FIG. 1. Delayed development of Xenopus embryos in response to Cyclin E Morpholino injection. Embryos were photographed either at 24 h (ab), or 50 h (ce) post-fertilization. Embryos were injected with the following amounts of morpholinos and were at these developmental stages: (a) 96 ng control-MO [St 21/22], (b) 96 ng CycE-MO [St 18 (arrowhead) to St 21], (c) 48 ng control-MO [St 35/36], (d) 24 ng CycE-MO [St 33/34] and (e) 48 ng CycE-MO [St 32]. In (c) the black arrowhead indicates the eye, the white arrowhead the cement gland, and the black arrow the proctodeum. For (c)e), note that this is a different experiment from that shown for the dose response distribution in Table 1. In (f) embryos were injected with 192 ng of control-MO (left side) or 192 ng of CycE-MO (right side). Embryos were photographed at 7.5 h (f) and 28 h post-fertilization (g). (h) Phosphorimaging of cyclin E-associated cdk2 histone H1 kinase activity. Five embryos from the experiment shown in (f) were immunoprecipitated with cyclin E antibodies at the indicated hour after fertilization (hpf) and associated kinase activity assayed using histone H1 as a substrate. As indicated below each sample, the amount of histone-H1 incorporated radioactivity (cpm) was quantified using a phosphorimager.