Epigenetics

Epigenetic Modifications in the Longissimus dorsi Muscle of Piglets Exposed to In Utero Heat Stress

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Abstract

Heat stress (HS) is a significant challenge affecting the health, physiology, and productivity of pigs. Due to their limited heat dissipation capacity and inefficient thermoregulation, pigs are particularly vulnerable to high ambient temperatures, which can lead to substantial economic losses and welfare issues. Furthermore, in utero heat stress (IUHS) has been shown to induce long-term alterations in offspring physiology, behavior, and metabolism, and epigenetic mechanisms could mediate these persistent effects. Specifically, DNA methylation is among the most stable and heritable epigenetic modifications, regulating gene expression without altering the DNA sequence. Therefore, the objectives of this study were to 1) investigate how prenatal thermal environments influence DNA methylation patterns in utero thermoneutral (IUTN) and IUHS pigs, and 2) detect differentially methylated loci (DML) and regions (DMR) based on whole-genome bisulfite sequencing (WGBS) data. Pregnant gilts (Large White x Landrace) were exposed to thermoneutral (TN; n = 10; 17.5 ± 2.1 °C) or cyclic heat stress (HS; n = 10; 26-36 °C) conditions from d 0-59 of gestation. Thereafter, all animals were maintained under TN conditions (20.9 ± 2.3 °C) for the remainder of gestation, post-weaning, and until 105 days of age when 20 piglets (10 TN, 10 HS) were euthanized, and Longissimus dorsi were collected for WGBS analysis. Both females and males were included. The libraries were sequenced on Illumina platforms. Read quality control and adapter trimming were performed using Trim Galore. Following genome preparation, the high-quality reads were aligned to the Sus scrofa reference genome (Sscrofa11.1) using Bismark and Bowtie2. Subsequent steps included deduplication and methylation extraction according to the Bismark workflow. Differentially methylated loci and DMR were identified using the R package methylKit. After applying a minimum read coverage threshold of 10à— and filtering for autosomal CpG, 11,232 cytosines were retained. In total, 100 DML and 461 DMR were detected between IUHS and IUTN samples (FDR CNOT6L (RNA degradation and miRNA stability), CD84 (immune activation), SMPD3 (ceramide-mediated apoptosis and stress signaling), and OSBPL8 (lipid metabolism). DMR included ARID1B, involved in adipogenesis and adipocyte differentiation, and DUSP4, which modulates corticosteroid sensitivity. In conclusion, these findings demonstrate that IUHS induces epigenetic alterations in skeletal muscle, potentially affecting metabolic, stress, and immune-related pathways, thereby contributing to a better understanding of the epigenomic mechanisms underlying the postnatal consequences of IUHS in pigs.

Keywords: 2026

How to Cite:

Durval, M., Johnson, J., Braz, C., Musa, J., Maskal, J. & Brito, L., (2026) “Epigenetic Modifications in the Longissimus dorsi Muscle of Piglets Exposed to In Utero Heat Stress”, World Congress on Genetics Applied to Livestock Production Digital Archive 2026(1): 2286764. doi: https://doi.org/10.31274/wcgalp.24113

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