| Budget Amount *help |
¥14,700,000 (Direct Cost: ¥14,700,000)
Fiscal Year 2003: ¥3,400,000 (Direct Cost: ¥3,400,000)
Fiscal Year 2002: ¥3,500,000 (Direct Cost: ¥3,500,000)
Fiscal Year 2001: ¥3,600,000 (Direct Cost: ¥3,600,000)
Fiscal Year 2000: ¥4,200,000 (Direct Cost: ¥4,200,000)
|
|---|
| Research Abstract |
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
|
