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Fig. 4.
AChE is not required for cell-cell adhesion, but is necessary for cell-substrate adhesion to fibronectin. Dissociated intestinal endoderm cells from control MO-injected (A) or AChE MO-injected (B) embryos reaggregated 30 min (30′) after introduction of Ca2+ ions into the medium (0′; see supplementary Materials and Methods). Brightfield/fluorescent images show that both injected and uninjected cells from each injection group reaggregated. Assays were performed using at least three different embryos per condition. Transverse sections through wild-type guts (NF 41) were immunostained for laminin (LM; C,C′) or fibronectin (FN; D,D′). LM (red) is found at basement membranes (arrow) surrounding the gut tube. FN (green) is found at the basement membrane (arrow), but is also enriched at endoderm cell basal poles (arrowheads). Endoderm cells from control MO-injected or AChE MO-injected intestines were plated on LM (E) or FN (F). There is no difference in cell adhesion on LM (E), but cells from AChE MO-injected embryos are less adherent than control cells on FN (F). Mean±s.e.m. for the percentage of adherent cells for six to eight independent embryos. *P<0.05. Scale bars: 1000 μm in A,B; 100 μm in C,D; 25 μm in C′,D′. |
