Figure 1. Heat triggers a general inhibition of protein synthesis.

(A) Metabolic labeling of de novo synthesized proteins from Arabidopsis seedlings grown at 22°C or after a heat shock of 38°C during the indicated times. High molecular weight heat-shock proteins are indicated by an asterisk. (B) Verification of the quality of the polysome preparation. Equal volumes of the last 16 fractions of the sucrose gradient from control or heat-stressed Arabidopsis seedlings were subjected to electrophoretic analysis. According to the distribution of 18 S and 28 S rRNAs, fractions 1–8 were designated as non-polysomal (NP), while fractions 11–16 were considered as polysomal (HP) fractions. (C) Quantification and graphic representation of the polysome profiles from the samples in (B). (D) Polysome content (PC) of control or heat-stressed Arabidopsis seedlings was calculated as described in materials and methods. Values are mean percentages from three biological samples (*P<0.05).