Effect of methylation on genome mutability in cattle

Area of Science:

• Genomics
• Evolutionary Biology
• Mammalian Genetics

Background:

• Germline de novo mutations (DNMs) are rare mammalian events influenced by factors like DNA methylation.
• Cattle's unique population structure offers a model to study mutational processes.
• Previous research indicates non-randomness in mutation rates.

Purpose of the Study:

• To investigate the mutational landscape in cattle using genomic data.
• To identify factors influencing germline mutation rates in cattle.
• To compare cattle mutation patterns with other mammalian species.

Main Methods:

• Analysis of de novo mutations (DNMs) in multigenerational cattle families (Holstein and Montbéliarde breeds).
• Detection of rare bi-allelic substitution variants in a large cohort of Holstein cattle.
• Utilizing identical-by-descent segments to track mutations across generations.

Main Results:

• Transitions were more frequent than transversions for both DNMs and rare substitutions.
• C>T substitutions were enriched at CpG sites, especially in low CpG density regions and correlated with methylation levels.
• Certain transposable elements, including young SINE and LINE elements, showed increased mutation rates.

Conclusions:

• The study provides a detailed view of the cattle mutational landscape.
• Findings reinforce known mutation patterns observed in other mammalian species.
• DNA methylation and transposable elements are significant factors in cattle germline mutation rates.