Naive pluripotency is associated with global DNA hypomethylation

Naive pluripotent embryonic stem cells (ESCs) and embryonic germ cells (EGCs) are derived from the preimplantation epiblast and primordial germ cells (PGCs), respectively. We investigated whether differences exist between ESCs and EGCs, in view of their distinct developmental origins. PGCs are programmed to undergo global DNA demethylation; however, we find that EGCs and ESCs exhibit equivalent global DNA methylation levels. Inhibition of MEK and Gsk3b by 2i conditions leads to pronounced reduction in DNA methylation in both cell types. This is driven by Prdm14 and is associated with downregulation of Dnmt3a and Dnmt3b. However, genomic imprints are maintained in 2i, and we report derivation of EGCs with intact genomic imprints. Collectively, our findings establish that culture in 2i instills a naive pluripotent state with a distinctive epigenetic configuration that parallels molecular features observed in both the preimplantation epiblast and nascent PGCs.

A new syndrome with prenatally diagnosed thoracoschisis, hiatal hernia and extremities' agenesis: case report

Thoracoschisis is a very rare congenital anomaly and is usually associated with limb and abdominal wall defects forming part of limb-body wall complex. We here present a case of a 29-week-4-day pregnancy ended with intrauterine demise. Postmortem examination revealed hiatal hernia, thoracoschisis and protrusion of some part of liver from this defect, left forearm agenesis and right arm and right hand agenesis. The findings accompanying thoracoschisis in this presented case exclude any previously reported related syndrome and we believe that this is a new syndrome.