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。果蝇是研究发育过程中铅暴露影响的一个有前途的模式生物，因为（1）对其遗传学的复杂理解，以及操纵其基因组的容易性;（2）行为和形态学分析对极低剂量铅的微小影响敏感。人们认为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。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。为了验证这一假设，目的1是地图铅敏感的QTL暴露幼虫的90重组近交果蝇品系环境相关剂量的铅，并测定几个行为和突触连接方面的影响铅-如幼虫运动，成人学习，成人运动，成人运动结合乙醇蒸汽暴露，和幼虫神经肌肉接头的结构。目的2是进行DNA微阵列分析与标记的mRNA从整个幼虫和成人头部的重组近交系，表现出最大的差异，铅诱导的行为改变，确定在目的1。目的3是通过条件性过表达上调或通过使用现有突变和RNA干扰技术下调在目的1和2中进行的测定中重叠的基因，并确定铅对这些遗传改变的果蝇的认知、运动和突触功能的影响。这些研究的结果将确定在人类铅暴露过程中发生改变的最重要基因的候选基因，并可能导致对处于或低于NOAEL和LOAEL值的重金属暴露进行生物测定或治疗。

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"). Drosophila is a promising model organism to study the effects of lead exposure during development because of (1) the sophisticated understanding 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 thought to be 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. 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, Aim 1 is to map lead sensitive QTL by exposing larvae of 90 recombinant inbred Drosophila strains to environmentally relevant doses of lead, and assaying several behavioral and synaptic connection aspects that are affected by lead - such as larval locomotion, adult learning, adult locomotion, adult locomotion combined with ethanol vapor exposure, and the structure of the larval neuromuscular junction. Aim 2 is to perform DNA microarray analyses with labeled mRNA from whole larvae and adult heads from the recombinant inbred lines that show the greatest differences in lead-induced behavioral alterations, as determined in Aim 1. Aim 3 is to up-regulate, by conditional over-expression, or down-regulate, by using existing mutations and RNA interference techniques, the genes that overlap in the assays performed in Aims 1 and 2, and to determine the effects of lead on cognition, locomotion and synaptic function of these genetically altered flies. 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 at or below NOAEL and LOAEL values.