Production of large, defined genome modifications in rats by targeting rat embryonic stem cells.

Rats were more frequently used than mice to model human disease before mouse embryonic stem cells (mESCs) revolutionized genetic engineering in mice. Rat ESCs (rESCs) were first reported over 10 years ago, yet they are not as frequently used as mESCs. CRISPR-based gene editing in zygotes is widely used in rats but is limited by the difficulty of inserting or replacing DNA sequences larger than about 10 kb.

Kappa-on-Heavy (KoH) bodies are a distinct class of fully-human antibody-like therapeutic agents with antigen-binding properties.

We describe a Kappa-on-Heavy (KoH) mouse that produces a class of highly diverse, fully human, antibody-like agents. This mouse was made by replacing the germline variable sequences of both the Ig heavy-chain (IgH) and Ig kappa (IgK) loci with the human IgK germline variable sequences, producing antibody-like molecules with an antigen binding site made up of 2 kappa variable domains. These molecules, named KoH bodies, structurally mimic naturally existing Bence-Jones light-chain dimers in their variable domains and remain wild-type in their antibody constant domains.

Deletion of Adam6 in Mus musculus leads to male subfertility and deficits in sperm ascent into the oviduct.

The Adisintegrin and metalloprotease domain-containing (ADAM) family of proteins is involved in cell adhesion, migration, proteolysis, and signaling. Many ADAMs are required for reproduction; however, the role of Adam6 has remained largely unknown. In the course of humanizing the mouse immunoglobulin heavy chain (IgH) locus, we generated Adam6-deficient mice that demonstrate severe subfertility.

Injecting Embryonic Stem Cells into Eight-Cell-Stage Mouse Embryos.

In this protocol, eight-cell-stage precompaction embryos from outbred mouse strains are used for the injection of hybrid or inbred embryonic stem (ES) cells. This process often leads to generation of fully ES cell-derived so-called F mice (VelociMice). Postinjection culture of embryos is necessary to achieve the highest ratio of fully ES cell-derived mice and high-degree chimeras.