Pathways of copper acquisition in phytoplankton

浮游植物获取铜的途径

• 批准号: RGPIN-2020-04487
• 负责人: Price, Neil
• 金额: $ 2.04万
• 依托单位: McGill University
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2021
• 资助国家: 加拿大
• 起止时间: 2021-01-01 至 2022-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=739986
• 关键词: Pathways; copper; acquisition; phytoplankton

Metal uptake by phytoplankton is fundamentally important because it links the reactivity of metals in the environment to their physiological and ecological effects in the organisms. Understanding how metals are taken up enables us to predict which chemical forms of metals are bioavailable and which types of phytoplankton will respond to changes in their concentrations. Diatoms and cyanobacteria are two groups of phytoplankton of great significance to aquatic ecosystems. They grow in the open sea in surface waters containing some of lowest levels of metals on Earth although they are exposed to high concentrations transiently because of inputs from dust and upwelling from deep waters. Copper (Cu) is of interest because it is an essential metal for phytoplankton growth and one of the most toxic. Phytoplankton adjust their uptake systems to buffer changes in metal concentrations in the environment to maintain optimal cellular levels, but the details of the uptake pathways are only now being revealed. Copper is utilized by oceanic diatoms by an uptake pathway that uses a chemically reduced form of Cu, Cu(I). The Cu(I) is produced by cellular reduction, but little is known about how cellular reduction is regulated or whether other phytoplankton acquire Cu in the same way. Other groups, like cyanobacteria, may use different pathways for Cu uptake and hence react to different chemical forms of Cu than diatoms. Cyanobacteria, for example, produce compounds that bind Cu to detoxify it, changing the chemistry of Cu in the water and thereby altering its availability to other species. The aims of this research proposal are: 1) to measure the bioavailability of Cu chemical species as a function of Cu nutritional state of diatoms and cyanobacteria, 2) to assess the prevalence of the Cu(II) reduction uptake pathway among different taxonomic groups of phytoplankton and its activation by light, and 3) to describe the Cu-regulated transcriptome of two cyanobacteria and identify differentially expressed genes including putative Cu transport genes induced by Cu deficiency. The proposed research is part of a continuing effort to elucidate the factors regulating phytoplankton growth in the sea. It will provide a mechanistic understanding of Cu uptake by representatives of two ecologically important groups of phytoplankton and identify the potential ecological and biogeochemical consequences of variations in Cu availability. The work is timely given that ocean acidification is predicted to greatly increase the concentration of some inorganic species of Cu and affect Cu complexation by dissolved organic matter. How phytoplankton will be affected by these changes is uncertain as we have a rudimentary understanding of their mechanisms of Cu uptake and know little about the types of Cu species that are available for cellular transport. The research outlined here will begin to fill these gaps in knowledge.

浮游植物对金属的吸收是至关重要的，因为它将环境中金属的活性与它们在生物体中的生理和生态效应联系在一起。了解金属是如何被吸收的，使我们能够预测哪些金属的化学形态是可生物利用的，哪些类型的浮游植物将对其浓度的变化做出反应。硅藻和蓝藻是两类对水生态系统具有重要意义的浮游植物。它们生长在公海的表层水域，含有地球上一些最低水平的金属，但由于灰尘的输入和深水的上涌，它们短暂地暴露在高浓度的环境中。人们对铜很感兴趣，因为它是浮游植物生长所必需的金属，也是毒性最大的金属之一。浮游植物调整它们的吸收系统，以缓冲环境中金属浓度的变化，以维持最佳的细胞水平，但吸收途径的细节直到现在才被揭示。海洋硅藻通过一种利用化学还原形式的铜的吸收途径来利用铜，铜(I)。铜(I)是由细胞还原产生的，但关于细胞还原是如何调节的，或者其他浮游植物是否以同样的方式获得铜，人们知之甚少。其他类群，如蓝藻，可能使用不同的途径吸收铜，因此与硅藻相比，对不同化学形态的铜发生反应。例如，蓝藻会产生与铜结合的化合物来解毒，从而改变水中铜的化学组成，从而改变其对其他物种的有效性。本研究的目的是：1)测量铜化学物种的生物有效性与硅藻和蓝藻的铜营养状态的关系；2)评估不同分类类群浮游植物中铜(II)还原吸收途径的普遍性及其光激活；3)描述两种蓝藻对铜的调控转录组，并寻找差异表达的基因，包括铜缺乏诱导的铜运输基因。这项拟议的研究是阐明控制海洋浮游植物生长的因素的持续努力的一部分。它将提供两个生态上重要的浮游植物群体的代表对铜吸收的机械理解，并确定铜有效性变化的潜在生态和生物地球化学后果。这项工作是及时的，因为据预测，海洋酸化将极大地增加某些无机铜物种的浓度，并影响溶解有机物对铜的络合作用。浮游植物将如何受到这些变化的影响尚不确定，因为我们对它们吸收铜的机制有一个初步的了解，而对可用于细胞运输的铜物种类型知之甚少。这里概述的研究将开始填补这些知识空白。