| Budget Amount *help |
¥2,000,000 (Direct Cost: ¥2,000,000)
Fiscal Year 1987: ¥200,000 (Direct Cost: ¥200,000)
Fiscal Year 1986: ¥200,000 (Direct Cost: ¥200,000)
Fiscal Year 1985: ¥1,600,000 (Direct Cost: ¥1,600,000)
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| Research Abstract |
1. Correlation of the number of primordial germ cells (PGCs) at stage 47 with the amount of germ plasm at the 8-cell stage was analysed using two different laboratory-rased colonies of Xenopus laevis, HD and G groups. The average number of PGCs in J group tadpoles was significantly larger than that in HD group tadpoles. The amount of germ plasm was also demonstrated to be larger than in HD group. The amount of germ plasm was related positively to the number of PGCs. Embryos which contained larger amounts of germ plasm developed larger numbers of PGCs at stage 47. These findings suggest that the number of PGCs is regulated by at least two different mechanisms; first, the number of PGCs is primarily specified by the intrinsic amount of germ plasm in the fertilized egg. Second, it is regulated by an unknown mechanism which controls the totoal number of cells of whole embryos, such as the nucleocytoplasmic ratio.
2. A reliable biological assay system for "germ cell determinants" was newly developed. When 90 -rotated eggs were developed to 2 cell stage, fluorescence-dextran-amine (FDA), a reliable cell tracer, was injected into one blastomer, originally animal- or vegetal-blastomere. As a control, FDA was injected into one blastomere of normally oriented egg. After reaching stage 47, tadpoles were examined for the fluorescence. In the control tadpoles, about half of the PCSs had a strong fluorescence from FDA. On the other hand, no fluorescence was detected in the PGCs of the tadpoles which had been injected with FDA into the original animal-hemispere.
3. Monoclonal antibodies is going to be raised against cytoplasmic fraction including the germ plasm: 20.000xg precipitate cytoplasmic fraction from the gegetal hemispere of the fertilized eggs were injected into Balb/C mice, and the splenocytes were fused tomyeloma cells to get potency hybrydomas.
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