Submitted to: International Society for Animal Genetics (ISAG)
Publication Type: Abstract Only
Publication Acceptance Date: 4/22/2016
Publication Date: 7/23/2016
Citation: Rempel, L.A., Miles, J.R. 2016. Impact of collection season and storage of semen on methylation activity in swine placental and fetal tissues derived from summer or winter breedings [abstract]. International Society for Animal Genetics (35th ISAG). Abstract Book. p. 44 (Abstract # P2013).
Technical Abstract: DNA methylation patterns in extra-embryonic tissues have been linked to irregular fetal growth and early pregnancy loss. The objective of the current study was to evaluate methylation profiles of placental and fetal tissue collected from pregnancies derived using cooled-extended (ExT) or cryopreserved (FrZ) semen from June (spring), August (summer), or January (winter) and breeding gilts in summer (August) or winter (January). Gilts were artificially inseminated 1x following synchronization in August or January with one of three semen types (August ExT or January ExT, August FrZ, and June FrZ) and a control group of females artificially inseminated following natural heat detection and 2x insemination with ExT semen. Gilts were harvested at approximately 45 d post-breeding. A portion of fetal liver and companion placenta were collected from the smallest, an average, and largest live piglet from each litter. Methylation (5-methylcytosine; 5mC) and hydroxymethylation (5-hydroxymethylcytosine; 5hmC) activity in fetal liver and placenta was measured to estimate gene transcription activity. Fetal liver 5mC activity was greater (P = 0.0472) from pregnancies derived using semen collected during cooler periods in comparison to semen from summer (8.0 % ± 0.51 and 6.7 % ± 0.56, respectively). No differences (P >= 0.1363) were detected within fetal liver for 5hmC activity. Fetal livers had decreased (P = 0.0058) 5mC:5hmC, and therefore increased gene transcription activity, when derived from summer breedings versus winter breedings (8.8 ± 2.54 and 19.9 ± 2.69, respectively). Placental 5mC activity was effected by breeding season with summer breedings less (P = 0.0383) than winter breedings (6.3 % ± 0.51 and 7.7 % ± 0.51, respectively) and semen collection period tended (P = 0.0762) to be greater from summer versus cooler collections (6.6 % ± 0.66 and 5.0 % ± 0.58, respectively). Placental 5hmC activity was also less (P = 0.0013) from summer matings in comparison to winter matings (4.3 % ± 0.62 and 7.3 % ± 0.63, respectively). In contrast to liver ratios, placentas derived from summer breedings had increased 5mC:5hmC versus winter breedings (4.2 ± 0.67 and 0.9 ± 0.67, respectively). The findings in the current study support the occurrence of male and female factors contributing to seasonal differences in methylation activity. However, breeding season of the gilt, summer or winter, may still harbor the greatest influence on transcriptional activity in fetal liver and placenta as measured by reduced ratio of 5mC to 5hmC.