| The successes of somatic clone in many domestic and experimental animals have shown the differential cells have the whole genetic information which direct embryo completes its development. The somatic clone not only have important value on Development Biology, gene regulation and nucleo-cytoplasm corresponding, but also have application and economic prospect in biological medicine and livestock breeding. However, the success rate is very low and the defection and abnormality rate of clone offspring is very high. It is presumed that the reasons of low pregnant and high birth rate were the donor cells are not be reprogrammed besides the nuclear transfer procedure and embryo cultural system in vitro. It is known very little on the genome reprogramming and ultrastructure of nucleo-transferred embryo. This experiment detected the telomerase activity of Boer goat embryo during pre-implantation. It will be useful for goat nuclear transfer studies. The Boer goat ear skin fibroblast nucleo-transferred embryos and bovine-goat(Boer) interspecies clone embryos have been evaluated by studying the ultrastructure of Boer goat embryos in vivo. The experiment detected the telomerase activity of oocytes, 4-cell, 8-cell, morula and blastocysts in Boer goat embryos by Telomere Repeat Amplication protocol(TRAP). The results show the Boer goat oocyte and pre-implantation embryo are telomerase positive. According to the densitometry of bands under the CCD imagine system, the total telomere repeats product generated (TPG) of oocytes, 4-cell, 8-cell, morulae and blastocyst are 25.348, 273.832, 56.117, 251.118, 519.46, respectively. The results show the lowest telomerase activity of Boer goat increase when fertilization, and then decrease to the 8-cell stage gradually. The telomerase activity rise up gradually when the activation of embryonic genome at 8-cell stage and to the highest level at blastocyst. The ultrastructure Boer goat embryo in vivo, goat intraspecies and bovine-goat interspecies cloned embryos are followed. The nucleolar has become reticulated at 4-cell stage in Boer goat ear skin fibroblast cloned embryos(gSCE). According to the nucleolar, the goat oocyte can remodel the same species somatic cell nuclear and support the somatic nuclear-transferred embryo development two cell circles at least. However, the dense-rounded nucleolar of bovine-goat interspecies cloned embryos(b-gSCM) at blastocyst stage shows that the bovine oocyte doesn't remodel the Boer goat ear fibroblast genome. The mitochondria in b-gSCM develop from immature mitochondria, having poorly developed, peripheral cristae or a hooded appearance to mature mitochondria, containing well-developed and evenly stacked cristae as the goat in vivo embryos., The quantitative analysis shows that mitochondria in nuclear-transferred embryo decrease compared to the goat in vivo embryo(gIVE) although normal mitochondrial shape(P<0.05). This indicates the nuclear genome and mitochondrial genome do not well corresponding each other. The mitochondria in (b-gSCM) also can become mature. However, a kind of abnormal mitochondria, that have multi-filiations, also are seen. The volume density of total mitochondria and mature mitochondria are lower than those in gIVE (P <0.05). The results implicate the goat nuclear genome can not direct the heterogeneous mitochondrial development completely. The volume density of lipid are greater in gSCE(P <0.05) and b-gSCM(P <0.05) compared to gIVE, but no difference between two kind cloned embryos. The volume density of vacuoles are greater in Boer goat somatic (P <0.05) and b-gSCM (P <0.05) compared to gIVE, but no difference between two kind cloned embryos. The results show the quality of goat cloned embryos is not good as those produced in vivo. |
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