Neurogenetics of lead toxicity in Drosophila

描述(申请人提供)：重金属中毒是一个世界性的健康问题。由于低浓度铅对儿童认知发展的不利影响，铅暴露尤其令人担忧。虽然铅的神经毒性机制已经得到了很好的研究，但缺乏关于人类人群对铅暴露影响的遗传易感性的信息，以及旨在识别可能加剧或减轻暴露风险的等位基因的研究。这种信息很难获得，特别是在儿童中，因为很难量化暴露的开始、持续时间和程度，很难衡量铅暴露的不利影响，这些影响在发育的后期阶段变得明显，很难评估同时暴露于多种往往未知的环境毒素的影响，以及在考虑人口结构的同时获得足够的人口样本量。这些问题可以通过在模型系统中识别与人类同源的候选风险等位基因来规避，随后可以应用于对人类群体的翻译研究。黑腹果蝇提供了一个有利的模型，因为遗传背景和环境，包括铅的暴露，都可以被精确控制。此R21提案是一项探索性的可行性研究，旨在为后续的R01应用程序开发 果蝇遗传学的全部力量，以获得对铅暴露易感性的遗传基础的洞察。为了确定与铅暴露敏感性相关的等位基因，我们将利用来自具有完全测序的基因组的罗利种群(果蝇黑腹果蝇遗传参考小组，DGRP)的野生来源近交系群体，并利用DGRP小组内广泛的自然变异来进行全基因组关联研究(GWAS)。这项应用的具体目的是：(1)鉴定与铅暴露对发育时间、活力和运动活性的影响有关的常见DNA序列变异；(2)使用大规模平行批量DNA测序作为补充方法，识别与铅暴露影响相关的常见和稀有等位基因，这些等位基因分离于从极端敏感和抗性品系衍生的高级杂交群体中。我们将测量在有或没有醋酸铅暴露的情况下饲养的DGRP系的发育时间、活力和运动活性，并确定与铅敏感性变化相关的单核苷酸多态(SNPs)。随后的R01奖将侧重于对候选等位基因、它们之间的上位性相互作用以及决定对铅神经毒性敏感性的遗传网络和神经电路之间的联系进行更详细的验证和表征。这些实验的结果将与人类环境健康高度相关。

DESCRIPTION (provided by applicant): Heavy metal toxicity is a world-wide health problem. Lead exposure, especially, is of concern due to the adverse effects of low concentrations on cognitive development in children. Whereas neurotoxic mechanisms of lead have been well studied, information regarding genetic susceptibility to the effects of lead exposure in human populations and studies aimed at identifying alleles that may exacerbate or ameliorate exposure risk are lacking. Such information is difficult to obtain, especially in children, because it is dificult to quantify the onset, duration and extent of exposure, measure adverse effects of lead exposure that become manifest at a later stage of development, assess the effects of simultaneous exposure to multiple, often unknown, environmental toxins, and obtain adequate population sample sizes while accounting for population structure. These problems can be circumvented by identifying candidate risk alleles with human orthologues in model systems, which can subsequently be applied in translational studies to human populations. Drosophila melanogaster presents an advantageous model, since both the genetic background and environment, including exposure to lead, can be controlled precisely. This R21 proposal is an exploratory feasibility study to lay the foundation for a subsequent R01 application to exploit the full power of Drosophila genetics to gain insights in the genetic underpinnings of susceptibility t lead exposure. To identify alleles associated with sensitivity to lead exposure, we will take advantage of a population of wild-derived inbred lines from a Raleigh population with fully sequenced genomes (the Drosophila melanogaster Genetic Reference Panel, DGRP) and capitalize on extensive natural variation within the DGRP panel to conduct a genome-wide association study (GWAS). The Specific Aims of this application are: (1) To identify common DNA sequence variants associated with the effects of lead exposure on development time, viability and locomotor activity in 205 inbred wild- derived lines with fully sequenced genomes; and (2) To use massively parallel bulk DNA sequencing as a complementary approach to identify both common and rare alleles associated with effects of lead exposure that segregate in an advanced intercross population derived from extreme sensitive and resistant lines. We will measure development time, viability and locomotor activity in the DGRP lines reared with and without exposure to lead acetate, and identify single nucleotide polymorphisms (SNPs) associated with variation in sensitivity to lead. A subsequent R01 award will focus on a more detailed validation and characterization of candidate alleles, epistatic interactions among them, and the link between genetic networks and neural circuitry that determine sensitivity to lead neurotoxicity. Results from these experiments will be highly relevant to human environmental health.