Impact of seasonality and storage of semen on epigenetics in swine placenta and fetal livers

Authors: Rempel, Lea; KRAUTKRAMER, M - University Of Wisconsin; PARRISH, J - University Of Wisconsin; Miles, Jeremy

Submitted to: Society for the Study of Reproduction Annual Meeting
Publication Type: Abstract Only
Publication Acceptance Date: 5/1/2018
Publication Date: 7/10/2018
Citation: Rempel, L.A., Krautkramer, M.M., Parrish, J.J., Miles, J.R. 2018. Impact of seasonality and storage of semen on epigenetics in swine placenta and fetal livers [abstract]. In proceedings: Society for the Study of Reproduction 51st Annual Meeting, 10-13 July 2018, New Orleans, LA. p. 27-28. Available: https://www.ssr.org/sites/ssr.org/files/2018_annual_meeting_abstracts_updated.pdf

Interpretive Summary:

Technical Abstract: Epigenetics includes the study of external factors that can influence the expression of genes by altering accessibility of DNA through methylation and histone modification. To investigate the influence of: season (semen collection and breeding), absolute sperm head-shape change, and semen storage on placental and fetal tissues (45d gestation); 83 pregnancies (n =< 5 litters per group) generated in the summer or winter using boar semen from either least or most sperm head-shape change between June and August, collected during cool or warm seasons and stored either as cooled-extended or cryopreserved. Correlation of methylation activity within tissues were assessed with relative quantitative expression of candidate genes with differentially methylated regions using Pearson’s Correlation. Effects upon relative expression were evaluated using the Mixed procedure of SAS. Ratio of 5-methylcytosine to 5-hydroxymethylcytosine activity (5mC:5hmC) was lower (P < 0.05) in placental tissue versus fetal liver. Within tissue, fetal liver had a lower (P < 0.05) ratio from summer matings, while placental tissues were least (P < 0.05) during winter matings. There was a negative (P < 0.05) relationship between 5mC:5hmC and placental relative expression of CDH1 (-0.17) and GNAS (-0.30). No correlations were detected between 5mC:5hmC and fetal liver relative expression. Relative expression of CDH1 tended (P < 0.10) to be greater in placenta generated from cryopreserved semen versus cooled-extended semen and tended (P < 0.10) to be greater in pregnancies from semen collected during cool periods versus warm periods. Relative expression of placental GNAS was greatest (P < 0.05) in pregnancies derived from semen collected during cool periods used in winter matings, least (P < 0.05) from semen collected during cool periods used in summer matings, and intermediate from semen collected during warm seasons regardless of mating season. Cryopreserved semen yielded greater (P < 0.05) placental relative expression of GNAS. Placental MEST and RHOBTB3 tended (P < 0.10) to have greater relative expression from pregnancies generated using semen collected during cool periods used during winter matings. Relative expression of GNAS and HGF within fetal liver was greater (P < 0.05) from pregnancies generated from winter matings. Pregnancies generated from semen with the least amount of sperm head-shape change and winter matings had the greatest (P < 0.05) relative expression of fetal liver CDH1, those derived from semen with most head-shape change and winter matings were intermediate, and relative expression of fetal liver CDH1, was least (P < 0.05) from summer matings, regardless of sperm head-shape change. A lower 5mC:5hmC suggests increased gene transcript activity and was apparent in the current study within placental tissues. Seasonality of; semen collection, mating, and effect on sperm head-shape change had an influence on expression of genes with known differentially methylated regions from embryonic and extraembryonic tissues. To increase our understanding of external influences on epigenetics of the placenta, future studies will examine the seasonal effects of semen collection, storage, and mating on gene expression within epigenetic chromatin enzymes modification network.