Tbx6/Ripply mechanism as dynamic-to-static converter in somite segmentation

Abstract

The metameric pattern of somites is created based on oscillatory expression of clock genes in presomitic mesoderm. However, the mechanism for converting the dynamic oscillation to a static pattern of somites is still unclear. Here, we provide evidence that Ripply/Tbx6 machinery is a key regulator of this conversion. Somite boundary determination by Ripply1/Ripply2-mediated removal of Tbx6 protein leads to cessation of clock gene expression in zebrafish embryos. On the other hand, activation of ripply1/ripply2 mRNA and protein expression is periodically regulated by clock oscillation in conjunction with an Erk signaling gradient. Whereas Ripply protein decreases rapidly in embryos, Ripply-triggered Tbx6 suppression persists long enough to complete somite boundary formation. Mathematical modeling shows that a molecular network based on results of this study can reproduce dynamic-to-static conversion in somitogenesis. Furthermore, simulations with this model suggest that sustained suppression of Tbx6 caused by Ripply is crucial in this conversion.

Mapmaking Process Reading from Local Distortions in Historical Maps: A Geographically Weighted Bidimensional Regression Analysis of a Japanese Castle Map

“…Goto [52] further demonstrated that the castle is represented on an enlarged scale, as other studies have pointed out. Yabe [53] visualized the distortions in the Takada Shoho Castle Map using quantitative methods, but did not use a local regression; as discussed later in the Methods section, only a global regression was used. Therefore, the local distortions were not accurately visualized.…”