Nuclear transfer system for the direct induction of embryonic transcripts from intra- and cross-species nuclei using mouse 4-cell embryos.

Reprogramming of somatic nuclei toward the embryonic state has been studied using nuclear transfer (NT) to an oocyte at the metaphase II (MII) stage. In this NT, a somatic nucleus transplanted into an MII oocyte of the same species undergoes DNA replication and cell division before activating embryonic genes. Here, we describe a direct NT protocol using 4-cell stage mouse embryos that enables reprogramming of intra- and cross-species nuclei to express embryonic genes without requiring DNA replication and cell division. For complete details on the use and execution of this protocol, please refer to Tomikawa et al. (2021).