Inter-Individual Variation in DNA Methylation Patterns across Two Tissues and Leukocytes in Mature Brahman Cattle

Area of Science:

• Epigenetics
• Animal Genomics
• Developmental Biology

Background:

• Inter-individual variation in DNA methylation is crucial for understanding phenotypic variation and environmental influences.
• Previous research has not quantified DNA methylation variability in female cattle or the impact of prenatal stressors.

Purpose of the Study:

• To quantify inter-individual DNA methylation variation in mature Brahman females.
• To assess the effect of prenatal stress on DNA methylation variability.

Main Methods:

• Pregnant Brahman cows underwent prenatal transport stress at specific gestation points; controls were non-transported.
• DNA methylation was analyzed in leukocytes, amygdala, and anterior pituitary glands from offspring at 5 years of age.
• Variable cytosine-phosphate-guanine (mCpG) sites were identified and associated with genomic features.

Main Results:

• The anterior pituitary gland exhibited the highest DNA methylation variability (mCpG sites), while the amygdala showed the least.
• Variable mCpG sites were frequently linked to retrotransposable elements and repetitive genomic regions.
• Genomic features with high methylation variation were involved in immune responses, signaling, and metabolic processes.
• Tissue-specific variability was observed, with limited overlap between tissues and leukocytes, supporting tissue-specific gene regulation.
• While many variable CpG sites were shared between prenatal stress (PNS) and control groups within tissues, genomic feature overlap was minimal.

Conclusions:

• The anterior pituitary gland is a key tissue for studying DNA methylation variability in cattle.
• Prenatal stress did not significantly alter the overall patterns of DNA methylation variability, but influenced the location of these variations.
• The interaction between the prenatal environment and the genome likely dictates the tissue-specific distribution of variable DNA methylation.