QTL and Microarray Mapping Lead Sensitivity Genes

描述（由申请人提供）：人类活动导致了许多有毒物质的环境分布，其中包括遍布我们生物圈的重金属。除了对接触铅（即含铅涂料或受污染的饮用水）的人的急性毒性影响外，慢性接触对所有生物体的发育都有更为隐蔽的影响。接触低水平铅的儿童会改变发育过程，这些儿童会出现多动症、感觉功能改变和认知能力（"智商"）改变等症状。在本项目的前5年中，我们已经取得了相当大的进展，使用果蝇作为模式生物来研究发育过程中铅暴露的影响，通过使用：（1）对其遗传学的复杂理解，以及操纵其基因组的容易性;（2）对极低剂量铅的微小影响敏感的行为和形态学测定的可用性。铅暴露的敏感性有很大的差异，人类和果蝇细胞都被认为在暴露于铅时诱导“保护基因”的表达。行为是铅诱导神经毒性的一个特别敏感的终点，因为它是神经系统中感觉、运动和认知功能的净结果。这个建议的假设是，人们可以确定一些“保护基因”，使一个有机体的行为和发展的影响，铅毒性使用数量性状基因座（QTL）定位技术结合微阵列和复杂的遗传分析。为了验证这个假设，我们提出了三个目标。目的1在标记位点30AB和50DF上鉴定影响运动活动和基因表达的基因。目的二是鉴定新的参与幼虫突触钙离子传导的QTL。目标3是将我们的发现从苍蝇转化为暴露于环境中铅的人类。在这个目标中，我们将确定特定的CpG位点DNA甲基化水平是否与从底特律大都市区儿童血液中收集的铅水平相关。这些研究的结果将确定在人类铅暴露期间改变的最重要基因的候选者，并且很可能导致对人类重金属暴露的生物测定或治疗。 公共卫生相关性：世界上有超过1.2亿人的血铅水平超过每分升10微克，这被疾病控制中心认为是“安全水平”。我们正在继续一个项目，使用复杂的遗传学和基因组学技术，以了解为什么某些果蝇品系对铅的神经毒理学效应更敏感。在接下来的5年里，我们将开始研究铅如何影响高血铅水平儿童的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.