QTL and Microarray Mapping Lead Sensitivity Genes

描述(申请人提供)：人类活动导致了许多有毒物质在环境中的分布，其中包括遍布我们生物圈的重金属。除了铅对人类的急性毒性影响外(即在含铅涂料或受污染的饮用水中)，长期接触对所有生物体的发育也有更多的潜在影响。暴露在低水平铅中的儿童会改变发育过程，这些儿童会出现多动、感觉功能改变和认知能力(智商)改变等症状。在这个项目的头5年里，我们在使用果蝇作为模式生物来研究发育过程中铅暴露的影响方面取得了相当大的进展，使用：(1)对其遗传学的复杂理解，以及对其基因组操作的简便性；(2)对极低剂量铅的小影响敏感的行为和形态分析的可用性。铅暴露的敏感性有很大的变异性，人类和果蝇细胞都被认为在暴露于铅时诱导“保护性基因”的表达。行为是铅致神经毒性的一个特别敏感的终点，因为它是神经系统感觉、运动和认知功能的净结果。这一提议的假设是，人们可以利用数量性状基因座(QTL)定位技术，结合微阵列和复杂的遗传分析，识别使有机体对铅毒性的行为和发育影响产生抵抗力的一些“保护基因”。为了验证这一假设，我们提出了三个目标。目的1在标记基因30AB和50DF上找出影响运动功能的基因和基因表达。目的2是寻找与幼虫突触钙离子传导有关的新的QTL。目标3是将我们的发现从苍蝇转移到暴露在环境中铅的人类身上。在这个目标中，我们将确定特定的CpG位点DNA甲基化水平是否与底特律大都市地区儿童采集的血液中的铅水平相关。这些研究的结果将确定在人类接触铅期间发生变化的最重要基因的候选基因，并很可能导致对人类重金属暴露的生物检测或治疗。 与公共健康相关：世界上超过1.2亿人的血铅水平超过每分升10微克，这是美国疾病控制中心认为的“安全水平”。我们正在继续一个项目，利用复杂的遗传学和基因组学技术来了解为什么一些品系的果蝇对铅的神经毒理效应更敏感。在接下来的5年里，我们将开始研究铅如何影响血液水平较高的儿童的DNA甲基化，并确定果蝇和人类之间的共同调控机制。

DESCRIPTION (provided by applicant): Human activity has resulted in the environmental distribution of many toxic substances, among them the heavy metals that are spread throughout our biosphere. In addition to the acute toxic effects to humans exposed to lead (i.e. in lead paint or in contaminated drinking water) there are more insidious effects of chronic exposure on the development of all organisms. Children exposed to low levels of lead have altered developmental processes, and these children develop symptoms such as hyperactivity, changes in sensory function, and changes in cognitive abilities ("IQ"). We have made considerable progress during the first 5 years of this project in using Drosophila as a model organism to study the effects of lead exposure during development by using: (1) the sophisticated under-standing of its genetics, and the ease of manipulating its genome; (2) the availability of behavioral and morphological assays sensitive to small effects of very low doses of lead. There is a great deal of variability in the sensitivity of lead exposure, and both human and Drosophila cells are thought to induce expression of "protective genes" upon exposure to lead. Behavior is an especially sensitive end point of lead-induced neurotoxicity because it is a net result of sensory, motor, and cognitive functions in the nervous system. The hypothesis for this proposal is that one can identify some of the "protective genes" that make an organism resistant to the behavioral and developmental effects of lead toxicity using quantitative trait loci (QTL) mapping techniques combined with microarray and sophisticated genetic analyses. To test this hypothesis, we propose 3 Aims. Aim 1 Identify the genes that affect locomotor activity and gene expression at marker loci 30AB and 50DF. Aim 2 is to identify new QTLs that are involved in calcium conduction at the larval synapse. Aim 3 is to translate our findings from flies to humans exposed to lead from the environment. In this aim, we will determine whether specific CpG site DNA methylation levels correlate with lead levels in blood collected from children in the Detroit metropolitan area. Results of these studies will identify candidates for the most important genes that are altered during lead exposure in humans, and could well lead to bioassays or treatments for heavy metal exposure in humans. PUBLIC HEALTH RELEVANCE: Over 120 million people in the world have blood lead levels of greater than 10 micrograms per deciliter, which is considered the 'safe level' by the Centers for Disease Control. We are continuing a project that uses sophisticated genetics and genomics techniques to understand why some strains of Drosophila are more sensitive to the neurotoxicological effects of lead. In the next 5 year period, we will begin studies to see how lead affects DNA methylation in children with high blood levels and determine the common regulatory mechanisms between Drosophila and humans.