Simple assay method for endocrine disrupters by in vitro quail embryo culture: nonylphenol acts as a weak estrogen in quail embryos.

Many chemicals that are not structurally related to estrogen have estrogen-like activity. In this study, we tried to apply a quail embryo culture system for assessing the in vivo effects of such chemicals on the development of quail embryos. Beta-estradiol induced feminization of the gonads of genetically male embryos, which was confirmed by the increase in the size of the left gonad and female-specific aromatase expression, while male-specific SOX9 expression was not affected. Nonylphenol, which has a weak estrogenic activity, reduced the viability and body weight of embryos. Simultaneously, several genetically male embryos were feminized in terms of gonadal size and aromatase expression. These results indicate that the avian embryo culture system was useful for evaluating endocrine disrupters.

Production of chimeric monoclonal antibodies by genetically manipulated chickens.

Genetically manipulated chickens producing chimeric monoclonal antibodies were generated by injecting retroviral vectors encoding genes for the heavy and light chains of antibodies into developing embryos. The transgene was detected in all chickens that hatched, and they stably produced the chimeric antibodies in their serum. After sexual maturation, the antibodies were also produced in eggs laid by the manipulated hens. The stable antibody production was observed both in egg white and yolk throughout the breeding period. The chimeric antibodies produced by the chickens were properly assembled and exhibited antigen-binding activities. Furthermore, we characterized the structures of the N-linked oligosaccharide chains added to the Fc-region of the recombinant antibodies produced in the serum, egg white and yolk of the chickens.

High-level expression of single-chain Fv-Fc fusion protein in serum and egg white of genetically manipulated chickens by using a retroviral vector.

We report here the generation of transgenic chickens using a retroviral vector for the production of recombinant proteins. It was found that the transgene expression was suppressed when a Moloney murine leukemia virus-based retroviral vector was injected into chicken embryos at the blastodermal stage. When a concentrated viral solution was injected into the heart of developing embryos after 50 to 60 h of incubation, transgene expression was observed throughout the embryo, including the gonads. For practical production, a retroviral vector encoding an expression cassette of antiprion single-chain Fv fused with the Fc region of human immunoglobulin G1 (scFv-Fc) was injected into chicken embryos. The birds that hatched stably produced scFv-Fc in their serum and eggs at high levels (approximately 5.6 mg/ml). We obtained transgenic progeny from a transgenic chicken generated with this procedure. The transgene was stably integrated into the chromosomes of transgenic progeny. The transgenic progeny also expressed scFv-Fc in the serum and eggs.