MUTAGENICITY AND FITNESS IMPACTS OF ENVIRONMENTAL TOXINS

该项目的长期目标是评估生殖细胞和体细胞突变率，以及暴露于复杂环境毒素混合物的哺乳动物自然种群的个体适应性。该项目是一系列评估使用DNA指纹作为诊断分子工具来检测野生哺乳动物对环境诱变剂的显著暴露的第一个项目。这种诊断工具的可用性对于鉴定致突变性以及快速积累的环境化学物质最终增加的癌症风险是绝对必要的。具体而言，生殖系突变率将通过确定来自一个污染和一个未污染地点的小鼠菌落的鹿小鼠后代中的新小卫星片段来估计。从父母和后代的外周血白细胞中提取DNA，并使用几种多位点小卫星探针（即，Jeffreys的33.6和33.15，合成M探针）将用于产生独立的、高度可变的RFLP模式（目标A）。将通过污染场地和未污染对照场地的土壤和组织样本估计重金属暴露水平。多位点DNA指纹分析将用于评估成年鹿小鼠中任何检出肿瘤的高变小卫星位点的体细胞突变率（目标B）。将根据形态特征和生殖性能的不对称性评估暴露于污染物的健身后果。为了估计形态不对称性，将对所有个体进行双侧形态测量。将通过记录每对繁殖对的幼仔数量（窝仔数）、幼仔至断奶的存活率（活力）以及出生和断奶时幼仔的质量来监测所有繁殖对的生殖性能。(Lacy和Jiangsu 1998）（目标C）。为了区分急性毒性与种系突变导致的潜在适应性降低，将建立来自实验室饲养的F1代的繁殖菌落，并监测其繁殖成功率和后代存活率（目标D）

The long-term objectives of this project are to assess germline and somatic mutation rates, and individual fitness in a natural population of mammals exposed to complex mixtures of environmental toxins. This project is the first in a series to evaluate the use of DNA fingerprinting as a diagnostic molecular tool to detect significant exposure of wild mammals to environmental mutagens. Availability of such a diagnostic tool is absolutely essential to identify mutagenicity, and ultimately increased risk of cancer for rapidly accumulating environmental chemicals. Specifically, germ line mutation rates will be estimated by determining novel minisatellite fragments in deer mouse progeny for mouse colonies derived from one contaminated and one uncontaminated site. DNA will be extracted from peripheral blood leukocytes obtained from parents and offspring, and several multilocus, minisatellite probes (i.e., Jeffreys' 33.6, and 33.15, synthetic M-probe) will be used to generate independent, highly variable RFLP patterns (Objective A). Levels of exposure to heavy metals will be estimated through soil and tissue samples derived from the contaminated site, and the uncontaminated control site. Multilocus DNA fingerprinting will be used to assess somatic mutation rates at hypervariable minisatellite loci for any detected tumors among adult deer mice (Objective B). Fitness consequences of exposure to pollutants will be assessed based on asymmetry of morphological traits and reproductive performance. In order to estimate morphological asymmetry, bilateral morphological measurements will be taken for all individuals. Reproductive performance of all breeding pairs will be monitored by recording number of pups per breeding pair (litter size), survival of pups to weaning (viability), and mass of pups at birth and weaning. (Lacy and Ballou 1998) (Objective C). To distinguish potential fitness reduction due to acute toxicity versus germline mutations, breeding colonies derived from the laboratory-raised F1 generation will be established, and their reproductive success and offspring survival will be monitored (Objective D)