| Budget Amount *help |
¥3,600,000 (Direct Cost: ¥3,600,000)
Fiscal Year 2004: ¥1,000,000 (Direct Cost: ¥1,000,000)
Fiscal Year 2003: ¥2,600,000 (Direct Cost: ¥2,600,000)
|
|---|
| Research Abstract |
During early ascidian development, which is a prototype of early vertebrate development, one side of the two-cell embryo (2C cell), from which all cell types in the ascidian tadpoles are derived, should have multiple fates. The cleavage-arrested cell triplet was prepared from a 2C cell of the two-cell embryo and any pair of anterior neuroectoderm cells (2C-aa triplet), of presumptive notochordal neural cells (2C-AA triplet), of presumptive posterior epidermal cells (2C-bb triplet), or of presumptive major muscle cells (2C-BB triplet) derived from the 8-cell embryo, and cultured in contact. Differentiation of all three cells in the triplet was identified electrophysiologically by observing cell type-specific currents. In these 2C triplets, when the batch of two-cell embryos were fertilized and developed 3 hours later than that of 8-cell embryos for the cell pairs, the 2C cell from two-cell embryos developed into any of anterior neuronal, posterior neuronal, or muscle cells, depending upon the cell types of contacting cell pairs. However, when the two-cell embryos developed at earlier time than the 8-cell embryos, from which the cell pairs were derived, the 2C cells developed mostly into epidermal cell type. When they developed at the same time, the 2C cells were induced to differentiate into any of the above three types, or developed as the epidermal cell, with almost equal probability. In conclusion, the differentiation of the cleavage-arrested ascidian 2C cell was controlled to reveal the major cell types in the tadpole larva by selecting the types of contacting cell pairs as the inducers and the developmental time difference between the 2C cell and the contacting pair. The similarity of the cleavage-arrested ascidian 2C cell to the vertebrate embryonic stem cell was discussed in respect to the simple model for toti-potent stem cell differentiation.
|
