Post-genome project of the endocellular symbiotic bacterium, Buchnera.

在细胞内共生中，两个或多个基因组及其基因表达机制不仅和谐地共存于单个细胞中，而且相互作用。在我们主要研究的蚜虫细菌细胞共生系统中，数十个巨大的蚜虫特化细胞（称为细菌细胞）的细胞质中含有许多原核共生体。共生微生物Buchnera与E.根据16 S rDNA的分子系统发育分析，Buchnera与蚜虫的共生关系可以追溯到2亿年前。这些年来，这两个伙伴已经变得如此相互依赖，它们不再能够彼此独立地生活。我们对这个共生系统进行了大约25年的广泛研究，涉及Buchnera的进化，基因和基因组的结构，基因表达以及该系统在宿主代谢方面的意义。日 关于我们 这些研究可细分为4个术语。在第三阶段，我们对Buchnera的基因组进行了分析，并在世界上首次成功地揭示了一个专性共生细菌的全貌，这表明Buchnera虽然与E.大肠杆菌，已经失去了后者中发现的七分之六的基因。Buchnera的基因组分析也揭示了许多对理解细胞进化有重要意义的宝贵事实。本文总结了第四学期的结果，该学期结束了蚜虫-Buchnera共生的系列研究。在细菌细胞的转录组分析中获得了这一术语中最显著的结果。在细菌细胞中特异性高表达的基因包括：（1）氨基酸代谢基因，包括Buchnera不能产生的氨基酸的生物合成基因和Buchnera能合成的氨基酸的利用基因;（2）与转运相关的基因，包括线粒体转运蛋白基因和编码调节囊泡转运的G蛋白Rab的基因;和（3）降解细菌细胞壁的推定溶菌酶的基因。少

In intracellular symbiosis, two or more genomes and their gene expression machinery coexist in a single cell not only harmoniously but mutualistically. In the symbiosis system of the aphid bacteriocyte that has been our main research materials, several tens of huge, specialized cells of aphids, called bacteriocytes, contain many prokaryotic symbionts in the cytoplasm. The symbiotic microorganism, designated Buchnera, is shown to be closely related to E. coli phylogenetically, and molecular phylogenetic analysis based on the structure of 16S rDNA suggests that the symbiosis of Buchnera with the aphid dates back to 200 million years ago. For these years the two partners have become so dependent mutualistically, they can no longer live independently from each other.We have studied on this symbiosis system extensively for about 25 years with respect to evolution of Buchnera, structure of genes and genomes, gene expression, and the system's significance in terms of the host's metabolism. Th … More ese studies may be subdivided into 4 terms. In the third term, we analyzed the Buchnera genome and successfully unveiled its whole picture for the first time in the world for an obligately symbiotic bacterium, which indicated that Buchnera, in spite of its close relationship to E. coli, has lost six sevenths genes that are found in the latter. The Buchnera genome analysis revealed also many invaluable facts significant in understanding cellular evolution.This report is to summarize the results obtained in the fourth term that concludes the series of studies on the aphid-Buchnera symbiosis. The most significant result in this term was obtained in transcriptome analysis of the bacteriocyte. A number of genes were highly expressed specifically in the bacteriocyte, which include (1)genes for amino acid metabolism, including those for biosynthesis of amino acids that Buchnera cannot produce, and those for utilization of amino acids that Buchnera can synthesize ; (2)genes related to transport, including genes for mitochondrial transporters and a gene encoding Rab, a G protein that regulates vesicular transport ; and (3)genes for putative lysozymes that degrade bacterial cell walls. Less