Abstract
We investigated translation kinetics after enhanced green fluorescent protein (EGFP) mRNA injection into maturing porcine oocytes and then established a method for selecting the oocytes that were translating the injected mRNA without fixing and staining. The EGFP signal was observed within 3 h of the mRNA injection, and the EGFP expression rate reached a maximum (about 30%) at 6 h after injection. The high EGFP expression rate increased gradually until 18 h after injection. In the EGFP expressing group, degenerated oocytes were absent and the maturation rate was comparable to that of non-injected oocytes, while the maturation rate was low and some oocytes were degenerated in the non-translating group. There were a significant number of morphologically normal oocytes without EGFP expression, therefore, we tried to select the oocytes translating the injected mRNA by co-injecting objective mRNA with EGFP mRNA as a marker. We found that the oocytes expressing EGFP also highly translated the co-injected mRNAs. These results suggest that translation of injected mRNA starts within 3 h and continues for 18 h after injection in maturing porcine oocytes, and that co-injection of objective mRNA with EGFP mRNA is a useful method for finding the oocytes that are translating objective mRNAs.
