Biological differences between in vitro produced bovine embryos and parthenotes

Abstract

Parthenotes may represent an alternate ethical source of stem cells, once biological differences between parthenotes and embryos can be understood. In this study, we analyzed development, trophectoderm (TE) differentiation, apoptosis/necrosis, and ploidy in parthenotes andin vitroproduced bovine embryos. Subsequently, using real-time PCR, we analyzed the expression of genes expected to underlie the observed differences at the blastocyst stage.In vitromatured oocytes were either fertilized or activated with ionomycin +6-DMAP and cultured in simple medium. Parthenotes showed enhanced blastocyst development and diploidy and reduced TE cell counts. Apoptotic and necrotic indexes did not vary, but parthenotes evidenced a higher relative proportion of apoptotic cells between inner cell mass and TE. The pluripotence-relatedPOU5F1and the methylationDNMT3Agenes were downregulated in parthenotes. Among pregnancy recognition genes,TP-1was upregulated in parthenotes, whilePGRMC1andPLAC8did not change. Expression ofp66shcandBAX/BCL2ratio were higher, andp53lower, in parthenotes. Among metabolism genes,SLC2A1was downregulated, whileAKR1B1,PTGS2,H6PD, andTXNwere upregulated in parthenotes, andSLC2A5did not differ. Among genes involved in compaction/blastulation,GJA1was downregulated in parthenotes, but no differences were detected withinATP1A1andCDH1. Within parthenotes, the expression levels ofSLC2A1,TP-1, andH6PD, and possiblyAKR1B1, resemble patterns described in female embryos. The pro-apoptotic profile is more pronounced in parthenotes than in embryos, which may differ in their way to channel apoptotic stimuli, throughp66shcandp53respectively, and in their mechanisms to control pluripotency andde novomethylation.