Fig. 5. Effect of heat shock on transcription and mRNA processing. (A,B) Trypanosome cultures were heat-shocked at 41°C or treated with 2 µg/ml sinefungin at 27°C, 37°C or 41°C. The decrease in mRNAs caused by the different treatments was analysed by northern blots probed for total mRNA (A), actin, tubulin and PDI-2 (B). Tubulin mRNAs aberrantly spliced by sinefungin (McNally and Agabian, 1992) are indicated by arrows.