title: Cobalamin supplementation during in vitro maturation improves developmental competence of sheep oocytes.
abstract: Pregnancies obtained by Assisted Reproductive Technologies are at higher risk of miscarriage than those obtained naturally. Previously, we reported impaired placental vascular development of in vitro produced (IVP) sheep embryos and defective DNA methylation in the placentae of those embryos. One reason behind these observed defects may be an impaired One Carbon Metabolism (OCM) The present study was performed to test the hypothesis that Cobalamin (Vitamin B12, an important OCM co-factor) supplementation during IVM corrects DNA methylation of IVP embryos and, consequently, ameliorates placental vasculogenesis. To this aim, embryos derived from oocytes matured with Cobalamin (B12 group) or without (negative control group, -CTR) were transferred to synchronized recipient sheep. At day 20 of pregnancy, collected embryos were morphologically evaluated while placentae were subjected to qPCR and histological analysis. The positive control group (+CTR) consisted of conceptuses obtained from naturally mated sheep. Results showed an increased fertilization rate in the B12 group vs -CTR (69.56% vs 57.91% respectively, P = 0.006) not associated with quantitative improvement in blastocyst and/or implantation rate (44.32% vs 36.67% respectively, P > 0.05). Moreover, Cobalamin supplementation during oocyte IVM ameliorated resulting conceptuses quality, in terms of placental vascularization (vessels' maturity and vasculogenetic factors' expression). The expression of DNA methyltransferases (DNMT1, DNMT3A and DNMT3B) was also improved in placentae from the B12 group. In conclusion, Cobalamin supplementation during oocyte IVM improves IVP embryo quality. These results suggest that Cobalamin should be included in standard IVM media.
authors.affiliation: Institute of Genetics and Animal Breeding, Polish Academy of Sciences, 05-552 Jastrzebiec, 36a Postepu str., Poland.
authors.forename: Federica
authors.initials: F
authors.lastname: Zacchini
authors.affiliation: Faculty of Veterinary Medicine, University of Teramo, via Renato Balzarini, 64100 Teramo, Italy.
authors.forename: Paola
authors.initials: P
authors.lastname: Toschi
authors.affiliation: Institute of Genetics and Animal Breeding, Polish Academy of Sciences, 05-552 Jastrzebiec, 36a Postepu str., Poland; National Research Institute of Animal Production, ul. Krakowska 1, 32-083 Balice n. Krakow, Poland. Electronic address: grazyna.ptak@izoo.krakow.pl.
authors.forename: Grazyna Ewa
authors.initials: GE
authors.lastname: Ptak
mesh_terms: D000818:Animals; D019175:DNA Methylation / Q000187:drug effects; D015254:DNA Modification Methylases / Q000235:genetics; D004624:Embryo Transfer / Q000662:veterinary; D004622:Embryo, Mammalian / Q000502:physiology; D047108:Embryonic Development / Q000187:drug effects; D005260:Female; D005307:Fertilization in Vitro / Q000662:veterinary; D015870:Gene Expression; D059471:In Vitro Oocyte Maturation Techniques / Q000379:methods / Q000662:veterinary*; D009865:Oocytes / Q000187:drug effects / Q000254:growth & development*; D010920:Placenta / Q000098:blood supply / Q000502:physiology; D011247:Pregnancy; D012756:Sheep / Q000196:embryology; D014805:Vitamin B 12 / Q000008:administration & dosage*
chemical_list: D015254:DNA Modification Methylases; D014805:Vitamin B 12
keywords: Cobalamin; DNA methylation; Oocyte; Placental vasculogenesis; Sheep