Average size of the nucleolus (cross-sectional area in μm2) and percentage of granular component (GC). A) Two-day experiment. B) Four-day experiment. Statistically significant differences in nucleolar size (p < 0.05), compared to the control, are indicated with a ‘§’ symbol when compared with the 1 g external control, and with ‘#’ when compared with the 1 g* control. Seedlings grown in the 0 g* tube show consistently a smaller nucleolus size. C) Representative electron microscope images of nucleoli from the 4-day-long experiment. Even though the nucleolus is clearly smaller in samples from the 0 g* tube, compared to the external control, the proportion and distribution of the different ultrastructural components of the nucleolus is similar in both conditions. GC: granular component. DFC: dense fibrillar component. Arrows indicate fibrillar centres.