Dalyn Davis, Lant Jenkins

Currently, nematodes, fruit flies, and zebrafish are effective models for gene manipulation. Avian models have served as embryonic models and have historically proved to be powerful in exploring developmental processes such as neural tube or limb development. Because of high chick fecundity, a relatively short period of development, and the accessibility of the chick embryo, the development of chick models is ideal for gene manipulation and would allow for an increased ability to study the relationship between genes and phenotypes. However, the inability to access single cell zygotes has led to an inability to derive stem cells that contribute to the germ line. As part of a larger project to develop the chick as a model for ontogeny, we are designing drug inducible, lineage traceable DNA constructs that we will introduce to the germ line of chickens. Briefly, these constructs are first introduced into chicken primordial germ cells (cPGCs). The genetically modified cPGCs are injected into chick embryos where they colonize the gonad of the embryo. These embryos are allowed to develop, hatch, and grow to adulthood where they can pass on genetic constructs to progeny. In transgenic progeny, we can activate the expression of transgenes through injection of a drug whenever or wherever we desire to examine the consequences of aberrant gene activity in an otherwise normal embryo. We have generated constructs that through the introduction of a drug activate or inactivate important developmental pathways and express green fluorescent protein (GFP). Therefore, we are able to examine the fates of cells subjected to abnormal signaling at any given time or place in development. We anticipate that the development of these powerful genetic tools will be of broad interest to the scientific community.