A study of identification of the proteins and their genes which compose the dividing apparatus of mitochondria and plastids

通过透射电子显微镜可以检测到两个（或三个）电子致密环：外环位于外包膜的胞质表面，偶尔在膜间隙中有一个中环，内环位于内包膜的基质表面。FtsZ环在细菌分裂中起核心作用，也参与质体分裂，并且被认为是从蓝藻内共生下降到质体的。这两种结构之间的关系尚不清楚，尽管有关于它们是否相同的讨论，生物化学和免疫细胞化学的研究，使用同步叶绿体的红色Cyanidoschyzon merolae，表明质体FtsZ环是不同的，可分离的质体分裂环。FtsZ环定位于基质中，并在远离内被膜的一侧面向内质体分离环。FtsZ环和内、外质体分裂环在质体分裂前依次形成。FtsZ环消失在收缩的后期阶段之前的质体分裂环的解离，当收缩仍在进行中。我们的研究结果表明，FtsZ环为基础的系统，它起源于一个质体的祖先，蓝藻，和质体分裂环为基础的系统，可能起源于宿主真核细胞，形成一个复杂的，并参与质体分裂由不同的模式。

The plastid-dividing ring can be detected by transmission electron microscopy as two (or three) electron-dense rings: and outer ring on the cytosolic face of the outer envelope, occasionally a middle ring in the intermembrane space, and an inner ring on the stromal face of the inner envelope. The FtsZ ring, which plays a central role in bacterial division, also is involved in plastid division and is believed to have descended to plastids from cyanobacterial endosymbiosis. The relationship between the two structures is not known, although there is discussion regarding whether they are identical, biochemical and immunocytochemical investigations, using synchronized chloroplasts of the red alga Cyanidoschyzon merolae, showed that the plastid FtsZ ring is distinct and separable from the plastid-dividing ring. The FtsZ ring localizes in stroma and faces the inner plastid-dividing ring at the far side from the inner envelope. The FtsZ ring and the inner and outer plastid-dividing ring form in that order before plastid division. The FtsZ ring disappears at the late stage of constriction before dissociation of the plastid-dividing ring, when the constriction is still in progress. Our results suggest that the FtsZ ring-based system, which originated from a plastid ancestor, cyanobacteria, and the plastid-dividing ring-based system, which probably originated from host eukaryotic cells, form a complex and are involved in plastid division by distinct modes.