Are you tired of the same old chicken dish day in and day out? Well, new chicken chimeras may one day get you over your chicken blues. A chimera is either an organism, organ or organ part that consists of two or more tissues with different genetic compositions. It can be produced either by organ transplantation, grafting or, in the case of the present study, genetic engineering. But while mutagenesis and transgenic techniques have become routine in animals such as mice, zebrafish and cattle, this process is technically challenging in avian species, despite the many potential advantages in using avian embryos to study development and physiological systems. In the present study published by Yongmei Xi, Masa-Aki Hattori and colleagues, they used a novel approach to create an avian chimera: the peafowl–chicken.
Hattori and colleagues incorporated a green fluorescent protein (GFP) into peafowl cells so that they glowed green and could be easily traced during migration through chicken tissues. The GFP-expressing peafowl cells were then mixed and fused by electroporation to isolated white leghorn chicken blastodermal cells, which are tiny reproductive cells from which the chicken embryo develops. The now fused peafowl–chicken cells were subsequently injected into freshly laid, fertile white leghorn chicken eggs, and the manipulated chicken eggs sealed with parafilm and allowed to develop at 37.6°C.
The team analyzed the contribution of the peafowl cells to the embryonic development of the chicken by tracing the migration of cells carrying the marker GFP genes in the developing chimeric embryo. By sampling the injected embryos at different stages of development and observing the tissue under a fluorescent microscope, they discovered that they had successfully produced a chimeric embryo. They found glowing green patches of peafowl cells in several different embryonic locations, including the head, gonad, heart and ectoderm. And Hattori's team also characterised the embryo samples with PCR, using primers for specific genetic markers and the GFP gene, confirming the presence of peafowl cells in the developing embryo. This analysis revealed that the peafowl cells were indeed present throughout the chicken's embryonic tissues. The team had successfully produced a peafowl–chicken chimeric embryo.
While there is potential for the incorporated peafowl cells to participate in the development of the chicken embryo, future studies are necessary to determine the long-term survival of these embryos and the functionality of the grafts. However, this study does describe a novel approach for chimera construction and tracking embryonic development. The development of unique chimeras could potentially lead to interesting new model systems for the study of disease and many physiological processes. And as for our diet:peafowl–chicken Kiev, anyone?