水平回转对水稻幼苗叶细胞的影响

对在模拟微重力装置上回转１４ 天的水稻幼苗叶细胞进行了亚显微形态、电子探针和细胞酶化学研究。发现叶细胞质膜上Ｃａ２＋ －ＡＴＰ酶活性消失，膜内钙总量上升、膜外钙总量下降，细胞骨架变得疏松，细胞壁变薄并凹凸不平。叶绿体的基粒和线粒体的内嵴亦有部分变化。其变化机制，首先是细胞质膜上Ｃａ２＋ －ＡＴＰ酶活性消失，膜上钙泵停止工作，跨膜钙浓度差减小，膜内钙浓度上升，微管、微丝聚合受阻，细胞骨架疏松，分泌泡移动失去导向，从而导致细胞壁变薄等状态

ADAPTATIVE RESPONSES OF LEAF CELLS OF RICE SEED LING TO HORIZONTAL CLINOSTATIC CONDITIONS

The authors have studied enzyme cytochemistry, electron probe and ultrastructures in leaf cells of rice seedlings treated under horizontal clinostatic conditions simulating microgravity for 14 days.After treatment, the activity of Ca 2 ATPase in the leaf cell membrane disappeared; the density of total Ca 2 in plasm increased as that density of the cytoskeleton in the leaf cells became sparse; the cell wall was irregular being either or convex in appearance; the structure of chloroplast granas and mitochondria cristae were changed.The authors have proposed the following sequence of events: firstly, the activity of Ca 2 ATPase in leaf cell membrane disappeared; then the calcium influx in the membrane ceased functioning thereby abolished the cross membrane Ca 2 gradient; this weakened the assembly of the microtubule and microfilaments, loosened the cytoskeleton, disoriented the movement of the secretory vacuoles, and lead to cell wall thinning and irregularity.