Jaffe L A, Weisenseel M H, Jaffe L F
J Cell Biol. 1975 Nov;67(2PT.1):488-92. doi: 10.1083/jcb.67.2.488.
Pollen of L. longiflorum was grown in 45Ca-labeled medium and washed with nonradioactive medium. Whole, labeled pollen was then frozen and autoradiographed at -78 degrees C. The autoradiographs show striking accumulations of 45Ca in the growing tips of the pollen tubes. This result is obtained when the pollen is labeled for times as short as 1 min, or as long as 5 h. In most cases, the tip concentration is about two to four times greater than that in the bulk of the pollen tube, and extends for a length of about 20 mum. In autoradiographs of tubes longer than 1 mm, a small fraction of cells show a distinctly larger 45Ca accumulation, the tip containing more than 100 times that in the rest of the cell. The 1- to 5-h labeling experiments show that calcium is relatively concentrated within the cytoplasm of the growing tip. The 1- to 3-min labeling experiments suggest that calcium may enter the tip faster than it enters other regions. These patterns of calcium accumulation and flux may be related to the localized secretion of vesicles at the grow;ng tip.
将麝香百合花粉在含45Ca的培养基中培养，然后用无放射性的培养基洗涤。接着将完整的、带放射性标记的花粉冷冻，并在-78℃下进行放射自显影。放射自显影片显示，45Ca在花粉管的生长尖端有明显的积累。当花粉标记时间短至1分钟或长达5小时时，均可得到此结果。在大多数情况下，尖端的浓度比花粉管主体部分的浓度大约高两到四倍，且延伸长度约为20μm。在长度超过1mm的花粉管的放射自显影片中，一小部分细胞显示出明显更大的45Ca积累，其尖端所含的45Ca比细胞其他部分多100倍以上。1至5小时的标记实验表明，钙相对集中在生长尖端的细胞质内。1至3分钟的标记实验表明，钙进入尖端的速度可能比进入其他区域的速度更快。这些钙积累和通量的模式可能与生长尖端小泡的局部分泌有关。
