Fig. 13. Vaccinia infection reduces centrosome microtubule nucleation efficiency. In uninfected cells, microtubules (A, E and I) nucleate from centrosomes (B, F and J) after nocodazole washout for the times indicated. In contrast, 2 h after infection with vaccinia, microtubules (C, G and K) are nucleated inefficiently from centrosomes (D, H and L). All images were collected with identical camera settings, to allow comparison of fluorescence intensity between centrosomes. Inserts (B, D, F, H, J and L) are adjusted as in Figure 12 to facilitate visualization of the weak γ-tubulin centrosomal labelling. Arrowheads indicate the position of the centrosome. Scale bar = 10 µm.