The co-localization of PDD1 and PDD3 genes in Tetrahymena thermophila 

Adedayo Adesokan and Doug Chalker

Biology Department, Washington University in St. Louis

            Throughout my time in the Biology program, I took on several different experiments and projects, which do not appear related from an impartial standpoint.  The main experiment—which occupied the majority of my time and interest—was the localization of a cell protein called PDD3.  The protein was studied in Tetrahymena Thermophila, a eukaryotic single-celled organism that contains two nuclei.  Tetrahymena’s PDD3 gene appears to play a role in the partitioning of specific DNA sequences in developing the organism into specific domains in the nucleus.  After cloning the gene of interest and fusing it to a YFP (yellow fluorescent protein), we attempted to study its localization—that is, where the gene traveled once it entered the cell.  Fluorescent proteins such as YFP, GFP (green fluorescent protein), and CFP (cyan fluorescent protein) allow one to “tag” specific genes with their respective colors, and then locate these genes using fluorescent lights of different wavelengths under a microscope.  Each fluorescent protein is only illuminated under its correspondent fluorescent light and can thus be identified.  In an attempt to study an equally important protein known as PDD1, we fused this to a CFP and studied its co-localization with PDD3.  Though past observations showed that the PDD3 gene co-localized by wrapping itself around the PDD1 gene throughout the cell, our experiment provides evidence that the cells co-localization is fully overlapping and uniformly distributed throughout the cell.  That is, PDD3 and PDD1 undergo their biological functions in identical cell regions and may perhaps be jointly essential to the partitioning of the cell’s DNA sequences.  By repeating further trials of this experiment, my lab hopes to make an observation that will change the face of this organism’s genome.