Studies on biotechnology in experimental and domestic animals : cloning and nuclear transfer

本研究旨在建立动物遗传改良和繁殖的克隆技术。结果表明：1.移植后的小鼠胚胎发生了胚胎丢失、发育迟缓、体积缩小以及随后的发育调节。桑椹胚期胚胎细胞数量的减少会影响滋养层细胞的外向生长、内胚层的形成和体外发育到卵圆柱期。2.小鼠2、4、8细胞期孤雌胚胎和4细胞期卵裂球的聚合胚胎移植后，获得了具有毛色嵌合体的后代。3.未受精的成熟卵母细胞的细胞质具有对小鼠2~8细胞胚胎的细胞核进行重编程的能力。在核移植胚胎中，细胞核和细胞质之间的相互作用是重编程所必需的。细胞周期早期胚胎的核应移植到去核未受精的成熟卵母细胞的细胞质中。4.体外受精的牛卵母细胞在化学定义的培养液中成功地培养到囊胚期。用诺康唑处理核供体胚胎，用乙醇和放线菌酮处理受体卵母细胞，可提高核移植胚胎的囊胚期发育率。牛核移植胚胎移植后获得后代。

The present study was conducted to establish cloning techniques for genetic improvement and multiplication of animals. The following results were obtained : 1.Embryonic loss, retardation of development, decrease in size and subsequent regulation of development were demonstrated after transfer of mouse bisected embryos. A decrease in the number of embryonic cells at the morula stage affects trophoblast outgrowth, endoderm formation and development to the egg cylinder stage in vitro, 2.Offspring with coat color chimera were obtained after transfer of mouse aggregated embryos from 2-, 4- and 8-cell stage parthenogenetic embryos and 4-cell stage blastomeres, 3.Cytoplasm of unfertilized mature oocytes was demonstrated to have the ability of reprogramming the nuclei of mouse 2-to 8-cell embryos. Interaction between the nucleus and cytoplasm is required for reprogramming in the nuclear transferred embryos. The nucleus of the embryo at the early cell-cycle-stage should be transferred to cytoplasm of enucleated unfertilized mature oocyte, 4.Bovine oocytes derived from in vitro fertilization were successfully cultured to the blastocyst stage in chemically defined medium. Developmental rate of the nuclear transferred embryos to the blastocyst stage was improved when nuclear donor embryos were treated with nocodazole and recipient oocytes were treated with ethanol and cycloheximide. Offspring was obtained after transfer of bovine nuclear transferred embryos.