Chemistry of Selenium in Life and Interplay with Toxic Elements

硒是一种神秘的元素。硒是所有生物界和三个生命领域中必不可少的元素，是地壳中最稀有的必需元素。在世界范围内，硒的供应是不平衡的;虽然加拿大大草原等一些地区的土壤富含硒，但全球硒缺乏往往是一个挑战。事实上，硒可能是任何必需元素中营养不足和毒性之间最微妙的平衡。由于食物网中的生物放大作用，人类活动导致的环境硒即使略微升高也令人担忧。硒长期以来与某些有毒元素，特别是与汞的复杂相互关系而闻名，汞是一种全球关注的元素，其水平由于人类活动而不断上升。虽然硒通常被认为可以降低汞的毒性，但硒也可以极大地放大汞的毒性，这取决于它们的化学形式和暴露顺序。工作性质该计划寻求硒的分子水平功能和通过人类健康与环境中的有毒元素相互作用的整体观点，建立在硒和同步加速器技术的职业生涯的兴趣基础上。短期目标从新的含硒酶的结构研究及其与汞的相互作用开始，探索汞中毒的潜在机制。这些链接到生物体水平的成像斑马鱼作为一种模型脊椎动物和组织从高环境暴露，探测汞中毒的分子影响，特别是汞硒纳米粒子的作用。同步加速器X射线方法是该计划的基础。高能量分辨率的方法，以提供下一个级别的形态细节沿着与改进的痕量限制的潜力只是刚刚实现，这种方法结合显微镜映射目前正在调试中的同步加速器设施。该计划将有助于在这些新的方向为复杂系统中的微量元素定义最佳实践。硒作为一种微量元素，对加拿大来说既是一种负担，也是一种利益。人类活动造成的硒轻微升高会通过生态系统的生物放大作用造成问题。相反，加拿大大草原的富硒土壤导致强化农产品，具有潜在的健康和经济效益。硒酶的基础研究与我们这个时代的主要健康问题，如癌症和糖尿病有关。硒与汞之间的复杂关系是一个令人关注的因素，尤其是在加拿大的北极地区，这有助于解决与鱼类等食物以及传统饮食中的汞有关的风险问题。同步加速器的发展将使其他研究人员广泛受益于微量元素的整个生命周期，从地球化学和微生物学，通过土壤和植物科学，到生态系统和人类健康。

BACKGROUND Selenium is an enigmatic element. Essential in organisms from all kingdoms and three domains of life, selenium is the rarest required element in the Earth's crust. Worldwide, availability is uneven; while some areas such as the Canadian prairies have soils rich in selenium, globally selenium deficiency is often a challenge. Indeed, selenium has perhaps the most delicate balance between insufficiency and toxicity of any essential element. Even slightly elevated environmental selenium from human activities is of concern due to biomagnification in the food web. Selenium is long known for complex interrelationship with certain toxic elements, especially with mercury, an element of global concern whose levels are rising due to human activities. While selenium is often thought to decrease mercury's toxicity, selenium can also greatly amplify mercury's toxicity, depending on their chemical forms and order of exposure. NATURE OF THE WORK This program seeks a holistic view of selenium's molecular level function and interaction with toxic elements from environment through human health, building on a career-long interest in selenium and synchrotron technologies. Short term objectives start from structural studies of newly available selenium-containing enzymes and their interactions with mercury, probing facets of potential mechanisms of mercury poisoning. These link to organism-level imaging of zebrafish as a model vertebrate and tissues from high environmental exposure, to probe molecular impacts of mercury poisoning, especially the role of mercury-selenium nanoparticles. Synchrotron X-ray methods underpin the program. The potential of high energy resolution methods to provide next-level speciation detail along with improved trace limits is only just being realized; such methods combined with microscopic mapping currently are in commissioning at synchrotron facilities. This program will help define best practices in these new directions for trace elements in complex systems. NOVELTY AND SIGNIFICANCE Selenium as a trace element is both a burden and a benefit to Canada. Slightly elevated selenium from anthropogenic activity can cause problems through ecosystem biomagnification. Conversely, selenium-rich soils across Canada's prairies lead to fortified agricultural products, with potential health and economic benefit. Fundamental studies on selenoenzymes connect to preeminent health concerns of our time such as cancer and diabetes. Selenium's complex relationship with mercury, an element of concern especially in Canada's Arctic, contributes to the question of risk associated with mercury in food such as fish as well as in traditional diets. Synchrotron developments will broadly benefit other researchers engaged across the lifecycle of trace elements, from geochemistry and microbiology, through soil and plant sciences, to ecosystem and human health.