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Fig. 2. Impairment of embryonic development by interference with Elk-1 activity. (A) The XElk-1 constructs used in these experiments. Top: myc-tagged XElk-1; middle: myc-tagged XElk-1-EnR; bottom: î EtsXElk-1-EnR. (B) Injection of XElk-1-myc mRNA (0.5 ng into each cell of the two-cell stage; total 1 ng) has no effect on early Xenopus development. (C, D) A non-tagged version of XElk-1 also has no effect on development. Compare C (uninjected) with D (injected). (Eâ G) Interference with XElk-1 activity by means of a dominant-interfering construct disrupts Xenopus development. (E) Uninjected embryos. (F) Embryos injected with 750 pg RNA encoding XElk-1-EnR; such embryos form a dorsally curved trunk and open neural folds. (G) Embryos injected with 750 pg RNA encoding î EtsXElk-1-EnR appear normal. (Hâ J) Trunk and anterior defects caused by XElk-1-EnR (I) are rescued, at least partially, by co-expression of X-Elk1 mRNA (J). (Kâ N) Notochord (marked by MZ15) and muscle (marked by 12/101) differentiation is diminished in embryos in which XElk-1 activity is perturbed. Antibody staining was carried out on 50-î¼m sections of stage 35 embryos previously injected with 750 pg RNA encoding XElk-1-EnR. Little notochord can be detected in embryos expressing XElk-1-EnR (L; compare with control embryo in K). Muscle differentiation is also greatly inhibited (N; compare with control embryo in M). (O, P) Xbra expression is also greatly inhibited in embryos injected with 750 pg RNA encoding XElk-1-EnR (O; compare with control embryos in P). All results were obtained in three independent experiments with over 200 embryos examined per treatment, except for data in panels C and D, which were derived from two experiments with 60 embryos in each case. |
