MUTAGENICITY AND FITNESS IMPACTS OF ENVIRONMENTAL TOXINS

该项目的长期目标是评估暴露在复杂环境毒素混合物中的哺乳动物自然种群的生殖系和体细胞突变率以及个体适应性。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识别诱变性是绝对必要的，并最终增加快速积累的环境化学物质的癌症风险。具体地说，将通过确定鹿鼠后代中新的小卫星片段来估计生殖系突变率，这些片段来自一个受污染的和一个未受污染的地点的小鼠群体。DNA将从父母和后代的外周血白细胞中提取，几个多位点小卫星探针(即Jeffreys的33.6和33.15，合成的M-探针)将被用于产生独立的、高度可变的RFLP图谱(目标A)。接触重金属的水平将通过从受污染地点和未受污染的对照地点提取的土壤和组织样本来估计。多位点DNA指纹图谱将被用来评估在成年鹿小鼠中检测到的任何肿瘤的高变量小卫星座位的体细胞突变率(目标B)。将根据形态特征和生殖性能的不对称性来评估暴露在污染物中的健康后果。为了估计形态不对称性，将对所有个体进行双侧形态测量。所有繁育对的繁殖性能将通过记录每对繁育对的幼崽数量(窝仔数量)、幼崽到断奶的存活率(生存能力)以及出生和断奶时的幼崽质量来监测。(Lacy和Ballou，1998年)(目标C)。为了区分急性毒性和生殖系突变导致的潜在适合度降低，将建立来自实验室饲养的F1代的繁育群体，并监测它们的繁殖成功和后代存活(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)