Determining the Meiotic Stability of HRAS1 Minisatellite Tract

Abstract

Minisatellites are repetitive DNA sequences with repeat units that range from 16 to 100 base pairs in length. These sequences are stable during mitosis but are highly unstable during meiosis with alteration in both length and sequence compositions. One class of minisatellite, rare alleles, have been correlated with cancers, including primary tumors of the brain, lung, ovaries, colon, bladder, and breast. Due to the difficulty of studying meiosis in humans, a novel minisatellite system in the yeast Saccharomyces cerevisiae using the common A1 allele, of the human HRAS1 minisatellite integrated into its genome adjacent to the HIS4 gene was used in this research. After the insertion of the HRAS1 minisatellite into the yeast genome, it was found to exhibit the same phenotypes as in mammalian cells. Our strains have a rare HRAS1 minisatellite allele isolated from breast cancer cells inserted into the promoter region of HIS 4. Two strains, namely .slx1 and .slx4 mutants of this his4-H10 HRAS1 rare minisatellite allele, were used to collect data. Data from other researchers showed that SLX4 andSLX1 play a vital role in resolving Holliday junctions recombination. Hence, to determine the factors involved in minisatellite stability, we determined the frequency at which the HRAS1 minisatellite repetitive tract undergoes alterations during meiosis, and the nature of the alterations, as well as calculated recombination and crossover frequency of this minisatellite in the our mutants.