Understanding the Factors Driving Intra-Specific Tissue Variations, and the Endocrine and Metabolic Impacts of Flame Retardant Exposure in Birds

越来越多的可能引起环境关注的新的有机污染物不断排放到工业化地区的陆地和水生生态系统中，这些污染物有可能产生生物积累，并对鸟类等最易受影响的野生物种产生毒性。这可能是许多新兴卤化阻燃剂（HFRs）的情况，尽管它们在广泛的消费和工业产品（例如，汽车，电子电路，软垫家具，建筑材料等）中大量使用，以达到消防安全标准，即减缓火灾的蔓延，但没有国家或国际法规。我的研究小组最近进行的一项研究报告，在蒙特利尔地区繁殖的一种适应城市的鸟类——环嘴鸥（Larus delawarensis）的组织中，意外地发现了高浓度的HFR类多溴联苯醚（PBDEs），以及几种尚未发现的新出现的HFRs。我的实验室证据表明，内分泌系统（如甲状腺激素水平）和某些相关终点（如骨代谢）可能会对大多数暴露于hfr的环嘴鸥产生不利影响。***本研究以环嘴鸥为大蒙特利尔地区和圣劳伦斯河环境HFR暴露和生态系统健康的生物指示物种，对环嘴鸥进行研究：1)新型和新兴的疑似健康问题的HFRs对野生物种的生物积累动力学和母体转移；2)通过分析肝脏酶的表达、底物特异性和催化活性，对选定的高优先级多溴二苯醚和新兴HFRs的生物转化能力；3)通过分析甲状腺和糖皮质激素水平、参与调节这些内分泌轴以及能量消耗（代谢率）的选定基因的转录，多溴二苯醚和新出现的HFRs对下丘脑-垂体-甲状腺（HPT）和肾上腺（HPA）轴的暴露相关影响。***这项工作的新颖性和预期意义在于，暴露于包括HFRs在内的当前使用的污染物的动物的生物积累，生物转化和暴露相关的健康影响（例如，内分泌，酶和代谢）是尚未充分研究的研究领域。这项工作的另一个重要方面是比较方法，即检查自然暴露的鸟类种群（野生海鸥）和圈养鸟类模型（鸡）之间化学诱导效应的差异。因此，这项拟议的研究计划将为加拿大环境中新型化学应激源的动力学和生物活性提供新的知识。此外，它代表了一个独特的HQP培训机会，在动物生物能量学，生态毒理学，毒物动力学，分析化学和内分泌学的新方面

A growing number of new organic contaminants of potential environmental concern are constantly discharged into terrestrial and aquatic ecosystems in industrialized regions, and have the potential to bioaccumulate and be toxic to the most susceptible wildlife species such as birds. This may be the case for the numerous emerging halogenated flame retardants (HFRs) for which no national or international regulations exist despite their massive usage in a wide range of consumer and industrial products (e.g., cars, electronic circuitry, upholstered furniture, construction materials, etc.) to achieve fire safety standards, that is, to slow down the spread of fire. A recent study conducted by my research group reported unexpectedly high concentrations of the HFR class polybrominated diphenyl ethers (PBDEs) as well as several as yet undetected emerging HFRs in tissues of a urban-adapted avian species, the ring-billed gull (Larus delawarensis), breeding in the Montreal area. Evidence from my laboratory suggests that the endocrine system (e.g., thyroid hormone levels) and certain related endpoints (e.g., bone metabolism) may be adversely affected in the most HFR-exposed ring-billed gulls. ***Using the ring-billed gull as bioindicator species of environmental HFR exposure and ecosystem health in the greater Montreal area and St. Lawrence River, the proposed research program aims to investigate in ring-billed gulls: 1) the bioaccumulation dynamics and maternal transfer of novel and emerging HFRs of suspected health concern to wildlife species, 2) the biotransformation capacity towards selected high-priority PBDEs and emerging HFRs via analysis of the expression, substrate specificity, and catalytic activity of hepatic enzymes, and 3) the exposure-related effects of PBDEs and emerging HFRs on hypothalamic-pituitary-thyroid (HPT) and -adrenal (HPA) axes via analysis of thyroid and glucocorticoid hormone levels, transcription of selected genes involved in the regulation of these endocrine axes as well as energy expenditure (metabolic rates).***The novelty and expected significance of this work is that the bioaccumulation, biotransformation, and exposure-related health impacts (e.g., endocrine, enzymatic, and metabolic) on animals exposed to currently-used contaminants including HFRs are understudied fields of research. One other significant aspect of this work is the comparative approach, that is, the examination of differences in chemically-induced effects among naturally-exposed bird populations (wild gull) and a captive avian model (chicken). This proposed research program will thus provide new knowledge on the dynamics and bioactivity of novel chemical stressors in the Canadian environment. Furthermore, it represents a unique HQP training opportunity in novel aspects of animal bioenergetics, ecotoxicology, toxicokinetics, analytical chemistry, and endocrinology.**