Carry-over of mRNA during nuclear transfer in pigs

This research was designed to evaluate the changes that might occur to protein production after nuclear transfer. Eight-cell stage pig embryo nuclei were transferred to enucleated metaphase II oocytes. Twelve hours after nuclear transfer the nuclear transfer embryos were labeled with L-[35S] methionine and subjected to 1-dimensional polyacrylamide gel electrophoresis. During normal pig embryo development, embryonic RNA is produced by the 4-cell stage and results in the production of a 51 kDa band. This 51 kDa band persists through the 8-cell and compact morula stages. Eight-cell stage blastomeres of reconstituted embryos continued the production of the 51 kDa band even after treatment with alpha-amanitin. Since alpha-amanitin should block new mRNA synthesis, the production of this 51 kDa band is likely the result of a carry-over of mRNA coding for this protein in the blastomere cytoplasm.