以经过转染的乳腺上皮细胞生产克隆羊

Production of cloned goats by transfer of nuclei from transfected caprine mammary gland epithelial cells

为研究转基因乳腺上皮细胞发育的全能性,利用电转染方法将人乳铁蛋白(hLF)乳腺特异性表达载体电转染山羊乳腺上皮细胞,经G418和PCR筛选获得阳性克隆细胞株,经催乳素诱导的细胞株上清液用Western blotting方法检测hLF的表达。以转基因与上清液中表达hLF均为阳性的细胞为核供体细胞,进行山羊体细胞核移植。结果为:16株细胞表达重组hLF,分子质量为75 kD;将144枚重构胚移入16只同步发情的山羊输卵管中,在移植后的30 d、60 d和90 d的妊娠率分别为87.5%、81.3%和62.5%;最终3只受体妊娠足月,产下3只克隆羊,克隆效率为2.1%,PCR-RFLP分析表明克隆羊均来自供体羊细胞,但没有整合外源基因。结果表明,hLF转基因乳腺上皮细胞能分泌hLF;乳腺上皮细胞经转染、筛选和长期培养的条件下,能保持发育的全能性。

In this study, we evaluated the development potential of caprine mammary gland epithelial cells （CMGECs） after transfection and nuclear transfer into enucleated, ovulated oocytes. We first isolated CMGECs from udders of lactating goats which were transfected with expression plasmid for human lacterrin and selected by G418. Then we chose sixteen neomycin resistant lines and induced them with prolactin for the expression of human lactoferrin checked by Western blotting. The donor cells, expressing human lactoferrin of 75 kD, were fused and activated with enucleated ovulated oocytes. Pronuclear-stage reconstructed embryos were transferred into the oviducts of 16 recipient goats. There were fourteen （87.5%）, thirteen （81.3%）, and ten （62.5%） pregnancies confirmed pregnant by ultrasound on Day 30, 60, and 90, respectively. Three recipients carried the pregnancies to term and delivered one goat each. Nested PCR-RFLP analysis confirmed that all of the kids were clones of the donor cells. These results demonstrated that CMGECs after transfection remain totipotent for nuclear transfer.