Impact of embryonic expression of enhanced green fluorescent protein on early mouse development

Abstract

The impact of embryonic enhanced green fluorescent protein (EGFP)-expression on development is not clear. In this study, we comprehensively assessed EGFP-expression pattern and its effect on early mouse development, following pronuclear-microinjection of the EGFP-transgene, containing chicken-β-actin promoter and cytomegalovirus enhancer. Preimplantation embryos exhibited differential EGFP-expression patterns. While blastocyst development of non-expressing embryos was 77.3 ± 1.8%, that of expressing embryos was only 43.9 ± 1.6% (P<0.0001). Developmental competence of embryos negatively correlated (r=−0.99) with the levels of EGFP-expression. Faint-, moderate-, and intense-expressing embryos developed to 83.1 ± 5.3%, 50 ± 5%, and 9.5 ± 3.9% blastocysts, respectively (P<0.002). Interestingly, blastocysts expressing faint-moderate levels of EGFP were developmentally competent through the post-implantation period and delivered viable transgenic 'green' mice, following embryo transfer. These results indicate that hyper-expression of EGFP affects preimplantation development and faint-moderate level of its expression is compatible with normal embryogenesis in the mouse.