GENETIC CONTROL OF MEMBRANE CURRENTS

本项目的长期目标是确定 基因组决定可兴奋细胞的膜电流。 所有 研究是电生理学的，采用吸引电极电压钳 技术（通常被称为“膜片钳”技术， 电极开口小于2 μ m），可进行高度详细的分析 膜的电特性。 三种方法将是 跟踪了 第一种方法是寻找控制机制。 灵敏度 蜗牛（蜗牛）神经元膜电流的细胞内信使 将在隔离的膜片中进行分析。 尤其是 将检查细胞内Ca ~（2+）和H ~（++）的明显作用 阻断Ca电流并激活K和非特异性电流。 的作用 细胞内磷酸化在控制钙和钾电流中的作用， 追究 单通道质子流的大小将是 测定 第二种方法侧重于基因组控制的动态方面。 的 在培养的成年蜗牛中发生的膜兴奋性变化 （Helisoma）神经元和发育中的胚胎果蝇神经和肌肉 细胞将被研究。 这些研究将确定 分离后分化的膜，时间过程， 未分化的膜获得其兴奋性， 与神经突生长相关的电流。 第三种方法将剖析膜的遗传控制的要素 兴奋性通过表征膜电流的变化， 从突变。 膜片钳研究将在果蝇神经上进行， 从突变果蝇的卵中培养出的胚胎中的肌肉细胞。 行为突变体，有相当多的证据表明， 首先检查缺陷，例如振动筛和Nap。 由于细胞内Ca ~（2+）在控制递质中的重要性， 释放、肌肉收缩和其他细胞功能，主要 将注意到钙电流和重叠的钾电流， 确定Ca 2+流入细胞。 发现的机制或 该项目将大大有助于 了解涉及改变状态的神经和肌肉疾病 膜兴奋性或突触功效的影响。

The long-term goal of this project is to determine the mechanisms by which the genome determines the membranc currents of excitable cells. All studies are electrophysiological, employing suction-electrode voltage-clamp techniques (often referred to as "patch clamp" techniques when the electrode opening is less than 2Mum) that allow a higly detailed analysis of the electrical properties of the membrane. Three approaches will be followed. The first approach is a search for mechanisms of control. The sensitivity of snail (Lymnaea) neuron membrane currents to intracellular messengers will be analyzed in isolated patches of membrane. In particular, an examination will be made of the apparent roles of intracellular Ca2+ and H+ to block Ca current and to activate K and non-specific currents. The role of intracellular phosphorylation in controlling both Ca and K currents will be investigated. The size of single-channel proton currents will be determined. The second approach focuses on the dynamic aspect of genome control. The changes in membrane excitability that occur in cultured adult snail (Helisoma) neurons and developing embryonic Drosophila nerve and muscle cells will be studied. These studies will determine the stability of differentiated membranes after isolation, the time course with which the undifferentiated membrane gains its excitability, and the somal membrane currents associated with neurite growth. The third approach will dissect the elements of genetic control of membrane excitability by characterizing the changes in membrane currents that result from mutations. Patch clamp studies will be made on Drosophila nerve and muscle cells in embryo cultures made from the eggs of mutant flies. Behavioral mutants for which there is considerable evidence of a membrane defect, e.g. Shaker and Nap, will be examined first. Due to the importance of intracellular Ca2+ in controlling transmitter release, muscle contraction, and other cellular functions, primary attention will be given to the Ca current and overlapping K currents, which determine the influx of Ca2+ into the cell. Mechanisms discovered or elucidated by this project will contribute significantly to the understanding of neural and muscular diseases that involve altered states of membrane excitability or synaptic efficacy.