Xenopus Oocyte Polarity and Meiotic Maturation

非洲爪蟾卵母细胞经过长时间的生长后，在卵巢中处于发育停滞状态。在黄体酮的作用下，卵母细胞恢复减数分裂，从周围的卵泡细胞中释放出来，成为一个受精卵。罗宾逊博士已经证明，这一过程不涉及钙的增加，至少在钙微电极或钙蛋白可以检测到的范围内。利用他改良的荧光显微镜和钙指示剂fura 2，他提议探测皮层区域约10微米的深度。在质膜下，确定在成熟过程中钙是否增加或减少。罗宾逊博士还将寻找与卵母细胞的动物-植物轴相关的钙梯度。这些测量将扩展到正在发育和表达初级极性轴的较小卵母细胞。使用荧光偏振的方法，罗宾逊博士将测量由类固醇和非类固醇激动剂诱导的成熟过程中的膜流动性，目的是确定共同的作用机制。罗宾逊博士将与苏珊·斯特罗姆博士合作，将钙和振动探针的测量扩展到秀丽隐杆线虫卵母细胞和受精卵的早期发育。本研究的意义在于两个方面。首先是类固醇激素与细胞相互作用的机制。长期以来，人们一直认为类固醇激素直接作用于遗传机制。另一方面，在两栖动物卵母细胞中，虽然表面激素相互作用的性质尚不清楚，但已知黄体酮在细胞表面起作用。最近，表面效应是类固醇激素作用的一个普遍特征。这项工作的第二个方面解决了模式形成的重要问题。

The Xenopus oocyte, after undergoing a prolonged period of growth, remains in a state of developmental arrest in the ovary. In response to progesterone, the oocyte resumes meiosis, is released from the surrounding follicle cells, and becomes a fertilizable egg. This process has been shown by Dr. Robinson not to invlove an increase in calcium, at least insofar as can be detected by calcium microelectrodes or aequorin. Using his modified fluorescence microscope and the calcium indicator fura 2, he propose to probe the cortical region to a depth of about 10microm. underneath the plasma membrane and determine if there are increases or decreases in calcium during the maturation process. Dr. Robinson will also look for gradients of calcium associated with the animal-vegetal axis of the oocytes. These measurements will be extended to the smaller oocytes that are in the process of developing and expressing the primary polarity axis. Using the method of fluorescence polarization, Dr. Robinson will measure membrane fluidity during maturation induced by steroid and non-steroid agonists, with the aim of identifying a common mechanism of action. In collaboration with Dr. Susan Strome, Dr. Robinson will extend the calcium and vibrating probe measurements to the early development of Caenorhabditis elegans oocytes and zygotes. The significance of this research lies to two areas. The first is that of the mechanism of steroid hormone interaction with cells. It has long been thought that steroid hormones exert their effects directly on the genetic machinery. In the amphibian oocyte on the other hand, progesterone is known to have its effect at the surface of the cell, although the nature of the surface-hormone interaction is unknown. Recently, it has become apparent that a surface effect is a general feature of steroid hormone action. The second aspect of this work addresses the important problem of pattern formation.