A6: DNA PHOTOCLEAVAGE & PHOTOINDUCED TOXICITY OF POLYCYCLIC AROMATIC HYDROCARBON

在这个项目中，光诱导的DNA裂解通过 环境重要致癌物质多环芳烃 (PAH)，并测试其对细菌细胞的遗传毒性 用可见光和UVA光照射不同种类的 将对具有生物重要性的化学物质进行调查。这个 致癌代谢产物7，8-二羟基-9，1-O-环氧基-7，8，9，1 0-四氢苯并[a]芘被发现在辐照时能裂解DNA 355 nm激光。我们的假设是，其他多环芳烃也可以裂解 光化学激发时的DNA和DNA的裂解可能是一个来源 有光毒性。DNA光切割的研究将集中在不同的 多环芳烃，特别是硝基、羟基、甲基和氮杂衍生物以及 他们的代谢物，如二醇环氧化物和二酮。 多环芳烃衍生物对DNA切割的光反应性将是 用质粒DNA进行检测。50%的浓度(C50) 将确定每个多环芳烃的DNA裂解。对经济的影响 具有生物重要性的化学物质、金属离子和 辅酶(NADH、黄素)也将被检测。遗传毒性和 具有明确切割DNA能力的化合物的生态毒性 光化学将与各种微生物进行评估 紫外线照射或室外阳光照射下的生物测定。这个 生物测定包括细菌总数、三磷酸腺苷和 腺苷总浓度、DNA浓度、异养 活性、叶绿素a浓度、微毒素。和Mutatox测试。 将光毒性和DNA光裂解联系起来的图谱将是 已经成立了。最后，考察了不同增敏剂对细胞生长的影响。 将研究多环芳烃的光化学和微生物降解率。 将制定一项议定书，以加强清除和 多环芳烃的脱毒率。DNA最强的化合物 光解裂器将被用于进一步研究光解理。 产品。切割的DNA和多环芳烃的光产物将是 使用一种分析技术的组合进行鉴定：高效液相色谱法。 LC-MS和核磁共振。光诱导DNA裂解的机制将是 从感光产品的结构推断出来的。参与其中的 此外，还将研究活性氧物种和自由基。 结构活性-关系(SAR)将使用50 对于光解和LC*/LOEC，对于光毒-V。

In this project the light-induced DNA cleavage by the environmentally important carcinogen polycyclic aromatic hydrocarbons (PAH) and test their genotoxicity toward bacteria cell upon irradiation with visible and UVA light in the presence of various biologically important chemicals will be investigated. The carcinogenic metabolite 7,8dihydroxy.9,1 O-epoxy-7,8,9,1 0-tetrahydrobenzo[a]pyrene is found to cleave DNA when irradiated with 355 nm laser light. Our hypothesis is that other PAHs can also cleave DNA when photoichemically excited and the DNA cleavage may be a source of phototoxicity. Studies of DNA photocleavage will focus on various PAHs, especially the nitro, hydroxy, methyl, and aza derivatives and their metabolites such as the diol epoxides and diones. Photoreactivity of PAH derivatives toward DNA cleavage will be examined using plasmid DNA. The concentration (C50) at which 50% of DNA cleavage for each PAH will be determined. The effect on the photocleavage by biologically important chemicals, metal ions and coenzymes (NADH, Flavin), will also be examined. Genotoxicity and ecotoxicity of compounds exhibiting clear ability, to cleave DNA photochermically will be evaluated with a variety of microbial bioassays upon UV-Iight or outdoor sun-light irradiation. The bioassays include measurements of total bacterial numbers, ATP and total adenylate concentrations, DNA concentration, heterotrophic activity, chlorophyll a concentration, Microtox. and Mutatox Tests. A profile that relates the photoxicity and DNA photocleavage will be established. Finally, the effect of a variety of sensitizers on the photochemical and microbial degradation rates of PAHs will be studied. A protocol will be established to enhance the removal and detoxification rates of PAHs. Compounds that are strongest DNA photocleavers will be used further for studying the photocleavage products. Photoproducts of both cleaved DNA and PAHs will be identified using a combination of analytical techniques: HPLC. LC-MS, and NMR. Mechanisms for the photoinduced DNA cleavage will be deduced from the structure Of the photoproducts. The involvement of active oxygen species and free radicals will also be studied. Structure Activity- Relationship (SAR) will be studied using the 50 for the photocleavage and LC*/LOEC for the phototoxicit-v.