Goda Makoto, Inoué Shinya, Mabuchi Issei
Structural Physiology Research Group, RIKEN Spring8 Center, Harima Institute, 1-1-1 Kouto, Sayo, Hyogo 679-5148, Japan.
Biol Bull. 2009 Feb;216(1):40-4. doi: 10.1086/BBLv216n1p40.
Calyculin-A (CLA), a protein phosphatase inhibitor, has been known to induce cleavage resembling normal furrowing in unfertilized sea urchin eggs. In CLA-treated eggs, actin filaments and myosin assemble to form a contractile ring-like structure in the egg cortex; however, this occurs in the absence of a mitotic spindle or asters. Here, we investigated the relationship between the plane of CLA-induced cleavage and the intrinsic animal-vegetal polar axis in sea urchin eggs. The animal-vegetal axis was established using black ink to visualize the jelly canal located at the animal pole in the jelly coat surrounding the egg. We measured the acute angle between the jelly canal axis and the cleavage plane for both fertilized eggs and CLA-treated unfertilized eggs. Although the acute angle lay within 10 degrees for most of the fertilized eggs, it varied widely for CLA-treated unfertilized eggs. Measurements of the diameter of blastomeres revealed that cleavage of fertilized eggs took place in the mid-plane of the egg, but that CLA-induced divisions were unequal. These results suggest that neither the orientation nor the location of the CLA-induced cleavage furrow is related to the animal-vegetal polar axis of the egg, even though the furrowing mechanism itself is not dissimilar to that in fertilized eggs.
抑癌蛋白磷酸酶抑制剂花萼海绵诱癌素A（CLA），已知可诱导未受精海胆卵发生类似正常卵裂沟的卵裂。在经CLA处理的卵中，肌动蛋白丝和肌球蛋白组装形成位于卵皮质的收缩环样结构；然而，这一过程是在没有有丝分裂纺锤体或星体的情况下发生的。在此，我们研究了CLA诱导的卵裂平面与海胆卵固有的动物-植物极轴之间的关系。通过使用黑色墨水来可视化位于卵周围卵胶膜动物极的卵胶管，从而确定动物-植物轴。我们测量了受精卵和经CLA处理的未受精卵的卵胶管轴与卵裂平面之间的锐角。虽然大多数受精卵的锐角在10度以内，但经CLA处理的未受精卵的锐角变化很大。对卵裂球直径的测量表明，受精卵的卵裂发生在卵的中平面，但CLA诱导的分裂是不等的。这些结果表明，尽管CLA诱导的卵裂沟的形成机制与受精卵的并非不同，但CLA诱导的卵裂沟的方向和位置均与卵的动物-植物极轴无关。
