Sequence differences are considered to be the basic cause of developmental failure in interspecies embryos when more distant species are combined. However, other phenomena, such as insufficient or excessive quantity of specific cellular factors, might also influence the outcome. These effects are usually not considered. One of the organelles shown to contain different amount of proteins is the oocyte nucleolus-like body. Here we show that upon interspecies transfer, a single porcine nucleolus-like body is unable to support the development of a mouse parthenogenetic embryo derived from an enucleolated oocyte. However, when the amount of the porcine nucleolar material is increased to equalize the amount of mouse nucleolar material by transferring two nucleolus-like bodies, mouse embryos are able to pass the developmental block elicited by enucleolation. These embryos progress to the blastocyst stage at rates comparable to controls. Thus, using the model of an interspecies nucleolus-like body transplantation between mouse and pig oocytes, we show that an inadequate amount of nucleolar factors, rather than the species origin, affects the development. In a wider context of interspecies nuclear transfer schemes, the observed incompatibility between more distant species might not stem simply from sequence differences but also from improper dosage of key cellular factors.

中文翻译：

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评估种间卵母细胞核仁材料剂量对胚胎发育的影响

当更远的物种组合时，序列差异被认为是种间胚胎发育失败的基本原因。然而，其他现象，例如特定细胞因子的数量不足或过多，也可能影响结果。通常不考虑这些影响。显示含有不同数量蛋白质的细胞器之一是卵母细胞核仁样体。在这里我们表明，在种间转移时，单个猪核仁样体无法支持来自去核卵母细胞的小鼠孤雌生殖胚胎的发育。然而，当通过转移两个核仁样小体来增加猪核仁材料的量以平衡小鼠核仁材料的量时，小鼠胚胎能够通过去核引起的发育阻滞。这些胚胎以与对照相当的速度进入囊胚阶段。因此，使用小鼠和猪卵母细胞之间的种间核仁样体移植模型，我们表明，核仁因子的数量不足，而不是物种起源，会影响发育。在更广泛的种间核转移方案的背景下，观察到的更远距离物种之间的不相容性可能不仅源于序列差异，还源于关键细胞因子的不当剂量。而不是物种起源，影响发育。在更广泛的种间核转移方案的背景下，观察到的更远距离物种之间的不相容性可能不仅源于序列差异，还源于关键细胞因子的不当剂量。而不是物种起源，影响发育。在更广泛的种间核转移方案的背景下，观察到的更远距离物种之间的不相容性可能不仅源于序列差异，还源于关键细胞因子的不当剂量。