Fig. 1

Cultured newt cells and B2FF application. A, B Newt cells in the control medium (no B2FF). C, D Newt cells 48 h hours after the B2FF application. A, C Bright-field view. B, D Darkfield view. Scale bar in A = 500 μm. E, F Higher magnification view of the newt cells in the control condition. Scale bar in E = 100 μm. G The growth rate of the cultured newt cells in the control condition. H Mitogenic effects of B2FF onto the cultured newt cells. The rate of EdU+/Hoechst (nucleus) is shown. Whiskers show minimum and maximum values. The boxes represent 25–75% data ranges. p = 1.9x10⁻⁶ (Student’s two-tailed t-test). I Newt cells were kept for 2 weeks in the control condition. No cell aggregates could be observed (n = 0/8). J Newt cells were kept for 2 weeks in the B2FF-contained condition. A large cell aggregate could be seen (arrow, n = 8/8). Scale bar in I = 500 μm. K, L The bright-field images of the cells in the control (K) and the B2FF-contained (L) condition. Scale bar in K = 200 μm. M–P Gene expression pattern of the aggregate formed in the B2FF condition was investigated by in situ hybridization. P the negative control (no probes). Scale bar in M = 300 μm. Q The result from the in situ hybridization was confirmed by the quantitative RT-PCR. *** p < 0.01 * p < 0.05 (Student’s t-test)