The Spontaneous Mutation Rate in the Fission Yeast Schizosaccharomyces pombe.
The rate at which new mutations arise in the genome is a key factor in the evolution and adaptation of species. Here we describe the rate and spectrum of spontaneous mutations for the fission yeast Schizosaccharomyces pombe, a key model organism with many similarities to higher eukaryotes. We undertook an ∼1700-generation mutation accumulation (MA) experiment with a haploid S. pombe, generating 422 single-base substitutions and 119 insertion-deletion mutations (indels) across the 96 replicates. This equates to a base-substitution mutation rate of 2.00 × 10(-10) mutations per site per generation, similar to that reported for the distantly related budding yeast Saccharomyces cerevisiae. However, these two yeast species differ dramatically in their spectrum of base substitutions, the types of indels (S. pombe is more prone to insertions), and the pattern of selection required to counteract a strong AT-biased mutation rate. Overall, our results indicate that GC-biased gene conversion does not play a major role in shaping the nucleotide composition of the S. pombe genome and suggest that the mechanisms of DNA maintenance may have diverged significantly between fission and budding yeasts. Unexpectedly, CpG sites appear to be excessively liable to mutation in both species despite the likely absence of DNA methylation.
Gregor Mendel Institute of Molecular Plant Biology, 1030 Vienna, Austria Institute of Population Genetics, 1210 Vetmeduni Vienna, Austria ashley.farlow@gmail.com milynch@indiana.edu.
Ashley
A
Farlow
Department of Biology, Indiana University, Bloomington, Indiana 47405.
Hongan
H
Long
Gregor Mendel Institute of Molecular Plant Biology, 1030 Vienna, Austria.
Stéphanie
S
Arnoux
Department of Biology, Indiana University, Bloomington, Indiana 47405.
Way
W
Sung
Department of Biology, Indiana University, Bloomington, Indiana 47405 School of Informatics and Computing, Indiana University, Bloomington, Indiana 47405.
Thomas G
TG
Doak
Gregor Mendel Institute of Molecular Plant Biology, 1030 Vienna, Austria.
Magnus
M
Nordborg
Department of Biology, Indiana University, Bloomington, Indiana 47405 ashley.farlow@gmail.com milynch@indiana.edu.
Michael
M
Lynch
D000595:Amino Acid Sequence / Q000235:genetics; D004247:DNA / Q000235:genetics*; D015966:Gene Expression Regulation, Fungal; D006238:Haploidy; D054643:INDEL Mutation / Q000235:genetics; D009154:Mutation / Q000235:genetics; D059645:Mutation Rate; D012441:Saccharomyces cerevisiae / Q000235:genetics*; D012568:Schizosaccharomyces / Q000235:genetics*
D004247:DNA
biased gene conversion; effective population size; fission yeast; mutation accumulation