アブストラクト
| Date | May 8, 2006 |
| Speaker | Dr. Tatsuo Shibata, Department of mathematical and life sciences, Hiroshima university |
| Title | Network basis of stripes formation and constructive decoding of developmental program |
| Abstract | Gene regulatory networks contain several substructures called network
motifs, which frequently exist throughout the networks. One of such motifs
found in both single cell organisms Escherichia coli and Saccharomyces
cerevisiae and multicellular organisms such as Strongylocentrotus purpuratus
and Drosophila melanogaster is the feed- forward loop, in which an effecter
regulates its target by a direct regulatory interaction and an indirect
interaction mediated by another gene product. In contrast, two network
motifs are found particularly in the multicellular organisms S. purpuratus
and D.
melanogaster. The two motifs consists of three genes, among which two genes
are mutually interacting each other, and both two genes are regulating or
regulated by another gene product. These network motifs do not often represent an independent unit that are functionally isolated from the rest of the network. Our database study of gene regulatory networks indicates that most of these motifs are actually cross talking. Therefore, the network motifs are considered as building blocks of a network. Interactions and cross talks of the motifs may give rise to a function of the network that a single network motif cannot generate. These network motifs do not often represent an independent unit that are functionally isolated from the rest of the network. Our database study of gene regulatory networks indicates that most of these motifs are actually cross talking. Therefore, the network motifs are considered as building blocks of a network. Interactions and cross talks of the motifs may give rise to a function of the network that a single network motif cannot generate. Here, we theoretically analyze the behavior of networks that contain these three network motifs cross talking to each other. In response to levels of the effecter, such networks can generate multiple rise-and-fall temporal expression profiles and spatial stripes, which are typically observed in developmental processes. We also show that the two motifs particularly found in D. melanogaster serves to sharpen the network response. Base on this theoretical frame work, we developed a mathematical model of the early development of D. melanogaster. The model explains how the distribution of the motifs in the network contributes to the pattern formation in the developmental process of the fly. |