Office: 163 BSC
Phone: (413) 597-2497
E-mail: marsha.altschuler@williams.edu
Area of Interest: Genetics
Genome organization and maintenance in Tetrahymena thermophila
My lab works on Tetrahymena thermophila, a single-celled protist noted for its nuclear dimorphism. Its micronucleus is specialized for germline functions (meiosis and mitosis; it is the source of genes passed on to future generations; it is diploid and contains five pairs of chromosomes); its macronucleus runs the day-to-day activities of the cell (all transcription happens here; it is discarded after sexual reproduction and replaced by a new copy made from the micronucleus).
Our interest is in the organization of the genome in the macronucleus. The macronucleus contains hundreds of chromosomes, each present in ~50 copies. The macronucleus lacks a mechanism to precisely partition this complex genome equally during nuclear division; thus how the cell manages to maintain a balanced genome after generations of divisions is a mystery. We are devising a quick-and-easy way to create deletions of macronuclear chromosomes by introducing telomeres at inappropriate places. This method will allow us to ask questions about (1) genome balance (do the genes found on a particular macronuclear chromosome need to be present on the same contiguous piece of DNA to function normally or can they be located on separate chromosomes? Do those syntenic genes need to be present in the same number of copies for normal cell function?) and (2) the mysterious mechanism for maintaining ~50 copies of each chromosome following the apparently imprecise amitotic macronuclear division (is there an inventory mechanism built into each macronuclear chromosome?...).
Link to the Tetrahymena Genome Database