title: Developmental and epigenetic anomalies in cloned cattle.
abstract: Many of the developmental anomalies observed in cloned animals are related to foetal and placental overgrowth, a phenomenon known as the 'large offspring syndrome' (LOS) in ruminants. It has been hypothesized that the epigenetic control of imprinted genes, that is, genes that are expressed in a parental-specific manner, is at the root of LOS. Our recent research has focused on understanding epigenetic alterations to imprinted genes that are associated with assisted reproductive technologies (ART), such as early embryo in vitro culture (IVC) and somatic cell nuclear transfer (SCNT) in cattle. We have sought and identified single nucleotide polymorphisms in Bos indicus DNA useful for the analysis of parental-specific alleles and their respective transcripts in tissues from hybrid embryos derived by crossing Bos indicus and Bos taurus cattle. By analysing differentially methylated regions (DMRs) of imprinted genes SNRPN, H19 and the IGF2R in cattle, we demonstrated that there is a generalized hypomethylation of the imprinted allele and the biallelic expression of embryos produced by SCNT when compared to the methylation patterns observed in vivo (artificially inseminated). Together, these results indicate that imprinting marks are erased during the reprogramming of the somatic cell nucleus during early development, indicating that such epigenetic anomalies may play a key role in mortality and morbidity of cloned animals.
authors: Centre de Recherche en Reproduction Animale, Faculté de Médecine Vétérinaire, Université de Montréal, Saint-Hyacinthe, QC, Canada. smithl@medvet.umontreal.ca
authors: L C
authors: LC
authors: Smith
authors: J
authors: J
authors: Suzuki
authors: A K
authors: AK
authors: Goff
authors: F
authors: F
authors: Filion
authors: J
authors: J
authors: Therrien
authors: B D
authors: BD
authors: Murphy
authors: H R
authors: HR
authors: Kohan-Ghadr
authors: R
authors: R
authors: Lefebvre
authors: A C
authors: AC
authors: Brisville
authors: S
authors: S
authors: Buczinski
authors: G
authors: G
authors: Fecteau
authors: F
authors: F
authors: Perecin
authors: F V
authors: FV
authors: Meirelles
mesh_terms: D000818:Animals; D002417:Cattle / Q000002:abnormalities* / Q000235:genetics; D019976:Cloning, Organism / Q000009:adverse effects / Q000662:veterinary*; D044127:Epigenesis, Genetic / Q000235:genetics*; D005260:Female; D018507:Gene Expression Regulation, Developmental / Q000502:physiology*; D011247:Pregnancy