Massive dysregulation of genes involved in cell signaling and placental development in cloned cattle conceptus and maternal endometrium.

A major unresolved issue in the cloning of mammals by somatic cell nuclear transfer (SCNT) is the mechanism by which the process fails after embryos are transferred to the uterus of recipients before or during the implantation window. We investigated this problem by using RNA sequencing (RNA-seq) to compare the transcriptomes in cattle conceptuses produced by SCNT and artificial insemination (AI) at day (d) 18 (preimplantation) and d 34 (postimplantation) of gestation. In addition, endometrium was profiled to identify the communication pathways that might be affected by the presence of a cloned conceptus, ultimately leading to mortality before or during the implantation window.

Spatial and temporal changes of decorin, type I collagen and fibronectin expression in normal and clone bovine placenta.

Introduction: Alteration of expression of various genes including extracellular matrix components, have been suggested to play major role in the placental pathologies after somatic cloning in mammals. The objectives of the present study were to analyze pattern of expression (mRNA and protein) of the small leucine-rich proteoglycan, Decorin in association with Type I Collagen and Fibronectin in bovine placental tissues from normal and clone pregnancies.

Methods: Genotyping and allelic expression of Decorin were determined by Sanger sequencing.

Captured retroviral envelope syncytin gene associated with the unique placental structure of higher ruminants.

Syncytins are envelope genes of retroviral origin that have been co-opted for a role in placentation and likely contribute to the remarkable diversity of placental structures. Independent capture events have been identified in primates, rodents, lagomorphs, and carnivores, where they are involved in the formation of a syncytium layer at the fetomaternal interface via trophoblast cell-cell fusion. We searched for similar genes within the suborder Ruminantia where the placenta lacks an extended syncytium layer but displays a heterologous cell-fusion process unique among eutherian mammals.

Review: Placental perturbations induce the developmental abnormalities often observed in bovine somatic cell nuclear transfer.

Since the first success in cloning sheep, the production of viable animals by somatic cell nuclear transfer (SCNT) has developed significantly. Cattle are by far the most successfully cloned species but, despite this, the technique is still associated with a high incidence of pregnancy failure and accompanying placental and fetal pathologies. Pre- and early post-implantation losses can affect up to 70% of the pregnancies.