Electric field-mediated BrUTP uptake by mouse oocytes, eggs, and embryos

Electropermeabilization was used to introduce 5-bromouridine 5'-triphosphate (BrUTP) into mouse oocytes, zygotes, 2-cell embryos, and parthenogenetic eggs containing nuclei transferred from 3T3 cells. BrUTP incorporated into nascent RNA was detected by indirect immunofluorescence. Two electric pulses of 100 micros duration and of 20 V strength applied at 10 mM concentration of BrUTP loaded most efficiently all cell types tested. Zygotes loaded with BrUTP developed for the next 20 hr in vitro and cleaved to 2-cell stage. The parameters of electric field which promoted BrUTP uptake were also efficient in inducing fusion of blastomeres of 2-cell embryos.