Reproduction Abstracts

Epigenetic programming has a crucial role in mammalian development. It is well described that disarrangement of epigenetic programming is associated with impaired embryonic development, compromised pregnancy (ie. abortion or preeclampsia) and several imprinting disorders (i.e Prader Willi and Beckwith-Wiedemann syndromes). A useful tool to better understand the etiology of compromised pregnancy is represented by uniparental embryos, characterized by only maternal (parthenogenotes – PAR) or only paternal (androgenotes – AND) genome, not compatible with full-term development. To this aim, we in vitro produced uniparental (AND, PAR) and biparental (in vitro fertilized Control – CTR) sheep embryos, transferred blastocyst stage embryos in recipient female and subsequently collected early placenta tissues at 20 day of pregnancy. Subsequently, we evaluated by qPCR 1) the expression of a selected panel of maternally (H19, IGF2R) and paternally (IGF2, MEST, DLK1) expressed imprinted genes and 2) the expression of the main enzymes involved in DNA methylation maintenance (DNMT1) and de novo methylation (DNMT3A, DNMT3B). Our data revealed that imprinted genes were expressed according to uniparental genomic composition (only maternal – PAR, only paternal AND). Moreover we observed that DNMTs mRNA levels were mainly upregulated in PAR placenta (P<0.05) compared to AND and CTR ones. Taken together, these results revealed that the parental specific expression of the analyzed imprinted genes is maintained in sheep placenta and suggested a possible rescue mechanism to correct improper epigenetic programming in PAR tissues but not in AND one, probably because at day 20 of pregnancy they are severely compromised and failed further development.