Cleavage in Xenopus Development

Danilchik新生物体生命中最关键的阶段之一是卵裂，这是一系列快速、同步的细胞分裂，用合子核填充受精卵的体积，克隆分离其发育潜力，并将细胞体积减小到体细胞的体积。卵裂长期以来一直是研究动物细胞胞质分裂的最受欢迎的模型，因为卵子的大尺寸允许各种实验操作和观察较小细胞的机会。然而，已知裂解在几个基本方面与体细胞有丝分裂不同，特别是其同步性，快速性，缺乏转录活性，以及依赖于母体合成的成分。在两栖动物胚胎中，卵裂伴随着在每对新细胞之间插入一个新的质膜结构域。这种膜沉积在早期发育的事件中具有潜在的意义，例如身体计划的建立，因为所有受体介导的细胞-细胞相互作用都取决于细胞之间沉积的膜的组成。我们发现了一个独特的阵列的微管的基础上进行卵裂沟导致了一项调查的作用，微管在卵裂过程中。我们现在有证据表明，沟微管阵列可能参与递送囊泡到裂解沟底部的新膜扩张部位。此外，我们已经在扩展的裂解膜结构域的两侧检测到新的膜扩张活性，这可能是随着裂解进行将新细胞拉入紧密贴壁的关键。我们在这个项目中的目标是了解非洲爪蟾卵裂这些过程的功能和整合。具体来说，我们的目标是1）学习的作用，沟槽微管阵列在指导胞吐囊泡的增长分裂平面，2）分析活胚胎的沟槽中的细胞骨架组装，和3）研究沟槽和膜膨胀活动之间的关系沿着沟槽边缘。

0110985DanilchikOne of the most critical phases in the life of a new organism is cleavage, a series of rapid, synchronous cell divisions that populates the fertilized egg's volume with zygotic nuclei, clonally segregates its developmental potential, and reduces cell volume to that of somatic cells. Cleavage has long served as a favorite model for the study of animal-cell cytokinesis, since the egg's large size permits a variety of experimental manipulations and opportunities for observation unavailable in smaller cells. Nevertheless, cleavage is known to differ in several fundamental ways from somatic-cell mitosis, particularly by its synchrony, rapidity, lack of transcriptional activity, and reliance on maternally synthesized components. In amphibian embryos, cleavage is accompanied by the insertion of a new domain of plasma membrane between each new pair of cells. This membrane deposition has potential significance in events of early development, such as establishment of the body plan, since all receptor-mediated, cell-cell interactions depend on the composition of the membrane deposited between cells. Our discovery of a unique array of microtubules underlying the advancing cleavage furrow led to an investigation of the role of microtubules in the cleavage process. We now have evidence that the furrow microtubule array may be involved in delivery of vesicles to the site of new membrane expansion at the base of the cleavage furrow. Furthermore, we have detected novel membrane protrusive activity on either side of the expanding cleavage membrane domain that may be critical for pulling the new cells into close apposition as cleavage progresses. Our goal in this proposed project is to understand the function and integration of these processes in Xenopus cleavage. Specifically, our aims are to 1) learn the role of the furrow microtubule array in directing exocytotic vesicles to the growing cleavage plane, 2 ) analyze cytoskeletal assembly in furrows of living embryos, and 3) study the relationship between furrowing and membrane protrusive activity along the furrow margins.