Fig. 5.

Fluorescence Cross-Correlation Spectroscopy (FCCS) analysis of Wnt3a in the extracellular milieu in Xenopus embryos. a FCCS analyses of the extracellular milieu within almost one-cell diameter from Wnt3a-expressing cells were carried out in Xenopus embryo at the mid-gastrula stage. Through a number of trials of FCCS and FCS (Fig. 6) analyses, we found that the behavior of Wnt proteins was quite different between the inside and outside of cells. Thus, we could ensure the extracellular measurements by examining the dynamics of Wnt proteins. b Molecular interaction between mCherry-Wnt3a and GFP-Wnt3a, secreted GFP or GFP-WntD is evaluated with RCA (relative cross-correlation amplitude), which corresponds to the ratio of interacting molecules to all molecules. c Effects of overexpression of Fzd8-CRD or sFRP2 on molecular interaction between mCherry-Wnt3a and GFP-Wnt3a. Statistical significance (p) was calculated by use of Tukey’s multiple comparisons of means. NS means not significant