Ionic Mechanisms in the Initiation of Development

这项研究的最终目的是深入了解受精过程中卵子激活的机制。重点将研究如何膜电位变化作为信号转导到细胞内过程后精子附着。电压固定卵的电生理测量将与视频数字图像处理相结合，以将电事件与(a)难以分辨的活细胞形态学变化相关联，(b)使用荧光标记的肌动蛋白或phallicidin进行皮质肌动蛋白丝聚集的发生，以及(c)细胞内ıCa2+！和pH，并利用荧光指示剂和图像分级方法定位这些变化。静息（-70mV）附近的膜电位抑制精子进入（尽管激活仍在进行）的机制研究将继续进行。精子进入的抑制可能是负膜电位对肌动蛋白丝组装的影响的结果。钱伯斯博士的实验室多年来一直致力于研究海胆卵在受精时激活的生理学。之所以在这些研究中选择海胆蛋，是因为这种蛋（其大小和蛋黄含量与人类鸡蛋大致相同）透明、大、容易大量获得，而且经得起实验室操作。在更广泛的背景下，该研究旨在了解静止细胞被激活进行有丝分裂、细胞分裂和生长的机制。

The ultimate objective of this research is to obtain insight into the mechanisms concerned in the activation of the egg during fertilization. Emphasis will be on investigating how membrane potential changes as signals are transduced into intracellular processes following sperm attachment. Electrophysiological measurements on voltage clamped eggs will be combined with video digital image processing to correlate electrical events with (a) morphological changes in the living cell difficult otherwise to resolve, (b) the occurrence of cortical actin filament assembly using fluorescently labeled actin or phallicidin, and (c) changes in intracellular ıCa2+! and pH and the localization of these changes using fluorescent indicators and image ratioing methods. Investigation of the mechanism whereby membrane potentials in the neighborhood of resting (-70mV) suppress sperm entry (although activation proceeds) will be pursued. The possibility that the suppression of sperm entry is the consequence of an effect of negative membrane potential on assembly of actin filaments will be investigated. Dr. Chambers's laboratory has been active for many years in the study of the physiology of sea urchin egg activation at fertilization. The sea urchin egg is chosen in these studies because this egg (which has about the same size and yolk content as the human egg) is transparent, large, readily available in large numbers and withstands laboratory manipulations. In a more general context, the research is directed toward understanding the mechanisms whereby a quiescent cell, at rest, is activated to undergo mitosis, cell division and growth.