The aim of this study was to compare the quality of rabbit transgenic embryos obtained upon microinjection of gene constructs containing different promoters and green fluorescent proteins (CMVIE–EGFP, PGK–EGFP and CMVIE–hrGFP). Developmental rate, total cell number in hatching blastocyst stage, number of apoptotic cells, diameter of embryos, transgene integration and transgenic mosaicism were investigated.
The rate of rabbit embryos microinjected with the different gene constructs developed up to morula stage was significantly lower (p < 0.05) than that of intact (non-microinjected) rabbit embryos (66–74vs. 98%). The highest efficiency of transgene integration (15%) was found when the CMVIE–EGFP (DrdI) gene construct was used, however a significantly higher transgenic mosaicism (60%) was found in rabbit embryos using this gene. The lowest cell number was counted in rabbit transgenic embryos with CMVIE–rhGFP linearized by ScaI (115.0 ± 8.20), the highest cell number (134.0 ± 35.00) was detected in rabbit transgenic embryos carrying PGK–EGFP (Not I) gene. The highest number of apoptotic cells (2.6 ± 0.33) was recorded in rabbit transgenic embryos with the integrated CMVIE–EGFP (ClaI) transgene.
Based on these results a more suitable gene marker for rabbit transgenic embryos production and selection is the CMVIE–EGFP (ClaI) gene construct. Prior to using microinjected embryos (for embryo transfer, vitrification or ESC isolation) it is necessary to pre-select microinjected embryos with evident transgenic mosaicism.