ZFIN Image: von der Hardt et al., 2007, Fig. 5

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Figure Caption

Fig. 5 Bmp Signaling Has a Negative Effect on Cadherin-Dependent Stability of Lamellipodia-Mediated Cell-Cell Contacts In Vivo and on Cell-Cell Adhesion of Mesodermal Cells In Vitro. (A–D) Confocal time-lapse recordings of mGFP-labeled lateral mesodermal cells in embryos between 85% and 90% stage. Shown are (A) alk8 morphant cells/embryo; (B) cells/embryo injected with CAalk8-mRNA; (C) alk8 morphant cells expressing nonsecreted dominant-negative C-Cadherin after transplantation in alk8 morphant host; and (D) cells coinjected with CAalk8 and ncad mRNA after transplantation in CAalk8 mRNA-injected host. The two cells indicated with asterisks in the first photos of (A)–(D) form lamellipodia that contact each other. In (A) and (D), this contact point is stable, and cell bodies are displaced toward each other, while in (B) and (C), it is only transient, and cells remain in distance. Average direct contact durations (in min) and spatial approaches of cells during lamellipodia retractions (in μm) were: (A) >13.3 min, 9.4 ± 4.1 μm, n = 9; (B) 2.5 ± 1.6 min, 1.5 ± 0.5 μm, n = 8; (C) 5.5 ± 1.9 min, 1.3 ± 0.5 μm, n = 6; (D) >15.5 min, 11.1 ± 2.8 μm, n = 8. For (A) and (D), most cell contacts still existed at the end of the time-lapse recordings. Scale bar represents 10 μm. (E–H and J–L) Primary cultures of mesoderm progenitor cells labeled with fluorescein or rhodamin dextran and plated on fibronectin, after 4 hr (E–H) or overnight (J–L) incubation. Scale bar in (E) represents 100 μm. Embryos had been injected with alk8-MO (E, G, H, J, and L) or CAalk8-mRNA (F, K, and L). (G and H) Medium supplemented with EGTA (G) or RGD (H). Aggregation of alk8-MO cells is strongly inhibited by a reduction of extracellular Ca²⁺ levels but is independent of integrin-fibronectin binding. (I) Ratios of loose (yellow), small (≤10 cells; red), and large (>10 cells; blue) aggregates in alk8-MO, CAalk8-mRNA, alk8-MO + EGTA, and alk8-MO + RGD cultures after 4 hr. Cells numbers in aggregates were determined at higher magnification as described elsewhere [30].

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