Our major aim is to understand the molecular control of antigenic variation in Trypanosoma brucei. The approach provides insight into broader aspects of trypanosomatid molecular biology, however, and we are also developing generic tools for functional genomics.

The active, and many repressed VSGs, are found proximal to telomeres. We have used de novo telomere formation, telomerase knockout and homing endonuclease cleavage to manipulate the telomere in vivo. The results provide a number of insights into telomere biology and show that telomeric gene silencing operates in T. brucei. Current experiments are aimed at determining the role of the telomere in controlling VSG expression site transcription.

Histone acetylation modulates transcription, DNA repair, recombination and replication in other eukaryotes. Several putative histone acetyltransferases and deacetylases, identified following trypanosomatid genome sequencing, have been characterised in the lab. These proteins have been shown to play roles in cell-cycle control, telomeric gene silencing, RNAP I and RNAP II transcription control and DNA recombination. We are currently exploring the potential of deacetylases as drug targets and determining whether histone acetylation is linked to VSG expression control.

A range of molecular 'tools' are available for studies on T. brucei. DNA transfection via electroporation and high efficiency homologous recombination facilitate genetic manipulation while Tet-on inducible expression systems and RNA interference (RNAi see movie) have become popular functional analysis tools. We are developing these tools for functional genomics. In the first phase, >200 genes on T. brucei chromosome I were targeted for 'knock-down' using conditional RNAi followed by phenotype screening (See the TrypanoFAN website.). We are currently optimising conditions for RNAi library screening in bloodstream-form trypanosomes. All resources are being made available to the research community.