| Project/Area Number |
15207020
|
|---|
| Research Category |
Grant-in-Aid for Scientific Research (A)
|
| Allocation Type | Single-year Grants |
|---|
| Section | 一般 |
|---|
| Research Field |
Evolutionary biology
|
|---|
| Research Institution | Osaka University |
|---|
Principal Investigator |
YOMO Tetsuya Osaka University, Grad.School of Information Science and Technology, Associate Professor, 大学院・情報科学研究科, 助教授 (00222399)
|
|---|
| Project Period (FY) |
2003 – 2005
|
| Project Status |
Completed (Fiscal Year 2005)
|
| Budget Amount *help |
¥50,310,000 (Direct Cost: ¥38,700,000、Indirect Cost: ¥11,610,000)
Fiscal Year 2005: ¥14,690,000 (Direct Cost: ¥11,300,000、Indirect Cost: ¥3,390,000)
Fiscal Year 2004: ¥14,690,000 (Direct Cost: ¥11,300,000、Indirect Cost: ¥3,390,000)
Fiscal Year 2003: ¥20,930,000 (Direct Cost: ¥16,100,000、Indirect Cost: ¥4,830,000)
|
|---|
| Keywords | Symbiosis / E.coli / Dictyostelium / Tetrahymena / Cyanobacteria / Directed evolution / Origin of life / 細胞性粘膜 / セルソーター / 緑色蛍光タンパク質 / セルソータ / ジーンチップ / 光合成細菌 |
|---|
| Research Abstract |
In order to examine how symbiosis emerges, we established two reproducible experimental symbiotic systems.
1)Two well-characterized and phylogeneticaly different species, Escherichia coli and Dictyostelium discoideum, were used as the model organisms. When these two species were allowed to grow on minimal agar plates, they achieved a stable state of coexistence, in which the emerging E.coli colonies housing Dictyostelium cells were of a mucoidal nature that was not observed originally. We used this microbiological system as a model to study the initial stages of the development of the symbiotic relationship. The E.coli gene expression profiles of symbiotic cells and non-symbiotic cells captured using GeneChip technology were compared. It was clearly shown that the gene expression profile was substantially altered in E.coli cells undergoing symbiotic transition. The genes responsible for central energy metabolism as well as those responsible for translation apparatus were down-regulated
… More
in symbiotic E.coli. The transcriptional patterns of genes coding for the E.coli cell surface structure were drastically altered, and this alteration may determine the mucoidal nature and unique structure of coexisting colonies. General stress inducible genes were expressed at low levels in symbiotic E.coli. These observed changes in the transcription profile indicate that the central metabolism of symbiotic E.coli is attenuated as a whole, and the cells are probably under less stress because of the benefits brought by coexistence with the symbiotic counterpart Dictyostelium.
2)To investigate artificial symbiosis relationships among phylogeneticaly unrelated species, we also created a experimental symbiosis between Tetrahymena and cyanobacteria. We have found that long-term co-cultivation under anaerobic condition results in a stable coexistence of both species, in which cyanobacteria is alive in Tetrahymena. To examine the emergence of symbiotic relationship in depth, we started to search the optimum conditions for co-cultivation and develop the methods of analysis. Less
|
