CELL PHISIOLOGICAL AND MOLECULAR BIOLOGICA STUDIES ON THE DIVIDING APPARATUS OF PLASTIDS AND MITOCHONDRIA

质体分裂利用细胞器分裂装置，如质体分裂环（PD环）和线粒体分裂环（MD环）。质体分裂仪（PD仪）由外、中、内三个电子密环组成，线粒体分裂仪（MD仪）由细胞质中的三个电子密环、内外包膜间隙和线粒体基质中的内环组成。本文用电子显微镜详细地揭示了花青虫细胞器分裂过程中PD和MD装置的行为。当细胞进入有丝分裂时，首先形成内PD环，其次是外环和中环，最后形成MD环。PD环在MD环之前开始收缩。然而，MD环开始以PD环的4倍速度收缩，并赶上PD环。PD外环和MD外环的横截面积随着分割面收缩的推进而增大。这表明细胞器分裂器（OD器）的外环提供了收缩的动力。近年来从细胞中分离到带PD环的分裂叶绿体，这对完整的PD环的分离和PD环蛋白的鉴定具有重要意义。从细胞中分离出线粒体型和质体型的FtsZ基因，并从小鼠体内获得其抗体。免疫电镜显示，FtsZ蛋白分别不在PD环和MD环上。

Plastidokinesis makes use of organelle dividing apparatuses such as plastid-dividing ring (PD ring) and mitochondrion-dividing ring (MD ring). The plastid-dividing apparatus (PD apparatus) is composed of three electron-dense rings (the outer, middle and inner), while the mitochondrion-dividing apparatus (MD apparatus) is triple electron-dense rings in cytoplasm, inter-space between inner and outer envelopes and inner ring in the mitochondrial matrix.The behaviors of both the PD and MD apparatuses throughout organelle division in Cyanidioschyzon merolae has been revealed in detail by electron microscopy. When cells enter mitosis, the inner PD ring forms first, followed by the outer and middle rings and finally the MD rings. The PD rings begin to contract before the MD rings. However, the MD rings start to contract at about 4 times the speed of the PD rings and catch up to the PD rings. The cross-sectional areas of both the outer PD and MD rings increase as contraction in the plane of division progress. This suggests that the outer rings of organelle dividing apparatuses (OD apparatus) provide the motive forse for contractian. Recently the dividing chloroplasts with a PD ring have been isolated from the cells and it is essential for isolation of the intact PD ring and identification of proteins in the PD ring. The FtsZ genes of both mitochondrial and plastid types were isolated from the cell and their antibodies were obtained from mouse. Immuno-electron microscopy using their antibodies showed that the FtsZ proteins were not located on the PD ring and the MD ring, respectively.