Development of Interspecies Somatic Cell Nuclear Transfer Embryos Reconstructed from Bactrian Camel (Camelus bactrianus) Fibroblasts and Dromedary Camel (Camelus dromedarius) Ooplasm.

Abstract

Interspecies somatic cell nucleus transfer could not only be a useful bioassay system for assessing the ability of mammalian somatic cells to develop into embryos but can also be used as a possible approach to conserve endangered species. It could provide a useful technique to preserve the wild Bactrian camels, which are threatened with extinction. In the present study embryos were reconstructed by using skin fibroblast cells from a Bactrian camel (Camelus bactrianus) as donor karyoplasts and dromedary camel (Camelus dromedarius) oocytes as recipient cytoplasts for investigating the developmental potential of the these embryos. Mature oocytes were collected from super-stimulated dromedary camels by ultrasound guided transvaginal ovum pick-up, 26 h after GnRH administration. Serum-starved adult Bactrian camel skin fibroblast cells were injected in to the perivitalline space of enucleated dromedary oocytes. The fibroblast cells and recipient cytoplasm were fused by two DC pulses of 100 V/cm for 15 μs each using an Eppendorf electroporator at room temperature. Reconstructs were activated 1 h postfusion with 5μM ionomycine followed by exposure to 6-dimethylaminopurine for 4 h. The activated oocytes were then transferred to 500 μL of embryo culture medium I (modified potassium simplex optimization medium with essential and non-essential amino acids [KSOMaa] supplemented with 1% BSA) and cultured at 38.5°C in an atmosphere of 5% CO2, 5% O2, and 90% N2 in air. On Day 3 (Day 0 = day of activation) the cleaved embryos were transferred into 500μL of embryo culture medium II (modified KSOMaa supplemented with 10% FCS) and cultured under the same conditions until Day 7. The proportion of oocytes that cleaved was recorded on Day 3, and those that reached morula and blastocyst stages were recorded on Day 7 of culture. The embryos reconstructed from dromedary camel (Camelus dromedarius) fibroblasts and oocytes were treated in similar manner and worked as control. Out of 58 reconstructed embryos, in 3 replicates, 77.4 ± 2.1 couplets fused successfully and were cultured after activation. The embryos that cleaved (59.1 ± 5.7) and those developed to the blastocyst stage (34.4 ± 3.9) were not different from the control group. This study demonstrated, for the first time, that somatic cells from Bactrian camel can be reprogrammed in the dromedary camel ooplasm and such interspecies nuclear transfer embryos can develop to the blastocyst stage. Further studies are needed to see the feasibility of transferring these embryos into dromedary camel recipients and the possibility of producing Bactrian camel calves from dromedary recipient camels. (platform)