Abstract:
The process of cell division is highly regulated in eukaryotic cells. Failure to transmit chromosomes accurately during cell division can result in cell death or abnormal growth (e.g., tumors). Proteins that associate in multisubunit complexes required for chromosome replication, structure, and segregation (e.g. histones) are typically expressed in the cell at precise levels. Alteration of these levels could lead to inappropriate stoichiometries of the complex subunits, possibly resulting in an abnormal complex structure and/or function. Students in Drake University's BIO106: Research in Genetics course designed and implemented a genetic screen to identify genes important for chromosome transmission. This screen involves a visual assay of the segregation of a yeast artificial chromosome (YAC) in cells tranformed with high copies of yeast genes. An increased copy number of a gene is expected to be correlated with increased amounts of the protein product. Transformation of a YAC-containing yeast strain with a high copy yeast genomic library resulted in 12,625 transformants. A visual screen of these transformants for YAC instability indicated that 123 display higher levels of YAC loss than the control strain; 40 were severely defective in chromosome segregation. In addition to characterization of these high copy plasmid transformants, the specific yeast genes responsible for chromosome instability when present at high copy will be identified. This genetic screen is expected to elucidate proteins that are components of multisubunit complexes that play a role in chromosome transmission.
