Ca2+ Gradients, cGMP and the Cytoskeleton in Symmetry Breaking in Pelvetia Zygotes

IBN 9600568 肯尼思河私家侦探罗宾逊 发育生物学的一个中心问题是，模式是如何从相对无模式的卵中出现的。褐藻的卵对于解决这个问题特别有用，因为它们在受精时完全没有图案。这些细胞通过形成它们的初级发育轴和远离光源发芽来对单侧蓝光做出反应。我们的研究旨在了解细胞将光信号转化为局部生长反应的机制。初步结果表明，一个小的，可溶性分子，环GMP，是响应于光产生，并以某种方式指导后来的事件。我们将进行实验来验证这一假设，并将使用抗体来绘制暴露于光下的细胞中环GMP的分布。值得注意的是，这些低等植物似乎使用的感觉机制与脊椎动物用于检测光的眼睛密切相关。下一步将是了解环GMP的变化是如何耦合到后来的事件。有证据表明钙离子参与其中，因此我们将尝试绘制钙在响应细胞中的分布。最后，我们将探索钙的可能下游靶点。一种叫做钙调素的钙结合蛋白似乎与此有关，我们将测试这一想法。此外，植物形式的肌肉蛋白，肌动蛋白，已被证明是必要的发芽，所以我们将研究该蛋白质的调节钙。

IBN 9600568 Kenneth R. Robinson, P.I. A central problem of developmental biology is how pattern emerges from the relatively unpatterned state of the egg. The eggs of the brown algae are especially useful for the approaching this problem because they are completely unpatterned at the time of fertilization. These cells respond to unilateral blue light by forming their primary developmental axis and germinating away from the light source. Our research aims to understand the mechanisms whereby the cells convert the light signal to a localized growth response. Preliminary results indicate that a small, soluble molecule, cyclic GMP, is produced in response to light and somehow directs the later events. We will carry out experiments to test this hypothesis and will use antibodies to map the distribution of cyclic GMP in cells that have been exposed to light. It is remarkable that these lower plants seem to use a sensory mechanism that is closely related to that used by the vertebrate eye for detecting light. The next step will be to understand how the cyclic GMP changes are coupled to the later events. There is evidence that calcium ions are involved, so we will attempt to map the distribution of calcium in responding cells. Finally, we will explore the possible downstream targets of calcium. A calcium-binding protein called calmodulin appears to be involved and we will test this idea. Also, the plant version of the muscle protein, actin, has been shown to necessary for germination, so we will study the regulation of that protein by calcium.