An inducible germ cell ablation chicken model for high-grade germline chimeras

Chicken embryos are a powerful and widely used animal model in developmental biology studies. After the development of CRISPR technology, gene-edited chickens have been generated by transferring primordial germ cells (PGCs) after genetic modifications. However, the low inheritance caused by the competition between host germ cells and the transferred ones is the most common complication and largely reduces the production efficiency in this way. Here, we generated a gene-edited chicken, in which germ cells can be ablated in a drug-dependent manner, as recipients for gene-edited PGC transfer. We used the nitroreductase/metronidazole (NTR/Mtz) system for cell ablation, in which NTR produces cytotoxic alkylating agents from administered Mtz, causing cell apoptosis. The chicken Vasa homolog (CVH) gene locus is used to drive the expression of the NTR gene in a germ cell-specific manner. In addition, a fluorescent protein gene, mCherry, was also placed in the CVH locus to visualize the PGCs. We named this system germ cell-Specific AutonoMoUs RemovAl Induction (gSAMURAI). gSAMURAI chickens will be an ideal recipient to produce offspring derived from transplanted exogenous germ cells.