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

在工业化地区，越来越多具有潜在环境问题的新的有机污染物不断被排放到陆地和水生生态系统中，并有可能发生生物累积，对鸟类等最易受影响的野生物种有毒。这可能是许多新兴的卤化阻燃剂（HFR）的情况，尽管它们在广泛的消费品和工业产品（例如，汽车、电子电路、软垫家具、建筑材料等）达到消防安全标准，即减缓火势蔓延。我的研究小组最近进行的一项研究报告了HFR类多溴联苯醚（PBDEs）的浓度出乎意料的高，以及一些尚未发现的新出现的HFR在城市适应鸟类物种的组织中，环嘴鸥（Larus delawarensis），在蒙特利尔地区繁殖。我的实验室的证据表明，内分泌系统（例如，甲状腺激素水平）和某些相关终点（例如，骨代谢）可能会受到不利影响，在大多数HFR暴露的环嘴鸥。 使用环嘴鸥作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，拟议的研究计划旨在调查环嘴鸥：1）对野生动物物种具有疑似健康问题的新型和新出现的HFRs的生物蓄积动态和母体转移，2）通过分析肝酶的表达、底物特异性和催化活性，确定对选定的高优先级多溴二苯醚和新出现的HFRs的生物转化能力，3）通过分析甲状腺和糖皮质激素水平，研究多溴联苯醚和新出现的HFRs对下丘脑-垂体-甲状腺（HPT）和-肾上腺（HPA）轴的影响，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。 这项工作的新奇和预期意义在于，生物累积、生物转化和与健康有关的影响（例如，内分泌、酶和代谢）对暴露于当前使用的污染物（包括HFRs）的动物的影响是研究不足的领域。这项工作的另一个重要方面是比较方法，即检查自然接触的鸟类种群（野鸥）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提供新的知识，在加拿大环境中的新的化学应激源的动态和生物活性。此外，它代表了动物生物能量学，生态毒理学，毒理学，分析化学和内分泌学新方面的独特HQP培训机会。

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.