Fig. 7. CA-CamKII promotes the destruction of both cyclin B1 and securin. Eggs were microinjected with cRNA to cyclin B1::YFP or securin::CFP and then with cRNA to CA-CamKII. (A) APC/C activity increased following introduction of CA-CamKII as judged by the degradation of cyclin B1 (n=6). Cyclin B1 levels dropped to a minimum at the time of second polar body extrusion and levels remain low until pronuclei formation. Representative brightfield and cyclin B1::YFP images are shown at various times after injection as indicated. (B) A similar degradation profile for securin::CFP is also observed following introduction of CA-CamKII cRNA (n=10). (A and B) CA-CamKII cRNA was microinjected at t=0; second polar body extrusion (PB2; arrow); pronuclei formation (PN; arrowhead). Scale bar: 20 µm.