Meeting Abstract
118.1 Monday, Jan. 7 The evolution of mononucleotide repeats and gene stability in eukaryotes WALKER, J.F.*; ZANIS, M.J.; Purdue University; Purdue University jfwalker@purdue.edu
The signature of natural selection shaping genome sequences can be detected through the statistical analysis of the pattern and distribution of mutations in DNA. At times, they can have a positive effect and allow organisms to survive by adapting to their environment; however, more often mutations have a negative or deleterious effect. Because of the negative effects of mutations on cell machinery, and ultimately the fitness of the organisms, the mechanisms eukaryotic organisms use for efficient and reliable DNA replication have evolved for stability. In this study, we survey the presence and evolution of long mononucleotide repeats in coding DNA. Previous research has indicated that natural selection will act against runs of monomeric nucleotide repeats because of their increased likelihood of slippage and the introduction of frameshift mutations into gene sequences. In order to examine the structure of genes, we maintained the integrity of the amino acid sequence and created sequences with the expected number of mononucleotide repeats that were then compared to the number of mononucleotide repeats actually observed. We also examined the hypothesis that long runs of monomers lead to frameshift mutations. By comparing the genomes of closely related species, we were then able to determine whether the genes that have a long mononucleotide repeat in one species led to a frameshift mutation in the same gene of a closely related species. We found that almost all eukaryotic species have a strong resistance to long mononucleotide repeats; this remains true across the entire tree of life with the exception of two lineages. We present data with the following goals: 1) to expound on the role of monomers contributing to frameshift mutations and 2) to discuss how natural selection acts to maintain genome stability in most eukaryotic lineages.
