Grant-in-Aid for international Scientific Research
|Allocation Type||Single-year Grants|
|Research Institution||Okazaki National Research Institutes National Institute for Basic Biology|
TAKEUCHI Ikuo National Institute for Basic Biology, 基礎生物学研究所, 所長 (90025239)
BONNER John T. Princeton University, 名誉教授
SARAN Shweta Indian Institute of Science, 博士研究員
WILLIAMS Jeffrey G. Imperial Cancer Research Fund, 教授
MAEDA Yasuo Tohoku University, Faculty of Science, 理学部, 教授 (50025417)
OKAMOTO Koji Kyoto University, Faculty of Science, 理学部, 助教授 (10029944)
TASAKA Masao Kyoto University, Faculty of Science, 理学部, 助教授 (90179680)
JOHN Bonner プリンストン大学, 名誉教授
JEFFREY Will 英国帝国がん研究所, 教授
|Project Period (FY)
1992 – 1993
Completed(Fiscal Year 1993)
|Budget Amount *help
¥3,100,000 (Direct Cost : ¥3,100,000)
Fiscal Year 1993 : ¥1,500,000 (Direct Cost : ¥1,500,000)
Fiscal Year 1992 : ¥1,600,000 (Direct Cost : ¥1,600,000)
|Keywords||Cell differentiation / Pattern formation / Gene expression / Cell cycle / Signal transduction / Cellular slime mold / 転写調節 / 形態形成運動|
In the development of cellular slime molds, cells aggregate to form a tissue, in which two types of cells(prestalk and prespore) differentiate in the anterior and the posterior parts. To elucidate mechanisms of the pattern formation, we made the following studies.
1.By the use of a vector with the actin-basal promoter provided by J.Williams, we analyzed the cis-acting regulatory regions of prespore-specific gene Dp87 and found 4 positive, prespore-specific and 1 negative, non-prespore-specific and 1 positive, cell-type-non-specific regions regulating its transcription.
2.The process of stalk differentiation was found to be divided into 4 different stages. Cyclic AMP was required at the second stage and DIF at the third stage, where an unidentified low molecular weight secretory substance was also required. Cyclic AMP given at the third stage rather inhibited both of prestalk-specific ecmA and ecmB genes to the same extent, while 8-Br-cAMP which activates protein kinase A specifically ind
uced ecmB expression, suggesting involvement of this enzyme in differential expression of the two genes.
3.Relationship between the cell-cycle phase and the pattern formation was investigated by using a transformat constitutively expressingbeta-galactosidase. It was found that cells starved before a particular point (PS) within the G2 phase initiated aggregation, but sorted out to the posterior prespore region of a migrating slug, while those starved after that point lagged behind in aggregation, but sorted out to the anterior prestalk region.
4.Changes in intracellular free calcium concentration ([(Ca)^<2+>]) and responsiveness to cAMP stumulation during development were studied, by using cells transformed with apoqequorin cDNA of a jellyfish. Cells exhibited a considerable increase in [(Ca)^<2+>] and acquired responsiveness to cAMP by showing a transient increase in [(Ca)^<2+>], at the time of aggregation. Prestalk cells contained twice as much [(Ca)^<2+>] and showed three times as large a response to cAMP as prespore cells. Less