Efficient TALEN-mediated gene targeting of chicken primordial germ cells

In this work we use TALE nucleases (TALENs) to target a reporter construct to the <i>DDX4</i> (<i>vasa</i>) locus in chicken primordial germ cells (PGCs). Vasa is a key germ cell determinant in many animal species and is posited to control avian germ cell formation. We show that TALENs mediate homology-directed repair of the <i>DDX4</i> locus on the Z sex chromosome at high (8.1%) efficiencies. Large genetic deletions of 30 kb encompassing the entire <i>DDX4</i> locus were also created using a single TALEN pair. The targeted PGCs were germline competent and were used to produce <i>DDX4</i> null offspring. In <i>DDX4</i> knockout chickens, PGCs are initially formed but are lost during meiosis in the developing ovary, leading to adult female sterility. TALEN-mediated gene targeting in avian PGCs is therefore an efficient process.