Differential regulation of ESAG transcripts in Trypanosoma brucei

In Trypanosoma brucei, several genes termed ESAGs for expression site-assoc iated genes are contained within the polycistronic transcription units of t he VSG gene, and their transcription is coordinately regulated during the p arasite life-cycle. Since the VSG mRNA is characterized by a drastic destab ilization under conditions where translation is inhibited, we examined if t his post-transcriptional control also applies to the ESAG mRNAs. While the ESAG 7/6 mRNA behaved like the VSG mRNA, the ESAG 8 and ESAG 3 mRNAs did no t. We ascribe this differential behaviour to the residual transcription tha t still occurs only in the ESAG 7/6 region of the VSG unit under conditions where this unit is down-regulated. (C) 1999 Elsevier Science B.V. All righ ts reserved.