Discussion

African trypanosome procyclic forms are routinely cultured at 27°C. Heat shock at 37°C and above inhibits translation, and 1h at 41°C causes sequestration of mRNA in granules. By transcriptome analysis we found that mRNAs that bind to the heat shock regulator ZC3H11 remained in polysomes at 39°C and were protected from sequestration in granules at 41°C. The mRNAs that encode ribosomal proteins were excluded from heat-shock granules. 70 mRNAs moved towards the polysomal fraction at 39°C; many of these are also increased when trypanosomes migrate to the Tsetse salivary glands.