Location: Livestock Bio-SystemsTitle: Abundance of total genomic 5-methylcytosine and 5-hydroxymethylcytosine in different pig tissues
Submitted to: Journal of Animal Science Supplement
Publication Type: Abstract Only
Publication Acceptance Date: 3/2/2013
Publication Date: 7/8/2013
Citation: Freking, B.A., Nonneman, D.J. 2013. Abundance of total genomic 5-methylcytosine and 5-hydroxymethylcytosine in different pig tissues. Journal of Animal Science. 91 (E-Supplement 2):537 (Abstract #TH185).
Technical Abstract: Methylation of genomic DNA is essential in regulating gene expression in many biological processes including reproduction, development, and growth. Cytosine residues in mammalian genomes are enzymatically modified to 5-methylcytosine (5MC), which participates in transcriptional regulation of genes. The 5MC modified base can be further enzymatically altered to 5-hydroxymethylcytosine (5hMC) by the TET family of methylcytosine dioxygenases. The function of 5hMC in gene regulation is not clear. Because these two modifications are indistinguishable by traditional sequencing methods even when supplemented by bisulfite conversion, analysis of 5MC and 5hMC is confounded using that approach. Our objective was to quantify the abundance of both modified bases in several porcine tissues using a colorimetric immunoassay specific for each modification. The content of 5MC or 5hMC DNA was quantified using a commercially available kit according to the manufacturer’s instructions. Eight mature pregnant females (4 multi-parous Meishan, 4 primiparous white composite) were sampled for 11 different tissues at critical periods during gestation to contribute fetal tissues for a separate study. Tissues included brain, endometrium, heart, small intestine, kidney, muscle, liver, lung, ovary, pancreas, and uterus. Data were analyzed by mixed-model ANOVA procedures fitting breed and tissue as fixed effects and gilt as a random effect. Breed was not significant for any of the variables tested so data are presented by tissue across breeds as a percentage of total DNA. Values for 5MC ranged from 1.25 ± 0.26% for pancreas to 5.68 ± 0.26% for small intestine. Values for 5hMC ranged from 0.006 ± 0.014% for pancreas to 0.294 ± 0.014% for brain. These data indicated a higher abundance of 5hMC and a higher ratio of 5hMC to 5MC in brain tissue (1.7-fold) compared to all other tissues examined, perhaps indicating a greater role of this modified base in tissues of the central nervous system. USDA is an equal opportunity provider and employer.