In search of epigenetic marks in testes and sperm cells of differentially fed boars [RNA-Seq]
We investigated the nutritional effects on gene expression in sperm cells of F0 boars from a three generation Large White pig feeding experiment. A group of experimental (E) F0 boars were fed a standard diet supplemented with high amounts of methylating micronutrients whereas a control (C) group of F0 boars received a standard diet. These differentially fed F0 boars sired F1 boars which then sired 60 F2 pigs which were investigated in a previous study. The aim of this study was to investigate if the nutrition affects gene expression in sperm cells of differentially fed boars and thus carry information in the form of RNA molecules to the next generation. Four RNA samples from sperm cells of these differentially fed boars were analyzed by RNA-Seq methodology. We found no differential RNA expression in sperm cells of the two groups based on the adjusted P-value > 0.05. Nevertheless, we performed a pathway analysis with 105 genes that differed in gene expression on the level of nominal P-value < 0.05 between the two diet groups. We found a significant number of these differentially expressed genes were enriched for the pathway maps of bacterial infections in cystic fibrosis (CF) airways, glycolysis and gluconeogenesis p.3 and cell cycle_Initiation of mitosis. The GO processes including a significant portion of differentially expressed genes were viral transcription and viral genome expression, viral infectious cycle, cellular protein localization, cellular macromolecule localization, nuclear-transcribed mRNA catabolic process and nonsense-mediated decay. In summary, the results of the pathway analysis are also inconclusive and it is concluded that RNA expression in sperm cells is not significantly affected by extensive supplementation of methylating micronutrients. Consequently, RNA molecules could not be established as epigenetic marks in this feeding experiment. Overall design: Gene expression in sperm cells from differentially fed F0 boars was measured. F0 boars received either a standard diet or a standard diet supplemented with methylating micronutrients. These boars were used to study transgenerational epigenetic inheritance in a three generation pig pedigree. Therefore it was of interest if the diet affects gene expression in sperm cells which could then be transmitted to next generations.