The overall objective of this research is to understand how surface protein genes are regulated in response to a change in cell environment. The ciliated protozoan, Tetrahymena thermophila is being used as a model system because it contains a family of surface protein genes (serotype genes) whose expression is dependent on incubation temperature. Specific aims of this proposal are: l) Isolate and characterize Tetrahymena SerH3 genomic fragments by sequencing the flanking and coding regions and mapping transcription stop and start sites; 2) Identify regions of the SerH3 mRNA which are responsible for conferring temperature dependent expression by developing a cell free cytoplasmic extract and constructing SerH3 chimeric mRNAs; 3) Identify the specific trans-acting factors (positive or negative) responsible for SerH3 mRNA stability by using SerH3 regulatory mutants and identifying the factor(s) which bind to SerH3 messages. This research should provide insight into the mechanisms regulating genomic responses to environmental signals.
