Satoh Hiroyuki, Shinagawa Atsunori
Department of Biology, Faculty of Science, Yamagata University, Yamagata 990, Japan.
Dev Growth Differ. 1990 Dec;32(6):609-617. doi: 10.1111/j.1440-169X.1990.00609.x.
The rotation of subcortical cytoplasm relative to egg surface ("subcortical rotation", 28) is known to specify the dorso-ventral axis of fertilized Xenopus eggs. However, except for brief descriptions (14, 15), no information has been provided on the process of the dorso-ventral axis specification in nuclear transplanted Xenopus eggs. This study shows that (i), among the events that occur in association with dorso-ventral axis specification in fertilized Xenopus eggs, only the subcortical rotation occurs in a normal manner in both nuclear transplanted and non-nuclear transplanted (enucleated) Xenopus eggs, (ii), in these eggs, there is no factor that appears to affect the direction of subcortical rotation as the sperm entry point does in fertilized eggs: neither the site of pricking for activation nor that of injection for nuclear transplantation affects the direction of the subcortical rotation in those eggs and (iii) the subcortical rotation in nuclear transplanted eggs predicts very precisely the direction of their dorso-ventral axis as it does in fertilized eggs. These results suggest that matured Xenopus oocytes have a cytoplasmic potential to induce subcortical rotation along a particular meridian in the absence of a sperm aster and that the subcortical rotation induced by this cytoplasmic potential specifies the dorso-ventral axis in nuclear transplanted Xenopus eggs as in fertilized eggs.
已知爪蟾受精卵的皮层下细胞质相对于卵表面的旋转（“皮层下旋转”，参考文献28）决定了其背腹轴。然而，除了简短的描述（参考文献14、15）外，关于核移植爪蟾卵中背腹轴决定过程的信息尚未有报道。本研究表明：（i）在爪蟾受精卵背腹轴决定过程中发生的一系列事件中，只有皮层下旋转在核移植和未核移植（去核）的爪蟾卵中均正常发生；（ii）在这些卵中，不存在像精子进入点那样影响皮层下旋转方向的因素：无论是激活时的针刺位点还是核移植时的注射位点，均不影响这些卵中皮层下旋转的方向；（iii）核移植卵中的皮层下旋转与受精卵一样，能非常精确地预测其背腹轴的方向。这些结果表明，成熟的爪蟾卵母细胞具有在没有精子星体的情况下沿特定子午线诱导皮层下旋转的细胞质潜能，并且这种细胞质潜能诱导的皮层下旋转如同在受精卵中一样，决定了核移植爪蟾卵的背腹轴。
