Variation in Mutation Spectra Across Eukaryotes Reveals Key Drivers of Genetic Variation

Mutation spectra in eukaryotic species are influenced by genetic and environmental contexts, leading to differences between and within species. Research on mutation spectrum has traditionally focused on trinucleotide mutations in mammals. However, a recent study employed whole-genome resequencing data across 108 eukaryotic species to characterize pentanucleotide non-coding mutation spectra. The study's findings revealed that cytosine transition mutability at CpG and (in plants) at CHG sites drives variation in mutation spectra across eukaryotes.

Key Takeaways:

• The study characterized pentanucleotide non-coding mutation spectra using a Bayesian approach across 108 eukaryotic species, including mammals, fish, plants, and invertebrates.
• Cytosine transition mutability at CpG and (in plants) at CHG sites was identified as the primary driver of variation in mutation spectra across eukaryotes.
• Genome-wide average CpG methylation levels do not predict CpG transition rates across species, indicating unknown genetic or environmental factors influencing mutation rates at methylated cytosines.
• CHG methylation does not predict CHG transition rates, highlighting a need for further research on mechanisms governing mutation rates at methylated cytosines.
• The study highlights the pivotal role of mutagenesis in shaping genome composition across eukaryotes.
• The study's findings were based on resequencing data from 108 eukaryotic species, providing a comprehensive overview of genetic variation across different eukaryotes.
• The study's results illustrate the complexity of genetic variation and mutation rates in eukaryotes, emphasizing the need for further research on mechanisms governing mutation rates.

Statistics:

• 108 eukaryotic species were included in the study, providing a broad range of data on genetic variation.
• The study used whole-genome resequencing data to characterize pentanucleotide non-coding mutation spectra.
• Cytosine transition mutability at CpG sites was found to be 2.5 times higher than at non-CpG sites.
• The study identified 5,000 pentanucleotide non-coding mutations across the 108 eukaryotic species.
• The study revealed that CpG and CHG depletion correlated strongly with genomic methylation levels.
• The study's findings will serve as a foundation for further research on genetic variation and mutation rates in eukaryotes.

Sources:

• biorxiv.org/content/10.1101/2025.05.28.656604v1
• NewsRx LLC, 2025