Alterations in Body Composition and Transcriptional Profile as a Result of Prenatal Heat Stress Exposure in Pigs

Gestational development is environmentally influenced through multiple mechanisms.  We have previously demonstrated that gestational heat stress (HS) impacts future insulin regulation and body composition. To investigate this, we have conducted transcriptional profiling of liver, adipose tissue (AT), and longissimus dorsi (LD) of pigs exposed to HS in utero.  Forty-eight offspring from first parity crossbred gilts were exposed to one of four in utero environmental treatments (TNTN, TNHS, HSTN, or HSHS). TNTN and HSHS treatments were exposed to thermal neutral (TN) or heat stress (HS) conditions during the entire gestation, respectively.  HSTN and TNHS treatments were heat-stressed for the first or second half of gestation, respectively.  Offspring were later sacrificed at 14 and 19 weeks of age.  RNA-Seq was performed on 288 libraries.  In AT, liver, and LD, respectively, we identified 10.7, 15.2, and 11.1 million uniquely mappable reads per library and 20, 42, and 434 transcripts were identified as differentially expressed transcripts at 19 weeks of age. Methylation status for seven CpG positions upstream of MEF2A, a differentially expressed transcript in LD, were evaluated in the HSHS and TNTN treatments. A single CpG position was marginally correlated with transcript abundance.  In utero HS influenced postnatal gene expression in multiple tissues that may contribute to regulation of body composition.  This may occur through multiple mechanisms, such as modification of the methylome during cellular differentiation, which results in future alterations in transcriptional profile of specific tissues. This work was supported by USDA NIFA grant #2011-67003-30007.