| Budget Amount *help |
¥4,240,000 (Direct Cost: ¥3,700,000、Indirect Cost: ¥540,000)
Fiscal Year 2007: ¥2,340,000 (Direct Cost: ¥1,800,000、Indirect Cost: ¥540,000)
Fiscal Year 2006: ¥1,900,000 (Direct Cost: ¥1,900,000)
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| Research Abstract |
1. To assess generality that testis specific-intronless genes are demethylated during spermatogenesis and axe re-methylated in sperm nuclei, we isolated testis specific genes from public databases, of which 39 intronless genes are determined to be exclusively expressed in testicular germ cells and examined methylation status of them. Eighty percent of these genes, which contain CpG-rich sequence within the gene, are hypomethylated in male germ line cells that include PGCs in genital ridge, gonocytes, spermatogonia, spermatocytes and spermatids. These genes are remethylated after cease their expression in late spermatogenesis. Other testis specific intronless genes are CpG-poor and hypermethylated in all cell types examined.
2. Testicular germ cell-specific intronless genes, which are unmethylated during spermatogenesis are found to be associated with histone-DNA region by chromatin immunoprecipitation (ChIP) assay and remethylated in these specific regions in sperm nuclei.
3. To examine the effects of remethylation of testis specific intronless genes in sperm nuclei on gene expression in early development, we perform pronuclear injection of expression constructs of Tact1 gene with or without DNA methylation. We show that the expression of methylated gene is hardly observed in fertilized eggs, indicating that remethylation of genes in sperm nuclei play important role on repression in early embryo.
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