INVESTIGATION ON THE STRUCTURE AND FUNCTION OF PYRENOIDS IN THE CHLOROPLAST OF LOWER PLANTS

低等植物叶绿体中芘类化合物的结构和功能研究

基本信息

批准号：
07304082
负责人：
HORI Terumitsu
金额：
$ 2.62万
依托单位：
UNIVERSITY OF TSUKUBA
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (A)
财政年份：
1995
资助国家：
日本
起止时间：
1995 至 1996
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-07304082/
关键词：
PYRENOID CHLOROPLAST ALGAE RUBISCO NUCLEOID DNA

项目摘要

Morphological research group : Recent studies indicate that the pyrenoid is an accumulation site of Rubisco in the chloroplast of lower plants. However, Hori demonstrated the localiation of chloroplast DNA in the pyrenoid core of some green algae. We have investigated the behavior of chloroplast DNA and pyrenoids throughout the life cycle of the unicellular green alga, Trebouxia. When the chloroplast divides, the pyrenoid with chloroplast DNA also divides. The chloroplast DNAs are always associated with the pyrenoids during the life cycle of Trebouxia (Miyamura). Ishikawa found the asscoclation of DNAs with lens-shaepd pyrenoids, which are scattered throughout the chloroplast matrix of the diatom, Nitschia sigmoidea. She also found the localization of Rubisco in the pyrenoid core of N.sigmoidea Recently, Suess et al (1995) reported that Rubisco molecules are not highly concentrated in the pyrenoid core of the unicellular green alga, Chlamydomonas reinhardtii. Their results are inconsis … More tent with recent studies in which most of Rubisco molecules are localized in the pyrenoid core. Thus, Nozaki re-examined the distribution of Rubisco in the cells of C.reinhardtii, and found the localization of most of Rubisco molecules in the pyrenoid core using cryo-fixation and immunogold electron microscopy. In Euglena, small subunit of Rubisco is found to be localized in the compartment alized osmiophilic body (COS) in the cytoplasm. This results suggests that the COS is either the cytoplasmic site of chloroplast protein synthesis or an intermediate compartment in the transport of chloroplast proteins from the ER to the chloroplast (Osafune). Hara re-evaluated the ultrastructure of the pyrenoid as the taxonomic character of unicellullar red algae in Porphyridiales using electron microscopy and molecular phylogenetic techniques. This study suggests that Porphyridiales is not a monophyletic group, although the algae belonging to this group is similar in appearance.Physiological research group : Rubisco is the major component of the pyrenoid, and in some algae DNA is also present, as described above. However, it is possible that other minor components are present in the pyrenoid core. Therefore, Okada developed the new biochemical techniques in order to identify the minor components of the pyrenoid. The minor components of the pyrenoid will be identified using this technique in near future. When the extracellular CO_2 concentration is lowered from 5% to ordinary air level in the cells of C.reinhardtii, the pyrenoid has become 1.4-1.6 times larger in volume, and the protein concentration has also increased (Tsuzuki). However, the amount of transcripts of small subunit of Rubisco genes decreases under lower CO_2 concentration. These results suggests that when the pyrenoid develops under lower CO_2 concentration, the Rubisco is accumulated in the pyrenoid instead of the synthesis of new molecules. It is known that the pyrenoid core is traversed by thylakoid membranes in most of algae. Nakayama showed that photosystem II is present in the thylakoid membranes in the pyrenoid. Less

形态学研究小组：最近的研究表明，核糖体是低等植物叶绿体中 Rubisco 的积累位点，然而，Hori 证明了叶绿体 DNA 在一些绿藻核糖核中的定位，并研究了叶绿体 DNA 的行为。核糖核蛋白贯穿单细胞绿藻 Trebouxia 的生命周期。当叶绿体分裂时，核糖核蛋白也会与叶绿体 DNA 一起分裂。在Trebouxia（Miyamura）的生命周期中，叶绿体DNA始终与类核蛋白相关联，她还发现了硅藻的叶绿体基质中散布着透镜状类核蛋白。最近，Suess 等人发现 Rubisco 在 sigmoidea 核核中的定位Nozaki 等人 (1995) 报道称，Rubisco 分子并未高度集中在单细胞绿藻莱茵衣藻 (Chlamydomonas Reinhardtii) 的核核中，他们的结果与最近的研究结果不一致，其中大多数 Rubisco 分子都位于核核中。重新检查了 Rubisco 在 C.reinhardtii 细胞中的分布，并使用冷冻固定和免疫金电子显微镜检查发现，Rubisco 的小亚基位于细胞质中的嗜锇小体 (COS) 中，该结果表明 COS 要么是叶绿体蛋白质合成的细胞质位点。叶绿体蛋白从内质网运输到叶绿体的中间室（Osafune）重新评估了超微结构。利用电子显微镜和分子系统发育技术，将类核蛋白作为紫球菌目中单细胞红藻的分类特征。本研究表明，紫球菌目不是一个单系类群，尽管属于该类群的藻类在外观上相似。生理研究类群：Rubisco是主要的。如上所述，某些藻类中也存在 DNA，但也可能存在其他次要成分。因此，冈田开发了新的生化技术，以鉴定核糖体的微量成分，当细胞外CO_2浓度从5降低时，将使用该技术鉴定核糖体的微量成分。与普通空气水平相比，莱因哈特氏菌细胞中的蛋白核体积增大了 1.4-1.6 倍，并且蛋白质浓度也增加了（Tsuzuki）。然而，在较低CO_2浓度下，Rubisco基因小亚基的转录物数量减少。这些结果表明，当核糖体在较低CO_2浓度下发育时，Rubisco在核糖体中积累，而不是合成新分子。大多数藻类的类囊体膜都穿过类核核，Nakayama 表明光系统 II 存在于类核体膜中。较少的