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，类拟南芥是鲁比斯科在较低植物的叶绿体中的一个积累部位。然而，Hori证明了叶绿体DNA在某些绿藻的类球核中的定位。我们已经研究了整个单细胞绿藻（Trebouxia）的生命周期中叶绿体DNA和类拟南芥的行为。当叶绿体分裂时，与叶绿体DNA的类拟南芥也会分裂。叶绿体DNA在Trebouxia（Miyamura）的生命周期中始终与类拟甲状腺素相关。 Ishikawa发现了DNA与镜头 - 沙皮德犬类类动物的coclation，它们散布在硅藻的叶绿体基质中Nitschia sigmoidea。她还发现Rubisco最近在N.sigmoidea的匹甲型核心中定位，Suess等人（1995年）报道，Rubisco分子在单细胞绿色藻类的类肾上腺核心中没有高度浓缩。他们的结果是不合理的……最近的十个研究中，大多数Rubisco分子都定位在类球核心中。这是Nozaki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元电子显微镜发现了大多数Rubisco分子在类拟南芥中的定位。在Euglena中，发现Rubisco的小亚基位于细胞质中的隔离渗透体（COS）中。该结果表明，COS是叶绿体蛋白合成的细胞质位点，或者是叶绿体蛋白从ER到叶绿体（Osafune）转运中的中间室。 Hara使用电子显微镜和分子系统发育技术重新评估了类肾上腺素的超微结构为单细胞红藻的分类特征。这项研究表明，porphyridiales不是一个单系组，尽管属于该组的藻类在外观上相似。生理学研究小组：Rubisco是类肾上腺素的主要成分，在某些藻类DNA中也存在，如上所述。然而，在类球核中可能存在其他次要成分。因此，冈田开发了新的生化技术，以识别类孢子的次要成分。在不久的将来，将使用此技术来识别类似力的次要组成部分。当细胞外CO_2浓度从C.Reinhardtii细胞中的5％降低到普通的空气水平时，菌类动物的体积已大1.4-1.6倍，并且蛋白质浓度也增加了（Tsuzuki）。然而，在较低的CO_2浓度下，Rubisco基因的小亚基的转录本量减少。这些结果表明，当类球发生在较低的CO_2浓度下时，rubisco会积聚在类比纳类动物中，而不是新分子的合成。众所周知，在大多数藻类中，类囊体膜遍历类囊体膜。中山表明，光系统II存在于类囊体膜中。较少的