Generation of live mice from haploid ESCs with germline-DMR deletions or switch.

Genomic imprinting is required for sexual reproduction and embryonic development of mammals, in which, differentially methylated regions (DMRs) regulate the parent-specific monoallelic expression of imprinted genes. Numerous studies on imprinted genes have highlighted their critical roles in development. However, what imprinting network is essential for development is still unclear.

CRISPR-Cas9-mediated genome editing in one blastomere of two-cell embryos reveals a novel Tet3 function in regulating neocortical development.

Studying the early function of essential genes is an important and challenging problem in developmental biology. Here, we established a method for rapidly inducing CRISPR-Cas9-mediated mutations in one blastomere of two-cell stage embryos, termed 2-cell embryo-CRISPR-Cas9 injection (2CC), to study the in vivo function of essential (or unknown) genes in founder chimeric mice. By injecting both Cre mRNA and CRISPR-Cas9 targeting the gene of interest into fluorescent reporter mice, the 2CC method can trace both wild-type and mutant cells at different developmental stages, offering internal control for phenotypic analyses of mutant cells.