_to_cell), and seemingly coordinating various physiological processes by the bridging_like associations. And the contraction of ER under short_day may result in the growth cessation and the development of dormancy in poplar.展开更多
利用西藏高原38个气象站1981-2020年逐日气象观测资料及1970-2000年30 s空间分辨率气候数据,对人体舒适度指数(ICHB)及高原人体舒适度指数(PICHB)时空变化特征进行分析。研究表明:(1)西藏高原近40 a ICHB呈显著上升趋势,整个西藏高原年I...利用西藏高原38个气象站1981-2020年逐日气象观测资料及1970-2000年30 s空间分辨率气候数据,对人体舒适度指数(ICHB)及高原人体舒适度指数(PICHB)时空变化特征进行分析。研究表明:(1)西藏高原近40 a ICHB呈显著上升趋势,整个西藏高原年ICHB升高率为0.76·(10a)-1,各气候区年ICHB升高率为(0.57~0.98)·(10a)^(-1)。季ICHB升高率在时间上表现为冬季>秋季>春季>夏季。(2)年ICHB和季ICHB的升高率在空间上表现为西部>北部>东北部>东南部>中部、南部边缘。(3)PICHB空间上表现为寒冷特不舒适、重度高原反应的区域主要分布在北部、西部及东北部的高山上;冷不舒适、重度高原反应的区域主要分布在北部、中部及南部边缘的高山上;冷不舒适、中度高原反应的区域主要分布在北部、中部和南部边缘等区域的较低海拔地区;凉较不舒适、轻度高原反应的区域主要分布在东南部和南部边缘地区;不冷不热舒适、无高原反应的区域主要分布在错那县南部和墨脱县南部。随着西藏高原近40 a和未来气候“暖湿化”的变化趋势,各地月ICHB、季ICHB、年ICHB明显提高,PICHB也发生相应的变化,均向着舒适度升高的方向发展。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Electron microscopic observations revealed that the tissues of poplar ( Populus deltoides Bartr. ex Marsh) apical bud cells, which were fixed by a modified procedure of potassium permanganate fixative, showed a distinct endomembrane organization, in particular, the structural associations of the endoplasmic reticulum (ER) with other membrane systems. The striking findings are that some ER elements were in connection with the nuclear envelopes of two adjacent cells through plasmodesmata, and many ER elements were also associated with mitochondria, plastids, Golgi bodies or the plasma membrane (PM), forming a bridge_like continuum among various endomembrane systems or between nucleus to nucleus. A great number of plasmodesmata existed between cells, indicating a perfectly integrated symplasmic structure in poplar apical bud meristem grown in a long day environment. During the short day_induced dormancy, ER contracted, leading to its disassociation between nuclei, and between the nucleus and organelles/plasmalemma in many cells. After dormancy broke and shoots growth resumed, contracted ER was no longer observed in the apical bud cells. The ER associations with other endomembrane systems and the intercellular communication channels were re_established similar to that of plants before dormancy induction. These observations suggest that ER may play an important role in linking_up between the nucleus and organelles, and between the nucleus and the nucleus (or cell_to_cell), and seemingly coordinating various physiological processes by the bridging_like associations. And the contraction of ER under short_day may result in the growth cessation and the development of dormancy in poplar.
文摘利用西藏高原38个气象站1981-2020年逐日气象观测资料及1970-2000年30 s空间分辨率气候数据,对人体舒适度指数(ICHB)及高原人体舒适度指数(PICHB)时空变化特征进行分析。研究表明:(1)西藏高原近40 a ICHB呈显著上升趋势,整个西藏高原年ICHB升高率为0.76·(10a)-1,各气候区年ICHB升高率为(0.57~0.98)·(10a)^(-1)。季ICHB升高率在时间上表现为冬季>秋季>春季>夏季。(2)年ICHB和季ICHB的升高率在空间上表现为西部>北部>东北部>东南部>中部、南部边缘。(3)PICHB空间上表现为寒冷特不舒适、重度高原反应的区域主要分布在北部、西部及东北部的高山上;冷不舒适、重度高原反应的区域主要分布在北部、中部及南部边缘的高山上;冷不舒适、中度高原反应的区域主要分布在北部、中部和南部边缘等区域的较低海拔地区;凉较不舒适、轻度高原反应的区域主要分布在东南部和南部边缘地区;不冷不热舒适、无高原反应的区域主要分布在错那县南部和墨脱县南部。随着西藏高原近40 a和未来气候“暖湿化”的变化趋势,各地月ICHB、季ICHB、年ICHB明显提高,PICHB也发生相应的变化,均向着舒适度升高的方向发展。
