Chemistry of Selenium in Life and Interplay with Toxic Elements

背景：硒是一种神秘的元素。硒是来自所有王国和三个生命领域的生物体所必需的，是地壳中最稀有的必需元素。在世界范围内，可获得性参差不齐；虽然加拿大大草原等一些地区拥有富含硒的土壤，但在全球范围内，缺硒往往是一个挑战。事实上，在任何必需元素的不足和毒性之间，硒可能是最微妙的平衡。由于食物链中的生物放大作用，即使人类活动导致的环境硒略有升高，也令人担忧。长期以来，人们一直知道硒与某些有毒元素之间存在复杂的相互关系，特别是与汞，这是一种全球关注的元素，由于人类活动，其水平正在上升。虽然硒通常被认为可以降低汞的毒性，但根据汞的化学形式和暴露顺序，硒也可以极大地放大汞的毒性。工作性质这个项目寻求对硒的分子水平功能以及与从环境到人类健康的有毒元素相互作用的整体看法，建立在对硒和同步加速器技术的职业生涯兴趣的基础上。短期目标从新获得的含硒酶及其与汞的相互作用的结构研究开始，探索汞中毒的潜在机制的各个方面。这些链接到生物水平的成像斑马鱼作为模式脊椎动物和组织从高环境暴露，以探索汞中毒的分子影响，特别是汞-硒纳米颗粒的作用。同步加速器X射线方法是该计划的基础。高能量分辨率方法提供下一级物种形成细节以及改进的痕量限制的潜力才刚刚实现；这种方法与显微测绘相结合目前正在同步加速器设施中调试。该计划将帮助确定复杂系统中痕量元素在这些新方向上的最佳实践。新颖性和重要性作为一种微量元素，硒对加拿大既是负担，也是好处。人类活动导致的轻微硒升高可能会通过生态系统生物放大造成问题。相反，加拿大大草原上的富硒土壤可以生产强化的农产品，具有潜在的健康和经济效益。对硒酶的基础研究与我们这个时代突出的健康问题有关，如癌症和糖尿病。硒与汞的复杂关系是一个令人担忧的元素，特别是在加拿大的北极地区，这导致了鱼类等食物以及传统饮食中与汞有关的风险问题。同步加速器的发展将广泛惠及其他从事微量元素生命周期的研究人员，从地球化学和微生物学，到土壤和植物科学，再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.