Valles James M, Wasserman Sarah R R M, Schweidenback Caterina, Edwardson Jill, Denegre James M, Mowry Kimberly L
Department of Physics, Brown University, Providence, Rhode Island 02912, USA.
Exp Cell Res. 2002 Mar 10;274(1):112-8. doi: 10.1006/excr.2001.5456.
As in many organisms, the first three cleavage planes of Xenopus laevis eggs form in a well-described mutually orthogonal geometry. The factors dictating this simple pattern have not been unambiguously identified. Here, we describe experiments, using static magnetic fields as a novel approach to perturb normal cleavage geometry, that provide new insight into these factors. We show that a magnetic field applied during either or both of the first two cell cycles can induce the third cell cycle mitotic apparatus (MA) at metaphase and the third cleavage plane to align nearly perpendicular to their nominal orientations without changing cell shape. These results indicate that processes occurring during the first two cell cycles primarily dictate the third cleavage plane and mitotic apparatus orientation. We discuss how mechanisms that can align the MA after it has formed are likely to be of secondary importance in determining cleavage geometry in this system.
与许多生物体一样，非洲爪蟾卵的前三个分裂平面以一种描述详尽的相互正交的几何形态形成。决定这种简单模式的因素尚未得到明确鉴定。在此，我们描述了一些实验，利用静磁场作为一种干扰正常分裂几何形态的新方法，这些实验为这些因素提供了新的见解。我们表明，在前两个细胞周期的任何一个周期或两个周期中施加磁场，都可以诱导处于中期的第三个细胞周期有丝分裂器（MA）以及第三个分裂平面几乎垂直于其标称方向排列，而不改变细胞形状。这些结果表明，在前两个细胞周期中发生的过程主要决定了第三个分裂平面和有丝分裂器的方向。我们讨论了在该系统中，有丝分裂器形成后能够使其排列的机制在确定分裂几何形态方面可能是次要的。
