Efficient in vitro production of porcine blastocysts by handmade cloning with a combined electrical and chemical activation

Theriogenology. 2005 Oct 15;64(7):1536-45. doi: 10.1016/j.theriogenology.2005.03.021.

Abstract

The purpose of our work was to establish an efficient protocol for activation of porcine cytoplast-fibroblast constructs produced by the handmade cloning technique. Firstly, we investigated a combined electrical and chemical activation protocol for parthenogenetic development of in vitro matured zona-free oocytes. Oocytes were activated by one 80 micros pulse and subsequently cultured in cytochalasin B and cycloheximide. Developmental rates of blastocysts from activated oocytes were 49+/-1 and 40+/-2%, when using one 80 micros pulse of 0.85 or 1.25 kV/cm, respectively. The activation procedure was further confirmed by a simultaneous re-fusion and activation of bisected oocytes, resulting in a blastocyst rate of 41+/-8%. Secondly, the activation protocol was applied in the handmade cloning technique. In vitro matured zona-free porcine oocytes were bisected and halves containing no chromatin, i.e. the cytoplasts, were selected. Reconstructed embryos were produced by a two-step fusion procedure. At the first step, one cytoplast was fused to one fibroblast by one 80 micros pulse of 1.25 kV/cm. After 1h, the cytoplast-fibroblast pair and another cytoplast were fused and activated simultaneously by one 80 micros pulse of 0.85 kV/cm, and subsequently cultured in cytochalasin B and cycloheximide. The development of reconstructed embryos to the blastocyst stage was in average 21+/-4%, and total blastocyst cell counts were in average 48+/-3. Thus, the combined electrical and chemical activation procedure resulted in efficient blastocyst development in the handmade cloning technique.

MeSH terms

  • Animals
  • Blastocyst*
  • Cloning, Organism / methods
  • Cloning, Organism / veterinary*
  • Cycloheximide / administration & dosage
  • Cytochalasin B / administration & dosage
  • Electric Stimulation
  • Female
  • Oocytes / physiology*
  • Swine / embryology*

Substances

  • Cytochalasin B
  • Cycloheximide