Understanding the Factors Driving Intra-Specific Variations of Contaminants in Urban-Adapted Birds and their Endocrine and Metabolic Impacts

在高度城市化的环境中，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陆地和水生生态系统中，并有可能产生生物积累，对鸟类等最易受影响的野生物种具有毒性。这可能是许多新兴的卤化阻燃剂（HFRs）的情况，尽管它们在世界范围内广泛的消费和工业产品中大量（并且不断增长）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存在。我的实验室最近进行的一项研究报告称，在蒙特利尔地区繁殖的大量适应城市的鸟类——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。我实验室的证据表明，内分泌系统（如甲状腺轴）和某些相关终点（如能量代谢）可能会对大多数暴露于hfr的环嘴鸥产生不利影响。NSERC DG研究计划的短期目标是：1)研究影响野生动物健康的新型和新兴HFRs在环嘴鸥中的生物积累和母体转移的生物学因素；2)环嘴鸥对新发HFRs的体外生物转化能力；3)通过分析甲状腺激素和皮质酮水平、参与其调控的基因mRNA转录、脂质组成（脂质组学）和野外代谢率（FMR；测量动物的总能量消耗），研究选定的新发HFRs对环嘴鸥和鸡两个内分泌轴的暴露相关效应和潜在毒性机制。拟议研究的新颖性和预期意义在于，暴露于当前使用的污染物（包括HFRs）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、代谢率、脂质代谢）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（海鸥）和鸟类模型（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，它将为动物生物能量学，生态毒理学，生物能量学，内分泌学，分析化学和脂质组学的新方面的一名博士和三名硕士学生以及五名学士荣誉学生提供独特的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 highly urbanized environments, 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 (and growing) usage worldwide in a wide range of consumer and industrial products to achieve fire safety standards, that is, to slow down the spread of fire. A recent study conducted by my lab reported unexpectedly high concentrations of the HFR class polybrominated diphenyl ethers (PBDEs) as well as several as yet undetected emerging HFRs in tissues of an abundant urban-adapted avian species, the ring-billed gull (Larus delawarensis), breeding in the Montreal area. Evidence from my lab suggests that the endocrine system (e.g., thyroid axis) and certain related endpoints (e.g., energetic metabolism) may be adversely affected in the most HFR-exposed ring-billed gulls. The short-term objectives of the proposed NSERC DG research program will be to investigate: 1) the biological factors governing the bioaccumulation and maternal transfer in ring-billed gulls of novel and emerging HFRs of greatest health concern for wildlife; 2) the in vitro biotransformation capacity in ring-billed gulls towards selected emerging HFRs; and 3) the exposure-related effects and underlying mechanisms of toxicity of selected emerging HFRs on two endocrine axes in ring-billed gulls and chicken via analysis of thyroid hormone and corticosterone levels, mRNA transcription of genes involved in their regulation as well as lipid composition (lipidomics) and field metabolic rate (FMR; measures an animal's total energy expenditure). The novelty and expected significance of the proposed research is that the bioaccumulation, biotransformation, and exposure-related health impacts (e.g., endocrine, metabolic rate, lipid metabolism) 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 (gull) and an 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 will represent a unique HQP training opportunity for one Ph.D. and three M.Sc. students as well as five B.Sc. honour students in novel aspects of animal bioenergetics, ecotoxicology, bioenergetics, endocrinology, analytical chemistry, and lipidomics.