| Budget Amount *help |
¥15,500,000 (Direct Cost: ¥15,500,000)
Fiscal Year 2006: ¥6,700,000 (Direct Cost: ¥6,700,000)
Fiscal Year 2005: ¥8,800,000 (Direct Cost: ¥8,800,000)
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| Research Abstract |
In this project, I intended a genome-wide analysis of genetic interactions that control the development and differentiation of a model organism, Dictyostelium discoideum, and performed the construction of an upstream sequence database, gene clustering according to expression properties, and extraction of cis-elements specific to each cluster. DNA micro-array analysis was performed using the sexual-cycle RNAs as probes, information of which was so far very scarce. The gene expression pattern was obtained for 1,300 genes whose expression had not been detected in preceding studies. Among them, 40 genes were upregulated more than twice upon sexual maturation and 123 genes, down-regulated to less than half. Fifty-one genes were repressed to below 20%. Quantification by a real time PCR confirmed the expression patterns of 24 upregulated and 13 down-regulated genes. A consensus sequence of "aggtc(t/a)a" appeared repeatedly in the upstream sequences of those gamete-induced genes. In addition, I analyzed the ras family genes known to be involved in the intracellular signaling, and found that the RasX-group genes consisting of 6 members (rasU, rasV rasW, rasX, rasY, and rasZ) and slightly distant from well-analyzed RasG-group ones, are expressed predominantly during the sexual cycle, suggesting their differential role in the signal transduction cascade. Since these genes are clustered in the chromosome, total disruption of the rasX family genes was possible by a single homologous-recombination event. The resultant knockout mutants were normal in growth and asexual development.
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