Kao K R, Masui Y, Elinson R P
Nature. 1986;322(6077):371-3. doi: 10.1038/322371a0.
Much interest in vertebrate embryology is now focused on early pattern formation in the frog, Xenopus laevis. In this species, the body plan is specified by a stable positional system set up by a cytoplasmic rotation in the zygote that occurs before first cleavage. Perturbation of this initial cellular event by a variety of means causes permanent distortions of the positional system. Until now it has not been possible to alter the positional system after it has been specified. However, we report here that lithium, when applied after specification of the body plan, can respecify the positional system of the Xenopus embryo such that dorsal, axial structures develop from cells that otherwise contribute to ventral structures. Lithium is usually considered to have negative effects on early embryo development, but our results show that lithium can act in a positive manner to produce structures which represent the uppermost values of the positional system. This discovery introduces a convenient means to study cellular and molecular mechanisms of early vertebrate pattern expression.
目前，脊椎动物胚胎学的许多研究兴趣都集中在非洲爪蟾（Xenopus laevis）的早期模式形成上。在这个物种中，身体模式是由合子中的细胞质旋转建立的稳定位置系统所确定的，这种旋转发生在第一次卵裂之前。通过各种方式干扰这一初始细胞事件会导致位置系统的永久性扭曲。到目前为止，在位置系统已经确定之后，还无法对其进行改变。然而，我们在此报告，锂在身体模式确定后施加时，可以重新确定非洲爪蟾胚胎的位置系统，使得背侧、轴向结构从原本会形成腹侧结构的细胞发育而来。锂通常被认为对早期胚胎发育有负面影响，但我们的结果表明，锂可以以积极的方式起作用，产生代表位置系统最高值的结构。这一发现引入了一种便捷的方法来研究早期脊椎动物模式表达的细胞和分子机制。
