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

点击翻译按钮获取中文摘要

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.