Barnes F L, Robl J M, First N L
Biol Reprod. 1987 Jun;36(5):1267-74. doi: 10.1095/biolreprod36.5.1267.
Enucleated mouse zygotes receiving eight-cell nuclei rarely develop beyond the two-cell stage, whereas enucleated two-cell embryos with eight-cell nuclei develop to blastocysts, and a few develop to midgestation. In this study the function of eight-cell nuclei in either the zygote or two-cell recipient was assessed by monitoring several nuclear-dependent events. These included methionine uptake, qualitative changes in protein synthesis, the time of blastocoele formation, and changes in nuclear volume. Although enucleated zygotes with nuclei from eight-cell embryos did not develop past the two-cell stage and had abnormally low levels of methionine uptake, they did show a normal zygote-to-two-cell transition in the types of polypeptides synthesized. Enucleated two-cell embryos with eight-cell nuclei formed blastocysts on schedule with the recipient cell stage and reached levels of methionine uptake equivalent to control embryos. The types of proteins synthesized by two-cell embryos with eight-cell nuclei indicated that the nucleus was developing partly in accord with its own developmental program. Transplanted nuclei did not enlarge to acquire the volume of the recipient cell's nucleus in either the zygote or the two-cell recipient. These results indicate that the difference in development between zygotes and two-cell embryos (each with eight-cell nuclei) may be the result of a greater overlap of function between the two-cell and eight-cell stages, rather than the extent of nuclear reprogramming. Nuclear function was not completely normal in either type of embryo, which may explain their failure to develop to term.
接受八细胞期细胞核的去核小鼠受精卵很少能发育到二细胞期之后，而带有八细胞期细胞核的去核二细胞胚胎则能发育到囊胚期，少数还能发育到妊娠中期。在本研究中，通过监测几个依赖于细胞核的事件来评估八细胞期细胞核在受精卵或二细胞期受体中的功能。这些事件包括蛋氨酸摄取、蛋白质合成的定性变化、囊胚腔形成的时间以及核体积的变化。虽然来自八细胞胚胎的细胞核的去核受精卵没有发育超过二细胞期，且蛋氨酸摄取水平异常低，但它们在合成的多肽类型上确实显示出从受精卵到二细胞期的正常转变。带有八细胞期细胞核的去核二细胞胚胎按照受体细胞阶段的时间形成了囊胚，并且蛋氨酸摄取水平达到了与对照胚胎相当的程度。带有八细胞期细胞核的二细胞胚胎合成的蛋白质类型表明，细胞核部分地按照其自身的发育程序进行发育。在受精卵或二细胞期受体中，移植的细胞核都没有增大到受体细胞核的体积。这些结果表明，受精卵和二细胞胚胎（均带有八细胞期细胞核）在发育上的差异可能是由于二细胞期和八细胞期之间功能重叠更大，而不是核重编程的程度。在这两种类型的胚胎中，核功能都不完全正常，这可能解释了它们无法发育到足月的原因。
