Fisher D B
Department of Botany, University of Georgia, Athens, Georgia 30602.
Plant Physiol. 1979 Sep;64(3):481-3. doi: 10.1104/pp.64.3.481.
Intracellular sucrose compartmentation in the palisade parenchyma of Vicia faba L. leaflets was investigated by comparing the specific radioactivity of photosynthetically labeled [(14)C]sucrose in samples enriched in vacuole to that in samples enriched in cytoplasm. Brief centrifugation of leaflet punches was used to sediment most of the palisade parenchyma cytoplasm in the adaxial ends of the cells. The punches were quick-frozen, freeze-substituted, and embedded in methacrylate. Samples enriched in cytoplasm or in vacuoles were obtained from paradermal sections. After pulse-labeling, the sucrose specific radioactivity in vacuole-enriched samples was fairly constant. Sucrose specific radioactivity in cytoplasm-enriched samples was about 2.5 times that in vacuole-enriched samples initially and declined thereafter. Earlier interpretation of intracellular sucrose compartmentation (Plant Physiol 1975 55: 704-711) had predicted larger specific activity differences (up to 20 times) between the cytoplasm and vacuole. The difference between the actual and predicted behavior is ascribed to the observed extent of cross-contamination in samples and, more importantly, to the confinement of sucrose to extrachloroplastic regions of the cytoplasm.
通过比较富含液泡的样品与富含细胞质的样品中光合标记的[(14)C]蔗糖的比放射性，研究了蚕豆小叶栅栏薄壁组织中的细胞内蔗糖区室化。对小叶切片进行短暂离心，以使细胞近轴端的大部分栅栏薄壁组织细胞质沉淀。将切片快速冷冻、冷冻置换并包埋在甲基丙烯酸酯中。从副表皮切片中获取富含细胞质或液泡的样品。脉冲标记后，富含液泡的样品中蔗糖比放射性相当恒定。富含细胞质的样品中蔗糖比放射性最初约为富含液泡样品的2.5倍，此后下降。早期对细胞内蔗糖区室化的解释（《植物生理学》1975年第55卷：704 - 711页）曾预测细胞质和液泡之间的比活性差异更大（高达20倍）。实际行为与预测行为之间的差异归因于样品中观察到的交叉污染程度，更重要的是，归因于蔗糖局限于细胞质的叶绿体外部区域。
