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Ultrastructural observations of the isthmus of dividing chloroplasts

分裂叶绿体峡部的超微结构观察

基本信息

批准号：
05640744
负责人：
HASHIMOTO Haruki
金额：
$ 1.22万
依托单位：
The University of Tokyo
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (C)
财政年份：
1993
资助国家：
日本
起止时间：
1993 至 1994
项目状态：
已结题

项目摘要

Ultrastructure of the isthmus of constricting chloroplasts of a green alga Closterium ehrenbergii was three-dimensionally observed by transparent electron microscopy of serial sections. The isthmus was encircled outside (cytoplasmic side) by a large number of concentrically orientated electron-opaque fibrous structures. Three-dimensional reconstruction showed that these structures as a whole form belts turning around the isthmus several times. This type of the distribution of electron-opaque fibrous structures around the isthmus of the dividing chloroplasts is quite different from those described for the other plants. No electron-opaque ring-like structures were detected on the stromal surface of the inner envelope membrane as observed in higher plants. Microtubule inhibitor amiprophos methyl (APM) which was observed not to inhibit plastokinesis (Hashimoto, 1992) did not disrupt the electron-opaque fibrous structures, indicating the structures be not relevant with microtubules. The ring-like distribution of the electron-opaque fibrous structure apparently coincide with the observation that the isthmus region of the dividing chloroplast was stained with rhodamine-conjugated phalloidin.Endoplasmic reticulum (ER) covers almost all over the surface of 'interphase' chloroplasts. When the chloroplast entered division phase, ER was separated at the isthmus region of the dividing chloroplast. As chloroplasts constricted. daughter nuclei moved into the groove the chloroplasts. Such nuclear migration was suggested to be driven by a rodshaped microtubule center. These observations suggest that in Closterium the cycle of chloroplast division and other organelles may be cooperatively regulated.

用连续切片的透明电子显微镜三维观察了绿色新月藻收缩叶绿体峡部的超微结构。峡部被大量同心定向的电子不透明纤维结构包围在外侧（细胞质侧）。三维重建显示，这些结构作为一个整体，形成带绕峡部几次。这种围绕分裂叶绿体峡部的电子不透明纤维结构的分布类型与其他植物的描述完全不同。没有电子不透明的环状结构被检测到的基质表面的内包膜膜观察高等植物。观察到不抑制质体分裂的微管抑制剂甲基胺丙磷（APM）（Hashimoto，1992）没有破坏电子不透明的纤维结构，表明该结构与微管无关。电子不透明纤维状结构的环状分布与叶绿体分裂的峡部被罗丹明标记的鬼笔环肽染色相一致。内质网（ER）几乎覆盖了“间期”叶绿体的整个表面。当叶绿体进入分裂期时，内质网在分裂的叶绿体峡部分离。叶绿体收缩。子核移到叶绿体的沟中。这种核迁移被认为是由杆状微管中心驱动的。这些观察结果表明，在新月藻的叶绿体分裂周期和其他细胞器可能是协同调节。