| Budget Amount *help |
¥3,000,000 (Direct Cost: ¥3,000,000)
Fiscal Year 2001: ¥800,000 (Direct Cost: ¥800,000)
Fiscal Year 2000: ¥2,200,000 (Direct Cost: ¥2,200,000)
|
|---|
| Research Abstract |
Expression patterns of wnt7, wnt8, bmp2/4, brachyury, hnf3-β were studied from the gastrula to neurula stage in Chinese lancelets. Of them, bmp2/4 shows a specific expression pattern compared with that in vertebrates. Since regions where bmp2/4 is expressed in lancelets correspond to the region where the genes are inhibited their expression in vertebrates, this gene may play an basic function in anterior specific body formation in this animal. The other genes are similar to their vertebrate cognates in their expression pattern. The spatial expression pattern of these genes suggests that the early lancelet embryo has two distinct regions anteroposteriorly, each of which develops under different molecular mechanisms. The two distinct developmental domains may be related to the tripartite coelomic system that has been proposed as a basic body plan of deuterostomes.
To investigate function of maternal molecules in patterning expression of earliest zygotic genes, we screened maternal molecul
… More
es, β-catenin protein, nodal, Tbrain/eomesodermin (Tbr/eomes), FGF receptor mRNA have been identified. Although spatial pattern of their molecules show their own specificity, they first move to or are accumulated around the animal pole before or during the onset of the first cleavage, and then move or spread vegetally. Some of them become distributed asymmetrically between the cleaving blastomeres. Distribution of microtubules in eggs and embryos during the first cleavage shows a similar pattern, suggesting mechanical relationships between maternal factors and microtubules. The fact that LiCl treatment affects distribution of β-catenin, Tbr/eomes and microtubules supports a role of microtubules in distribution of the maternal factors after fertilization. Dorsal specific genes, otx, goosecoid and lim3, modify their expression pattern when treated with LiCl as in vertebrates. However, treated embryos still establish dorsoventral and left-right polarities. These results suggest that the lancelet embryo utilizes a similar set of molecules during the initial development but in different way from vertebrates, the distribution pattern of maternal molecules suggests that embryonic polarity is established during the first cleavage. Less
|
