睡蓮含晶體之厚壁細胞內鈣的次細胞定位

Subcellular Localization of Calcium in the Crystal-Forming Sclereids of Nymphaea tetragona Georgi

本研究是透過鋨酸∕焦銻酸鉀（OTPA）與細胞內鈣離子作用產生微細沉澱，再經由電子顯微鏡技術的觀察，來探究睡蓮（Nymphaea tetragona Georgi）葉部厚壁細胞發育過程中，鈣離子的次細胞定位。在葉片柵狀組織之葉肉薄壁細胞內，焦銻酸鈣的沉澱物分佈於細胞膜與細胞壁之間、細胞核、粒線體、液胞、內質網、高爾基氏體及分泌囊胞內。厚壁細胞分散地始源自未分化的葉肉薄壁細胞，許多結晶腔位於其初生細胞壁與細胞膜之間。晶體鞘膜包圍草酸鈣晶體，並與細胞膜相連接。厚壁始源細胞內，微細的鈣沉澱物主要密集地堆積於晶體鞘膜上，但在中央液胞內，則只可觀察到少許鈣的沉澱物。厚壁細胞之細胞壁內的晶體形成後，即進行次生細胞壁的堆積，並將晶體包埋於初生與次生細胞壁之間。成熟厚壁細胞的液胞內、細胞膜、初生細胞壁及晶體鞘膜上均可明顯觀察到焦銻酸鈣的沉澱物。

By using a modified osmium tetroxide-potassium pyroantimonate (OTPA) precipitation technique, calcium ions were subcellularly localized in the crystal-forming sclereids of the leaf of Nymphaea tetragona Georgi. In young leaf laminae, the mesophyll parenchyma cells contained calcium antimonate precipitates in the vacuoles, mitochondria, nuclei, endoplasmic reticulum, dictyosome and the secretary vesicles. Besides, calcium precipitates were also associated with the plasmalemma and plasmodesmata. From the rudimentary mesophyll cells, the sclereid idioblasts originated sporadically. In these sclereid initial cells, many prismatic oxalate crystals bounded by the crystal sheaths were observed in the crystal chambers between the plasmalemma and primary cell wall. The calcium antimonate precipitates were densely presented on the crystal sheaths, however, only few calcium precipitates were found in the central vacuoles of the sclereid initial cells. After the formation of crystals, the secondary wall was deposited and then the crystals were embedded between the primary and secondary cell walls. In the mature sclereid, calcium antimonate precipitates were obviously associated with the crystal sheaths, primary cell wall, plasmalemma, and also accumulated in the central vacuole.